The use of soil pollen to determine the sex of overhead individuals of a temperate dioecious shrub.

PubMed

Sugiyama, Anna; Shichi, Koji; Masaki, Takashi; Hubbell, Stephen P

2017-04-01

In dioecious species, determining the sex of individual plants from one-time phenological observations is rarely feasible when some individuals capable of reproducing are not flowering or fruiting at the time of observation. Currently, sexing those individuals requires long-term phenological data on individuals and populations, but such data are rarely available or feasible to collect. We tested the hypothesis that differences in soil pollen concentrations beneath the crowns of female and male plants would exist and be sufficient to reliably determine the sex of the individual plant overhead in a dioecious species. We predicted that soil pollen concentrations beneath male plants would be significantly higher than beneath female plants because only males produce pollen and pollen should accumulate in the soil underneath the male plants over repeated flowering events. We collected samples from surface soil under both sexes of the insect-pollinated dioecious shrub, Aucuba japonica (Garryaceae). Pollen grains were present in surface soil in both Oe and A horizons, and mean pollen concentration under males was significantly higher than under females. Pollen concentrations beneath males were positively correlated with male plant height, potentially reflecting greater pollen production by larger individuals. Considering the small plant size and relatively low pollen production of A. japonica , this method may hold promise for sexing other dioecious species in the absence of direct phenological data. Our phenology-free and relatively low-cost method for sexing dioecious plants may be especially useful in tropical forests where many species are dioecious. © 2017 Botanical Society of America.

New evidence on the hydrothermal system in Long Valley caldera, California, from wells, fluid sampling, electrical geophysics, and age determinations of hot-spring deposits

USGS Publications Warehouse

Sorey, M.L.; Suemnicht, G.A.; Sturchio, N.C.; Nordquist, G.A.

1991-01-01

Data collected since 1985 from test drilling, fluid sampling, and geologic and geophysical investigations provide a clearer definition of the hydrothermal system in Long Valley caldera than was previously available. This information confirms the existence of high-temperature (> 200??C) reservoirs within the volcanic fill in parts of the west moat. These reservoirs contain fluids which are chemically similar to thermal fluids encountered in the central and eastern parts of the caldera. The roots of the present-day hydrothermal system (the source reservoir, principal zones of upflow, and the magmatic heat source) most likely occur within metamorphic basement rocks beneath the western part of the caldera. Geothermometer-temperature estimates for the source reservoir range from 214 to 248??C. Zones of upflow of hot water could exist beneath the plateau of moat rhyolite located west of the resurgent dome or beneath Mammoth Mountain. Lateral flow of thermal water away from such upflow zones through reservoirs in the Bishop Tuff and early rhyolite accounts for temperature reversals encountered in most existing wells. Dating of hot-spring deposits from active and inactive thermal areas confirms previous interpretations of the evolution of hydrothermal activity that suggest two periods of extensive hot-spring discharge, one peaking about 300 ka and another extending from about 40 ka to the present. The onset of hydrothermal activity around 40 ka coincides with the initiation of rhyolitic volcanism along the Mono-Inyo Craters volcanic chain that extends beneath the caldera's west moat. ?? 1991.

Long-term fate of depleted uranium at Aberdeen and Yuma Proving Grounds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ebinger, M.H.; Essington, E.H.; Gladney, E.S.

1990-06-01

The environmental fate of fragments of depleted uranium (DU) penetrators in soils and waters at Aberdeen Proving Ground (APG) and Yuma Proving Ground (YPG) is a concern to the Testing and Evaluation Command (TECOM) of the US Army. This report presents the information from preliminary soil and water samples that were collected from the humid woodlands of APG and the arid Sonoran Desert of YPG. Soil samples collected beneath a penetrator fragment of the firing range at APG showed approximately 12% DU by weight in the surface horizon and DU significantly above background to a depth of about 20 cm.more » Samples of surface water at APG showed U only at background levels, and bottom sediments showed background U levels but with isotopic ratios of DU instead of natural U. Soil samples beneath a penetrator fragment at YPG showed about 0.5% by weight U in the surface horizon, but only background concentrations and isotopic ratios of U between 8 and 20 cm depth. Results from this preliminary study indicate that DU at APG was redistributed primarily be dissolution and transport with water and possibly by migration of DU colloids or DU attached to small particles. Redistribution at YPG, however, was mainly due to erosion of DU fragments from the impact area and redeposition in washes that drain the area. Proposed work for FY90-FY92 includes additional field sampling, laboratory column studies, and the development of a computer model of DU redistribution at both sites. 39 refs., 11 figs., 5 tabs.« less

Mixing of Magmatic Volatiles With Meteoric Groundwater in the Summit of Kilauea Volcano, Hawaii

NASA Astrophysics Data System (ADS)

Hurwitz, S.; Goff, F.; Janik, C. J.; Evans, W. C.; Counce, D. A.; Sorey, M. L.; Ingebritsen, S. E.

2001-12-01

Water samples were collected from the only deep well (Keller Well-NSF Well) on the summit of Kilauea volcano, Hawaii. The well was drilled in 1973 to a depth of 1262 m, but sat idle until 1998 when a drilling rig was used to remove mud and renew access to the hydrothermal system at a location very close to summit fumarolic activity. The chemistry and isotopic composition of fluid samples collected in 1998-2001 differ significantly from those of samples collected before 1998 and reported in previous studies. The water from the well is rich in sulfate and has a near-neutral pH. The major element chemistry differs significantly from seawater composition and from that of hydrothermal fluids from Kilauea's east rift zone. The well water has a low chloride concentration relative to typical magmatic-hydrothermal fluids and a high sulfate to bicarbonate ratio (approximately 4:1). Based on the S/Cl mass ratio and on carbon and helium isotopes in the well fluids, summit fumaroles and the parental Kilauea magma, we conclude that the hydrothermal fluids sampled from the well formed by condensation of magmatic volatiles into shallow, mainly meteoric groundwater. The oxygen and deuterium isotopic composition indicate that the meteoric component was recharged on the eastern margin of the caldera. Steam condensation and gas dissolution beneath the crater formed an acidic fluid that dissolved the host basalt at high temperatures. The hydrothermal fluid was then modified by cooling and precipitation of secondary minerals along a flow path away from the crater towards the well. Geochemical modeling based on fluid chemistry and geothermometry suggests that the well fluids equilibrated with an assemblage of secondary minerals at temperatures between 90 and 140oC. The C/S ratios in the well water, the parental magma, and the gas plume emanating from the caldera indicate that most of the sulfur degassed from the magma is scrubbed by groundwaters beneath the summit. However, based on the mean sulfate concentration in the well water and on the estimated mean annual water recharge in the caldera region, we conclude that the sulfate concentration in groundwater beneath Kilauea's summit must be an order of magnitude higher than that found in the well water.

3D soil structure characterization of Biological Soil Crusts from Alpine Tarfala Valley

NASA Astrophysics Data System (ADS)

Mele, Giacomo; Gargiulo, Laura; Zucconi, Laura; D'Acqui, Luigi; Ventura, Stefano

2017-04-01

Cyanobacteria filaments, microfungal hyphae, lichen rhizinae and anchoring rhizoids of bryophytes all together contribute to induce formation of structure in the thin soil layer beneath the Biological Soil Crusts (BSCs). Quantitative assessment of the soil structure beneath the BSCs is primarily hindered by the fragile nature of the crusts. Therefore, the role of BSCs in affecting such soil physical property has been rarely addressed using direct measurements. In this work we applied non-destructive X-ray microtomography imaging on five different samples of BSCs collected in the Alpine Tarfala Valley (northern Sweden), which have already been characterized in terms of fungal biodiversity in a previous work. We obtained images of the 3D spatial organization of the soil underneath the BSCs and characterized its structure by applying procedures of image analysis allowing to determine pore size distribution, pore connectivity and aggregate size distribution. Results has then been correlated with the different fungal assemblages of the samples.

Radiocarbon dates for lava flows and pyroclastic deposits on Sao Miguel, Azores

USGS Publications Warehouse

Moore, R.B.; Rubin, M.

1991-01-01

We report 63 new radiocarbon analyses of samples from Sao Miguel, the largest island in the Azores archipelago. The samples are mainly carbonized tree roots and other plant material collected from beneath 20 mafic lava flows and spatter deposits and from within and beneath 42 trachytic pyroclastic flow, pyroclastic surge, mudflow, pumice-fall and lacustrine deposits and lava flows. One calcite date is reported. These dates establish ages for 48 previously undated lava flows and pyroclastic deposits, and revise three ages previously reported. These data are critical to deciphering the Holocene and late Pleistocene eruptive history of Sao Miguel and evaluating its potential volcanic hazards. Average dormant intervals during the past 3000 years are about 400 years for Sete Cidades volcano, 145 years for volcanic Zone 2, 1150 years for Agua de Pau volcano and 320 years for Furnas volcano. No known eruptions have occurred in volcanic Zone 4 during the past 3000 years. -from Authors

Airborne measurements of tropospheric ozone destruction and particulate bromide formation in the Arctic

NASA Technical Reports Server (NTRS)

Schnell, Russell C.; Sheridan, Patrick J.; Peterson, Richard E.; Oltmans, S. J.

1988-01-01

Aircraft profiles of O3 concentrations over the Arctic ice pack in spring exhibit a depletion of O3 beneath the surface temperature inversion. One such profile from the NOAA WP-3D Arctic Gas and Aerosol Sampling Program (AGASP) flights in April, 1986 north of Alert, NWT (YLT, 82.5 N) is shown. The gradient of O3 across the temperature inversion, which is essentially a step function from tropospheric values (35 to 40 ppbv) to 0, is somewhat masked by a 1-min running mean applied to the data. Evidence is presented that O3 destruction beneath the Arctic temperature inversion is the result of a photochemical reaction between gaseous Br compounds and O3 to produce particulate Br aerosol. It is noted that in springtime, O3 at the Alert Baseline Station regularly decreases from 30 to 40 ppbv to near 0 over the period of a few hours to a day. At the same time, there is a production of particulate Br with a near 1.0 anti-correlation to O3 concentration. Surface concentrations of bromoform in the Arctic exhibit a rapid decrease following polar sunrise. AGASP aircraft measurements of filterable bromine particulates in the Arctic (March-April, 1983 and 1986) are shown. The greatest concentrations of Br aerosol (shown as enrichment factors relative to to Na in seawater, EFBR (Na)) were observed in samples collected beneath the surface temperature inversion over ice. Samples collected at the same altitude over open ocean (off Spitzbergen) labeled Marine did not exhibit similar Br enrichments. A second region of particulate Br enrichment was observed in the lower stratosphere, which regularly descends to below 500 mb (5.5 km) in the high Arctic. The NOAA WP-3D flew in the stratosphere on all AGASP flights and occasionally measured O3 concentrations in excess of 300 ppbv.

Reconnaissance of water quality in the High Plains Aquifer beneath agricultural lands, south-central Kansas

USGS Publications Warehouse

Stullken, L.E.; Stamer, J.K.; Carr, J.E.

1987-01-01

The High Plains of western Kansas was one of 14 areas selected for preliminary groundwater quality reconnaissance by the U.S. Geological Survey 's Toxic Waste--Groundwater Contamination Program. The specific objective was to evaluate the effects of land used for agriculture (irrigated cropland and non-irrigated rangeland) on the water in the High Plains aquifer. Conceptual inferences, based on the information available, would lead one to expect groundwater beneath irrigated cropland to contain larger concentrations of sodium, sulfate, chloride, nitrite plus nitrate, and some water soluble pesticides than water beneath non-irrigated land (range-land) The central part of the Great Bend Prairie, an area of about 1,800 sq mi overlying the High Plains aquifer in south-central Kansas, was selected for the study of agricultural land use because it has sand soils, a shallow water table, relatively large annual precipitation, and includes large areas that are exclusively irrigated cropland or non-irrigated rangeland. As determined by a two-tailed Wilcoxon rank-sum test, concentrations of sodium and alkalinity were significantly larger at the 95% confidence level for water samples from beneath irrigated cropland than from beneath rangeland. No statistically significant difference in concentrations of sulfate, chloride, nitrite plus nitrate, and ammonia, was detected. Concentrations of 2,4-D found in water samples from beneath the rangeland were larger at the 99% confidence level as compared to concentrations of 2,4-D in samples from beneath irrigated cropland. Larger concentrations of sodium and alkalinity were found in water beneath irrigated cropland, and the largest concentration of the pesticide atrazine (triazines were found in three samples) was found in water from the only irrigation well sampled. The sodium and atrazine concentrations found in water from the irrigation well support the premise that water-level drawdown develops under irrigated fields. This diverts the natural groundwater flow patterns, so that pumpage may cause recycling and subsequent concentration of leachates from the land surface. (Author 's abstract)

Imaging the Lowermost Mantle (D'') Beneath the Pacific Ocean with SKKS coda waves

NASA Astrophysics Data System (ADS)

Yu, Z.; Shang, X.; van der Hilst, R. D.

2013-12-01

Previous studies indicate considerable complexity in the lowermost mantle beneath the Pacific Ocean on a variety of spatial scales, such as large low-shear-velocity province (LLSVP), intermittent D'' discontinuities and isolated ultra-low-velocity zones (ULVZs). However, the resolution of travel time tomography is typically greater than 1000 km in deep mantle, and only a few regions can satisfy contingent sampling requirement for waveform modeling. On the other hand, generalized Radon transform (GRT) has a higher resolution (~400 km horizontally and ~30 km vertically) and can relax the restriction of source-receiver configuration. It has been successfully applied to central America and east Asia, which are speculated as the graveyard of subducted slabs. In this study we apply GRT to obtain a large-scale high-resolution image beneath (almost the whole) Pacific Ocean near the core-mantle boundary (CMB). More than 400,000 traces from ~8,000 events (5.8

Underwater microscope for measuring spatial and temporal changes in bed-sediment grain size

USGS Publications Warehouse

Rubin, David M.; Chezar, Henry; Harney, Jodi N.; Topping, David J.; Melis, Theodore S.; Sherwood, Christopher R.

2007-01-01

For more than a century, studies of sedimentology and sediment transport have measured bed-sediment grain size by collecting samples and transporting them back to the laboratory for grain-size analysis. This process is slow and expensive. Moreover, most sampling systems are not selective enough to sample only the surficial grains that interact with the flow; samples typically include sediment from at least a few centimeters beneath the bed surface. New hardware and software are available for in situ measurement of grain size. The new technology permits rapid measurement of surficial bed sediment. Here we describe several systems we have deployed by boat, by hand, and by tripod in rivers, oceans, and on beaches.

Underwater Microscope for Measuring Spatial and Temporal Changes in Bed-Sediment Grain Size

USGS Publications Warehouse

Rubin, David M.; Chezar, Henry; Harney, Jodi N.; Topping, David J.; Melis, Theodore S.; Sherwood, Christopher R.

2006-01-01

For more than a century, studies of sedimentology and sediment transport have measured bed-sediment grain size by collecting samples and transporting them back to the lab for grain-size analysis. This process is slow and expensive. Moreover, most sampling systems are not selective enough to sample only the surficial grains that interact with the flow; samples typically include sediment from at least a few centimeters beneath the bed surface. New hardware and software are available for in-situ measurement of grain size. The new technology permits rapid measurement of surficial bed sediment. Here we describe several systems we have deployed by boat, by hand, and by tripod in rivers, oceans, and on beaches.

Remote Oil Spill Detection and Monitoring Beneath Sea Ice

NASA Astrophysics Data System (ADS)

Polak, Adam; Marshall, Stephen; Ren, Jinchang; Hwang, Byongjun (Phil); Hagan, Bernard; Stothard, David J. M.

2016-08-01

The spillage of oil in Polar Regions is particularly serious due to the threat to the environment and the difficulties in detecting and tracking the full extent of the oil seepage beneath the sea ice. Development of fast and reliable sensing techniques is highly desirable. In this paper hyperspectral imaging combined with signal processing and classification techniques are proposed as a potential tool to detect the presence of oil beneath the sea ice. A small sample, lab based experiment, serving as a proof of concept, resulted in the successful identification of oil presence beneath the thin ice layer as opposed to the other sample with ice only. The paper demonstrates the results of this experiment that granted a financial support to execute full feasibility study of this technology for oil spill detection beneath the sea ice.

Biting rates and developmental substrates for biting midges (Diptera: Ceratopogonidae) in Iquitos, Peru.

PubMed

Mercer, David R; Spinelli, Gustavo R; Watts, Douglas M; Tesh, Robert B

2003-11-01

Biting midges (Diptera: Ceratopogonidae) were collected at 16 periurban and rural sites around Iquitos, Peru, between 17 October 1996 and 26 May 1997. Culicoides paraensis (Goeldi), the principal vector of Oropouche virus, was the most commonly collected species (9,086 flies) with Culicoides insinuatus Wirth & Blanton second (7,229 flies). Although both species were collected at all sampling sites (linear (distance surveyed approximately 25 km), C. paraensis dominated at northern collection sites (> 90%), whereas C. insinuatus prevailed at southern collection sites (> 60%). C. paraensis were collected from human sentinels at a constant rate throughout daylight hours, at similar rates during wet and dry months, and regardless of rainfall. Larval developmental substrates for C. paraensis included decaying platano (Musa x paradisiaca L. [Musaceae]) stems, stumps, flowers, fruits, and debris beneath platano trees as well as from soil beneath a fruiting mamay (Syzygium malaccense Merr. & Perry [Myrtaceae] ) tree and organic-rich mud along a lake shoreline. C. insinuatus adults likewise emerged from decaying platano and organic-rich mud along a lake shoreline, but also from debris accumulated in the axils of aguaje (Mauritia flexuosa L. [Palmae]) fronds and decaying citrus fruit. Despite high numbers of biting adults near putative substrates, adults of neither species emerged from other decomposing plant material, soil, phytotelmata, or artificial containers. Because both species of biting midges emerged in high numbers from all parts of platano (ubiquitous in Iquitos), it will be challenging to control them through sanitation.

Insights in groundwater organic matter from Liquid Chromatography-Organic Carbon Detection

NASA Astrophysics Data System (ADS)

Rutlidge, H.; Oudone, P.; McDonough, L.; Andersen, M. S.; Baker, A.; Meredith, K.; O'Carroll, D. M.

2017-12-01

Understanding the processes that control the concentration and characteristics of organic matter in groundwater has important implications for the terrestrial global carbon budget. Liquid Chromatography - Organic Carbon Detection (LC-OCD) is a size-exclusion based chromatography technique that separates the organic carbon into molecular weight size fractions of biopolymers, humic substances, building blocks (degradation products of humic substances), low molecular weight acids and low molecular weight neutrals. Groundwater and surface water samples were collected from a range of locations in Australia representing different surface soil, land cover, recharge type and hydrological properties. At one site hyporheic zone samples were also collected from beneath a stream. The results showed a general decrease in the aromaticity and molecular weight indices going from surface water, hyporheic downwelling and groundwater samples. The aquifer substrate also affected the organic composition. For example, groundwater samples collected from a zone of fractured rock showed a relative decrease in the proportion of humic substances, suggestive of sorption or degradation of humic substances. This work demonstrates the potential for using LC-OCD in elucidating the processes that control the concentration and characteristics of organic matter in groundwater.

Metagenomic Assessment of a Dynamic Microbial Population from Subseafloor Aquifer Fluids in the Cold, Oxygenated Crust

NASA Astrophysics Data System (ADS)

Tully, B. J.; Heidelberg, J. F.; Kraft, B.; Girguis, P. R.; Huber, J. A.

2016-12-01

The oceanic crust contains the largest aquifer on Earth with a volume approximately 2% of the global ocean. Ongoing research at the North Pond (NP) site, west of the Mid-Atlantic Ridge, provides an environment representative of oxygenated crustal aquifers beneath oligotrophic surface waters. Using subseafloor CORK observatories for multiple sampling depths beneath the seafloor, crustal fluids were sampled along the predicted aquifer fluid flow path over a two-year period. DNA was extracted and sequenced for metagenomic analysis from 22 crustal fluid samples, along with the overlying bottom. At broad taxonomic groupings, the aquifer system is highly dynamic over time and space, with shifts in dominant taxa and "blooms" of transient groups that appear at discreet time points and sample depths. We were able to reconstruct 194 high-quality, low-contamination bacterial and archaeal metagenomic-assembled genomes (MAGs) with estimated completeness >50% (429 MAGs >20% complete). Environmental genomes were assigned to phylogenies from the major bacterial phyla, putative novel groups, and poorly sampled phylogenetic groups, including the Marinimicrobia, Candidate Phyla Radiation, and Planctomycetes. Biogeochemically relevant processes were assigned to MAGs, including denitrification, dissimilatory sulfur and hydrogen cycling, and carbon fixation. Collectively, the oxic NP aquifer system represents a diverse, dynamic microbial habitat with the metabolic potential to impact multiple globally relevant biogeochemical cycles, including nitrogen, sulfur, and carbon.

Use of environmental tracers to study the chemical evolution of shallow ground water in a karst area of northern Florida

DOE Office of Scientific and Technical Information (OSTI.GOV)

Katz, B.G.; Plummer, L.N.; Busenberg, E.

1993-03-01

The pathways of shallow ground-water flow in poorly confined aquifer systems of northern FL are influenced by inflow to and outflow from numerous sinkhole lakes that are characteristic of the Sand Hills karst region. Ground-water samples were collected immediately upgradient and downgradient from Lake Barco at depths of 1.6--29 m below the water table from observation wells completed in the surficial aquifer system, the intermediate confining unit (icu), and the Upper Floridan aquifer. Samples were also collected of rainfall, lake water, and ground water at a depth of 4.1 m beneath the lake bottom. The environmental tracers tritium and chlorofluorocarbonsmore » were used to estimate mean residence times of water and rates of chemical mass transfer along flow paths. Water samples collected from wells upgradient of the lake were oxic and had CFC-model recharge dates between 1971 and 1986. The content of delta H-2 and delta O-18 of water from the two aquifer systems and the icu was nearly identical to the isotopic composition of rainfall. Changes in the chemical composition of the ground water with depth were simulated by reacting rainfall with minerals and dissolved gases that exist in the hydrogeologic units. Ground-water samples collected from sites beneath and downgradient of the lake were anoxic, with measured concentrations of hydrogen sulfide and methane ranging from 0.02--0.58 mg/l and 0.30--6.1 mg/l, respectively. CFC-model recharge dates ranged from 1956 to 1983. The data indicated that ground water downgradient of the lake is being recharged by leakage of lake water. The chemical composition of ground water is influenced by the movement of lake water through reducing, organic-rich sediments accumulated at the bottom. Along the downgradient flow paths, the water chemistry evolves from the composition of lake water and is modified by subsequent reactions including reduction of sulfate and ferric iron, methanogenesis, and dissolution and precipitation of minerals.« less

Geochemical and isotopic study of impact melts and spherules from the Lonar impact crater, India, indicate melting of the Precambrian basement beneath the 'target' Deccan basalts

NASA Astrophysics Data System (ADS)

Chakrabarti, R.; Goderis, S.; Banerjee, A.; Gupta, R. D.; Claeys, P.; Vanhaecke, F. F.

2016-12-01

The 1.88 km diameter Lonar impact Crater, with age estimates ranging from 52 -570 ka, is located in the Buldana district of Maharashtra, India. It is an almost circular depression hosted entirely in the 65Ma old basalt flows of the Deccan Traps and is the best-known terrestrial analogue for impact craters in the Inner Solar System. Isotopic studies indicate that the basalts around Lonar correlate with the Poladpur suite, one of the mid-section volcano-stratigraphic units of the Deccan traps. Recently collected samples of the host basalt and impact melts, were analyzed for major and trace element concentrations using ICPMS, as well as for Nd and Sr isotope ratios using TIMS. Relatively more radiogenic Sr and less radiogenic Nd isotopic composition of the melt rocks compared to earlier measurements of similar rocks from Lonar are consistent with melting of the Precambrian basement beneath the Deccan basalt. Spherules ranging in size from 100 mm to 1 mm, were hand-picked under a binocular microscope from unconsolidated soil samples, collected from the south-eastern rim of the crater. Thirty-five spherule samples, screened for surface alteration using SEM were analyzed for major and trace element concentrations including PGEs using LA-ICPMS. The spherules were further classified into two groups using the Chemical Index of Alteration(CIA). Iridium and Cr concentrations of the spherules are consistent with mixing of a chondritic impactor (with 2-8% contribution) with the target rock(s). On a Nb (fluid immobile) -normalized binary plot of Th versus Cr, the composition of the spherules can be explained by mixing between the host basalt and a chondritic impactor with a definite, but minor contribution of the basement beneath Lonar, the composition of which is approximated using the average composition of the upper continental crust (UCC). Variability in the light-REE fractionation of the spherules (La/Sm(N)) can also be explained by a similar three component mixing. Overall, our geochemical data for both the melt rocks and spherules suggest mixing between the chondritic impactor, the Deccan host basalt and the basement rocks at Lonar.

Noble gas isotopes in mineral springs and wells within the Cascadia forearc, Washington, Oregon, and California

USGS Publications Warehouse

McCrory, Patricia A.; Constantz, James E.; Hunt, Andrew G.

2017-01-31

IntroductionThis U.S. Geological Survey report presents laboratory analyses along with field notes for an exploratory study to document the relative abundance of noble gases in mineral springs and water wells within the Cascadia forearc of Washington, Oregon, and California (fig. 1). This report describes 14 samples collected in 2014 and 2015 and complements a previous report that describes 9 samples collected in 2012 and 2013 (McCrory and others, 2014b). Estimates of the depth to the underlying Juan de Fuca oceanic plate beneath sample sites are derived from the McCrory and others (2012) slab model. Some of the springs have been previously sampled for chemical analyses (Mariner and others, 2006), but none of the springs or wells currently has publicly available noble gas data. The helium and neon isotope values and ratios presented below are used to determine the sources and mixing history of these mineral and well waters (for example, McCrory and others, 2016).

The Bossons glacier protects Europe's summit from erosion

NASA Astrophysics Data System (ADS)

Godon, C.; Mugnier, J. L.; Fallourd, R.; Paquette, J. L.; Pohl, A.; Buoncristiani, J. F.

2013-08-01

The contrasting efficiency of erosion beneath cold glacier ice, beneath temperate glacier ice, and on ice-free mountain slopes is one of the key parameters in the development of relief during glacial periods. Detrital geochronology has been applied to the subglacial streams of the north face of the Mont-Blanc massif in order to estimate the efficiency of erosional processes there. Lithologically this area is composed of granite intruded at ~303 Ma within an older polymetamorphic complex. We use macroscopic features (on ~10,000 clasts) and U-Pb dating of zircon (~500 grains) to establish the provenance of the sediment transported by the glacier and its subglacial streams. The lithology of sediment collected from the surface and the base of the glacier is compared with the distribution of bedrock sources. The analysis of this distribution takes into account the glacier's surface flow lines, the surface areas beneath temperate and cold ice above and below the Equilibrium Line Altitude (ELA), and the extent of the watersheds of the three subglacial meltwater stream outlets located at altitudes of 2300 m, 1760 m and 1450 m. Comparison of the proportions of granite and metamorphics in these samples indicates that (1) glacial transport does not mix the clasts derived from subglacial erosion with the clasts derived from supraglacial deposition, except in the lower part of the ice tongue where supraglacial streams and moulins transfer the supraglacial load to the base of the glacier; (2) the glacial erosion rate beneath the tongue is lower than the erosion rate in adjacent non-glaciated areas; and (3) glacial erosion beneath cold ice is at least 16 times less efficient than erosion beneath temperate ice. The low rates of subglacial erosion on the north face of the Mont-Blanc massif mean that its glaciers are protecting "the roof of Europe" from erosion. A long-term effect of this might be a rise in the maximum altitude of the Alps.

Groundwater geochemical and selected volatile organic compound data, Operable Unit 1, Naval Undersea Warfare Center, Division Keyport, Washington, June and October 2012

USGS Publications Warehouse

Huffman, R.L.

2013-01-01

Previous investigations indicate that concentrations of chlorinated volatile organic compounds are substantial in groundwater beneath the 9-acre former landfill at Operable Unit 1, Naval Undersea Warfare Center, Division Keyport, Washington. The U.S. Geological Survey has continued to monitor groundwater geochemistry to ensure that conditions remain favorable for contaminant biodegradation as specified in the Record of Decision for the site. This report presents groundwater geochemical and selected chlorinated volatile organic compound data collected at Operable Unit 1 by the U.S. Geological Survey during June and October 2012, in support of long-term monitoring for natural attenuation. Groundwater samples were collected from 13 wells and 9 piezometers, as well as from 10 shallow groundwater passive-diffusion sampling sites in the nearby marsh. Samples from all wells and piezometers were analyzed for oxidation-reduction (redox) sensitive constituents and dissolved gases. Samples from all piezometers also were analyzed for chlorinated volatile organic compounds, as were all samples from the passive-diffusion sampling sites. In 2012, concentrations of redox-sensitive constituents measured at all wells and piezometers were consistent with those measured in previous years, with dissolved oxygen concentrations all at 0.4 milligram per liter or less; little to no detectable nitrate; abundant dissolved manganese, iron, and methane; and commonly detected sulfide. In the upper aquifer of the northern plantation in 2012, chlorinated volatile organic compound (CVOC) concentrations at all piezometers were similar to those measured in previous years, and concentrations of the reductive dechlorination byproducts ethane and ethene were slightly higher or the same as concentrations measured in 2011. In the upper aquifer of the southern plantation, CVOC concentrations measured in piezometers during 2012 continued to be extremely variable as in previous years, and often very high, and reductive dechlorination byproducts were detected in two of the four wells and in all piezometers. Beneath the marsh adjacent to the southern plantation, chloroethene concentrations measured in 2012 continued to vary spatially and temporarily, and also were very high. Additionally, CVOC concentrations measured in samplers deployed in access tubes were about two to four times less than those measured in the two samplers buried nearby, beneath the marsh stream. Total CVOC concentration, at what has been historically the most contaminated passive-diffusion sampler site (S-4), continued an increasing trend. For the intermediate aquifer in 2012, concentrations of reductive dechlorination byproducts ethane and ethene were consistent with those measured in previous years.

Blue Oak Canopy Effect on Seasonal Forage Production and Quality

Treesearch

William E. Frost; Neil K. McDougald; Montague W. Demment

1991-01-01

Forage production and forage quality were measured seasonally beneath the canopy of blue oak (Quercus douglasii) and in open grassland at the San Joaquin Experimental Range. At the March and peak standing crop sampling dates forage production was significantly greater (p=.05) beneath blue oak compared to open grassland. At most sampling dates, the...

The Internet of Samples in the Earth Sciences (iSamples)

NASA Astrophysics Data System (ADS)

Carter, M. R.; Lehnert, K. A.

2015-12-01

Across most Earth Science disciplines, research depends on the availability of samples collected above, at, and beneath Earth's surface, on the moon and in space, or generated in experiments. Many domains in the Earth Sciences have recently expressed the need for better discovery, access, and sharing of scientific samples and collections (EarthCube End-User Domain workshops, 2012 and 2013, http://earthcube.org/info/about/end-user-workshops), as has the US government (OSTP Memo, March 2014). The Internet of Samples in the Earth Sciences (iSamples) is an initiative funded as a Research Coordination Network (RCN) within the EarthCube program to address this need. iSamples aims to advance the use of innovative cyberinfrastructure to connect physical samples and sample collections across the Earth Sciences with digital data infrastructures to revolutionize their utility for science. iSamples strives to build, grow, and foster a new community of practice, in which domain scientists, curators of sample repositories and collections, computer and information scientists, software developers and technology innovators engage in and collaborate on defining, articulating, and addressing the needs and challenges of physical samples as a critical component of digital data infrastructure. A primary goal of iSamples is to deliver a community-endorsed set of best practices and standards for the registration, description, identification, and citation of physical specimens and define an actionable plan for implementation. iSamples conducted a broad community survey about sample sharing and has created 5 different working groups to address the different challenges of developing the internet of samples - from metadata schemas and unique identifiers to an architecture of a shared cyberinfrastructure for collections, to digitization of existing collections, to education, and ultimately to establishing the physical infrastructure that will ensure preservation and access of the physical samples. Creating awareness of the need to include physical samples in discussions of reproducible science is another priority of the iSamples RCN.

Yucca Mountain Area Saturated Zone Dissolved Organic Carbon Isotopic Data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thomas, James; Decker, David; Patterson, Gary

2007-06-25

Groundwater samples in the Yucca Mountain area were collected for chemical and isotopic analyses and measurements of water temperature, pH, specific conductivity, and alkalinity were obtained at the well or spring at the time of sampling. For this project, groundwater samples were analyzed for major-ion chemistry, deuterium, oxygen-18, and carbon isotopes of dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC). The U.S. Geological Survey (USGS) performed all the fieldwork on this project including measurement of water chemistry field parameters and sample collection. The major ions dissolved in the groundwater, deuterium, oxygen-18, and carbon isotopes of dissolved inorganic carbon (DIC)more » were analyzed by the USGS. All preparation and processing of samples for DOC carbon isotopic analyses and geochemical modeling were performed by the Desert Research Institute (DRI). Analysis of the DOC carbon dioxide gas produced at DRI to obtain carbon-13 and carbon-14 values was conducted at the University of Arizona Accelerator Facility (a NSHE Yucca Mountain project QA qualified contract facility). The major-ion chemistry, deuterium, oxygen-18, and carbon isotopes of DIC were used in geochemical modeling (NETPATH) to determine groundwater sources, flow paths, mixing, and ages. The carbon isotopes of DOC were used to calculate groundwater ages that are independent of DIC model corrected carbon-14 ages. The DIC model corrected carbon-14 calculated ages were used to evaluate groundwater travel times for mixtures of water including water beneath Yucca Mountain. When possible, groundwater travel times were calculated for groundwater flow from beneath Yucca Mountain to down gradient sample sites. DOC carbon-14 groundwater ages were also calculated for groundwaters in the Yucca Mountain area. When possible, groundwater travel times were estimated for groundwater flow from beneath Yucca Mountain to down gradient groundwater sample sites using the DOC calculated groundwater ages. The DIC calculated groundwater ages were compared with DOC calculated groundwater ages and both of these ages were compared to travel times developed in ground-water flow and transport models. If nuclear waste is stored in Yucca Mountain, the saturated zone is the final barrier against the release of radionuclides to the environment. The most recent rendition of the TSPA takes little credit for the presence of the saturated zone and is a testament to the inadequate understanding of this important barrier. If radionuclides reach the saturated zone beneath Yucca Mountain, then there is a travel time before they would leave the Yucca Mountain area and flow down gradient to the Amargosa Valley area. Knowing how long it takes groundwater in the saturated zone to flow from beneath Yucca Mountain to down gradient areas is critical information for potential radionuclide transport. Radionuclide transport in groundwater may be the quickest pathway for radionuclides in the proposed Yucca Mountain repository to reach land surface by way of groundwater pumped in Amargosa Valley. An alternative approach to ground-water flow and transport models to determine the travel time of radionuclides from beneath Yucca Mountain to down gradient areas in the saturated zone is by carbon-14 dating of both inorganic and organic carbon dissolved in the groundwater. A standard method of determining ground-water ages is to measure the carbon-13 and carbon-14 of DIC in the groundwater and then correct the measured carbon-14 along a flow path for geochemical reactions that involve carbon containing phases. These geochemical reactions are constrained by carbon-13 and isotopic fractionations. Without correcting for geochemical reactions, the ground-water ages calculated from only the differences in carbon-14 measured along a flow path (assuming the decrease in carbon-14 is due strictly to radioactive decay) could be tens of thousands of years too old. The computer program NETPATH, developed by the USGS, is the best geochemical program for correcting carbon-14 activities for geochemical reactions. The DIC carbon-14 corrected ages can be further constrained by measuring the carbon isotopes of DOC. Because the only source of organic carbon in aquifers is almost always greater than 40,000 years old, any organic carbon that may be added to the groundwater would contain no carbon-14. Thus, ground-water ages determined by carbon isotopes of DOC should be maximum ages that can be used to constrain DIC corrected ages.« less

Throughfall chemistry beneath Quercus rubra: atmospheric, foliar, and soil chemistry considerations

Treesearch

Theodor D. Leininger; W.E. Winner

1988-01-01

Concentrations of inorganic ions were measured in bulk rainfall and bulk throughfall collected beneath northern red oak (Quercus rubra L.) trees growing in fertile, limestone-derived soil and less fertile sandstone/shale-derived soil. Rainfall passing through the crowns at both sites was enriched with SO2-4...

Rayleigh-wave dispersion reveals crust-mantle decoupling beneath eastern Tibet.

PubMed

Legendre, Cédric P; Deschamps, Frédéric; Zhao, Li; Chen, Qi-Fu

2015-11-09

The Tibetan Plateau results from the collision of the Indian and Eurasian Plates during the Cenozoic, which produced at least 2,000 km of convergence. Its tectonics is dominated by an eastward extrusion of crustal material that has been explained by models implying either a mechanical decoupling between the crust and the lithosphere, or lithospheric deformation. Discriminating between these end-member models requires constraints on crustal and lithospheric mantle deformations. Distribution of seismic anisotropy may be inferred from the mapping of azimuthal anisotropy of surface waves. Here, we use data from the CNSN to map Rayleigh-wave azimuthal anisotropy in the crust and lithospheric mantle beneath eastern Tibet. Beneath Tibet, the anisotropic patterns at periods sampling the crust support an eastward flow up to 100°E in longitude, and a southward bend between 100°E and 104°E. At longer periods, sampling the lithospheric mantle, the anisotropic structures are consistent with the absolute plate motion. By contrast, in the Sino-Korean and Yangtze cratons, the direction of fast propagation remains unchanged throughout the period range sampling the crust and lithospheric mantle. These observations suggest that the crust and lithospheric mantle are mechanically decoupled beneath eastern Tibet, and coupled beneath the Sino-Korean and Yangtze cratons.

Radioactivity in the environment; a case study of the Puerco and Little Colorado River basins, Arizona and New Mexico

USGS Publications Warehouse

Wirt, Laurie

1994-01-01

This report, written for the nontechnical reader, summarizes the results of a study from 1988-91 of the occurrence and transport of selected radionuclides and other chemical constituents in the Puerco and Little Colorado River basins, Arizona and New Mexico. More than two decades of uranium mining and the 1979 failure of an earthen dam containing mine tailings released high levels of radionuclides and other chemical constituents to the Puerco River, a tributary of the Little Colorado River. Releases caused public concern that ground water and streamflow downstream from mining were contaminated. Study findings show which radioactive elements are present, how these elements are distributed between water and sediment in the environment, how concentrations of radioactive elements vary naturally within basins, and how levels of radioactivity have changed since the end of mining. Although levels of radioactive elements and other trace elements measured in streamflow commonly exceed drinking-water standards, no evidence was found to indicate that the high concentrations were still related to uraniurn mining. Sediment radioactivity was higher at sample sites on streams that drain the eastern part of the Little Colorado River basin than that of samples from the western part. Radioactivity of suspended sediment measured in this study, therefore, represents natural conditions for the streams sampled rather than an effect of mining. Because ground water beneath the Puerco River channel is shallow, the aquifer is vulnerable to contamination. A narrow zone of ground water beneath the Puerco River containing elevated uranium concentrations was identified during the study. The highest concentrations were nearest the mines and in samples collected in the first few feet beneath the streambed. Natuxal radiation levels in a few areas of the underlying sedimentary aquifer not connected to the Puerco River also exceeded water quality standards. Water testing would enable those residents not using public water supplies to determine if their water is safe to use.

The diatom record from beneath the West Antarctic Ice Sheet and the global proxy perspective

NASA Technical Reports Server (NTRS)

Scherer, Reed P.

1993-01-01

Recent glaciological evaluation and modeling of the marine-based West Antarctic Ice Sheet (WAIS) support the possibility that the WAIS disintegrated during one or more Pleistocene interglacial period(s). The magnitude of sea level and oxygen isotope variation during certain late-Pleistocene interglacial periods is also consistent with the possibility of major retreat of the WAIS. Although oxygen isotopes from deep-sea sediments provide the best available proxy record for global ice volume (despite the ambiguities in the record), the source of ice volume changes must be hypothesized. Based on the intensity of interglacial isotopic shifts recorded in Southern Ocean marine sedimentary records, stage 11 (400,000 years ago) is the strongest candidate for WAIS collapse, but the records for stages 9, 7, and 5.5 are all consistent with the possibility of multiple late-Pleistocene collapses. Seismic reflection studies through the WAIS have revealed thick successions of strata with seismic characteristics comparable to upper Tertiary marine sediments. Small samples of glacial diamictons from beneath the ice sheet have been collected via hot-water drilled access holes. These sediments include mixed diatom assemblages of varying ages. Late-Miocene diatoms dominate many samples, probably reflecting marine deposition in West Antarctic basins prior to development of a dominantly glacial phase in West Antarctica. In addition to late-Miocene diatoms, samples from Upstream B (1988/89) contain rare post-Miocene diatoms, many of which imply deposition in the West Antarctic interior during one or more Pleistocene deglaciation periods. Age-diagnostic fossils in glacial sediments beneath ice sheets provide relatively coarse chronostratigraphic control, but they do contain direct evidence of regional deglaciation. Thus, sub-glacial till samples provide the evidence regarding the source of ice sheet variability seen in well-dated proxy records. Combined, these independent data sets can provide a more comprehensive and less speculative interpretation of the history of past glacial minima in currently glaciated polar regions.

Reconnaissance of Organic Wastewater Compounds at a Concentrated Swine Feeding Operation in the North Carolina Coastal Plain, 2008

USGS Publications Warehouse

Harden, Stephen L.

2009-01-01

Water-quality and hydrologic data were collected during 2008 to examine the occurrence of organic wastewater compounds at a concentrated swine feeding operation located in the North Carolina Coastal Plain. Continuous groundwater level and stream-stage data were collected at one monitoring well and one stream site, respectively, throughout 2008. One round of environmental and quality-control samples was collected in September 2008 following a period of below-normal precipitation and when swine waste was not being applied to the spray fields. Samples were collected at one lagoon site, seven shallow groundwater sites, and one surface-water site for analysis of 111 organic wastewater compounds, including household, industrial, and agricultural-use compounds, sterols, pharmaceutical compounds, hormones, and antibiotics. Analytical data for environmental samples collected during the study provide preliminary information on the occurrence of organic wastewater compounds in the lagoon-waste source material, groundwater beneath fields that receive spray applications of the lagoon wastes, and surface water in the tributary adjacent to the site. Overall, 28 organic wastewater compounds were detected in the collected samples, including 11 household, industrial, and agricultural-use compounds; 3 sterols; 2 pharmaceutical compounds; 5 hormones; and 7 antibiotics. The lagoon sample had the greatest number (20) and highest concentrations of compounds compared to groundwater and surface-water samples. The antibiotic lincomycin had the maximum detected concentration (393 micrograms per liter) in the lagoon sample. Of the 11 compounds identified in the groundwater and surface-water samples, all with reported concentrations less than 1 microgram per liter, only lincomycin identified in groundwater at 1 well and 3-methyl-1H-indole and indole identified in surface water at 1 site also were identified in the lagoon waste material.

Mineral precipitation and dissolution at two slag-disposal sites in northwestern Indiana, USA

USGS Publications Warehouse

Bayless, E.R.; Schulz, M.S.

2003-01-01

Slag is a ubiquitous byproduct of the iron- and steel-refining industries. In northwestern Indiana and northeastern Illinois, slag has been deposited over more than 52 km2 of land surface. Despite the widespread use of slag for fill and construction purposes, little is known about its chemical effects on the environment. Two slagdisposal sites were examined in northwestern Indiana where slag was deposited over the native glacial deposits. At a third site, where slag was not present, background conditions were defined. Samples were collected from cores and drill cuttings and described with scanning electron microscopy and electron microprobe analysis. Ground-water samples were collected and used to assess thermodynamic equilibria between authigenic minerals and existing conditions. Differences in the mineralogy at background and slag-affected sites were apparent. Calcite, dolomite, gypsum, iron oxides, and clay minerals were abundant in native sediments immediately beneath the slag. Mineral features indicated that these minerals precipitated rapidly from slag drainage and co-precipitated minor amounts of non-calcium metals and trace elements. Quartz fragments immediately beneath the slag showed extensive pitting that was not apparent in sediments from the background site, indicating chemical weathering by the hyperalkaline slag drainage. The environmental impacts of slag-related mineral precipitation include disruption of natural ground-water flow patterns and bed-sediment armoring in adjacent surface-water systems. Dissolution of native quartz by the hyperalkaline drainage may cause instability in structures situated over slag fill or in roadways comprised of slag aggregates.

Hydrologic data from selected wells in the Helena Valley, Lewis and Clark County, Montana

USGS Publications Warehouse

Moreland, Joe A.; Leonard, R.B.; Reed, T.E.; Clausen, R.O.; Wood, W.A.

1979-01-01

Hydrologic data were collected during 1978-79 to aid in evaluating the hydrologic conditions in shallow aquifers beneath the Helena Valley, Montana. The locations of 52 shallow test wells augered during the study are shown on a map at a scale of 1:48,000. Periodic water-level measurements and water-quality analyses for the test holes are listed in tables. Water temperature, specific conductance, and nitrate concentration are given for water samples collected from 98 domestic wells, and chemical analyses are included for 11 domestic and irrigation wells. In addition, water-level drawdown and recovery data are plotted on graphs for five pumped wells and three observation wells. (Kosco-USGS)

Assessment of Soil-Gas, Surface-Water, and Soil Contamination at the Installation Railhead, Fort Gordon, Georgia, 2008-2009

USGS Publications Warehouse

Landmeyer, James E.; Harrelson, Larry G.; Ratliff, W. Hagan; Wellborn, John B.

2010-01-01

The U.S. Geological Survey, in cooperation with the U.S. Department of the Army Environmental and Natural Resources Management Office of the U.S. Army Signal Center and Fort Gordon, assessed soil gas, surface water, and soil for contaminants at the Installation Railhead (IR) at Fort Gordon, Georgia, from October 2008 to September 2009. The assessment included delineation of organic contaminants present in soil-gas samples beneath the IR, and in a surface-water sample collected from an unnamed tributary to Marcum Branch in the western part of the IR. Inorganic contaminants were determined in a surface-water sample and in soil samples. This assessment was conducted to provide environmental contamination data to Fort Gordon personnel pursuant to requirements of the Resource Conservation and Recovery Act Part B Hazardous Waste Permit process. Soil-gas samples collected within a localized area on the western part of the IR contained total petroleum hydrocarbons; benzene, toluene, ethylbenzene, and total xylenes (referred to as BTEX); and naphthalene above the method detection level. These soil-gas samples were collected where buildings had previously stood. Soil-gas samples collected within a localized area contained perchloroethylene (PCE). These samples were collected where buildings 2410 and 2405 had been. Chloroform and toluene were detected in a surface-water sample collected from an unnamed tributary to Marcum Branch but at concentrations below the National Primary Drinking Water Standard maximum contaminant level (MCL) for each compound. Iron was detected in the surface-water sample at 686 micrograms per liter (ug/L) and exceeded the National Secondary Drinking Water Standard MCL for iron. Metal concentrations in composite soil samples collected at three locations from land surface to a depth of 6 inches did not exceed the U.S. Environmental Protection Agency Regional Screening Levels for industrial soil.

Investigation of ground-water contamination at a drainage ditch, Installation Restoration Site 4, Naval Air Station Corpus Christi, Corpus Christi, Texas, 2005–06

USGS Publications Warehouse

Vroblesky, Don A.; Casey, Clifton C.

2007-01-01

The U.S. Geological Survey, in cooperation with the Naval Facilities Engineering Command Southeast, used newly developed sampling methods to investigate ground-water contamination by chlorobenzenes beneath a drainage ditch on the southwestern side of Installation Restoration Site 4, Naval Air Station Corpus Christi, Corpus Christi, Texas, during 2005-06. The drainage ditch, which is a potential receptor for ground-water contaminants from Installation Restoration Site 4, intermittently discharges water to Corpus Christi Bay. This report uses data from a new type of pore-water sampler developed for this investigation and other methods to examine the subsurface contamination beneath the drainage ditch. Analysis of ground water from the samplers indicated that chlorobenzenes (maximum detected concentration of 160 micrograms per liter) are present in the ground water beneath the ditch. The concentrations of dissolved oxygen in the samples (less than 0.05-0.4 milligram per liter) showed that the ground water beneath and near the ditch is anaerobic, indicating that substantial chlorobenzene biodegradation in the aquifer beneath the ditch is unlikely. Probable alternative mechanisms of chlorobenzene removal in the ground water beneath the drainage ditch include sorption onto the organic-rich sediment and contaminant depletion by cattails through uptake, sorption, and localized soil aeration.

Phase I Source Investigation, Heckathorn Superfund Site, Richmond, California

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kohn, Nancy P; Evans, Nathan R

This report represents Phase I of a multi-phase approach to a source investigation of DDT at the Heckathorn Superfund Site, Richmond, California, the former site of a pesticide packaging plant, and the adjacent waterway, the Lauritzen Channel. Potential identified sources of contamination were from sloughed material from undredged areas (such as side banks) and from outfall pipes. Objectives of Phase I included the (1) evaluation of pesticide concentrations associated with discharge from outfalls, (2) identification of additional outfalls in the area, (3) identification of type, quantity, and distribution of sediment under the Levin pier, (4) quantification of pesticide concentrations inmore » sediment under the pier, and (5) evaluation of sediment structure and slope stability under the pier. Field operations included the collection of sediment directly from inside the mouths of outfall pipes, when possible, or the deployment of specially designed particle traps where direct sampling was problematic. Passive water samplers were placed at the end of known outfall pipes and analyzed for DDT and other pesticides of concern. Underwater dive surveys were conducted beneath the Levin pier to document type, slope, and thickness of sediment. Samples were collected at locations of interest and analyzed for contaminants. Also sampled was soil from bank areas, which were suspected of potentially contributing to continued DDT contamination of the Lauritzen Channel through erosion and groundwater leaching. The Phase I Source Investigation was successful in identifying significant sources of DDT contamination to Lauritzen Channel sediment. Undredged sediment beneath the Levin pier that has been redistributed to the channel is a likely source. Two outfalls tested bear further investigation. Not as well-defined are the contributions of bank erosional material and groundwater leaching. Subsequent investigations will be based on the results of this first phase.« less

Carbonate system at Iheya North in Okinawa Trough~IODP drilling and post drilling environment~

NASA Astrophysics Data System (ADS)

Noguchi, T.; Hatta, M.; Sunamura, M.; Fukuba, T.; Suzue, T.; Kimoto, H.; Okamura, K.

2012-12-01

The Iheya North hydrothermal field in middle Okinawa Trough is covered with thick hemipelagic and volcanic sediment. Geochemical characteristics of Okinawa Trough is to provide abundant of CO2, CH4, NH4, H2, and H2S which originated from magmatic gases, sedimentary organic matters. On this hydrothermal field, a scientific drilling by Integrated Ocean Drilling Program (IODP) Expedition 331 was conducted to investigate metabolically diverse subseafloor microbial ecosystem and their physical and chemical settings. To clarify the spatial distribution of physical condition beneath seafloor around the hydrothermal filed, we focus on the carbonate species analysis to reconstruct in-situ pH, which regulate the diversities of microbial community and mineral composition. We developed the small sample volume dissolved total inorganic carbon (DIC) analyzer and conducted the onboard analysis for the interstitial water during IODP Exp.331. Total alkalinity, boron, phosphate, and ammonium also analyzed for thermodynamic calculation. In this presentation, we represent the spatial distribution of pH beneath the Iheya North hydrothermal field. In addition, we developed a 128 bottles multiple water sampler (ANEMONE) for post drilling environmental monitoring. ANEMONE sampler was deployed on the manned submersible Shinkai 6500 with other chemical sensors (CTD, turbidity, pH, ORP, and H2S), and collected the hydrothermal plume samples every 5 minutes during YK12-05 cruise by R/V Yokosuka (Japan Agency for Marine-Earth Science and Technology, JAMSTEC). DIC concentration of plume samples collected by ANEMONE sampler were analyzed just after submersible retrieve, and nutrients, manganese, density, and total cell counts determination were conducted onshore analysis. Based on these results, we describe the spatial distribution of DIC and carbonate system on Iheya North hydrothermal field (interstitial water, hydrothermal fluid, and hydrothermal plume).

Summer cover crops reduce atrazine leaching to shallow groundwater in southern Florida.

PubMed

Potter, Thomas L; Bosch, David D; Joo, Hyun; Schaffer, Bruce; Muñoz-Carpena, Rafael

2007-01-01

At Florida's southeastern tip, sweet corn (Zea Mays) is grown commercially during winter months. Most fields are treated with atrazine (6-chloro-N-ethyl-N'-[1-methylethyl]-1,3,5-triazine-2,4-diamine). Hydrogeologic conditions indicate a potential for shallow groundwater contamination. This was investigated by measuring the parent compound and three degradates--DEA (6-chloro-N-[1-methylethyl]-1,3,5-triazine-2,4-diamine), DIA (6-chloro-N-ethyl)-1,3,5-triazine-2,4-diamine, and HA (6-hydroxy-N-[1-methylethyl]-1,3,5-triazine-2,4-diamine)--in water samples collected beneath sweet corn plots treated annually with the herbicide. During the study, a potential mitigation measure (i.e., the use of a cover crop, Sunn Hemp [Crotalaria juncea L.], during summer fallow periods followed by chopping and turning the crop into soil before planting the next crop) was evaluated. Over 3.5 yr and production of four corn crops, groundwater monitoring indicated leaching of atrazine, DIA, and DEA, with DEA accounting for more than half of all residues in most samples. Predominance of DEA, which increased after the second atrazine application, was interpreted as an indication of rapid and extensive atrazine degradation in soil and indicated that an adapted community of atrazine degrading organisms had developed. A companion laboratory study found a sixfold increase in atrazine degradation rate in soil after three applications. Groundwater data also revealed that atrazine and degradates concentrations were significantly lower in samples collected beneath cover crop plots when compared with concentrations below fallow plots. Together, these findings demonstrated a relatively small although potentially significant risk for leaching of atrazine and its dealkylated degradates to groundwater and that the use of a cover crop like Sunn Hemp during summer months may be an effective mitigation measure.

Environmental occurrence and shallow ground water detection of the antibiotic monensin from dairy farms

USGS Publications Warehouse

Watanabe, N.; Harter, T.H.; Bergamaschi, B.A.

2008-01-01

Pharmaceuticals used in animal feeding operations have been detected in various environmental settings. There is a growing concern about the impact on terrestrial and aquatic organisms and the development of antibiotic-resistant strains of microorganisms. Pharmaceutical use in milking cows is relatively limited compared with other livestock operations, except for the ionophore monensin, which is given to lactating cows as a feed. By weight, monensin can be the most significant antibiotic used in a dairy farm. This study investigates the potential of monensin to move from dairy operations into the surrounding ground water. Using two dairy farms in California as study sites, we twice collected samples along the environmental pathway-from flush lanes, lagoon waters, and shallow ground water beneath the dairies and beneath its associated manured fields. Monensin concentrations were determined using solid-phase extraction and liquid chromatography-tandem mass spectrometry with positive electrospray ionization. Monensin was detected in all of the flush lane and lagoon water samples. Theoretical maximum concentration estimated from the actual dosing rate and the theoretical excretion rate assuming no attenuation was one order of magnitude greater than observed concentrations, suggesting significant attenuation in the manure collection and storage system. Monensin was also detected, at levels ranging from 0.04 to 0.39 microg L(-1), in some of the ground water samples underneath the production area of the dairy but not from the adjacent manured fields. Concentrations in ground water immediately downgradient of the lagoons were one to two orders of magnitude lower than the concentrations detected in lagoons, suggesting attenuation in the subsurface. The data suggest the possibility of monensin transport into shallow (2-5 m) alluvial ground water from dairy management units, including manure storage lagoons and freestalls occupied by heifers, lactating cows, and dry cows.

Male DNA under female fingernails after scratching: transfer and persistence evaluation by RT-PCR analysis and Y-STR typing.

PubMed

Iuvaro, Alessandra; Bini, Carla; Dilloo, Silvia; Sarno, Stefania; Pelotti, Susi

2018-04-17

The collection of biological debris beneath fingernails can be useful in forensic casework when a struggle between the victim and the offender is suspected. In the present study, we set up a controlled scratching experiment in which female volunteers scratched the male volunteers' forearms, simulating a defensive action during an assault. A total of 160 fingernail samples were collected: 80 "control samples" before the scratching, 40 samples immediately after the scratching (t = 0 h), and 40 samples 5 h after the scratching (t = 5 h). The aim was to evaluate, using a real-time PCR approach and Y-STR profiling, the transfer and the persistence of male DNA under female fingernails after scratching. A significant reduction in DNA yield was observed between fingernail samples collected immediately and those collected 5 h after scratching, with a corresponding decrease in Y-STR profile quality. Overall, 38/40 (95%) of the fingernail samples collected immediately (t = 0 h) and 24/40 (60%) of those collected 5 h later (t = 5 h) were suitable for comparison and the scratched male volunteers could not be excluded as donors of the foreign DNA from 37 (92.5%) of the t = 0 h and from 10 (25%) of the t = 5 h profiles. The analysis of male DNA under female fingernails showed that Y-chromosome STR typing may provide extremely valuable genetic information of the male contributor(s), although 5 h after scratching the profile of the scratched male was lost in three-quarters of samples.

Detrital zircon U-Pb Geochronology of the Boleo Formation of Santa RosalÍa Basin, Baja California Sur, México

NASA Astrophysics Data System (ADS)

Henry, M.; Alvarez Ortega, K. G.; Banes, A.; Holm-Denoma, C.; Busby, C.; Niemi, T.

2017-12-01

The Santa Rosalía Basin (SRB) is a rift basin related to the opening of the Gulf of California. The Boleo Formation is the oldest and dominant sedimentary fill of the SRB, with a poorly constrained age. We carried out a U-Pb detrital zircon (DZ) study of the Boleo Formation to constrain its maximum depositional age. The Boleo Formation has a basal limestone-gypsum section, overlain by an up to 250 m thick clastic sequence, with coarsening upward cycles of mudstone, sandstone, and conglomerate. Cu-Zn-Co-Mn stratiform ore deposits ("mantos") cap the conglomerate in each cycle, numbered 0, 1, 2, 3 and 4 (from top to bottom of section1). Sandstone samples were collected for U-Pb detrital zircon geochronology from four stratigraphic levels beneath a manto, including one each below mantos 1, 3 and 4, as well as two localities beneath manto 2. Additionally, one sample was collected above the gypsum. The sandstones are lithic feldspathic wackes derived from erosion of andesitic arc volcanic rocks, which generally lack zircon, so large DZ samples were collected. A field Wilfley table was constructed from local materials as a first step to concentrate heavy minerals, from 88 kg/sample to 16 kg/sample. The field-processed samples were further concentrated in the lab using standard zircon separation methods. Yields were excellent, 1,000 zircons per sample. We analyzed 315 zircons per sample by LA-ICPMS, using the Arizona LaserChron Center. DZ ages from the Boleo Formation range dominantly from Late Miocene through Early Cretaceous, with minor Paleozoic and Precambrian ages. However, the maximum depositional age of the formation is constrained by 40 Ar/39 Ar age of 9.42 +/- 0.29 Ma on underlying volcanic rocks2. Only 5 to 22 zircons per sample are less than 10 Ma, and of those, all stratigraphic levels are dominated mostly by 9 Ma zircons, except for the stratigraphically highest sample. Zircons from this form a coherent group of 3 with a TuffZirc age of 6.04 +/- 0.02 (75% confidence level). Thus the age of the top of the Boleo Formation appears to be well-constrained at 6 Ma, while the remainder of the section remains poorly constrained at 6-9 Ma. Future work will examine the provenance of the zircon in a Gulf of California tectonic framework. 1 Wilson 1995 USGS PP 273 2 Gutierrez et al., 2016 GSA Annual Mtg abstr.

Seasonal Patterns of Melatonin, Cortisol, and Progesterone Secretion in Female Lambs Raised Beneath a 500-KV Transmission Line

NASA Astrophysics Data System (ADS)

Lee, Jack Monroe, Jr.

There is ongoing controversy about the possibility of adverse biological effects from environmental exposures to electric and magnetic fields. These fields are produced by all electrical equipment and appliances including electrical transmission lines. The objective of this environmental science study was to investigate the possible effects of a high voltage transmission line on domestic sheep (Ovis aries L.), a species that can often be found near such lines. The study was primarily designed to determine whether a specific effect of electric and magnetic fields found in laboratory animals also occurs in livestock under natural environmental conditions. The effect is the ability of fields, at levels found in the environment, to significantly depress the normally high nocturnal concentrations of the pineal hormone-melatonin. Ten female Suffolk lambs were penned for 10 months directly beneath a 500-kV transmission line near Estacada, Oregon. Ten other lambs of the same type were penned in a control area away from the transmission line where electric and magnetic fields were at ambient levels. Serum melatonin was analyzed by radioimmunoassay (RIA) from 6618 blood samples collected at 0.5 to 3-hour intervals over eight 48-hour periods. Serum progesterone was analyzed by RIA from blood samples collected twice weekly. Serum cortisol was also assayed by RIA from the blood samples collected during the 48-hour samples. Results showed that lambs in both the control and line groups had the typical pattern of melatonin secretion consisting of low daytime and high nighttime serum concentrations. There were no statistically significant differences between groups in melatonin levels, or in the phase or duration of the nighttime melatonin elevation. Age at puberty and number of reproductive cycles also did not differ between groups. Serum cortisol showed a circadian rhythm with highest concentrations during the day. There were, however, no differences in cortisol concentrations between groups. Statistical analyses on other biological parameters revealed no differences between groups for body weight gain, wool growth, or behavior.

Magnetotelluric Investigation of Melt Storage Beneath Okmok Caldera, Alaska

NASA Astrophysics Data System (ADS)

Bennington, N. L.; Bedrosian, P.; Key, K.; Zelenak, G.

2015-12-01

Alaska accounts for nearly 99% of the seismic moment release within the US. Much of this is associated with the Aleutian volcanic arc, the most tectonically active region in North America, and an ideal location for studying arc magmatism. Okmok is an active volcano located in the central Aleutian arc, defined by a pair of nested, 10 km diameter calderas. The subdued topography of Okmok, relative to other Aleutian volcanoes, improves access and permits dense sampling within the caldera closer to the underlying magmatic system. Okmok volcano was selected as the site of study for this project due to frequent volcanic activity and the presence of a crustal magma reservoir as inferred from previous coarse resolution seismic studies. In June-July 2015, we carried out an amphibious geophysical field deployment at Okmok. Onshore work in and around the volcano included collection of an array of magnetotelluric (MT) stations and installation of a temporary, year-long seismic array. A ring of 3D offshore MT deployments made around the island augments the onshore array. An additional 2D tectonic-scale profile spans the trench, volcanic arc, and backarc. This new geophysical data will be used to gain a greater understanding of Aleutian arc melt generation, migration, and storage beneath an active caldera. We present results from the analysis of the newly collected amphibious 3D MT data. This data will be used to model the distribution and migration of melt within Okmok's crustal magma reservoir. Initial processing of the data shows strong MT signal levels, in particular from a geomagnetic storm that occurred from June 21-23, 2015. A companion abstract discussing the 2D tectonic scale MT profile, which constrains the mantle and deep crust beneath Okmok volcano, is discussed by Zelenak et al.

Summary and Preliminary Interpretation of Tritium and Dissolved Noble Gas Data from Site 300

DOE Office of Scientific and Technical Information (OSTI.GOV)

Visser, A.; Singleton, M.; Madrid, V.

2014-01-29

In October 2013, groundwater samples were collected from 10 wells from Site 300 and analyzed by the Environmental Radiochemistry Laboratory at Lawrence Livermore National Laboratory (LLNL). Groundwater samples were analyzed for groundwater age tracers: tritium, the helium isotope ratio of dissolved helium and the concentrations of dissolved noble gases (Helium, Neon, Argon, Krypton, and Xenon). A subset of the samples was also analyzed for excess nitrogen due to saturated zone denitrification. The age-dating data were used to evaluate the degree to which groundwater at a particular monitoring well was derived from pre-modern and/or modern sources. More specifically, the analyses canmore » be used to determine whether the recharge age of the groundwater beneath the site pre-dates anthropogenic activities at the site.« less

Present-day subglacial erosion efficiency inferred from sources and transport of glacial clasts in the North face of Mont Blanc

NASA Astrophysics Data System (ADS)

Mugnier, J. L.; Godon, C.; Buoncristiani, J. F.; Paquette, J. L.; Trouvé, E.

2012-04-01

The efficiency of erosional processes is classically considered from detrital composition at the outlet of a shed that reflects the rocks eroded within the shed. We adapt fluvial detrital thermochronology (DeCelles et al., 2004) and lithology (Attal and Lavé, 2006) methods to the subglacial streams of the north face of the Mont Blanc. The lithology of this area is composed by a ~303 Ma old granite intruded within an older poly metamorphic complex (orthogneisses). In this study,we use macroscopic criteria (~10 000 clasts) and Ur/Pb dating of zircons (~500 datings of sand grains) to determine the provenance of the sediment transported by the glacier and by the sub-glacial streams. Samples come from sediments collected around the glacier (above, below or laterally), from different bedrocks sources according to the surface flow lines and glacier characteristics (above or below the ELA; temperate or cold), and from different subglacial streams. A comparison between the proportion of granite and orthogneisses in these samples indicates that: 1) the supra load follows the flow lines of the glacier deduced from SAR images correlation and the displacement pattern excludes supra load mixing of the different sources; 2) the transport by the glacier does not mix the clasts issued from the sub-glacial erosion with the clasts issued from supraglacial deposition, except in the lower tongue where supraglacial streams and moulins move the supraglacial load from top to bottom; 3) the erosion rate beneath the glacier is very small: null beneath the cold ice but also very weak beneath the greatest part of the temperate glacier; the erosion increases significantly beneath the tongue, where supraglacial load incorporated at the base favors abrasion; 4) the glacial erosion rate beneath the tongue remains at least five time smaller than the erosion rate coming from non-glacial area. According to our results, we demonstrate that the glaciers of the Mont-Blanc north face protect the top of Europe from erosion. DeCelles et al., 2004, Earth and Planetary Science Letters, v. 227, p. 313-330. Attal and Lavé, 2006, Geol. Soc. Am. Spec. Publ. (S.D. Willett, N. Hovius, M.T. Brandon and D. Fisher, eds.), 398, p. 143-171.

Hydrogeologic setting and ground water flow beneath a section of Indian River Bay, Delaware

USGS Publications Warehouse

Krantz, David E.; Manheim, Frank T.; Bratton, John F.; Phelan, Daniel J.

2004-01-01

The small bays along the Atlantic coast of the Delmarva Peninsula (Delaware, Maryland, and Virginia) are a valuable natural resource, and an asset for commerce and recreation. These coastal bays also are vulnerable to eutrophication from the input of excess nutrients derived from agriculture and other human activities in the watersheds. Ground water discharge may be an appreciable source of fresh water and a transport pathway for nutrients entering the bays. This paper presents results from an investigation of the physical properties of the surficial aquifer and the processes associated with ground water flow beneath Indian River Bay, Delaware. A key aspect of the project was the deployment of a new technology, streaming horizontal resistivity, to map the subsurface distribution of fresh and saline ground water beneath the bay. The resistivity profiles showed complex patterns of ground water flow, modes of mixing, and submarine ground water discharge. Cores, gamma and electromagnetic-induction logs, and in situ ground water samples collected during a coring operation in Indian River Bay verified the interpretation of the resistivity profiles. The shore-parallel resistivity lines show subsurface zones of fresh ground water alternating with zones dominated by the flow of salt water from the estuary down into the aquifer. Advective flow produces plumes of fresh ground water 400 to 600 m wide and 20 m thick that may extend more than 1 km beneath the estuary. Zones of dispersive mixing between fresh and saline ground water develop on the upper, lower, and lateral boundaries of the the plume. the plumes generally underlie small incised valleys that can be traced landward to stream draining the upland. The incised valleys are filled with 1 to 2 m of silt and peat that act as a semiconfining layer to restrict the downward flow of salt water from the estuary. Active circulation of both the fresh and saline ground water masses beneath the bay is inferred from the geophysical results and supported by geochemical data.

Ground-Water Quality Beneath Irrigated Cropland of the Northern and Southern High Plains Aquifer, Nebraska and Texas, 2003-04

USGS Publications Warehouse

Stanton, Jennifer S.; Fahlquist, Lynne

2006-01-01

A study of the quality of ground water beneath irrigated cropland was completed for the northern and southern High Plains aquifer. Ground-water samples were collected from 30 water-table monitoring wells in the northern agricultural land-use (NAL) study area in Nebraska in 2004 and 29 water-table monitoring wells in the southern agricultural land-use (SAL) study area in Texas in 2003. The two study areas represented different agricultural and hydrogeologic settings. The primary crops grown in the NAL study area were corn and soybeans, and the primary crop in the SAL study area was cotton. Overall, pesticide and fertilizer application rates were larger in the NAL study area. Also, precipitation and recharge rates were greater in the NAL study area, and depths to water and evapotranspiration rates were greater in the SAL study area. Ground-water quality beneath irrigated cropland was different in the two study areas. Nitrate concentrations were larger and pesticide detections were more frequent in the NAL study area. Nitrate concentrations in NAL samples ranged from 1.96 to 106 mg/L (milligrams per liter) as nitrogen, with a median concentration of 10.6 mg/L. Water in 73 percent of NAL samples had at least one pesticide or pesticide degradate detected. Most of the pesticide compounds detected (atrazine, alachlor, metolachlor, simazine, and degradates of those pesticides) are applied to corn and soybean fields. Nitrate concentrations in SAL samples ranged from 0.96 to 21.6 mg/L, with a median of 4.12 mg/L. Water in 24 percent of SAL samples had at least one pesticide or pesticide degradate detected. The pesticide compounds detected were deethylatrazine (a degradate of atrazine and propazine), propazine, fluometuron, and tebuthiuron. Most of the pesticides detected are applied to cotton fields. Dissolved-solids concentrations were larger in the SAL area and were positively correlated with both nitrate and chloride concentrations, suggesting a combination of human and natural sources. Dissolved-solids concentrations in NAL samples ranged from 272 to 2,160 mg/L, with a median of 442 mg/L, and dissolved solids in SAL samples ranged from 416 to 3,580 mg/L, with a median of 814 mg/L.

Effects of land use on quality of water in stratified-drift aquifers in Connecticut

USGS Publications Warehouse

Grady, Stephen J.

1994-01-01

Human activities associated with agricultural, residential, commercial, and industrial land uses have affected the quality of water in the four stratified-drift aquifers examined in Connecticut. A study to evaluate quantitatively the effects of human activities, expressed as land use, on regional ground-water quality was initiated in 1984 as part of the U.S. Geological Survey's Toxic Waste-round-Water Contamination Program. Water-quality data were collected from 116 shallow stainless-steel wells installed beneath or immediately downgradient from seven types of land use areas within the Pootatuck, Pomperaug, Farmington, and Hockanum River valleys in Connecticut. Analysis of variance on the ranked concentrations of 21 largely uncensored or slightly censored constituents, and contingency-table analysis of the frequency of detection of 49 moderately to highly censored constituents indicate that 27 water-quality variables differ at the 0.05 level of significance for samples from at least one land use area. For most constituents, concentrations or detection frequencies are lowest in samples from the undeveloped areas, which characterize background water-quality conditions. The effect of agricultural land use on groundwater quality reflects tillage practices; tilled areas affect the water quality to a greater degree than do untilled areas. Twenty percent of the wells in the tilled agricultural areas yielded water with concentrations of nitrate plus nitrite-nitrogen exceeding 10 milligrams per liter. Atrazine detections in one-third of the wells in areas of tilled agricultural land use were significantly more common than in the undeveloped areas. Ground-water quality beneath sewered residential areas is more severely affected by inorganic and organic nonpoint-source contaminants than is water quality beneath unsewered residential areas. Median concentrations or detection frequencies of most physical properties and inorganic constituents of ground water are higher in sewered than in unsewered residential areas. Generally low concentrations (less than 1.0 microgram per liter) of one or more of 17 volatile organic compounds were detected in samples from 62 percent of the wells in the unsewered residential areas. Most of these compounds were detected in less than 10 percent of the ground-water samples from the unsewered residential areas, however, and consequently, their frequency of detections was not significantly different than in samples from other land use areas. The detection of chloroform in ground-water samples from 47 percent of the wells in the sewered residential areas is significantly higher than the frequency of detection of chloroform in samples from the undeveloped, tilled agricultural, and unsewered residential areas. The quality of ground water is adversely affected beneath commercial areas more so than beneath all other land use areas. Median concentrations of sodium (22.5 milligrams per liter), chloride (36 milligrams per liter), and dissolved solids (286 milligrams per liter) are highest in ground-water samples in commercial areas. Detections of tetrachloroethylene, trichloroethylene, and 1,2-transdichloroethylene were significantly more common in ground-water samples from the commercial areas than in samples from one or more of the other land use areas. Tetrachloroethylene was detected in water samples from 50 percent of the observation wells in the commercial areas at concentrations of up to 1,300 micrograms per liter. Trichloroethylene and 1,2-transdichloroethylene were found at concentrations of up to 20 and 55 micrograms per liter, respectively, in samples from more than 40 percent of the wells in the commercial areas. Although industrial areas occupy only a small part of each of the study areas, they have a disproportionately large effect on ground-water quality. One or more of 12 volatile organic compounds were detected in water samples from 91 percent of the observation wells in the industrial areas

Factors affecting the recovery of Legionella pneumophila serogroup 1 from cooling tower water systems.

PubMed

Lu, H F; Tsou, M F; Huang, S Y; Tsai, W C; Chung, J G; Cheng, K S

2001-09-01

A total of 20 water samples collected from the cooling towers at 20 different sites were analyzed under various conditions for the presence of Legionella pneumophila serogroup 1. A comparative assessment was performed to evaluate methods of sample collection (spray drops, beneath water at 20- to 40-cm depth, and water outlet), concentration (filtration and centrifugation), acid buffer treatment (no treatment, treatment for 3, 5, and 15 min), and CO2 incubation or candle jar incubation. The reduction in viable colonies and false negative rate were compared for the different factors. No quantitative differences in isolation of L. pneumophila serogroup 1 was found among samples collected from water at a depth of 20 to 40 cm, from water outlet, and from spray drops. Treatment in an acid buffer for 15 min significantly reduced the recovery rate, with a reduction in bacterial counts of about 40%, compared with a 3-min (12%) or a 5-min (25%) treatment. Acid buffer treatment for 3 or 5 min reduced the overgrowth of commensal flora. This treatment improved the selectivity but not the sensitivity for L. pneumophila serogroup 1. Colonies on plates incubated at 37 degrees C in a candle jar with a humidified atmosphere grew better than those incubated at 35 degrees C with 5% CO2. These results demonstrate that methods of sample collection, concentration, and incubation, but not collection site, can affect the isolation rate for L. pneumophila serogroup 1.

A Black Hills-Madison Aquifer origin for Dakota Aquifer groundwater in northeastern Nebraska.

PubMed

Stotler, Randy; Harvey, F Edwin; Gosselin, David C

2010-01-01

Previous studies of the Dakota Aquifer in South Dakota attributed elevated groundwater sulfate concentrations to Madison Aquifer recharge in the Black Hills with subsequent chemical evolution prior to upward migration into the Dakota Aquifer. This study examines the plausibility of a Madison Aquifer origin for groundwater in northeastern Nebraska. Dakota Aquifer water samples were collected for major ion chemistry and isotopic analysis ((18)O, (2)H, (3)H, (14)C, (13)C, (34)S, (18)O-SO(4), (87)Sr, (37)Cl). Results show that groundwater beneath the eastern, unconfined portion of the study area is distinctly different from groundwater sampled beneath the western, confined portion. In the east, groundwater is calcium-bicarbonate type, with delta(18)O values (-9.6 per thousand to -12.4 per thousand) similar to local, modern precipitation (-7.4 per thousand to -10 per thousand), and tritium values reflecting modern recharge. In the west, groundwater is calcium-sulfate type, having depleted delta(18)O values (-16 per thousand to -18 per thousand) relative to local, modern precipitation, and (14)C ages 32,000 to more than 47,000 years before present. Sulfate, delta(18)O, delta(2)H, delta(34)S, and delta(18)O-SO(4) concentrations are similar to those found in Madison Aquifer groundwater in South Dakota. Thus, it is proposed that Madison Aquifer source water is also present within the Dakota Aquifer beneath northeastern Nebraska. A simple Darcy equation estimate of groundwater velocities and travel times using reported physical parameters from the Madison and Dakota Aquifers suggests such a migration is plausible. However, discrepancies between (14)C and Darcy age estimates indicate that (14)C ages may not accurately reflect aquifer residence time, due to mixtures of varying aged water.

Nitrogen Cycling and Community Structure of Proteobacterial β-Subgroup Ammonia-Oxidizing Bacteria within Polluted Marine Fish Farm Sediments

PubMed Central

McCaig, Allison E.; Phillips, Carol J.; Stephen, John R.; Kowalchuk, George A.; Harvey, S. Martyn; Herbert, Rodney A.; Embley, T. Martin; Prosser, James I.

1999-01-01

A multidisciplinary approach was used to study the effects of pollution from a marine fish farm on nitrification rates and on the community structure of ammonia-oxidizing bacteria in the underlying sediment. Organic content, ammonium concentrations, nitrification rates, and ammonia oxidizer most-probable-number counts were determined in samples of sediment collected from beneath a fish cage and on a transect at 20 and 40 m from the cage. The data suggest that nitrogen cycling was significantly disrupted directly beneath the fish cage, with inhibition of nitrification and denitrification. Although visual examination indicated some slight changes in sediment appearance at 20 m, all other measurements were similar to those obtained at 40 m, where the sediment was considered pristine. The community structures of proteobacterial β-subgroup ammonia-oxidizing bacteria at the sampling sites were compared by PCR amplification of 16S ribosomal DNA (rDNA), using primers which target this group. PCR products were analyzed by denaturing gradient gel electrophoresis (DGGE) and with oligonucleotide hybridization probes specific for different ammonia oxidizers. A DGGE doublet observed in PCR products from the highly polluted fish cage sediment sample was present at a lower intensity in the 20-m sample but was absent from the pristine 40-m sample station. Band migration, hybridization, and sequencing demonstrated that the doublet corresponded to a marine Nitrosomonas group which was originally observed in 16S rDNA clone libraries prepared from the same sediment samples but with different PCR primers. Our data suggest that this novel Nitrosomonas subgroup was selected for within polluted fish farm sediments and that the relative abundance of this group was influenced by the extent of pollution. PMID:9872782

Hydrogeology and ground-water quality at a land reclamation site, Neshaminy State Park, Pennsylvania

USGS Publications Warehouse

Blickwedel, Ray S.; Linn, Jeff H.

1987-01-01

Analyses of ground-water samples collected after the first two sludge applications (120 tons per acre and 450 tons per acre), indicate that no significant change occurred in the chemistry of the samples from the Trenton gravel, whereas organic nitrogen increased temporarily in ground water from the dredge spoil 6 months after the larger of the two sludge applications, but quickly returned to background levels. The lack of chemical change with time in the ground water implies either that little of the more than 100 inches of precipitation that fell from April 1983 through March 1985 reached the water table or, more likely, that a mechanism exists beneath the soil- factory site that retards or prevents the downard migration of contaminants.

Japan signs Ocean Agreement

NASA Astrophysics Data System (ADS)

The Ocean Research Institute of the University of Tokyo and the National Science Foundation (NSF) have signed a Memorandum of Understanding for cooperation in the Ocean Drilling Program (ODP). The agreement calls for Japanese participation in ODP and an annual contribution of $2.5 million in U.S. currency for the project's 9 remaining years, according to NSF.ODP is an international project whose mission is to learn more about the formation and development of the earth through the collection and examination of core samples from beneath the ocean. The program uses the drillship JOIDES Resolution, which is equipped with laboratories and computer facilities. The Joint Oceanographic Institutions for Deep Earth Sampling (JOIDES), an international group of scientists, provides overall science planning and program advice regarding ODP's science goals and objectives.

Wilson Corners SWMU 001 2014 Annual Long Term Monitoring Report Kennedy Space Center, Florida

NASA Technical Reports Server (NTRS)

Langenbach, James

2015-01-01

This document presents the findings of the 2014 Long Term Monitoring (LTM) that was completed at the Wilson Corners site, located at the National Aeronautics and Space Administration (NASA) John F. Kennedy Space Center (KSC), Florida. The goals of the 2014 annual LTM event were to evaluate the groundwater flow direction and gradient and to monitor the vertical and downgradient horizontal extent of the volatile organic compounds (VOCs) in groundwater at the site. The LTM activities consisted of an annual groundwater sampling event in December 2014, which included the collection of water levels from the LTM wells. During the annual groundwater sampling event, depth to groundwater was measured and VOC samples were collected using passive diffusion bags (PDBs) from 30 monitoring wells. In addition to the LTM sampling, additional assessment sampling was performed at the site using low-flow techniques based on previous LTM results and assessment activities. Assessment of monitoring well MW0052DD was performed by collecting VOC samples using low-flow techniques before and after purging 100 gallons from the well. Monitoring well MW0064 was sampled to supplement shallow VOC data north of Hot Spot 2 and east of Hot Spot 4. Monitoring well MW0089 was sampled due to its proximity to MW0090. MW0090 is screened in a deeper interval and had an unexpected detection of trichloroethene (TCE) during the 2013 LTM, which was corroborated during the March 2014 verification sampling. Monitoring well MW0130 was sampled to provide additional VOC data beneath the semi-confining clay layer in the Hot Spot 2 area.

Determination of total mercury in whole-body fish and fish muscle plugs collected from the South Fork of the Humboldt River, Nevada, September 2005

USGS Publications Warehouse

May, Thomas W.; Brumbaugh, William G.

2007-01-01

This report presents the results of a study by the U.S. Geological Survey, done in cooperation with the U.S. Bureau of Reclamation, to determine mercury concentrations in whole-body fish and fish muscle plugs from the South Fork of the Humboldt River near Elko in the Te-Moak Indian Reservation. A single muscle plug was collected from beneath the dorsal fin area in each of the three whole-body fish samples. After homogenization and lyophilization of the muscle plugs and whole-body fish samples, mercury concentrations were determined with a direct mercury analyzer utilizing the process of thermal combustion-gold amalgamation atomic absorption spectroscopy. Mercury concentrations in whole-body fish ranged from 0.048 to 0.061 microgram per gram wet weight, and 0.061 to 0.082 microgram per gram wet weight in muscle plugs. All sample mercury concentrations were well below the U.S. Environmental Protection Agency's fish consumption advisory of 0.30 microgram per gram wet weight.

Food Fingerprinting: Characterization of the Ecuadorean Type CCN-51 of Theobroma cacao L. Using Microsatellite Markers.

PubMed

Herrmann, Luise; Felbinger, Christine; Haase, Ilka; Rudolph, Barbara; Biermann, Bernhard; Fischer, Markus

2015-05-13

The cocoa type "Colección Castro Naranjal 51" (CCN-51) is known for its resistance to specific climate conditions and its high yield, but it shows a weaker flavor profile and therefore is marketed as bulk cocoa. In a previous study, the two cocoa types Arriba and CCN-51 could easily be distinguished, but differences among the CCN-51 samples were observed. This was unexpected, as CCN-51 is reported to be a clone. To confirm whether CCN-51 is a pure clone, 10 simple sequence repeats (SSR) located on the nuclear genome were used to analyze various CCN-51 samples in comparison to the cocoa varieties Arriba and Criollo. As expected, there are differences in the SSR pattern among CCN-51, Arriba, and Criollo, but a variability within the CCN-51 sample set was detected as well. The previously described sequence variation in the chloroplast genome was confirmed by a variability in the microsatellite loci of the nuclear genome for a comprehensive cultivar collection of CCN-51 of both bean and leaf samples. In summary, beneath somaclonal variation, misidentification of plant collections and also sexual reproduction of CCN-51 can be suggested.

Size-specific composition of aerosols in the El Chichon volcanic cloud

NASA Technical Reports Server (NTRS)

Woods, D. C.; Chuan, R. L.

1983-01-01

A NASA U-2 research aircraft flew sampling missions in April, May, July, November, and December 1982 aimed at obtaining in situ data in the stratospheric cloud produced from the March-April 1982 El Chichon eruptions. Post flight analyses provided information on the aerosol composition and morphology. The particles ranged in size from smaller than 0.05 m to larger than 20 m diameter and were quite complex in composition. In the April, May, and July samples the aerosol mass was dominated by magmatic and lithic particles larger than about 3 m. The submicron particles consisted largely of sulfuric acid. Halite particles, believed to be related to a salt dome beneath El Chichon, were collected in the stratosphere in April and May. On the July 23 flight, copper-zinc oxide particles were collected. In July, November, and December, in addition to the volcanic ash and acid particles, carbon-rich particles smaller than about 0.1 m aerodynamic diameter were abundant.

Fluoroacetate content of some species of the toxic Australian plant genus, Gastrolobium, and its environmental persistence.

PubMed

Twigg, L E; King, D R; Bowen, L H; Wright, G R; Eason, C T

1996-01-01

Gas chromatography confirmed the relatively high concentrations of fluoroacetate found in toxic Gastrolobiums, a genus of indigenous Australian plants. Fluoroacetate concentration in these plants ranged from 0.1 to 3875 micrograms/g (ppm) dry weight, with young leaves and flowers containing the highest concentrations. However, there was considerable intrastand variation between individual plants of at least two species with coefficients of variation ranging from 94% to 129%. Despite the high concentrations of fluoroacetate in many species, only one of nine soil samples collected from beneath these plants contained fluoroacetate. None of the 16 water samples collected from nearby streams and catchment dams contained fluoroacetate. This suggests that fluoroacetate does not persist in this environment. Fluoroacetate was also found in the genus Nemcia, and very low levels of fluoroacetate (ng/g) were detected in the foodstuffs, tea and guar gum. The latter indicates that other plant species may produce biologically insignificant amounts of fluoroacetate.

Petrology and geochemistry of primitive lower oceanic crust from Pito Deep: Implications for the accretion of the lower crust at the Southern East Pacific Rise

USGS Publications Warehouse

Perk, N.W.; Coogan, L.A.; Karson, J.A.; Klein, E.M.; Hanna, H.D.

2007-01-01

A suite of samples collected from the uppermost part of the plutonic section of the oceanic crust formed at the southern East Pacific Rise and exposed at the Pito Deep has been examined. These rocks were sampled in situ by ROV and lie beneath a complete upper crustal section providing geological context. This is only the second area (after the Hess Deep) in which a substantial depth into the plutonic complex formed at the East Pacific Rise has been sampled in situ and reveals significant spatial heterogeneity in the plutonic complex. In contrast to the uppermost plutonic rocks at Hess Deep, the rocks studied here are generally primitive with olivine forsterite contents mainly between 85 and 88 and including many troctolites. The melt that the majority of the samples crystallized from was aggregated normal mid-ocean ridge basalt (MORB). Despite this high Mg# clinopyroxene is common despite model predictions that clinopyroxene should not reach the liquidus early during low-pressure crystallization of MORB. Stochastic modeling of melt crystallisation at various levels in the crust suggests that it is unlikely that a significant melt mass crystallized in the deeper crust (for example in sills) because this would lead to more evolved shallow level plutonic rocks. Similar to the upper plutonic section at Hess Deep, and in the Oman ophiolite, many samples show a steeply dipping, axis-parallel, magmatic fabric. This suggests that vertical magmatic flow is an important process in the upper part of the seismic low velocity zone beneath fast-spreading ridges. We suggest that both temporal and spatial (along-axis) variability in the magmatic and hydrothermal systems can explain the differences observed between the Hess Deep and Pito Deep plutonics. ?? Springer-Verlag 2007.

Environmental occurrence and shallow ground water detection of the antibiotic monensin from dairy farms

USGS Publications Warehouse

Watanabe, N.; Harter, T.H.; Bergamaschi, B.A.

2008-01-01

Pharmaceuticals used in animal feeding operations have been detected in various environmental settings. There is a growing concern about the impact on terrestrial and aquatic organisms and the development of antibiotic-resistant strains of microorganisms. Pharmaceutical use in milking cows is relatively limited compared with other livestock operations, except for the ionophore monensin, which is given to lactating cows as a feed. By weight, monensin can be the most significant antibiotic used in a dairy farm. This study investigates the potential of monensin to move from dairy operations into the surrounding ground water. Using two dairy farms in California as study sites, we twice collected samples along the environmental pathway - from flush lanes, lagoon waters, and shallow ground water beneath the dairies and beneath its associated manured fields. Monensin concentrations were determined using solid-phase extraction and liquid chromatography-tandem mass spectrometry with positive electrospray ionization. Monensin was detected in all of the flush lane and lagoon water samples. Theoretical maximum concentration estimated from the actual dosing rate and the theoretical excretion rate assuming no attenuation was one order of magnitude greater than observed concentrations, suggesting significant attenuation in the manure collection and storage system. Monensin was also detected, at levels ranging from 0.04 to 0.39 ??g L-1, in some of the ground water samples underneath the production area of the dairy but not from the adjacent manured fields. Concentrations in ground water immediately downgradient of the lagoons were one to two orders of magnitude lower than the concentrations detected in lagoons, suggesting attenuation in the subsurface. The data suggest the possibility of monensin transport into shallow (2-5 m) alluvial ground water from dairy management units, including manure storage lagoons and freestalls occupied by heifers, lactating cows, and dry cows. Copyright ?? 2008 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

Deciphering the Tectonic History of the Northern Transantarctic Mountains

NASA Astrophysics Data System (ADS)

Hansen, Samantha; Graw, Jordan; Brenn, Gregory; Kenyon, Lindsey; Park, Yongcheol; DuBay, Brian

2016-04-01

The Transantarctic Mountains (TAMs) are the largest non-compressional mountain range in the world, and their structure plays a key role in the climatic and tectonic development of Antarctica. While numerous uplift mechanisms for the TAMs have been proposed, there is little consensus on their origin. Over the past three years, we have operated a network of 15 broadband seismic stations within a previously unexplored portion of the northern TAMs. Using data collected by this array, we have undertaken numerous studies to further assess the crustal and lithospheric structure beneath the mountain range and to differentiate between competing origin models. Receiver functions indicate crustal thickening inland from the Ross Sea coast but comparable crustal thickness beneath the TAMs and the East Antarctic plateau, indicating little evidence for a substantial crustal root beneath the mountain range. Body and surface wave analyses show a pronounced low-velocity anomaly beneath Terror Rift, adjacent to the TAMs, and extending beneath Victoria Land in the upper mantle. Together, these findings support a thermally-buoyant source of uplift for the northern TAMs and broad flexure of the East Antarctic lithosphere.

Comet nucleus sample return mission

NASA Technical Reports Server (NTRS)

1983-01-01

A comet nucleus sample return mission in terms of its relevant science objectives, candidate mission concepts, key design/technology requirements, and programmatic issues is discussed. The primary objective was to collect a sample of undisturbed comet material from beneath the surface of an active comet and to preserve its chemical and, if possible, its physical integrity and return it to Earth in a minimally altered state. The secondary objectives are to: (1) characterize the comet to a level consistent with a rendezvous mission; (2) monitor the comet dynamics through perihelion and aphelion with a long lived lander; and (3) determine the subsurface properties of the nucleus in an area local to the sampled core. A set of candidate comets is discussed. The hazards which the spacecraft would encounter in the vicinity of the comet are also discussed. The encounter strategy, the sampling hardware, the thermal control of the pristine comet material during the return to Earth, and the flight performance of various spacecraft systems and the cost estimates of such a mission are presented.

Environmental conditions in the Namskaket Marsh Area, Orleans, Massachusetts: A summary of studies by the U.S. Geological Survey, 1989–2011

USGS Publications Warehouse

Weiskel, Peter K.; Barbaro, Jeffrey R.; DeSimone, Leslie A.

2016-09-23

The tidal creek sampling stations established in the 1990s were resampled in 2003–4 and 2010–11 to evaluate potential effects of the treated wastewater plume on creek water quality. The annual medians of the 2011 biweekly nitrate and total dissolved nitrogen concentrations were determined for each station and compared to the annual medians of biweekly samples for the baseline years 1994, 1995, and 1996. At all stations, the 2011 median nitrate concentrations were within the range of medians for the 3 baseline years. A similar result was obtained for total dissolved nitrogen. We conclude that the 2011 creek samples, collected approximately 8 years after the shallow plume segment was first detected beneath the marsh, do not show evidence of elevated nitrate or total dissolved nitrogen concentrations attributable to discharge of either the shallow or deep segments of the treated wastewater plume.

Differences in plantar loading between training shoes and racing flats at a self-selected running speed.

PubMed

Wiegerinck, Johannes I; Boyd, Jennifer; Yoder, Jordan C; Abbey, Alicia N; Nunley, James A; Queen, Robin M

2009-04-01

The purpose of this study was to examine the difference in plantar loading between two different running shoe types. We hypothesized that a higher maximum force, peak pressure, and contact area would exist beneath the entire foot while running in a racing flat when compared to a training shoe. 37 athletes (17 male and 20 female) were recruited for this study. Subjects had no history of lower extremity injuries in the past six months, no history of foot or ankle surgery within the past 3 years, and no history of metatarsal stress fractures. Subjects had to be physically active and run at least 10 miles per week. Each subject ran on a 10m runway 7 times wearing two different running shoe types, the Nike Air Pegasus (training shoe) and the Nike Air Zoom Katana IV (racing flat). A Pedar-X in-shoe pressure measurement system sampling at 50Hz was used to collect plantar pressure data. Peak pressure, maximum force, and contact area beneath eight different anatomical regions of the foot as well as beneath the total foot were obtained. The results of this study demonstrated a significant difference between training shoes and racing flats in terms of peak pressure, maximum force, and contact area. The significant differences measured between the two shoes can be of importance when examining the influence of shoe type on the occurrence of stress fractures in runners.

Flow and geochemistry of groundwater beneath a back-barrier lagoon: The subterranean estuary at Chincoteague Bay, Maryland, USA

USGS Publications Warehouse

Bratton, J.F.; Böhlke, J.K.; Krantz, D.E.; Tobias, C.R.

2009-01-01

To better understand large-scale interactions between fresh and saline groundwater beneath an Atlantic coastal estuary, an offshore drilling and sampling study was performed in a large barrier-bounded lagoon, Chincoteague Bay, Maryland, USA. Groundwater that was significantly fresher than overlying bay water was found in shallow plumes up to 8??m thick extending more than 1700??m offshore. Groundwater saltier than bay surface water was found locally beneath the lagoon and the barrier island, indicating recharge by saline water concentrated by evaporation prior to infiltration. Steep salinity and nutrient gradients occur within a few meters of the sediment surface in most locations studied, with buried peats and estuarine muds acting as confining units. Groundwater ages were generally more than 50??years in both fresh and brackish waters as deep as 23??m below the bay bottom. Water chemistry and isotopic data indicate that freshened plumes beneath the estuary are mixtures of water originally recharged on land and varying amounts of estuarine surface water that circulated through the bay floor, possibly at some distance from the sampling location. Ammonium is the dominant fixed nitrogen species in saline groundwater beneath the estuary at the locations sampled. Isotopic and dissolved-gas data from one location indicate that denitrification within the subsurface flow system removed terrestrial nitrate from fresh groundwater prior to discharge along the western side of the estuary. Similar situations, with one or more shallow semi-confined flow systems where groundwater geochemistry is strongly influenced by circulation of surface estuary water through organic-rich sediments, may be common on the Atlantic margin and elsewhere.

Characterizing 2-D snow stratigraphy in forests based on high-resolution snow penetrometry

NASA Astrophysics Data System (ADS)

Teich, M.; Loewe, H.; Jenkins, M. J.; Schneebeli, M.

2016-12-01

Snow stratigraphy, the characteristic layering within a seasonal snowpack, has important implications for snow remote sensing, hydrology and avalanches. Forests modify snowpack properties through interception of falling snow by tree crowns, the reduction of near-surface wind speeds, and changes to the energy balance beneath and around trees leading to a highly variable stratigraphy in space and time. The lack of snowpack observations in forests limits our ability to understand the spatio-temporal evolution of snow stratigraphy as a function of forest structure and to observe snowpack response to changes in forest cover. We examined the snowpack in field campaigns using the SnowMicroPen (SMP) under tree canopies in an Engelmann spruce forest in the central Rocky Mountains in Utah, USA. Data were collected in plots beneath canopies of undisturbed, bark beetle-disturbed and salvage logged forest stands, and a non-forested meadow. In 2015 weekly-repeated SMP penetration measurements were taken along 10 m transects at 0.3 m intervals. In the winter of 2016 bi-weekly measurements were collected along 20 m transects every 0.5 m. Using a statistical model, we derived 2-D snow density profiles as a measure of stratigraphy. The small-scale patterns in snow density revealed a more heterogeneous stratigraphy in undisturbed dense stands and also beneath bark beetle-disturbed forest. In contrast, snow stratigraphy was more homogeneous in the harvested plot despite standing small diameter trees and woody debris with effective heights up to 95 cm. As expected, snow depth and layering in non-forested plots varied only slightly over the small spatial extent sampled. Observed patterns changed throughout the snow season dependent upon snow and meteorological conditions. The results contribute to the general understanding of forest-snowpack interactions at high spatial resolution, and can be used to validate snowpack and microwave models for avalanche formation processes and SWE retrieval in forests.

Developments of Finite-Frequency Seismic Theory and Applications to Regional Tomographic Imaging

DTIC Science & Technology

2009-01-31

banana -doughnut” sensitivity kernels of teleseismic body waves to image the crust and mantle beneath eastern Eurasia. We have collected and processed...In this project, we use the “ banana -doughnut” sensitivity kernels of teleseismic body waves to image the crust and mantle beneath eastern Eurasia...replaced body-wave ray paths with “ banana -doughnut” sensitivity kernels calculated in 1D (Dahlen et al., 2000; Hung et al., 2000; Zhao et al., 2000

Groundwater geochemical and selected volatile organic compound data, Operable Unit 1, Naval Undersea Warfare Center, Division Keyport, Washington, July 2013

USGS Publications Warehouse

Huffman, Raegan L.

2014-01-01

Previous investigations indicate that concentrations of chlorinated volatile organic compounds (CVOCs) are substantial in groundwater beneath the 9-acre former landfill at Operable Unit 1, Naval Undersea Warfare Center, Division Keyport, Washington. The U.S. Geological Survey has continued to monitor groundwater geochemistry to ensure that conditions remain favorable for contaminant biodegradation as specified in the Record of Decision for the site. This report presents groundwater geochemical and selected CVOC data collected at Operable Unit 1 by the U.S. Geological Survey during July 9–18, 2013, in support of longterm monitoring for natural attenuation. Groundwater samples were collected from 13 wells and 9 piezometers, as well as from 10 shallow groundwater passive-diffusion sampling sites in the nearby marsh. Samples from all wells and piezometers were analyzed for oxidation-reduction (redox) sensitive constituents and dissolved gases. Samples from all piezometers and four wells also were analyzed for CVOCs, as were all samples from the passive-diffusion sampling sites. In 2013, concentrations of redox-sensitive constituents measured at all wells and piezometers were consistent with those measured in previous years, with dissolved oxygen concentrations at all except an upgradient well 0.2 milligrams per liter or less; little to no detectable nitrate; abundant dissolved manganese, iron, and methane; and commonly detected sulfide. In the upper aquifer of the northern plantation in 2013, CVOC concentrations at all piezometers were similar to those measured in previous years, and concentrations of the reductive dechlorination byproducts ethane and ethene were slightly lower or the same as concentrations measured in 2012. In the upper aquifer of the southern plantation, CVOC concentrations measured in piezometers during 2013 continued to be variable as in previous years, and often very high, and reductive dechlorination byproducts were detected in two of the three wells and in all but one piezometer. Beneath the marsh adjacent to the southern plantation, chloroethene concentrations measured in 2013 continued to vary spatially and temporaly, and also were very high. Total CVOC concentrations, at what have been historically the most contaminated passive-diffusion sampler sites (S-4, S-4B, S-5, and S-5B) remained elevated. For the intermediate aquifer in 2013, concentrations of reductive dechlorination byproducts ethane and ethene and CVOCs were consistent with those measured in previous years.

Groundwater geochemical and selected volatile organic compound data, Operable Unit 1, Naval Undersea Warfare Center, Division Keyport, Washington, June and September 2014

USGS Publications Warehouse

Huffman, Raegan L.

2015-01-01

Previous investigations indicate that concentrations of chlorinated volatile organic compounds (CVOCs) are substantial in groundwater beneath the 9-acre former landfill at Operable Unit 1, Naval Undersea Warfare Center, Division Keyport, Washington. The U.S. Geological Survey has continued to monitor groundwater geochemistry to ensure that conditions remain favorable for contaminant biodegradation at the site. This report presents groundwater geochemical and selected CVOC data collected at Operable Unit 1 by the U.S. Geological Survey during June 23–25 and September 4, 2014, in support of long-term monitoring for natural attenuation. Groundwater samples were collected from 13 wells and 9 piezometers, as well as from 10 shallow groundwater passive-diffusion sampling sites in the nearby marsh. Samples from all wells and piezometers were analyzed for oxidation-reduction (redox) sensitive constituents and dissolved gases. Samples from all piezometers and four wells also were analyzed for CVOCs, as were all samples from the passive-diffusion sampling sites. In 2014, concentrations of redox-sensitive constituents measured at all wells and piezometers were consistent with those measured in previous years, with dissolved oxygen concentrations all less than 1 milligram per liter; little to no detectable nitrate; abundant dissolved manganese, iron, and methane; and commonly detected sulfide. In the upper aquifer of the northern plantation in 2014, CVOC concentrations at all piezometers were similar to those measured in previous years, and concentrations of the reductive dechlorination byproducts ethane and ethene were slightly lower or the same as concentrations measured in 2013. In the upper aquifer of the southern plantation, CVOC concentrations measured in piezometers during 2014 continued to be variable as in previous years, often high, and reductive dechlorination byproducts were detected in one of the three wells and in all but two piezometers. Beneath the marsh adjacent to the southern plantation, chloroethene concentrations measured in 2014 continued to vary spatially and temporally, and were high. Trends for total CVOC concentration continued to increase at the historically most contaminated passive‑diffusion sampler sites (S-4, S-4B, and S-5). For the intermediate aquifer in 2014, concentrations of reductive dechlorination byproducts ethane and ethene and CVOCs were consistent with those measured in previous years.

In situ silicone tube microextraction: a new method for undisturbed sampling of root-exuded thiophenes from marigold (Tagetes erecta L.) in soil.

PubMed

Mohney, Brian K; Matz, Tricia; Lamoreaux, Jessica; Wilcox, David S; Gimsing, Anne Louise; Mayer, Philipp; Weidenhamer, Jeffrey D

2009-11-01

The difficulties of monitoring allelochemical concentrations in soil and their dynamics over time have been a major barrier to testing hypotheses of allelopathic effects. Here, we evaluate three diffusive sampling strategies that employ polydimethylsiloxane (PDMS) sorbents to map the spatial distribution and temporal dynamics of root-exuded thiophenes from the African marigold, Tagetes erecta. Solid phase root zone extraction (SPRE) probes constructed by inserting stainless steel wire into PDMS tubing were used to monitor thiophene concentrations at various depths beneath marigolds growing in PVC pipes. PDMS sheets were used to map the distribution of thiophenes beneath marigolds grown in thin glass boxes. Concentrations of the two major marigold thiophenes measured by these two methods were extremely variable in both space and time. Dissection and analysis of roots indicated that distribution of thiophenes in marigold roots also was quite variable. A third approach used 1 m lengths of PDMS microtubing placed in marigold soil for repeated sampling of soil without disturbance of the roots. The two ends of the tubing remained out of the soil so that solvent could be washed through the tubing to collect samples for HPLC analysis. Unlike the other two methods, initial experiments with this approach show more uniformity of response, and suggest that soil concentrations of marigold thiophenes are affected greatly even by minimal disturbance of the soil. Silicone tube microextraction gave a linear response for alpha-terthienyl when maintained in soils spiked with 0-10 ppm of this thiophene. This method, which is experimentally simple and uses inexpensive materials, should be broadly applicable to the measurement of non-polar root exudates, and thus provides a means to test hypotheses about the role of root exudates in plant-plant and other interactions.

Groundwater geochemical and selected volatile organic compound data, Operable Unit 1, Naval Undersea Warfare Center, Division Keyport, Washington, June 2009

USGS Publications Warehouse

Huffman, R.L.; Dinicola, R.S.

2011-01-01

Previous investigations indicate that natural attenuation and biodegradation of chlorinated volatile organic compounds (VOCs) are substantial in groundwater beneath the 9-acre former landfill at Operable Unit 1 (OU 1), Naval Undersea Warfare Center, Division Keyport, Washington. Phytoremediation combined with ongoing natural attenuation processes was the preferred remedy selected by the U.S. Navy, as specified in the Record of Decision for the site. The U.S. Navy planted two hybrid poplar plantations on the landfill in spring 1999 to remove and to control the migration of chlorinated VOCs in shallow groundwater. The U.S. Geological Survey (USGS) has continued to monitor groundwater geochemistry to ensure that conditions remain favorable for contaminant biodegradation as specified in the Record of Decision. This report presents groundwater geochemical and selected VOC data collected at OU 1 by the USGS during June 15-17, 2009, in support of long-term monitoring for natural attenuation. For 2009, groundwater samples were collected from 13 wells and 9 piezometers. Samples from all wells and piezometers were analyzed for redox sensitive constituents, and samples from 10 of 18 upper-aquifer wells and piezometers and 3 of 4 intermediate-aquifer wells also were analyzed for chlorinated VOCs. Concentrations of redox sensitive constituents measured in 2009 were consistent with previous years, with dissolved hydrogen (H2) concentrations ranging from less than 0.1 to 1.8 nanomolar (nM), dissolved oxygen concentrations all at 0.6 milligram per liter or less; little to no detectable nitrate; abundant dissolved manganese, iron, and methane; and commonly detected sulfide. The reductive declorination byproducts-methane, ethane, and ethene-were not detected in samples collected from the upgradient wells in the landfill or the upper aquifer beneath the northern phytoremediation plantation. Chlorinated VOC concentrations in 2009 at most piezometers were similar to or slightly less than chlorinated VOC concentrations measured in previous years. In 2009, concentrations of reductive dechlorination byproducts ethane and ethene were less than those measured in 2008 at most northern plantation wells and piezometers. For the upper aquifer beneath the southern phytoremediation plantation, chlorinated VOC concentrations in 2009 at the piezometers were extremely high and continued to vary considerably over space and between years. At piezometer P1-9, the total chlorinated VOC concentration increased from 25,000 micrograms per liter in 2008 to more than 172,000 micrograms per liter in 2009. At piezometer P1-7 in 2009, the concentrations of trichloroethene and cis-1,2-dichloroethene (cis-DCE) were the highest to date. The reductive dechlorination byproducts ethane and ethene were detected at all wells and piezometers in the southern plantation with the exception of piezometer P1-8, although the measured concentrations were not consistently high. For the intermediate aquifer, concentrations of redox sensitive constituents and VOCs in 2009 at wells MW1-25, MW1-28, and MW1-39 were consistent with concentrations measured in previous years. Concentrations of the reductive dechlorination byproducts ethane and ethene at wells MW1-25 and MW1-28 were equal to or greater than previously measured concentrations.

Groundwater geochemical and selected volatile organic compound data, Operable Unit 1, Naval Undersea Warfare Center, Division Keyport, Washington, June 2011

USGS Publications Warehouse

Huffman, Raegan L.; Frans, L.M.

2012-01-01

Previous investigations indicate that concentrations of chlorinated volatile organic compounds are substantial in groundwater beneath the 9-acre former landfill at Operable Unit 1, Naval Undersea Warfare Center, Division Keyport, Washington. Phytoremediation combined with ongoing natural attenuation processes was the preferred remedy selected by the U.S. Navy, as specified in the Record of Decision for the site. The U.S. Navy planted two hybrid poplar plantations on the landfill in spring 1999 to remove and to control the migration of chlorinated volatile organic compounds in shallow groundwater. The U.S. Geological Survey has continued to monitor groundwater geochemistry to ensure that conditions remain favorable for contaminant biodegradation as specified in the Record of Decision. This report presents groundwater geochemical and selected volatile organic compound data collected at Operable Unit 1 by the U.S. Geological Survey during June 20-22, 2011, in support of long-term monitoring for natural attenuation. In 2011, groundwater samples were collected from 13 wells and 9 piezometers. Samples from all wells and piezometers were analyzed for redox sensitive constituents and dissolved gases, and samples from 5 of 13 wells and all piezometers also were analyzed for chlorinated volatile organic compounds. Concentrations of redox sensitive constituents measured in 2011 were consistent with previous years, with dissolved oxygen concentrations all at 0.4 milligram per liter or less; little to no detectable nitrate; abundant dissolved manganese, iron, and methane; and commonly detected sulfide. The reductive declorination byproducts - methane, ethane, and ethene - were either not detected in samples collected from the upgradient wells in the landfill and the upper aquifer beneath the northern phytoremediation plantation or were detected at concentrations less than those measured in 2010. Chlorinated volatile organic compound concentrations in 2011 at most piezometers were similar to or slightly less than chlorinated volatile organic compound concentrations measured in previous years. For the upper aquifer beneath the southern phytoremediation plantation, chlorinated volatile organic compound concentrations in 2011 in groundwater from the piezometers were extremely high and continued to vary considerably over space and between years. At piezometer P1-9, the total chlorinated volatile organic compound concentrations increased from 9,500 micrograms per liter in 2010 to more than 44,000 micrograms per liter in 2011. Total chlorinated volatile organic compound concentrations decreased at piezometers P1-6, P1-7, and P1-10 compared to the concentrations measured in 2010. One or both of the reductive dechlorination byproducts ethane and ethene were detected at all piezometers and three of the four wells in the southern plantation. For the intermediate aquifer, concentrations of redox sensitive constituents and chlorinated volatile organic compounds in 2011 were consistent with concentrations measured in previous years, with the exception of notable decreases in sulfate and chloride concentrations at well MW1-28. Concentrations of the reductive dechlorination byproducts ethane and ethene decreased at wells MW1-25 and MW1-28 compared to previously measured concentrations.

Prevalence of Dermanyssus and Ornithonyssus species of mites in poultry farms of Vikarabad area of Hyderabad.

PubMed

Sreenivasa Murthy, G S; Panda, Rasmita

2016-12-01

The common blood feeder mites of poultry are from the genera Dermanyssus and Ornithonyssus . Their presence are problematic for the producers either through potential direct effects on weight gain, egg production or sperm production in roosters or as nuisance pests on workers. They also cause anaemia in birds and play a vector role for several human and animal diseases. Five poultry farm buildings of Vikarabad area of Rangareddy district were visited. Samples were collected from a variety of sites, including beneath feed troughs, inside cage fittings and fastening clips, under egg conveyer belts and under manure belts. Heavily mite infested feathers were plucked from three to five individual birds and kept in closed plastic covers. Samples were processed and mounted permanently by using DPX and species differentiation was done. Besides this litter materials and soil samples from the farm were also collected. Massive mixed infestations of Dermanyssus and Ornithonyssus mites were found. The morphological characters provided here can be considered as a practical tool for species differentiation and as these blood feeder mites were most prevalent and important pests of poultry, public health aspects of these parasites should be considered.

Trees and Weathering: Using Soil Petrographic and Chemical Analyses to Compare the Relative Weathering Effects of Gymnosperms and Angiosperms in the Cascade Mountains of Washington State, USA

NASA Astrophysics Data System (ADS)

Andrews, M. Y.; Ague, J. J.; Berner, R. A.

2006-12-01

Knowledge of the long-term carbon cycle and its control on atmospheric carbon dioxide levels over the Phanerozoic is crucial to understanding the impending dynamics of contemporary anthropogenic carbon contributions to the atmosphere. One aspect of the long-term carbon cycle that is poorly understood is the role of large vascular plants (trees) in contributing to the chemical weathering of silicate minerals. In particular, little is known about the differences in weathering rates between gymnosperms and angiosperms and how these dissimilarities may have impacted the carbon cycle subsequent to the evolution of angiosperm trees in the Mesozoic. One approach to evaluating these potential differences in weathering is to examine and quantitatively compare the chemistry and petrology of the soil mineral constituents from beneath modern groves of each broad tree type, where the groves have been subject to nearly identical environmental and geological conditions. This particular study focuses on field samples collected along transects through adjacent groves of angiosperms and gymnosperms in the Cascade Mountains of Washington State. Preliminary data demonstrate a significant difference in the soil texture and composition beneath the two types of trees. While soil at each field site has been generated from a homogeneous parent material, and subjected to similar inorganic environmental phenomena, soil density, particle size, and organic content vary across the transects. Soils beneath the angiosperms are denser and have a more clay-like texture, while soils beneath the gymnosperms are more organic-rich and have a sandy texture. Additional macroscopic and microscopic differences in the chemistry and petrology of these soils will illuminate the varied impacts these trees have on the silicate minerals in their immediate environment, and therefore lend insight into the potential impact these groups of organisms have had on the long-term carbon cycle over the past five hundred million years.

Occurrence of the saw-whet owl in Florida

USGS Publications Warehouse

Lesser, F.H.; Stickley, A.R.

1967-01-01

On 31 October 1965 at 1000 hours we observed and collected a Saw-whet Owl (Aegolius acadicus) in adult plumage and in apparently good physical condition at Ponte Vedra, St. Johns County, Florida. The bird flew from beneath a truck to a cross beam in a garage adjoining a large, fresh-water, wooded swamp dominated by cabbage palms (Sabal palmetto). We found a regurgitated pellet and a freshly killed, partially eaten cotton mouse (Peromyscus gossypinus) beneath the truck. The bird was sent to Henry M. Stevenson for deposit in Florida State University Museum, Tallahassee (specimen no. 4092b). Dr. Stevenson found that the skull had been shattered and the gonads destroyed in collecting. Total length (before skinning) was 210 mm.

Occurrence of fungicides and other pesticides in surface water, groundwater, and sediment from three targeted-use areas in the United States, 2009

USGS Publications Warehouse

Orlando, James L.; Smalling, Kelly L.; Reilly, Timothy J.; Boehlke, Adam; Meyer, Michael T.; Kuivila, Kathryn

2013-01-01

Surface-water, groundwater, and suspended- and bedsediment samples were collected in three targeted-use areas in the United States where potatoes were grown during 2009 and analyzed for an extensive suite of fungicides and other pesticides by gas chromatograph/mass spectrometry and liquid chromatography with tandem mass spectrometry. Fungicides were detected in all environmental matrices sampled during the study. The most frequently detected fungicides were azoxystrobin, boscalid, chlorothalonil, and pyraclostrobin. Other pesticides that were detected frequently included amino phosphonic acid (AMPA), atrazine, metolaclor, and the organochlorine insecticide p,p’-DDT and its degradates p,p’-DDD and p,p’-DDE. A greater number of pesticides were detected in surface water relative to the other environmental matrices sampled, and at least one pesticide was detected in 62 of the 63 surfacewater samples. The greatest numbers of pesticides and the maximum observed concentrations for most pesticides were measured in surface-water samples from Idaho. In eight surface- water samples (six from Idaho and two from Wisconsin), concentrations of bifenthrin, metolachlor, or malathion exceeded U.S. Environmental Protection Agency freshwater aquatic-life benchmarks for chronic toxicity to invertebrates. Thirteen pesticides, including seven fungicides, were detected in groundwater samples. Shallow groundwater samples collected beneath recently harvested potato fields contained more pesticides and had higher concentrations of pesticides than samples collected from other groundwater sources sampled during the study. Generally, pesticide concentrations were lower in groundwater samples than in surfacewater or sediment samples, with the exception of the fungicide boscalid, which was found to have its highest concentration in a shallow groundwater sample collected in Wisconsin. Thirteen pesticides, including four fungicides, were detected in suspended-sediment samples. The most frequently detected compounds were the fungicides boscalid, pyraclostrobin, and zoxamide, and the degradates p,p’-DDD and p,p’-DDE. Twenty pesticides, including six fungicides, were detected in bed-sediment samples. The most frequently detected compounds were pyraclostrobin, p,p’-DDT, p,p’-DDD, and p,p’-DDE.

Testing the concept of drift shadow at Yucca Mountain, Nevada

USGS Publications Warehouse

Paces, J.B.; Neymark, L.A.; Ghezzehei, T.; Dobson, P.F.

2006-01-01

If proven, the concept of drift shadow, a zone of reduced water content and slower ground-water travel time beneath openings in fractured rock of the unsaturated zone, may increase performance of a proposed geologic repository for high-level radioactive waste at Yucca Mountain, To test this concept under natural-flow conditions present in the proposed repository horizon, isotopes within the uranium-series decay chain (uranium-238, uranium-234, and thorium-230, or 238U-234U-230Th) have been analyzed in samples of rock from beneath four naturally occurring lithophysal cavities. All rock samples show 234U depletion relative to parent 238U indicating varying degrees of water-rock interaction over the past million years. Variations in 234U/238U activity ratios indicate that depletion of 234U relative to 238U can be either smaller or greater in rock beneath cavity floors relative to rock near cavity margins. These results are consistent with the concept of drift shadow and with numerical simulations of meter-scale spherical cavities in fractured tuff. Differences in distribution patterns of 234U/ 238U activity ratios in rock beneath the cavity floors are interpreted to reflect differences in the amount of past seepage into lithophysal cavities, as indicated by the abundance of secondary mineral deposits present on the cavity floors.

Detection of fresh ground water and a contaminant plume beneath Red Brook Harbor, Cape Cod, Massachusetts, 2000

USGS Publications Warehouse

McCobb, Timothy D.; LeBlanc, Denis R.

2002-01-01

Trichloroethene and tetrachloroethene were detected in ground water in a vertical interval from about 68 to 176 feet below sea level beneath the shoreline where the contaminant plume emanating from a capped landfill on the Massachusetts Military Reservation intersects Red Brook Harbor. The highest concentrations at the shoreline, about 15 micrograms per liter of trichloroethene and 1 microgram per liter of tetrachloroethene, were measured in samples from one well at about 176 feet below sea level. The concentrations of nutrients, such as nitrate and ammonium, and trace metals, such as iron and manganese, in these same samples are typical of uncontaminated ground water on Cape Cod. Fresh ground water (bulk electrical conductance less than 100 millisiemens per meter) is present beneath the harbor at 40 of 48 locations investigated within about 250 feet of the shoreline. Fresh ground water also was detected at one location approximately 450 feet from shore. The harbor bottom consists of soft sediments that range in thickness from 0 to greater than 20 feet and overlie sandy aquifer materials. Trichloroethene was detected at several locations in fresh ground water from the sandy aquifer materials beneath the harbor. The highest trichloroethene concentration, about 4.5 micrograms per liter, was measured about 450 feet from shore.

Characteristics and processing of seismic data collected on thick, floating ice: Results from the Ross Ice Shelf, Antarctica

USGS Publications Warehouse

Beaudoin, Bruce C.; ten Brink, Uri S.; Stern, Tim A.

1992-01-01

Coincident reflection and refraction data, collected in the austral summer of 1988/89 by Stanford University and the Geophysical Division of the Department of Scientific and Industrial Research, New Zealand, imaged the crust beneath the Ross Ice Shelf, Antarctica. The Ross Ice Shelf is a unique acquisition environment for seismic reflection profiling because of its thick, floating ice cover. The ice shelf velocity structure is multilayered with a high velocity‐gradient firn layer constituting the upper 50 to 100 m. This near surface firn layer influences the data character by amplifying and frequency modulating the incoming wavefield. In addition, the ice‐water column introduces pervasive, high energy seafloor, intra‐ice, and intra‐water multiples that have moveout velocities similar to the expected subseafloor primary velocities. Successful removal of these high energy multiples relies on predictive deconvolution, inverse velocity stack filtering, and frequency filtering. Removal of the multiples reveals a faulted, sedimentary wedge which is truncated at or near the seafloor. Beneath this wedge the reflection character is diffractive to a two‐way traveltime of ∼7.2 s. At this time, a prominent reflection is evident on the southeast end of the reflection profile. This reflection is interpreted as Moho indicating that the crust is ∼21-km thick beneath the profile. These results provide seismic evidence that the extensional features observed in the Ross Sea region of the Ross Embayment extend beneath the Ross Ice Shelf.

Investigation of sterols as potential biomarkers for the detection of pig (S. s. domesticus) decomposition fluid in soils.

PubMed

von der Lühe, Barbara; Dawson, Lorna A; Mayes, Robert W; Forbes, Shari L; Fiedler, Sabine

2013-07-10

This study was carried out to evaluate the potential of using cholesterol and coprostanol, as indicators for the detection of decomposition fluid of buried pigs (S. s. domesticus) in soils. In May 2007, four pig carcasses (∼35kg) were buried in shallow graves (∼40 cm depth) at the University of Ontario Institute of Technology in Canada. Two pigs were exhumed after three months (Pig 1, Pig 2) and six months (Pig 3, Pig 4) post burial. Soil samples were collected beneath the pig carcasses (∼40cm depth) and from grave walls (∼15-20 cm depth) as well as from a parallel control site. Coprostanol and cholesterol were extracted from soils, purified with solid phase extraction (SPE) and analysed with gas chromatography/mass spectrometry (GC/MS). A significant increase in cholesterol concentrations (p<0.05) and amounts of coprostanol were detected in soil located beneath the pig carcasses after three months of burial. It is assumed that during the putrefaction and liquefaction stages of decomposition pig fluid which contains cholesterol and coprostanol is released into the underlying soil. Therefore, cholesterol and coprostanol could be used as potential biomarkers to detect the presence of decomposition fluid three months after burial under comparable soil and environmental conditions. Further research is suggested for additional soil sampling before and after three months to investigate the abundance of these and other sterols. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Distribution and Migration of Ordnance-Related Compounds and Oxygen and Hydrogen Stable Isotopes in Ground Water near Snake Pond, Sandwich, Massachusetts

USGS Publications Warehouse

LeBlanc, Denis R.; Massey, Andrew J.; Cochrane, Jessica J.; King, Jonathan H.; Smith, Kirk P.

2008-01-01

Explosive compounds, such as RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) and HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine), and the propellant compound perchlorate are present in ground water near Snake Pond, a ground-water flow-through glacial kettle pond in the glacial sand and gravel aquifer on western Cape Cod near Camp Edwards on the Massachusetts Military Reservation. The contaminants originate from the J-3 Range ordnance training and testing area. Ground-water samples were collected at 10 sites near the pond to determine the paths of the contaminants as they underflow or completely or partially discharge into the pond. Water-quality profiles were developed for sites on opposite ends of a 200-foot-long intermittent island near the northern, upgradient end of the pond by collecting water samples from two temporary drive-point borings. RDX was detected at both locations between 60 and 90 feet below the pond level. The highest RDX concentration was 0.99 micrograms per liter. Perchlorate was detected at only one location on the island, between 95 and 100 feet below the pond level at a concentration of 0.61 micrograms per liter. Profiles of oxygen and hydrogen stable isotopes were developed for seven sites spaced 300 to 600 feet apart along the southern, downgradient shore of the pond. A transition from heavier to lighter oxygen and hydrogen isotopes was observed at an altitude of about -50 feet. This transition most likely is the boundary between evaporation-affected pond water that is seeping into the aquifer and ground water that has passed beneath the pond. RDX was not detected in the ground-water samples collected south of the pond. Perchlorate was detected only in one sample from a shallow depth in one boring. The results of these analyses indicate that the J-3 Range plume contains low concentrations of RDX and perchlorate (less than 1 microgram per liter) as it passes beneath the northern end of Snake Pond. Results of ground-water-flow modeling indicate that ground water containing these low levels of RDX and perchlorate discharges into the pond south of the island. If the contaminated ground water should travel as far as the southern shore of the pond, it would be overlain near the shore by a zone of pond water seeping into the aquifer that is about 100 feet thick.

Assessment of nonpoint-source contamination of the High Plains Aquifer in south-central Kansas, 1987

USGS Publications Warehouse

Helgesen, John O.; Stullken, Lloyd E.; Rutledge, A.T.

1992-01-01

Ground-water quality was assessed in a 5,000-square-mile area of the High Plains aquifer in south-central Kansas that is susceptible to nonpoint-source contamination from agricultural and petroleum-production activities. Of particular interest were agricultural chemicals, mainly atrazine, and oil-derived hydrocarbons, which might occur in association with brines that formerly were disposed into unlined ponds.Random sampling of ground water was done within a framework of discrete land-use areas (irrigated cropland, petroleum-production land containing former brine-disposal ponds, and undeveloped rangeland) of 3 to 10 square miles. Although true baseline water-quality conditions probably are rare, these baseline conditions are represented most closely by ground water beneath the areas of undeveloped rangeland. The sampling design enabled statistical hypothesis testing of the effects of land use, unsaturated-zone lithology, and type of well sampled. Statistical testing was based on nonparametric procedures.Results indicate that regional ground-water quality has been affected by prevailing land-use activities, as shown mainly by increased concentrations of several inorganic constituents. Ground water beneath irrigated cropland is characterized by significantly (95-percent confidence level) larger concentrations of hardness, alkalinity, calcium, magnesium, potassium, fluoride, and nitrite plus nitrate than is water beneath undeveloped rangeland. Nondegraded pesticides generally were not detected in the aquifer, probably because of degradation and sorption. Atrazine is present locally in ground water in small concentrations.Ground water beneath petroleum-production land is characterized by significantly (95-percent confidence level) larger concentrations of hardness, alkalinity, dissolved solids, sodium, and chloride than is water beneath undeveloped rangeland. Nonpoint-source ground-water contamination by oil-derived hydrocarbons was not discernible. The occurrences of trace-organic compounds were similar between petroleum-production land and undeveloped rangeland, which indicates a natural origin for these compounds.The unsaturated zone in the study area is lithologically heterogeneous and contains substantial amounts of clay that inhibit the downward movement of water and solutes. Within the aquifer, the rate of regional lateral flow and solute transport is sufficiently slow so that the ground-water quality reflects overlying land use in discrete areas of several square miles. Regional flow, however, is sufficiently rapid so that the type of well sampled is not important in regional characterization of water quality beneath irrigated cropland; the seasonal pumping of irrigation wells does not appear to divert regional flow enough to cause substantial local anomalies of more mineralized ground water.

Diffusion and drive-point sampling to detect ordnance-related compounds in shallow ground water beneath Snake Pond, Cape Cod, Massachusetts, 2001-02

USGS Publications Warehouse

LeBlanc, Denis R.

2003-01-01

Diffusion samplers and temporary drive points were used to test for ordnance-related compounds in ground water discharging to Snake Pond near Camp Edwards at the Massachusetts Military Reservation, Cape Cod, MA. The contamination resulted from artillery use and weapons testing at various ranges upgradient of the pond.The diffusion samplers were constructed with a high-grade cellulose membrane that allowed diffusion of explosive compounds, such as RDX (Hexahydro-1,3,5-trinitro-1,3,5-triazine) and HMX (Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine), into deionized water inside the samplers. Laboratory tests confirmed that the cellulose membrane was permeable to RDX and HMX. One transect of 22 diffusion samplers was installed and retrieved in August-September 2001, and 12 transects with a total of 108 samplers were installed and retrieved in September-October 2001. The diffusion samplers were buried about 0.5 feet into the pond-bottom sediments by scuba divers and allowed to equilibrate with the ground water beneath the pond bottom for 13 to 27 days before retrieval. Water samples were collected from temporary well points driven about 2-4 feet into the pond bottom at 21 sites in December 2001 and March 2002 for analysis of explosives and perchlorate to confirm the diffusion-sampling results. The water samples from the diffusion samplers exhibited numerous chromatographic peaks, but evaluation of the photo-diode-array spectra indicated that most of the peaks did not represent the target compounds. The peaks probably are associated with natural organic compounds present in the soft, organically enriched pond-bottom sediments. The presence of four explosive compounds at five widely spaced sites was confirmed by the photo-diode-array analysis, but the compounds are not generally found in contaminated ground water near the ranges. No explosives were detected in water samples obtained from the drive points. Perchlorate was detected at less than 1 microgram per liter in two drive-point samples collected at the same site on two dates about 3 months apart. The source of the perchlorate in the samples could not be related directly to other contamination from Camp Edwards with the available information. The results from the diffusion and drive-point sampling do not indicate an area of ground-water discharge with concentrations of the ordnance-related compounds that are sufficiently elevated to be detected by these sampling methods. The diffusion and drive-point sampling data cannot be interpreted further without additional information concerning the pattern of ground-water flow at Snake Pond and the distributions of RDX, HMX, and perchlorate in ground water in the aquifer near the pond.

Microbial Life beneath a High Arctic Glacier†

PubMed Central

Skidmore, Mark L.; Foght, Julia M.; Sharp, Martin J.

2000-01-01

The debris-rich basal ice layers of a high Arctic glacier were shown to contain metabolically diverse microbes that could be cultured oligotrophically at low temperatures (0.3 to 4°C). These organisms included aerobic chemoheterotrophs and anaerobic nitrate reducers, sulfate reducers, and methanogens. Colonies purified from subglacial samples at 4°C appeared to be predominantly psychrophilic. Aerobic chemoheterotrophs were metabolically active in unfrozen basal sediments when they were cultured at 0.3°C in the dark (to simulate nearly in situ conditions), producing 14CO2 from radiolabeled sodium acetate with minimal organic amendment (≥38 μM C). In contrast, no activity was observed when samples were cultured at subfreezing temperatures (≤−1.8°C) for 66 days. Electron microscopy of thawed basal ice samples revealed various cell morphologies, including dividing cells. This suggests that the subglacial environment beneath a polythermal glacier provides a viable habitat for life and that microbes may be widespread where the basal ice is temperate and water is present at the base of the glacier and where organic carbon from glacially overridden soils is present. Our observations raise the possibility that in situ microbial production of CO2 and CH4 beneath ice masses (e.g., the Northern Hemisphere ice sheets) is an important factor in carbon cycling during glacial periods. Moreover, this terrestrial environment may provide a model for viable habitats for life on Mars, since similar conditions may exist or may have existed in the basal sediments beneath the Martian north polar ice cap. PMID:10919772

Waveform Tomography of the South Atlantic Region

NASA Astrophysics Data System (ADS)

Celli, N. L.; Lebedev, S.; Schaeffer, A. J.; Gaina, C.

2016-12-01

The rapid growth in broadband seismic data, along with developments in waveform tomography techniques, allow us to greatly improve the data sampling in the southern hemisphere and resolve the upper-mantle structure beneath the South Atlantic region at a new level of detail. We have gathered a very large waveform dataset, including all publicly available data from permanent and temporary networks. Our S-velocity tomographic model is constrained by vertical-component waveform fits, computed using the Automated Multimode Inversion of surface, S and multiple S waves. Each seismogram fit provides a set of linear equations describing 1D average velocity perturbations within approximate sensitivity volumes, with respect to a 3D reference model. All the equations are then combined into a large linear system and inverted jointly for a model of shear- and compressional-wave speeds and azimuthal anisotropy within the lithosphere and underlying mantle. The isotropic-average shear speeds are proxies for temperature and composition at depth, while azimuthal anisotropy provides evidence on the past and present deformation in the lithosphere and asthenosphere beneath the region. We resolve the complex boundaries of the mantle roots of South America's and Africa's cratons and the deep low-velocity anomalies beneath volcanic areas in South America. Pronounced lithospheric high seismic velocity anomalies beneath the Argentine Basin suggest that its anomalously deep seafloor, previously attributed to dynamic topography, is mainly due to anomalously cold, thick lithosphere. Major hotspots show low-velocity anomalies extending substantially deeper than those beneath the mid-ocean ridge. The Vema Hotspot shows a major, hot asthenospheric anomaly beneath thick, cold oceanic lithosphere. The mantle lithosphere beneath the Walvis Ridge—a hotspot track—shows normal cooling. The volcanic Cameroon Line, in contrast, is characterized by thin lithosphere beneath the locations of recent volcanism.

Source and transport of human enteric viruses in deep municipal water supply wells

USGS Publications Warehouse

Bradbury, Kenneth R.; Borchardt, Mark A.; Gotkowitz, Madeline; Spencer, Susan K.; Zhu, Jun; Hunt, Randall J.

2013-01-01

Until recently, few water utilities or researchers were aware of possible virus presence in deep aquifers and wells. During 2008 and 2009 we collected a time series of virus samples from six deep municipal water-supply wells. The wells range in depth from approximately 220 to 300 m and draw water from a sandstone aquifer. Three of these wells draw water from beneath a regional aquitard, and three draw water from both above and below the aquitard. We also sampled a local lake and untreated sewage as potential virus sources. Viruses were detected up to 61% of the time in each well sampled, and many groundwater samples were positive for virus infectivity. Lake samples contained viruses over 75% of the time. Virus concentrations and serotypes observed varied markedly with time in all samples. Sewage samples were all extremely high in virus concentration. Virus serotypes detected in sewage and groundwater were temporally correlated, suggesting very rapid virus transport, on the order of weeks, from the source(s) to wells. Adenovirus and enterovirus levels in the wells were associated with precipitation events. The most likely source of the viruses in the wells was leakage of untreated sewage from sanitary sewer pipes.

Pavement Subsidence in the Cumberland Gap Tunnel, USA: A Story of Groundwater Chemistry

NASA Astrophysics Data System (ADS)

Zhu, J.; Currens, J. C.; Webb, S. E.; Rister, B. W.

2014-12-01

Cumberland Gap Tunnel was constructed in 1996 to improve highway travel between southeastern Kentucky and northeastern Tennessee and to restore Cumberland Gap to its historical appearance. About five years after construction, the concrete pavement in the tunnel began to exhibit noticeable signs of subsidence. Ground penetrating radar surveys detected voids in many areas of the limestone roadbed aggregate beneath the pavement. Field investigations conducted by the Kentucky Geological Survey and Kentucky Transportation Center from 2006 to 2008 discovered that groundwater was flowing from the bedrock invert into the aggregate along many parts of the tunnel. Average groundwater discharge from the tunnel was measured at approximately 1700 m3/d. We analyzed 265 groundwater samples collected from aggregate in different parts of the tunnel roadbed during low and high flow conditions. Calculated calcite saturation indices indicated that the groundwater was geochemically aggressive and capable of continuously dissolving calcite in the limestone aggregate although pH values of these water samples were near neutral. We also conducted an in-situ dissolution experiment by placing eight baskets filled with limestone aggregate beneath the roadbed in different locations in the tunnel for 178 days. At the end of the experiment, the limestone aggregate in contact with groundwater exhibited visual signs of dissolution and lost mass, and the highest mass loss recorded was 3.4 percent. Mass loss calculations based on kinetic models of calcite mineral and water samples taken near the baskets matched well with the actual measured mass losses, confirming that dissolution of calcite by the groundwater was the primary cause of the roadbed subsidence problem. Based on these findings, we suggested the limestone aggregate be replaced with noncarbonate (granite) aggregate to mitigate future road subsidence. The suggestion was adopted, and the repair was completed in early 2014.

Constraining the crustal root geometry beneath the Rif Cordillera (North Morocco)

NASA Astrophysics Data System (ADS)

Diaz, Jordi; Gil, Alba; Carbonell, Ramon; Gallart, Josep; Harnafi, Mimoun

2016-04-01

The analyses of wide-angle reflections of controlled source experiments and receiver functions calculated from teleseismic events provide consistent constraints of an over-thickened crust beneath the Rif Cordillera (North Morocco). Regarding active source data, we investigate now offline arrivals of Moho-reflected phases recorded in RIFSIS project to get new estimations of 3D crustal thickness variations beneath North Morocco. Additional constrains on the onshore-offshore transition are derived from onland recording of marine airgun shots from the coeval Gassis-Topomed profiles. A regional crustal thickness map is computed from all these results. In parallel, we use natural seismicity data collected throughout TopoIberia and PICASSO experiments, and from a new RIFSIS deployment, to obtain teleseismic receiver functions and explore the crustal thickness variations with a H-κ grid-search approach. The use of a larger dataset including new stations covering the complex areas beneath the Rif Cordillera allow us to improve the resolution of previous contributions, revealing abrupt crustal changes beneath the region. A gridded surface is built up by interpolating the Moho depths inferred for each seismic station, then compared with the map from controlled source experiments. A remarkably consistent image is observed in both maps, derived from completely independent data and methods. Both approaches document a large modest root, exceeding 50 km depth in the central part of the Rif, in contrast with the rather small topographic elevations. This large crustal thickness, consistent with the available Bouguer anomaly data, favor models proposing that the high velocity slab imaged by seismic tomography beneath the Alboran Sea is still attached to the lithosphere beneath the Rif, hence pulling down the lithosphere and thickening the crust. The thickened area corresponds to a quiet seismic zone located between the western Morocco arcuate seismic zone, the deep seismicity area beneath western Alboran Sea and the superficial seismicity in Alhoceima area. Therefore, the presence of a crustal root seems to play also a major role in the seismicity distribution in northern Morocco.

Aeromagnetic measurements in the Cascade Range and Modoc Plateau of northern California; report on work done from December 1, 1980, to May 31, 1981

USGS Publications Warehouse

Couch, Richard W.; Gemperle, Michael

1982-01-01

Spectral analysis of aeromagnetic data collected over 6orth-central California during the summer of 1980 aided in determining magnetic-source bottom depths beneath the survey area. Five regions of shallow magnetic source bottom depths were detected: 1) Secret Spring Mountain and National Lava Beds Monument area, 2) the Mount Shasta area, 3) the Eddys Mountain area, 4) the Big Valley Mountains area, and 5) an area northeast of Lassen Peak. Except for the Eddys Mountain area, all regions exhibiting shallow depths are suggested to be due to elevated Curie-point isotherms. The elevated Curie-point depth beneath Secret Spring Mountain and the National Lava Beds Monument area was found to be 4-7 km BSL (Below Sea Level) and is an extension of a zone mapped beneath an area immediately to the north in Oregon. A similar depth was detected for the Mount Shasta area and the area northeast of Lassen Peak. A depth of 4-6 km BSL was detected beneath the Big Valley Mountains area. The shallow Curie-point depths beneath Secret Spring Mountain, Mount Shasta, Big Valley Mountains, and the area northeast of Lassen Peak appear to form a segmented Zone of elevated Curie-point isotherm depths which underlies the High Cascade Mountains and Modoc Plateau in north-central California. A small area of shallow depths to magnetic-source bottoms, 4-5 km BSL, beneath the Eddys Mountain area is attributed to a lithologic boundary rather than an elevated Curie-point isotherm. Deeper magnetic source bottom depths were mapped throughout the remainder of the study area, with depths greater than 9 km BSL indicated beneath Lassen Peak and greater than ii km BSL indicated beneath the Western Cascades, Eastern Klamath Mountains, and Great Valley.

Occurrence of nitrate and pesticides in ground water beneath three agricultural land-use settings in the eastern San Joaquin Valley, California, 1993-1995

USGS Publications Warehouse

Burow, Karen R.; Shelton, Jennifer L.; Dubrovsky, Neil M.

1998-01-01

The processes that affect nitrate and pesticide occurrence may be better understood by relating ground-water quality to natural and human factors in the context of distinct, regionally extensive, land- use settings. This study assesses nitrate and pesticide occurrence in ground water beneath three agricultural land-use settings in the eastern San Joaquin Valley, California. Water samples were collected from 60 domestic wells in vineyard, almond, and a crop grouping of corn, alfalfa, and vegetable land-use settings. Each well was sampled once during 1993?1995. This study is one element of the U.S. Geological Survey?s National Water-Quality Assessment Program, which is designed to assess the status of, and trends in, the quality of the nation?s ground- and surface-water resources and to link the status and trends with an understanding of the natural and human factors that affect the quality of water. The concentrations and occurrence of nitrate and pesticides in ground-water samples from domestic wells in the eastern alluvial fan physiographic region were related to differences in chemical applica- tions and to the physical and biogeochemical processes that charac- terize each of the three land-use settings. Ground water beneath the vineyard and almond land-use settings on the coarse-grained, upper and middle parts of the alluvial fans is more vulnerable to nonpoint- source agricultural contamination than is the ground water beneath the corn, alfalfa, and vegetable land-use setting on the lower part of the fans, near the basin physiographic region. Nitrate concentrations ranged from less than 0.05 to 55 milligrams per liter, as nitrogen. Nitrate concentrations were significantly higher in the almond land-use setting than in the vineyard land-use setting, whereas concentrations in the corn, alfalfa, and vegetable land-use setting were intermediate. Nitrate concentrations exceeded the maximum contaminant level in eight samples from the almond land- use setting (40 percent), in seven samples from the corn, alfalfa, and vegetable land-use setting (35 percent), and in three samples from the vineyard land-use setting (15 percent). The physical and chemical characteristics of the vineyard and the almond land-use settings are similar, characterized by coarse-grained sediments and high dissolved- oxygen concentrations, reflecting processes that promote rapid infiltration of water and solutes. The high nitrate concentrations in the almond land-use setting reflect the high amount of nitrogen appli- cations in this setting, whereas the low nitrate concentrations in the vineyard land-use setting reflect relatively low nitrogen applications. In the corn, alfalfa, and vegetable land-use setting, the relatively fine-grained sediments, and low dissolved-oxygen concentrations, reflect processes that result in slow infiltration rates and longer ground-water residence times. The intermediate nitrate concentrations in the corn, alfalfa, and vegetable land-use setting are a result of these physical and chemical characteristics, combined with generally high (but variable) nitrogen applications. Twenty-three different pesticides were detected in 41 of 60 ground- water samples (68 percent). Eighty percent of the ground-water samples from the vineyard land-use setting had at least one pesticide detection, followed by 70 percent in the almond land-use setting, and 55 percent in the corn, alfalfa, and vegetable land-use setting. All concentra- tions were less than state or federal maximum contaminant levels only 5 of the detected pesticides have established maximum contaminant levels) with the exception of 1,2-dibromo-3-chloropropane, which exceeded the maximum contaminant level of 0.2 micrograms per liter in 10 ground-water samples from vineyard land-use wells and in 5 ground- water samples from almond land-use wells. Simazine was detected most often, occurring in 50 percent of the ground-water samples from the vineyard land-use wells and in 30 percent

Sources and sinks of methane beneath polar ice

NASA Astrophysics Data System (ADS)

Priscu, J. C.; Adams, H. E.; Hand, K. P.; Dore, J. E.; Matheus-Carnevali, P.; Michaud, A. B.; Murray, A. E.; Skidmore, M. L.; Vick-Majors, T.

2014-12-01

Several icy moons of the outer solar system carry subsurface oceans containing many times the volume of liquid water on Earth and may provide the greatest volume of habitable space in our solar system. Functional sub-ice polar ecosystems on Earth provide compelling models for the habitability of extraterrestrial sub-ice oceans. A key feature of sub-ice environments is that most of them receive little to no solar energy. Consequently, organisms inhabiting these environments must rely on chemical energy to assimilate either carbon dioxide or organic molecules to support their metabolism. Methane can be utilized by certain bacteria as both a carbon and energy source. Isotopic data show that methane in Earth's polar lakes is derived from both biogenic and thermogenic sources. Thermogenic sources of methane in the thermokarst lakes of the north slope of Alaska yield supersaturated water columns during winter ice cover that support active populations of methanotrophs during the polar night. Methane in the permanently ice-covered lakes of the McMurdo Dry Valleys, Antarctica varies widely in concentration and is produced either by contemporary methanogenesis or is a relic from subglacial flow. Rate measurements revealed that microbial methane oxidation occurs beneath the ice in both the arctic and Antarctic lakes. The first samples collected from an Antarctic subglacial environment beneath 800 m of ice (Subglacial Lake Whillans) revealed an active microbial ecosystem that has been isolated from the atmosphere for many thousands of years. The sediments of Lake Whillans contained high levels of methane with an isotopic signature that indicates it was produced via methanogenesis. The source of this methane appears to be from the decomposition of organic carbon deposited when this region of Antarctica was covered by the sea. Collectively, data from these sub-ice environments show that methane transformations play a key role in microbial community metabolism. The discovery of functional microbial ecosystems in Earth's sub-ice aquatic environments together with what we know about the geochemistry of extraterrestrial ice-covered water worlds provide a compelling case that sub-ice oceans, such as those on Europa and Enceladus, may support microbial life.

Petrological constraints on melt generation beneath the Asal Rift (Djibouti) using quaternary basalts

NASA Astrophysics Data System (ADS)

Pinzuti, Paul; Humler, Eric; Manighetti, Isabelle; Gaudemer, Yves

2013-08-01

The temporal evolution of the mantle melting processes in the Asal Rift is evaluated from the chemical composition of 56 new lava flows sampled along 10 km of the rift axis and 9 km off-axis (i.e., erupted within the last 620 kyr). Petrological and primary geochemical results show that most of the samples of the inner floor of the Asal Rift are affected by plagioclase accumulation. Trace element ratios and major element compositions corrected for mineral accumulation and crystallization show a symmetric pattern relative to the rift axis and preserved a clear signal of mantle melting depth variations. While FeO, Fe8.0, Zr/Y, and (Dy/Yb)N decrease from the rift shoulders to the rift axis, SiO2, Na/Ti, Lu/Hf increase and Na2O and Na8.0 are constant across the rift. These variations are qualitatively consistent with shallow melting beneath the rift axis and deeper melting for off-axis lava flows. Na8.0 and Fe8.0 contents show that beneath the rift axis, melting paths are shallow, from 81 ± 4 to 43 ± 5 km. These melting paths are consistent with adiabatic melting in normal-temperature fertile asthenosphere, beneath an extensively thinned mantle lithosphere. On the contrary, melting on the rift shoulders (from 107 ± 7 to 67 ± 8 km) occurred beneath thicker lithosphere, requiring a mantle solidus temperature 100 ± 40°C hotter. In this geodynamic environment, the calculated rate of lithospheric thinning appears to be 4.0 ± 2.0 cm yr-1, a value close to the mean spreading rate (2.9 ± 0.2 cm yr-1) over the last 620 kyr.

Beneath the floor: re-analysis of neurodevelopmental outcomes in untreated Hurler syndrome.

PubMed

Shapiro, Elsa G; Whitley, Chester B; Eisengart, Julie B

2018-05-11

Hurler syndrome (MPS IH), the severe, neurodegenerative form of type one mucopolysaccharidosis, is associated with rapid neurocognitive decline during toddlerhood and multi-system dysfunction. It is now standardly treated with hematopoietic cell transplantation (HCT), which halts accumulating disease pathology and prevents early death. While norm-based data on developmental functioning in untreated children have previously demonstrated neurocognitive decline, advances in methodology for understanding the cognitive functioning of children with neurodegenerative diseases have highlighted that the previous choice of scores to report results was not ideal. Specifically, the lowest possible norm-based score is 50, which obscures the complete range of cognitive functioning at more advanced stages of neurodeterioration. To a set of cognitive data collected on a sample of untreated children, we applied a modern method of score analysis, calculating a developmental quotient based on age equivalent scores, to reveal the full range of cognitive functioning beneath this cutoff of 50, uncovering new information about the rapidity of decline and the profound impairment in these children. Among 39 observations for 32 patients with untreated Hurler syndrome, the full array of cognitive functioning below 50 includes many children in the severely to profoundly impaired range. The loss of skills per time unit was 14 points between age 1 and 2. There was a very large range of developmental quotients corresponding to the norm-based cutoff of 50. This report enables clarification of functioning at levels that extend beneath the floor of 50 in previous work. At the dawn of newborn screening and amidst a proliferation of new therapies for MPS I, these data can provide crucial benchmark information for developing treatments, particularly for areas of the world where transplant may not be available.

Hydrogeochemistry of groundwaters in and below the base of thick permafrost at Lupin, Nunavut, Canada

NASA Astrophysics Data System (ADS)

Stotler, Randy L.; Frape, Shaun K.; Ruskeeniemi, Timo; Ahonen, Lasse; Onstott, Tullis C.; Hobbs, Monique Y.

2009-06-01

SummaryShield fluids are commonly understood to evolve through water-rock interaction. However, fluids may also concentrate during ice formation. Very little is currently known about groundwater conditions beneath thick permafrost in crystalline environments. This paper evaluates three possible Shield fluid evolution pathways at a crystalline Shield location currently under 500+ meters of permafrost, including surfical cryogenic concentration of seawater, in situ cryogenic concentration and water-rock interaction. A primary goal of this study was to further scientific understanding of permafrost and its role in influencing deep flow system evolution, fluid movement and chemical evolution of waters in crystalline rocks. Precipitation, surface, permafrost and subpermafrost water samples were collected, as well as dissolved and free gas samples, fracture fillings and matrix fluid samples to characterize the site. Investigations of groundwater conditions beneath thick permafrost provides valuable information which can be applied to safety assessment of deep, underground nuclear waste repositories, effects of long-term mining in permafrost areas and understanding analogues to potential life-bearing zones on Mars. The study was conducted in the Lupin gold mine in Nunavut, Canada, located within the zone of continuous permafrost. Through-taliks beneath large lakes in the area provided potential hydraulic connections through the permafrost. Na-Cl and Na-Cl-SO 4 type permafrost waters were contaminated by mining activities, affecting the chloride and nitrate concentrations. High nitrate concentrations (423-2630 mg L -1) were attributed to remnants of blasting. High sulfate concentrations in the permafrost (578-5000 mg L -1) were attributed to naturally occurring and mining enhanced sulfide oxidation. Mine dewatering created an artificial hydraulic gradient, resulting in methane hydrate dissociation at depth. Less contaminated basal waters had medium sulfate concentrations and were Ca-Na dominated, similar to deeper subpermafrost waters. Subpermafrost waters had a wide range of salinities (2.6-40 g L -1). It was unclear from this investigation what impact talik waters would have on deep groundwaters in undisturbed environments. In situ cryogenic concentration due to ice and methane hydrate formation may have concentrated the remaining fluids, however there was no evidence that infiltration of cryogenically concentrated seawater occurred since the last glacial maximum. Matrix waters were dilute and unable to affect groundwater salinity. Fracture infillings were scarce, but calcite fluid inclusion microthermometry indicated a large range in salinities, potentially an additional source of salinity to the system.

Intrawave sand suspension in the shoaling and surf zone of a field-scale laboratory beach

NASA Astrophysics Data System (ADS)

Brinkkemper, J. A.; de Bakker, A. T. M.; Ruessink, B. G.

2017-01-01

Short-wave sand transport in morphodynamic models is often based solely on the near-bed wave-orbital motion, thereby neglecting the effect of ripple-induced and surface-induced turbulence on sand transport processes. Here sand stirring was studied using measurements of the wave-orbital motion, turbulence, ripple characteristics, and sand concentration collected on a field-scale laboratory beach under conditions ranging from irregular nonbreaking waves above vortex ripples to plunging waves and bores above subdued bed forms. Turbulence and sand concentration were analyzed as individual events and in a wave phase-averaged sense. The fraction of turbulence events related to suspension events is relatively high (˜50%), especially beneath plunging waves. Beneath nonbreaking waves with vortex ripples, the sand concentration close to the bed peaks right after the maximum positive wave-orbital motion and shows a marked phase lag in the vertical, although the peak in concentration at higher elevations does not shift to beyond the positive to negative flow reversal. Under plunging waves, concentration peaks beneath the wavefront without any notable phase lags in the vertical. In the inner-surf zone (bores), the sand concentration remains phase coupled to positive wave-orbital motion, but the concentration decreases with distance toward the shoreline. On the whole, our observations demonstrate that the wave-driven suspended load transport is onshore and largest beneath plunging waves, while it is small and can also be offshore beneath shoaling waves. To accurately predict wave-driven sand transport in morphodynamic models, the effect of surface-induced turbulence beneath plunging waves should thus be included.

Composition of the crust beneath the Kenya rift

USGS Publications Warehouse

Mooney, W.D.; Christensen, N.I.

1994-01-01

We infer the composition of the crust beneath and on the flanks of the Kenya rift based on a comparison of the KRISP-90 crustal velocity structure with laboratory measurements of compressional-wave velocities of rock samples from Kenya. The rock samples studied, which are representative of the major lithologies exposed in Kenya, include volcanic tuffs and flows (primarily basalts and phonolites), and felsic to intermediate composition gneisses. This comparison indicates that the upper crust (5-12 km depth) consists primarily of quartzo-feldspathic gneisses and schists similar to rocks exposed on the flanks of the rift, whereas the middle crust (12-22 km depth) consists of more mafic, hornblende-rich metamorphic rocks, probably intruded by mafic rocks beneath the rift axis. The lower crust on the flanks of the rift may consist of mafic granulite facies rocks. Along the rift axis, the lower crust varies in thickness from 9 km in the southern rift to only 2-3 km in the north, and has a seismic velocity substantially higher than the samples investigated in this study. The lower crust of the rift probably consists of a crust/mantle mix of high-grade metamorphic rocks, mafic intrusives, and an igneous mafic residuum accreted to the base of the crust during differentiation of a melt derived from the upper mantle. ?? 1994.

Assessment of nonpoint-source contamination of the High Plains Aquifer in south-central Kansas, 1987

USGS Publications Warehouse

Helgesen, John O.; Stullken, Lloyd E.; Rutledge, A.T.

1994-01-01

Ground-water quality was assessed in a 5,000-square-mile area of the High Plains aquifer in south-central Kansas that is susceptible to nonpoint-source contamination from agricultural and petroleum-production activities. Of particular interest was the presence of agricultural chemicals and petroleum-derived hydrocarbons that might have been associated with brines that formerly were disposed into unlined ponds. Random sampling of ground water was done within a framework of discrete land-use areas (irrigated cropland, petroleum-production land containing former brine-disposal ponds, and undeveloped rangeland) of 3-10 square miles. Although true baseline water-quality conditions probably are rare, in this region they are represented most closely by ground water in areas of undeveloped rangeland. The sampling design enabled statistical hypothesis testing, using nonparametric procedures, of the effects of land use, unsaturated-zone lithology, and type of well sampled. Results indicate that regional ground-water quality has been affected by prevailing land-use activities, as shown by increased concentrations of several inorganic constituents. Ground water beneath irrigated cropland was characterized by significantly larger concentrations of hardness, alkalinity, calcium, magnesium, potassium, fluofide, and nitrite plus nitrate than was water beneath undeveloped rangeland. Few nondegraded pesticides were detected in the aquifer, probably because of degradation and sorption. Atrazine was the most common, but only in small concentrations. round water beneath petroleum-production land was characterized by significantly larger concentrations of hardness, alkalinity, dissolved solids, sodium, and chloride than was water beneath undeveloped rangeland. Nonpoint-source contamination by oil-derived hydrocarbons was not discernible. The occurrences of trace organic compounds were similar between petroleum-production land and undeveloped rangeland, which indicates a natural origin for these compounds. The unsaturated zone in the study area is lithologically heterogeneous and contains substantial amounts of clay that inhibit the downward movement of water and solutes. Within the aquifer, the rate of lateral regional flow and solute transport is slow enough so that the ground-water quality reflects overlying land use in discrete areas of several square miles, but it is still sufficiently rapid so that the type of well sampled is not important in regional characterizations of water quality beneath irrigated cropland; the seasonal pumping of irrigation wells does not appear to divert regional flow enough to cause substantial local anomalies of more mineralized ground water.

Determination of trace levels of herbicides and their degradation products in surface and ground waters by gas chromatography/ion-trap mass spectrometry

USGS Publications Warehouse

Pereira, W.E.; Rostad, C.E.; Leiker, T.J.

1990-01-01

A rapid, specific and highly sensitive method is described for the determination of several commonly used herbicides and their degradation products in surface and ground waters by using gas chromatography/ion-trap mass spectrometry. The compounds included atrazine, and its degradation products desethylatrazine and desisopropylatrazine; Simazine; Cyanazine; Metolachlor; and alachlor and its degradation products, 2-chloro-2', 6'-diethylacetanilide, 2-hydroxy-2', 6'-diethylacetanilide and 2,6-diethylaniline. The method was applied to surface-water samples collected from 16 different stations along the lower Mississippi River and its major tributaries, and ground-water samples beneath a cornfield in central Nebraska. Average recovery of a surrogate herbicide, terbuthylazine, was greater than 99%. Recoveries of the compounds of interest from river water spiked at environmental levels are also presented. Full-scan mass spectra of these compounds were obtained on 1 ng or less of analyte. Data were collected in the full-scan acquisition mode. Quantitation was based on a single characteristic ion for each compound. The detection limit was 60 pg with a signal-to-noise ratio of greater than 10:1.

Seismic properties of the upper mantle beneath Lanzarote (Canary Islands): Model predictions based on texture measurements by EBSD

NASA Astrophysics Data System (ADS)

Vonlanthen, Pierre; Kunze, Karsten; Burlini, Luigi; Grobety, Bernard

2006-12-01

We present a petrophysical analysis of upper mantle xenoliths, collected in the Quaternary alkali basalt fields (Series III and IV) from the island of Lanzarote. The samples consist of eight harzburgite and four dunite nodules, 5 to 15 cm in size, and exhibit a typical protogranular to porphyroclastic texture. An anomalous foliation resulting from strong recovery processes is observed in half of the specimens. The lattice preferred orientations (LPO) of olivine, orthopyroxene and clinopyroxene were measured using electron backscatter diffraction (EBSD). In most samples, olivine exhibits LPOs intermediate between the typical single crystal texture and the [100] fiber texture. Occasionally, the [010] fiber texture was also observed. Simultaneous occurrence of both types of fiber textures suggests the existence of more than one deformation regime, probably dominated by a simple shear component under low strain rate and moderate to high temperature. Orthopyroxene and clinopyroxene display a weaker but significant texture. The LPO data were used to calculate the seismic properties of the xenoliths at PT conditions obtained from geothermobarometry, and were compared to field geophysical data reported from the literature. The velocity of P-waves (7.9 km/s) obtained for a direction corresponding to the existing seismic transect is in good agreement with the most recent geophysical interpretation. Our results are consistent with a roughly W-E oriented fastest P-wave propagation direction in the uppermost mantle beneath the Canary Islands, and with the lithosphere structure proposed by previous authors involving a crust-mantle boundary at around 18 km in depth, overlaid by intermediate material between 11 and 18 km.

P and S wave attenuation tomography of the Japan subduction zone

NASA Astrophysics Data System (ADS)

Wang, Zewei; Zhao, Dapeng; Liu, Xin; Chen, Chuanxu; Li, Xibing

2017-04-01

We determine the first high-resolution P and S wave attenuation (Q) tomography beneath the entire Japan Islands using a large number of high-quality t∗ data collected from P and S wave velocity spectra of 4222 local shallow and intermediate-depth earthquakes. The suboceanic earthquakes used in this study are relocated precisely using sP depth phases. Significant landward dipping high-Q zones are revealed clearly, which reflect the subducting Pacific slab beneath Hokkaido and Tohoku, and the subducting Philippine Sea (PHS) slab beneath SW Japan. Prominent low-Q zones are visible in the crust and mantle wedge beneath the active arc volcanoes in Hokkaido, Tohoku, and Kyushu, which reflect source zones of arc magmatism caused by fluids from the slab dehydration and corner flow in the mantle wedge. Our results also show that nonvolcanic low-frequency earthquakes (LFEs) in SW Japan mainly occur in the transition zone between a narrow low-Q belt and its adjacent high-Q zones right above the flat segment of the PHS slab. This feature suggests that the nonvolcanic LFEs are caused by not only fluid-affected slab interface but also specific conditions such as high pore pressure which is influenced by the overriding plate.

Freeze shoe sampler for the collection of hyporheic zone sediments and porewater.

PubMed

Bianchin, M; Smith, L; Beckie, R

2015-01-01

The Starr and Ingleton (1992) drive point piston sampler (DPPS) design was modified by fitting it with a Murphy and Herkelrath (1996) type sample-freezing drive shoe (SFDS), which uses liquid carbon dioxide as a cryogen. Liquid carbon dioxide was used to freeze sediments in the lower 0.1 m of the core and the drive-point piston sealed the core at the top preserving the reductive-oxidation (redox) sensitive sediments from the atmosphere and maintaining natural stratigraphy. The use of nitrogen gas to provide positive pressure on the gas system blocked the ingress of water which froze on contact with the cryogen thus blocking the gas lines with ice. With this adaptation to the gas system cores could be collected at greater depths beneath the static water level. This tool was used to collect intact saturated sediment cores from the hyporheic zone of the tidally influenced Fraser River in Vancouver, British Columbia, Canada where steep geochemical and microbial gradients develop within the interface between discharging anaerobic groundwater and recharging aerobic river water. In total, 25 cores driven through a 1.5 m sampling interval were collected from the river bed with a mean core recovery of 75%. The ability to deploy this method from a fishing vessel makes the tool more cost effective than traditional marine-based drilling operations which often use barges, tug boats, and drilling rigs. © 2014, National Ground Water Association.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kautsky, Mark; Nguyen, Jason; Darr, Paul S.

The Long-Term Surveillance and Maintenance Plan (LTSMP) for Amchitka details how the U.S. Department of Energy (DOE) intends to fulfill its mission to maintain protection of human health and the environment at and around the sites on Amchitka Island. The LTSMP calls for monitoring to be performed every 5 years, at least in the initial phase of the project. The purpose of the monitoring is to develop a baseline of activity concentrations for selected radionuclides in biota, water, and soil, both on Amchitka and at the reference location on Adak Island, approximately 322 km (200 miles) northeast of Amchitka. Datamore » compiled by the Consortium for Risk Evaluation with Stakeholder Participation (CRESP, 2006) are being included as part of the baseline data set. The specific biological, water, and sediment samples collected during the 2011 sampling event were developed through close coordination with the primary stakeholders, including the Alaska Department of Environmental Conservation, the Aleutian Pribilof Island Association, and the U.S. Fish and Wildlife Service (USFWS). Amchitka is managed by the USFWS as part of the Alaska Maritime National Wildlife Refuge. Two plans were developed to address specific needs of the biological- and the terrestrial-monitoring programs. Results from these monitoring programs will help determine whether the environment is being impacted by radionuclide migration and uptake, and if subsistence and commercial-catch seafood is safe for human consumption. The RESRAD-BIOTA code is being used to evaluate ecological health relative to the radionuclide levels determined from this sampling event. The samples were sent to three laboratories for analysis. With the exception of the seawater samples, most of the samples were sent to the Center for Accelerator Mass Spectrometry at the Lawrence Livermore National Laboratory. A smaller subset of rock-weed samples, Star reindeer lichen samples, and soil samples collected from beneath the lichen were sent to UAF for cesium-137 analysis. Marine sediment samples were also collected and sent to UAF for testing. The seawater samples were sent to the University of Miami Tritium Laboratory for enriched tritium analysis. Results from the seawater samples for tritium were received in September 2011. Results from the 2011 sampling are expected to be available on the LM web site in 2012. (authors)« less

High-resolution seismic reflection imaging of growth folding and shallow faults beneath the Southern Puget Lowland, Washington State

USGS Publications Warehouse

Clement, C.R.; Pratt, T.L.; Holmes, M.L.; Sherrod, B.L.

2010-01-01

Marine seismic reflection data from southern Puget Sound, Washington, were collected to investigate the nature of shallow structures associated with the Tacoma fault zone and the Olympia structure. Growth folding and probable Holocene surface deformation were imaged within the Tacoma fault zone beneath Case and Carr Inlets. Shallow faults near potential field anomalies associated with the Olympia structure were imaged beneath Budd and Eld Inlets. Beneath Case Inlet, the Tacoma fault zone includes an ???350-m wide section of south-dipping strata forming the upper part of a fold (kink band) coincident with the southern edge of an uplifted shoreline terrace. An ???2 m change in the depth of the water bottom, onlapping postglacial sediments, and increasing stratal dips with increasing depth are consistent with late Pleistocene to Holocene postglacial growth folding above a blind fault. Geologic data across a topographic lineament on nearby land indicate recent uplift of late Holocene age. Profiles acquired in Carr Inlet 10 km to the east of Case Inlet showed late Pleistocene or Holocene faulting at one location with ???3 to 4 m of vertical displacement, south side up. North of this fault the data show several other disruptions and reflector terminations that could mark faults within the broad Tacoma fault zone. Seismic reflection profiles across part of the Olympia structure beneath southern Puget Sound show two apparent faults about 160 m apart having 1 to 2 m of displacement of subhorizontal bedding. Directly beneath one of these faults, a dipping reflector that may mark the base of a glacial channel shows the opposite sense of throw, suggesting strike-slip motion. Deeper seismic reflection profiles show disrupted strata beneath these faults but little apparent vertical offset, consistent with strike-slip faulting. These faults and folds indicate that the Tacoma fault and Olympia structure include active structures with probable postglacial motion.

High-resolution seismic reflection imaging of growth folding and shallow faults beneath the Southern Puget Lowland, Washington State

USGS Publications Warehouse

Odum, Jackson K.; Stephenson, William J.; Pratt, Thomas L.; Blakely, Richard J.

2016-01-01

Marine seismic reflection data from southern Puget Sound, Washington, were collected to investigate the nature of shallow structures associated with the Tacoma fault zone and the Olympia structure. Growth folding and probable Holocene surface deformation were imaged within the Tacoma fault zone beneath Case and Carr Inlets. Shallow faults near potential field anomalies associated with the Olympia structure were imaged beneath Budd and Eld Inlets. Beneath Case Inlet, the Tacoma fault zone includes an ∼350-m wide section of south-dipping strata forming the upper part of a fold (kink band) coincident with the southern edge of an uplifted shoreline terrace. An ∼2 m change in the depth of the water bottom, onlapping postglacial sediments, and increasing stratal dips with increasing depth are consistent with late Pleistocene to Holocene postglacial growth folding above a blind fault. Geologic data across a topographic lineament on nearby land indicate recent uplift of late Holocene age. Profiles acquired in Carr Inlet 10 km to the east of Case Inlet showed late Pleistocene or Holocene faulting at one location with ∼3 to 4 m of vertical displacement, south side up. North of this fault the data show several other disruptions and reflector terminations that could mark faults within the broad Tacoma fault zone. Seismic reflection profiles across part of the Olympia structure beneath southern Puget Sound show two apparent faults about 160 m apart having 1 to 2 m of displacement of subhorizontal bedding. Directly beneath one of these faults, a dipping reflector that may mark the base of a glacial channel shows the opposite sense of throw, suggesting strike-slip motion. Deeper seismic reflection profiles show disrupted strata beneath these faults but little apparent vertical offset, consistent with strike-slip faulting. These faults and folds indicate that the Tacoma fault and Olympia structure include active structures with probable postglacial motion.

Effect of home construction on soil carbon storage-A chronosequence case study.

PubMed

Majidzadeh, Hamed; Lockaby, B Graeme; Governo, Robin

2017-07-01

Urbanization results in the rapid expansion of impervious surfaces, therefore a better understanding of biogeochemical consequences of soil sealing is crucial. Previous research documents a significant reduction in soil carbon and nitrogen content, however, it is unclear if this decrease is a result of top soil removal or long-term soil sealing. In this study, soil biogeochemical properties were quantified beneath homes built on a crawl space at two depths (0-10 cm, and 10-20 cm). All homes, 11-114 years in age, were sampled in the Piedmont region of Alabama and Georgia, USA. This age range enabled the use of a chronosequence approach to estimate carbon loss or gain under the sampled homes. The difference in soil carbon content beneath homes and adjoining urban lawns showed a quadratic relation with age. Maximum C loss occurred at approximately fifty years. The same pattern was observed for MBC: C ratio suggesting that the soil carbon content was decreasing beneath the homes for first fifty years, then increased afterward. The average soil C and N content in the top 10 cm were respectively 61.86% (±4.42%), and 65.77% (±5.65%) lower underneath the homes in comparison to urban lawns. Microbial biomass carbon (MBC), and nitrogen (MBN) were significantly lower below the homes compared to the urban lawns, while bulk density and phosphorus content were higher beneath the homes. Copyright © 2017 Elsevier Ltd. All rights reserved.

Topography of upper mantle seismic discontinuities beneath the North Atlantic: The Azores, Canary and Cape Verde plumes

NASA Astrophysics Data System (ADS)

Saki, Morvarid; Thomas, Christine; Nippress, Stuart E. J.; Lessing, Stephan

2015-01-01

We are mapping the topography of upper mantle seismic discontinuities beneath the North Atlantic and surrounding regions by using precursor arrivals to PP and SS seismic waves that reflect off the seismic discontinuities. Numerous source-receiver combinations have been used in order to collect a large dataset of reflection points beneath our investigation area. We analysed over 1700 seismograms from MW > 5.8 events using array seismic methods to enhance the signal to noise ratio. The measured time lag between PP (SS) arrivals and their corresponding precursors on robust stacks are used to measure the depth of the transition zone boundaries. The reflectors' depths show a correlation between the location of known hotspots and a significantly depressed 410 km discontinuity indicating a temperature increase of 50-300 K compared to the surrounding mantle. For the 660 km discontinuity three distinct behaviours are visible: (i) normal depths beneath Greenland and at a distance of a few hundred kilometres away from known hotspots, (ii) shallower 660 km discontinuity compared with the global average value near hotspots closer to the Mid-Atlantic Ridge, and (iii) very few observations of a 660 km discontinuity at the hotspot locations. We interpret our observations as a large upwelling beneath the southern parts of our study region, possibly due to the South Atlantic convection cell. The thermal anomaly may be ponding beneath the endothermic 660 km phase transformation and likely does not extend through the top of the transition zone as a whole, except for those branches which appear as the thinner upwellings of Azores, Canaries and Cape Verde hotspots at the surface.

Lowermost mantle anisotropy and deformation along the boundary of the African LLSVP

NASA Astrophysics Data System (ADS)

Lynner, Colton; Long, Maureen D.

2014-05-01

Shear wave splitting of SK(K)S phases is often used to examine upper mantle anisotropy. In specific cases, however, splitting of these phases may reflect anisotropy in the lowermost mantle. Here we present SKS and SKKS splitting measurements for 233 event-station pairs at 34 seismic stations that sample D″ beneath Africa. Of these, 36 pairs show significantly different splitting between the two phases, which likely reflects a contribution from lowermost mantle anisotropy. The vast majority of discrepant pairs sample the boundary of the African large low shear velocity province (LLSVP), which dominates the lower mantle structure beneath this region. In general, we observe little or no splitting of phases that have passed through the LLSVP itself and significant splitting for phases that have sampled the boundary of the LLSVP. We infer that the D″ region just outside the LLSVP boundary is strongly deformed, while its interior remains undeformed (or weakly deformed).

Predicting reaerosolization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Daniel, William Brent; Omberg, Kristin M

2010-11-29

Outdoor studies of the environmental persistence of bacteria have led to many interesting results. It turns out that the initial deposition of bacteria is not the end of the story. We examined both the ongoing daily deposition and aerosolization of bacteria for two weeks following an initial deposition event. Differences between samples collected in a clearing and those collected beneath a forest canopy were also examined. There were two important results: first, bacteria were still moving about in significant quantities after two weeks, though the local environment where they were most prevalent appeared to shift over time; second, we weremore » able to develop a simple mathematical model that could fairly accurately estimate the average daily airborne concentration of bacteria over the duration of the experiment using readily available environmental information. The implication is that deposition patterns are very likely to shift over an extended period of time following a release, possibly quite significantly, but there is hope that we may be able to estimate these changes fairly accurately.« less

The preservation of ancient solar wind particles buried beneath lunar basalt flows as determined through heat transfer modeling

NASA Astrophysics Data System (ADS)

Rumpf, M. E.; Fagents, S. A.; Crawford, I. A.; Joy, K. H.

2009-12-01

The ever-changing environment on the Earth’s surface has erased any record of the early solar system. However, the antiquity of lunar surface combined with its negligible atmosphere and magnetosphere would have created conditions favorable for the preservation of ancient solar wind particles, galactic cosmic ray particles, and material that originated on other bodies in the inner solar system. Ancient particles emplaced in the regolith and subsequently buried beneath mare lava flows may have been preserved from subsequent bombardment provided the volatiles survived heat introduced by the lava flow. Discovery and extraction of such particles will aid in the advancement of several current solar system exploration goals, including studying the record of solar wind gases and investigating ancient atmospheric compositions on Earth and other inner planets. It has been shown that different volatile species will be released from the regolith when heated to specific temperature ranges between 573 and 973 K. We have developed a finite-volume numerical model that simulates heat transfer between a mare lava flow and the underlying regolith, to predict the preservation potential of ancient particles within layered deposits in the lunar maria. Results show that a 1 m thick basalt flow initially at 1500 K will heat an underlying regolith deposit to release implanted volatile species buried to a depth of 3.7 to 28 cm beneath the regolith surface; pristine samples would be preserved beneath these depths. At the estimated regolith formation rate of ~5 mm/Ma during the peak of mare volcanism (~3.6-3.8 Ga), an exposure time exceeding 7.4 to 56 Ma would be required prior to burial by the ensuing lava flow. Heating depths and required regolith formation times scale in direct proportion to the thickness of the overlying flow. Emplacement of multiple flow units over several hundred Ma would create intercalated stacks of lavas and regolith units, which could be radiometrically dated to provide a time series of the variability in intensity and composition of the solar wind. Suitable locations include Oceanus Procellarum, which contains numerous lava units ranging in age from 3.5-1.2 Ga. Extraction of implanted volatiles of a range of ages would require drilling through perhaps tens of meters of flow units and intervening paleoregoliths, which in turn indicates the need for tens to hundreds of km surface mobility and the provision for adequate sample collection and return. Detection of suitable paleoregolith deposits would be aided by tools such as ground penetrating radar. Although it may be argued that long-range robotic rover and sample return missions could tackle this objective, we propose that the complexity of the task is most readily addressed by a sortie-class human expedition to key sites in the lunar maria.

Deep long-period earthquakes beneath Washington and Oregon volcanoes

NASA Astrophysics Data System (ADS)

Nichols, M. L.; Malone, S. D.; Moran, S. C.; Thelen, W. A.; Vidale, J. E.

2011-03-01

Deep long-period (DLP) earthquakes are an enigmatic type of seismicity occurring near or beneath volcanoes. They are commonly associated with the presence of magma, and found in some cases to correlate with eruptive activity. To more thoroughly understand and characterize DLP occurrence near volcanoes in Washington and Oregon, we systematically searched the Pacific Northwest Seismic Network (PNSN) triggered earthquake catalog for DLPs occurring between 1980 (when PNSN began collecting digital data) and October 2009. Through our analysis we identified 60 DLPs beneath six Cascade volcanic centers. No DLPs were associated with volcanic activity, including the 1980-1986 and 2004-2008 eruptions at Mount St. Helens. More than half of the events occurred near Mount Baker, where the background flux of magmatic gases is greatest among Washington and Oregon volcanoes. The six volcanoes with DLPs (counts in parentheses) are Mount Baker (31), Glacier Peak (9), Mount Rainier (9), Mount St. Helens (9), Three Sisters (1), and Crater Lake (1). No DLPs were identified beneath Mount Adams, Mount Hood, Mount Jefferson, or Newberry Volcano, although (except at Hood) that may be due in part to poorer network coverage. In cases where the DLPs do not occur directly beneath the volcanic edifice, the locations coincide with large structural faults that extend into the deep crust. Our observations suggest the occurrence of DLPs in these areas could represent fluid and/or magma transport along pre-existing tectonic structures in the middle crust.

Deep long-period earthquakes beneath Washington and Oregon volcanoes

USGS Publications Warehouse

Nichols, M.L.; Malone, S.D.; Moran, S.C.; Thelen, W.A.; Vidale, J.E.

2011-01-01

Deep long-period (DLP) earthquakes are an enigmatic type of seismicity occurring near or beneath volcanoes. They are commonly associated with the presence of magma, and found in some cases to correlate with eruptive activity. To more thoroughly understand and characterize DLP occurrence near volcanoes in Washington and Oregon, we systematically searched the Pacific Northwest Seismic Network (PNSN) triggered earthquake catalog for DLPs occurring between 1980 (when PNSN began collecting digital data) and October 2009. Through our analysis we identified 60 DLPs beneath six Cascade volcanic centers. No DLPs were associated with volcanic activity, including the 1980-1986 and 2004-2008 eruptions at Mount St. Helens. More than half of the events occurred near Mount Baker, where the background flux of magmatic gases is greatest among Washington and Oregon volcanoes. The six volcanoes with DLPs (counts in parentheses) are Mount Baker (31), Glacier Peak (9), Mount Rainier (9), Mount St. Helens (9), Three Sisters (1), and Crater Lake (1). No DLPs were identified beneath Mount Adams, Mount Hood, Mount Jefferson, or Newberry Volcano, although (except at Hood) that may be due in part to poorer network coverage. In cases where the DLPs do not occur directly beneath the volcanic edifice, the locations coincide with large structural faults that extend into the deep crust. Our observations suggest the occurrence of DLPs in these areas could represent fluid and/or magma transport along pre-existing tectonic structures in the middle crust. ?? 2010 Elsevier B.V.

Nitrogen Species in Soil, Sediment, and Ground Water at a Former Sewage-Treatment Wastewater Lagoon: Naval Air Station Whidbey Island, Island County, Washington

USGS Publications Warehouse

Cox, S.E.; Dinicola, R.S.; Huffman, R.L.

2007-01-01

The potential for contamination of ground water from remnant sewage sludge in re-graded sediments of a deconstructed sewage-treatment lagoon was evaluated. Ground-water levels were measured in temporary drive-point wells, and ground-water samples were collected and analyzed for nutrients and other water-quality characteristics. Composite soil and sediment samples were collected and analyzed for organic carbon and nitrogen species. Multiple lines of evidence, including lack of appreciable organic matter in sediments of the former lagoon, agronomic analysis of nitrogen, the sequestration of nitrogen in the developing soils at the former lagoon, and likely occurrence of peat deposits within the aquifer material, suggest that the potential for substantial additions of nitrogen to ground water beneath the former sewage lagoon resulting from remnant sewage sludge not removed from the former lagoon are small. Concentrations of nitrogen species measured in ground-water samples were small and did not exceed the established U.S. Environmental Protection Agency's maximum contaminant levels for nitrate (10 milligrams per liter). Concentrations of nitrate in ground-water samples were less than the laboratory reporting limit of 0.06 milligram per liter. Seventy to 90 percent of the total nitrogen present in ground water was in the ammonia form with a maximum concentration of 7.67 milligrams per liter. Concentrations of total nitrogen in ground water beneath the site, which is the sum of all forms of nitrogen including nitrate, nitrite, ammonia, and organic nitrogen, ranged from 1.15 to 8.44 milligrams per liter. Thus, even if all forms of nitrogen measured in ground water were converted to nitrate, the combined mass would be less than the maximum contaminant level. Oxidation-reduction conditions in ground water beneath the former sewage lagoon were reducing. Given the abundant supply of ambient organic carbon in the subsurface and in ground water at the former lagoon, any nitrate that may leach from residual sludge and be transported to ground water with recharge is expected to be quickly denitrified or transformed to nitrite and ammonia under the strongly reducing geochemical conditions that are present. Concentrations of organic carbon, the primary constituent of sewage sludge, in sediments of the former sewage lagoon were less than 1 percent, indicating a near absence of organic matter. The amount of total nitrogen present in the sediments at the former sewage lagoon was only about 25 percent of the amount typically present in developed agricultural soils. The lack of substantial carbon and nitrogen in sediments of the former sewage lagoon indicates that surficial sediments of the former lagoon are essentially devoid of residual sewage sludge. The largest concentration of total nitrogen measured in soil samples from the former sewage lagoon (330 milligrams per kilogram) was used to calculate an estimate of the amount of nitrogen that might be leached from residual sewage sludge by recharge. During the first two years following deconstruction of the former sewage lagoon, the concentration of total nitrogen in recharge leachate might exceed 10 milligrams per liter but the recharge leachate would not likely result in substantial increases in the nitrate concentration in ground water to concentrations greater than the drinking-water maximum contaminant level of 10 milligrams per liter.

Evaluation of pore-water samplers at a drainage ditch, Installation Restoration Site 4, Naval Air Station Corpus Christi, Corpus Christi, Texas, 2005–06

USGS Publications Warehouse

Vroblesky, Don A.; Casey, Clifton C.

2007-01-01

The U.S. Geological Survey, in cooperation with the Naval Facilities Engineering Command Southeast, used innovative sampling methods to investigate ground-water contamination by chlorobenzenes beneath a drainage ditch on the southwestern side of Installation Restoration Site 4, Naval Air Station Corpus Christi, Corpus Christi, Texas, during 2005-06. The drainage ditch, which is a potential receptor for ground-water contaminants from Installation Restoration Site 4, intermittently discharges water to Corpus Christi Bay. This report evaluates a new type of pore-water sampler developed for this investigation to examine the subsurface contamination beneath the drainage ditch. The new type of pore-water sampler appears to be an effective approach for long-term monitoring of ground water in the sand and organic-rich mud beneath the drainage ditch.

F-Area Acid/Caustic Basin groundwater monitoring report: Third quarter 1994

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1994-12-01

During third quarter 1994, samples from the FAC monitoring wells at the F-Area Acid/Caustic Basin were collected and analyzed for herbicides/pesticides, indicator parameters, metals, nitrate, radionuclide indicators, volatile organic compounds, and other constituents. Piezometer FAC 5P and monitoring well FAC 6 were dry and could not be sampled. New monitoring wells FAC 9C, 10C, 11C, and 12C were sampled for the first time during third quarter. Analytical results that exceeded final Primary Drinking Water Standards (PDWS), other Savannah River Site (SRS) Flag 2 criteria, or the SRS turbidity standard of 50 NTU during the quarter were as follows: gross alphamore » exceeded the final PDWS and aluminum, iron, manganese, and total alpha-emitting radium exceeded the SRS Flag 2 criteria in one or more of the FAC wells. Turbidity exceeded the SRS standard in wells FAC 3 and 10C. Groundwater flow direction and rate in the water table beneath the F-Area Acid/Caustic Basin were similar to past quarters.« less

Continuous resistivity profiling data from the Corsica River Estuary, Maryland

USGS Publications Warehouse

Cross, V.A.; Bratton, J.F.; Worley, C.R.; Crusius, John; Kroeger, K.D.

2011-01-01

Submarine groundwater discharge (SGD) into Maryland's Corsica River Estuary was investigated as part of a larger study to determine its importance in nutrient delivery to the Chesapeake Bay. The Corsica River Estuary represents a coastal lowland setting typical of much of the eastern bay. An interdisciplinary U.S. Geological Survey (USGS) science team conducted field operations in the lower estuary in April and May 2007. Resource managers are concerned about nutrients that are entering the estuary via SGD that may be contributing to eutrophication, harmful algal blooms, and fish kills. Techniques employed in the study included continuous resistivity profiling (CRP), piezometer sampling of submarine groundwater, and collection of a time series of radon tracer activity in surface water. A CRP system measures electrical resistivity of saturated subestuarine sediments to distinguish those bearing fresh water (high resistivity) from those with saline or brackish pore water (low resistivity). This report describes the collection and processing of CRP data and summarizes the results. Based on a grid of 67.6 kilometers of CRP data, low-salinity (high-resistivity) groundwater extended approximately 50-400 meters offshore from estuary shorelines at depths of 5 to >12 meters below the sediment surface, likely beneath a confining unit. A band of low-resistivity sediment detected along the axis of the estuary indicated the presence of a filled paleochannel containing brackish groundwater. The meandering paleochannel likely incised through the confining unit during periods of lower sea level, allowing the low-salinity groundwater plumes originating from land to mix with brackish subestuarine groundwater along the channel margins and to discharge. A better understanding of the spatial variability and geological controls of submarine groundwater flow beneath the Corsica River Estuary could lead to improved models and mitigation strategies for nutrient over-enrichment in the estuary and in other similar settings.

Investigation of the potential source area, contamination pathway, and probable release history of chlorinated-solvent-contaminated groundwater at the Capital City Plume Site, Montgomery, Alabama, 2008-2010

USGS Publications Warehouse

Landmeyer, James E.; Miller, Scott; Campbell, Bruce G.; Vroblesky, Don A.; Gill, Amy C.; Clark, Athena P.

2011-01-01

Detection of the organic solvent perchloroethylene (PCE) in a shallow public-supply well in 1991 and exposure of workers in 1993 to solvent vapors during excavation activities to depths near the water table provided evidence that the shallow aquifer beneath the capital city of Montgomery, Alabama, was contaminated. Investigations conducted from 1993 to 1999 by State and Federal agencies confirmed the detection of PCE in the shallow aquifer, as well as the detection of the organic solvent trichloroethylene (TCE) and various inorganic compounds, but the source of the groundwater contamination was not determined. In May 2000 the U.S. Environmental Protection Agency proposed that the site, called the Capital City Plume (CCP) Site, be a candidate for the National Priorities List. Between 2000 and 2007, numerous site-investigation activities also did not determine the source of the groundwater contamination. In 2008, additional assessments were conducted at the CCP Site to investigate the potential source area, contamination pathway, and the probable release history of the chlorinated-solvent-contaminated groundwater. The assessments included the collection of (1) pore water in 2008 from the hyporheic zone of a creek using passive-diffusion bag samplers; (2) tissue samples in 2008 and 2009 from trees growing in areas of downtown Montgomery characterized by groundwater contamination and from trees growing in riparian zones along the Alabama River and Cypress Creek; and (3) groundwater samples in 2009 and 2010. The data collected were used to investigate the potential source area of contaminants detected in groundwater, the pathway of groundwater contamination, and constraints on the probable contaminant-release history. The data collected between 2008 and 2010 indicate that the PCE and TCE contamination of the shallow aquifer beneath the CCP Site most likely resulted from the past use and disposal of industrial wastewater from printing operations containing chlorinated solvents into the sanitary sewer and (or) stormwater systems of Montgomery. Moreover, chlorinated-solvent use and disposal occurred at least between the 1940s and 1970s at several locations occupied by printing operations. The data also indicate that PCE and TCE contamination continues to occur in the shallow subsurface near potential release areas and that PCE and TCE have been transported to the intermediate part of the shallow aquifer.

Crustal structure of the Colorado Plateau, Arizona: Application of new long-offset seismic data analysis techniques

USGS Publications Warehouse

Parsons, T.; McCarthy, J.; Kohler, W.M.; Ammon, C.J.; Benz, H.M.; Hole, J.A.; Criley, E.E.

1996-01-01

The Colorado Plateau is a large crustal block in the southwestern United States that has been raised intact nearly 2 km above sea level since Cretaceous marine sediments were deposited on its surface. Controversy exists concerning the thickness of the plateau crust and the source of its buoyancy. Interpretations of seismic data collected on the plateau vary as to whether the crust is closer to 40 or 50 km thick. A thick crust could support the observed topography of the Colorado Plateau isostatically, while a thinner crust would indicate the presence of an underlying low-density mantle. This paper reports results on long-offset seismic data collected during the 1989 segment of the U.S. Geological Survey Pacific to Arizona Crustal Experiment that extended from the Transition Zone into the Colorado Plateau in northwest Arizona. We apply two new methods to analyze long-offset data that employ finite difference travel time calculations: (1) a first-arrival time inverter to find upper crustal velocity structure and (2) a forward-modeling technique that allows the direct use of the inverted upper crustal solution in modeling secondary reflected arrivals. We find that the crustal thickness increases from 30 km beneath the metamorphic core complexes in the southern Basin and Range province to about 42 km beneath the northern Transition Zone and southern Colorado Plateau margin. We observe some crustal thinning (to ???37 km thick) and slightly higher lower crustal velocities farther inboard; beneath the Kaibab uplift on the north rim of the Grand Canyon the crust thickens to a maximum of 48 km. We observe a nonuniform crustal thickness beneath the Colorado Plateau that varies by ???15% and corresponds approximately to variations in topography with the thickest crust underlying the highest elevations. Crustal compositions (as inferred from seismic velocities) appear to be the same beneath the Colorado Plateau as those in the Basin and Range province to the southwest, implying that the plateau crust represents an unextended version of the Basin and Range. Some of the variability in crustal structure appears to correspond to preserved lithospheric discontinuities that date back to the Proterozoic Era.

Hydrogeology, chemical and microbial activity measurement through deep permafrost

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stotler, R.L.; Frape, S.K.; Freifeld, B.M.

2010-04-01

Little is known about hydrogeochemical conditions beneath thick permafrost, particularly in fractured crystalline rock, due to difficulty in accessing this environment. The purpose of this investigation was to develop methods to obtain physical, chemical, and microbial information about the subpermafrost environment from a surface-drilled borehole. Using a U-tube, gas and water samples were collected, along with temperature, pressure, and hydraulic conductivity measurements, 420 m below ground surface, within a 535 m long, angled borehole at High Lake, Nunavut, Canada, in an area with 460-m-thick permafrost. Piezometric head was well above the base of the permafrost, near land surface. Initial watermore » samples were contaminated with drill fluid, with later samples <40% drill fluid. The salinity of the non-drill fluid component was <20,000 mg/L, had a Ca/Na ratio above 1, with {delta}{sup 18}O values {approx}5{per_thousand} lower than the local surface water. The fluid isotopic composition was affected by the permafrost-formation process. Nonbacteriogenic CH{sub 4} was present and the sample location was within methane hydrate stability field. Sampling lines froze before uncontaminated samples from the subpermafrost environment could be obtained, yet the available time to obtain water samples was extended compared to previous studies. Temperature measurements collected from a distributed temperature sensor indicated that this issue can be overcome easily in the future. The lack of methanogenic CH{sub 4} is consistent with the high sulfate concentrations observed in cores. The combined surface-drilled borehole/U-tube approach can provide a large amount of physical, chemical, and microbial data from the subpermafrost environment with few, controllable, sources of contamination.« less

Hydrogeology, Chemical and Microbial Activity Measurement Through Deep Permafrost

USGS Publications Warehouse

Stotler, R.L.; Frape, S.K.; Freifeld, B.M.; Holden, B.; Onstott, T.C.; Ruskeeniemi, T.; Chan, E.

2011-01-01

Little is known about hydrogeochemical conditions beneath thick permafrost, particularly in fractured crystalline rock, due to difficulty in accessing this environment. The purpose of this investigation was to develop methods to obtain physical, chemical, and microbial information about the subpermafrost environment from a surface-drilled borehole. Using a U-tube, gas and water samples were collected, along with temperature, pressure, and hydraulic conductivity measurements, 420 m below ground surface, within a 535 m long, angled borehole at High Lake, Nunavut, Canada, in an area with 460-m-thick permafrost. Piezometric head was well above the base of the permafrost, near land surface. Initial water samples were contaminated with drill fluid, with later samples <40% drill fluid. The salinity of the non-drill fluid component was <20,000 mg/L, had a Ca/Na ratio above 1, with ??18O values ???5??? lower than the local surface water. The fluid isotopic composition was affected by the permafrost-formation process. Nonbacteriogenic CH4 was present and the sample location was within methane hydrate stability field. Sampling lines froze before uncontaminated samples from the subpermafrost environment could be obtained, yet the available time to obtain water samples was extended compared to previous studies. Temperature measurements collected from a distributed temperature sensor indicated that this issue can be overcome easily in the future. The lack of methanogenic CH4 is consistent with the high sulfate concentrations observed in cores. The combined surface-drilled borehole/U-tube approach can provide a large amount of physical, chemical, and microbial data from the subpermafrost environment with few, controllable, sources of contamination. ?? 2010 The Author(s). Journal compilation ?? 2010 National Ground Water Association.

Tracing recharge to aquifers beneath an Asian megacity with Cl/Br and stable isotopes: the example of Dhaka, Bangladesh

NASA Astrophysics Data System (ADS)

Hoque, M. A.; McArthur, J. M.; Sikdar, P. K.; Ball, J. D.; Molla, T. N.

2014-06-01

Dhaka, the capital of Bangladesh, is home to a population of 15 million people, whose water supply is 85% drawn from groundwater in aquifers that underlie the city. Values of Cl/Br >500 are common in groundwater beneath western Dhaka in areas <3 km from the river, and in rivers and sewers around and within the city. The study shows that groundwater beneath western Dhaka is strongly influenced by infiltration of effluent from leaking sewers and unsewered sanitation, and by river-bank infiltration from the Turag-Buriganga river system which bounds the western limit of the city. River-bank infiltration from other rivers around Dhaka is minor. Values of Cl/Br and Cl concentrations reveal that 23 % of wells sampled in Dhaka are influenced by saline connate water in amounts up to 1%. This residual natural salinity compromises the use of electrical conductivity of groundwater as a method for defining pathways of recharge by contaminated surface waters. Concentrations of As, B, Ba, Cd, Cu, F, Ni, NO3, Pb, Sb, Se and U in groundwater samples are less than WHO health-based guideline values for drinking water.

Electrostatic discharge test apparatus

NASA Technical Reports Server (NTRS)

Smith, William Conrad (Inventor)

1988-01-01

Electrostatic discharge properties of materials are quantitatively measured and ranked. Samples are rotated on a turntable beneath selectable, co-available electrostatic chargers, one being a corona charging element and the other a sample-engaging triboelectric charging element. Samples then pass under a voltage meter to measure the amount of residual charge on the samples. After charging is discontinued, measurements are continued to record the charge decay history over time.

Petrological Constraints on Melt Generation Beneath the Asal Rift (Djibouti)

NASA Astrophysics Data System (ADS)

Pinzuti, P.; Humler, E.; Manighetti, I.; Gaudemer, Y.; Bézos, A.

2010-12-01

The temporal evolution of the mantle melting processes in the Asal Rift is evaluated from the chemical composition of 95 lava flows sampled along 10 km of the rift axis and 8 km off-axis (that is for the last 650 ky). The major element composition and the trace element ratios of aphyric basalts across the Asal Rift show a symmetric pattern relative to the rift axis and preserved a clear signal of mantle melting depth variations. FeO, Fe8.0, Sm/YbN and Zr/Y increase, whereas SiO2 and Lu/HfN decrease from the rift axis to the rift shoulders. These variations are qualitatively consistent with a shallower melting beneath the rift axis than off-axis and the data show that the melting regime is inconsistent with a passive upwelling model. In order to quantify the depth range and extent of melting, we invert Na8.0 and Fe8.0 contents of basalts based on a pure active upwelling model. Beneath the rift axis, melting paths are shallow, from 60 to 30 km. These melting paths are consistent with adiabatic melting in normal-temperature asthenosphere, beneath an extensively thinned mantle lithosphere. In contrast, melting on the rift shoulders occurred beneath a thick mantle lithosphere and required mantle solidus temperature 180°C hotter than normal (melting paths from 110 to 75 km). The calculated rate of lithospheric thinning is high (6.0 cm yr-1) and could explain the survival of a metastable garnet within the mantle at depth shallower than 90 km beneath the modern Asal Rift.

Concentrations of hormones, pharmaceuticals and other micropollutants in groundwater affected by septic systems in New England and New York.

PubMed

Phillips, P J; Schubert, C; Argue, D; Fisher, I; Furlong, E T; Foreman, W; Gray, J; Chalmers, A

2015-04-15

Septic-system discharges can be an important source of micropollutants (including pharmaceuticals and endocrine active compounds) to adjacent groundwater and surface water systems. Groundwater samples were collected from well networks tapping glacial till in New England (NE) and sandy surficial aquifer New York (NY) during one sampling round in 2011. The NE network assesses the effect of a single large septic system that receives discharge from an extended health care facility for the elderly. The NY network assesses the effect of many small septic systems used seasonally on a densely populated portion of Fire Island. The data collected from these two networks indicate that hydrogeologic and demographic factors affect micropollutant concentrations in these systems. The highest micropollutant concentrations from the NE network were present in samples collected from below the leach beds and in a well downgradient of the leach beds. Total concentrations for personal care/domestic use compounds, pharmaceutical compounds and plasticizer compounds generally ranged from 1 to over 20 μg/L in the NE network samples. High tris(2-butoxyethyl phosphate) plasticizer concentrations in wells beneath and downgradient of the leach beds (>20 μg/L) may reflect the presence of this compound in cleaning agents at the extended health-care facility. The highest micropollutant concentrations for the NY network were present in the shoreline wells and reflect groundwater that is most affected by septic system discharges. One of the shoreline wells had personal care/domestic use, pharmaceutical, and plasticizer concentrations ranging from 0.4 to 5.7 μg/L. Estradiol equivalency quotient concentrations were also highest in a shoreline well sample (3.1 ng/L). Most micropollutant concentrations increase with increasing specific conductance and total nitrogen concentrations for shoreline well samples. These findings suggest that septic systems serving institutional settings and densely populated areas in coastal settings may be locally important sources of micropollutants to adjacent aquifer and marine systems. Published by Elsevier B.V.

Geochemistry of soils from the San Rafael Valley, Santa Cruz County, Arizona

USGS Publications Warehouse

Folger, Helen W.; Gray, Floyd

2013-01-01

This study was conducted to determine whether surficial geochemical methods can be used to identify subsurface mineraldeposits covered by alluvium derived from surrounding areas. The geochemical investigation focused on an anomalous geo-physical magnetic high located in the San Rafael Valley in Santa Cruz County, Arizona. The magnetic high, inferred to be asso-ciated with a buried granite intrusion, occurs beneath Quaternary alluvial and terrace deposits. Soil samples were collected at a depth of 10 to 30 centimeters below land surface along transects that traverse the inferred granite. The samples were analyzed by inductively coupled plasma-mass spectrometry and by the partial-leach Mobile Metal Ion™ method. Principal component and factor analyses showed a strong correlation between the soils and source rocks hosting base-metal replacement deposits in the Harshaw and Patagonia Mining Districts. Factor analysis also indicated areas of high metal concentrations associated with the Meadow Valley Flat. Although no definitive geochemical signature was identified for the inferred granite, concentrations otungsten and iron in the surrounding area were slightly elevated.

Petrologic Constraints on Magma Plumbing Systems Beneath Hawaiian Volcanoes

NASA Astrophysics Data System (ADS)

Li, Y.; Peterman, K. J.; Scott, J. L.; Barton, M.

2016-12-01

We have calculated the pressures of partial crystalliztion of basaltic magmas from Hawaii using a petrological method. A total of 1576 major oxide analyses of glasses from four volcanoes (Kilauea and the Puna Ridge, Loihi, Mauna Loa, and Mauna Kea, on the Big Island) were compiled and used as input data. Glasses represent quenched liquid compositions and are ideal for calculation of pressures of partial crystallization. The results were filtered to exclude samples that yielded unrealistic high errors associated with the calculated pressure or negative value of pressure, and to exclude samples with non-basaltic compositions. Calculated pressures were converted to depths of partial crystallization. The majority (68.2%) of pressures for the shield-stage subaerial volcanoes Kilauea, Mauna Loa, and Mauna Kea, fall in the range 0-140 MPa, corresponding to depths of 0-5 km. Glasses from the Puna Ridge yield pressures ranging from 18 to 126 MPa and are virtually identical to pressures determined from glasses from Kilauea (0 to 129 MPa). These results are consistent with the presence of magma reservoirs at depths of 0-5 km beneath the large shield volcanoes. The inferred depth of the magma reservoir beneath the summit of Kilauea (average = 1.8 km, maximum = 5 km) agrees extremely well with depths ( 2-6 km) estimated from seismic studies. The results for Kilauea and Mauna Kea indicate that significant partial crystallization also occurs beneath the summit reservoirs at depths up to 11 km. These results are consistent with seismic evidence for the presence of a magma reservoir at 8-11 km beneath Kilauea at the base of the volcanic pile. The results for Loihi indicate crystallization at higher average pressures (100-400 MPa) and depths (3-14 km) than the large shield volcanoes, suggesting that the plumbing system is not yet fully developed, and that the Hawaiian volcanic plumbing systems evolve over time.

Relationship between Famatinian Arc Magmatism and Recent Mafic Volcanism in Northwest Argentina: Implications for Lithospheric Composition and Evolution Beneath the Puna Plateau

NASA Astrophysics Data System (ADS)

Drew, S.; Schoenbohm, L.; Ducea, M.

2008-12-01

The tectonic and magmatic evolution of the Puna Plateau (NW Argentina) has generated much debate over the past two decades. This study focuses on the young (< 7 Ma), mafic magmatism that led to the creation of monogenetic and simple polygenetic volcanoes throughout the plateau. These volcanics provide a means to evaluate the recent petro-tectonic development of the plateau and, in combination with Ordovician intrusive rocks, determine the isotopic composition and long term evolution of the sub-continental lithospheric mantle (SCLM) beneath the Andean back-arc domain. Here we present new whole rock major and trace element data and isotopic values for volcanic samples collected from the Antofagasta and Pasto Ventura basins in the southern Puna Plateau. Major element chemistry shows most of our samples are basalt, trachybasalt, basaltic andesite and basaltic trachyandesites, some with < 50.0 wt% SiO2 and > 8.0 wt% MgO, which is indicative of a strong mantle component. The more primitive lavas likely have a sub-crustal origin and experienced minimal interaction with overlying crust during transport to the surface. Two of our samples with low wt% MgO, a silicic andesite and a dacite, indicate an extensive crustal component and possibly a lower crust origin for evolved magmas. All samples have light trace element enrichment compared to NMORB and elevated abundances of LIL and LRE elements compared to HFS and HRE elements, indicating the magmas originated from a metasomatized source region. The samples also have variable (low and high) Nb, Ta and Ti negative anomalies, which are interpreted to be a signature of the source region. Our samples do not have a lithospheric delamination (~OIB) trace element signature as proposed by previous workers in support of a delamination model. Additionally, the samples have isotopic values (e.g. 87Sr/86Sr >0.7055 and ɛNd <0) that are not comparable to depleted asthenosphere. It is impossible for asthenospheric magma to obtain these isotopic values through crustal assimilation or AFC processes while maintaining a basalt major element composition and high Ni and Cr concentrations. Therefore, we propose the mafic magmas are sourced from a SCLM that, in accord with the LIL and LRE element concentrations, has been metasomatized during dehydration and possibly melting of a subducting oceanic plate. The young volcanics have isotopic values nearly identical to those of Early Ordovician Famatinian gabbros and norites. We suggest the most primitive Puna volcanic and Famatinian samples originated from the same SCLM source region. This implies at least a thin portion of the SCLM has remained intact beneath NW Argentina for the last ~485 million years. Resultantly, the SCLM was likely thinned to its present thickness sometime between the Early Ordovician and the Late Miocene. Thinning may have occurred by long term mantle wedge processes. Steady shortening and thickening of the continental crust and gradual removal of the SCLM by convection is envisioned here. The occurrence of discrete, intermittent delamination events is not favored because removal and then regeneration of the SCLM would not have allowed for preservation of the Famatinian isotopic signature.

Sewage in ground water in the Florida Keys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shinn, E.A.

1995-12-31

More than 24,000 septic tanks, 5,000 cesspools, and greater than 600 shallow disposal wells introduce sewage effluents into porous and permeable limestone underlying the Florida Keys. To porous and permeable limestone underlying the Florida Keys. To assess the fate of sewage nutrients, 21 2- to 20-m-deep wells were core drilled and completed as water-monitoring wells. The wells were sampled quarterly and analyzed for 17 parameters. including nutrients and bacteria. Nutrients (mainly NH4, - which is 30 to 40 times higher than in surface sea water) were detected in ground water beneath the Keys and offshore coral reefs. Highest levels weremore » beneath reefs 5 to 8 km offshore. Ground waters were generally hypersaline and fecal bacteria (fecal coliform and streptococci) were detected in ground water beneath living coral reefs. Higher sea level on the Florida Bay side of the Keys is proposed as the mechanism for forcing ground water toward offshore coral reefs. Tidal pumping, which is more pronounced near the Keys, causes leakage of ground water where the sediment is thin. Areas lacking sediment cover consist of bare limestone bedrock or permeable coral reefs. These are the areas where coral diseases and algal growth have increased in recent years. Pollutants entering the ground water beneath the Florida Keys are likely to be transported seaward beneath impermeable Holocene sediments and may be upwelling through coral reefs and other hardbottom communities.« less

Radiological survey results at Building 22, Washington Navy Yard, Washington, D.C. (WNS001)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rodriguez, R.E.; Foley, R.D.; Uziel, M.S.

A radiological survey was conducted in a portion of Building 22 at the Washington Navy Yard, Washington, D.C., on December 13, 1995. The survey was performed because former employees thought the area surveyed had some previous association with radioactive material. Employees remembered seeing radiation signs in the area and indicated that personnel occupying this area wore dosimeters. Two rooms in the survey area were surrounded by 1-ft-thick poured concrete walls and similar 6-in.-thick ceilings, and situated on top of a 1-ft-thick concrete slab, a configuration commonly used for radiation shielding in industrial radiography facilities. The radiological survey showed no gamma,more » beta-gamma, or alpha measurements above typical background levels. Low background radiation levels within the building indicated that even if low-level contamination were present beneath the tile, or larger amounts of contamination beneath the concrete slab, it poses no radiological hazard to building inhabitants under the present conditions. Further investigation may be required before drilling or demolition of the concrete slab. No photon radiation fields from sealed gamma sources or x-ray sources were detectable at the time of the survey. Gamma spectrometry analysis revealed no gamma emitters above typical background concentrations in one sediment and one water sample collected from a pit in the open bay area.« less

A mini drivepoint sampler for measuring pore water solute concentrations in the hyporheic zone of sand-bottom streams

USGS Publications Warehouse

Duff, J.H.; Murphy, F.; Fuller, C.C.; Triska, F.J.

1998-01-01

A new method for collecting pore-water samples in sand and gravel streambeds is presented. We developed a mini drivepoint solution sampling (MINIPOINT) technique to collect pore-water samples at 2.5-cm vertical resolution. The sampler consisted of six small-diameter stainless steel drivepoints arranged in a 10-cm-diameter circular array. In a simple procedure, the sampler was installed in the streambed to preset drivepoint depths of 2.5, 5.0, 7.5, 10.0, 12.5, and 15.0 cm. Sampler performance was evaluated in the Shingobee River, Minnesota, and Pinal Creek, Arizona, by measuring the vertical gradient of chloride concentration in pore water beneath the streambed that was established by the uninterrupted injection to the stream for 3 d. Pore-water samples were withdrawn from all drivepoints simultaneously. In the first evaluation, the vertical chloride gradient was unchanged at withdrawal rates between 0.3 and 4.0 ml min-1 but was disturbed at higher rates. In the second evaluation, up to 70 ml of pore water was withdrawn from each drivepoint at a withdrawal rate of 2.5 ml min-1 without disturbing the vertical chloride gradient. Background concentrations of other solutes were also determined with MINIPOINT sampling. Steep vertical gradients were present for biologically reactive solutes such as DO, NH4/+, NO3/-, and dissolved organic C in the top 20 cm of the streambed. These detailed solute profiles in the hyporheic zone could not have been determined without a method for close interval vertical sampling that does not disturb natural hydrologic mixing between stream water and groundwater.

Topography of Upper Mantle Seismic Discontinuities Beneath the North Atlantic: The Azores, Canary and Cape Verde Plumes

NASA Astrophysics Data System (ADS)

Thomas, C.; Saki, M.; Nippress, S. E. J.; Lessing, S.

2014-12-01

We are mapping the topography of upper mantle seismic discontinuities beneath the North Atlantic and surrounding regions by using precursor arrivals to PP and SS seismic waves that reflect off the seismic discontinuities. Numerous source-receiver combinations have been used in order to collect a large dataset of reflection points beneath our investigation area. We analysed over 1700 seismograms from MW>5.8 events using array seismic methods to enhance the signal to noise ratio. The measured time lag between PP (SS) arrivals and their corresponding precursors on robust stacks are used to measure the depth of the transition zone boundaries. The reflectors' depths show a correlation between the location of known hotspots and a significantly depressed 410 km discontinuity indicating a temperature increase of 50-300 K compared to the surrounding mantle. For the 660 km discontinuity three distinct behaviours are visible: i) normal depths beneath Greenland and at a distance of a few hundred kilometres away from known hotspots, ii) shallower 660 km discontinuity compared with the global average value near hotspots closer to the Mid-Atlantic Ridge and iii) very few observations of a 660 km discontinuity at the hotspot locations. We interpret our observations as a large upwelling beneath the southern parts of our study region, possibly due to the South Atlantic convection cell. The thermal anomaly may be blocked by endothermic phase transformation and likely does not extend through the top of the transition zone except for those branches which appear as the Azores, Canaries and Cape Verde hotspots at the surface.

Topography of upper mantle seismic discontinuities beneath the North Atlantic: the Azores, Canary and Cape Verde plumes

NASA Astrophysics Data System (ADS)

Saki, Morvarid; Thomas, Christine; Nippress, Stuart E. J.; Lessing, Stephan

2015-04-01

We are mapping the topography of upper mantle seismic discontinuities beneath the North Atlantic and surrounding regions by using precursor arrivals to PP and SS seismic waves that reflect off the seismic discontinuities. Many source-receiver combinations have been used in order to collect a large dataset of reflection points beneath our investigating area. We analyzed over 1700 seismograms from MW>5.8 events using array seismic methods to enhance the signal to noise ratio. The measured time lag between PP (SS) arrivals and their corresponding precursors on robust stacks are used to measure the depth of the transition zone boundaries. The reflectors' depths show a correlation between the location of hotspots and a significantly depressed 410 km discontinuity indicating a temperature increase of 200-300 K compared to the surrounding mantle. For the 660 km discontinuity three distinct behaviours are visible: i) normal depths beneath Greenland and at a distance of a few hundred kilometres away from the hotspots and ii) shallower 660 km discontinuity compared with the global average value near hotspots closer to the Mid-Atlantic Ridge and iii) very few observations of a 660 km discontinuity at the hotspot locations. We interpret our observations as a large upwelling beneath the southern parts of our study region, possibly due to the South Atlantic convection cell. The thermal anomaly may be blocked by endothermic phase transformation and likely does not extend through the top of the transition zone as whole except for those branches which appear as the Azores, Canaries and Cape Verde hotspots at the surface.

Campaign gravity results From kilauea volcano, hawaii, 2009-2011

NASA Astrophysics Data System (ADS)

Wilkinson, S. K.; Poland, M. P.; Battaglia, M.

2011-12-01

The gravity and leveling networks at Kilauea's summit caldera consist of approximately 60 benchmarks that are measured with a gravimeter as well as leveled for elevation data. Gravity data were collected in December 2009, June 2010 and March 2011. Elevation data were collected in 2009 and 2010. For the gravity survey completed in March 2011, we use InSAR and GPS data to assess elevation changes at the time of the gravity survey. During December 2009-March 2011, Kilauea's summit was characterized by minor deflation, following trends established in mid-2007. In mid-2010, however, the summit began to inflate, with a rate that increased significantly in October 2010. This inflation was associated with a decrease in the effusion rate from the volcano's east rift zone eruptive vents, suggesting that Kilauea's magma plumbing system was backing up. On March 5, 2011, a 2-km-long fissure eruption began about 3 km west of Pu`u `O`o, causing rapid summit deflation as magma drained from beneath the summit to feed the new eruptive vents. The fissure eruption ended on March 9, at which time the summit began to reinflate. Preliminary analysis of gravity data collected before and after the fissure eruption indicates a complex pattern of mass flow beneath the summit caldera. Net summit deformation was negligible between December 2009 and June 2010, but there is a residual gravity high centered near Halema'uma'u Crater. For the December 2009 to March 2011 time period, the caldera shows net subsidence. A positive residual gravity anomaly is located southeast of Halema'uma'u Crater while a negative residual gravity anomaly exists north of Halema'uma'u Crater. These patterns are somewhat unexpected, given the sudden draining of magma from beneath the summit during the March 5-9 fissure eruption. We conclude that the campaign gravity data were not collected at the optimal times to "catch" this event. Nevertheless, the data can still be used to assess different aspects of Kilauea's magma system.

Distribution and Characteristics of Seafloor Seepage Features in the Active Margin Offshore of SW Taiwan

NASA Astrophysics Data System (ADS)

Chen, T. T.; Hsu, H. H.; Liu, C. S.; Su, C. C.; Paull, C. K.; Chen, Y. H.; Caress, D. W.; Gwiazda, R.; Lundsten, E. M.

2017-12-01

In the active margin offshore of southwest (SW) Taiwan, west-vergent imbricated thrusts, folds and dipping strata are the main structural features. This is also the area where gas hydrates are widely distributed beneath the seafloor. Fluids from deep strata may migrate upwards along porous dipping layers or faults and then vent out to form seafloor seepage features in many of the gas hydrate prospects. A joint survey was conducted in May 2017 using MBARI mapping AUV and miniROV to investigate the seafloor seepage features. Numerous comet-shaped depressions (CSD) are mapped along flanks of several anticlinal ridges, and four carbonate mounds around CSD are observed from the ultra-high-resolution (1-m lateral resolution) bathymetry data collected by AUV. Samples of the carbonate mounds were collected by the mini-ROV, and their mineral compositions contain dolomite and ankerite. The AUV collected chirp sonar profiles and previously collected surface ship multichannel seismic reflection profiles across these seafloor features show that potential fluid migration pathways connect free gas trapped below the base of gas hydrate stability zone and the seafloor in the vicinity of these features. Our study suggests that the CSD could be an indicator of seafloor seepage and may be distribution widely in the active margin setting.

A microbial ecosystem beneath the West Antarctic ice sheet.

PubMed

Christner, Brent C; Priscu, John C; Achberger, Amanda M; Barbante, Carlo; Carter, Sasha P; Christianson, Knut; Michaud, Alexander B; Mikucki, Jill A; Mitchell, Andrew C; Skidmore, Mark L; Vick-Majors, Trista J

2014-08-21

Liquid water has been known to occur beneath the Antarctic ice sheet for more than 40 years, but only recently have these subglacial aqueous environments been recognized as microbial ecosystems that may influence biogeochemical transformations on a global scale. Here we present the first geomicrobiological description of water and surficial sediments obtained from direct sampling of a subglacial Antarctic lake. Subglacial Lake Whillans (SLW) lies beneath approximately 800 m of ice on the lower portion of the Whillans Ice Stream (WIS) in West Antarctica and is part of an extensive and evolving subglacial drainage network. The water column of SLW contained metabolically active microorganisms and was derived primarily from glacial ice melt with solute sources from lithogenic weathering and a minor seawater component. Heterotrophic and autotrophic production data together with small subunit ribosomal RNA gene sequencing and biogeochemical data indicate that SLW is a chemosynthetically driven ecosystem inhabited by a diverse assemblage of bacteria and archaea. Our results confirm that aquatic environments beneath the Antarctic ice sheet support viable microbial ecosystems, corroborating previous reports suggesting that they contain globally relevant pools of carbon and microbes that can mobilize elements from the lithosphere and influence Southern Ocean geochemical and biological systems.

The U-tube: A novel system for acquiring borehole fluid samples from a deep geologic CO2 sequestration experiment

USGS Publications Warehouse

Freifeild, Barry M.; Trautz, Robert C.; Kharaka, Yousif K.; Phelps, Tommy J.; Myer, Larry R.; Hovorka, Susan D.; Collins, Daniel J.

2005-01-01

A novel system has been deployed to obtain geochemical samples of water and gas, at in situ pressure, during a geologic CO2 sequestration experiment conducted in the Frio brine aquifer in Liberty County, Texas. Project goals required high-frequency recovery of representative and uncontaminated aliquots of a rapidly changing two-phase fluid (supercritical CO2 and brine) fluid from 1.5 km depth. The data sets collected, using both the liquid and gas portions of the downhole samples, provide insights into the coupled hydrogeochemical issues affecting CO2sequestration in brine-filled formations. While the basic premise underlying the U-tube sampler is not new, the system is unique because careful consideration was given to the processing of the recovered two-phase fluids. In particular, strain gauges mounted beneath the high-pressure surface sample cylinders measured the ratio of recovered brine to supercritical CO2. A quadrupole mass spectrometer provided real-time gas analysis for perfluorocarbon and noble gas tracers that were injected along with the CO2. The U-tube successfully acquired frequent samples, facilitating accurate delineation of the arrival of the CO2 plume, and on-site analysis revealed rapid changes in geochemical conditions.

The U-tube: A novel system for acquiring borehole fluid samples from a deep geologic CO2 sequestration experiment

USGS Publications Warehouse

Freifeild, Barry M.; Trautz, Robert C.; Kharaka, Yousif K.; Phelps, Tommy J.; Myer, Larry R.; Hovorka, Susan D.; Collins, Daniel J.

2005-01-01

A novel system has been deployed to obtain geochemical samples of water and gas, at in situ pressure, during a geologic CO2 sequestration experiment conducted in the Frio brine aquifer in Liberty County, Texas. Project goals required high-frequency recovery of representative and uncontaminated aliquots of a rapidly changing two-phase fluid (supercritical CO2 and brine) fluid from 1.5 km depth. The data sets collected, using both the liquid and gas portions of the downhole samples, provide insights into the coupled hydrogeochemical issues affecting CO2 sequestration in brine-filled formations. While the basic premise underlying the U-tube sampler is not new, the system is unique because careful consideration was given to the processing of the recovered two-phase fluids. In particular, strain gauges mounted beneath the high-pressure surface sample cylinders measured the ratio of recovered brine to supercritical CO2. A quadrupole mass spectrometer provided real-time gas analysis for perfluorocarbon and noble gas tracers that were injected along with the CO2. The U-tube successfully acquired frequent samples, facilitating accurate delineation of the arrival of the CO2 plume, and on-site analysis revealed rapid changes in geochemical conditions.

The U-tube: A novel system for acquiring borehole fluid samples from a deep geologic CO2 sequestration experiment

NASA Astrophysics Data System (ADS)

Freifeld, Barry M.; Trautz, Robert C.; Kharaka, Yousif K.; Phelps, Tommy J.; Myer, Larry R.; Hovorka, Susan D.; Collins, Daniel J.

2005-10-01

A novel system has been deployed to obtain geochemical samples of water and gas, at in situ pressure, during a geologic CO2 sequestration experiment conducted in the Frio brine aquifer in Liberty County, Texas. Project goals required high-frequency recovery of representative and uncontaminated aliquots of a rapidly changing two-phase fluid (supercritical CO2 and brine) fluid from 1.5 km depth. The data sets collected, using both the liquid and gas portions of the downhole samples, provide insights into the coupled hydrogeochemical issues affecting CO2 sequestration in brine-filled formations. While the basic premise underlying the U-tube sampler is not new, the system is unique because careful consideration was given to the processing of the recovered two-phase fluids. In particular, strain gauges mounted beneath the high-pressure surface sample cylinders measured the ratio of recovered brine to supercritical CO2. A quadrupole mass spectrometer provided real-time gas analysis for perfluorocarbon and noble gas tracers that were injected along with the CO2. The U-tube successfully acquired frequent samples, facilitating accurate delineation of the arrival of the CO2 plume, and on-site analysis revealed rapid changes in geochemical conditions.

Complex seismic anisotropy beneath Germany from shear wave splitting and surface wave models

NASA Astrophysics Data System (ADS)

Campbell, L.; Long, M. D.; Becker, T. W.; Lebedev, S.

2013-12-01

Seismic anisotropy beneath stable continental interiors likely reflects a host of processes, including deformation in the lower crust, frozen anisotropy from past deformation processes in the lithospheric mantle, and present-day mantle flow in the asthenosphere. Because the anisotropic structure beneath continental interiors is generally complicated and often exhibits heterogeneity both laterally and with depth, a complete characterization of anisotropy and its interpretation in terms of deformational processes is challenging. In this study, we aim to expand our understanding of continental anisotropy by characterizing in detail the geometry and strength of azimuthal anisotropy beneath Germany and the surrounding region, using a combination of shear wave splitting and surface wave constraints. We utilize data from long-running broadband stations in and around Germany, collected from a variety of national and temporary European networks. We measure the splitting of SKS, SKKS, and PKS phases, with the aim of obtaining the best possible backazimuthal coverage. Preliminary results indicate that anisotropy beneath Germany is generally complex; we observe shear wave splitting patterns that are complicated and are inconsistent with a single horizontal layer of anisotropy beneath the station. Observed delay times are generally small (<1 sec), and there is a preponderance of null *KS arrivals in the dataset, with null measurements detected over a fairly large range of backazimuths. We also observe dramatic differences in splitting patterns over relatively short horizontal distances. Although we note backazimuthal variations in splitting at several stations, we do not observe a clear 90-degree periodicity that one would expect for the case of multiple anisotropic layers. We are currently carrying out comparisons between our observed splitting patterns and those predicted from tomographic models of azimuthal anisotropy derived from surface wave observations. The ultimate goal of this work is to combine different types of observations (shear wave splitting, surface wave models, and eventually anisotropic receiver function analysis) to place precise constraints on the anisotropic structure beneath Germany, and to interpret this structure in terms of on-going and past deformational processes in the crust and mantle.

Corrective Action Investigation Plan for Corrective Action Unit 428: Area 3 Septic Waste Systems 1 and 5, Tonopah Test Range, Nevada, REVISION 0, march 1999

DOE Office of Scientific and Technical Information (OSTI.GOV)

ITLV.

1999-03-01

The Corrective Action Investigation Plan for Corrective Action Unit 428, Area 3 Septic Waste Systems 1 and 5, has been developed in accordance with the Federal Facility Agreement and Consent Order that was agreed to by the U. S. Department of Energy, Nevada Operations Office; the State of Nevada Division of Environmental Protection; and the U. S. Department of Defense. Corrective Action Unit 428 consists of Corrective Action Sites 03- 05- 002- SW01 and 03- 05- 002- SW05, respectively known as Area 3 Septic Waste System 1 and Septic Waste System 5. This Corrective Action Investigation Plan is used inmore » combination with the Work Plan for Leachfield Corrective Action Units: Nevada Test Site and Tonopah Test Range, Nevada , Rev. 1 (DOE/ NV, 1998c). The Leachfield Work Plan was developed to streamline investigations at leachfield Corrective Action Units by incorporating management, technical, quality assurance, health and safety, public involvement, field sampling, and waste management information common to a set of Corrective Action Units with similar site histories and characteristics into a single document that can be referenced. This Corrective Action Investigation Plan provides investigative details specific to Corrective Action Unit 428. A system of leachfields and associated collection systems was used for wastewater disposal at Area 3 of the Tonopah Test Range until a consolidated sewer system was installed in 1990 to replace the discrete septic waste systems. Operations within various buildings at Area 3 generated sanitary and industrial wastewaters potentially contaminated with contaminants of potential concern and disposed of in septic tanks and leachfields. Corrective Action Unit 428 is composed of two leachfield systems in the northern portion of Area 3. Based on site history collected to support the Data Quality Objectives process, contaminants of potential concern for the site include oil/ diesel range total petroleum hydrocarbons, and Resource Conservation and Recovery Act characteristic volatile organic compounds, semivolatile organic compounds, and metals. A limited number of samples will be analyzed for gamma- emitting radionuclides and isotopic uranium from four of the septic tanks and if radiological field screening levels are exceeded. Additional samples will be analyzed for geotechnical and hydrological properties and a bioassessment may be performed. The technical approach for investigating this Corrective Action Unit consists of the following activities: Perform video surveys of the discharge and outfall lines. Collect samples of material in the septic tanks. Conduct exploratory trenching to locate and inspect subsurface components. Collect subsurface soil samples in areas of the collection system including the septic tanks and outfall end of distribution boxes. Collect subsurface soil samples underlying the leachfield distribution pipes via trenching. Collect surface and near- surface samples near potential locations of the Acid Sewer Outfall if Septic Waste System 5 Leachfield cannot be located. Field screen samples for volatile organic compounds, total petroleum hydrocarbons, and radiological activity. Drill boreholes and collect subsurface soil samples if required. Analyze samples for total volatile organic compounds, total semivolatile organic compounds, total Resource Conservation and Recovery Act metals, and total petroleum hydrocarbons (oil/ diesel range organics). Limited number of samples will be analyzed for gamma- emitting radionuclides and isotopic uranium from particular septic tanks and if radiological field screening levels are exceeded. Collect samples from native soils beneath the distribution system and analyze for geotechnical/ hydrologic parameters. Collect and analyze bioassessment samples at the discretion of the Site Supervisor if total petroleum hydrocarbons exceed field- screening levels.« less

Water and Streambed Sediment Quality, and Ecotoxicology of a Stream along the Blue Ridge Parkway, Adjacent to a Closed Landfill, near Roanoke, Virginia: 1999

USGS Publications Warehouse

Ebner, Donna Belval; Cherry, Donald S.; Currie, Rebecca J.

2004-01-01

A study was done of the effects of a closed landfill on the quality of water and streambed sediment and the benthic macroinvertebrate community of an unnamed stream and its tributary that flow through Blue Ridge Parkway lands in west-central Virginia. The primary water source for the tributary is a 4-inch polyvinyl chloride (PVC) pipe that protrudes from the slope at the base of the embankment bordering the landfill. An unusual expanse of precipitate was observed in the stream near the PVC pipe. Stream discharge was measured and water and streambed sediment samples were collected at a nearby reference site and at three sites downstream of the landfill in April and September 1999. Water samples were analyzed for major ions, nitrate, total and dissolved metals, total dissolved solids, total organic carbon, and volatile and semivolatile organic compounds, including organochlorine pesticides and polychlorinated biphenyls (PCBs). Streambed sediment samples were analyzed for total metals, total organic carbon, percent moisture, and volatile and semivolatile organic compounds, including organochlorine pesticides and PCBs. The benthic macroinvertebrate community within the stream channel also was sampled at the four chemical sampling sites and at one additional site in April and September. Each of the five sites was assessed for physical habitat quality. Water collected periodically at the PVC pipe discharge between November 1998 and November 1999 was used to conduct 48-hour acute and 7-day chronic toxicity tests using selected laboratory test organisms. Two 10-day chronic toxicity tests of streambed sediments collected near the discharge pipe also were conducted. Analyses showed that organic and inorganic constituents in water from beneath the landfill were discharged into the sampled tributary. In April, 79 percent of inorganic constituents detected in water had their highest concentrations at the site closest to the landfill; at the same site, 59 percent of inorganic constituents detected in streambed sediments were at their lowest concentration. The low dissolved-oxygen concentration and relatively low pH in ground water from beneath the landfill probably had a direct effect on the solubility of metals and other constituents, resulting in the high concentration of inorganic constituents in water, low concentration in sediment, and the development of the precipitate. Most constituents in water in April were progressively lower in concentration from the landfill site downstream. The highest concentrations for 59 percent of constituents detected in sediment were at the farthest downstream site, suggesting that the inorganic constituents came out of solution as the stream water was exposed to the atmosphere. In September, 52 percent of inorganic constituents detected in water were at their highest concentrations at the site nearest the landfill. Of inorganic constituents detected in streambed sediments in September, 60 percent were at their highest concentrations near the landfill. A storm that occurred a few days prior to the September sampling probably affected the preceding steady-state conditions and the distribution of constituents in sediment along the stream. Concentrations of many inorganic constituents in water remained elevated at the farthest downstream site in comparison to the reference site in April and September, indicating that concentrations did not return to background concentrations. In April and September, most of the 17 organic compounds detected in water, including volatile organic and semivolatile organic compounds, were collected in samples near the landfill, and most concentrations were below their respective reporting limits. Probably because of their volatility, few organic compounds were detected at sites downstream of that site. A total of 17 discrete organic compounds were detected in sediment samples in either April or September, including trichloroethene and tetrachloroethene along with their degrad

Investigation of the lithosphere of the Texas Gulf Coast using phase-specific Ps receiver functions produced by wavefield iterative deconvolution

NASA Astrophysics Data System (ADS)

Gurrola, H.; Berdine, A.; Pulliam, J.

2017-12-01

Interference between Ps phases and reverberations (PPs, PSs phases and reverberations thereof) make it difficult to use Ps receiver functions (RF) in regions with thick sediments. Crustal reverberations typically interfere with Ps phases from the lithosphere-asthenosphere boundary (LAB). We have developed a method to separate Ps phases from reverberations by deconvolution of all the data recorded at a seismic station by removing phases from a single wavefront at each iteration of the deconvolution (wavefield iterative deconvolution or WID). We applied WID to data collected in the Gulf Coast and Llano Front regions of Texas by the EarthScope Transportable array and by a temporary deployment of 23 broadband seismometers (deployed by Texas Tech and Baylor Universities). The 23 station temporary deployment was 300 km long; crossing from Matagorda Island onto the Llano uplift. 3-D imaging using these data shows that the deepest part of the sedimentary basin may be inboard of the coastline. The Moho beneath the Gulf Coast plain does not appear in many of the images. This could be due to interference from reverberations from shallower layers or it may indicate the lack of a strong velocity contrast at the Moho perhaps due to serpentinization of the uppermost mantle. The Moho appears to be flat, at 40 km) beneath most of the Llano uplift but may thicken to the south and thin beneath the Coastal plain. After application of WID, we were able to identify a negatively polarized Ps phase consistent with LAB depths identified in Sp RF images. The LAB appears to be 80-100 km deep beneath most of the coast but is 100 to 120 km deep beneath the Llano uplift. There are other negatively polarized phases between 160 and 200 km depths beneath the Gulf Coast and the Llano Uplift. These deeper phases may indicate that, in this region, the LAB is transitional in nature and rather than a discrete boundary.

Suburban groundwater quality as influenced by turfgrass and septic sources, Delmarva Peninsula, USA

USGS Publications Warehouse

Kasper, Joshua W.; Denver, Judith M.; York, Joanna K.

2015-01-01

Suburban land use is expanding in many parts of the United States and there is a need to better understand the potential water-quality impacts of this change. This study characterized groundwater quality in a sandy, water-table aquifer influenced by suburban development and compared the results to known patterns in water chemistry associated with natural, background conditions and agricultural effects. Samples for nutrients, major ions, and isotopes of N and O in NO3− were collected in 2011 beneath turfgrass from 29 shallow wells (median depth 3.7 m) and from 18 deeper wells (median depth 16.9 m) in a long-term suburban development. Nitrate (as N) concentrations in groundwater beneath turfgrass were highly variable (0.02–22.3 mg L−1) with a median of 2.7 mg L−1, which is higher than natural water chemistry (>0.4 mg L−1; Na+–Cl−–HCO3− water type), but significantly lower than concentrations beneath a nearby agricultural area (median 16.9 mg L−1; p < .0001). Dissolved Fe concentrations in shallow suburban groundwater, attributed to chelated Fe in turfgrass fertilizers, were significantly higher (p < .005) than concentrations from the agricultural site, although a Ca2+–Mg2+–Cl−–NO3− water type was dominant in both areas. A Na+–Cl−–NO3− water type indicated a septic-system source for nitrate in deep suburban groundwater (0.06–6.0 mg L−1; median 1.5 mg L−1). Isotopic data indicated denitrification; however, geochemical techniques were more helpful in identifying nitrate sources. Results indicate that suburban expansion into agricultural areas may significantly decrease overall nitrate concentrations in groundwater, but excessive turfgrass fertilization could result in localized contamination.

Temperature sensitivity of methanogenesis in a thermokarst lake sediment core

NASA Astrophysics Data System (ADS)

Heslop, J. K.; Walter Anthony, K. M.; Grosse, G.; Anthony, P.; Bondurant, A.

2016-12-01

Little is known about temperature sensitivity of permafrost organic carbon (OC) mineralization over time scales of years to centuries following thaw. Due to their formation and thaw histories, taliks (thaw bulbs) beneath thermokarst lakes provide a unique natural laboratory from which to examine how permafrost thawed in saturated anaerobic conditions responds to changes in temperature following long periods of time since thaw. We anaerobically incubated samples from a 590 cm thermokarst lake sediment core near Fairbanks, Alaska at four temperatures (0, 3, 10, and 25 ºC) bracketing observed talik temperatures. We show that since initial thaw 400 yr BP CH4 production shifts from being most sensitive to at lower (0-3 ºC; Q10-EC=1.15E7) temperatures to being most sensitive at higher (10-25 ºC; Q10-EC=67) temperatures. Frozen sediments collected from beneath the talik, thawed at the commencement of the incubation, had significant (p ≤ 0.05) increases in CH4 production rates at lower temperatures but did not show significant CH4 production rate increases at higher temperatures (10-25 ºC). We hypothesize the thawing of sediments removed a major barrier to C mineralization, leading to rapid initial permafrost C mineralization and preferential mineralization of the most biolabile OC compounds. In contrast, sediments which had been thawed beneath the lake for longer periods of time did not experience statistically significant increases in CH4 production at lower temperatures (0-10 ºC), but had high temperature sensitivities at higher temperatures (10-25 ºC). We believe these rate increases are due to warmer temperatures in the experimental incubations crossing activation energy thresholds, allowing previously recalcitrant fractions of OC to be utilized, and/or the presence of different microbial communities adapted to thawed sediments. Recently-deposited sediments at shallow depths in the lake core experienced increases in CH4 production across all incubation temperatures (Q10-ST=4.4).

Linking Upper Mantle Processes and Long-wavelength Topographic Swells in Cenozoic Africa

NASA Astrophysics Data System (ADS)

Nixon, S.; Maclennan, J.; White, N.; Fishwick, S.

2008-12-01

The topography of present day Africa is influenced by two different wavelengths of dynamic support. The South African Superplume sits beneath Sub-equatorial Africa and is thought to be supported by a lower mantle thermo-chemical anomaly. On a smaller scale a series of topographic domal swells, 1000km in diameter, occur across the continent. The swells are characterised by elevated dynamic topography, a positive long-wavelength gravity anomaly and a negative velocity perturbation from a higher mode surface wave tomography model. In addition, where the lithosphere is thinner than 100km, the swells are capped with volcanic products, erupted periodically since ~30 Ma. These areas include the Cameroon Volcanic line, Hoggar, Tibesti and Darfur in North Africa, and the Ethiopian Plateau and the Kenyan dome found along the East African Rift system. The given relationships suggest the domal swells result from and are supported by upper mantle convection. In order to investigate these relationships a database of 3000 geochemical analyses has been assembled for Cenozoic African volcanism, from both literature search and by new analyses of samples collected from the Al Haruj volcanic field in Libya. Incompatible trace element ratios and REE trends from primitive basalts (>7wt% MgO) erupted less then 10Ma, representing the products of mantle melting, are compared with the upper mantle velocity structure. At depths of 75-100km the greatest velocity perturbation is associated with the Afar/Ethiopia region, where as smaller perturbations are found beneath the North African swells of Hoggar, Tibesti and Darfur. The comparison of absolute velocities, taken from the higher mode tomography model, with trace element ratios has found the low seismic velocity Afar/Ethiopia region to have shallow melting at high melt fractions (La/Yb~9) whereas North African swells with faster seismic velocities at 100 km depth, show deeper melting with smaller melt fractions (La/Yb~30). This positive correlation continues to depths of 150km and is believed to represent variations in mantle potential temperature beneath the African continent. With further modelling of major, trace and REE data we hope to provide insights into variations in mantle potential temperature, melt fraction and velocity structure beneath the topographic swells across the African continent.

Photocopy of photograph (digital image located in LBNL Photo Lab ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Photocopy of photograph (digital image located in LBNL Photo Lab Collection, XBD200503-00117-049). March 2005. TUNNEL ENTRY FROM MAIN FLOOR OF MAGNET ROOM INTO CENTER OF BEVATRON, BENEATH SOUTHWEST QUADRANT - University of California Radiation Laboratory, Bevatron, 1 Cyclotron Road, Berkeley, Alameda County, CA

Reflective Writing: Insights into What Lies beneath

ERIC Educational Resources Information Center

Kathpalia, Sujata S.; Heah, Carmel

2008-01-01

Educationists and writing practitioners consider reflection to be a defining feature of student portfolios (Fink 2003; Zubizarreta 2004; Jones and Shelton 2006). A writing portfolio without reflection is merely a collection of written work which does not contribute to "real" learning. Reflection in the portfolio approach happens when…

Comparison of lichen, conifer needles, passive air sampling devices, and snowpack as passive sampling media to measure semi-volatile organic compounds in remote atmospheres

EPA Science Inventory

The impact of extensively used arsenic-containing herbicides on groundwater beneath golf courses has become a topic of interest. Although currently used organoarsenicals are less toxic, their application into the environment may produce the more toxic inorganic arsenicals. The ob...

Profiling oil sands mixtures from industrial developments and natural groundwaters for source identification.

PubMed

Frank, Richard A; Roy, James W; Bickerton, Greg; Rowland, Steve J; Headley, John V; Scarlett, Alan G; West, Charles E; Peru, Kerry M; Parrott, Joanne L; Conly, F Malcolm; Hewitt, L Mark

2014-01-01

The objective of this study was to identify chemical components that could distinguish chemical mixtures in oil sands process-affected water (OSPW) that had potentially migrated to groundwater in the oil sands development area of northern Alberta, Canada. In the first part of the study, OSPW samples from two different tailings ponds and a broad range of natural groundwater samples were assessed with historically employed techniques as Level-1 analyses, including geochemistry, total concentrations of naphthenic acids (NAs) and synchronous fluorescence spectroscopy (SFS). While these analyses did not allow for reliable source differentiation, they did identify samples containing significant concentrations of oil sands acid-extractable organics (AEOs). In applying Level-2 profiling analyses using electrospray ionization high resolution mass spectrometry (ESI-HRMS) and comprehensive multidimensional gas chromatography time-of-flight mass spectrometry (GC × GC-TOF/MS) to samples containing appreciable AEO concentrations, differentiation of natural from OSPW sources was apparent through measurements of O2:O4 ion class ratios (ESI-HRMS) and diagnostic ions for two families of suspected monoaromatic acids (GC × GC-TOF/MS). The resemblance between the AEO profiles from OSPW and from 6 groundwater samples adjacent to two tailings ponds implies a common source, supporting the use of these complimentary analyses for source identification. These samples included two of upward flowing groundwater collected <1 m beneath the Athabasca River, suggesting OSPW-affected groundwater is reaching the river system.

Three-dimensional structure and seismicity beneath the Central Vanuatu subduction zone

NASA Astrophysics Data System (ADS)

Foix, Oceane; Crawford, Wayne; Pelletier, Bernard; Regnier, Marc; Garaebiti, Esline; Koulakov, Ivan

2017-04-01

The 1400-km long Vanuatu subduction zone results from subduction of the oceanic Australian plate (OAP) beneath the North-Fijian microplate (NFM). Seismic and volcanic activity are both high, and several morphologic features enter into subduction, affecting seismicity and probably plate coupling. The Entrecasteaux Ridge, West-Torres plateau, and Bougainville seamount currently enter into subduction below the large forearc islands of Santo and Malekula. This collision coincides with a strongly decreased local convergence velocity rate - 35 mm/yr compared to 120-160 mm/yr to the north and south - and significant uplift on the overriding plate, indicating a high degree of deformation. The close proximity of large uplifted forearc islands to the trench provides excellent coverage of the megathrust seismogenic zone for a seismological study. We used 10 months of seismological data collected using the 30-instrument land and sea ARC-VANUATU seismology network to construct a 3D velocity model — using the LOTOS joint location/model inversion software — and locate 11655 earthquakes using the NonLinLoc software suite. The 3-D model reveals low P and S velocities in the first tens of kilometers beneath both islands, probably due to water infiltration in the heavily faulted upper plate. The model also suggests the presence of a subducted seamount beneath south Santo. The earthquake locations reveal a complex interaction of faults and stress zones related to high and highly variable deformation. Both brittle deformation and the seismogenic zone depth limits vary along-slab and earthquake clusters are identified beneath central and south Santo, at about 10-30 km of depth, and southwest of Malekula island between 10-20 km depth.

New aerogeophysical data reveal the extent of the Weddell Sea Rift beneath the Institute and Möller ice streams

NASA Astrophysics Data System (ADS)

Jordan, T. A.; Ferraccioli, F.; Siegert, M. J.; Ross, N.; Corr, H.; Bingham, R. G.; Rippin, D. M.; Le Brocq, A. M.

2011-12-01

Significant continental rifting associated with Gondwana breakup has been widely recognised in the Weddell Sea region. However, plate reconstructions and the extent of this rift system onshore beneath the West Antarctic Ice Sheet (WAIS) are ambiguous, due to the paucity of modern geophysical data across the Institute and Möller ice stream catchments. Understanding this region is key to unravelling Gondwana breakup and the possible kinematic links between the Weddell Sea and the West Antarctic Rift System. The nature of the underlying tectonic structure is also critical, as it provides the template for ice-flow draining ~20% of the West Antarctic Ice Sheet (WAIS). During the 2010/11 Antarctic field season ~25,000 km of new airborne radar, aerogravity and aeromagnetic data were collected to help unveil the crustal structure and geological boundary conditions beneath the Institute and Möller ice streams. Our new potential field maps delineate varied subglacial geology beneath the glacial catchments, including Jurassic intrusive rocks, sedimentary basins, and Precambrian basement rocks of the Ellsworth Mountains. Inversion of airborne gravity data reveal significant crustal thinning directly beneath the faster flowing coastal parts of the Institute and Möller ice streams. We suggest that continental rifting focussed along the Weddell Sea margin of the Ellsworth-Whitmore Mountains block, providing geological controls for the fast flowing ice streams of the Weddell Sea Embayment. Further to the south we suggest that strike-slip motion between the East Antarctica and the Ellsworth-Whitmore Mountains block may provide a kinematic link between Cretaceous-Cenozoic extension in the West Antarctic Rift System and deformation in the Weddell Sea Embayment.

Subsurface investigation with ground penetrating radar

USDA-ARS?s Scientific Manuscript database

Ground penetrating radar (GPR) data was collected on a small test plot at the OTF/OSU Turfgrass Research & Education Facility in Columbus, Ohio. This test plot was built to USGA standards for a golf course green, with a constructed sand layer just beneath the surface overlying a gravel layer, that i...

IN-SITU REMEDIATION OF CHROMIUM-CONTAMINATED SOILS AND SEDIMENTS USING SODIUM DITHIONITE

EPA Science Inventory

Soil cores were collected from beneath an old chrome plating shop at the USCG Support Center near Elizabeth City, NC in order to determine the extent of chromium contamination in the soils and ground water. Selective extractions were used to assess the chemical speciation and di...

F-Area Acid/Caustic Basin groundwater monitoring report. First quarter 1995

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

1995-06-01

During first quarter 1995, samples from the FAC monitoring wells at the F-Area Acid/Caustic Basin were collected and analyzed for herbicides/pesticides, indicator parameters, metals, nitrate, radionuclide indicators, volatile organic compounds, and other constituents. Piezometer FAC 5P and monitoring well FAC 6 were dry and could not be sampled. New monitoring wells FAC 9C, 10C, 11C, and 12C were completed in the Barnwell/McBean aquifer and were sampled for the first time during third quarter 1994 (first quarter 1995 is the third of four quarters of data required to support the closure of the basin). Analytical results that exceeded final Primary Drinkingmore » Water Standards (PDWS), other Savannah River Site (SRS) Flag 2 criteria, or the SRS turbidity standard of 50 NTU during the quarter were as follows: gross alpha exceeded the final PDWS and aluminum, iron, manganese, and total alpha-emitting radium exceeded the SRS Flag 2 criteria in one or more of the FAC wells. Turbidity exceeded the SRS standard (50 NTU) in wells FAC 3 and 11C. Groundwater flow direction and rate in the water table beneath the F-Area Acid/Caustic Basin were similar to past quarters.« less

Thermal-Wave Imaging.

ERIC Educational Resources Information Center

Rosencwaig, Allan

1982-01-01

Thermal features of and beneath the surface of a sample can be detected and imaged with a thermal-wave microscope. Various methodologies for the excitation and detection of thermal waves are discussed, and several applications, primarily in microelectronics, are presented. (Author)

Effect of resin coating as a means of preventing marginal leakage beneath full cast crowns.

PubMed

Kosaka, Satomi; Kajihara, Hirotada; Kurashige, Hisanori; Tanaka, Takuo

2005-03-01

The purpose of this study was to evaluate the effectiveness of resin coating as a means of preventing marginal leakage beneath full cast crowns which were emplaced using different cements. Standard full cast crown preparation was made on 64 extracted premolars. These samples were then divided into four groups, with half of each group coated with dentin coating material after preparation. Crowns were cemented onto the teeth using zinc cement, Fuji I, Vitremer, or C&B Metabond. The samples were thermal-cycled for 10,000 cycles. They were then immersed in erythrosine solution, sectioned, and observed under a microscope. Microleakage analyses were performed using a 0-4 point system. The data were statistically analyzed. There were significant differences between the coated specimens and the uncoated specimens using Fuji I and Vitremer. The results showed that a resin coating could decrease the amount of marginal leakage when applied with these two cements.

The method of urine sampling is not a valid predictor for vesicoureteral reflux in children after febrile urinary tract infections.

PubMed

Haid, Bernhard; Roesch, Judith; Strasser, Christa; Oswald, Josef

2017-10-01

The likelihood of detecting vesicoureteral reflux (VUR) after febrile urinary tract infections (UTI) in children logically should correlate with the correct diagnosis of the UTI. Beneath the unspecific symptoms of fever urine analysis is the main diagnostic criterion for the exact diagnosis of febrile UTIs in children. Use of inadequate urine sampling techniques during diagnosis may lead to impaired accuracy in UTI diagnosis. This could lead to the assumption that children, having diagnosed their UTI by the use of possibly inadequate urine sampling techniques should not be evaluated as consequently compared to those, where the diagnosis relied on sterile urine sampling techniques. We hypothesized that children with possibly contaminated urine samples during the initial diagnosis may show a lower rate of VUR in subsequent VCUGs because of a wrong diagnosis initially compared to children, where accurate urine sampling techniques were used. Between 2009 and 2014, a total of 555 patients underwent a primary VCUG at our department indicated because of febrile UTIs. Patients with urine collection methods other than bag urine and catheter/suprapubic aspiration (SPA) were excluded from this study (mid-stream urine, potty urine, n = 149). We evaluated 402 patients (male/female 131/271, mean age 1.91 years), VUR rates and grades were compared between patients where urine was sampled by the use of a urine bag only at the time of diagnosis (n = 296, 73.6%) and those where sterile urine sampling (catheter, suprapubic puncture) was performed (n = 106, 26.3%). 4 patients were excluded due to equivocal data on urine sampling. VUR rate in children after sterile urine sampling using a catheter or SPA accounted to 31.1%. In those where urine samples acquired by the use of urine bags were used, 33.7% showed VUR on subsequent VCUG (p = 0.718). There were no significant differences as to VUR grades or gender, although VUR was much more commonly diagnosed in female patients (37.0% vs 28.2%, p = 0.227) (Figure). Children diagnosed with their UTI by use of bag urine in our experience carried the same risk of showing a VUR in a subsequent VCUG compared to those, where the initial diagnosis relied - beneath clinical criteria - on urine samples acquired by suprapubic puncture or catheterization. Consequently urine-sampling technique during initial UTI diagnosis alone should not be used as predictor for the reliability of UTI diagnosis and should not influence the further management after UTI. Copyright © 2017 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.

BLUE RANGE WILDERNESS, ARIZONA AND NEW MEXICO.

USGS Publications Warehouse

Ratte, James C.; Raabe, R.G.

1984-01-01

A mineral survey of the area was completed and it was determined that a probable resource potential for molybdenum, copper, and silver is present in volcanic rocks of middle Tertiary age in the southern and southwestern parts of the area. There is also a likelihood for the occurrence of base-metal resources (including porphyry copper deposits) of Laramide age beneath the middle Tertiary volcanic rocks that cover the area, but data are insufficient to assess the resource potential. Improved techniques for interpreting geophysical data collected over complex volcanic terranes should be applied in an effort to identify Laramide intrusives beneath the middle Tertiary rocks. Additional geologic studies of the major faults and volcanic centers might enhance mineral-deposit target definition in the middle Tertiary rocks.

Concepts and data-collection techniques used in a study of the unsaturated zone at a low-level radioactive-waste disposal site near Sheffield, Illinois

USGS Publications Warehouse

Healy, R.W.; DeVries, M.P.; Striegl, Robert G.

1986-01-01

A study of water and radionuclide movement through the unsaturated zone is being conducted at the low level radioactive waste disposal site near Sheffield, Illinois. Included in the study are detailed investigations of evapotranspiration, movement of water through waste trench covers, and movement of water and radionuclides (dissolved and gaseous) from the trenches. An energy balance/Bowen ratio approach is used to determine evapotranspiration. Precipitation, net radiation, soil-heat flux, air temperature and water vapor content gradients, wind speed, and wind direction are measured. Soil water tension is measured with tensiometers which are connected to pressure transducers. Meteorological sensors and tensiometers which are connected to pressure transducers. Meteorological sensors and tensiometers are monitored with automatic data loggers. Soil moisture contents are measured through small-diameter access tubes with neutron and gamma-ray attenuation gages. Data beneath the trenches are obtained through a 130-meter-long tunnel which extends under four of the trenches. Water samples are obtained with suction lysimeters, and samples of the geologic material are obtained with core tubes. These samples are analyzed for radiometric and inorganic chemistry. Gas samples are obtained from gas piezometers and analyzed for partial pressures of major constituents, Radon-222, tritiated water vapor, and carbon-14 dioxide. (USGS)

Regional variations in upper mantle compressional velocities beneath southern California 1. Post-shock temperatures: Their experimental determination, calculation, and implications, 2.. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Raikes, S. A.

1978-01-01

The compressional velocity within the upper mantle beneath Southern California is investigated through observations of the dependence of teleseismic P-delays at all stations of the array on the distance and azimuth to the event. The variation of residuals with azimuth was found to be as large as 1.3 sec at a single station; the delays were stable as a function of time, and no evidence was found for temporal velocity variations related to seismic activity in the area. These delays were used in the construction of models for the upper mantle P-velocity structure to depths of 150 km, both by ray tracing and inversion techniques. The models exhibit considerable lateral heterogeneity including a region of low velocity beneath the Imperial Valley, and regions of increased velocity beneath the Sierra Nevada and much of the Transverse Ranges. The development is described of a technique for the experimental determination of post-shock temperatures, and its application to several metals and silicates shocked to pressures in the range 5 to 30 GPa. The technique utilizes an infra-red radiation detector to determine the brightness temperature of the free surface of the sample after the shock wave has passed through it.

Archive of Digital Boomer and CHIRP Seismic Reflection Data Collected During USGS Field Activity 08LCA03 in Lake Panasoffkee, Florida, May 2008

USGS Publications Warehouse

Harrison, Arnell S.; Dadisman, Shawn V.; McBride, W. Scott; Flocks, James G.; Wiese, Dana S.

2009-01-01

In May of 2008, the U.S. Geological Survey (USGS) conducted geophysical surveys in Lake Panasoffkee, located in central Florida, as part of the USGS Lakes and Coastal Aquifers (LCA) study. This report serves as an archive of unprocessed digital boomer and Compressed High Intensity Radar Pulse (CHIRP)* seismic reflection data, trackline maps, navigation files, Field Activity Collection System (FACS) logs, Geographic Information System (GIS) files, and formal Federal Geographic Data Committee (FGDC) metadata. Filtered and gained (a relative increase in signal amplitude) digital images of the seismic profiles and geospatially corrected interactive profiles are also provided. Refer to the Acronyms page for expansions of acronyms and abbreviations used in this report. *Due to poor data acquisition conditions associated with the lake bottom sediments, only two CHIRP tracklines were collected during this field activity. The archived trace data are in standard Society of Exploration Geophysicists (SEG) SEG-Y format (Barry and others, 1975) and may be downloaded and processed with commercial or public domain software such as Seismic Unix (SU). Example SU processing scripts and USGS software for viewing the SEG-Y files (Zihlman, 1992) are provided. The USGS Florida Integrated Science Center (FISC) - St. Petersburg assigns a unique identifier to each cruise or field activity. For example, 08LCA03 tells us the data were collected in 2008 for the Lakes and Coastal Aquifers (LCA) study and the data were collected during the third field activity for that study in that calendar year. Refer to http://walrus.wr.usgs.gov/infobank/programs/html/definition/activity.html for a detailed description of the method used to assign the field activity ID. The naming convention used for each seismic line is as follows: yye##a, where 'yy' are the last two digits of the year in which the data were collected, 'e' is a 1-letter abbreviation for the equipment type (for example, b for boomer and c for CHIRP), '##' is a 2-digit number representing a specific track, and 'a' is a letter representing the section of a line if recording was prematurely terminated or rerun for quality or acquisition problems. The boomer plate is an acoustic energy source that consists of capacitors charged to a high voltage and discharged through a transducer in the water. The transducer is towed on a sled floating on the water surface and, when discharged, emits a short acoustic pulse, or shot, which propagates through the water, sediment column, or rock beneath. The acoustic energy is reflected at density boundaries (such as the seafloor, sediment, or rock layers beneath the seafloor), detected by the receiver, and recorded by a PC-based seismic acquisition system. This process is repeated at timed intervals (for example, 0.5 s) and recorded for specific intervals of time (for example, 100 ms). In this way, a two-dimensional (2-D) vertical profile of the shallow geologic structure beneath the ship track is produced. Figure 1 displays the boomer acquisition geometry. The EdgeTech SB-424 CHIRP system used for this survey has a vertical resolution of 4 - 8 cm, a penetration depth that is usually less than 2 m beneath the seafloor, and uses a signal of continuously varying frequency. The towfish is a sound source and receiver, which is typically towed 2 - 5 m above the seafloor. The acoustic energy is reflected at density boundaries (such as the seafloor or sediment layers beneath the seafloor), detected by a receiver, and recorded by a PC-based seismic acquisition system. This process is repeated at timed intervals (for example, 0.125 s) and recorded for specific intervals of time (for example, 50 ms); the resulting profile is a two-dimensional vertical image of the shallow geologic structure beneath the ship track. Figure 2 displays the acquisition geometry for the CHIRP system. Refer to table 1 for a summary of acquisition parameters and table 2 for trackline statistics.

Detection of latent bloodstains beneath painted surfaces using reflected infrared photography.

PubMed

Farrar, Andrew; Porter, Glenn; Renshaw, Adrian

2012-09-01

Bloodstain evidence is a highly valued form of physical evidence commonly found at scenes involving violent crimes. However, painting over bloodstains will often conceal this type of evidence. There is limited research in the scientific literature that describes methods of detecting painted-over bloodstains. This project employed a modified digital single-lens reflex camera to investigate the effectiveness of infrared (IR) photography in detecting latent bloodstain evidence beneath a layer or multiple layers of paint. A qualitative evaluation was completed by comparing images taken of a series of samples using both IR and standard (visible light) photography. Further quantitative image analysis was used to verify the findings. Results from this project indicate that bloodstain evidence can be detected beneath up to six layers of paint using reflected IR; however, the results vary depending on the characteristics of the paint. This technique provides crime scene specialists with a new field method to assist in locating, visualizing, and documenting painted-over bloodstain evidence. © 2012 American Academy of Forensic Sciences.

Groundwater and Leachate Monitoring and Sampling at ERDF, CY 2006

DOE Office of Scientific and Technical Information (OSTI.GOV)

R. L. Weiss

2007-12-05

The purpose of this annual monitoring report is to evaluate the conditions of and identify trends for groundwater beneath the ERDF and to report leachate results in fulfillment of the requirements specified in the ERDF ROD.

Groundwater and Leachate Monitoring and Sampling at ERDF, CY 2006

DOE Office of Scientific and Technical Information (OSTI.GOV)

R. L. Weiss

2007-05-30

The purpose of this annual monitoring report is to evaluate the conditions of and identify trends for groundwater beneath the ERDF and to report leachate results in fulfillment of the requirements specified in the ERDF ROD.

The Brava seamount, Cape Verde: Beyond the spatial extent of EM1 and petrogenesis of highly evolved alkaline lavas.

NASA Astrophysics Data System (ADS)

Barker, Abigail; Andersson, Axel; Troll, Valentin; Hansteen, Thor; Ellam, Robert

2010-05-01

Alkaline lavas from the Brava seamount, Cape Verde are investigated to establish the spatial distribution of compositional heterogeneity in the southwest of the Cape Verde archipelago. Highly evolved lavas provide a record of shallow level magma-crust interaction beneath the Brava seamount. The Brava seamount, located southwest of the island of Brava, Cape Verde was sampled during research cruise 8/85 of the R.R.S. Charles Darwin in 1985. Two groups of highly evolved alkaline volcanics are distinguished from the Brava seamount: 1) pyroxene-phonolites containing clinopyroxene, amphibole, nepheline, ±biotite, and minor sanidine and 2) feldspathoid-phonolites containing nepheline, nausean, minor biotite and leucite. All of the samples have MgO between 0.8 and 2 wt%, comparable to the most evolved volcanics sampled in the Cape Verde archipelago. The feldspathoid-phonolites have NaO2 of 12-13 wt%. Alkaline lavas from the Brava seamount have higher 87Sr/87Sr (0.70337 to 0.70347) at ɛNd of +6 to +7 than previously sampled in Cape Verde. Sr isotopes will be integrated with oxygen isotopes to establish magma and crust interactions in the magmatic plumbing system beneath the Brava seamount. Clinopyroxene-melt thermobarometry will be presented to constrain the depths of equilibrium crystallisation. Sr-O isotopes and thermobarometry will be combined to build a picture of the levels of magma stalling and interaction between magmas and the crust beneath the Brava seamount. The Brava seamount phonolitic lavas have high 206Pb/204Pb of 19.5 to 19.8 with negative ?8/4 and high ɛNd of +6 to +7 in contrast to the positive ?8/4 for lavas from nearby Brava and the southern islands of the Cape Verde archipelago. Lavas from the Brava seamount have Pb-Nd isotope systematics comparable to the northern Cape Verde islands, indicating the southwestern boundary in mantle heterogeneity and thereby the spatial extent of the EM1-like source contributing to the southern islands. The extensive crystallisation and stalling of magma batches at crustal depths shown by thermobarometry will be used in conjunction with geochemistry to constrain the origin of assimilants and implies that an EM1-like source is not found in the mantle source, the shallow lithosphere or crust beneath the Brava seamount.

Detrital zircon and apatite (U-Th)/He geochronology of intercalated baked sediments: A new approach to dating young basalt flows

NASA Astrophysics Data System (ADS)

Cooper, Frances J.; van Soest, Matthijs C.; Hodges, Kip V.

2011-07-01

Simple numerical models suggest that many basaltic lava flows should sufficiently heat the sediments beneath them to reset (U-Th)/He systematics in detrital zircon and apatite. This result suggests a useful way to date such flows when more conventional geochronological approaches are either impractical or yield specious results. We present here a test of this method on sediments interstratified with basalt flows of the Taos Plateau Volcanic Field of New Mexico. Nineteen zircons and apatites from two samples of baked sand collected from the uppermost 2 cm of a fluvial channel beneath a flow of the Upper Member of the Servilleta Basalt yielded an apparent age of 3.487 ± 0.047 Ma (2 SE confidence level), within the range of all published 40Ar/39Ar dates for other flows in the Upper Member (2.81-3.72 Ma) and statistically indistinguishable from the 40Ar/39Ar dates for basal flows of the Upper Member with which the studied flow is broadly correlative (3.61 ± 0.13 Ma). Given the high yield of 4He from U and Th decay, this technique may be especially useful for dating Pleistocene basalt flows. Detailed studies of the variation of (U-Th)/He detrital mineral dates in sedimentary substrates, combined with thermal modeling, may be a valuable tool for physical volcanologists who wish to explore the temporal and spatial evolution of individual flows and lava fields.

The Determination of Soil-plant Transfer Coefficients of Cesium-137 and Other Elements by γ-Ray Measurement and PIXE Analysis, for use in the Remediation of Fukushima

NASA Astrophysics Data System (ADS)

Ishii, K.; Fujita, A.; Toyama, S.; Terakawa, A.; Matsuyama, S.; Arai, H.; Osada, N.; Takyu, S.; Matsuyama, T.; Koshio, S.; Watanabe, K.; Ito, S.; Kasahara, K.

Edible wild plants growing in the area around the Fukushima Daiichi nuclear power plant remain contaminated. It is important to identify plants with low levels of contamination for the restoration of agriculture in the area. We collected specimens of 10 wild plant species growing in Iitate village which is one of the most highly contaminated areas and also sampled the soil beneath each plant. We measured the specific activity of 137Cs and the concentrations of Na, Mg, Al, Si, P, S, K, Ca, Fe, Zn, Rb and Sr in these samples using a germanium detector and PIXE analysis, respectively. We compared the soil-plant transfer coefficient of 137Cs with those of each element and determined their correlation with 137Cs. It was found that a low Sr transfer coefficient could be used to determine the plants with a low 137Cs transfer coefficient. We suggest that PIXE analysis is a useful analysis technique for agricultural remediation projects in highly contaminated areas around the Fukushima Daiichi nuclear power plant.

Using luminescence dating of coarse matrix material to estimate the slip rate of the Astaneh fault, Iran

USGS Publications Warehouse

Rizza, M.; Mahan, S.; Ritz, J.-F.; Nazari, H.; Hollingsworth, J.; Salamati, R.

2011-01-01

In this paper, we present optically and infrared stimulated luminescence (OSL and IRSL) ages for four samples from alluvial fan surfaces in the Astaneh Valley. This valley is located in the north-east part of the Alborz range in Iran. Our morphologic interpretations recognize at least three generations of fans in the study area, all of which have been displaced along the left-lateral strike-slip Astaneh fault. Because of the dry, loose, and sometimes complex juxtaposition of the target sediments, we collected the samples in total darkness beneath dark plastic layers placed atop the pit openings. Luminescence ages of the fans are ???55 ka, ???32 ka and ???16 ka. These ages are concurrent with periods of loess deposition and wet climatic conditions previously recorded in the Arabia-Iranian region. They allow estimation of a horizontal slip rate of ???2 mm/yr along the Astaneh fault, which is consistent with additional slip rates determined for the Holocene period along faults further west of the Astaneh fault. ?? 2011 Elsevier B.V.

Electrostatic discharge test apparatus

NASA Technical Reports Server (NTRS)

Smith, William C. (Inventor)

1989-01-01

Electrostatic discharge properties of materials are quantitatively measured and ranked. Samples (20) are rotated on a turntable (15) beneath selectable, co-available electrostatic chargers (30/40), one being a corona charging element (30) and the other a sample-engaging triboelectric charging element (40). They then pass under a voltage meter (25) to measure the amount of residual charge on the samples (20). After charging is discontinued, measurements are continued to record the charge decay history over time.

Early Pleistocene(?) pollen spectra from near Lake Tahoe, California

USGS Publications Warehouse

Adam, David P.

1973-01-01

Fossil pollen was recovered at Tahoe City, Calif., from beneath a 1.9-m.y.-old volcanic flow. Pollen counts of four fossil samples are compared with soil-surface pollen samples from the Sierra Nevada. The presence of Picea (spruce) pollen in the fossil samples suggests that summer drought conditions in the central Sierra Nevada were less severe prior to 1.9 m.y. ago than they are now.

Ground-water hydrology and water quality of Irwin Basin at Fort Irwin National Training Center, California

USGS Publications Warehouse

Densmore, Jill N.; Londquist, Clark J.

1997-01-01

Geohydrologic data were collected from Irwin Basin at Fort Irwin National Training Center in the Mojave Desert of southern California by the U.S. Geological Survey during 199296 to deter mine the quantity and quality of ground water available in this basin. In addition to data collected from existing wells and test holes, 17 monitoring sites were constructed in Irwin Basin to provide data on subsurface geology, ground-water levels, and ground-water quality. Eleven of these sites were multiple-well monitoring sites that were constructed to provide depth-dependent geohydrologic data in the aquifer system. The aquifer system of Irwin Basin, defined on the basis of hydrologic data collected from wells in Irwin Basin, consists of an upper and a lower aquifer. A 1994 water-table contour map shows that a cone of depression beneath Irwin Basin well field has developed as a result of ground-water development. Water-quality samples collected from Irwin Basin wells to determine potential sources of ground-water degradation indicate that water in three areas in the basin contains high nitrate and dissolved-solids concentrations. The stable isotopes of oxygen and hydrogen indicate that present-day precipitation is not a major source of recharge in this basin. Tritium and carbon-14 data indicate that most of the basin was recharged before 1953 and that this water may be more than 14,000 years old.

Modeling of U-series Radionuclide Transport Through Soil at Pena Blanca, Chihuahua, Mexico

NASA Astrophysics Data System (ADS)

Pekar, K. E.; Goodell, P. C.; Walton, J. C.; Anthony, E. Y.; Ren, M.

2007-05-01

The Nopal I uranium deposit is located at Pena Blanca in Chihuahua, Mexico. Mining of high-grade uranium ore occurred in the early 1980s, with the ore stockpiled nearby. The stockpile was mostly cleared in the 1990s; however, some of the high-grade boulders have remained there, creating localized sources of radioactivity for a period of 25-30 years. This provides a unique opportunity to study radionuclide transport, because the study area did not have any uranium contamination predating the stockpile in the 1980s. One high-grade boulder was selected for study based upon its shape, location, and high activity. The presumed drip-line off of the boulder was marked, samples from the boulder surface were taken, and then the boulder was moved several feet away. Soil samples were taken from directly beneath the boulder, around the drip-line, and down slope. Eight of these samples were collected in a vertical profile directly beneath the boulder. Visible flakes of boulder material were removed from the surficial soil samples, because they would have higher concentrations of U-series radionuclides and cause the activities in the soil samples to be excessively high. The vertical sampling profile used 2-inch thicknesses for each sample. The soil samples were packaged into thin plastic containers to minimize the attenuation and to standardize sample geometry, and then they were analyzed by gamma-ray spectroscopy with a Ge(Li) detector for Th-234, Pa-234, U-234, Th-230, Ra-226, Pb-214, Bi-214, and Pb-210. The raw counts were corrected for self-attenuation and normalized using BL-5, a uranium standard from Beaverlodge, Saskatchewan. BL-5 allowed the counts obtained on the Ge(Li) to be referenced to a known concentration or activity, which was then applied to the soil unknowns for a reliable calculation of their concentrations. Gamma ray spectra of five soil samples from the vertical profile exhibit decreasing activities with increasing depth for the selected radionuclides. Independent multi-element analyses of three samples by ICP-MS show decreasing uranium concentration with depth as well. The transport of the radionuclides is evaluated using STANMOD, a Windows-based software package for evaluating solute transport in porous media using analytical solutions of the advection-dispersion solute transport equation. The package allows various one-dimensional, advection-dispersion parameters to be determined by fitting mathematical solutions of theoretical transport models to observed data. The results are promising for future work on the release rate of radionuclides from the boulder, the dominant mode of transport (e.g., particulate or dissolution), and the movement of radionuclides through porous media. The measured subsurface transport rates provide modelers with a model validation dataset.

Stable isotope (2H, 17O, 18O) and hydro chemical patterns of precipitation collected in weekly resolution at Hannover, Germany

NASA Astrophysics Data System (ADS)

Koeniger, Paul; Himmelsbach, Thomas

2016-04-01

Long-term observations of stable isotopes (δ18O and δ2H) in precipitation were initiated in May 2008 at the Federal Institute of Geosciences and Natural Resources (BGR) in Hannover, Germany. In 2014 all precipitation samples were re-analyzed because a purchase of a new laser spectrometer (Picarro L2140-i) now allowed measurements of δ17O and a calculation of the 17O-excess parameter. Starting in October 2015 a routine analysis of hydro chemical parameters was added whenever enough sample aliquot was available (major ions, trace elements). A discussion of the stable isotope data of the seven year series of weekly precipitation samples (n = 370) will be presented. Beneath general patterns (seasonality and trends) we also focus on importance of amount weighing procedures, corrections for minor rain amounts, aspects of sample storage and re-analyzes, as well as impacts through changes in analytical equipment (IRMS, CRD spectroscopy) which is visible from the data. For stable isotopes a Thermo Fisher delta plus IRMS (Gasbench and H-Device) was used until 2011 and from 2012 on a Picarro L2120-i water vapor analyzer with long-term accuracies for quality check samples better than 0.2‰ and 0.8‰ for δ18O and δ2H, respectively.

Bacterial selection by mycospheres of Atlantic Rainforest mushrooms.

PubMed

Halsey, Joshua Andrew; de Cássia Pereira E Silva, Michele; Andreote, Fernando Dini

2016-10-01

This study focuses on the selection exerted on bacterial communities in the mycospheres of mushrooms collected in the Brazilian Atlantic Rainforest. A total of 24 paired samples (bulk soil vs. mycosphere) were assessed to investigate potential interactions between fungi and bacteria present in fungal mycospheres. Prevalent fungal families were identified as Marasmiaceae and Lepiotaceae (both Basidiomycota) based on ITS partial sequencing. We used culture-independent techniques to analyze bacterial DNA from soil and mycosphere samples. Bacterial communities in the samples were distinguished based on overall bacterial, alphaproteobacterial, and betaproteobacterial PCR-DGGE patterns, which were different in fungi belonging to different taxa. These results were confirmed by pyrosequencing the V4 region of the 16S rRNA gene (based on five bulk soil vs. mycosphere pairs), which revealed the most responsive bacterial families in the different conditions generated beneath the mushrooms, identified as Bradyrhizobiaceae, Burkholderiaceae, and Pseudomonadaceae. The bacterial families Acetobacteraceae, Chrhoniobacteraceae, Planctomycetaceae, Conexibacteraceae, and Burkholderiaceae were found in all mycosphere samples, composing the core mycosphere microbiome. Similarly, some bacterial groups identified as Koribacteriaceae, Acidobacteria (Solibacteriaceae) and an unclassified group of Acidobacteria were preferentially present in the bulk soil samples (found in all of them). In this study we depict the mycosphere effect exerted by mushrooms inhabiting the Brazilian Atlantic Rainforest, and identify the bacteria with highest response to such a specific niche, possibly indicating the role bacteria play in mushroom development and dissemination within this yet-unexplored environment.

Human enteric viruses in groundwater from a confined bedrock aquifer

USGS Publications Warehouse

Borchardt, M. A.; Bradbury, K.R.; Gotkowitz, M.B.; Cherry, J.A.; Parker, B.L.

2007-01-01

Confined aquifers are overlain by low-permeability aquitards that are commonly assumed to protect underlying aquifers from microbial contaminants. However, empirical data on microbial contamination beneath aquitards is limited. This study determined the occurrence of human pathogenic viruses in well water from a deep sandstone aquifer confined by a regionally extensive shale aquitard. Three public water-supply wells were each sampled 10 times over 15 months. Samples were analyzed by reverse transcription-polymerase chain reaction (RT-PCR) for several virus groups and by cell culture for infectious enteroviruses. Seven of 30 samples were positive by RT-PCR for enteroviruses; one of these was positive for infectious echovirus 18. The virus-positive samples were collected from two wells cased through the aquitard, indicating the viruses were present in the confined aquifer. Samples from the same wells showed atmospheric tritium, indicating water recharged within the past few decades. Hydrogeologic conditions support rapid porous media transport of viruses through the upper sandstone aquifer to the top of the aquitard 61 m below ground surface. Natural fractures in the shale aquitard are one possible virus transport pathway through the aquitard; however, windows, cross-connecting well bores, or imperfect grout seals along well casings also may be involved. Deep confined aquifers can be more vulnerable to contamination by human viruses than commonly believed. ?? 2007 American Chemical Society.

Pre-Columbian archaeological ruins are revealed through Costa Rican rain forest in this photo taken during NASA's AirSAR 2004 campaign

NASA Image and Video Library

2004-03-05

Pre-Columbian archaeological ruins are revealed through Costa Rican rain forest in this photo taken during NASA's AirSAR 2004 Mesoamerica campaign. AirSAR 2004 Mesoamerica is a three-week expedition by an international team of scientists that uses an all-weather imaging tool, called the Airborne Synthetic Aperture Radar (AirSAR) which is located onboard NASA's DC-8 airborne laboratory. The radar, developed by NASA's Jet Propulsion Laboratory, can penetrate clouds and also collect data at night. Its high-resolution sensors operate at multiple wavelengths and modes, allowing AirSAR to see beneath treetops, through thin sand, and dry snow pack. Much of the archaeological evidence needed to understand Pre-Columbian societies in Central America comes from features on the landscape. Difficult terrain and logistics have limited ground data collection. AirSAR helped to detect signs of ancient civilizations hidden beneath the forest. Its images will shed insights into the way modern humans interact with their landscape, and how ancient peoples lived and what became of their civilizations.

Surface-Water Exchange through Culverts beneath State Road 9336 within Everglades National Park, 2004-05

USGS Publications Warehouse

Schaffranek, Raymond W.; Stewart, Marc A.; Nowacki, Daniel J.

2008-01-01

The U.S. Geological Survey collected hydrologic data between June 2004 and December 2005 to investigate the temporal and spatial nature of flow exchanges through culverts beneath State Road 9336 within Everglades National Park. Continuous data collected during the study measured flow velocity, water level, salinity, conductivity, and water-temperature in or near seven culverts between Pa-hay-okee Overlook access road and Nine Mile Pond. The two culverts east of Pa-hay-okee Overlook access road flowed into Taylor Slough Basin from 87 to 96 percent of the study period, whereas flows through five culverts between Pa-hay-okee Overlook access road and Nine Mile Pond flowed into Shark River Slough Basin from 70 to 99 percent of the study period. Synoptic flow discharges measured at all culverts during three intensive field efforts revealed a net discharge into Taylor Slough Basin from Shark River Slough Basin through culverts between Royal Palm Road and Pa-hay-okee Overlook access road, and into Shark River Slough Basin from Taylor Slough Basin through culverts between Pa-hay-okee Overlook access road and Nine Mile Pond. Data collected during the study and presented in this report provided additional knowledge of the magnitude, direction, and nature of flow exchanges through the road culverts.

Deforestation and Malaria on the Amazon Frontier: Larval Clustering of Anopheles darlingi (Diptera: Culicidae) Determines Focal Distribution of Malaria

PubMed Central

Barros, Fábio S. M.; Honório, Nildimar A.

2015-01-01

We performed bimonthly mosquito larval collections during 1 year, in an agricultural settlement in the Brazilian Amazon, as well as an analysis of malaria incidence in neighboring houses. Water collections located at forest fringes were more commonly positive for Anopheles darlingi larvae and Kulldorff spatial analysis pinpointed significant larval clusters at sites directly beneath forest fringes, which were called larval “hotspots.” Remote sensing identified 43 “potential” hotspots. Sampling of these areas revealed an 85.7% positivity rate for A. darlingi larvae. Malaria was correlated with shorter distances to potential hotpots and settlers living within 400 m of potential hotspots had a 2.60 higher risk of malaria. Recently arrived settlers, usually located closer to the tip of the triangularly shaped deforestation imprints of side roads, may be more exposed to malaria due to their proximity to the forest fringe. As deforestation progresses, transmission decreases. However, forest remnants inside deforested areas conferred an increased risk of malaria. We propose a model for explaining frontier malaria in the Amazon: because of adaptation of A. darlingi to the forest fringe ecotone, humans are exposed to an increased transmission risk when in proximity to these areas, especially when small dams are created on naturally running water collections. PMID:26416110

Investigating Seed Longevity of Big Sagebrush (Artemisia tridentata)

USGS Publications Warehouse

Wijayratne, Upekala C.; Pyke, David A.

2009-01-01

The Intermountain West is dominated by big sagebrush communities (Artemisia tridentata subspecies) that provide habitat and forage for wildlife, prevent erosion, and are economically important to recreation and livestock industries. The two most prominent subspecies of big sagebrush in this region are Wyoming big sagebrush (A. t. ssp. wyomingensis) and mountain big sagebrush (A. t. ssp. vaseyana). Increased understanding of seed bank dynamics will assist with sustainable management and persistence of sagebrush communities. For example, mountain big sagebrush may be subjected to shorter fire return intervals and prescribed fire is a tool used often to rejuvenate stands and reduce tree (Juniperus sp. or Pinus sp.) encroachment into these communities. A persistent seed bank for mountain big sagebrush would be advantageous under these circumstances. Laboratory germination trials indicate that seed dormancy in big sagebrush may be habitat-specific, with collections from colder sites being more dormant. Our objective was to investigate seed longevity of both subspecies by evaluating viability of seeds in the field with a seed retrieval experiment and sampling for seeds in situ. We chose six study sites for each subspecies. These sites were dispersed across eastern Oregon, southern Idaho, northwestern Utah, and eastern Nevada. Ninety-six polyester mesh bags, each containing 100 seeds of a subspecies, were placed at each site during November 2006. Seed bags were placed in three locations: (1) at the soil surface above litter, (2) on the soil surface beneath litter, and (3) 3 cm below the soil surface to determine whether dormancy is affected by continued darkness or environmental conditions. Subsets of seeds were examined in April and November in both 2007 and 2008 to determine seed viability dynamics. Seed bank samples were taken at each site, separated into litter and soil fractions, and assessed for number of germinable seeds in a greenhouse. Community composition data from each site, as well as several environmental variables, were used to evaluate seed viability within the context of habitat variation. Initial viability of seeds used in the seed retrieval experiment was 81 and 92 percent for mountain and Wyoming big sagebrush, respectively. After remaining in the field for 24 months, buried Wyoming big sagebrush seeds retained 28-58 percent viability,11-23 percent of seeds under litter remained viable, and no seeds remained viable on the surface (estimates are 95-percent confidence intervals). The odds of remaining viable did not change from 12 to 24 months. However, after 24 months the odds of seeds beneath litter being viable decreased to 75 percent of the odds of viability at 12 months. Similar to Wyoming big sagebrush, buried seeds of mountain big sagebrush were 31-68 percent viable, seeds under litter retained 10-22 percent of their viability, and no surface seeds were viable after 24 months. Both subspecies of big sagebrush had some portion of seed that remained viable for more than one growing season provided they were buried or under litter. Although seeds beneath litter may remain viable in intact communities, seeds are susceptible to incineration during fires. Nine months after seed dispersal, seed bank estimates for Wyoming big sagebrush ranged from 19 to 49 viable seeds/m2 in litter samples and 19-57 viable seeds/m2 in soil samples (95-percent confidence interval). For mountain big sagebrush, estimates were 27-75 viable seeds/m2 in litter samples and 54-139 viable seeds/m2 in soil (95-percent confidence interval). The number of viable seeds present in the seed bank 9 months after seed dispersal was not significantly different from the number present immediately after seed dispersal. Seed viability was highest in mountain big sagebrush sites for seeds on the surface and beneath litter, but decreased after one season. Buried seeds of both subspecies were in equal abundances and may be insulated from the effect

Interpretation of stable isotope, denitrification, and groundwater age data for samples collected from Sandia National Laboratories /New Mexico (SNL/NM) Burn Site Groundwater Area of Concern

DOE Office of Scientific and Technical Information (OSTI.GOV)

Madrid, V.; Singleton, M. J.; Visser, A.

This report combines and summarizes results for two groundwater-sampling events (October 2012 and October/November 2015) from the Sandia National Laboratories/New Mexico (SNL/NM) Burn Site Groundwater (BSG) Area of Concern (AOC) located in the Lurance Canyon Arroyo southeast of Albuquerque, NM in the Manzanita Mountains. The first phase of groundwater sampling occurred in October 2012 including samples from 19 wells at three separate sites that were analyzed by the Environmental Radiochemistry Laboratory at Lawrence Livermore National Laboratory as part of a nitrate Monitored Natural Attenuation (MNA) evaluation. The three sites (BSG, Technical Area-V, and Tijeras Arroyo) are shown on the regionalmore » hydrogeologic map and described in the Sandia Annual Groundwater Monitoring Report. The first phase of groundwater sampling included six monitoring wells at the Burn Site, eight monitoring wells at Technical Area-V, and five monitoring wells at Tijeras Arroyo. Each groundwater sample was analyzed using the two specialized analytical methods, age-dating and denitrification suites. In September 2015, a second phase of groundwater sampling took place at the Burn Site including 10 wells sampled and analyzed by the same two analytical suites. Five of the six wells sampled in 2012 were resampled in 2015. This report summarizes results from two sampling events in order to evaluate evidence for in situ denitrification, the average age of the groundwater, and the extent of recent recharge of the bedrock fracture system beneath the BSG AOC.« less

Refining the site conceptual model at a former uranium mill site in Riverton, Wyoming, USA

DOE PAGES

Dam, William; Campbell, Sam; Johnson, Ray; ...

2015-07-07

Milling activities at a former uranium mill site near Riverton, Wyoming, USA, contaminated the shallow groundwater beneath and downgradient of the site. Although the mill operated for <6 years (1958-1963), its impact remains an environmental liability. Groundwater modeling predicted that contaminant concentrations were declining steadily, which confirmed the conceptual site model (CSM). However, local flooding in 2010 mobilized contaminants that migrated downgradient from the Riverton site and resulted in a dramatic increase in groundwater contaminant concentrations. This observation indicated that the original CSM was inadequate to explain site conditions and needed to be refined. In response to the new observationsmore » after the flood, a collaborative investigation to better understand site conditions and processes commenced. This investigation included installing 103 boreholes to collect soil and groundwater samples, sampling and analysis of evaporite minerals along the bank of the Little Wind River, an analysis of evaportranspiration in the shallow aquifer, and sampling naturally organic-rich sediments near groundwater discharge areas. The enhanced characterization revealed that the existing CSM did not account for high uranium concentrations in groundwater remaining on the former mill site and groundwater plume stagnation near the Little Wind River. Observations from the flood and subsequent investigations indicate that additional characterization is still needed to continue refining the CSM and determine the viability of the natural flushing compliance strategy. Additional sampling, analysis, and testing of soil and groundwater are necessary to investigate secondary contaminant sources, mobilization of contaminants during floods, geochemical processes, contaminant plume stagnation, distribution of evaporite minerals and organic-rich sediments, and mechanisms and rates of contaminant transfer from soil to groundwater. Future data collection will be used to continually revise the CSM and evaluate the compliance strategy at the site.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Last, G.V.; Eddy, P.A.; Airhart, S.P.

The information presented in this report was collected during limited site investigation activities conducted in the vicinity of Landfills 1 and 4 at Fort Lewis. The purpose of this work was to provide a means of detecting and evaluating the impacts of these inactive landfills on ground-water quality and adjacent lands. This effort included the design and construction of ground-water monitoring systems for compliance with applicable federal and state regulations governing Resource Conservation and Recovery Act (RCRA)-type landfills. Ground-water samples were collected from both existing (1981 and 1984) wells and the newly installed (1988) wells. The analytical results from themore » water samples indicate that the ground water in and around Landfill 1 contains limited contamination. Contaminants may include volatile organic compounds and nitrate. The primary concern in the area around Landfill 1 was the determination that ground water from two wells may contain cis-1,2-dichloroethylene and 1,1,1-trichloroethylene above drinking water standards. Nitrate levels in the downgradient wells were greater than those in upgradient wells and exceeded drinking water standards in some of the less-representative samples. Analyses of ground-water samples from wells in and around Landfill 4 indicate several contaminants may be present. These include volatile organic compounds (principally cis-1,2-dichloroethylene and 1,1,1-trichloroethylene), coliform, oil and grease, and perhaps some metals (iron and magnesium). The primary concern in the area around Landfill 4 was the determination that ground water from five wells contained cis-1,2-dichloroethylene and 1,1,1-trichloroethylene above drinking water standards. The source of contaminants beneath either landfill cannot yet be identified. Insufficient data exist to disprove or confirm either landfill as possible contributors. 19 refs., 32 figs., 17 tabs.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dam, William; Campbell, Sam; Johnson, Ray

Milling activities at a former uranium mill site near Riverton, Wyoming, USA, contaminated the shallow groundwater beneath and downgradient of the site. Although the mill operated for <6 years (1958-1963), its impact remains an environmental liability. Groundwater modeling predicted that contaminant concentrations were declining steadily, which confirmed the conceptual site model (CSM). However, local flooding in 2010 mobilized contaminants that migrated downgradient from the Riverton site and resulted in a dramatic increase in groundwater contaminant concentrations. This observation indicated that the original CSM was inadequate to explain site conditions and needed to be refined. In response to the new observationsmore » after the flood, a collaborative investigation to better understand site conditions and processes commenced. This investigation included installing 103 boreholes to collect soil and groundwater samples, sampling and analysis of evaporite minerals along the bank of the Little Wind River, an analysis of evaportranspiration in the shallow aquifer, and sampling naturally organic-rich sediments near groundwater discharge areas. The enhanced characterization revealed that the existing CSM did not account for high uranium concentrations in groundwater remaining on the former mill site and groundwater plume stagnation near the Little Wind River. Observations from the flood and subsequent investigations indicate that additional characterization is still needed to continue refining the CSM and determine the viability of the natural flushing compliance strategy. Additional sampling, analysis, and testing of soil and groundwater are necessary to investigate secondary contaminant sources, mobilization of contaminants during floods, geochemical processes, contaminant plume stagnation, distribution of evaporite minerals and organic-rich sediments, and mechanisms and rates of contaminant transfer from soil to groundwater. Future data collection will be used to continually revise the CSM and evaluate the compliance strategy at the site.« less

Lithospheric structure beneath Mainland China from ambient noise tomography

NASA Astrophysics Data System (ADS)

Huang, J.; Peng, J.; Liu, Z.

2017-12-01

The Chinese continent is composed of several Precambrian craton blocks and Phanerozoic orogenic belts. To better understand the complex geological structure and tectonic evolution, it is important to develop a high-resolution shear velocity model of the lithosphere. In this study, we try to use ambient noise tomography to image the lithospheric structure beneath mainland China. However, in contrast with most of the existing ambient noise tomography studies which focus on the surface wave at periods shorter than 60 s, we apply the technique of phase-weighted stack (PWS) (Schimmel et al., 2011) when stacking the cross-correlations of ambient noise. We could extract long-period ( 125 s) dispersions to image the high-resolution lithospheric structure. We collected continuous seismic records from the broadband stations of China Regional Seismic Networks and NECESSArray between Sept., 2009 and Aug., 2011. We constructed Rayleigh wave group and phase velocity maps on 0.25 ×0.25 degree grids, and then inverted a high-resolution lithospheric 3D shear velocity model up to 150 km depth. The results exhibited pronounced lateral heterogeneity of the lithospheric structure of the study area. It is obvious that the high velocities beneath the Ordos and Sichuan Basin exceeds 150 km, representing the strong and thick lithosphere. The lithospheric thickness gradually thins from west to east for the North China Craton (NCC) and the Yangtze Craton (YZC). The lithospheric thickness of the eastern NCC is about 80-90 km, and which beneath the Bohai Bay is thinnest, only 60-80 km. For the lower YZC and the Cathaysia block, the lithospheric thickness is about 70-80 km, slightly thinner than the eastern NCC. The observed thin lithosphere (about 60-80 km) beneath the eastern Northeast China is likely to be associated with the Tanlu fault and the Quaternary Changbaishan and Jingpohu volcano. The lithosphere thickness beneath the Tanlu fault is thin or absent, which possibly be related to the upwelling of the hot asthenosphere, and the fault provides channels. *This work was supported by National Key R&D Plan (Grant No. 2017YFC0601406). KEYWORDS: Ambient noise, Phase-weighted stack, Lithosphere, Shear velocity

Preliminary report on deposit models for sand and gravel in the Cache la Poudre River valley

USGS Publications Warehouse

Langer, W.H.; Lindsey, D.A.

1999-01-01

The stratigraphy, sedimentary features, and physical characteristics of gravel deposits in the Cache la Poudre River valley were studied to establish geologic models for these deposits. Because most of the gravel mined in the valley is beneath the low terraces and floodplain, the quality of these deposits for aggregate was studied in detail at eight sites in a 25.5-mile reach between Fort Collins and Greeley, Colorado. Aggregate quality was determined by field and laboratory measurements on samples collected under a consistent sampling plan. The Broadway terrace is underlain by Pleistocene alluvium and, at some places, by fine-grained wind-blown deposits. The Piney Creek terrace, low terraces, and floodplain are primarily underlain by Holocene alluvium. Pleistocene alluvium may underlie these terraces at isolated locations along the river. Gravels beneath the Piney Creek terrace, low terraces, and floodplain are divisible into two units that are poorly distinguishable at the upstream end of the study area, but are readily distinguishable about 7 miles downstream. Where distinguished, the two gravel units are separated by a sharp, locally erosional, contact. The upper gravel is probably of Holocene age, but the lower gravel is considered to be Holocene and Pleistocene. The primary variation in particle size of the gravels beneath the floodplain and low terraces of the Cache la Poudre River valley is the downstream decrease in the proportion of particles measuring 3/4 inch and larger. Above Fort Collins, about 60 pct of the gravel collects on the 3/4 inch sieve, whereas about 50 pct of gravel collects on the same sieve size at Greeley. For 1.5-inch sieves, the corresponding values are about 50 pct for Fort Collins and only about 30 pct for Greeley. Local differences in particle size and sorting between the upper and lower gravel units were observed in the field, but only the coarsest particle sizes appear to have been concentrated in the lower unit. Field measurements of aggregate quality, pebble lithology, and shape show little significant downstream variation. Pebble lithology is about 25 percent granite; 48 percent pegmatite; 5-7 percent each of gneiss, quartz, and quartzite; and minor amounts of diabase, schist, volcanic porphyry, and sandstone. Among the rock types, only the volcanic porphyries might be reactive with Portland cement. Pebble shape is dominantly equidimensional with a tendency to form thick, disc-shaped particles. Disc-shaped and spherical particles comprise about 39 percent and 31 percent of the pebble-size fraction, respectively. Rod and blade shapes comprise about 18 and 12 percent of the pebble-size fraction, respectively. The relatively large proportion of equidimensional particles in the Cache la Poudre may be due to the small proportion of layered gneiss in gravel. Pebbles having axial ratios less than 0.5, which might be structurally weak, are rare. The two gravel units show subtle local differences and evidence for derivation of the younger gravel from the older gravel. At many sites, the upper gravel unit tends to contain more quartz plus quartzite, has poorer physical quality, and contains more angular pebbles than the lower gravel. Weathering, followed by transport in the river, might be expected to concentrate quartz and quartzite, degrade physical quality, and break pebbles into angular fragments. This conclusion is consistent with local evidence of an erosional contact between the two gravel units.

Redshifted and blueshifted photoluminescence emission of InAs/InP quantum dots upon amorphization of phase change material.

PubMed

Humam, Nurrul Syafawati Binti; Sato, Yu; Takahashi, Motoki; Kanazawa, Shohei; Tsumori, Nobuhiro; Regreny, Philippe; Gendry, Michel; Saiki, Toshiharu

2014-06-16

We present the mechanisms underlying the redshifted and blueshifted photoluminescence (PL) of quantum dots (QDs) upon amorphization of phase change material (PCM). We calculated the stress and energy shift distribution induced by volume expansion using finite element method. Simulation result reveals that redshift is obtained beneath the flat part of amorphous mark, while blueshift is obtained beneath the edge region of amorphous mark. Simulation result is accompanied by two experimental studies; two-dimensional PL intensity mapping of InAs/InP QD sample deposited by a layer of PCM, and an analysis on the relationship between PL intensity ratio and energy shift were performed.

Groundwater and Leachate Monitoring and Sampling at ERDF, CY 2009

DOE Office of Scientific and Technical Information (OSTI.GOV)

R.L. Weiss, B.L. Lawrence, D.W. Woolery

2010-07-08

This document reports the findings of the groundwater and leachate monitoring and sampling at the Environmental restoration Disposal Facility for calendar year 2009. The purpose of this annual monitoring report is to evaluate the conditions of and identify trends for groundwater beneath the ERDF and report leachate results in fulfillment of the requirements specified in the ERDF ROD and the ERDF Amended ROD.

Groundwater and Leachate Monitoring and Sampling at ERDF, CY 2008

DOE Office of Scientific and Technical Information (OSTI.GOV)

R. L. Weiss; D. W. Woolery

2009-09-03

The purpose of this annual monitoring report is to evaluate the conditions of and identify trends for groundwater beneath the ERDF, to report leachate results in fulfillment of the requirements specified in the ERDF ROD and the ERDF Amended ROD.

Rock pushing and sampling under rocks on Mars

USGS Publications Warehouse

Moore, H.J.; Liebes, S.; Crouch, D.S.; Clark, L.V.

1978-01-01

Viking Lander 2 acquired samples on Mars from beneath two rocks, where living organisms and organic molecules would be protected from ultraviolet radiation. Selection of rocks to be moved was based on scientific and engineering considerations, including rock size, rock shape, burial depth, and location in a sample field. Rock locations and topography were established using the computerized interactive video-stereophotogrammetric system and plotted on vertical profiles and in plan view. Sampler commands were developed and tested on Earth using a full-size lander and surface mock-up. The use of power by the sampler motor correlates with rock movements, which were by plowing, skidding, and rolling. Provenance of the samples was determined by measurements and interpretation of pictures and positions of the sampler arm. Analytical results demonstrate that the samples were, in fact, from beneath the rocks. Results from the Gas Chromatograph-Mass Spectrometer of the Molecular Analysis experiment and the Gas Exchange instrument of the Biology experiment indicate that more adsorbed(?) water occurs in samples under rocks than in samples exposed to the sun. This is consistent with terrestrial arid environments, where more moisture occurs in near-surface soil un- der rocks than in surrounding soil because the net heat flow is toward the soil beneath the rock and the rock cap inhibits evaporation. Inorganic analyses show that samples of soil from under the rocks have significantly less iron than soil exposed to the sun. The scientific significance of analyses of samples under the rocks is only partly evaluated, but some facts are clear. Detectable quantities of martian organic molecules were not found in the sample from under a rock by the Molecular Analysis experiment. The Biology experiments did not find definitive evidence for Earth-like living organisms in their sample. Significant amounts of adsorbed water may be present in the martian regolith. The response of the soil from under a rock to the aqueous nutrient in the Gas Exchange instrument indicates that adsorbed water and hydrates play an important role in the oxidation potential of the soil. The rock surfaces are strong, because they did not scratch, chip or spall when the sampler pushed them. Fresh surfaces of soil and the undersides of rocks were exposed so that they could be imaged in color. A ledge of soil adhered to one rock that tilted, showing that a crust forms near the surface of Mars. The reason for low amounts of iron in the sampIes from under the rocks is not known at this time.

Corrective Action Investigation Plan for Corrective Action Unit 428: Area 3 Septic Waste Systems 1 and 5, Tonopah Test Range, Nevada, REVISION 0, march 1999

DOE Office of Scientific and Technical Information (OSTI.GOV)

DOE /NV

1999-03-26

The Corrective Action Investigation Plan for Corrective Action Unit 428, Area 3 Septic Waste Systems 1 and 5, has been developed in accordance with the Federal Facility Agreement and Consent Order that was agreed to by the U. S. Department of Energy, Nevada Operations Office; the State of Nevada Division of Environmental Protection; and the U. S. Department of Defense. Corrective Action Unit 428 consists of Corrective Action Sites 03- 05- 002- SW01 and 03- 05- 002- SW05, respectively known as Area 3 Septic Waste System 1 and Septic Waste System 5. This Corrective Action Investigation Plan is used inmore » combination with the Work Plan for Leachfield Corrective Action Units: Nevada Test Site and Tonopah Test Range, Nevada , Rev. 1 (DOE/ NV, 1998c). The Leachfield Work Plan was developed to streamline investigations at leachfield Corrective Action Units by incorporating management, technical, quality assurance, health and safety, public involvement, field sampling, and waste management information common to a set of Corrective Action Units with similar site histories and characteristics into a single document that can be referenced. This Corrective Action Investigation Plan provides investigative details specific to Corrective Action Unit 428. A system of leachfields and associated collection systems was used for wastewater disposal at Area 3 of the Tonopah Test Range until a consolidated sewer system was installed in 1990 to replace the discrete septic waste systems. Operations within various buildings at Area 3 generated sanitary and industrial wastewaters potentially contaminated with contaminants of potential concern and disposed of in septic tanks and leachfields. Corrective Action Unit 428 is composed of two leachfield systems in the northern portion of Area 3. Based on site history collected to support the Data Quality Objectives process, contaminants of potential concern for the site include oil/ diesel range total petroleum hydrocarbons, and Resource Conservation and Recovery Act characteristic volatile organic compounds, semivolatile organic compounds, and metals. A limited number of samples will be analyzed for gamma- emitting radionuclides and isotopic uranium from four of the septic tanks and if radiological field screening levels are exceeded. Additional samples will be analyzed for geotechnical and hydrological properties and a bioassessment may be performed. The technical approach for investigating this Corrective Action Unit consists of the following activities: (1) Perform video surveys of the discharge and outfall lines. (2) Collect samples of material in the septic tanks. (3) Conduct exploratory trenching to locate and inspect subsurface components. (4) Collect subsurface soil samples in areas of the collection system including the septic tanks and outfall end of distribution boxes. (5) Collect subsurface soil samples underlying the leachfield distribution pipes via trenching. (6) Collect surface and near- surface samples near potential locations of the Acid Sewer Outfall if Septic Waste System 5 Leachfield cannot be located. (7) Field screen samples for volatile organic compounds, total petroleum hydrocarbons, and radiological activity. (8) Drill boreholes and collect subsurface soil samples if required. (9) Analyze samples for total volatile organic compounds, total semivolatile organic compounds, total Resource Conservation and Recovery Act metals, and total petroleum hydrocarbons (oil/ diesel range organics). Limited number of samples will be analyzed for gamma- emitting radionuclides and isotopic uranium from particular septic tanks and if radiological field screening levels are exceeded. (10) Collect samples from native soils beneath the distribution system and analyze for geotechnical/ hydrologic parameters. (11) Collect and analyze bioassessment samples at the discretion of the Site Supervisor if total petroleum hydrocarbons exceed field- screening levels.« less

Detection of a Sharp Structural Boundary in Lowermost Mantle Beneath Alaska by Core Phase PKPbc-df Differential Travel Times - Observation from the Anomalous South Sandwich Islands to Alaska Path

NASA Astrophysics Data System (ADS)

Xin, L.; Kawakatsu, H.; Takeuchi, N.

2017-12-01

Differential travel time residuals of PKPbc and PKPdf for the path from South Sandwich Islands (SSI) to Alaska are usually used to constrain anisotropy of the western hemisphere of the Earth's inner-core. For this polar path, it has been found that PKPbc-df differential residuals are generally anomalously larger than data that sample other regions, and also show strong lateral variation. Due to sparse distribution of seismic stations in Alaska in early times, previous researches have been unable to propose a good model to explain this particular data set. Using data recorded by the current dense stations in Alaska for SSI earthquakes, we reexamine the anomalous behavior of core phase PKPbc-df differential travel times and try to explain the origin. The data sample the inner-core for the polar paths, as well as the lowermost mantle beneath Alaska. Our major observations are: (1) fractional travel time residuals of PKPbc-df increase rapidly within 2° (up to 1%). (2) A clear shift of the residual pattern could be seen for earthquakes with different locations. (3) The residual shows systematic lateral variation: at northern part, no steep increase of residual can be seen. A sharp lateral structural boundary with a P-wave velocity contrast of about 3% at lowermost mantle beneath East Alaska is invoked to explain the steep increase of the observed residuals. By combining the effects of a uniformly anisotropic inner-core and the heterogeneity, the observed residual patterns could be well reproduced. This high velocity anomaly might be related with an ancient subducted slab. Lateral variation of the PKPbc-df residuals suggests that the heterogeneity layer is not laterally continuous and may terminate beneath Northeastern Alaska. We also conclude that core phases may be strongly affected by heterogeneities at lowermost mantle, and should be carefully treated if they are used to infer the inner-core structure.

Behavior and Fate of PFOA and PFOS in Sandy Aquifer Sediment (journal)

EPA Science Inventory

Microcosms were constructed with sediment from beneath a landfill that received waste containing PFOA (perfluorooctanoic acid) and PFOS (perfluorooctane sulfonate). The microcosms were amended with PFOA and PFOS, and sampled after 91, 210, 343, 463, 574, and 740 days of incubat...

Implications for future activity of Grímsvötn volcano, Iceland, from compositional time series of historical tephra

NASA Astrophysics Data System (ADS)

Carpentier, Marion; Sigmarsson, Olgeir; Larsen, Gudrun

2014-05-01

The nature of future eruptions of active volcanoes is hard to predict. Improved understanding of the past volcanic activity is probably the best way to infer future eruptive scenarios. The most active volcano in Iceland, Grímsvötn, last erupted in 2011 with consequences for habitants living close to the volcano and aviation in the North-Atlantic. In an effort to better understand the magmatic system of the volcano, we have investigated the compositions of 23 selected tephra layers representing the last 8 centuries of volcanic activity at Grímsvötn. The tephra was collected in the ablation area of outlet glaciers from Vatnajökull ice cap. The ice-conserved tephra are less prone to alteration than those exposed in soil sections. Major element analyses are indistinguishable and of quartz-normative tholeiite composition, and Sr and Nd isotope ratios are constant. In contrast, both trace element concentrations (Th range from 0.875 ppm to 1.37 ppm and Ni from 28.5 ppm to 56.6 ppm) in the basalts and Pb isotopes show small but significant variations. The high-precision analyses of Pb isotope ratios allow the identification of tephra samples (3 in total) with more radiogenic ratios than the bulk of the samples. The tephra of constant isotope ratios show linear increase in incompatible element concentrations with time. The rate of increasing concentrations permits exploring possible future scenarios assuming that the magmatic system beneath the volcano follows the established historical evolution. Assuming similar future behaviour of the magma system beneath Grímsvötn volcano, the linear increase in e.g. Th concentration suggests that the volcano is likely to principally produce basalts for the next 500-1000 years. Evolution of water concentration will most likely follow those of incompatible elements with consequent increases in explosiveness of future Grímsvötn eruptions.

Constraining the crustal root geometry beneath Northern Morocco

NASA Astrophysics Data System (ADS)

Díaz, J.; Gil, A.; Carbonell, R.; Gallart, J.; Harnafi, M.

2016-10-01

Consistent constraints of an over-thickened crust beneath the Rif Cordillera (N. Morocco) are inferred from analyses of recently acquired seismic datasets including controlled source wide-angle reflections and receiver functions from teleseismic events. Offline arrivals of Moho-reflected phases recorded in RIFSIS project provide estimations of the crustal thicknesses in 3D. Additional constraints on the onshore-offshore transition are inferred from shots in a coeval experiment in the Alboran Sea recorded at land stations in northern Morocco. A regional crustal thickness map is computed from all these results. In parallel, we use natural seismicity data collected throughout TopoIberia and PICASSO experiments, and from a new RIFSIS deployment, to obtain receiver functions and explore the crustal thickness variations with a H-κ grid-search approach. This larger dataset provides better resolution constraints and reveals a number of abrupt crustal changes. A gridded surface is built up by interpolating the Moho depths inferred for each seismic station, then compared with the map from controlled source experiments. A remarkably consistent image is observed in both maps, derived from completely independent data and methods. Both approaches document a large crustal root, exceeding 50 km depth in the central part of the Rif, in contrast with the rather small topographic elevations. This large crustal thickness, consistent with the available Bouguer anomaly data, favors models proposing that the high velocity slab imaged by seismic tomography beneath the Alboran Sea is still attached to the lithosphere beneath the Rif, hence pulling down the lithosphere and thickening the crust. The thickened area corresponds to a quiet seismic zone located between the western Morocco arcuate seismic zone, the deep seismicity area beneath western Alboran Sea and the superficial seismicity in Alhoceima area. Therefore, the presence of a crustal root seems to play also a major role in the seismicity distribution in northern Morocco.

The antibody-based magnetic microparticle immunoassay using p-FET sensing platform for Alzheimer's disease pathogenic factor

NASA Astrophysics Data System (ADS)

Kim, Chang-Beom; Kim, Kwan-Soo; Song, Ki-Bong

2013-05-01

The importance of early Alzheimer's disease (AD) detection has been recognized to diagnose people at high risk of AD. The existence of intra/extracellular beta-amyloid (Aβ) of brain neurons has been regarded as the most archetypal hallmark of AD. The existing computed-image-based neuroimaging tools have limitations on accurate quantification of nanoscale Aβ peptides due to optical diffraction during imaging processes. Therefore, we propose a new method that is capable of evaluating a small amount of Aβ peptides by using photo-sensitive field-effect transistor (p-FET) integrated with magnetic force-based microbead collecting platform and selenium(Se) layer (thickness ~700 nm) as an optical filter. This method demonstrates a facile approach for the analysis of Aβ quantification using magnetic force and magnetic silica microparticles (diameter 0.2~0.3 μm). The microbead collecting platform mainly consists of the p-FET sensing array and the magnet (diameter ~1 mm) which are placed beneath each sensing region of the p-FET, which enables the assembly of the Aβ antibody conjugated microbeads, captures the Aβ peptides from samples, measures the photocurrents generated by the Q-dot tagged with Aβ peptides, and consequently results in the effective Aβ quantification.

Vertical Mixing in the Dead Sea

NASA Astrophysics Data System (ADS)

Gertman, Isaac; Ozer, Tal; Katsenelson, Boris; Lensky, Nadav

2015-04-01

For hundreds of years, the Dead Sea was characterized by a stable haline stratification, supported by runoff. The penetration of the winter convection was limited to an upper mixed layer (UML) of about 30-50 m. Below the UML, a stable halocline prevented the mixing. As a result of the runoff reduction, the UML salinity increased and the gravitational stability diminished. During the winter of 1978-1979, the sea water overturned, ending the long-term stable hydrological regime. Since 1979, the haline stratification structure reoccurred twice after extremely rainy winters, in 1980-82 and 1992-1995. In other years, the sea was entirely mixed by winter thermal convection ( which occurs from November to March ) and had a seasonal pycnocline beneath the UML during summer. Profiles of temperature and quasi-salinity (density anomaly from 1000 kg/m3 for the chosen reference temperature of 32° C) during the last 19 years, show the formation of summer ``overturning halocline'' beneath the UML, and the thermocline that supports the stable stratification. Another warm and saline layer is formed also during the summer period near the bottom. This layer spreads from the southern part of the sea, where end-brine is discharged to the sea from the Israeli and Jordanian salt plants' evaporation ponds. The end-brine has extremely high salinity (˜ 350 g/kg) and, in spite of the high temperatures ( ˜ 45° C), high density (1350 kg/m^3), it therefore spreads as a gravitational current in the Dead Sea deep basin. Estimation of the density ratio (Rρ) for the Dead Sea water (where measurements of water salinity is quite difficult) was done using quasi-salinity (σ32) and potential temperature (θ): Rρ= [α(partialθ/partial z)]/[β(partial σ32/partial z)], where α and β are temperature expansion and quasi-salinity contraction coefficients respectively. The values of α and β for the Dead Sea water were defined from water samples collected during 2008. The Rρ values confirm that the summer Dead Sea thermohaline structure is appropriate for double diffusion mixing. A salt fingers regime beneath the UML (1.3< Rρ

New constraints on the textural and geochemical evolution of the upper mantle beneath the Styrian basin

NASA Astrophysics Data System (ADS)

Aradi, Laszlo; Hidas, Károly; Zanetti, Alberto; János Kovács, István; Patkó, Levente; Szabó, Csaba

2016-04-01

Plio-Pleistocene alkali basaltic volcanism sampled sporadically the upper mantle beneath the Carpathian-Pannonian Region (CPR, e.g. [1]). Lavas and pyroclasts often contain mantle derived xenoliths, and the majority of them have been extensively studied [1], except the westernmost Styrian Basin Volcanic Field (SBVF, Eastern Austria and Slovenia). In the SBVF only a few volcanic centers have been studied in details (e.g. Kapfenstein & Tobaj). Based on these studies, the upper mantle beneath the SBVF is consists of dominantly high temperature, texturally and geochemically homogeneous protogranular spinel lherzolite. New major and trace element data from rock-forming minerals of ultramafic xenoliths, coupled with texture and deformation analysis from 12 volcanic outcrops across the SBVF, suggest that the lithospheric roots of the region are more heterogeneous than described previously. The studied xenoliths are predominantly lherzolite, amphibole is a common phase that replaces pyroxenes and spinels and proves modal metasomatism. Phlogopite coupled with apatite is also present in amphibole-rich samples. The texture of the xenoliths is usually coarse-grained and annealed with low abundance of subgrain boundaries in both olivine and pyroxenes. Olivine crystal preferred orientation (CPO) varies between the three most abundant one: [010]-fiber, orthogonal and [100]-fiber symmetry [2]. The CPO of pyroxenes is usually coherent with coeval deformation with olivine, however the CPO of amphibole is suggesting postkinematic epitaxial overgrowth on the precursor pyroxenes. According to equilibrium temperatures, the studied xenolith suite samples a broader temperature range (850-1100 °C) than the literature data, corresponding to mantle depths between 30 and 60 km, which indicates that the xenolith suite only represents the shallower part of the recent 100 km thick lithospheric mantle beneath the SBVF. The equilibrium temperatures show correlation with the varying CPO symmetries, with [100]-fiber and orthorhombic symmetry appear in the high temperature (>1000 °C) xenoliths, which are thought to have an asthenospheric origin [3]. Based on our study, the subcontinental lithospheric mantle beneath the western part of the CPR is not as homogeneous as it was reported before. The shallower part of the mantle lithosphere contains peridotites, where the pervasive deformation and subsequent thermal recovery of the upper mantle was followed by melt percolation events causing extensive metasomatism. This research was granted by the Hungarian Science Foundation (OTKA, 78425 to Cs. Szabó). K. Hidas' research leading to these results was funded by the European Union Framework Programme 7 (EU-FP7) Marie Curie postdoctoral grant PIEF-GA-2012- 327226. References: [1]Szabó, C. et al. 2004. Tectonophysics, 393(1), 119-137. [2] Tommasi, A., Vauchez, A. 2015. Tectonophysics, 661, 11-37. [3] Kovács, I. et al. 2012. Tectonophysics, 514, 168-179.

S-N profile of Receive function image across Qiangtang, Northern Tibet

NASA Astrophysics Data System (ADS)

He, R.; Gao, R.; Deng, G.; Li, W.; Hou, H.; Lu, Z.; Xiong, X.

2010-12-01

Huge thicken Triassic and Jurassic sediments widely outcorp within Qiangtang, tens of oilstones outcorped within Qiangtang showed that Qiangtang have a good advantage in exploring oil and gas. So, the basement beneath Qiangtang and its structures have become the key for us to look for oil and gas accumulations. Within tectonic settings of Qiangtang, the center uplift of Qiangtang (abbr. CUQT) and its developments have become the great barrier to understand the basement and its structures within the basin. Because of complicated structure relief and blueschist and ophiolite outcorps within the CUQT, there was the paradox for lots of geologist to understand how the CUQT developed. One was that it formed under the extension environment. On the contrary, CUQT was ever paleo-Tethys suture zone, because CUQT had the belt of blueschists and ophiolite. So, different opinions to CUQT resulted in the different viewpoints in the basin beneath Qiangtang terrane. Surveying deep structure beneath the CUQT was the key to understand the basement under Qiangtang. In past two years, we have deployed 40 portable broadband seismic stations along E88°to across the whole Qiangtang from Bangong-Nujiang Suture, southern side of Qiangtang terrane, to northern margin of Qiangtang terrane. The temporary network collected a lot of farm waveform data, which is helpful to know about the more finest deep structure beneath the CUQT and its two sides basin. We used P-to-S receiver functions methods to get deep structure image beneath the profile. The preliminary results showed: (1) Within the crust, the velocity structure beneath southern Qiangtang basin is higher than beneath northern Qiangtang basin. (2) Sedimental layer within southern Qiangtang basin is thichen than within northern Qiangtang basin. Combined with other geophysical information, CUQT is an important lithosphere-level boundary fault belts, and southern Qiangtang basin have great difference with northern Qiangtang basin, in velocity structure, basement depth, although during Qiangtang terrane had been strongly reconstructed laterly, especiall in Cenozoic uplift of the Tibetan plateau. The above-mentioned evidences showed that Qiangtang terrance in present-day tectonic study should be divided by CUQT into two parts which includes south Qiangtang terrane in sourthern side and north Qiangtang terrrane in northern side. Because CUQT and Qiangtang terrane were traditionally named, tectonic settings within the Tibetan plateau had to be remarked renewedly . This project was financially supported together by Natural Science Foundations of China (40774051, 40974060), the basic outlay of scientific research work from Ministry of Science and Technology, China in 2009 ( J0915 ), China National Probing Project (SinoProbe-02).

Magnetotelluric Imaging of Lower Crustal Melt and Lithospheric Hydration in the Rocky Mountain Front Transition Zone, Colorado, USA

NASA Astrophysics Data System (ADS)

Feucht, D. W.; Sheehan, A. F.; Bedrosian, P. A.

2017-12-01

We present an electrical resistivity model of the crust and upper mantle from two-dimensional (2-D) anisotropic inversion of magnetotelluric data collected along a 450 km transect of the Rio Grande rift, southern Rocky Mountains, and High Plains in Colorado, USA. Our model provides a window into the modern-day lithosphere beneath the Rocky Mountain Front to depths in excess of 150 km. Two key features of the 2-D resistivity model are (1) a broad zone ( 200 km wide) of enhanced electrical conductivity (<20 Ωm) in the midcrust to lower crust that is centered beneath the highest elevations of the southern Rocky Mountains and (2) hydrated lithospheric mantle beneath the Great Plains with water content in excess of 100 ppm. We interpret the high conductivity region of the lower crust as a zone of partially molten basalt and associated deep-crustal fluids that is the result of recent (less than 10 Ma) tectonic activity in the region. The recent supply of volatiles and/or heat to the base of the crust in the late Cenozoic implies that modern-day tectonic activity in the western United States extends to at least the western margin of the Great Plains. The transition from conductive to resistive upper mantle is caused by a gradient in lithospheric modification, likely including hydration of nominally anhydrous minerals, with maximum hydration occurring beneath the Rocky Mountain Front. This lithospheric "hydration front" has implications for the tectonic evolution of the continental interior and the mechanisms by which water infiltrates the lithosphere.

Prey of nesting ospreys on the Willamette and Columbia Rivers, Oregon and Washington

USGS Publications Warehouse

Johnson, B.L.; Kaiser, J.L.; Henny, C.J.; Grove, R.A.

2008-01-01

To more effectively use ospreys as a biomonitoring tool and to better assess contaminant pathways, the diet of nesting ospreys (Pandion haliaetus) was studied along the lower Columbia and upper mainstem Willamette rivers by evaluating prey remains collected from wire baskets constructed under artificial feeding perches installed near nest sites and from the ground beneath natural feeding perches and nests. Prey remains from 1997-2004 on the Columbia River and 1993 (previously published) and 2001 on the Willamette River were evaluated and compared. Largescale suckers (Catostomus macrocheilus) were the predominate fish species identified in collections from the Columbia River (61.5% [84.3% biomass]) and Willamette River (76.0% [92.7% biomass]). Prey fish diversity, when based only on ground collections, was higher in the Columbia (2.45) than the Willamette river (1.92) (P = 0.038). Prey fish diversity in collections from the Willamette River did not differ between this study (2001) and previous study (1993) (P = 0.62). Fishbones recovered in wire baskets are likely more representative of osprey diet compared to bones recovered from the ground, because prey diversity was higher among basket samples compared to ground collections (wire basket diversity = 5.25 vs. ground collection diversity = 2.45, P = 0.011). Soft-boned salmonids (Oncorhynchus spp.), American shad (Alosa sapidissima), and mountain whitefish (Prosopium williamsoni) were probably underrepresented in collections obtained from the ground. Study results suggest that baskets provide a better method for assessing osprey diet than other indirect methods. These findings augment available osprey food-habits information and provide additional biological and ecological information to better assess potential impacts of various environmental contaminants on nesting ospreys.

The Resource beneath Our Feet

ERIC Educational Resources Information Center

Clary, Renee

2015-01-01

This article describes activities in which students sample, investigate, classify, and compare characteristics (i.e., texture, color, density, porosity) of local soils, evaluating whether the soils are healthy or at risk. Students investigate correlations between geology and geography, predict which soil types may go extinct in their state, and…

PERFORMANCE OF A NEW PASSIVE DIFFUSION SAMPLER FOR SOIL GAS AND GROUND WATER SAMPLING

EPA Science Inventory

Conventional practice to estimate intrusion of fuel vapors from ground water to buildings measures the concentration of BTEX in ground water beneath the building using a conventional well screened across the water table. Conventional practice assumes that the concentration of co...

Buildup Index as an Expression of Moisture Content in Duff

Treesearch

Von J. Johnson

1968-01-01

The relation between Buildup index and moisture content of grouped litter and duff samples from beneath four medium-site forest stands closely approximated the relation between Buildup index and moisture equivalent of 5-day timelag fuels having an equilibrium moisture content of 15 percent

Dieldrin and heptachlor residues in dead gray bats, Franklin County, Missouri--1976 versus 1977

USGS Publications Warehouse

Clark, D.R.; LaVal, R.K.; Krynitsky, A.J.

1980-01-01

Lethal dieldrin concentrations were found in the brains of dead gray bats (Myotis grisescens) collected during 1976 and 1977 beneath a maternity roost in a Missouri cave. In addition, residues of heptachlor epoxide, oxychlordane, cis-chlordane, and trans-nonachlor increased significantly in both brains and carcasses of bats collected during 1977. These increases appear to reflect a switch by local farmers from aldrin, dieldrin's parent compound, to heptachlor for the control of cutworms. They also constitute an additional threat to this colony of this endangered bat species.

Magnetic properties of the upper mantle beneath the continental United States

NASA Astrophysics Data System (ADS)

Friedman, S. A.; Ferre, E. C.; Demory, F.; Rochette, P.; Martin Hernandez, F.; Conder, J. A.

2012-12-01

The interpretation of long wavelength satellite magnetic data (Magsat, Oersted, CHAMP, SWARM) requires an understanding of magnetic mineralogy in the lithospheric mantle and reliable models of induced and remanent magnetic sources in the lithospheric mantle and the crust. Blakely et al. (2005) proposed the hypothesis of a magnetic lithospheric mantle in subduction zones. This prompted us to reexamine magnetic sources in the lithospheric mantle in different tectonic settings where unaltered mantle xenolith have been reported since the 1990s. Xenoliths from the upper mantle beneath the continental United States show different magnetic properties depending on the tectonic setting in which they equilibrated. Three localities in the South Central United States (San Carlos, AZ; Kilbourne Hole, NM; Knippa, TX) produced lherzolite and harzburgite xenoliths, while the Bearpaw Mountains in Montana (subduction zone) produced dunite and phlogopite-rich dunite xenoliths. Paleomagnetic data on these samples shows the lack of secondary alteration which is commonly caused by post-eruption serpentinization and the lack of basalt contamination. The main magnetic carrier is pure magnetite. The ascent of mantle xenoliths to the surface of the Earth generally takes only a few hours. Numerical modelling shows that nucleation of magnetite during ascent would form superparamagnetic grains and therefore cannot explain the observed magnetic grain sizes. This implies that the ferromagnetic phases present in the studied samples formed at mantle depth. The samples from the South Central United States exhibit a small range in low-field magnetic susceptibility (+/- 0.00003 [SI]), and Natural Remanent Magnetization (NRM) between 0.001 - 0.100 A/m. To the contrary samples from the Bearpaw Mountains exhibit a wider range of low-field susceptibilities (0.00001 to 0.0015 [SI]) and NRM (0.01 and 9.00 A/m). These samples have been serpentinized in-situ by metasomatic fluids related to the Farallon plate (Facer et al., 2009). Hence, the magnetic properties of the lithospheric mantle beneath the continental United States differ significantly depending on tectonic setting. The combination of the low geotherm observed in the Bearpaw Mountains with the stronger induced and remanent magnetization of mantle rocks in this area may produce a detectable LWMA.

The release of water from forest snowpacks during winter

Treesearch

Harold F. Haupt

1972-01-01

In the northern Rocky Mountains, in Idaho, data collected during three winters demonstrate why there is always less snow beneath the canopy of a cedar-hemlock forest than in the adjacent small openings. The author presents as evidence the differential release of water, which originates in the canopy as throughfall-drip, thus accounting for part of the deficiency in...

The Nature of the Planning Environment: And the Effects of Guidance, Organization and Authority

DTIC Science & Technology

2013-05-23

home reading the newspaper, and notice a small blurb buried beneath the fold in the back of ... THE NATURE OF THE PLANNING ENVIRONMENT: AND THE EFFECTS OF GUIDANCE, ORGANIZATION AND AUTHORITY A Monograph by Major...0704-0188 Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for

Beneath the Numbers: A Review of Gender Disparities in Undergraduate Education across Science, Technology, Engineering, and Math Disciplines

ERIC Educational Resources Information Center

Eddy, Sarah L.; Brownell, Sara E.

2016-01-01

This focused collection explores inequalities in the experiences of women in physics. Yet, it is important for researchers to also be aware of and draw insights from common patterns in the experiences of women across science, technology, engineering and mathematics (STEM) disciplines. Here, we review studies on gender disparities across college…

It Happened in Antarctica. A Collection of Observations Requiring Scientific Explanations.

ERIC Educational Resources Information Center

Yaxley, Murray

There are many reasons for studying Antarctica. It is the key element in the world's climate. Some of the secrets of the earth's past are locked beneath its icecap. It has a fascinating physical environment and a unique and fragile ecosystem. It is a frontier of scientific research and technological development. Its history is an important and…

Picture This: 4-H Press Corps Builds Life Skills

ERIC Educational Resources Information Center

Clary, Christy D.

2018-01-01

A picture is worth a thousand words! Extension professionals are often looking for the picture that best captures an event and tells its story. Look beneath the surface, though, and a picture is worth much more. Developing a 4-H press corps results in a collection of useful photos but has the added benefit of providing 4-H members with an…

Geographic and stratigraphic distribution of coastal Quaternary aminozones across the Cape Fear Arch, U. S. Atlantic Geology Coastal Plain

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wehmiller, J.F.; York, L.L.; Krantz, D.E.

1992-01-01

The interpretation of the regional aminostratigraphy of Coastal Plain Quaternary units from North and South Carolina is potentially affected by sampling biases, variable preservation of coastal records, reoccupation of coastal environments by multiple transgressions, geochemical alteration of samples, variable thermal histories of specific samples, and intergeneric and interlaboratory differences in analytical results.Two primary models for the correlation of emergent Coastal Plain units diverge significantly in southeastern North Carolina. New data from fresh exposure (1990--1991) at emergent sites between Wilmington, NC and Charleston, SC, from previous onshore collections in this region, and from submergent samples between Cape Lookout, NC and Capemore » Romain, SC provide insight into the nature of these correlation issues. Although sampling of the area is not uniform, these results fill a major gap between regions of previous aminostratigraphy study. Inferred early-to-middle Pleistocene aminozones dominate the emergent coastal region between Cape Lookout and Romain, and late Pleistocene aminozones in this area are represented by subsurface samples beneath barrier islands or in shallow inner shelf cores, but have not been found onshore. A map view of the distribution of aminozones along the coast between northeastern NC and central SC mimics that of pre-Quaternary units that thin or disappear over the axis of the Cape Fear Arch, suggesting that the sampled Quaternary record reflects the combination of processes responsible for the preservation of the pre-Quaternary record. This perspective should provide a model for resolution of various geochronological controversies that have arisen because of limited stratigraphic or geochemical data.« less

Variable Flow Pathways and Geochemical History of Seepage Under Mississippi River Levees: 2011, 2015, and 2016 Floods

NASA Astrophysics Data System (ADS)

Voll, K.; Davidson, G. R.; Borrok, D. M.; Corcoran, M. K.; Kelley, J.; Ma, L.

2017-12-01

Seepage beneath levees during flood stage is a concern when piping occurs, creating channels under the levee and forming sand boils where transported sediments discharge. The flow depth beneath a levee varies with surface geology, following deeper paths where the levee sits on channel fill deposits and shallower paths where it sits on sandbar deposits. Piping along shallow pathways poses an increased risk of levee failure. The Lower Mississippi River Valley alluvial aquifer is geochemically stratified, with reducing waters at greater depth, resulting in unique geochemical signatures for water passing beneath the Mississippi River levee along variable flow paths. Sampling from sand boils and flowing relief wells north of Vicksburg, MS, during the 2011, 2015, and 2016 flood events demonstrates the utility of using the geochemistry of discharge water to identify different flow pathways, and to provide greater insight on the variable water-rock interactions as a function of depth. Relief wells discharge water mainly from deeper zones, reflected by low redox potential, high Fe and As, and low 87Sr/86Sr ratios. High variability in As concentrations may result from varying degrees of reductive dissolution of Fe and Mn and release of co-precipitated As. At shallower depths the aquifer is mostly oxic, lower in Fe, As, and bicarbonate, and higher in sulfate concentrations and 87Sr/86Sr ratios. The geochemical signatures of sand-boil discharge varied between boils that were short distances apart. Water samples plotted on a Piper Diagram fell along two distinct trends starting with river water and diverging along pathways reflecting unique water-rock interaction at different depths. Strontium isotope ratios indicate differences in geochemistry are not just from variable redox reactions, but also reflect dissolution of primary minerals of unique composition or provenance. Oxygen and hydrogen isotopes of all subsurface samples reflect an unexpected level of evaporation of river water prior to recharge to the aquifer, attributed to the presence of numerous water-filled depressions between the river channel and levee system. Tritium levels from wells and boils ranged from 2.3 to 7.4 TU, with some high values coming from deeper zones indicating localized variation in the residence time of water at equal depths beneath levees.

Imaging Ruptured Lithosphere Beneath the Arabian Peninsula Using S-wave Receiver Functions

NASA Astrophysics Data System (ADS)

Hansen, S. E.; Rodgers, A. J.; Schwartz, S. Y.; Al-Amri, A. M.

2006-12-01

The lithospheric thickness beneath the Arabian Peninsula has important implications for understanding the tectonic processes associated with continental rifting along the Red Sea. However, estimates of the lithospheric thickness are limited by the lack of high-resolution seismic observations sampling the lithosphere- asthenosphere boundary (LAB). The S-wave receiver function technique allows point determinations of Moho and LAB depths by identifying S-to-P conversions from these discontinuities beneath individual seismic stations. This method is superior to P-wave receiver functions for identifying the LAB because P-to-S multiple reverberations from shallower discontinuities (such as the Moho) often mask the direct conversion from the LAB while S-to-P boundary conversions arrive earlier than the direct S phase and all multiples arrive later. We interpret crustal and lithospheric structure across the entire Arabian Peninsula from S-wave receiver functions computed at 29 stations from four different seismic networks. Generally, both the Moho and the LAB are shallowest near the Red Sea and become deeper towards the Arabian interior. Near the coast, the Moho increases from about 12 to 35 km, with a few exceptions showing a deeper Moho beneath stations that are situated on higher topography in the Asir Province. The crustal thickening continues until an average depth of about 40-45 km is reached over both the central Arabian Shield and Platform. The LAB near the coast is at a depth of about 50 km, increases rapidly, and reaches an average maximum depth of about 120 km beneath the Arabian Shield. At the Shield-Platform boundary, a distinct step is observed in the lithospheric thickness where the LAB depth increases to about 160 km. This step may reflect remnant lithospheric thickening associated with the Shield's accretion onto the Platform and has an important role in guiding asthenospheric flow beneath the eastern margin of the Red Sea. This work was performed in part under the auspices of the U.S. Department of Energy by University of California, Lawrence Livermore National Laboratory under contract W-7405-Eng-48.

Next generation sensing platforms for extended deployments in large-scale, multidisciplinary, adaptive sampling and observational networks

NASA Astrophysics Data System (ADS)

Cross, J. N.; Meinig, C.; Mordy, C. W.; Lawrence-Slavas, N.; Cokelet, E. D.; Jenkins, R.; Tabisola, H. M.; Stabeno, P. J.

2016-12-01

New autonomous sensors have dramatically increased the resolution and accuracy of oceanographic data collection, enabling rapid sampling over extremely fine scales. Innovative new autonomous platofrms like floats, gliders, drones, and crawling moorings leverage the full potential of these new sensors by extending spatiotemporal reach across varied environments. During 2015 and 2016, The Innovative Technology for Arctic Exploration Program at the Pacific Marine Environmental Laboratory tested several new types of fully autonomous platforms with increased speed, durability, and power and payload capacity designed to deliver cutting-edge ecosystem assessment sensors to remote or inaccessible environments. The Expendable Ice-Tracking (EXIT) gloat developed by the NOAA Pacific Marine Environmental Laboratory (PMEL) is moored near bottom during the ice-free season and released on an autonomous timer beneath the ice during the following winter. The float collects a rapid profile during ascent, and continues to collect critical, poorly-accessible under-ice data until melt, when data is transmitted via satellite. The autonomous Oculus sub-surface glider developed by the University of Washington and PMEL has a large power and payload capacity and an enhanced buoyancy engine. This 'coastal truck' is designed for the rapid water column ascent required by optical imaging systems. The Saildrone is a solar and wind powered ocean unmanned surface vessel (USV) developed by Saildrone, Inc. in partnership with PMEL. This large-payload (200 lbs), fast (1-7 kts), durable (46 kts winds) platform was equipped with 15 sensors designed for ecosystem assessment during 2016, including passive and active acoustic systems specially redesigned for autonomous vehicle deployments. The senors deployed on these platforms achieved rigorous accuracy and precision standards. These innovative platforms provide new sampling capabilities and cost efficiencies in high-resolution sensor deployment, including reconnaissance for annual fisheries and marine mammal surveys; better linkages between sustained observing platforms; and adaptive deployments that can easily target anomalies as they arise.

Geochemistry and stratigraphic correlation of basalt lavas beneath the Idaho Chemical Processing Plant, Idaho National Engineering Laboratory

USGS Publications Warehouse

Reed, M.F.; Bartholomay, R.C.; Hughes, S.S.

1997-01-01

Thirty-nine samples of basaltic core were collected from wells 121 and 123, located approximately 1.8 km apart north and south of the Idaho Chemical Processing Plant at the Idaho National Engineering Laboratory. Samples were collected from depths ranging from 15 to 221 m below land surface for the purpose of establishing stratigraphic correlations between these two wells. Elemental analyses indicate that the basalts consist of three principal chemical types. Two of these types are each represented by a single basalt flow in each well. The third chemical type is represented by many basalt flows and includes a broad range of chemical compositions that is distinguished from the other two types. Basalt flows within the third type were identified by hierarchical K-cluster analysis of 14 representative elements: Fe, Ca, K, Na, Sc, Co, La, Ce, Sm, Eu, Yb, Hf, Ta, and Th. Cluster analyses indicate correlations of basalt flows between wells 121 and 123 at depths of approximately 38-40 m, 125-128 m, 131-137 m, 149-158 m, and 183-198 m. Probable correlations also are indicated for at least seven other depth intervals. Basalt flows in several depth intervals do not correlate on the basis of chemical compositions, thus reflecting possible flow margins in the sequence between the wells. Multi-element chemical data provide a useful method for determining stratigraphic correlations of basalt in the upper 1-2 km of the eastern Snake River Plain.

Vitex agnus-castus is a preferred host plant for Hyalesthes obsoletus.

PubMed

Sharon, Rakefet; Soroker, Victoria; Wesley, S Daniel; Zahavi, Tirtza; Harari, Ally; Weintraub, Phyllis G

2005-05-01

Hyalesthes obsoletus Signoret (Homoptera: Cixiidae) is a polyphagous planthopper that transmits stolbur phytoplasma (a causative agent of "yellows" disease) to various weeds, members of the Solanaceae, and wine grapes (Vitis vinifera L.) in Europe and the Middle East. Planthoppers were collected by hand vacuuming eight native plant species. Vitex agnus-castus L., a shrub in the Verbenaceae, hosted the largest number of H. obsoletus, although Olea europaea L. also served as a host for adults. Using a Y-olfactometer, we compared the planthoppers relative preference for V. agnus-castus, Convolvulus arvensis, and V. vinifera. V. agnus-castus was more attractive to both male and female H. obsoletus than the other plants. H. obsoletus antennal response was stronger to volatiles collected from V. agnuscastus than from Cabernet Sauvignon variety of V. vinifera. To determine if V. agnus-castus would serve as a reservoir for the pathogen, H. obsoletus were collected from leaf and stem samples of native V. agnus-castus, and were tested by polymerase chain reaction (PCR) for the presence of phytoplasma DNA. While 14% and 25% (2003 and 2004, respectively) of the insects tested positive for phytoplasma DNA, none of the plant samples tested positive. To determine if V. agnus-castus could serve as a host plant for the development of the planthopper, we placed emergence cages beneath field shrubs and enclosed wild-caught H. obsoletus in a cage with a potted young shrub. We found adult H. obsoletus in the emergence cases and planthopper nymphs in the soil of the potted plant. We concluded that V. agnus-castus is attractive to H. obsoletus, which seems to be refractory to phytoplasma infections and warrants further testing as a trap plant near vineyards.

Groundwater and Leachate Monitoring and Sampling at ERDF, CY 2007

DOE Office of Scientific and Technical Information (OSTI.GOV)

R. L. Weiss; T. A. Lee

2008-06-25

The purpose of this annual monitoring report is to evaluate the conditions of and identify trends for groundwater beneath the Environmental Restoration Disposal Facility and to report leachate results in fulfillment of the requirements specified in the ERDF Record of Decision and the ERDF Amended Record of Decision.

Passive PE Sampling in Support of In Situ Remediation of Contaminated Sediments: Standard Operating Procedure for PED Deployment

DTIC Science & Technology

2012-12-01

mineral and organic materials situated beneath an aqueous layer. PEDs assembled, installed, and retrieved following these procedures will be suitable...at a minimum, wearing adequate protective equipment, flotation devices, and making use of lifelines. 8.0 References Massachusetts Institute of

SEDIMENT AND PLANT PHOSPHORUS IN TWO THALASSIA TESTUDINUM SEAGRASS BEDS OF SANTA ROSA SOUND, NW FLORIDA

EPA Science Inventory

We investigated phosphorus concentrations in the seagrass, Thalassia testudinum, and the supporting quartz sediments of two meadows in Santa Rosa Sound. One meadow was sampled during 2002, and the other during 2003. Triplicate sediment and biomass cores were obtained from beneath...

Heavy metals in bark of Pinus massoniana (Lamb.) as an indicator of atmospheric deposition near a smeltery at Qujiang, China.

PubMed

Kuang, Yuan Wen; Zhou, Guo Yi; Da Wen, Zhi; Liu, Shi Zhong

2007-06-01

Rapid urbanization and the expansion of industrial activities in the past several decades have led to large increases in emissions of pollutants in the Pearl River Delta of south China. Recent reports have suggested that industrial emission is a major factor contributing to the damages in current natural ecosystem in the Delta area. Tree barks have been used successfully to monitor the levels of atmospheric metal deposition in many areas, but rarely in China. This study aimed at determining whether atmospheric heavy metal deposition from a Pb-Zn smeltery at Qujiang, Guangdong province, could be accurately reflected both in the inner bark and the outer bark of Masson pine (Pinus massoniana L.). The impact of the emission from smeltery on the soils beneath the trees and the relationships of the concentrations between the soils and the barks were also analyzed. Barks around the bole of Pinus massoniana from a pine forest near a Pb-Zn smeltery at Qujiang and a reference forest at Dinghushan natural reserve were sampled with a stainless knife at an average height of 1.5 m above the ground. Mosses and lichens on the surface barks were cleaned prior to sampling. The samples were carefully divided into the inner bark (living part) and the outer bark (dead part) in the laboratory, and dried and ground, respectively. After being dry-ashed, the powder of the barks was dissolved in HNO3. The solutions were analyzed for iron (Fe), manganese (Mn), copper (Cu), zinc (Zn), chromium (Cr), nickel (Ni) and cobalt (Co) by inductively coupled plasmas emission spectrometry (ICP, PS-1000AT, USA) and Cadmium (Cd) and lead (Pb) by graphite furnace atomic absorption spectrometry (GFAAS, ZEENIT 60, Germany). Surface soils (0-10 cm) beneath the sample trees were also collected and analyzed for the selected metals. Concentrations of the selected metals in soils at Qujiang were far above their environmental background values in the area, except for Fe and Mn, whilst at Dinghushan, they were far below their background values, except for Cd and Co. Levels of the metals, in particular Pb and Zn, in the soils beneath the sample trees at Qujiang were higher than those at Dinghushan with statistical significance. The result suggested that the pine forest soils at Qujiang had a great input of heavy metals from wet and dry atmospheric deposition, with the Pb-Zn smeltery most probably being the source. Levels of Cu, Fe, Mn, Zn, Ni and Pb at Qujiang, both in the inner and the outer bark, were statistically higher than those at Dinghushan. Higher concentrations of Pb, Fe, Zn and Cu may come from the stem-flow of elements leached from the canopy, soil splash on the 1.5 m height and sorption of metals in the mosses and lichens growing on the bark, which were direct or indirect results from the atmospheric deposition. Levels of heavy metals in the outer barks were associated well with the metal concentrations in the soil, reflecting the close relationships between the metal atmospheric deposition and their accumulation in the outer bark of Masson pine. The significant (p<0.01) correlations of Fe-Cu, Fe-Cr, Fe-Pb, Fe-Ni, Pb-Ni, and Pb-Zn in the outer barks at Qujiang again suggested a common source for the metals. The correlation only occurred between Pb and Ni, Cd and Co in the outer barks at Dinghushan, which suggested that those metals must possibly have other uncommon sources. Atmospheric deposition of the selected metals was great at Qujiang, based on the levels in the bark of Pinus massoniana and on the concentrations in the soils beneath the trees compared with that at Dinghushan. Bark of Pinus massoniana, especially the outer bark, was an indicator of metal loading at least at the time of sampling. The results from this study and the techniques employed constituted a new contribution to the development of biogeochemical methods for environmental monitoring particularly in areas with high frequency of pollution in China. The method would be of value for follow up studies aimed at the assessment of industrial pollution in other areas similar with the Pearl River Delta.

Environmental Impact Assessment of Dumpsite: Case Study from southwestern Saudi Arabia

NASA Astrophysics Data System (ADS)

Alfaifi, H. J.; Alhumidan, S. M.; Kahal, A. Y.; Abdel Rahman, K.; Al-Qadasi, B.

2017-12-01

The dumpsite is underlain by highly fractured Precambrian basement complex of metamorphosed igneous and sedimentary rocks. Minor Tertiary, Quaternary basalts and Quaternary alluvial deposits overlie the basement rocks. Structurally, the area is affected by intersected series of north-to northwest trending faults. Hydrogeological setting of the study area is characterized by shallow groundwater aquifers in the fractured and weathered basement rocks. Moreover, the area exposes heavy rains especially during summer seasons, which may accelerate the transferring of contaminated water to the neighbouring valleys and low land. At present, the residential and Khamis Mushait new industrial zone are situated close to the dumpsite. The main objective of this study is to assess the leachate intrusion and groundwater contamination in the urban area of Khamis Mushait. Geophysical and geochemical techniques have been successfully applied in the assessment of environmental impact of dumpsites globally. Near-surface geophysical investigations such as Seismic refraction tomography, Schlumberger vertical electrical soundings (VES) and ground magnetic survey have been conducted to detect the controlling structures and lithological variation of the dumpsite. In addition, four water samples from hand dug wells and two surface water samples were collected from and around dumpsite. These water samples were analysed geochemically to inspect the presence of heavy metals, salts (sulphates, nitrates and chlorides), radioactive elements and physically to assess pH, TDS, DO, salinity, total hardness, turbidity, electrical conductivity and temperature. Results of VES illustrate low resistivity zones (≤ 30 Ohm-m) due to conductive leachate from dumpsite while seismic models and ground magnetic intensity map delineated fractures beneath the weathered basement layer which may provide pathways for the contaminants. The physico-chemical analysis of the collected groundwater samples revealed that there are considerable impacts of dumpsite leachate in the shallow groundwater. pH values of the representative samples indicate its unsuitability for human consumption. Leachate flow direction is oriented NNW-SSE and follows the similar flow pattern as deduced from hydrogeological investigation.

Lithospheric radial anisotropy beneath the Gulf of Mexico

NASA Astrophysics Data System (ADS)

Chu, Risheng; Ko, Justin Yen-Ting; Wei, Shengji; Zhan, Zhongwen; Helmberger, Don

2017-05-01

The Lithosphere-Asthenosphere Boundary (LAB), where a layer of low viscosity asthenosphere decouples with the upper plate motion, plays an essential role in plate tectonics. Most dynamic modeling assumes that the shear velocity can be used as a surrogate for viscosity which provides key information about mantle flow. Here, we derive a shear velocity model for the LAB structure beneath the Gulf of Mexico allowing a detailed comparison with that beneath the Pacific (PAC) and Atlantic (ATL). Our study takes advantage of the USArray data from the March 25th, 2013 Guatemala earthquake at a depth of 200 km. Such data is unique in that we can observe a direct upward traveling lid arrival which remains the first arrival ahead of the triplications beyond 18°. This extra feature in conjunction with upper-mantle triplication sampling allows good depth control of the LAB and a new upper-mantle seismic model ATM, a modification of ATL, to be developed. ATM has a prominent low velocity zone similar to the structure beneath the western Atlantic. The model contains strong radial anisotropy in the lid where VSH is about 6% faster than VSV. This anisotropic feature ends at the bottom of the lithosphere at about the depth of 175 km in contrast to the Pacific where it extends to over 300 km. Another important feature of ATM is the weaker velocity gradient from the depth of 175 to 350 km compared to Pacific models, which may be related to differences in mantle flow.

Shallow ground-water quality beneath cropland in the Red River of the North Basin, Minnesota and North Dakota, 1993-95

USGS Publications Warehouse

Cowdery, Timothy K.

1997-01-01

Land-use factors that increased nitrate and herbicide concentrations were greater tilled area, chemical application, irrigation, and cropland contiguity. Hydrogeological factors that increased these concentrations were a deeper watertable (higher oxygen concentration and less organic carbon), larger grain-size and degree of sorting of aquifer material (shorter time in the soil zone and aquifer), and fewer sulfur-containing minerals (lignite and pyrite) composing the aquifer. High rainfall, just before sampling of the Sheyenne Delta aquifer, contributed to the relatively low nitrate and pesticide concentrations in the shallow ground water of this aquifer by raising the water table higher into the soil zone, increasing ponded water (increasing biodegradation), preventing some chemical application (flooded fields), and leaching and then displacing nitrate-rich water downward, beneath new recharge. The shallow ground-water quality measured beneath cropland in these land-use study areas covers a large range. The land-use, hydrogeological, and rainfall factors controlling this quality also control shallow ground-water quality in other surficial aquifers in the Red River of the North Basin. Although not used for drinking water, 43% of the shallow ground water from the Otter Tail outwash aquifer was above the U.S. Environmental Protection Agency's nitrate maximum contaminant level of 10 mg/L-N, reducing its potential uses. These high nitrate concentrations do not threaten the Otter Tail outwash aquifer's surface-water bodies with eutrophication however, because significant denitrification occurs beneath riparian wetlands before ground water discharges to surface waters.

Hydrology of the solid waste burial ground as related to potential migration of radionuclides, Idaho National Engineering Laboratory

USGS Publications Warehouse

Barraclough, Jack T.; Robertson, J.B.; Janzer, V.J.; Saindon, L.G.

1976-01-01

A study was made (1970-1974) to evaluate the geohydrologic and geochemical controls on subsurface migration of radionuclides from pits and trenches in the Idaho National Engineering Laboratory (INEL) solid waste burial ground and to determine the existence and extent of radionuclide migration from the burial ground. A total of about 1,700 sediment, rock, and water samples were collected from 10 observation wells drilled in and near the burial ground of Idaho National Engineering Laboratory, formerly the National Reactor Testing Station (NRTS). Within the burial ground area, the subsurface rocks are composed principally of basalt. Wind- and water-deposited sediments occur at the surface and in beds between the thicker basalt zones. Two principal sediment beds occur at about 110 feet and 240 feet below the land surface. The average thickness of the surficial sedimentary layer is about 15 feet while that of the two principal subsurface layers is 13 and 14 feet, respectively. The water table in the aquifer beneath the burial ground is at a depth of about 580 feet. Fission, activation, and transuranic elements were detected in some of the samples from the 110- and 240-foot sedimentary layers. (Woodard-USGS)

Three Types of Earth's Inner Core Boundary

NASA Astrophysics Data System (ADS)

Tian, D.; Wen, L.

2017-12-01

The Earth's inner core boundary (ICB) is the site where the liquid outer core solidifies and the solid inner core grows. Thus, the fine-scale structure of the ICB is important for our understanding of the thermo-compositional state of the Earth's core. In this study, we collect a large set of seismic records with high-quality pre-critical PKiKP and PcP phase pairs, recorded by two dense seismic arrays, Hi-net in Japan and USArray in US. This dataset samples the ICB regions beneath East Asia, Mexico and the Bering Sea. We use differential travel times, amplitude ratios and waveform differences between PKiKP and PcP phases to constrain fine-scale structure of the ICB. The sampled ICB can be grouped into three types based on their seismic characteristics: (1) a simple ICB with a flat and sharp boundary, (2) a bumpy ICB with topographic height changes of 10 km, and (3) a localized mushy ICB with laterally varying thicknesses of 4-8 km. The laterally varying fine-scale structure of the ICB indicates existence of complex small-scale forces at the surface and a laterally varying solidification process of the inner core due to lateral variation of thermo-compositional condition near the ICB.

Protracted construction of gabbroic crust at a slow spreading ridge: Constraints from 206Pb/238U zircon ages from Atlantis Massif and IODP Hole U1309D (30°N, MAR)

USGS Publications Warehouse

Grimes, Craig B.; John, Barbara E.; Cheadle, Michael J.; Wooden, Joseph L.

2008-01-01

Sensitive high-resolution ion microprobe (SHRIMP) U-Pb zircon ages of 24 samples from oceanic crust recovered in Integrated Ocean Drilling Program (IODP) Hole U1309D and from the surface of Atlantis Massif, Mid-Atlantic Ridge (MAR) (30°N) document a protracted history of accretion in the footwall to an oceanic detachment fault. Ages for 18 samples of evolved Fe-Ti oxide gabbro and felsic dikes collected 40–1415 m below seafloor in U1309D yield a weighted mean of 1.20 ± 0.03 Ma (mean square of weighted deviates = 7.1). However, the ages range from 1.08 ± 0.07 Ma and 1.28 ± 0.05 Ma indicating crustal construction occurred over a minimum of 100–200 ka. The zircon ages, along with petrologic observations, indicate at least 2 major periods of intrusive activity with age peaks separated by 70 ka. The oldest ages are observed below 600 mbsf, an observation inconsistent with models requiring constant depth melt intrusion beneath a detachment fault. The data are most consistent with a “multiple sill” model whereby sills intrude at random depths below the ridge axis over a length scale greater than 1.4 km. Zircon ages from broadly spaced samples collected along the southern ridge of Atlantis Massif yield a detachment fault slip rate of 28.7 ± 6.7 mm/a and imply significant asymmetric plate spreading (up to 100% on the North American plate) for at least 200 ka during core complex formation.

Hydrogeology, groundwater seepage, nitrate distribution, and flux at the Raleigh hydrologic research station, Wake County, North Carolina, 2005-2007

USGS Publications Warehouse

McSwain, Kristen Bukowski; Bolich, Richard E.; Chapman, Melinda J.

2013-01-01

rom 2005 to 2007, the U.S. Geological Survey and the North Carolina Department of Environment and Natural Resources, Division of Water Quality, conducted a study to describe the geologic framework, measure groundwater quality, characterize the groundwater-flow system, and describe the groundwater/surface-water interaction at the 60-acre Raleigh hydrogeologic research station (RHRS) located at the Neuse River Waste Water Treatment Plant in eastern Wake County, North Carolina. Previous studies have shown that the local groundwater quality of the surficial and bedrock aquifers at the RHRS had been affected by high levels of nutrients. Geologic, hydrologic, and water-quality data were collected from 3 coreholes, 12 wells, and 4 piezometers at 3 well clusters, as well as from 2 surface-water sites, 2 multiport piezometers, and 80 discrete locations in the streambed of the Neuse River. Data collected were used to evaluate the three primary zones of the Piedmont aquifer (regolith, transition zone, and fractured bedrock) and characterize the interaction of groundwater and surface water as a mechanism of nutrient transport to the Neuse River. A conceptual hydrogeologic cross section across the RHRS was constructed using new and existing data. Two previously unmapped north striking, nearly vertical diabase dikes intrude the granite beneath the site. Groundwater within the diabase dike appeared to be hydraulically isolated from the surrounding granite bedrock and regolith. A correlation exists between foliation and fracture orientation, with most fractures striking parallel to foliation. Flowmeter logging in two of the bedrock wells indicated that not all of the water-bearing fractures labeled as water bearing were hydraulically active, even when stressed by pumping. Groundwater levels measured in wells at the RHRS displayed climatic and seasonal trends, with elevated groundwater levels occurring during the late spring and declining to a low in the late fall. Vertical gradients in the groundwater discharge area near the Neuse River were complex and were affected by fluctuations in river stage, with the exception of a well completed in a diabase dike. Water-quality data from the wells and surface-water sites at the RHRS were collected continuously as well as during periodic sampling events. Surface-water samples collected from a tributary were most similar in chemical composition to groundwater found in the regolith and transition zone. Nitrate (measured as nitrite plus nitrate, as nitrogen) concentrations in the sampled wells and tributary ranged from about 5 to more than 120 milligrams per liter as nitrogen. Waterborne continuous resistivity profiling conducted on the Neuse River in the area of the RHRS measured areas of low apparent resistivity that likely represent groundwater contaminated by high concentrations of nitrate. These areas were located on either side of a diabase dike and at the outfall of two unnamed tributaries. The diabase dike preferentially directed the discharge of groundwater to the Neuse River and may isolate groundwater movement laterally. Discrete temperature measurements made within the pore water beneath the Neuse River revealed seeps of colder groundwater discharging into warmer surface water near a diabase dike. Water-quality samples collected from the pore water beneath the Neuse River indicated that nitrate was present at concentrations as high as 80 milligrams per liter as nitrogen on the RHRS side of the river. The highest concentrations of nitrate were located within pore water collected from an area near a diabase dike that was identified as a suspected seepage area. Hydraulic head was measured and pore water samples were collected from two 140-centimeter-deep (55.1-inch-deep) multiport piezometers that were installed in bed sediments on opposite sides of a diabase dike. The concentration of nitrate in pore water at a suspected seepage area ranged from 42 to 82 milligrams per liter as nitrogen with a median concentration of 79 milligrams per liter as nitrogen. On the opposite side of the dike, concentrations of nitrate in pore water samples ranged from 3 to 91 milligrams per liter as nitrogen with a median concentration of 52 milligrams per liter. At one of the multiport piezometers the vertical gradient of hydraulic head between the Neuse River and the groundwater was too small to measure. At the multiport piezometer located in the suspected seepage area, an upward gradient of about 0.1 was present and explains the occurrence of higher concentrations of nitrate near the sediment/water interface. Horizontal seepage flux from the surficial aquifer to the edge of the Neuse River was estimated for 2006. Along a 130-foot flow path, the estimated seepage flux ranged from –0.52 to 0.2 foot per day with a median of 0.09 foot per day. The estimated advective horizontal mass flux of nitrate along a 300-foot reach of the Neuse River ranged from –10.9 to 5 pounds per day with a median of 2.2 pounds per day. The total horizontal mass flux of nitrate from the surficial aquifer to the Neuse River along the 130-foot flow path was estimated to be about 750 pounds for all of 2006. Seepage meters were deployed on the bed of the Neuse River in the areas of the multiport piezometers on either side of the diabase dike to estimate rates of vertical groundwater discharge and flux of nitrate. The average estimated daily seepage flux differed by two orders of magnitude between seepage areas. The potential vertical flux of nitrate from groundwater to the Neuse River was estimated at an average of 2.5 grams per day near one of the multiport piezometers and an average of 784 grams per day at the other. These approximations suggest that under some hydrologic conditions there is the potential for substantial quantities of nitrate to discharge from the groundwater to the Neuse River.

Genomic Evidence of Chemotrophic Metabolisms in Deep-Dwelling Chloroflexi Conferred by Ancient Horizontal Gene Transfer Events

NASA Astrophysics Data System (ADS)

Momper, L. M.; Magnabosco, C.; Amend, J.; Osburn, M. R.; Fournier, G. P.

2017-12-01

The marine and terrestrial subsurface biospheres represent quite likely the largest reservoirs for life on Earth, directly impacting surface processes and global cycles throughout Earth's history. In the deep subsurface biosphere (DSB) organic carbon and energy are often extremely scarce. However, archaea and bacteria are able to persist in the DSB to at least 3.5 km below surface [1]. Understanding how they persist, and by what metabolisms they subsist, are key questions in this biosphere. To address these questions we investigated 5 global DSB environments: one legacy mine in South Dakota, USA, 3 mines in South Africa and marine fluids circulating beneath the Juan de Fuca Ridge. Boreholes within these mines provided access to fluids buried beneath the earth's surface and sampled depths down to 3.1 km. Geochemical data were collected concomitantly with DNA for metagenomic sequencing. We examined genomes of the ancient and deeply branching Chloroflexi for metabolic capabilities and interrogated the geochemical drivers behind those metabolisms with in situ thermodynamic modeling of reaction energetics. In total, 23 Chloroflexi genomes were identified and analyzed from the 5 subsurface sites. Genes for nitrate reduction (nar) and sulfite reduction (dsr) were found in many of the South Africa Chloroflexi but were absent from genomes collected in South Dakota. Indeed, nitrate reduction was among the most energetically favorable reactions in South African fluids (10-14 kJ cell-1 sec -1 per mol of reactant) and sulfur reduction with Fe2+ or H2 was also exergonic [2]. Conversely, genes for nitrite and nitrous oxide reduction (nrf, nir and nos) were found in genomes collected in South Dakota and Juan de Fuca, but not South Africa. We examined the origin of genes conferring these metabolisms in the Chloroflexi genomes. We discovered evidence for horizontal gene transfer (HGT) for all of these putative metabolisms. Retention of these genes in Chloroflexi lineages indicates HGT may have conferred an advantageous metabolism in DSB environments. We are using molecular dating techniques to constrain the timing of these HGT events on geologic timescales. [1] Baker J. B. et al. (2003) Environ Microbiol., 5, 267-277. [2] Magnabosco C. et al. (2016) ISME J, 10(3), 730-741.

Solar heat collection with suspended metal roofing and whole house ventilation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maynard, T.

1996-10-01

A south pitched roof is employed for solar collection directly onto a roofing with chocolate brown color. The roofing is structural and is suspended over plywood decking so as to create an air space which receives input from the coolest and lowest basement air of the house interior. Air heated beneath the metal roofing is returned to a basement storage wall. Full length plenum cavities are formed into the ordinary rafter truss framing--at the knee wall and collar tie spaces. Preliminary testing of BTU gain at known air flows is acquired with a microprocessor system continuously collecting input and outputmore » temperatures at the roof collector into disk data files.« less

Ground-Water Flow, 2004-07, and Water Quality, 1992-2007, in McBaine Bottoms, Columbia, Missouri

USGS Publications Warehouse

Smith, Brenda Joyce; Richards, Joseph M.

2008-01-01

The U.S. Geological Survey, in cooperation with the city of Columbia, Missouri, and the Missouri Department of Conservation, collected ground-water quality data, surface-water quality data, and water-level data in McBaine Bottoms, southwest of Columbia. McBaine Bottoms, adjacent to the Missouri River, is the location of the municipal-supply well field for the city of Columbia, the city of Columbia wastewater-treatment wetlands, and the Missouri Department of Conservation Eagle Bluffs Conservation Area. This report describes the ground-water flow and water quality of McBaine Bottoms and provides information to better understand the interaction between treated effluent from the wetlands used on the Eagle Bluffs Conservation Area and the water in the alluvial aquifer that is pumped from the city of Columbia municipal-supply well field. Changes in major chemical constituent concentrations have been detected at several sampling sites between pre- and post-effluent application data. Analysis of post-effluent data indicates substantial changes in calcium, potassium, sodium, chloride, and sulfate concentrations in ground water. These changes became apparent shortly after the beginning of the operation of the wastewater-treatment wetland in 1994 and the formation of the Eagle Bluffs Conservation Area, which uses the treated effluent as a water source for the management of migratory water fowl. The changes have continued throughout the 15 years of sample collection. The concentrations of these major chemical constituents are on the mixing continuum between pre-effluent ground water as one end member and the treated wastewater effluent as the other end member. For monitoring wells that had changes in major chemical constituent concentrations, the relative percentage of treated effluent in the ground water, assuming chloride is conservative, ranged from 6 to 88 percent. Twenty-two monitoring wells throughout McBaine Bottoms have been affected by effluent based on chloride concentrations larger than 40 milligrams per liter. The chloride concentration of ground water in the alluvial aquifer reflects several sources, including precipitation, water from the Missouri River, water in the aquifer, and the treated effluent. Chloride concentrations from precipitation, the Missouri River, and water in the alluvial aquifer were less than 40 milligrams per liter. These monitoring wells affected by effluent are located in two general areas - adjacent to treatment wetland unit 1 and near the ground-water high on and north of the Eagle Bluffs Conservation Area. The probable source of the large chloride concentrations in well samples adjacent to treatment wetland unit 1 is leakage from the unit. The source for the large chloride concentrations in the other monitoring well samples is the effluent mixed with ground water and Missouri River water that is used to fill pools on the Eagle Bluffs Conservation Area. One monitoring well had a single sample with a chloride concentration larger than 40 milligrams per liter. That sample may have been affected by the use of road salt because of the presence of ice and snow immediately before the sample was collected. Lateral ground-water flow was dominated by the presence of a persistent ground-water high beneath the Eagle Bluffs Conservation Area and the presence of a cone of depression centered around the city of Columbia well field in the northern part of the study area. Ground-water flow was radially away from the apex of the ground-water high; west and south of the high, flow was toward the Missouri River, east of the high, flow was toward Perche Creek, and north of the high, flow was to the north toward the cone of depression around the city of Columbia well field. Another permanent feature on the water-level maps was a ground-water high beneath treatment wetland unit 1. Although the ground-water high was present throughout the study period, the subsurface expression of the high changed depending on hydrolo

Getting beneath the Veil of Effective Schools: Evidence from New York City. NBER Working Paper No. 17632

ERIC Educational Resources Information Center

Dobbie, Will; Fryer, Roland G., Jr.

2011-01-01

Charter schools were developed, in part, to serve as an R&D engine for traditional public schools, resulting in a wide variety of school strategies and outcomes. In this paper, we collect unparalleled data on the inner-workings of 35 charter schools and correlate these data with credible estimates of each school's effectiveness. We find that…

Hydrogeology, ground-water quality, and potential for water-supply contamination near the Shelby County landfill in Memphis, Tennessee

USGS Publications Warehouse

Parks, W.S.; Mirecki, J.E.

1992-01-01

An investigation was conducted from 1989 to 1991 to collect and interpret hydrogeologic and ground-water-quality data specific to the Shelby County landfill in east Memphis, Tennessee. Eighteen wells were installed in the alluvial and Memphis aquifers at the landfill. Hydrogeologic data collected showed that the confining unit separating the alluvial aquifer from the Memphis aquifer was thin or absent just north of the landfill and elsewhere consists predominantly of fine sand and silt with lenses of clay. A water-table map of the landfill vicinity confirms the existence of a depression in the water table north and northeast of the landfill and indicates that ground water flows northeast from the Wolf River passing beneath the landfill toward the depression in the water table. A map of the potentiometric surface of the Memphis aquifer shows that water levels were anomalously high just north of the landfill, indicating downward leakage of water from the alluvial aquifer to the Memphis aquifer. An analysis of water-quality data for major and trace inorganic constituents and nutrients confirms that leachate from the landfill has migrated northeastward in the alluvial aquifer toward the depression in the water table and that contaminants in the alluvial aquifer have migrated downward into the Memphis aquifer. The leachate plume can be characterized by concentrations of certain major and trace inorganic constituents that are 2 to 20 times higher than samples from upgradient and background alluvial aquifer wells. The major and trace constituents that best characterize the leachate plume are total organic carbon, chloride, dissolved solids, iron, ammonia nitrogen, calcium, sodium, iodide, barium, strontium, boron, and cadmium. Several of these constituents (specifically dissolved solids, calcium, sodium, and possibly ammonia nitrogen, chloride, barium, and strontium) were detected in elevated concentrations in samples from certain Memphis aquifer wells. Elevated concentrations were detected in samples from the Memphis aquifer beneath the leachate plume where the confining unit is thin or absent. The distribution of halogenated alkanes (specifically dichlorodifluoromethane and trichlorofluoromethane) and halogenated alkenes (specifically 1,2-trans-dichloroethene and vinyl chloride) in samples from wells screened in both the alluvial and Memphis aquifers is similar to the distribution of major and trace inorganic constituents that characterize the leachate plume. The ground-water supply most susceptible to contamination from the Shelby County landfill is the Sheahan well field of the Memphis Light, Gas and Water Division. This well field is about 5 miles downgradient from the landfill in the direction of ground-water flow. Based on an estimated velocity of 0.5 to 1.5 feet per day, ground water would require about 50 to 150 years to travel from the Shelby County landfill to the Sheahan wellfield. Given the time and distance of transport, any contaminants in the ground water would not likely persistto reach this well field because of the effects of various physical, chemical, and biological processes, including dilution and adsorption.

Tricholoma matsutake in a natural Pinus densiflora forest: correspondence between above- and below-ground genets, association with multiple host trees and alteration of existing ectomycorrhizal communities.

PubMed

Lian, Chunlan; Narimatsu, Maki; Nara, Kazuhide; Hogetsu, Taizo

2006-01-01

Tricholoma matsutake (matsutake) is an ectomycorrhizal (ECM) fungus that produces economically important mushrooms in Japan. Here, we use microsatellite markers to identify genets of matsutake sporocarps and below-ground ECM tips, as well as associated host genotypes of Pinus densiflora. We also studied ECM fungal community structure inside, beneath and outside the matsutake fairy rings, using morphological and internal transcribed spacer (ITS) polymorphism analysis. Based on sporocarp samples, one to four genets were found within each fairy ring, and no genetic differentiation among six sites was detected. Matsutake ECM tips were only found beneath fairy rings and corresponded with the genotypes of the above-ground sporocarps. We detected nine below-ground matsutake genets, all of which colonized multiple pine trees (three to seven trees per genet). The ECM fungal community beneath fairy rings was species-poor and significantly differed from those inside and outside the fairy rings. We conclude that matsutake genets occasionally establish from basidiospores and expand on the root systems of multiple host trees. Although matsutake mycelia suppress other ECM fungi during expansion, most of them may recover after the passage of the fairy rings.

Plant-based plume-scale mapping of tritium contamination in desert soils

USGS Publications Warehouse

Andraski, Brian J.; Stonestrom, David A.; Michel, R.L.; Halford, K.J.; Radyk, J.C.

2005-01-01

Plant-based techniques were tested for field-scale evaluation of tritium contamination adjacent to a low-level radioactive waste (LLRW) facility in the Amargosa Desert, Nevada. Objectives were to (i) characterize and map the spatial variability of tritium in plant water, (ii) develop empirical relations to predict and map subsurface contamination from plant-water concentrations, and (iii) gain insight into tritium migration pathways and processes. Plant sampling [creosote bush, Larrea tridentata (Sessé & Moc. ex DC.) Coville] required one-fifth the time of soil water vapor sampling. Plant concentrations were spatially correlated to a separation distance of 380 m; measurement uncertainty accounted for <0.1% of the total variability in the data. Regression equations based on plant tritium explained 96 and 90% of the variation in root-zone and sub-root-zone soil water vapor concentrations, respectively. The equations were combined with kriged plant-water concentrations to map subsurface contamination. Mapping showed preferential lateral movement of tritium through a dry, coarse-textured layer beneath the root zone, with concurrent upward movement through the root zone. Analysis of subsurface fluxes along a transect perpendicular to the LLRW facility showed that upward diffusive-vapor transport dominates other transport modes beneath native vegetation. Downward advective-liquid transport dominates at one endpoint of the transect, beneath a devegetated road immediately adjacent to the facility. To our knowledge, this study is the first to document large-scale subsurface vapor-phase tritium migration from a LLRW facility. Plant-based methods provide a noninvasive, cost-effective approach to mapping subsurface tritium migration in desert areas.

Middle Pleistocene interglacial Thames--Medway deposits at Clacton-on-Sea, England: Reconsideration of the biostratigraphical and environmental context of the type Clactonian Palaeolithic industry

NASA Astrophysics Data System (ADS)

Bridgland, David R.; Field, Michael H.; Holmes, Jonathan A.; McNabb, John; Preece, Richard C.; Selby, Ian; Wymer, John J.; Boreham, Steve; Irving, Brian G.; Parfitt, Simon A.; Stuart, Anthony J.

In 1987 an archaeological investigation was undertaken during redevelopment of the erstwhile Butlin's holiday camp at Clacton-on-Sea, on the grounds that the Middle Pleistocene Clacton Channel Deposits, containing the type-Clactonian Palaeolithic industry, were known to extend beneath the site. Excavations for a storm-drain allowed sampling at points along a longitudinal traverse of the main Clacton Channel. Analysis of these samples has provided new palaeontological information, including data pertaining to the rise in relative sea level during the interglacial represented. Systematic studies of molluscs and ostracods, the latter undertaken at Clacton for the first time, have been particularly valuable. Information from the Butlin's site supplements evidence previously gathered from the West Cliff section and from other localities at Clacton. The calcareous clay ('marl') that underlies the Clacton golf course extends beneath Butlin's, where it was found to be part of the Freshwater Beds, not the Estuarine Beds, as hitherto supposed. The Clacton Estuarine Beds, restricted to the eastern end of the site, have their base just below 2 m O.D., implying that their superposition upon the Clacton Freshwater Beds occurred when relative sea level in this area was close to present ordnance datum. Correlation of the Clacton Channel Deposits with the interglacial immediately following the Anglian/Elsterian Stage appears secure; equivalence with Oxygen Isotope Stage 11 of the oceanic sequence is most probable. A borehole survey and subsequent excavation revealed a Holocene sequence of unlithified tufa and organic sediments beneath part of the site.

P and S velocity structure of the crust and the upper mantle beneath central Java from local tomography inversion

NASA Astrophysics Data System (ADS)

Koulakov, I.; Bohm, M.; Asch, G.; Lühr, B.-G.; Manzanares, A.; Brotopuspito, K. S.; Fauzi, Pak; Purbawinata, M. A.; Puspito, N. T.; Ratdomopurbo, A.; Kopp, H.; Rabbel, W.; Shevkunova, E.

2007-08-01

Here we present the results of local source tomographic inversion beneath central Java. The data set was collected by a temporary seismic network. More than 100 stations were operated for almost half a year. About 13,000 P and S arrival times from 292 events were used to obtain three-dimensional (3-D) Vp, Vs, and Vp/Vs models of the crust and the mantle wedge beneath central Java. Source location and determination of the 3-D velocity models were performed simultaneously based on a new iterative tomographic algorithm, LOTOS-06. Final event locations clearly image the shape of the subduction zone beneath central Java. The dipping angle of the slab increases gradually from almost horizontal to about 70°. A double seismic zone is observed in the slab between 80 and 150 km depth. The most striking feature of the resulting P and S models is a pronounced low-velocity anomaly in the crust, just north of the volcanic arc (Merapi-Lawu anomaly (MLA)). An algorithm for estimation of the amplitude value, which is presented in the paper, shows that the difference between the fore arc and MLA velocities at a depth of 10 km reaches 30% and 36% in P and S models, respectively. The value of the Vp/Vs ratio inside the MLA is more than 1.9. This shows a probable high content of fluids and partial melts within the crust. In the upper mantle we observe an inclined low-velocity anomaly which links the cluster of seismicity at 100 km depth with MLA. This anomaly might reflect ascending paths of fluids released from the slab. The reliability of all these patterns was tested thoroughly.

Deep seismic structure and tectonics of northern Alaska: Crustal-scale duplexing with deformation extending into the upper mantle

USGS Publications Warehouse

Fuis, G.S.; Murphy, J.M.; Lutter, W.J.; Moore, Thomas E.; Bird, K.J.; Christensen, N.I.

1997-01-01

Seismic reflection and refraction and laboratory velocity data collected along a transect of northern Alaska (including the east edge of the Koyukuk basin, the Brooks Range, and the North Slope) yield a composite picture of the crustal and upper mantle structure of this Mesozoic and Cenozoic compressional orogen. The following observations are made: (1) Northern Alaska is underlain by nested tectonic wedges, most with northward vergence (i.e., with their tips pointed north). (2) High reflectivity throughout the crust above a basal decollement, which deepens southward from about 10 km depth beneath the northern front of the Brooks Range to about 30 km depth beneath the southern Brooks Range, is interpreted as structural complexity due to the presence of these tectonic wedges, or duplexes. (3) Low reflectivity throughout the crust below the decollement is interpreted as minimal deformation, which appears to involve chiefly bending of a relatively rigid plate consisting of the parautochthonous North Slope crust and a 10- to 15-km-thick section of mantle material. (4) This plate is interpreted as a southward verging tectonic wedge, with its tip in the lower crust or at the Moho beneath the southern Brooks Range. In this interpretation the middle and upper crust, or all of the crust, is detached in the southern Brooks Range by the tectonic wedge, or indentor: as a result, crust is uplifted and deformed above the wedge, and mantle is depressed and underthrust beneath this wedge. (5) Underthrusting has juxtaposed mantle of two different origins (and seismic velocities), giving rise to a prominent sub-Moho reflector. Copyright 1997 by the American Geophysical Union.

A multi-analytical approach for the characterization of wall painting materials on contemporary buildings

NASA Astrophysics Data System (ADS)

Magrini, Donata; Bracci, Susanna; Cantisani, Emma; Conti, Claudia; Rava, Antonio; Sansonetti, Antonio; Shank, Will; Colombini, MariaPerla

2017-02-01

Samples from Keith Haring's wall painting of the Necker Children Hospital in Paris were studied by a multi-analytical protocol. X-ray fluorescence (XRF), powder X-ray diffraction (XRDP), Electron microscope (SEM-EDS), Infrared and Raman spectroscopy (μ-FT-IR and μ-Raman) measurements were performed in order to characterize the materials and to identify the art technique used to produce this contemporary work. Materials from the mural suffered from severe detachments of materials and several fragments were found on the ground beneath. Some of these fragments, which were representative of the whole palette and stratigraphic sequence, were collected and studied. The fragments were sufficiently large to enable non-invasive measurements to be performed in order to characterize the materials. A comparison of the data of the techniques applied revealed that Haring's palette was composed of organic pigments such as Naphtol red, phthalocyanine blue and green and Hansa yellow, in accordance with those used previously by the artist in other painted murals.

Geophysical and geochemical data from the area of the Pebble Cu-Au-Mo porphyry deposit, southwestern Alaska: Contributions to assessment techniques for concealed mineral resources

USGS Publications Warehouse

Anderson, E.D.; Smith, S.M.; Giles, S.A.; Granitto, Matthew; Eppinger, R.G.; Bedrosian, P.A.; Shah, A.K.; Kelley, K.D.; Fey, D.L.; Minsley, B.J.; Brown, P.J.

2011-01-01

In 2007, the U.S. Geological Survey began a multidisciplinary study in southwest Alaska to investigate the setting and detectability of mineral deposits in concealed volcanic and glacial terranes. The study area hosts the world-class Pebble porphyry Cu-Au-Mo deposit, and through collaboration with the Pebble Limited Partnership, a range of geophysical and geochemical investigations was carried out in proximity to the deposit. The deposit is almost entirely concealed by tundra, glacial deposits, and post-mineralization volcanic rocks. The discovery of mineral resources beneath cover is becoming more important because most of the mineral resources at the surface have already been discovered. Research is needed to identify ways in which to assess for concealed mineral resources. This report presents the uninterpreted geophysical measurements and geochemical and mineralogical analytical data from samples collected during the summer field seasons from 2007 to 2010, and makes the data available in a single Geographic Information System (GIS) database.

Effect of nutrient enrichment on the source and composition of sediment organic carbon in tropical seagrass beds in the South China Sea.

PubMed

Liu, Songlin; Jiang, Zhijian; Zhang, Jingping; Wu, Yunchao; Lian, Zhonglian; Huang, Xiaoping

2016-09-15

To assess the effect of nutrient enrichment on the source and composition of sediment organic carbon (SOC) beneath Thalassia hemprichii and Enhalus acoroides in tropical seagrass beds, Xincun Bay, South China Sea, intertidal sediment, primary producers, and seawater samples were collected. No significant differences on sediment δ(13)C, SOC, and microbial biomass carbon (MBC) were observed between T. hemprichii and E. acoroides. SOC was mainly of autochthonous origin, while the contribution of seagrass to SOC was less than that of suspended particulate organic matter, macroalgae and epiphytes. High nutrient concentrations contributed substantially to SOC of seagrass, macroalgae, and epiphytes. The SOC, MBC, and MBC/SOC ratio in the nearest transect to fish farming were the highest. This suggested a more labile composition of SOC and shorter turnover times in higher nutrient regions. Therefore, the research indicates that nutrient enrichment could enhance plant-derived contributions to SOC and microbial use efficiency. Copyright © 2016 Elsevier Ltd. All rights reserved.

Hydrogeochemie und geogene Fluorid- und Borproblematik des Emschermergels im Münsterland

NASA Astrophysics Data System (ADS)

Wisotzky, Frank; Droste, Björn; Banning, Andre

2017-03-01

The hydrogeochemistry of the Cretaceous Emscher Fm. in northwest Germany was investigated, including analysis of 160 rock samples for carbon and sulfur content. Beneath a weathered zone, unweathered rocks containing pyrite were found. Groundwater data from the Emscher Fm. (580 analyses of house wells and additional literature data) were collected and evaluated. Some groundwater contains high fluoride and boron concentrations of up to 10 mg/l. Regionally, up to 30% of house wells show fluoride concentrations above 1.5 mg/l, and up to 50% above 1 mg/l boron. The spatial distribution depends on the presence of Quaternary cover sediments. Groundwater with high fluoride concentrations displays low Ca2+, and vice versa, indicating equilibrium with the mineral fluorite (CaF2). Concentrations above drinking water guidelines almost exclusively occur in ion exchange waters of the Na-HCO3 -(Cl) type with pH > 7.5. The main mobilization mechanism of both contaminants appears to be pH-triggered desorption from mineral surfaces.

Shear wave velocity structure in North America from large-scale waveform inversions of surface waves

USGS Publications Warehouse

Alsina, D.; Woodward, R.L.; Snieder, R.K.

1996-01-01

A two-step nonlinear and linear inversion is carried out to map the lateral heterogeneity beneath North America using surface wave data. The lateral resolution for most areas of the model is of the order of several hundred kilometers. The most obvious feature in the tomographic images is the rapid transition between low velocities in the technically active region west of the Rocky Mountains and high velocities in the stable central and eastern shield of North America. The model also reveals smaller-scale heterogeneous velocity structures. A high-velocity anomaly is imaged beneath the state of Washington that could be explained as the subducting Juan de Fuca plate beneath the Cascades. A large low-velocity structure extends along the coast from the Mendocino to the Rivera triple junction and to the continental interior across the southwestern United States and northwestern Mexico. Its shape changes notably with depth. This anomaly largely coincides with the part of the margin where no lithosphere is consumed since the subduction has been replaced by a transform fault. Evidence for a discontinuous subduction of the Cocos plate along the Middle American Trench is found. In central Mexico a transition is visible from low velocities across the Trans-Mexican Volcanic Belt (TMVB) to high velocities beneath the Yucatan Peninsula. Two elongated low-velocity anomalies beneath the Yellowstone Plateau and the eastern Snake River Plain volcanic system and beneath central Mexico and the TMVB seem to be associated with magmatism and partial melting. Another low-velocity feature is seen at depths of approximately 200 km beneath Florida and the Atlantic Coastal Plain. The inversion technique used is based on a linear surface wave scattering theory, which gives tomographic images of the relative phase velocity perturbations in four period bands ranging from 40 to 150 s. In order to find a smooth reference model a nonlinear inversion based on ray theory is first performed. After correcting for the crustal thickness the phase velocity perturbations obtained from the subsequent linear waveform inversion for the different period bands are converted to a three-layer model of S velocity perturbations (layer 1, 25-100 km; layer 2, 100-200 km) layer 3, 200-300 km). We have applied this method on 275 high-quality Rayleigh waves recorded by a variety of instruments in North America (IRIS/USGS, IRIS/IDA, TERRAscope, RSTN). Sensitivity tests indicate that the lateral resolution is especially good in the densely sampled western continental United States, Mexico, and the Gulf of Mexico.

Multi Plumes and Their Flows beneath Arabia and East Africa

NASA Astrophysics Data System (ADS)

Chang, S.; van der Lee, S.

2010-12-01

The three-dimensional S-velocity structure beneath Arabia and East Africa is estimated down to the lower mantle to investigate vertical and horizontal extension of low-velocity anomalies that bear out the presence of mantle plumes and their flows beneath lithosphere. We estimated this model through joint inversion of teleseismic S- and SKS-arrival times, regional S- and Rayleigh waveform fits, fundamental-mode Rayleigh-wave group velocities, and independent Moho constraints from receiver functions, reflection/refraction profiles, and gravity measurements. With the unprecedented resolution in our S-velocity model, we found different flow patterns of hot materials upwelling beneath Afar beneath the Red Sea and the Gulf of Aden. While the low-velocity anomaly from Afar is well confined beneath the Gulf of Aden, inferring mantle flow along the gulf, N-S channel of low velocity is found beneath Arabia, not along the Red Sea. The Afar plume is distinctively separate from the Kenya plume, showing its origin in the lower mantle beneath southwestern Arabia. We identified another low-velocity extension to the lower mantle beneath Jordan and northern Arabia, which is thought to have caused volcanism in Jordan, northern Arabia, and possibly southern Turkey. Comparing locations of mantle plumes from the joint inversion with fast axes of shear-wave splitting, we confirmed horizontal plume flow from Afar in NS direction beneath Arabia and in NE-SW direction beneath Ethiopia as a likely cause of the observed seismic anisotropy.

Mezozooplankton Beneath the Summer Sea Ice in McMurdo Sound, Antarctica: Abundance, Species Composition, and DMSP content

EPA Science Inventory

The Ross Sea Phaeocystis antarctica bloom contributes to a summer increase in under-ice planton biomass in McMurdo Sound, Antarctica. Due to difficulties of under-ice sampling, information on the mesozooplankton in McMurdo Sound is limited. We measured the abundance of mesooopl...

TEMPORAL MOISTURE CONTENT VARIABILITY BENEATH AND EXTERNAL TO A BUILDING AND THE POTENTIAL EFFECTS ON VAPOR INTRUSION RISK ASSESSMENT

EPA Science Inventory

Migration of vapors from organic chemicals residing in the subsurface into overlying buildings is known as vapor intrusion. Because of the difficulty in evaluating vapor intrusion by indoor air sampling, models are often employed to determine if a potential indoor inhalation exp...

Inferences on the hydrothermal system beneath the resurgent dome in Long Valley Caldera, east-central California, USA, from recent pumping tests and geochemical sampling

USGS Publications Warehouse

Farrar, C.D.; Sorey, M.L.; Roeloffs, E.; Galloway, D.L.; Howle, J.F.; Jacobson, R.

2003-01-01

Quaternary volcanic unrest has provided heat for episodic hydrothermal circulation in the Long Valley caldera, including the present-day hydrothermal system, which has been active over the past 40 kyr. The most recent period of crustal unrest in this region of east-central California began around 1980 and has included periods of intense seismicity and ground deformation. Uplift totaling more than 0.7 m has been centered on the caldera's resurgent dome, and is best modeled by a near-vertical ellipsoidal source centered at depths of 6-7 km. Modeling of both deformation and microgravity data now suggests that (1) there are two inflation sources beneath the caldera, a shallower source 7-10 km beneath the resurgent dome and a deeper source ???15 km beneath the caldera's south moat and (2) the shallower source may contain components of magmatic brine and gas. The Long Valley Exploration Well (LVEW), completed in 1998 on the resurgent dome, penetrates to a depth of 3 km directly above this shallower source, but bottoms in a zone of 100??C fluid with zero vertical thermal gradient. Although these results preclude extrapolations of temperatures at depths below 3 km, other information obtained from flow tests and fluid sampling at this well indicates the presence of magmatic volatiles and fault-related permeability within the metamorphic basement rocks underlying the volcanic fill. In this paper, we present recently acquired data from LVEW and compare them with information from other drill holes and thermal springs in Long Valley to delineate the likely flow paths and fluid system properties under the resurgent dome. Additional information from mineralogical assemblages in core obtained from fracture zones in LVEW documents a previous period of more vigorous and energetic fluid circulation beneath the resurgent dome. Although this system apparently died off as a result of mineral deposition and cooling (and/or deepening) of magmatic heat sources, flow testing and tidal analyses of LVEW water level data show that relatively high permeability and strain sensitivity still exist in the steeply dipping principal fracture zone penetrated at a depth of 2.6 km. The hydraulic properties of this zone would allow a pressure change induced at distances of several kilometers below the well to be observable within a matter of days. This indicates that continuous fluid pressure monitoring in the well could provide direct evidence of future intrusions of magma or high-temperature fluids at depths of 5-7 km. ?? 2003 Elsevier B.V. All rights reserved.

Dimensionality Analysis and Geo-Electric Structure of Long-period Magnetotelluric Data, Southern Taiwan, TAIGER project

NASA Astrophysics Data System (ADS)

Chiang, C.; Chen, C.; Bertrand, E. A.; Unsworth, M. J.; Turkoglu, E.; Hsu, H.; Hill, G.

2007-12-01

The Taiwan orogen has formed as a result of the arc-continent collision between the Eurasian continental margin and the Luzon island arc over the last 3 million years. It is the type example of an arc-continent collision. In 2004, the Taiwan Integrated Geodynamical Research (TAIGER) project was formed and began a systematic investigation of the crustal and upper mantle structure beneath Taiwan. This included new magnetotelluric (MT) data collection to study the geo-electrical structure beneath Taiwan. High quality long period MT data has been collected through collaboration between National Central University, Taiwan, and the University of Alberta, Canada. In total, 82 long-period MT stations were deployed on 4 cross- island profiles in Taiwan with a remote reference station located on Penghu Island in the Taiwan Strait. The remote reference is ~50km from the main island of Taiwan and is used to reduce cultural noise effects in these data from the populated mainland. Dimensionality analysis from tensor decomposition has been performed on these data using the McNeice-Jones algorithm. The results of this analysis indicate that the electrical structures are two-dimensional with dominant strike directions N45° E, N37° E and N29 ° E in northern, central and southern Taiwan, respectively. As expected, these strike directions are essentially parallel to the regional geology. The decomposition parameters of shear, twist and anisotropy for these profiles are small, indicating the 2-D strike directions are well constrained. The dimensionality analysis presented implies that the generation of 2- D inversion models will be appropriate for these data. The results of 2-D inversion show that the collision boundary between the Eurasian and Philippine Sea Plates is beneath the central range in the southern profile. A low resistivity zone is located beneath the western foothills. At mid-crustal depth, a boundary is imaged between conductive western sedimentary rocks and the resistive metamorphic rocks to the east which form the main orogenic belts of the central ranges. This margin occurs near the trace of the Cauchow fault where there is evidence of a conductor rising to the surface. This conductor may be related to interconnected fluids and/or thermal effects in the mid crust. In this paper, the analysis of these data will be examined in detail and the tectonic implications discussed.

3D velocity imaging of Hikurangi subduction beneath the Wellington region, New Zealand

NASA Astrophysics Data System (ADS)

Wech, A.; Henrys, S. A.; Sutherland, R.; Seward, A. M.; Stern, T. A.; Sato, H.; Okaya, D. A.; Bassett, D.

2011-12-01

We present first results from the Seismic Array HiKurangi Experiment (SAHKE). This joint project involving institutions from New Zealand, Japan and the USA aims to investigate the subduction zone fault characteristics beneath the southernmost part of New Zealand's North Island. Situated above where the Pacific Plate is subducting beneath the Australian plate at a rate of ~42 mm/yr, the Wellington region provides a unique opportunity to investigate the frictional properties, geometry, and seismic potential of a shallow, locked megathrust fault. Here the coupled plate interface is 20-30 km deep beneath land and can be sampled with onshore-offshore data from 3 sides. An added interest to this project is that the elevated, oceanic, Hikurangi plateau has entered the subduction zone, east of Wellington, but it is still unclear how far the plateau has advanced westward into the subduction zone. SAHKE combines active and passive source data comprising 4 distinct data sets. 1) A dense temporary array of 50 seismometers with ~7 km spacing augmented 25 regional network instruments to record 49 local and 45 teleseismic earthquakes over a four month period. 2) These stations also recorded 69,000 offshore airgun shots from 17 lines crisscrossing two sides of the array. 3) An additional coast-to-coast transect of 50 stations cutting through the temporary array recorded ~2000 offshore shots on either side. 4) 1000 stations with 100m spacing along that same transect separately recorded 12 in-line, 500 kg onshore dynamite explosions. First inspection of the recent onshore shot gathers show excellent signal to noise and a band of three strong reflectors between 20 and 38 km at the western end of the profile. We combine shot and earthquake recordings to simultaneously invert ~750,000 first arrivals for velocity structure and hypocenters in the densely sampled volume. First results from 3D, Vp tomography and relocated hypocenters agree with previous studies and suggest the later weak signals are reflections from the top of the Pacific plate. Our improved velocity model provides a high-resolution geometry of the subducting plate to support interpretation of other phases identified in SAHKE shot gathers.

The source of groundwater and solutes to Many Devils Wash at a former uranium mill site in Shiprock, New Mexico

USGS Publications Warehouse

Robertson, Andrew J.; Ranalli, Anthony J.; Austin, Stephen A.; Lawlis, Bryan R.

2016-04-21

The Shiprock Disposal Site is the location of the former Navajo Mill (Mill), a uranium ore-processing facility, located on a terrace overlooking the San Juan River in the town of Shiprock, New Mexico. Following the closure of the Mill, all tailings and associated materials were encapsulated in a disposal cell built on top of the former Mill and tailings piles. The milling operations, conducted at the site from 1954 to 1968, created radioactive tailings and process-related wastes that are now found in the groundwater. Elevated concentrations of constituents of concern—ammonium, manganese, nitrate, selenium, strontium, sulfate, and uranium—have also been measured in groundwater seeps in the nearby Many Devils Wash arroyo, leading to the inference that these constituents originated from the Mill. These constituents have also been reported in groundwater that is associated with Mancos Shale, the bedrock that underlies the site. The objective of this report is to increase understanding of the source of water and solutes to the groundwater beneath Many Devils Wash and to establish the background concentrations for groundwater that is in contact with the Mancos Shale at the site. This report presents evidence on three working hypotheses: (1) the water and solutes in Many Devils Wash originated from the operations at the former Mill, (2) groundwater in deep aquifers is upwelling under artesian pressure to recharge the shallow groundwater beneath Many Devils Wash, and (3) the groundwater beneath Many Devils Wash originates as precipitation that infiltrates into the shallow aquifer system and discharges to Many Devils Wash in a series of springs on the east side of the wash. The solute concentrations in the shallow groundwater of Many Devils Wash would result from the interaction of the water and the Mancos Shale if the source of water was upwelling from deep aquifers or precipitation.In order to compare the groundwater from various wells to groundwater that has been affected by Mill activities, a classification system was developed to determine which wells were most likely to have been affected. Affects to groundwater by the Mill were determined by using the reported uranium alpha activity ratios measured in groundwater samples, along with the concentration of the uranium and the location of the wells relative to the Mill. Activity ratios of 1.2 or less were determined to be the most reliable indicator of Mill-affected groundwater. Wells with samples that had a reported activity ratio of 1.2 or less were classified as Mill affected. To compare groundwater with background water-quality, data from groundwater seeps and springs in the Upper Eagle Nest Arroyo and Salt Creek Wash, located north of the San Juan River, are also presented and analyzed.Based on groundwater elevations and tritium concentrations measured in wells located between the disposal cell and Many Devils Wash, Mill water is not likely to reach Many Devils Wash. The tritium concentrations also indicate that groundwater from the Mill has not substantially affected Many Devils Wash in the past. Upwelling from deep aquifers was also determined to be an unlikely source, primarily by comparing the composition of the stable isotopes of water in the shallow groundwater with those reported in groundwater samples from the deeper aquifers. The stable-isotope compositions of the shallow groundwater around the site are enriched relative to the San Juan River and local meteoric lines, which suggests that most of the shallow groundwater has been influenced by evaporation and therefore was recharged at the surface. Several observations indicate that focused recharge is the likely source of groundwater in the area of Many Devils Wash. The visible erosional features in Many Devils Wash provide evidence of piping and groundwater sapping, and the distribution and type of vegetation in Many Devils Wash suggest that the focused recharge of precipitation is occurring. The estimated recharge from precipitation was calculated to be 0.0008 inches per year (in/yr) by using the mass-balance approach from reported seep discharge and 0.0011 in/yr using the chloride mass-balance approach.A conceptual model of groundwater quality beneath Many Devils Wash is presented to explain the source of solutes in the groundwater beneath Many Devils Wash. The major-ion concentrations and geochemical evolution in the groundwater beneath Many Devils Wash and across the study area support the conceptual model that the underlying Mancos Shale is the source of solutes. Differences in the major-ion composition between groundwater samples collected around the site, result from the degree of weathering to the Mancos Shale. The cation distribution appears to be an indicator of effects from the Mill, with samples from the Mill-affected wells largely having a calcium/magnesium-sulfate composition that resembles the reported compositions of more weathered shale; however, that composition could change if the Mill-processed water flowed into areas where the Mancos Shale was less weathered. On the basis of the widespread presence of uranium in the Mancos Shale and the distribution of aqueous uranium in the analog sites and other sites in the region, it appears likely that uranium in the groundwater of Many Devils Wash is naturally sourced from the Mancos Shale.

Imaging paleoslabs in the D″ layer beneath Central America and the Caribbean using seismic waveform inversion.

PubMed

Borgeaud, Anselme F E; Kawai, Kenji; Konishi, Kensuke; Geller, Robert J

2017-11-01

D″ (Dee double prime), the lowermost layer of the Earth's mantle, is the thermal boundary layer (TBL) of mantle convection immediately above the Earth's liquid outer core. As the origin of upwelling of hot material and the destination of paleoslabs (downwelling cold slab remnants), D″ plays a major role in the Earth's evolution. D″ beneath Central America and the Caribbean is of particular geodynamical interest, because the paleo- and present Pacific plates have been subducting beneath the western margin of Pangaea since ~250 million years ago, which implies that paleoslabs could have reached the lowermost mantle. We conduct waveform inversion using a data set of ~7700 transverse component records to infer the detailed three-dimensional S-velocity structure in the lowermost 400 km of the mantle in the study region so that we can investigate how cold paleoslabs interact with the hot TBL above the core-mantle boundary (CMB). We can obtain high-resolution images because the lowermost mantle here is densely sampled by seismic waves due to the full deployment of the USArray broadband seismic stations during 2004-2015. We find two distinct strong high-velocity anomalies, which we interpret as paleoslabs, just above the CMB beneath Central America and Venezuela, respectively, surrounded by low-velocity regions. Strong low-velocity anomalies concentrated in the lowermost 100 km of the mantle suggest the existence of chemically distinct denser material connected to low-velocity anomalies in the lower mantle inferred by previous studies, suggesting that plate tectonics on the Earth's surface might control the modality of convection in the lower mantle.

The Holocene Minimum of the West Antarctic Ice Sheet: Radiocarbon Model Ages for Subglacial Sediments

NASA Astrophysics Data System (ADS)

Tulaczyk, S. M.; Stansell, N.; Scherer, R. P.; Powell, R. D.

2017-12-01

It is commonly assumed that the West Antarctic Ice Sheet (WAIS) is at the present time as small as it has been since at least the last interglacial period about 125,000 years ago. Yet, our recent analyses of subglacial sediments recovered from beneath the ice sheet indicate regionally widespread presence of radiocarbon. This unstable isotope with half life of 5,730 years should decay to nil if the analyzed subglacial sediment samples have been isolated beneath the ice sheet from the atmosphere and the ocean for 125,000 years (over 20 half lives). However, the apparent radiocarbon ages for these samples are in the range of about 20,000-30,000 years BP, based on radiocarbon Fraction Modern (FM) of a few to several percent. The apparent sediment ages cannot be taken at face value because: (1) they overlap with the Last Glacial Maximum (LGM) when WAIS is known to have extended over 1,000 km past the sediment sampling locations, and (2) Antarctic glacigenic sediments commonly contain significant admixture of old, radiocarbon-dead organic matter. The latter biases apparent radiocarbon ages because it violates the assumption that the initial radiocarbon fraction in a sample was equal to FM. To mitigate the problem with apparent ages, we assume that initial radiocarbon fraction in subglacial sediments was equal to that determined by us independently in J-9 sediments from beneath the Ross Ice Shelf (RIS) and calculate radiocarbon 'model ages' between 1,000 and 6,000 years BP. This period of time overlaps with a regional climatic optimum and with late phases of post-LGM glacioisostatic adjustment in the region (e.g., Kingslake et al., this session). We propose that the grounding line of WAIS, at least on the RIS side, retreated in mid/late Holocene more than 300 km beyond its current position and then re-advanced to reach its modern geometry. This implies that the main body of WAIS was significantly smaller than today in mid/late Holocene and that the ice sheet is capable of large fluctuations on timescales much shorter than previously expected.

Soil water stable isotopes reveal evaporation dynamics at the soil-plant-atmosphere interface of the critical zone

NASA Astrophysics Data System (ADS)

Sprenger, Matthias; Tetzlaff, Doerthe; Soulsby, Chris

2017-07-01

Understanding the influence of vegetation on water storage and flux in the upper soil is crucial in assessing the consequences of climate and land use change. We sampled the upper 20 cm of podzolic soils at 5 cm intervals in four sites differing in their vegetation (Scots Pine (Pinus sylvestris) and heather (Calluna sp. and Erica Sp)) and aspect. The sites were located within the Bruntland Burn long-term experimental catchment in the Scottish Highlands, a low energy, wet environment. Sampling took place on 11 occasions between September 2015 and September 2016 to capture seasonal variability in isotope dynamics. The pore waters of soil samples were analyzed for their isotopic composition (δ2H and δ18O) with the direct-equilibration method. Our results show that the soil waters in the top soil are, despite the low potential evaporation rates in such northern latitudes, kinetically fractionated compared to the precipitation input throughout the year. This fractionation signal decreases within the upper 15 cm resulting in the top 5 cm being isotopically differentiated to the soil at 15-20 cm soil depth. There are significant differences in the fractionation signal between soils beneath heather and soils beneath Scots pine, with the latter being more pronounced. But again, this difference diminishes within the upper 15 cm of soil. The enrichment in heavy isotopes in the topsoil follows a seasonal hysteresis pattern, indicating a lag time between the fractionation signal in the soil and the increase/decrease of soil evaporation in spring/autumn. Based on the kinetic enrichment of the soil water isotopes, we estimated the soil evaporation losses to be about 5 and 10 % of the infiltrating water for soils beneath heather and Scots pine, respectively. The high sampling frequency in time (monthly) and depth (5 cm intervals) revealed high temporal and spatial variability of the isotopic composition of soil waters, which can be critical, when using stable isotopes as tracers to assess plant water uptake patterns within the critical zone or applying them to calibrate tracer-aided hydrological models either at the plot to the catchment scale.

A Gradient in Cooling Rate Beneath the Moho at the Oman Ophiolite: Fresh Insights into Cooling Processes at Mid-Ocean Ridges from REE-Based Thermometry

NASA Astrophysics Data System (ADS)

Dygert, N. J.; Kelemen, P. B.; Liang, Y.

2015-12-01

The Wadi Tayin massif in the southern Oman ophiolite has a more than 10 km thick mantle section and is believed to have formed in a mid-ocean ridge like environment with an intermediate to fast spreading rate. Previously, [1] used major element geothermometers to investigate spatial variations in temperatures recorded in mantle peridotites and observed that samples near the paleo-Moho have higher closure temperatures than samples at the base of the mantle section. Motivated by these observations, we measured major and trace elements in orthopyroxene and clinopyroxene in peridotites from depths of ~1-8km beneath the Moho to determine closure temperatures of REE in the samples using the REE-in-two-pyroxene thermometer [2]. Clinopyroxene are depleted in LREE and have REE concentrations that vary depending on distance from the Moho. Samples nearer the Moho have lower REE concentrations than those deeper in the section (e.g., chondrite normalized Yb ranges from ~1.5 at the Moho to 4 at 8km depth), consistent with near fractional melting along a mantle adiabat. Orthopyroxene are highly depleted in LREE but measurements of middle to heavy REE have good reproducibility. We find that REE-in-two-pyroxene temperatures decrease with increasing distance from the Moho, ranging from 1325±10°C near the Moho to 1063±24°C near the base of the mantle section. Using methods from [3], we calculate cooling rates of >1000°C/Myr near the Moho, dropping to rates of <10°C/Myr at the bottom of the section. The faster cooling rate is inconsistent with conductive cooling models. Fast cooling of the mantle lithosphere could be facilitated by infiltration of seawater to or beneath the petrologic Moho. This can explain why abyssal peridotites from ultra-slow spreading centers (which lack a crustal section) have cooling rates comparable to those of Oman peridotites [3]. [1] Hanghøj et al. (2010), JPet 51(1-2), 201-227. [2] Liang et al. (2013), GCA 102, 246-260. [3] Dygert & Liang (2015), EPSL 420, 151-161.

New seismic observation on the lithosphere and slab subduction beneath the Indo-Myanmar block: Implications for continent oblique subduction and transition to oceanic slab subduction

NASA Astrophysics Data System (ADS)

Jiang, M.; He, Y.; Zheng, T.; Mon, C. T.; Thant, M.; Hou, G.; Ai, Y.; Chen, Q. F.; Sein, K.

2017-12-01

The Indo-Myanmar block locates to the southern and southeastern of the Eastern Himalayan Syntax (EHS) and marks a torsional boundary of the collision between the Indian and Eurasian plates. There are two fundamental questions concerned on the tectonics of Indo-Myanmar block since the Cenozoic time. One is whether and how the oblique subduction is active in the deep; the other is where and how the transition from oceanic subduction and continental subduction operates. However, the two problems are still under heated debate mainly because the image of deep structure beneath this region is still blurring. Since June, 2016, we have executed the China-Myanmar Geophysical Survey in the Myanmar Orogen (CMGSMO) and deployed the first portable seismic array in Myanmar in cooperation with Myanmar Geosciences Society (MGS). This array contains 70 stations with a dense-deployed main profile across the Indo-Myanmar Range, Central Basin and Shan State Plateau along latitude of 22° and a 2-D network covering the Indo-Myanmar Range and the western part of the Central Basin. Based on the seismic data collected by the new array, we conducted the studies on the lithospheric structure using the routine surface wave tomography and receiver function CCP stacking. The preliminary results of surface wave tomography displayed a remarkable high seismic velocity fabric in the uppermost of mantle beneath the Indo-Myanmar Range and Central Basin, which was interpreted as the subducted slab eastward. Particularly, we found a low velocity bulk within the high-velocity slab, which was likely to be a slab window due to the slab tearing. The preliminary results of receiver function CCP stacking showed the obvious variations of the lithospheric structures from the Indo-Myanmar Range to the Central Basin and Shan State Plateau. The lithospheric structure beneath the Indo-Myanmar Range is more complex than that beneath the Central Basin and Shan State Plateau. Our resultant high-resolution images will provide important constrains for establishing the tectonic framework of Indian plate eastward subduction. This study is supported by the National Natural Science Foundation of China (grants 41490612, 41274002).

Teleseismic tomography beneath the mid-lower Yangtze region in China

NASA Astrophysics Data System (ADS)

Jiang, G.; Zhang, G.; Lu, Q.; Shi, D.

2010-12-01

We have applied the teleseismic tomography method proposed by Professor Zhao in 1994 to determine a 3-D P-wave velocity structure of the mantle down to 400 km depth beneath the mid-lower Yangtze region, by using 1508 P-wave arrival times collected from 46 teleseismic events recorded by 38 portable seismic stations in this region (Fig. 1). All the seismograms were recorded only for 5 months from November 2009 to March 2010. Most events located to the south and southeast of stations, and the stations almost align in a line, which causes the rays crossing not well and decreases the resolution in the depth, especially beneath the region in the north-west of the stations. All the relative arrival times were obtained by using the multi-channel cross-correlation method with higher precisions than by hand-picking. Our tomographic result along the profile line of OO’ shows that the lithosphere with high velocity anomalies is shorten gradually from the northwest to the southeast direction, and the thickness of lithosphere is about 150~200 km beneath the northwest of mid-lower Yangtze region (Fig. 1). However, the asthenosphere with low velocity anomalies characterized reversely to the lithosphere, which is consistent with other previous results. Therefore, we can propose that the upwelling of mantle material plays a primary role for the thinning of lithosphere beneath the southeast of mid-lower Yangtze region. Acknowledgment: We thank the financial support of SinoProbe by the Ministry of Finance and Ministry of Land and Resources, P. R. China, under Grant sinoprobe-03, the financial support by National Natural Science Foundation of China under Grants 40930418 and 40904021, and the financial supported by “the Fundamental Research Funds for the Central Universities” under Grant 2010ZD09. Fig. 1 (A) Epicentral locations of the 46 teleseismic events (blue squares) used in this study. The triangle denotes the center of seismic stations; (B) Locations of 38 portable seismic stations (blue squares) and the profile line of OO’ (red line); (C) Vertical cross section of P-wave velocity image by this study along the profile line of OO’. Red and blue colors represent slow and fast velocities, respectively.

Lateral Variations of the Mantle Transition Zone Structure beneath the Southeastern Tibetan Plateau Revealed by P-wave Receiver Functions

NASA Astrophysics Data System (ADS)

Bai, Y.; Ai, Y.; Jiang, M.; He, Y.; Chen, Q.

2017-12-01

The deep structure of the southeastern Tibetan plateau is of great scientific importance to a better understanding of the India-Eurasia collision as well as the evolution of the magnificent Tibetan plateau. In this study, we collected 566 permanent and temporary seismic stations deployed in SE Tibet, with a total of 77853 high quality P-wave receiver functions been extracted by maximum entropy deconvolution method. On the basis of the Common Conversion Point (CCP) stacking technique, we mapped the topography of the 410km and 660km discontinuities (hereinafter called the `410' and the `660'), and further investigated the lateral variation of the mantle transition zone (MTZ) thickness beneath this region. The background velocity model deduced from H-κ stacking results and a previous body-wave tomographic research was applied for the correction of the crustal and upper mantle heterogeneities beneath SE Tibet for CCP stacking. Our results reveal two significantly thickened MTZ anomalies aligned nearly in the south-north direction. The magnitude of both anomalies are 30km above the global average of 250km. The southern anomaly located beneath the Dianzhong sub-block and the Indo-China block is characterized by a slightly deeper `410' and a greater-than-normal `660', while the northern anomaly beneath western Sichuan has an uplifted `410' and a depressed `660'. Combining with previous studies in the adjacent region, we suggest that slab break-off may occurred during the eastward subduction of the Burma plate, with the lower part of the cold slab penetrated into the MTZ and stagnated at the bottom of the `660' which may cause the southern anomaly in our receiver function images. The origin of the Tengchong volcano is probably connected to the upwelling of the asthenospheric material caused by the slab break-off or to the ascending of the hot and wet material triggered by the dehydration of stagnant slab in the MTZ. The anomaly in the north, on the other hand, might be the consequence of the delamination of the overlying lithosphere sinking into the MTZ. This work is supported by the National Natural Science Foundation of China (grants 41474040, 41125015 and 41274002).

Natural attenuation of chlorinated volatile organic compounds in ground water at Operable Unit 1, Naval Undersea Warfare Center, Division Keyport, Washington

USGS Publications Warehouse

Dinicola, Richard S.; Cox, S.E.; Landmeyer, J.E.; Bradley, P.M.

2002-01-01

The U.S. Geological Survey (USGS) evaluated the natural attenuation of chlorinated volatile organic compounds (CVOCs) in ground water beneath the former landfill at Operable Unit 1 (OU 1), Naval Undersea Warfare Center, Division Keyport, Washington. The predominant contaminants in ground water are trichloroethene (TCE) and its degradation byproducts cis-1,2-dichloroethene (cisDCE) and vinyl chloride (VC). The Navy planted two hybrid poplar plantations on the landfill in spring of 1999 to remove and control the migration of CVOCs in shallow ground water. Previous studies provided evidence that microbial degradation processes also reduce CVOC concentrations in ground water at OU 1, so monitored natural attenuation is a potential alternative remedy if phytoremediation is ineffective. This report describes the current (2000) understanding of natural attenuation of CVOCs in ground water at OU 1 and the impacts that phytoremediation activities to date have had on attenuation processes. The evaluation is based on ground-water and surface-water chemistry data and hydrogeologic data collected at the site by the USGS and Navy contractors between 1991 and 2000. Previously unpublished data collected by the USGS during 1996-2000 are presented. Natural attenuation of CVOCs in shallow ground water at OU 1 is substantial. For 1999-2000 conditions, approximately 70 percent of the mass of dissolved chlorinated ethenes that was available to migrate from the landfill was completely degraded in shallow ground water before it could migrate to the intermediate aquifer or discharge to surface water. Attenuation of CVOC concentrations appears also to be substantial in the intermediate aquifer, but biodegradation appears to be less significant; those conclusions are less certain because of the paucity of data downgradient of the landfill beneath the tide flats. Attenuation of CVOC concentrations is also substantial in surface water as it flows through the adjacent marsh and out to the tide flats. Attenuation processes other than dilution reduce the CVOC flux in marsh surface water by about 40 percent by the time the water discharges to the tide flats. Despite the importance of natural attenuation processes at reducing both the contaminant concentrations and the contaminant mass at OU 1, natural attenuation alone was not effective enough in the year 2000 to meet current numerical remediation goals for the site. That was in part due to the relatively short distance between the landfill and the adjacent marsh, and in part due to the extremely high CVOC concentrations directly beneath the landfill. Phytoremediation activities had some apparent effect on contaminant concentrations in ground water and surface water, but ground-water redox conditions to date (2000) were not affected by the February 1999 asphalt removal for tree planting. The poplar trees in the phytoremediation plantations were not yet mature in 2000, so the lack of discernible changes to date is understandable. Concentration changes of some redox-sensitive compounds suggest that increased recharge following asphalt removal diluted ambient landfill ground water. CVOC concentrations increased in some downgradient wells in both the northern and southern plantations after asphalt removal, whereas CVOC concentrations decreased in some upgradient wells in the southern plantation. A clear increase in CVOC concentrations in marsh surface water followed asphalt removal, apparently from increased contaminant discharge in ground water beneath the southern plantation. The results of the natural attenuation evaluation suggest than minor modifications to the current sampling plan may be beneficial to understanding the future impacts of phytoremediation and natural attenuation on the fate and distribution of CVOCs at OU 1.

X-231B technology demonstration for in situ treatment of contaminated soil: Contaminant characterization and three dimensional spatial modeling

DOE Office of Scientific and Technical Information (OSTI.GOV)

West, O.R.; Siegrist, R.L.; Mitchell, T.J.

1993-11-01

Fine-textured soils and sediments contaminated by trichloroethylene (TCE) and other chlorinated organics present a serious environmental restoration challenge at US Department of Energy (DOE) sites. DOE and Martin Marietta Energy Systems, Inc. initiated a research and demonstration project at Oak Ridge National Laboratory. The goal of the project was to demonstrate a process for closure and environmental restoration of the X-231B Solid Waste Management Unit at the DOE Portsmouth Gaseous Diffusion Plant. The X-231B Unit was used from 1976 to 1983 as a land disposal site for waste oils and solvents. Silt and clay deposits beneath the unit were contaminatedmore » with volatile organic compounds and low levels of radioactive substances. The shallow groundwater was also contaminated, and some contaminants were at levels well above drinking water standards. This document begins with a summary of the subsurface physical and contaminant characteristics obtained from investigative studies conducted at the X-231B Unit prior to January 1992 (Sect. 2). This is then followed by a description of the sample collection and analysis methods used during the baseline sampling conducted in January 1992 (Sect. 3). The results of this sampling event were used to develop spatial models for VOC contaminant distribution within the X-231B Unit.« less

F-Area Acid/Caustic Basin groundwater monitoring report. Second quarter 1995

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

1995-09-01

During second quarter 1995, samples from the FAC monitoring wells at the F-Area Acid/Caustic Basin were collected and analyzed for herbicides/pesticides, indicator parameters, metals, nitrate, radionuclide indicators, volatile organic compounds, and other constituents. Piezometer FAC 5P and monitoring well FAC 6 were dry and could not be sampled. New monitoring wells FAC 9C, 10C, 11C, and 12C were completed in the Barnwell/McBean aquifer and were sampled for the first time during third quarter 1994 (second quarter 1995 is the fourth of four quarters of data required to support the closure of the basin). Analytical results that exceeded final Primary Drinkingmore » Water Standards (PDWS) or Savannah River Site (SRS) Flag 2 criteria such as the SRS turbidity standard of 50 NTU during the quarter were as follows: gross alpha exceeded the final PDWS and aluminum, iron, manganese, and radium-226 exceeded the SRS Flag 2 criteria in one or more of the FAC wells. Turbidity exceeded the SRS standard (50 NTU) in well FAC 3. Groundwater flow direction in the water table beneath the F-Area Acid/Caustic Basin was to the west at a rate of 1300 feet per year. Groundwater flow in the Barnwell/McBean was to the northeast at a rate of 50 feet per year.« less

Elastic and anelastic structure of the lowermost mantle beneath the Western Pacific from waveform inversion

NASA Astrophysics Data System (ADS)

Konishi, Kensuke; Fuji, Nobuaki; Deschamps, Frédéric

2017-03-01

We investigate the elastic and anelastic structure of the lowermost mantle at the western edge of the Pacific large low shear velocity province (LLSVP) by inverting a collection of S and ScS waveforms. The transverse component data were obtained from F-net for 31 deep earthquakes beneath Tonga and Fiji, filtered between 12.5 and 200 s. We observe a regional variation of S and ScS arrival times and amplitude ratios, according to which we divide our region of interest into three subregions. For each of these subregions, we then perform 1-D (depth-dependent) waveform inversions simultaneously for radial profiles of shear wave velocity (VS) and seismic quality factor (Q). Models for all three subregions show low VS and low Q structures from 2000 km depth down to the core-mantle boundary. We further find that VS and Q in the central subregion, sampling the Caroline plume, are substantially lower than in the surrounding regions, whatever the depth. In the central subregion, VS-anomalies with respect to PREM (dVS) and Q are about -2.5 per cent and 216 at a depth of 2850 km, and -0.6 per cent and 263 at a depth of 2000 km. By contrast, in the two other regions, dVS and Q are -2.2 per cent and 261 at a depth of 2850 km, and -0.3 per cent and 291 at a depth of 2000 km. At depths greater than ∼2500 km, these differences may indicate lateral variations in temperature of ∼100 K within the Pacific LLSVP. At shallower depths, they may be due to the temperature difference between the Caroline plume and its surroundings, and possibly to a small fraction of iron-rich material entrained by the plume.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Horn, Scott; Hanula, James, L.

Abstract This study determined if short-term removal of coarse woody debris would reduce prey available to red-cockaded woodpeckers (Picoides borealis Vieillot) and other bark-foraging birds at the Savannah River Site in Aiken and Barnwell counties, SC. All coarse woody debris was removed from four 9-ha plots of mature loblolly pine (Pinus taeda L.) in 1997 and again in 1998. We sampled arthropods in coarse woody debris removal and control stands using crawl traps that captured arthropods crawling up tree boles, burlap bands wrapped around trees, and cardboard panels placed on the ground. We captured 27 orders and 172 families ofmore » arthropods in crawl traps whereas 20 arthropod orders were observed under burlap bands and cardboard panels. The most abundant insects collected from crawl traps were aphids (Homoptera: Aphididae) and ants (Hymenoptera: Forrnicidae). The greatest biomass was in the wood cockroaches (Blattaria: Blattellidae), caterpillars (Lepidoptera) in the Family Noctuidae, and adult weevils (Coleoptera: Curculionidae). The most common group observed underneath cardboard panels was lsoptera (termites), and the most common taxon under burlap bands was wood cockroaches. Overall, arthropod abundance and biomass captured in crawl traps was similar in control and removal plots. In contrast, we observed more arthropods under burlap bands (mean & SE; 3,021.5 k 348.6, P= 0.03) and cardboard panels (3,537.25 k 432.4, P= 0.04) in plots with coarse woody debris compared with burlap bands (2325 + 171.3) and cardboard panels (2439.75 + 288.9) in plots where coarse woody debris was removed. Regression analyses showed that abundance beneath cardboard panels was positively correlated with abundance beneath burlap bands demonstrating the link between abundance on the ground with that on trees. Our results demonstrate that short-term removal of coarse woody debris from pine forests reduced overall arthropod availability to bark-foraging birds.« less

N-MORB crust beneath Fuerteventura in the easternmost part of the Canary Islands: evidence from gabbroic xenoliths

NASA Astrophysics Data System (ADS)

Neumann, Else-Ragnhild; Vannucci, Riccardo; Tiepolo, Massimo

2005-09-01

Gabbro xenoliths reported in this paper were collected in northern Fuerteventura, the Canary Island located closest to the coast of Africa. The xenoliths are very fresh and consist of Ti-Al-poor clinopyroxene + plagioclase (An87-67) + olivine (Fo72-86) ± orthopyroxene. Clinopyroxene and orthopyroxene are constantly and markedly depleted in light rare earth elements (LREE) relative to heavy REE (HREE), as expected for cumulus minerals formed from highly refractory N-MORB-type melts. In contrast, whole-rock Primordial Mantle-normalized trace element patterns range from mildly S-shaped (mildly depleted in Pr-Sm relative to both the strongly incompatible elements Rb-La and the HREE) to enriched. Estimates show that the trace element compositions of the rocks and their minerals are compatible with formation as N-MORB gabbro cumulates, which have been infiltrated at various extents (≤1% to >5%) by enriched alkali basaltic melts. The enriched material is mainly concentrated along grain boundaries and cracks through mineral grains, suggesting that the infiltration is relatively recent, and is thus associated with the Canary Islands magmatism. Our data contradict the hypothesis that a mantle plume was present in this area during the opening of the Atlantic Ocean. No evidence of continental material that might reflect attenuated continental crust in the area has been found. Gabbro xenoliths with REE and trace element compositions similar to those exhibited by the Fuerteventura gabbros are also found among gabbro xenoliths from the islands of La Palma (western Canary Islands) and Lanzarote. The compositions of the most depleted samples from these islands are closely similar, implying that there was no significant change in chemistry during the early stages of formation of the Atlantic oceanic crust in this area. Strongly depleted gabbros similar to those collected in Fuerteventura have also been retrieved in the MARK area along the central Mid-Atlantic Ridge. The presence of N-MORB oceanic crust beneath Fuerteventura implies that the continent-ocean transition in the Canary Islands area must be relatively sharp, in contrast to the situation both further north along the coast of Morocco, and along the Iberian peninsula.

Metolachlor and its metabolites in tile drain and stream runoff in the canajoharie creek watershed

USGS Publications Warehouse

Phillips, P.J.; Wall, G.R.; Thurman, E.M.; Eckhardt, D.A.; Vanhoesen, J.

1999-01-01

Water samples collected during April-November 1997 from tile drains beneath cultivated fields in central New York indicate that two metabolites of the herbicide metolachlor-metolachlor ESA (ethanesulfonic acid) and OA (oxanilic acid) can persist in agricultural soils for 4 or more years after application and that fine-grained soils favor the transport of metolachlor ESA over metolachlor and metolachlor OA. Concentrations of metolachlor ESA from the tile drains ranged from 3.27 to 23.4 ??g/L (200 1800 times higher than those of metolachlor), metolachlor OA concentrations ranged from 1.14 to 13.5 ??g/L, and metolachlor concentrations ranged from less than 0.01 to 0.1 ??g/L. In the receiving stream, concentrations of metolachlor ESA were always below 0.6 ??g/L except during a November storm, when concentrations reached 0.85 ??g/L. Concentrations of metolachlor ESA in the stream were 2 45 times higher than those of metolachlor, reflecting the greater relative concentrations of metolachlor in surface water runoff than in tile drain runoff. These results are consistent with findings in other studies that acetanilide herbicide degredates are found in much higher concentrations than parent compounds in both surface water and groundwater.Water samples collected during April-November 1997 from tile drains beneath cultivated fields in central New York indicate that two metabolites of the herbicide metolachlor-metolachlor ESA (ethanesulfonic acid) and OA (oxanilic acid)-can persist in agricultural soils for 4 or more years after application and that fine-grained soils favor the transport of metolachlor ESA over metolachlor and metolachlor OA. Concentrations of metolachlor ESA from the tile drains ranged from 3.27 to 23.4 ??g/L (200-1800 times higher than those of metolachlor), metolachlor OA concentrations ranged from 1.14 to 13.5 ??g/L, and metolachlor concentrations ranged from less than 0.01 to 0.1 ??g/L. In the receiving stream, concentrations of metolachlor ESA were always below 0.6 ??g/L except during a November storm, when concentrations reached 0.85 ??g/L. Concentrations of metolachlor ESA in the stream were 2-45 times higher than those of metolachlor, reflecting the greater relative concentrations of metolachlor in surface water runoff than in tile drain runoff. These results are consistent with findings in other studies that acetanilide herbicide degredates are found in much higher concentrations than parent compounds in both surface water and groundwater.

Factors affecting the movement and persistence of nitrate and pesticides in the surficial and upper Floridan aquifers in two agricultural areas in the southeastern United States

USGS Publications Warehouse

Katz, B.G.; Berndt, M.P.; Crandall, C.A.

2014-01-01

Differences in the degree of confinement, redox conditions, and dissolved organic carbon (DOC) are the main factors that control the persistence of nitrate and pesticides in the Upper Floridan aquifer (UFA) and overlying surficial aquifer beneath two agricultural areas in the southeastern US. Groundwater samples were collected multiple times from 66 wells during 1993–2007 in a study area in southwestern Georgia (ACFB) and from 48 wells in 1997–98 and 2007–08 in a study area in South Carolina (SANT) as part of the US Geological Survey National Water-Quality Assessment Program. In the ACFB study area, where karst features are prevalent, elevated nitrate-N concentrations in the oxic unconfined UFA (median 2.5 mg/L) were significantly (p = 0.03) higher than those in the overlying oxic surficial aquifer (median 1.5 mg/L). Concentrations of atrazine and deethylatrazine (DEA; the most frequently detected pesticide and degradate) were higher in more recent groundwater samples from the ACFB study area than in samples collected prior to 2000. Conversely, in the SANT study area, nitrate-N concentrations in the UFA were mostly <0.06 mg/L, resulting from anoxic conditions and elevated DOC concentrations that favored denitrification. Although most parts of the partially confined UFA in the SANT study area were anoxic or had mixed redox conditions, water from 28 % of the sampled wells was oxic and had low DOC concentrations. Based on the groundwater age information, nitrate concentrations reflect historic fertilizer N usage in both the study areas, but with a lag time of about 15–20 years. Simulated responses to future management scenarios of fertilizer N inputs indicated that elevated nitrate-N concentrations would likely persist in oxic parts of the surficial aquifer and UFA for decades even with substantial decreases in fertilizer N inputs over the next 40 years.

Dieldrin-induced mortality in an endangered species, the gray bat (Myotis grisescens)

USGS Publications Warehouse

Clark, D.R.; LaVal, R.K.; Swineford, D.M.

1978-01-01

Brains of juvenile gray bats, Myotis grisescens, found dead beneath maternity roosts in two Missouri caves contained lethal concentrations of dieldrin. One colony appeared to be abnormally small, and more dead bats were found a year after the juvenile bats had been collected. This is the first report to link the field mortality of bats directly to insecticide residues acquired through the food chain.

Chemical quality of depositional sediments and associated soils in New Orleans and the Louisiana peninsula following Hurricane Katrina

USGS Publications Warehouse

Adams, C.; Witt, E.C.; Wang, Jingyuan; Shaver, D.K.; Summers, D.; Filali-Meknassi, Y.; Shi, H.; Luna, R.; Anderson, N.

2007-01-01

Hurricane Katrina made landfall on the Louisiana peninsula south of New Orleans on Aug 29, 2005. The resulting storm surge caused numerous levy breaches in the parishes of New Orleans as well as on the Louisiana peninsula. This study was conducted to determine the concentrations of inorganic and organic constituents in sediments and associated soils in New Orleans parishes and the Louisiana peninsula after the floodwaters had been removed and/or receded following Hurricane Katrina. A total of 46 sediment and soil samples were analyzed that were collected throughout New Orleans and the Louisiana peninsula. Approximately 20% of the sediment samples were analyzed, including shallow sediment samples from locations that included the top and beneath automobiles, in residential and commercial areas, and near refineries. Gasoline constituents, pesticides, and leachable heavy metals were analyzed using headspace gas chromatography/mass spectrometry (GC/MS), organic extraction GC/MS, and inductively coupled plasma/mass spectrometry, respectively. A significant number of samples had leachable As and Pb concentrations in excess of drinking water standards. The remaining metals analyzed (i.e., Cd, Cr, Cu, Hg, and V) generally had much lower leachable levels. Of the gasoline constituents, only benzene was observed above the limit of detection (of 5 ??g/kg), with no samples observed as being above the method detection limits of 10 ??g/kg. For the 18 pesticides analyzed, most were in the nondetectable range and all were in trace amounts that were orders of magnitude below regulatory guidelines. ?? 2007 American Chemical Society.

Reconnaissance studies of potential petroleum source rocks in the Middle Jurassic Tuxedni Group near Red Glacier, eastern slope of Iliamna Volcano

USGS Publications Warehouse

Stanley, Richard G.; Herriott, Trystan M.; LePain, David L.; Helmold, Kenneth P.; Peterson, C. Shaun

2013-01-01

Previous geological and organic geochemical studies have concluded that organic-rich marine shale in the Middle Jurassic Tuxedni Group is the principal source rock of oil and associated gas in Cook Inlet (Magoon and Anders, 1992; Magoon, 1994; Lillis and Stanley, 2011; LePain and others, 2012; LePain and others, submitted). During May 2009 helicopter-assisted field studies, 19 samples of dark-colored, fine-grained rocks were collected from exposures of the Red Glacier Formation of the Tuxedni Group near Red Glacier, about 70 km west of Ninilchik on the eastern flank of Iliamna Volcano (figs. 1 and 3). The rock samples were submitted to a commercial laboratory for analysis by Rock-Eval pyrolysis and to the U.S. Geological Survey organic geochemical laboratory in Denver, Colorado, for analysis of vitrinite reflectance. The results show that values of vitrinite reflectance (percent Ro) in our samples average about 2 percent, much higher than the oil window range of 0.6–1.3 percent (Johnsson and others, 1993). The high vitrinite reflectance values indicate that the rock samples experienced significant heating and furthermore suggest that these rocks may have generated oil and gas in the past but no longer have any hydrocarbon source potential. The high thermal maturity of the rock samples may have resulted from (1) the thermaleffects of igneous activity (including intrusion by igneous rocks), (2) deep burial beneath Jurassic, Cretaceous, and Tertiary strata that were subsequently removed by uplift and erosion, or (3) the combined effects of igneous activity and burial.

Saltwater movement in the upper Floridan aquifer beneath Port Royal Sound, South Carolina

USGS Publications Warehouse

Smith, Barry S.

1994-01-01

Freshwater for Hilton Head Island, South Carolina, is supplied by withdrawals from the Upper Floridan aquifer. Freshwater for the nearby city of Savannah, Georgia, and for the industry that has grown adjacent to the city, has also been supplied, in part, by withdrawal from the Upper Floridan aquifer since 1885. The withdrawal of ground water has caused water levels in the Upper Floridan aquifer to decline over a broad area, forming a cone of depression in the potentiometric surface of the aquifer centered near Savannah. In 1984, the cone of depression extended beneath Hilton Head Island as far as Port Royal Sound. Flow in the aquifer, which had previously been toward Port Royal Sound, has been reversed, and, as a result, saltwater in the aquifer beneath Port Royal Sound has begun to move toward Hilton Head Island. The Saturated-Unsaturated Transport (SUTRA) model of the U.S. Geological Survey was used for the simulation of density-dependent ground-water flow and solute transport for a vertical section of the Upper Floridan aquifer and upper confining unit beneath Hilton Head Island and Port Royal Sound. The model simulated a dynamic equilibrium between the flow of seawater and freshwater in the aquifer near the Gyben-Herzberg position estimated for the period before withdrawals began in 1885; it simulated reasonable movements of brackish water and saltwater from that position to the position determined by chemical analyses of samples withdrawn from the aquifer in 1984, and it approximated hydraulic heads measured in the aquifer in 1976 and 1984. The solute-transport simulations indicate that the transition zone would continue to move toward Hilton Head Island even if pumping ceased on the island. Increases in existing withdrawals or additional withdrawals on or near Hilton Head Island would accelerate movement of the transition zone toward the island, but reduction in withdrawals or the injection of freshwater would slow movement toward the island, according to the simulations. Future movements of the transition zone toward Hilton Head Island will depend on hydraulic gradients in the aquifer beneath the island and the sound. Hydraulic gradients in the Upper Floridan aquifer beneath Hilton Head Island and Port Royal Sound are strongly influenced by withdrawals on the island and near Savannah. Since 1984, withdrawals on Hilton Head Island have increased.

Understanding the nature of mantle upwelling beneath East-Africa

NASA Astrophysics Data System (ADS)

Civiero, Chiara; Hammond, James; Goes, Saskia; Ahmed, Abdulhakim; Ayele, Atalay; Doubre, Cecile; Goitom, Berhe; Keir, Derek; Kendall, Mike; Leroy, Sylvie; Ogubazghi, Ghebrebrhan; Rumpker, Georg; Stuart, Graham

2014-05-01

The concept of hot upwelling material - otherwise known as mantle plumes - has long been accepted as a possible mechanism to explain hotspots occurring at Earth's surface and it is recognized as a way of removing heat from the deep Earth. Nevertheless, this theory remains controversial since no one has definitively imaged a plume and over the last decades several other potential mechanisms that do not require a deep mantle source have been invoked to explain this phenomenon, for example small-scale convection at rifted margins, meteorite impacts or lithospheric delamination. One of the best locations to study the potential connection between hotspot volcanism at the surface and deep mantle plumes on land is the East African Rift (EAR). We image seismic velocity structure of the mantle below EAR with higher resolution than has been available to date by including seismic data recorded by stations from many regional networks ranging from Saudi Arabia to Tanzania. We use relative travel-time tomography to produce P- velocity models from the surface down into the lower mantle incorporating 9250 ray-paths in our model from 495 events and 402 stations. We add smaller earthquakes (4.5 < mb < 5.5) from poorly sampled regions in order to have a more uniform data coverage. The tomographic results allow us to image structures of ~ 100-km length scales to ~ 1000 km depth beneath the northern East-Africa rift (Ethiopia, Eritrea, Djibouti, Yemen) with good resolution also in the transition zone and uppermost lower mantle. Our observations provide evidence that the shallow mantle slow seismic velocities continue trough the transition zone and into the lower mantle. In particular, the relatively slow velocity anomaly beneath the Afar Depression extends up to depths of at least 1000 km depth while another low-velocity anomaly beneath the Main Ethiopian Rift seems to be present in the upper mantle only. These features in the lower mantle are isolated with a diameter of about 400 km indicating deep multiple sources of upwelling that converge in broader low-velocity bodies along the rift axis at shallow depths. Moreover, our preliminary models show that the low-velocity feature in the transition zone and uppermost lower mantle beneath Afar trends to the northeast beneath the Red Sea and Saudi Arabia as opposed to being linked to the African Superplume towards the southwest.

Evidence for shallow dehydration of the subducting plate beneath the Mariana forearc: New insights into the water cycle at subduction zones

NASA Astrophysics Data System (ADS)

Ribeiro, J.; Stern, R. J.; Kelley, K. A.; Shaw, A. M.; Martinez, F.; Ohara, Y.

2014-12-01

Water is efficiently recycled at subduction zones. It is fluxed from the surface into the mantle by the subducted plate and back to the surface or crust through explosive arc volcanism and degassing. Fluids released from dehydrating the subducting plate are transfer agents of water. Geophysical modeling [1] and the geochemistry of arc glasses [2] suggest that at cold-slab subduction zones, such as the Mariana convergent margin, the downgoing plate mostly dehydrates beneath the volcanic arc front (≥ ~ 80 -100 km depth to slab) to trigger volcanism. However, there is a gap in our understanding of the water fluxes released beneath forearcs, as examples of forearc magmatism are extremely rare. Here, we investigate the Southernmost Mariana Forearc Rift (SEMFR), where MORB-like spreading occurred unusually close to the trench, sampling slab-derived aqueous fluids released at ~ 30 to 100 km depth from the subducted plate. Examining the trace element and water contents of olivine-hosted melt inclusions and glassy rinds from the young (2 - 4 Ma) and fresh SEMFR pillowed basalts provide new insights into the global water cycle. SEMFR lavas contain ~2 wt % H2O, and the olivine-hosted melt inclusions have the highest subduction-related H2O/Ce ratios (H2O/Ce = 6000 - 19000) ever recorded in arc magmas (H2O/Ce < 10600 and global averaged H2O/Ce < 3000). Our findings show that (i) slab-derived fluids released beneath forearcs are water-rich compared to the deeper fluids released beneath the arc system; and (ii) cold downgoing plates lose most of their water at shallow depths (~ 70 - 80 km slab depth), suggesting that water is efficiently recycled beneath the forearc (≥ 90%). 1. Van Keken, P.E., et al., Subduction factory: 4. Depth-dependent flux of H2O from subducting slabs worldwide. Journal of Geophysical Research: Solid Earth, 2011. 116(B1): p. B01401, DOI: 10.1029/2010jb007922. 2. Ruscitto, D.M., et al., Global variations in H2O/Ce: 2. Relationships to arc magma geochemistry and volatile fluxes. Geochemistry Geophysics Geosystems, 2012. 13(3): p. Q03025, DOI: 10.1029/2011gc003887.

Fingerprinting TCE in a bedrock aquifer using compound-specific isotope analysis.

PubMed

Lojkasek-Lima, Paulo; Aravena, Ramon; Parker, Beth L; Cherry, John A

2012-01-01

A dual isotope approach based on compound-specific isotope analysis (CSIA) of carbon (C) and chlorine (Cl) was used to identify sources of persistent trichloroethylene (TCE) that caused the shut-down in 1994 of a municipal well in an extensive fractured dolostone aquifer beneath Guelph, Ontario. Several nearby industrial properties have known subsurface TCE contamination; however, only one has created a comprehensive monitoring network in the bedrock. The impacted municipal well and many monitoring wells were sampled for volatile organic compounds (VOCs), inorganic parameters, and CSIA. A wide range in isotope values was observed at the study site. The TCE varies between -35.6‰ and -21.8‰ and from 1.6‰ to 3.2‰ for δ(13) C and δ(37) Cl, respectively. In case of cis-1,2-dichloroethene, the isotope values range between -36.3‰ and -18.9‰ and from 2.4‰ to 4.7‰ for δ(13) C and δ(37) Cl, respectively. The dual isotope approach represented by a plot of δ(13) C vs. δ(37) Cl shows the municipal well samples grouped in a domain clearly separate from all other samples from the property with the comprehensive well network. The CSIA results collected under non-pumping and short-term pumping conditions thus indicate that this particular property, which has been studied intensively for several years, is not a substantial contributor of the TCE presently in the municipal well under non-pumping conditions. This case study demonstrates that CSIA signatures would have been useful much earlier in the quest to examine sources of the TCE in the municipal well if bedrock monitoring wells had been located at several depths beneath each of the potential TCE-contributing properties. Moreover, the CSIA results show that microbial reductive dechlorination of TCE occurs in some parts of the bedrock aquifer. At this site, the use of CSIA for C and Cl in combination with analyses of VOC and redox parameters proved to be important due to the complexity introduced by biodegradation in the complex fractured rock aquifer. It is highly recommended to revisit the study when the municipal well is back into full operation. © 2012, The Author(s). Ground Water © 2012, National Ground Water Association.

Mantle plumes and associated flow beneath Arabia and East Africa

NASA Astrophysics Data System (ADS)

Chang, Sung-Joon; Van der Lee, Suzan

2011-02-01

We investigate mantle plumes and associated flow beneath the lithosphere by imaging the three-dimensional S-velocity structure beneath Arabia and East Africa. This image shows elongated vertical and horizontal low-velocity anomalies down to at least mid mantle depths. This three-dimensional S-velocity model is obtained through the joint inversion of teleseismic S- and SKS-arrival times, regional S- and Rayleigh waveform fits, fundamental-mode Rayleigh-wave group velocities, and independent Moho constraints from receiver functions, reflection/refraction profiles, and gravity measurements. In the resolved parts of our S-velocity model we find that the Afar plume is distinctly separate from the Kenya plume, showing the Afar plume's origin in the lower mantle beneath southwestern Arabia. We identify another quasi-vertical low-velocity anomaly beneath Jordan and northern Arabia which extends into the lower mantle and may be related to volcanism in Jordan, northern Arabia, and possibly southern Turkey. Comparing locations of mantle plumes from the joint inversion with fast axes of shear-wave splitting, we confirm horizontal mantle flow radially away from Afar. Low-velocity channels in our model support southwestward flow beneath Ethiopia, eastward flow beneath the Gulf of Aden, but not northwestwards beneath the entire Red Sea. Instead, northward mantle flow from Afar appears to be channeled beneath Arabia.

Persistence and efficacy of termiticides used in preconstruction treatments to soil in Mississippi

Treesearch

J.E. Mulrooney; M.K. Davis; T.L. Wagner; R.L. Ingram

2006-01-01

Laboratory and field studies were conducted to determine the persistence and efficacy of termiticides used as preconstruction treatments against subterranean termites. Bifenthrin (0.067%), chlorpyrifos (0.75%), and imidacloprid (0.05%) ( [AI]; wt:wt) were applied to soil beneath a monolithic concrete slab at their minimum labeled rates. Soil samples were taken from...

Reflections Beneath the Surface: We Are More than You See.

ERIC Educational Resources Information Center

Bass, Bruce; And Others

This volume is a sampling of 18 pieces of writing by students in a workplace education writing course called Advanced Writing. It contains the following poems, fiction, and nonfiction written in and outside of class: "Artist" (Bruce Bass); "Tuesday Morning" (Kathy Colon); "House" (Lee Christian); "Life" (Alice Chapin); "A Cat Story" (Jane E.…

Os and HSE of the hot upper mantle beneath southern Tibet: Indian mantle affinity?

NASA Astrophysics Data System (ADS)

Zhao, Z.; Dale, C. W.; Pearson, D. G.; Niu, Y.; Zhu, D.; Mo, X.

2011-12-01

The subduction of the Indian plate (including cratonic continental crust and/or upper mantle) beneath southern Tibet is widely accepted from both geological and geophysical studies. Mantle-derived xenoliths from this region provide a means of directly investigating the mantle underlying the southern part of the plateau. Studies of xenoliths hosted in the Sailipu ultrapotassic volcanic rocks, erupted at ~17 Ma, have indicated that the subcontinental mantle of southern Tibetan Plateau is hot and strongly influenced by metasomatism (Zhao et al., 2008a, b; Liu et al., 2011). Here we report comprehensive EPMA and LA-ICP-MS major and trace element data for the Sailipu xenoliths and also whole rock Os isotope and HSE data in order to constrain the depletion history of the mantle and to identify the presence of any potential Indian cratonic mantle. The xenoliths, ranging in size from 0.5cm to 1.5cm in diameter, are mostly peridotites. The calculated temperatures are 1010-1230°C at the given pressures of ~1.6-2.0 GPa (n=47). These P-T conditions are similar to rift-related upper mantle regimes (e.g. Kenya), indicating the influence of regional extension beneath southern Tibet in the Miocene. A series of compositional discriminations for minerals (Cpx, Opx, Ol, and Phl), e.g. Fo<90, suggest that the xenoliths are non-cratonic spinel-peridotite (cratonic peridotite olivine Fo> ~91), with a clear metasomatic signature We obtained Os isotope data and abundances of highly siderophile elements (HSE, including Os, Ir, Ru, Pt, Pd and Re) on a set of six olivine-dominated peridotite samples from Sailipu volcanics, less than 1 cm in dimension. They allow us to further constrain the nature and state of the upper mantle beneath the southern Tibet. Sailipu samples display low total HSE abundances (Os+Ir+Ru+Pt+Pd+Re) ranging from 8.7 to 25 ppb, with nearly constant Os, Ir , and Ru, but rather varied Pt (2-13), Pd (0.4-5.2), and Re (0.01-0.5). Chondrite-normalised Pd/Ir ratios range from 0.2 to 2.4 reflecting significant metasomatism of some samples. The xenoliths exhibit 187Os/188Os ratios of 0.12213-0.12696, corresponding to γOs ranging from -4.2 to -0.4 - much higher than ancient cratonic mantle. Thus, on the basis of mineral chemistry and whole rock Os isotopes, Indian cratonic mantle is absent from our suite of xenoliths. Therefore, assuming the presence of cratonic mantle, it seems likely that the xenoliths do not sample the deep basal section of the lithosphere where cratonic Indian lithosphere is thought to be present under southern Tibet. In which case, testing of the seismic and tectonic models may not be possible without garnet-facies peridotites. More work need to be done to further reveal the mantle compostion and mantle dynamics beneath Tibet. [Financially supported by the National Key Project for Basic Research of China (Project 2011CB403102 and 2009CB421002)]. [1] Zhao Z, et al., 2008a. Acta Petrologica Sinica, 24 (2): 193-202 [2] Zhao Z, et al., 2008b. Geochimica et Cosmochimica Acta, 72, 12 (Supp.): A1095 [3] Liu C-Z, et al., 2011, Geology, in press

Soil C and N patterns in a semiarid piñon-juniper woodland: Topography of slope and ephemeral channels add to canopy-intercanopy heterogeneity

USGS Publications Warehouse

Law, Darin J.; Breshears, David D.; Ebinger, Michael H.; Meyer, Clifton W.; Allen, Craig D.

2012-01-01

Carbon and nitrogen are crucial to semiarid woodlands, determining decomposition, production and redistribution of water and nutrients. Carbon and nitrogen are often greater beneath canopies than intercanopies. Upslope vs. downslope position and ephemeral channels might also cause variation in C and N. Yet, few studies have simultaneously evaluated spatial variation associated with canopy–intercanopy patches and topography. We estimated C and N upslope and downslope in an eroding piñon–juniper woodland for canopies beneath piñons (Pinus edulis) and junipers, (Juniperus monosperma), intercanopies, and ephemeral channels. Soil C and N in the surface and profile beneath canopies exceeded that of intercanopies and channels. Relative to intercanopies, channels had more profile C upslope but less downslope (profile N was not significant). Relative to upslope, profile C downslope for intercanopies was greater and for channels was less (profile N was not significant). Relative to profile, surface soil C and N exhibited less heterogeneity. Although some topographic heterogeneity was detected, results did not collectively support our redistribution hypotheses, and we are unable to distinguish if this heterogeneity is due to in situ or redistribution effects. Nonetheless, results highlight finer topographical spatial variation in addition to predominant canopy and intercanopy variation that is applicable for semiarid woodland management.

Effects of groundwater-flow paths on nitrate concentrations across two riparian forest corridors

USGS Publications Warehouse

Speiran, Gary K.

2010-01-01

Groundwater levels, apparent age, and chemistry from field sites and groundwater-flow modeling of hypothetical aquifers collectively indicate that groundwater-flow paths contribute to differences in nitrate concentrations across riparian corridors. At sites in Virginia (one coastal and one Piedmont), lowland forested wetlands separate upland fields from nearby surface waters (an estuary and a stream). At the coastal site, nitrate concentrations near the water table decreased from more than 10 mg/L beneath fields to 2 mg/L beneath a riparian forest buffer because recharge through the buffer forced water with concentrations greater than 5 mg/L to flow deeper beneath the buffer. Diurnal changes in groundwater levels up to 0.25 meters at the coastal site reflect flow from the water table into unsaturated soil where roots remove water and nitrate dissolved in it. Decreases in aquifer thickness caused by declines in the water table and decreases in horizontal hydraulic gradients from the uplands to the wetlands indicate that more than 95% of the groundwater discharged to the wetlands. Such discharge through organic soil can reduce nitrate concentrations by denitrification. Model simulations are consistent with field results, showing downward flow approaching toe slopes and surface waters to which groundwater discharges. These effects show the importance of buffer placement over use of fixed-width, streamside buffers to control nitrate concentrations.

Using helicopter TEM to delineate fresh water and salt water zones in the aquifer beneath the Okavango Delta, Botswana

NASA Astrophysics Data System (ADS)

Podgorski, Joel E.; Kinzelbach, Wolfgang K. H.; Kgotlhang, Lesego

2017-09-01

The Okavango Delta is a vast wetland wilderness in the middle of the Kalahari Desert of Botswana. It is a largely closed hydrological system with most water leaving the delta by evapotranspiration. In spite of this, the channels and swamps of the delta remain surprisingly low in salinity. To help understand the hydrological processes at work, we reanalyzed a previous inversion of data collected from a helicopter transient electromagnetic (HTEM) survey of the entire delta and performed an inversion of a high resolution dataset recorded during the same survey. Our results show widespread infiltration of fresh water to as much as ∼200 m depth into the regional saline aquifer. Beneath the western delta, freshwater infiltration extends to only about 80 m depth. Hydrological modeling with SEAWAT confirms that this may be due to rebound of the regional saltwater-freshwater interface following the cessation of surface flooding over this part of the delta in the 1880s. Our resistivity models also provide evidence for active and inactive saltwater fingers to as much as ∼100 m beneath islands. These results demonstrate the great extent of freshwater infiltration across the delta and also show that all vegetated areas along the delta's channels and swamps are potential locations for transferring solutes from surface water to an aquifer at depth.

Biomechanical factors related to occlusal load transfer in removable complete dentures.

PubMed

Żmudzki, Jarosław; Chladek, Grzegorz; Kasperski, Jacek

2015-08-01

Owing to economic conditions, removable dentures remain popular despite the discomfort and reduced chewing efficiency experienced by most denture wearers. However, there is little evidence to confirm that the level of mucosal load exceeds the pressure pain threshold. This discrepancy stimulated us to review the current state of knowledge on the biomechanics of mastication with complete removable dentures. The loading beneath dentures was analyzed in the context of denture foundation characteristics, salivary lubrication, occlusal forces, and the biomechanics of mastication. The analysis revealed that the interpretation of data collected in vivo is hindered due to the simultaneous overlapping effects of many variables. In turn, problems with determining the pressure beneath a denture and analyzing frictional processes constitute principal limitations of in vitro model studies. Predefined conditions of finite element method simulations should include the effects of oblique mastication forces, simultaneous detachment and sliding of the denture on its foundation, and the stabilizing role of balancing contacts. This review establishes that previous investigations may have failed because of their unsubstantiated assumption that, in a well-working balanced occlusion, force is only exerted perpendicular to the occlusal plane, allowing the denture to sit firmly on its foundation. Recent improvements in the simulation of realistic biomechanical denture behavior raise the possibility of assessing the effects of denture design on the pressures and slides beneath the denture.

Pn wave velocities beneath the Tanzania Craton and adjacent rifted mobile belts, east Africa

NASA Astrophysics Data System (ADS)

Brazier, Richard A.; Nyblade, Andrew A.; Langston, Charles A.; Owens, Thomas J.

2000-08-01

P wave travel times from regional earthquakes recorded by the Tanzania Broadband Seismic Experiment have been inverted for long wavelength (>100 km) Pn velocity variations beneath Tanzania using a generalized inverse algorithm. Pn velocities, on average, are 8.40 to 8.45 km/s beneath the center of the Tanzania Craton, 8.30-8.35 km/s beneath the terminus of the Eastern Branch of the rift system, and 8.35-8.40 km/s beneath the Western Branch. These velocities indicate that there are no broad (>100 km wide) thermal anomalies in the uppermost mantle beneath areas of rifting in Tanzania, and suggest that thermal anomalies present deeper in the mantle have not yet reached the base of the crust.

Ground-water quality and geochemistry, Carson Desert, western Nevada

USGS Publications Warehouse

Lico, Michael S.; Seiler, R.L.

1994-01-01

Aquifers in the Carson Desert are the primary source of drinking water, which is highly variable in chemical composition. In the shallow basin-fill aquifers, water chemistyr varies from a dilute calcium bicarbonate-dominated water beneath the irrigated areas to a saline sodium chloride- dominated water beneath unirrigated areas. Water samples from the shallow aquifers commonly have dissolved solids, chloride, magnesium, sulfate, arsenic, and manganese concentrations that exceed State of Nevada drinking-water standards. Water in the intermediante basin-fill aquifers is a dilute sodium bicarbonate type in the Fallon area and a distinctly more saline sodium chloride type in the Soda Lake-Upsal Hogback area. Dissolved solids, chloride, arsenic, fluoride, and manganese concen- trations commonly exceed drinking-water standards. The basalt aquifer contains a dilute sodium bicarbonate chloride water. Arsenic concentrations exceed standards in all sampled wells. The concen- trations of major constituents in ground water beneath the southern Carson Desert are the result of evapotranspiration and natural geochemical reactions with minerals derived mostly from igneous rocks. Water with higher concentrations of iron and manganese is near thermodynamic equilibrium with siderite and rhodochrosite and indicates that these elements may be limited by the solubility of their respective carbonate minerals. Naturally occurring radionuclides (uranium and radon-222) are present in ground water from the Carson Desert in concen- tratons higher than proposed drinking-water standards. High uranium concentrations in the shallow aquifers may be caused by evaporative concentration and the release of uranium during dissolution of iron and manganese oxides or the oxidation of sedimentary organic matter that typically has elevated uranium concentrations. Ground water in the Carson Desert does not appear to have be contaminated by synthetic organic chemicals.

Exploration of amino acid biomarkers in polar ice with the Mars Organic Analyzer

NASA Astrophysics Data System (ADS)

Jayarajah, C.; Botta, O.; Aubrey, A.; Parker, E.; Bada, J.; Mathies, R.

2009-05-01

A portable microfabricated capillary electrophoresis (CE) system named the Mars Organic Analyzer (MOA) has been developed to analyze fluorescently-labeled biomarkers including amino acids, amines, nucleobases, and amino sugars with the goal of life detection on Mars (1,2). This technology has also been shown to be effective in screening the formation of biogenic amines during fermentation (3). The MOA is a part of the Urey instrument package that has been selected for the 2016 European ExoMars mission by ESA. The identification of recent gully erosion sites, observations of ice on and beneath the surface of Mars, and the discovery of large reservoirs of sub-surface ice on Mars point to water-ice as an important target for astrobiological analyses. In addition, the ice samples on the Moon, Mercury, Europa and Enceladus are of interest due to the possibility that they may contain information on biogenic material relevant to the evolution of life. We explore here the use of the MOA instrument for the analysis of amino acids in polar ice samples. The amino acids valine, alanine/serine, glycine, glutamic acid, and aspartic acid were found in the parts-per-billion range from Greenland ice-core samples. Chiral analysis of these samples yielded D/L ratios of 0.51/0.09 for alanine/serine and 0.14/0.06 for aspartic acid. Individual amino acids in the parts-per-trillion range were found in Antarctic ice samples collected from the surface of a meteorite collection area. The distinct amino acid and amine content of these samples indicates that further biomarker characterization of ice samples as a function of sampling location, depth, and structural features will be highly informative. The rapid sensitive analysis capabilities demonstrated here establish the feasibility of using the MOA to analyze the biomarker content of ice samples in planetary exploration. 1. Skelley, A. M.; Scherer, J. R.; Aubrey, A. D.; Grover, W. H.; Ivester, R. H. C., Ehrenfreund, P.; Grunthaner, F. J.; Bada, J. L.; Mathies, R. A. PNAS, 2005, 192, 1041. 2. Skelley, A. M., Cleaves, H. J., Jayarajah, C. N., Bada, J. L. and Mathies, R. A., Astrobiology 2006, 6, 824. 3. Jayarajah, C.N., Skelley, A.M., Fortner, A.D., and Mathies, R.A., Anal. Chem. 2007, 79, 21, 8162.

Clean, Logistically Light Access to Explore the Closest Places on Earth to Europa and Enceladus

NASA Astrophysics Data System (ADS)

Winebrenner, D. P.; Elam, W. T.; Kintner, P. M. S.; Tyler, S.; Selker, J. S.

2016-12-01

At present, the logistical costs of ice drilling to depths of kilometers severely limit sampling and measurements beneath ice sheets. Thus only a tiny fraction of the 400 known subglacial lakes beneath the Antarctic Ice Sheet can ever be sampled by drilling, and study of large lakes may be limited to observations at one or, at best, a few sites. Antarctic lakes are likely highly diverse in their geochemical and geothermal fluxes, the timing and duration of their glaciations, and other characteristics. They constitute a remarkable collection of natural laboratories for learning biogeochemistries and adaptations of subglacial life on Earth. Moreover, they are arguably Earth-analogs to ice-covered seas on Europa and Enceladus, closer not only in relative terms than other analogs, but also usefully close in absolute terms for learning solar-system-wide features of ice-covered seas. It is therefore essential to sample Antarctic lakes with enough range and density, in space and time, to gain better understanding of their workings than drilling alone can provide. The logistics of thermal melt probes makes them attractive, provided that key limitations can be overcome. In particular, melt probes from the 1960s through the 1990s were unreliable, all halted in their descents by electrical failures at high voltages (which are necessary for efficient power use). Moreover, the hole above a classical melt probe refreezes, so neither samples nor the probe itself can be recovered. Here we report progress in overcoming both of these limitations with modern materials and components for reliable high-voltage operation. We have demonstrated in Greenland a 6.5 cm-diameter melt probe operating at 1050V/2.15 kW (electrical) that descended at 2.4 m/hr to 80 m depth in 2013, and after restarting in 2014, to 400 m depth, where we turned it off. We also operated a probe at 2000V/4.5 kW in 2014, which descended at 6.6 m/hr (according to a validated engineering model). These results are the second greatest depth and greatest speed attained by melt probes. We also report on testing a way to avoid complete refreezing of a melt hole, which enables cable deployment from the surface and thus small probes to reach and be recovered from great depth, as well as Raman Distributed Temperature Sensing of ice sheet temperatures, with several applications.

Interception loss, throughfall and stemflow in a maritime pine stand. I. Variability of throughfall and stemflow beneath the pine canopy

NASA Astrophysics Data System (ADS)

Loustau, D.; Berbigier, P.; Granier, A.; Moussa, F. El Hadj

1992-10-01

Patterns of spatial variability of throughfall and stemflow were determined in a maritime pine ( Pinus pinaster Ait.) stand for two consecutive years. Data were obtained from 52 fixed rain gauges and 12 stemflow measuring devices located in a 50m × 50m plot at the centre of an 18-year-old stand. The pine trees had been sown in rows 4m apart and had reached an average height of 12.6m. The spatial distribution of stems had a negligible effect on the throughfall partitioning beneath the canopy. Variograms of throughfall computed for a sample of storms did not reveal any spatial autocorrelation of throughfall for the sampling design used. Differences in throughfall, in relation to the distance from the rows, were not consistently significant. In addition, the distance from the tree stem did not influence the amount of throughfall. The confidence interval on the amount of throughfall per storm was between 3 and 8%. The stemflow was highly variable between trees. The effect of individual trees on stemflow was significant but the amount of stemflow per tree was not related to tree size (i.e. height, trunk diameter, etc.). The cumulative sampling errors on stemflow and throughfall for a single storm created a confidence interval of between ±7 and ±51% on interception. This resulted mainly from the low interception rate and sampling error on throughfall.

Ground-water flow and quality beneath sewage-sludge lagoons, and a comparison with the ground-water quality beneath a sludge-amended landfill, Marion County, Indiana

USGS Publications Warehouse

Bobay, K.E.

1988-01-01

The groundwater beneath eight sewage sludge lagoons, was studied to characterize the flow regime and to determine whether leachate had infiltrated into the glacio-fluvial sediments. Groundwater quality beneath the lagoons was compared with the groundwater quality beneath a landfill where sludge had been applied. The lagoons and landfills overlie outwash sand and gravel deposits separated by discontinuous clay layers. Shallow groundwater flows away from the lagoons and discharges into the White River. Deep groundwater discharges to the White River and flows southwest beneath Eagle Creek. After an accumulation of at least 2 inches of precipitation during 1 week, groundwater flow is temporarily reversed in the shallow aquifer, and all deep flow is along a relatively steep hydraulic gradient to the southwest. The groundwater is predominantly a calcium bicarbonate type, although ammonium accounts for more than 30% of the total cations in water from three wells. Concentrations of sodium, chloride, sulfate, iron, arsenic, boron, chemical oxygen demand, total dissolved solids, and methylene-blue-active substances indicate the presence of leachate in the groundwater. Concentrations of cadmium, chromium, copper, lead, mercury, nickel, selenium, and zinc were less than detection limits. The concentrations of 16 of 19 constituents or properties of groundwater beneath the lagoons are statistically different than groundwater beneath the landfill at the 0.05 level of significance. Only pH and concentrations of dissolved oxygen and bromide are higher in groundwater beneath the landfill than beneath the lagoons. 

Seismic Discontinuities beneath the Southwestern United States from S Receiver Functions

NASA Astrophysics Data System (ADS)

Akanbi, O. E.; Li, A.

2015-12-01

S- Receiver functions along the Colorado Plateau-Rio Grande Rift-Great Plains Transect known as La RISTRA in the southwestern United States have been utilized to map the Moho and lithosphere-asthenosphere boundary (LAB) beneath this tectonically active region. The receiver functions were stacked according to ray piercing points with moveout corrections in order to improve the signal-to-noise ratio of converted S-to-P phases. The Moho appears at 30-40 km beneath the Rio Grande Rift (RGR) and deepens to 35-45 km beneath the Great Plains (GP) and the Colorado Plateau (CP). A sharp discontinuity is observed along the profile with the average depth of 80 km beneath the RGR, 100 km beneath the GP, and 160 km beneath the CP. This discontinuity is consistent with the top of a low velocity zone in a shear wave model beneath the array and is interpreted as the LAB. Strong phases imaged at ~90 km beneath the CP and GP could be a combination of side-lobes of the Moho conversions and primary Sp phases from a mid-lithosphere discontinuity (MLD). The relatively shallow Moho and LAB beneath the Rio Grande Rift is indicative of lithosphere extension and asthenosphere upwarp. In addition, the LAB shows depth-step depressions at the RGR-CP and RGR-GP boundaries, providing evidence for mantle downwelling. The variation of the lithospheric depth across the RISTRA array supports that edge-driven, small-scale mantle convection is largely responsible for the recent extension and uplift in the Rio Grande Rift and the Colorado Plateau.

Slab melting beneath the Cascade Arc driven by dehydration of altered oceanic peridotite

NASA Astrophysics Data System (ADS)

Walowski, K. J.; Wallace, P. J.; Hauri, E. H.; Wada, I.; Clynne, M. A.

2015-05-01

Water is returned to Earth’s interior at subduction zones. However, the processes and pathways by which water leaves the subducting plate and causes melting beneath volcanic arcs are complex; the source of the water--subducting sediment, altered oceanic crust, or hydrated mantle in the downgoing plate--is debated; and the role of slab temperature is unclear. Here we analyse the hydrogen-isotope and trace-element signature of melt inclusions in ash samples from the Cascade Arc, where young, hot lithosphere subducts. Comparing these data with published analyses, we find that fluids in the Cascade magmas are sourced from deeper parts of the subducting slab--hydrated mantle peridotite in the slab interior--compared with fluids in magmas from the Marianas Arc, where older, colder lithosphere subducts. We use geodynamic modelling to show that, in the hotter subduction zone, the upper crust of the subducting slab rapidly dehydrates at shallow depths. With continued subduction, fluids released from the deeper plate interior migrate into the dehydrated parts, causing those to melt. These melts in turn migrate into the overlying mantle wedge, where they trigger further melting. Our results provide a physical model to explain melting of the subducted plate and mass transfer from the slab to the mantle beneath arcs where relatively young oceanic lithosphere is subducted.

Slab melting beneath the Cascades Arc driven by dehydration of altered oceanic peridotite

USGS Publications Warehouse

Walowski, Kristina J; Wallace, Paul J.; Hauri, E.H.; Wada, I.; Clynne, Michael A.

2015-01-01

Water is returned to Earth’s interior at subduction zones. However, the processes and pathways by which water leaves the subducting plate and causes melting beneath volcanic arcs are complex; the source of the water—subducting sediment, altered oceanic crust, or hydrated mantle in the downgoing plate—is debated; and the role of slab temperature is unclear. Here we analyse the hydrogen-isotope and trace-element signature of melt inclusions in ash samples from the Cascade Arc, where young, hot lithosphere subducts. Comparing these data with published analyses, we find that fluids in the Cascade magmas are sourced from deeper parts of the subducting slab—hydrated mantle peridotite in the slab interior—compared with fluids in magmas from the Marianas Arc, where older, colder lithosphere subducts. We use geodynamic modelling to show that, in the hotter subduction zone, the upper crust of the subducting slab rapidly dehydrates at shallow depths. With continued subduction, fluids released from the deeper plate interior migrate into the dehydrated parts, causing those to melt. These melts in turn migrate into the overlying mantle wedge, where they trigger further melting. Our results provide a physical model to explain melting of the subducted plate and mass transfer from the slab to the mantle beneath arcs where relatively young oceanic lithosphere is subducted.

Preliminary assessment of water chemistry related to groundwater flooding in Wawarsing, New York, 2009-11

USGS Publications Warehouse

Brown, Craig J.; Eckhardt, David A.; Stumm, Frederick; Chu, Anthony

2012-01-01

Water-quality samples collected in an area prone to groundwater flooding in Wawarsing, New York, were analyzed and assessed to better understand the hydrologic system and to aid in the assessment of contributing water sources. Above average rainfall over the past decade, and the presence of a pressurized water tunnel that passes about 700 feet beneath Wawarsing, could both contribute to groundwater flooding. Water samples were collected from surface-water bodies, springs, and wells and analyzed for major and trace inorganic constituents, dissolved gases, age tracers, and stable isotopes. Distinct differences in chemistry exist between tunnel water and groundwater in unconsolidated deposits and in bedrock, and among groundwater samples collected from some bedrock wells during high head pressure and low head pressure of the Rondout-West Branch Tunnel. Samples from bedrock wells generally had relatively higher concentrations of sulfate (SO42-), strontium (Sr), barium (Ba), and lower concentrations of calcium (Ca) and bicarbonate (HCO3-), as compared to unconsolidated wells. Differences in stable-isotope ratios among oxygen-18 to oxygen-16 (δ18O), hydrogen-2 to hydrogen-1 (δ2H), sulfur-34 to sulfur-32(δ34S) of SO42-, Sr-87 to Sr-86 (87Sr/86Sr), and C-13 to C-12 (δ13C) of dissolved inorganic carbon (DIC) indicate a potential for distinguishing water in the Delaware-West Branch Tunnel from native groundwater. For example, 87Sr/86Sr ratios were more depleted in groundwater samples from most bedrock wells, as compared to samples from surface-water sources, springs, and wells screened in unconsolidated deposits in the study area. Age-tracer data provided useful information on pathways of the groundwater-flow system, but were limited by inherent problems with dissolved gases in bedrock wells. The sulfur hexafluoride (SF6) and (or) chlorofluorocarbons (CFCs) apparent recharge years of most water samples from wells screened in unconsolidated deposits and springs ranged from 2003 to 2010 (current) and indicate short flow paths from the point of groundwater recharge. All but three of the samples from bedrock wells had interference problems with dissolved gases, mainly caused by excess air from degassing of hydrogen sulfide and methane. The SF6 and (or) CFC apparent recharge years of samples from three of the bedrock wells ranged from the 1940s to the early 2000s; the sample with the early 2000s recharge year was from a flowing artesian well that was chemically similar to water samples collected at the influent to the tunnel at Rondout Reservoir and the most hydraulically responsive to water tunnel pressure compared to other bedrock wells. Data described in this report can be used, together with hydrogeologic data, to improve the understanding of source waters and groundwater-flow patterns and pathways, and to help assess the mixing of different source waters in water samples. Differences in stable isotope ratios, major and trace constituent concentrations, saturation indexes, tritium concentrations, and apparent groundwater ages will be used to estimate the proportion of water that originates from Rondout-West Branch Tunnel leakage.

Cosmic radiation exposure of biological test systems during the EXPOSE-E mission.

PubMed

Berger, Thomas; Hajek, Michael; Bilski, Pawel; Körner, Christine; Vanhavere, Filip; Reitz, Günther

2012-05-01

In the frame of the EXPOSE-E mission on the Columbus external payload facility EuTEF on board the International Space Station, passive thermoluminescence dosimeters were applied to measure the radiation exposure of biological samples. The detectors were located either as stacks next to biological specimens to determine the depth dose distribution or beneath the sample carriers to determine the dose levels for maximum shielding. The maximum mission dose measured in the upper layer of the depth dose part of the experiment amounted to 238±10 mGy, which relates to an average dose rate of 408±16 μGy/d. In these stacks of about 8 mm height, the dose decreased by 5-12% with depth. The maximum dose measured beneath the sample carriers was 215±16 mGy, which amounts to an average dose rate of 368±27 μGy/d. These values are close to those assessed for the interior of the Columbus module and demonstrate the high shielding of the biological experiments within the EXPOSE-E facility. Besides the shielding by the EXPOSE-E hardware itself, additional shielding was experienced by the external structures adjacent to EXPOSE-E, such as EuTEF and Columbus. This led to a dose gradient over the entire exposure area, from 215±16 mGy for the lowest to 121±6 mGy for maximum shielding. Hence, the doses perceived by the biological samples inside EXPOSE-E varied by 70% (from lowest to highest dose). As a consequence of the high shielding, the biological samples were predominantly exposed to galactic cosmic heavy ions, while electrons and a significant fraction of protons of the radiation belts and solar wind did not reach the samples.

Comparative analysis of bones, mites, soil chemistry, nematodes and soil micro-eukaryotes from a suspected homicide to estimate the post-mortem interval.

PubMed

Szelecz, Ildikó; Lösch, Sandra; Seppey, Christophe V W; Lara, Enrique; Singer, David; Sorge, Franziska; Tschui, Joelle; Perotti, M Alejandra; Mitchell, Edward A D

2018-01-08

Criminal investigations of suspected murder cases require estimating the post-mortem interval (PMI, or time after death) which is challenging for long PMIs. Here we present the case of human remains found in a Swiss forest. We have used a multidisciplinary approach involving the analysis of bones and soil samples collected beneath the remains of the head, upper and lower body and "control" samples taken a few meters away. We analysed soil chemical characteristics, mites and nematodes (by microscopy) and micro-eukaryotes (by Illumina high throughput sequencing). The PMI estimate on hair 14 C-data via bomb peak radiocarbon dating gave a time range of 1 to 3 years before the discovery of the remains. Cluster analyses for soil chemical constituents, nematodes, mites and micro-eukaryotes revealed two clusters 1) head and upper body and 2) lower body and controls. From mite evidence, we conclude that the body was probably brought to the site after death. However, chemical analyses, nematode community analyses and the analyses of micro-eukaryotes indicate that decomposition took place at least partly on site. This study illustrates the usefulness of combining several lines of evidence for the study of homicide cases to better calibrate PMI inference tools.

Fine-scale spatial distribution of orchid mycorrhizal fungi in the soil of host-rich grasslands.

PubMed

Voyron, Samuele; Ercole, Enrico; Ghignone, Stefano; Perotto, Silvia; Girlanda, Mariangela

2017-02-01

Mycorrhizal fungi are essential for the survival of orchid seedlings under natural conditions. The distribution of these fungi in soil can constrain the establishment and resulting spatial arrangement of orchids at the local scale, but the actual extent of occurrence and spatial patterns of orchid mycorrhizal (OrM) fungi in soil remain largely unknown. We addressed the fine-scale spatial distribution of OrM fungi in two orchid-rich Mediterranean grasslands by means of high-throughput sequencing of fungal ITS2 amplicons, obtained from soil samples collected either directly beneath or at a distance from adult Anacamptis morio and Ophrys sphegodes plants. Like ectomycorrhizal and arbuscular mycobionts, OrM fungi (tulasnelloid, ceratobasidioid, sebacinoid and pezizoid fungi) exhibited significant horizontal spatial autocorrelation in soil. However, OrM fungal read numbers did not correlate with distance from adult orchid plants, and several of these fungi were extremely sporadic or undetected even in the soil samples containing the orchid roots. Orchid mycorrhizal 'rhizoctonias' are commonly regarded as unspecialized saprotrophs. The sporadic occurrence of mycobionts of grassland orchids in host-rich stands questions the view of these mycorrhizal fungi as capable of sustained growth in soil. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

Tag retention, growth, and survival of red swamp crayfish Procambarus clarkii marked with coded wire tags

USGS Publications Warehouse

Isely, J.J.; Eversole, A.G.

1998-01-01

Juvenile red swamp crayfish (or crawfish), Procambarus clarkii (20-41 mm in total length) were collected from a crayfish culture pond by dipnetting and tagged with sequentially numbered, standard length, binary-coded wire tags. Four replicates of 50 crayfish were impaled perpendicular to the long axis of the abdomen with a fixed needle. Tags were injected transversely into the ventral surface of the first or second abdominal segment and were imbedded in the musculature just beneath the abdominal sternum. Tags were visible upon inspection. Additionally, two replicates of 50 crayfish were not tagged and were used as controls. Growth, survival, and tag retention were evaluated after 7 d in individual containers, after 100 d in aquaria, and after 200 d in field cages. Tag retention during each sample period was 100%, and average mortality of tagged crayfish within 7 d of tagging was 1%. Mortality during the remainder of the study was high (75-91%) but was similar between treatment and control samples. Most of the deaths were probably due to cannibalism. Average total length increased threefold during the course of the study, and crayfish reached maturity. Because crayfish were mature by the end of the study, we concluded that the coded wire tag was retained through the life history of the crayfish.

Effects of climate on the productivity of desert truffles beneath hyper-arid conditions.

PubMed

Bradai, Lyès; Bissati, Samia; Chenchouni, Haroun; Amrani, Khaled

2015-07-01

Desert truffles are edible hypogenous fungi that are very well adapted to conditions of aridity in arid and semi-arid regions. This study aims to highlight the influence of climatic factors on the productivity of desert truffles under hyper-arid climatic conditions of the Sahara Desert in Algeria, with assumptions that the more varying climatic factors, mainly rainfall, are more crucial for the development and production of desert truffles. At seven separate sites, desert truffles were collected by systematic sampling between 2006 and 2012. The effects of climate parameters of each site on the productivities (g/ha/year) of desert truffle species were tested using generalized linear models (GLMs). The annual mean of the total production recorded for all three harvested species (Terfezia arenaria, Terfezia claveryi, and Tirmania nivea) was 785.43 ± 743.39 g/ha. Tirmania nivea was commonly present over the sampled sites with an occurrence of 70 ± 10.1%. GLMs revealed that total and specific productivities were closely positively related to autumnal precipitations occurring during October-December, which is the critical pre-breeding period for both desert truffles and host plant species. The other climatic parameters have statistically no effect on the annual variation of desert truffle productivity.

Imaging paleoslabs in the D″ layer beneath Central America and the Caribbean using seismic waveform inversion

PubMed Central

Borgeaud, Anselme F. E.; Kawai, Kenji; Konishi, Kensuke; Geller, Robert J.

2017-01-01

D″ (Dee double prime), the lowermost layer of the Earth’s mantle, is the thermal boundary layer (TBL) of mantle convection immediately above the Earth’s liquid outer core. As the origin of upwelling of hot material and the destination of paleoslabs (downwelling cold slab remnants), D″ plays a major role in the Earth’s evolution. D″ beneath Central America and the Caribbean is of particular geodynamical interest, because the paleo- and present Pacific plates have been subducting beneath the western margin of Pangaea since ~250 million years ago, which implies that paleoslabs could have reached the lowermost mantle. We conduct waveform inversion using a data set of ~7700 transverse component records to infer the detailed three-dimensional S-velocity structure in the lowermost 400 km of the mantle in the study region so that we can investigate how cold paleoslabs interact with the hot TBL above the core-mantle boundary (CMB). We can obtain high-resolution images because the lowermost mantle here is densely sampled by seismic waves due to the full deployment of the USArray broadband seismic stations during 2004–2015. We find two distinct strong high-velocity anomalies, which we interpret as paleoslabs, just above the CMB beneath Central America and Venezuela, respectively, surrounded by low-velocity regions. Strong low-velocity anomalies concentrated in the lowermost 100 km of the mantle suggest the existence of chemically distinct denser material connected to low-velocity anomalies in the lower mantle inferred by previous studies, suggesting that plate tectonics on the Earth’s surface might control the modality of convection in the lower mantle. PMID:29209659

High resolution P-wave velocity structure beneath Northeastern Tibet from multiscale seismic tomography

NASA Astrophysics Data System (ADS)

Guo, B.; Gao, X.; Chen, J.; Liu, Q.; Li, S.

2016-12-01

The continuing collision of the northward advancing Indian continent with the Eurasia results in the high elevations and thickened Tibetan Plateau. Numerous geologic and geophysical studies engaged in the mechanics of the Tibetan Plateau deformation and uplift. Many seismic experiments were deployed in south and central Tibet, such as INDEPTH and Hi-climb, but very few in northeastern Tibet. Between 2013 and 2015, The China Seismic Array-experiment operated 670 broadband seismic stations with an average station spacing of 35km. This seismic array located in northeastern Tibet and covered the Qilian Mountains, Qaidam Basin, and part of Songpan-Ganzi, Gobi-Alashan, Yangzi, and Ordos. A new multiscale seismic traveltime tomography technique with sparsity constrains were used to map the upper mantle P-wave velocity structure beneath northeastern Tibet. The seismic tomography algorithm employs sparsity constrains on the wavelet representation velocity model via the L1-norm regularization. This algorithm can efficiently deal with the uneven-sampled volume, and give multiscale images of the model. Our preliminary results can be summarized as follows: 1) in the upper mantle down to 200km, significate low-velocity anomalies exist beneath the northeastern Tibet, and slight high-velocity anomalies beneath the Qaidam basin; 2) under Gobi-Alashan, Yangzi, and Ordos, high-velocity anomalies appear to extend to a depth of 250km, this high-velocity may correspond to the lithosphere; 3) there exist relative high-velocity anomalies at depth of 250km-350km underneath north Tibet, which suggests lithospheric delamination; 4) the strong velocity contrast between north Tibet and Yangzi, Gabi-Alashan is visible down to 200km, which implies the north Tibet boundary.

Further constraints on the African superplume structure

NASA Astrophysics Data System (ADS)

Ni, Sidao; Helmberger, Don V.

2003-11-01

It is well established that there is a large-scale low velocity structure in the lowermost mantle beneath Africa, extending from the Southeastern Atlantic Ocean to the Southwestern Indian Ocean with a volume greater than 10 billion km 3 (>7000 km long, 1000 km across and 1200 km high) [Earth Planet. Sci. Lett. 206 (2003) 119]. This low velocity structure is often called the African superplume. Various studies also require sharp boundaries for the plume. However, as for its height and shear velocity reduction, there has been some controversy, especially concerning the velocities at the core-mantle-boundary (CMB). Here, we present an assortment of phases involving S diff, SKS, S and S cS with both vertical and horizontal paths sampling a 2D corridor through the structure. Travel time and waveform modeling of these seismic phases argues for a model with shear velocity reduction of approximately 3% within the superplume (which is basically a 200 km thick layer low velocity layer beneath the Southern Atlantic Ocean, and a 1200 km high structure beneath South Africa), and against a model of a substantially reduced low velocity layer (up to 10%, 300 km) beneath the superplume. We also analyzed P diff and the differential times of P cP-P and compared them with S diff and S cS-S observations along the same great circle paths. The P-velocity is not very anomalous, at most -0.5%, much smaller than -1% as expected from a thermal anomaly with -3% lower S-velocity [Geophys. Res. Lett. 27 (2000) 421], thus again arguing for a chemical origin which was suggested from the modeling of African superplume sharp sides [Science 296 (2002) 1850].

Integrating a High Resolution Optically Pumped Magnetometer with a Multi-Rotor UAV towards 3-D Magnetic Gradiometry

NASA Astrophysics Data System (ADS)

Braun, A.; Walter, C. A.; Parvar, K.

2016-12-01

The current platforms for collecting magnetic data include dense coverage, but low resolution traditional airborne surveys, and high resolution, but low coverage terrestrial surveys. Both platforms leave a critical observation gap between the ground surface and approximately 100m above ground elevation, which can be navigated efficiently by new technologies, such as Unmanned Aerial Vehicles (UAVs). Specifically, multi rotor UAV platforms provide the ability to sense the magnetic field in a full 3-D tensor, which increases the quality of data collected over other current platform types. Payload requirements and target requirements must be balanced to fully exploit the 3-D magnetic tensor. This study outlines the integration of a GEM Systems Cesium Vapour UAV Magnetometer, a Lightware SF-11 Laser Altimeter and a uBlox EVK-7P GPS module with a DJI s900 Multi Rotor UAV. The Cesium Magnetometer is suspended beneath the UAV platform by a cable of varying length. A set of surveys was carried out to optimize the sensor orientation, sensor cable length beneath the UAV and data collection methods of the GEM Systems Cesium Vapour UAV Magnetometer when mounted on the DJI s900. The target for these surveys is a 12 inch steam pipeline located approximately 2 feet below the ground surface. A systematic variation of cable length, sensor orientation and inclination was conducted. The data collected from the UAV magnetometer was compared to a terrestrial survey conducted with the GEM GST-19 Proton Procession Magnetometer at the same elevation, which also served a reference station. This allowed for a cross examination between the UAV system and a proven industry standard for magnetic field data collection. The surveys resulted in optimizing the above parameters based on minimizing instrument error and ensuring reliable data acquisition. The results demonstrate that optimizing the UAV magnetometer survey can yield to industry standard measurements.

Geophysical Investigations of Magma Plumbing Systems at Cerro Negro Volcano, Nicaragua

NASA Astrophysics Data System (ADS)

MacQueen, Patricia Grace

Cerro Negro near Leon, Nicaragua is a very young (163 years), relatively small basaltic cinder cone volcano that has been unusually active during its short lifespan (recurrence interval 6--7 years), presenting a significant hazard to nearby communities. Previous studies have raised several questions as to the proper classification of Cerro Negro and its relation to neighboring Las Pilas-El Hoyo volcano. Analysis of Bouguer gravity data collected at Cerro Negro has revealed connected positive density anomalies beneath Cerro Negro and Las Pilas-El Hoyo. These findings suggest that eruptions at Cerro Negro may be tapping a large magma reservoir beneath Las Pilas-El Hoyo, implying that Cerro Negro should be considered the newest vent on the Las Pilas-El Hoyo volcanic complex. As such, it is possible that the intensity of volcanic hazards at Cerro Negro may eventually increase in the future to resemble those pertaining to a stratovolcano. Keywords: Cerro Negro; Las Pilas-El Hoyo; Bouguer gravity; magmatic plumbing systems; potential fields; volcano.

A case study of cumulus formation beneath a stratocumulus sheet: Its structure and effect on boundary layer budgets

NASA Technical Reports Server (NTRS)

Barlow, Roy W.; Nicholls, S.

1990-01-01

On several occasions during the FIRE Marine Stratocumulus IFO off the California coast, small cumulus were observed to form during the morning beneath the main stratocumulus (Sc) deck. This occurs in the type of situation described by Turton and Nicholls (1987) in which there is insufficient generation of turbulent kinetic energy (TKE) from the cloudtop or the surface to sustain mixing throughout the layer, and a separation of the surface and cloud layers occurs. The build up of humidity in the surface layer allows cumuli to form, and the more energetic of these may penetrate back into the Sc deck, reconnecting the layers. The results presented were collected by the UKMO C-130 aircraft flying in a region where these small cumulus had grown to the extent that they had penetrated into the main Sc deck above. The structure of these penetrative cumulus are examined and their implications on the layer flux and radiation budget discussed.

Evaluation of Airborne l- Band Multi-Baseline Pol-Insar for dem Extraction Beneath Forest Canopy

NASA Astrophysics Data System (ADS)

Li, W. M.; Chen, E. X.; Li, Z. Y.; Jiang, C.; Jia, Y.

2018-04-01

DEM beneath forest canopy is difficult to extract with optical stereo pairs, InSAR and Pol-InSAR techniques. Tomographic SAR (TomoSAR) based on different penetration and view angles could reflect vertical structure and ground structure. This paper aims at evaluating the possibility of TomoSAR for underlying DEM extraction. Airborne L-band repeat-pass Pol-InSAR collected in BioSAR 2008 campaign was applied to reconstruct the 3D structure of forest. And sum of kronecker product and algebraic synthesis algorithm were used to extract ground structure, and phase linking algorithm was applied to estimate ground phase. Then Goldstein cut-branch approach was used to unwrap the phases and then estimated underlying DEM. The average difference between the extracted underlying DEM and Lidar DEM is about 3.39 m in our test site. And the result indicates that it is possible for underlying DEM estimation with airborne L-band repeat-pass TomoSAR technique.

Anatomy of a metamorphic core complex: seismic refraction/wide-angle reflection profiling in southeastern California and western Arizona

USGS Publications Warehouse

McCarthy, J.; Larkin, S.P.; Fuis, G.S.; Simpson, R.W.; Howard, K.A.

1991-01-01

The metamorphic core complex belt in southeastern California and western Arizona is a NW-SE trending zone of unusually large Tertiary extension and uplift. Midcrustal rocks exposed in this belt raise questions about the crustal thickness, crustal structure, and the tectonic evolution of the region. Three seismic refraction/wide-angle reflection profiles were collected to address these issues. The results presented here, which focus on the Whipple and Buckskin-Rawhide mountains, yield a consistent three-dimensiional image of this part of the metamorphic core complex belt. The final model consists of a thin veneer (<2 km) of upper plate and fractured lower plate rocks (1.5-5.5 km s-1) overlying a fairly homogeneous basement (~6.0 km s-1) and a localized high-velocity (6.4 km s -1) body situated beneath the western Whipple Mountains. A prominent midcrustal reflection is identified beneath the Whipple and Buckskin Rawhide mountains between 10 and 20km depth. -from Authors

Hydrogeology and water quality of the stratified-drift aquifer in the Pony Hollow Creek Valley, Tompkins County, New York

USGS Publications Warehouse

Bugliosi, Edward F.; Miller, Todd S.; Reynolds, Richard J.

2014-01-01

The lithology, areal extent, and the water-table configuration in stratified-drift aquifers in the northern part of the Pony Hollow Creek valley in the Town of Newfield, New York, were mapped as part of an ongoing aquifer mapping program in Tompkins County. Surficial geologic and soil maps, well and test-boring records, light detection and ranging (lidar) data, water-level measurements, and passive-seismic surveys were used to map the aquifer geometry, construct geologic sections, and determine the depth to bedrock at selected locations throughout the valley. Additionally, water-quality samples were collected from selected streams and wells to characterize the quality of surface and groundwater in the study area. Sedimentary bedrock underlies the study area and is overlain by unstratified drift (till), stratified drift (glaciolacustrine and glaciofluvial deposits), and recent post glacial alluvium. The major type of unconsolidated, water-yielding material in the study area is stratified drift, which consists of glaciofluvial sand and gravel, and is present in sufficient amounts in most places to form an extensive unconfined aquifer throughout the study area, which is the source of water for most residents, farms, and businesses in the valleys. A map of the water table in the unconfined aquifer was constructed by using (1) measurements made between the mid-1960s through 2010, (2) control on the altitudes of perennial streams at 10-foot contour intervals from lidar data collected by Tompkins County, and (3) water surfaces of ponds and wetlands that are hydraulically connected to the unconfined aquifer. Water-table contours indicate that the direction of groundwater flow within the stratified-drift aquifer is predominantly from the valley walls toward the streams and ponds in the central part of the valley where groundwater then flows southwestward (down valley) toward the confluence with the Cayuta Creek valley. Locally, the direction of groundwater flow is radially away from groundwater mounds that have formed beneath upland tributaries that lose water where they flow on alluvial fans on the margins of the valley. In some places, groundwater that would normally flow toward streams is intercepted by pumping wells. Surface-water samples were collected in 2001 at four sites including Carter, Pony Hollow (two sites), and Chafee Creeks, and from six wells throughout the aquifer. Calcium dominates the cation composition and bicarbonate dominates the anion composition in groundwater and surface-water samples and none of the common inorganic constituents collected exceeded any Federal or State water-quality standards. Groundwater samples were collected from six wells all completed in the unconfined sand and gravel aquifer. Concentrations of calcium and magnesium dominated the ionic composition of the groundwater in all wells sampled. Nitrate, orthophosphate, and trace metals were detected in all groundwater samples, but none were more than U.S. Environmental Protection Agency or New York State Department of Health regulatory limits.

Estimated hydrostatic/cryostatic pressures during emplacement of pillow lavas at Undirhlithar quarry, Reykjanes Peninsula, southwest Iceland

NASA Astrophysics Data System (ADS)

Hiatt, A. R.; Pollock, M.; Edwards, B. R.; Hauksdottir, S.; Williams, M.; Reinthal, M.

2013-12-01

Undirhlithar quarry exposes the interior of the northern end of a pillow-dominated tindar on the Reykjanes Peninsula in southwest Iceland. The Reykjanes Peninsula has several tindars and tuyas, which are glaciovolcanic features emplaced within or beneath ice. Such features are rapidly becoming one of the fundamental tools for estimating paleo-ice thickness in order to better constrain models for reconstructing ice sheet extents. In Iceland, most estimates of past ice thickness come from geological evidence, such as the elevation of tuya passage zones (e.g., Pedersen et al., IAVCEI 2013), although various theoretical attempts have been made as well. For example, estimations have been calculated from postglacial isostatic uplift (e.g., Le Breton et al., J Geol Soc Lond 2010). An alternative approach for estimating paleo-ice thickness is to use the volatile contents of glaciovolcanic glasses. The extent of degassing of a volatile-saturated magma is, in part, a function of the pressure at which the magma is quenched to form glass. Therefore, pressures calculated from measured H2O contents in quenched basaltic pillow lava rims should record emplacement conditions. On the Reykjanes Peninsula, two studies have used this method to calculate past ice thickness: Mercurio et al. (AGU 2009) estimated a maximum thickness of 400 m for Sveifuháls, several km south of Undirhlithar. Schopka et al. (JGR 2006) analyzed glasses from the predominantly fragmental Helgafell ridge, ~ 2.5 km to the NE of Undirhlithar, and estimated a quenching pressure equivalent of up to ~ 200 m of ice; however, they noted that this disagrees with their estimate of overall ice thickness of ~ 500 m, based on the elevation of Helgafell. Although a growing number of studies are using volatile contents in a range of glass compositions to reconstruct ice thicknesses, many questions remain about the validity of the approach. This study focuses on the reproducibility of the technique using samples from Undirhlithar. Sixteen glass samples were collected from the quenched rinds of twelve different pillows. Four of these samples were collected from a single pillow rim and the others were collected from pillows very close in elevation around the quarry. Two samples were collected several tens of meters above the rest. Each sample was examined under a stereoscope and the freshest chips were selected for analysis. Major and trace element compositions will be analyzed via DCP-AES and ICP-MS, respectively, and volatile contents will be analyzed by FTIR. A preliminary calculation using the average Undirhlithar pillow lava composition, the H2O content of a sample collected in the quarry by Nichols et al. (Earth Planet Sci Lett 2002; 0.4 wt%), and CO2 concentrations from 0 - 20 ppm yields quench pressures of ~ 42 - 56 bar, equivalent to water depths of ~ 450 - 575 m and consistent with previous estimates for ice thickness on the Reykjanes Peninsula.

Nutrients in groundwaters of the conterminous United States, 1992-1995

USGS Publications Warehouse

Nolan, B.T.; Stoner, J.D.

2000-01-01

Results of a national water quality assessment indicate that nitrate is detected in 71% of groundwater samples, more than 13 times as often as ammonia, nitrite, organic nitrogen, and orthophosphate, based on a common detection threshold of 0.2 mg/L. Shallow groundwater (typically 5 m deep or less) beneath agricultural land has the highest median nitrate concentration (3.4 mg/L), followed by shallow groundwater beneath urban land (1.6 mg/L) and deeper groundwater in major aquifers (0.48 mg/L). Nitrate exceeds the maximum contaminant level, 10 mg/L as nitrogen, in more than 15% of groundwater samples from 4 of 33 major aquifers commonly used as a source of drinking water. Nitrate concentration in groundwater is variable and depends on interactions among several factors, including nitrogen loading, soil type, aquifer permeability, recharge rate, and climate. For a given nitrogen loading, factors that generally increase nitrate concentration in groundwater include well-drained soils, fractured bedrock, and irrigation. Factors that mitigate nitrate contamination of groundwater include poorly drained soils, greater depth to groundwater, artificial drainage systems, intervening layers of unfractured bedrock, a low rate of groundwater recharge, and anaerobic conditions in aquifers.

A preliminary report on histological outcome of pulpotomy with endodontic biomaterials vs calcium hydroxide.

PubMed

Nosrat, Ali; Peimani, Ali; Asgary, Saeed

2013-11-01

The purpose of the study was to evaluate human dental pulp response to pulpotomy with calcium hydroxide (CH), mineral trioxide aggregate (MTA), and calcium enriched mixture (CEM) cement. A total of nine erupted third molars were randomly assigned to each pulpotomy group. The same clinician performed full pulpotomies and coronal restorations. The patients were followed clinically for six months; the teeth were then extracted and prepared for histological assessments. The samples were blindly assessed by an independent observer for pulp vitality, pulp inflammation, and calcified bridge formation. All patients were free of clinical signs/symptoms of pulpal/periradicular diseases during the follow up period. In CH group, one tooth had necrotic radicular pulp; other two teeth in this group had vital uninflamed pulps with complete dentinal bridge formation. In CEM cement and MTA groups all teeth had vital uninflamed radicular pulps. A complete dentinal bridge was formed beneath CEM cement and MTA in all roots. Odontoblast-like cells were present beneath CEM cement and MTA in all samples. This study revealed that CEM cement and MTA were reliable endodontic biomaterials in full pulpotomy treatment. In contrast, the human dental pulp response to CH might be unpredictable.

Soil property control of biogeochemical processes beneath two subtropical stormwater infiltration basins

USGS Publications Warehouse

O'Reilly, Andrew M.; Wanielista, Martin P.; Chang, Ni-Bin; Harris, Willie G.; Xuan, Zhemin

2012-01-01

Substantially different biogeochemical processes affecting nitrogen fate and transport were observed beneath two stormwater infiltration basins in north-central Florida. Differences are related to soil textural properties that deeply link hydroclimatic conditions with soil moisture variations in a humid, subtropical climate. During 2008, shallow groundwater beneath the basin with predominantly clayey soils (median, 41% silt+clay) exhibited decreases in dissolved oxygen from 3.8 to 0.1 mg L-1 and decreases in nitrate nitrogen (NO3-–N) from 2.7 mg L-1 to -1, followed by manganese and iron reduction, sulfate reduction, and methanogenesis. In contrast, beneath the basin with predominantly sandy soils (median, 2% silt+clay), aerobic conditions persisted from 2007 through 2009 (dissolved oxygen, 5.0–7.8 mg L-1), resulting in NO3-–N of 1.3 to 3.3 mg L-1 in shallow groundwater. Enrichment of d15N and d18O of NO3- combined with water chemistry data indicates denitrification beneath the clayey basin and relatively conservative NO3- transport beneath the sandy basin. Soil-extractable NO3-–N was significantly lower and the copper-containing nitrite reductase gene density was significantly higher beneath the clayey basin. Differences in moisture retention capacity between fine- and coarse-textured soils resulted in median volumetric gas-phase contents of 0.04 beneath the clayey basin and 0.19 beneath the sandy basin, inhibiting surface/subsurface oxygen exchange beneath the clayey basin. Results can inform development of soil amendments to maintain elevated moisture content in shallow soils of stormwater infiltration basins, which can be incorporated in improved best management practices to mitigate NO3- impacts.

Soil property control of biogeochemical processes beneath two subtropical stormwater infiltration basins.

PubMed

O'Reilly, Andrew M; Wanielista, Martin P; Chang, Ni-Bin; Harris, Willie G; Xuan, Zhemin

2012-01-01

Substantially different biogeochemical processes affecting nitrogen fate and transport were observed beneath two stormwater infiltration basins in north-central Florida. Differences are related to soil textural properties that deeply link hydroclimatic conditions with soil moisture variations in a humid, subtropical climate. During 2008, shallow groundwater beneath the basin with predominantly clayey soils (median, 41% silt+clay) exhibited decreases in dissolved oxygen from 3.8 to 0.1 mg L and decreases in nitrate nitrogen (NO-N) from 2.7 mg L to <0.016 mg L, followed by manganese and iron reduction, sulfate reduction, and methanogenesis. In contrast, beneath the basin with predominantly sandy soils (median, 2% silt+clay), aerobic conditions persisted from 2007 through 2009 (dissolved oxygen, 5.0-7.8 mg L), resulting in NO-N of 1.3 to 3.3 mg L in shallow groundwater. Enrichment of δN and δO of NO combined with water chemistry data indicates denitrification beneath the clayey basin and relatively conservative NO transport beneath the sandy basin. Soil-extractable NO-N was significantly lower and the copper-containing nitrite reductase gene density was significantly higher beneath the clayey basin. Differences in moisture retention capacity between fine- and coarse-textured soils resulted in median volumetric gas-phase contents of 0.04 beneath the clayey basin and 0.19 beneath the sandy basin, inhibiting surface/subsurface oxygen exchange beneath the clayey basin. Results can inform development of soil amendments to maintain elevated moisture content in shallow soils of stormwater infiltration basins, which can be incorporated in improved best management practices to mitigate NO impacts. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Comments on “Arc magmatism and subduction history beneath the Zagros Mountains, Iran: A new report of adakites and geodynamic consequences” by J. Omrani, P. Agard, H. Whitechurch, M. Bennoit, G. Prouteau, L. Jolivet

NASA Astrophysics Data System (ADS)

Aftabi, Alijan; Atapour, Habibeh

2009-12-01

Based on the imprecise geochemical data for 62 samples from Qom, Anar and Baft regions in central Iranian magmatic arc Omrani et al. (Omrani, J., Agard, P., Witechurch, H., Benoit, M., Prouteau, G., Jolivet, L., 2008. Arc magmatism and subduction history beneath the Zagsros Mountains, Iran: A new report of adakites and geodynamic consequences. Lithos 106, 380-398.), suggested that all studied magmatic rocks display the geochemical affinity of subduction-related calc-alkalic rock suites. Here, we demonstrate that the incorrect altered and variable geochemical data (e.g., Al 2O 3, Sr, Y, Ni, Cr, SiO 2, Na 2O, La/Yb and Th/Ce), show that most of the samples actually display calc-alkaline, shoshonitic and calc-alkalic-adakitic affinities. Furthermore, as a result of alteration, rock samples of similar age (e.g., Qom) indicate both adakitic and non-adakitic compositional signatures, which is misleading. On the basis of more than 400 previously published geochemical analyses, we suggest that, after eliminating the false geochemical signatures, the calc-alkaline and adakitic affinities of the central Iranian magmatic arc are due to flat subduction and might be related to a second phase of Miocene- Pliocene porphyry copper mineralization, which is a considerable exploration target and thus merits further investigation.

Effect of Georgetown Lake on the water quality of Clear Creek, Georgetown, Colorado, 1997-98

USGS Publications Warehouse

Cuffin, Sally M.; Chafin, Daniel T.

2000-01-01

Georgetown Lake is a recreational reservoir located in the upper Clear Creek Basin, a designated Superfund site because of extensive metal mining in the past. Metals concentrations in Clear Creek increase as the stream receives runoff from mining-affected areas. In 1997, the U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency, began a study to determine the effect of the reservoir on the transport of metals in Clear Creek. A bathymetric survey determined the capacity of the reservoir to be about 440 acre-feet of water, which remained constant during the study. Average water residence time in the reservoir is about 1?3 days during high flow. During low flow (10 cubic feet per second), average residence is about 22 days without ice cover and about 15 days with a 3-foot-thick ice cover. Sediment samples collected from the bottom of Georgetown Lake contained substantial concentrations of iron (average 25,500 milligrams per kilogram), aluminum (average 12,300 milligrams per kilogram), zinc (2,830 milligrams per kilogram), lead (618 milligrams per kilogram), manganese (548 milligrams per kilogram), and sulfide minerals (average 602 milligrams per kilogram as S). Sediment also contained abundant sulfate-reducing bacteria, indicating anoxic conditions. Algae and diatoms common to cold-water lakes were identified in sediment samples; one genus of algae is known to adapt to low-light conditions such as exist beneath ice cover. Vertical profiles of temperature, specific conductance, pH, and dissolved-oxygen concentrations were measured in the reservoir on July 28, 1997, when inflow to the reservoir was about 170 cubic feet per second and average residence time of water was about 1.3 days, and on February 13, 1998, when the reservoir was covered with about 3 feet of ice, inflow was about 15 cubic feet per second, and average residence time was about 12 days. The measurements on July 28, 1997, showed that the reservoir water was well mixed, although pH and dissolved oxygen concentrations were increased by photosynthesis near the bottom of the reservoir. Measurements on February 13, 1998, indicated thermal and chemical stratification with warmer water (about 4 degrees Celsius) beneath colder water and increases in pH and dissolved oxygen concentrations generally occurring near the top of the warmer layer. Concentrations of dissolved oxygen were saturated to oversaturated throughout the water column on both dates, although the concentrations were greater on February 13, 1998, because of colder temperature and photosynthesis. Median pH was about 0.5 unit higher on February 13, 1998, than on July 28, 1997, largely because the longer residence time on February 13, 1998, allowed greater cumulative effects of photosynthesis. Samples of inflow and outflow water were collected from August 1997 to August 1998. Dissolved cadmium and dissolved lead in inflow and outflow samples exceeded acute and chronic water-quality standards during some of the sampling period, whereas dissolved zinc exceeded both standards in inflow and outflow samples during the entire sampling period. Chromium, nickel, and silver were detected in a few samples at small concentrations. Arsenic, selenium, and thallium were not reported in any water samples. Georgetown Lake removes some metals from inflow water and releases others to outflow water. From August 1997 to August 1998, Georgetown Lake estimated outflow loads were about 21 percent less than the inflow load of cadmium and about 11 percent less than the inflow load of zinc. Estimated inflow loads were about 18 percent less than the outflow load of copper, about 13 percent less than the outflow load of iron, and about 27 percent less than the outflow load of manganese. Inflow and outflow loads of lead were essentially balanced. The outflow load of nitrite plus nitrate was about 14 percent less than the inflow load, probably because of plant uptake.

Constraints on the structure of the crust and lithosphere beneath the Azores Islands from teleseismic receiver functions

NASA Astrophysics Data System (ADS)

Spieker, Kathrin; Rondenay, Stéphane; Ramalho, Ricardo; Thomas, Christine; Helffrich, George

2018-05-01

The Azores Archipelago is located near the Mid-Atlantic Ridge (MAR) and consists of nine islands, resting on both sides of the ridge. Various methods including seismic reflection, gravity and passive seismic imaging have previously been used to investigate the crustal thickness beneath the islands. They have yielded thickness estimates that range between roughly 10 and 30 km, but until now models of the more fine-scale crustal structure have been lacking. Pending questions include the thickness of the volcanic edifice beneath the islands and whether crustal intrusions or even underplating can be observed beneath any island. In this study, we use data from nine seismic stations located on the Azores Islands to investigate the crustal structure with teleseismic P-wave receiver functions. Our results indicate that the base of the volcanic edifice is located approximately 1 to 4 km depth beneath the different islands and that the crust-mantle boundary has an average depth of ˜17 km. There is strong evidence for magmatic underplating beneath the island of São Jorge, and indications that the underplating is also present beneath São Miguel and possibly Santa Maria. Additionally, the seismological lithosphere-asthenosphere boundary, defined as a seismic velocity drop in the uppermost mantle, seems to deepen with increasing distance from the MAR. It has a depth of ˜45 km beneath the islands close to the MAR, compared to depths >70 km beneath the more distal islands.

Interstitial water studies on small core samples, Deep Sea Drilling Project: Leg 10

USGS Publications Warehouse

Manheim, Frank T.; Sayles, Fred L.; Waterman, Lee S.

1973-01-01

Leg 10 interstitial water analyses provide new indications of the distribution of rock salt beneath the floor of the Gulf of Mexico, both confirming areas previously indicated to be underlain by salt bodies and extending evidence of salt distribution to seismically featureless areas in the Sigsbee Knolls trend and Isthmian Embayment. The criterion for presence of salt at depth is a consistent increase in interstitial salinity and chlorinity with depth. Site 86, on the northern margin of the Yucatan Platform, provided no evidence of salt at depth. Thus, our data tend to rule out the suggestion of Antoine and Bryant (1969) that the Sigsbee Knolls salt was squeezed out from beneath the Yucatan Scarp. Cores from Sites 90 and 91, in the central Sigsbee Deep, were not obtained from a great enough depth to yield definite evidence for the presence of buried salt.

Petrological constraints on evolution of continental lithospheric mantle beneath the northwestern Ethiopian plateau: Insight from mantle xenoliths from the Gundeweyn area, East Gojam, Ethiopia

NASA Astrophysics Data System (ADS)

Alemayehu, Melesse; Zhang, Hong-Fu; Zhu, Bin; Fentie, Birhanu; Abraham, Samuel; Haji, Muhammed

2016-01-01

Detailed petrographical observations and in-situ major- and trace-element data for minerals from ten spinel peridotite xenoliths from a new locality in Gundeweyn area, East Gojam, have been examined in order to understand the composition, equilibrium temperature and pressure conditions as well as depletion and enrichment processes of continental lithospheric mantle beneath the Ethiopian plateau. The peridotite samples are very fresh and, with the exception of one spinel harzburgite, are all spinel lherzolites. Texturally, the xenoliths can be divided into two groups as primary and secondary textures. Primary textures are protogranular and porphyroclastic while secondary ones include reaction, spongy and lamellae textures. The Fo content of olivine and Cr# of spinel ranges from 86.5 to 90.5 and 7.7 to 14.1 in the lherzolites, respectively and are 89.8 and 49.8, respectively, in the harzburgite. All of the lherzolites fall into the lower Cr# and Fo region in the olivine-spinel mantle array than the harzburgite, which indicates that they are fertile peridotites that experienced low degrees of partial melting and melt extraction. Orthopyroxene and clinopyroxene show variable Cr2O3 and Al2O3 contents regardless of their lithology. The Mg# of orthopyroxene and clinopyroxene are 87.3 to 90.1 and 85.8 to 90.5 for lherzolite and 90.4 and 91.2 for harzburgite, respectively. The peridotites have been equilibrated at a temperature and pressure ranging from 850 to 1100 °C and 10.2 to 30 kbar, respectively, with the highest pressure record from the harzburgite. They record high mantle heat flow between 60 and 150 mW/m2, which is not typical for continental environments (40 mW/m2). Such a high geotherm in continental area shows the presence of active mantle upwelling beneath the Ethiopian plateau, which is consistent with the tectonic setting of nearby area of the Afar plume. Clinopyroxene of five lherzolites and one harzburgite samples have a LREE enriched pattern and the rest exhibit LREE depletion relative to HREE. These suggest that the lithospheric mantle of the Ethiopian plateau has experienced at least two major processes, specifically, partial melting and metasomatism that produce LREE-depleted and -enriched signature of continental lithospheric mantle, respectively. There is also no clear relationship between degree of LREE enrichment and petrography of the studied peridotite. Based on our data, we conclude that the lithospheric mantle beneath Gundeweyn has experienced melt extraction during and/or before pan-African orogeny and then interacted with various degrees of asthenospheric melt. The interaction is probably related to mantle upwelling, which is mainly focused beneath East Africa rift system (EARS).

The Arctic Gakkel Vents (AGAVE) Expedition: Technology Development and the Search for Deep-Sea Hydrothermal Vent Fields Under the Arctic Ice Cap

NASA Astrophysics Data System (ADS)

Reves-Sohn, R. A.; Singh, H.; Humphris, S.; Shank, T.; Jakuba, M.; Kunz, C.; Murphy, C.; Willis, C.

2007-12-01

Deep-sea hydrothermal fields on the Gakkel Ridge beneath the Arctic ice cap provide perhaps the best terrestrial analogue for volcanically-hosted chemosynthetic biological communities that may exist beneath the ice-covered ocean of Europa. In both cases the key enabling technologies are robotic (untethered) vehicles that can swim freely under the ice and the supporting hardware and software. The development of robotic technology for deep- sea research beneath ice-covered oceans thus has relevance to both polar oceanography and future astrobiological missions to Europa. These considerations motivated a technology development effort under the auspices of NASA's ASTEP program and NSF's Office of Polar Programs that culminated in the AGAVE expedition aboard the icebreaker Oden from July 1 - August 10, 2007. The scientific objective was to study hydrothermal processes on the Gakkel Ridge, which is a key target for global studies of deep-sea vent fields. We developed two new autonomous underwater vehicles (AUVs) for the project, and deployed them to search for vent fields beneath the ice. We conducted eight AUV missions (four to completion) during the 40-day long expedition, which also included ship-based bathymetric surveys, CTD/rosette water column surveys, and wireline photographic and sampling surveys of remote sections of the Gakkel Ridge. The AUV missions, which lasted 16 hours on average and achieved operational depths of 4200 meters, returned sensor data that showed clear evidence of hydrothermal venting, but for a combination of technical reasons and time constraints, the AUVs did not ultimately return images of deep-sea vent fields. Nevertheless we used our wireline system to obtain images and samples of extensive microbial mats that covered fresh volcanic surfaces on a newly discovered set of volcanoes. The microbes appear to be living in regions where reducing and slightly warm fluids are seeping through cracks in the fresh volcanic terrain. These discoveries shed new light on the nature of volcanic and hydrothermal processes in the Arctic basin, and also demonstrate the importance of new technologies for advancing science beneath ice-covered oceans. Operationally, the AUV missions pushed the envelope of deep-sea technology. The recoveries were particularly difficult as it was necessary to have the vehicle find small pools of open water next to the ship, but in some cases the ice was in a state of regional compression such that no open water could be found or created. In these cases a well-calibrated, ship-based, short-baseline acoustic system was essential for successful vehicle recoveries. In all we were able to achieve a variety of operational and technological advances that provide stepping stones for future under-ice robotic missions, both on Earth and perhaps eventually on Europa.

Paradise Lost: Uncertainties in melting and melt extraction processes beneath oceanic spreading ridges

NASA Astrophysics Data System (ADS)

Kelemen, P. B.

2014-12-01

In many ways, decompression melting and focused melt transport beneath oceanic spreading ridges is the best understood igneous process on Earth. However, there are remaining - increasing - uncertainties in interpreting residual mantle peridotites. Indicators of degree of melting in residual peridotite are questionable. Yb concentration and spinel Cr# are affected by (a) small scale variations in reactive melt transport, (b) variable extents of melt extraction, and (c) "impregnation", i.e. partial crystallization of cooling melt in pore space. Roughly 75% of abyssal peridotites have undergone major element refertilization. Many may have undergone several melting events. The following three statements are inconsistent: (1) Peridotite melt productivity beyond cpx exhaustion is > 0.1%/GPa. (2) Crustal thickness is independent of spreading rate at rates > 2 cm/yr full rate (excluding ultra-slow spreading ridges). (3) Thermal models predict, and observations confirm, thick thermal boundary layers beneath slow spreading ridges. If (a) melt productivity is << 0.1%/GPa beyond cpx-out, and (b) cpx-out occurs > 15 km below the seafloor beneath most ridges, then the independence of crustal thickness with spreading rate can be understood. Most sampled peridotites from ridges melted beyond cpx-out. Cpx in these rocks formed via impregnation and/or exsolution during cooling. Most peridotites beneath ridges may undergo cpx exhaustion during decompression melting. This would entail an upward modification of potential temperature estimates. Alternatively, perhaps oceanic crustal thickness does vary with spreading rate but this is masked by complicated tectonics and serpentinization at slow-spreading ridges. Dissolution channels (dunites) are predicted to coalesce downstream, but numerical models of these have not shown why > 95% of oceanic crust forms in a zone < 5 km wide. There may be permeability barriers guiding deeper melt toward the ridge, but field studies have not identified them. Permeable "shear bands" may guide melt to the ridge, but their nature in open systems at natural grain size and strain rates is uncertain. 2D and 3D focused solid upwelling due to melt buoyancy deep in the melting region, where pyroxenes are abundant and permeability is low, may warrant renewed attention.

The inducement of planetary boundary layer mass convergence associated with varying vorticity beneath tropospheric wind maximum

NASA Technical Reports Server (NTRS)

Johnson, D. R.

1984-01-01

The effects of the vorticity distribution are applied to study planetary boundary layer mass convergence beneath free tropospheric wind maximum. For given forcing by viscous and pressure gradient forces beneath a wind maximum, boundary layer cross stream mass transport is increased by anticyclonic vorticity on the right flank and decreased by cyclonic vorticity on the left flank. Such frictionally forced mass transport induces boundary layer mass convergence beneath the relative wind maximum. This result is related to the empirical rule that the most intense convection and severe weather frequently develop beneath the 500 mb zero relative vorticity isopleth.

Geochemical Evolution of Groundwater in the Medicine Lodge Creek Drainage Basin with Implications for the Eastern Snake River Plain Aquifer, Eastern Idaho

NASA Astrophysics Data System (ADS)

Ginsbach, M. L.; Rattray, G. W.; McCurry, M. O.; Welhan, J. A.

2012-12-01

The eastern Snake River Plain aquifer (ESRPA) is an unconfined, continuous aquifer located in a northeast-trending structural basin filled with basaltic lava flows and sedimentary interbeds in eastern Idaho. The ESPRA is not an inert transport system, as it acts as both a sink and source for solutes found in the water. More than 90% of the water recharged naturally to the ESRPA is from the surrounding mountain drainage basins. Consequently, in order to understand the natural geochemistry of water within the ESRPA, the chemistry of the groundwater from the mountain drainage basins must be characterized and the processes that control the chemistry need to be understood. The U.S. Geological Survey, in cooperation with the U.S. Department of Energy and Idaho State University, has been studying these mountain drainage basins to help understand the movement of waste solutes in the ESRPA at the Idaho National Laboratory (INL) in eastern Idaho. This study focuses on the Medicine Lodge Creek drainage basin, which originates in the Beaverhead Mountains, extends onto the eastern Snake River Plain, and contributes recharge to the ESRPA beneath the INL as underflow along the northeastern INL boundary. Water and rock samples taken from the Medicine Lodge Creek drainage basin were analyzed to better understand water/rock interactions occurring in this system and to define the groundwater geochemistry of this drainage basin. Water samples were collected at 10 locations in the drainage basin during June 2012: 6 groundwater wells used for agricultural irrigation or domestic use and 4 springs. These water samples were analyzed for major ions, nutrients, trace metals, isotopes, and dissolved gasses. Samples of rock representative of the basalt, rhyolite, and sediments that occur within the drainage basin also were collected. These samples were analyzed using x-ray diffraction and petrographic study to determine the mineralogical constituents of the rock and the presence and composition of alteration products. The lithologic variability in this area leads to differing water-rock interactions occurring in different parts of the drainage basin. Anthropogenic influences also affect the water; at the far downgradient end of the drainage basin, increased levels of chloride and sulfate in the groundwater suggest an increased influence of irrigation recharge. Results from both water and rock analyses are combined in geochemical modeling software to determine plausible reactions that occur in groundwater collected at the sampling sites.

Developing Planetary Protection Technology: Microbial Diversity and Radiation Resistance of Microorganisms in a Spacecraft Assembly Facility.

NASA Astrophysics Data System (ADS)

Chen, F.; La Duc, M. T.; Baker, A.; Koukol, R.; Barengoltz, J.; Kern, R.; Venkateswaran, K.

2001-12-01

Europa has attracted much attention as evidence suggests the presence of a liquid ocean beneath this Jupiter moon's frozen crust. Such an environment might be conducive to the origins of life. Since robotic exploration of Europa is being planned, it becomes crucial to prepare for bio-burden reduction of hardware assembled for Europa missions to avoid contamination of Europa's pristine environment. In this study, we examined the microbial diversity of samples collected from two flight-ready circuit boards and their assembly facility. Also, because Jupiter's strong radiation environment may be able to reduce the viable microbial contamination on flight components, we have also studied the effects of radiation on microbial communities found to be associated with the space-flight hardware and/or present in the assembly facility. Surface samples thought to be representative of considerable human contact were collected from two circuit boards and various locations within the assembly facility using polyester swabs (swab samples). Likewise, sterile wipes were used to sample a shelf above the workstation where the circuit boards were assembled and the floor of the facility (wipe samples). The swab and wipe samples were pooled separately and divided into two halves, one of which was irradiated with 1Mrad gamma radiation for 5.5 hours, the other was not irradiated. About 1.2x104 and 6x104 CFUs/m2 cultivable microbes were detected in the swab and wipe samples, respectively. Radiation proved effective in inhibiting the growth of most microbes. Further characterization of the bacterial colonies observed in the irradiated swab and wipe samples is necessary to determine the degree of the radiation resistance. The16S rDNA sequence analysis of the cultivable microbes indicated that the assembly facility consists mostly of the members of actinobacteria, corynebacteria and pseudomonads. However, the swab samples that include the circuit boards were predominantly populated with Bacillus and Staphylococcus. Molecular microbial diversity was also studied by cloning the 16S rDNA PCR fragment from the samples. The non-irradiated swab samples were largely populated by species of Exiguobacter and Bacillus whereas the irradiated swab samples were dominated by Bacillus and E. coli. Radiation damage of microorganisms was also investigated by epifluorescence microscopy. In summary, our study has shown that gamma radiation can inhibit the growth of most of the cultivable microbes, but preliminary results suggest that radiation such as this has little adverse effect on the DNA molecules of these microorganisms.

Method to determine the position-dependant metal correction factor for dose-rate equivalent laser testing of semiconductor devices

DOEpatents

Horn, Kevin M.

2013-07-09

A method reconstructs the charge collection from regions beneath opaque metallization of a semiconductor device, as determined from focused laser charge collection response images, and thereby derives a dose-rate dependent correction factor for subsequent broad-area, dose-rate equivalent, laser measurements. The position- and dose-rate dependencies of the charge-collection magnitude of the device are determined empirically and can be combined with a digital reconstruction methodology to derive an accurate metal-correction factor that permits subsequent absolute dose-rate response measurements to be derived from laser measurements alone. Broad-area laser dose-rate testing can thereby be used to accurately determine the peak transient current, dose-rate response of semiconductor devices to penetrating electron, gamma- and x-ray irradiation.

Trench-parallel flow beneath the nazca plate from seismic anisotropy.

PubMed

Russo, R M; Silver, P G

1994-02-25

Shear-wave splitting of S and SKS phases reveals the anisotropy and strain field of the mantle beneath the subducting Nazca plate, Cocos plate, and the Caribbean region. These observations can be used to test models of mantle flow. Two-dimensional entrained mantle flow beneath the subducting Nazca slab is not consistent with the data. Rather, there is evidence for horizontal trench-parallel flow in the mantle beneath the Nazca plate along much of the Andean subduction zone. Trench-parallel flow is attributale utable to retrograde motion of the slab, the decoupling of the slab and underlying mantle, and a partial barrier to flow at depth, resulting in lateral mantle flow beneath the slab. Such flow facilitates the transfer of material from the shrinking mantle reservoir beneath the Pacific basin to the growing mantle reservoir beneath the Atlantic basin. Trenchparallel flow may explain the eastward motions of the Caribbean and Scotia sea plates, the anomalously shallow bathymetry of the eastern Nazca plate, the long-wavelength geoid high over western South America, and it may contribute to the high elevation and intense deformation of the central Andes.

Imaging the Laguna del Maule Volcanic Field, central Chile using magnetotellurics: Evidence for crustal melt regions laterally-offset from surface vents and lava flows

NASA Astrophysics Data System (ADS)

Cordell, Darcy; Unsworth, Martyn J.; Díaz, Daniel

2018-04-01

Magnetotelluric (MT) data were collected at the Laguna del Maule volcanic field (LdMVF), located in central Chile (36°S, 70.5°W), which has been experiencing unprecedented upward ground deformation since 2007. These data were used to create the first detailed three-dimensional electrical resistivity model of the LdMVF and surrounding area. The resulting model was spatially complex with several major conductive features imaged at different depths and locations around Laguna del Maule (LdM). A near-surface conductor (C1; 0.5 Ωm) approximately 100 m beneath the lake is interpreted as a conductive smectite clay cap related to a shallow hydrothermal reservoir. At 4 km depth, a strong conductor (C3; 0.3 Ωm) is located beneath the western edge of LdM. The proximity of C3 to the recent Pleistocene-to-Holocene vents in the northwest LdMVF and nearby hot springs suggests that C3 is a hydrous (>5 wt% H2O), rhyolitic partial melt with melt fraction >35% and a free-water hydrothermal component. C3 dips towards, and is connected to, a deeper conductor (C4; 1 Ωm). C4 is located to the north of LdM at >8 km depth below surface and is interpreted as a long-lived, rhyolitic-to-andesitic magma reservoir with melt fractions less than 35%. It is hypothesized that the deeper magma reservoir (C4) is providing melt and hydrothermal fluids to the shallower magma reservoir (C3). A large conductor directly beneath the LdMVF is not imaged with MT suggesting that any mush volume beneath LdM must be anhydrous (<2 wt% H2O), low temperature and low melt fraction (<25%) in order to go undetected. The presence of large conductors to the north has important implications for magma dynamics as it suggests that material may have a significant lateral component (>10 km) as it moves from the deep magma reservoir (C4) to create small, ephemeral volumes of eruptible melt (C3). It is hypothesized that there may be a north-south contrast in physical processes affecting the growth of melt-rich zones since major conductors are imaged in the northern LdMVF while no major conductors are detected beneath the southern vents. The analysis and interpretation of features directly beneath the lake is complicated by the surface conductor C1 which attenuates low-frequency signals. The attenuation from C1 does not affect C3 or C4. At 1 km depth directly beneath LdM, a weak conductor (C2; <10 Ωm) is imaged but is not required by the data. Forward modeling tests show that a relatively large (30 km3), high melt fraction (>50%), silicic reservoir with 5 wt% H2O at 2 to 5 km depth beneath the inflation center is not supported by the MT data. However, a smaller (10 km3) eruptible volume could go undetected even with relatively high melt fraction (>50%). The location of large melt regions to the north has important implications for long-term volcanic hazards at LdMVF as well as other volcanoes as it raises the possibility that the vent distribution is not always indicative of the location of deeper source regions of melt.

Nonlinear 1D and 2D waveform inversions of SS precursors and their applications in mantle seismic imaging

NASA Astrophysics Data System (ADS)

Dokht, R.; Gu, Y. J.; Sacchi, M. D.

2016-12-01

Seismic velocities and the topography of mantle discontinuities are crucial for the understanding of mantle structure, dynamics and mineralogy. While these two observables are closely linked, the vast majority of high-resolution seismic images are retrieved under the assumption of horizontally stratified mantle interfaces. This conventional correction-based process could lead to considerable errors due to the inherent trade-off between velocity and discontinuity depth. In this study, we introduce a nonlinear joint waveform inversion method that simultaneously recovers discontinuity depths and seismic velocities using the waveforms of SS precursors. Our target region is the upper mantle and transition zone beneath Northeast Asia. In this region, the inversion outcomes clearly delineate a westward dipping high-velocity structure in association with the subducting Pacific plate. Above the flat part of the slab west of the Japan sea, our results show a shear wave velocity reduction of 1.5% in the upper mantle and 10-15 km depression of the 410 km discontinuity beneath the Changbaishan volcanic field. We also identify the maximum correlation between shear velocity and transition zone thickness at an approximate slab dip of 30 degrees, which is consistent with previously reported values in this region.To validate the results of the 1D waveform inversion of SS precursors, we discretize the mantle beneath the study region and conduct a 2D waveform tomographic survey using the same nonlinear approach. The problem is simplified by adopting the discontinuity depths from the 1D inversion and solving only for perturbations in shear velocities. The resulting models obtained from the 1D and 2D approaches are self-consistent. Low-velocities beneath the Changbai intraplate volcano likely persist to a depth of 500 km. Collectively, our seismic observations suggest that the active volcanoes in eastern China may be fueled by a hot thermal anomaly originating from the mantle transition zone.

A high-density remote reference magnetic variation profile in the Pacific northwest of North America

USGS Publications Warehouse

Hermance, J.F.; Lusi, S.; Slocum, W.; Neumann, G.A.; Green, A.W.

1989-01-01

During the summer of 1985, as part of the EMSLAB Project, Brown University conducted a detailed magnetic variation study of the Oregon Coast Range and Cascades volcanic system along an E-W profile in central Oregon. Comprised of a sequence of 75 remote reference magnetic variation (MV) stations spaced 3-4 km apart, the profile stretched for 225 km from Newport, on the Oregon coast, across the Coast Range, the Willamette Valley, and the High Cascades to a point ??? 50 km east of Santiam Pass. At all of the MV stations, data were collected for short periods (16-100 s), and at 17 of these stations data were also obtained at longer periods (100-1600 s). Data were monitored with a three-component ring core fluxgate magnetometer (Nanotesla), and were recorded with a microcomputer (DEC PDP 11/73) based data acquisition system. A 2-D generalized inversion of the magnetic transfer coefficients over the period range of 16-1600 s indicates four distinct conductors. First, we see the coast effect caused by a large sedimentary wedge offshore. Second, we see the effect of currents flowing in the conductive sediments of the Willamette Valley. Our inversion suggests that the Willamette Valley consists of two electrically distinct features, due perhaps to a horst-like structure imprinted on the valley sediments. Next we note an electric current system centered beneath the High Cascades. This latter feature may be associated with a sediment-filled graben beneath Santiam Pass as suggested by some of the gravity and MT results reported to date. Finally, we detect the presence of a deep conductor at mid-crustal depths which laterally extends westward from beneath the Basin and Range Province, and terminates beneath the western Cascades. One view of this last result is that it appears that modern Basin and Range structure is being imprinted on pre-existing Cascade structure. ?? 1989.

Resistivity structures across the Humboldt River basin, north-central Nevada

USGS Publications Warehouse

Rodriguez, Brian D.; Williams, Jackie M.

2002-01-01

Magnetotelluric data collected along five profiles show deep resistivity structures beneath the Battle Mountain-Eureka and Carlin gold trends in north-central Nevada, which appear consistent with tectonic breaks in the crust that possibly served as channels for hydrothermal fluids. It seems likely that gold deposits along these linear trends were, therefore, controlled by deep regional crustal fault systems. Two-dimensional resistivity modeling of the magnetotelluric data generally show resistive (30 to 1,000 ohm-m) crustal blocks broken by sub-vertical, two-dimensional, conductive (1 to 10 ohmm) zones that are indicative of large-scale crustal fault zones. These inferred fault zones are regional in scale, trend northeast-southwest, north-south, and northwest-southeast, and extend to mid-crustal (20 km) depths. The conductors are about 2- to 15-km wide, extend from about 1 to 4 km below the surface to about 20 km depth, and show two-dimensional electrical structure. By connecting the locations of similar trending conductors together, individual regional crustal fault zones within the upper crust can be inferred that range from about 4- to 10-km wide and about 30- to 150-km long. One of these crustal fault zones coincides with the Battle Mountain-Eureka mineral trend. The interpreted electrical property sections also show regional changes in the resistive crust from south to north. Most of the subsurface in the upper 20 km beneath Reese River Valley and southern Boulder Valley are underlain by rock that is generally more conductive than the subsurface beneath Kelly Creek Basin and northern Boulder Valley. This suggests that either elevated-temperature or high-salinity fluids, alteration, or carbonaceous rocks are more pervasive in the more conductive area (Battle Mountain Heat-Flow High), which implies that the crust beneath these valleys is either more fractured or has more carbonaceous rocks than in the area surveyed along the 41st parallel.

Electrical conductivity anomaly beneath Mare Serenitatis detected by Lunokhod 2 and Apollo 16 magnetometers

NASA Technical Reports Server (NTRS)

Vanian, L. L.; Vnuchkova, T. A.; Egorov, I. V.; Basilevskii, A. T.; Eroshenko, E. G.; Fainberg, E. B.; Dyal, P.; Daily, W. D.

1979-01-01

Magnetic fluctuations measured by the Lunokhod 2 magnetometer in the Bay Le Monnier are distinctly anisotropic when compared to simultaneous Apollo 16 magnetometer data measured 1100 km away in the Descartes highlands. This anisotropy can be explained by an anomalous electrical conductivity of the upper mantle beneath Mare Serenitatis. A model is presented of anomalously lower electrical conductivity beneath Serenitatis and the simultaneous magnetic data from the Lunokhod 2 site at the mare edge and the Apollo 16 site are compared to the numerically calculated model solutions. This comparison indicates that the anisotropic fluctuations can be modeled by a nonconducting layer in the lunar lithosphere which is 150 km thick beneath the highlands and 300 km thick beneath Mare Serenitatis. A decreased electrical conductivity in the upper mantle beneath the mare may be due to a lower temperature resulting from heat carried out the magma source regions to the surface during mare flooding.

Preliminary observations of the behavior of male, flat-tailed horned lizards before and after an off-highway vehicle race in California

USGS Publications Warehouse

Nicolai, N.C.; Lovich, J.E.

2000-01-01

Brains of juvenile gray bats, Myotis grisescens, found dead beneath maternity roosts in two Missouri caves contained lethal concentrations of dieldrin. One colony appeared to be abnormally small, and more dead bats were found a year after the juvenile bats had been collected. This is the first report to link the field mortality of bats directly to insecticide residues acquired through the food chain.

Reconsideration of evolutionary model of the Hawaiian-type volcano: 40Ar/39Ar ages for lavas from deep interior of Oahu Island and alkali basalts from the North Arch volcanic field

NASA Astrophysics Data System (ADS)

Uto, K.; Ishizuka, O.; Garcia, M. O.; Clague, D. A.; Naka, J.

2002-12-01

Growth history of Hawaiian-type volcanoes is typified into four stages: pre-shield, shield-forming, post-shield and rejuvinated. Duration of volcanism from pre-shield to post-shield stage is considered to be at most two million years, and is followed by the rejuvinated-stage after the dormance of one to two million years. There are, however, considerable amount of volcanic products hidden beneath the surface, and the above model may not be real due to the limited observation. US-Japan joint research on Hawaiian volcanism using ROV {\\KAIKO} and submersible {\\SHINKAI6500} of JAMSTEC has revealed many unknown volcanic processes of Hawaii. We challenge the well-established growth model of Hawaiian volcanoes from 40Ar/39Ar dating on rocks collected from the deep root of the submarine cliff of Oahu Island and from the widespread lava field off the coast of Oahu. Northern slope of Oahu Island is a deeply dissected steep wall from the ridge 1,000 m above the sea level to 3,000 m beneath the sea level. We expected to discover the deeper part of volcanic products forming Oahu Island. We obtained 6 40Ar/39Ar ages for tholeiitic lavas collected from 3,000 m to 2,600 m below the sea level. Ages are 5.7 and 6 Ma for two samples from the depth of 2,800 - 3,000 m, 4 Ma for a sample from 2,630 m, 3 Ma for a rock dredged between 2,500 and 2,800m, and 2.2 Ma for a sample from 2,602 m. Ages between 2.2 and 4 Ma are compatible with existing ages on subaerial shield-forming lavas on Koolau and Waianae volcano on Oahu, but ages of 5.7 and 6 Ma are about two million years older. Duplicate analyses gave concordant results and isochron ages have atmospheric 40Ar/36Ar initials. We, therefore, consider that these ages represent eruptive ages of samples. Current results suggest that tholeiitic volcanism forming Oahu Island continued almost 4 million years, which is far longer than ever considered. Considering the 8.7 cm/y of plate velocity, volcanism continued while Oahu Island moved 350 km from the place it was born. This may suggest the dimension of Hawaiian plume if it had been fixed to the earth, or may indicate the some temporal swing of the plume. North Arch volcanic field is a wide-spread flat lava flow field of extremely silica undersaturated alkali basalts existing about 200 km north from the Hawaiian volcanic chain. Six lavas taken by {\\SHINKAI6500} and four samples dredged by USGS are dated. Ages are continuously ranging from 1.4 to 0.5 Ma, suggesting that the volcanism continued at least one million years contemporaneously with rejuvinated-stage volcanism on the islands of Oahu, Niihau, Kauai and Molokai. Chemical compositions of North-Arch lavas are within the variation of these rejuvinated-stage alkali basalts. The similarities in ages and chemistry question the origin of rejuvinated-stage volcanism. These lavas may not be peripheral products of Hawaiian plume, but represent marginal volcanoes of much larger North Arch volcanic field.

Final work plan : investigation of potential contamination at the former CCC/USDA grain storage facility in Hanover, Kansas.

DOE Office of Scientific and Technical Information (OSTI.GOV)

LaFreniere, L. M.; Environmental Science Division

The Commodity Credit Corporation (CCC), an agency of the U.S. Department of Agriculture (USDA), operated a grain storage facility at the northeastern edge of the city of Hanover, Kansas, from 1950 until the early 1970s. During this time, commercial grain fumigants containing carbon tetrachloride were in common use by the grain storage industry to preserve grain in their facilities. In February 1998, trace to low levels of carbon tetrachloride (below the maximum contaminant level [MCL] of 5.0 {micro}g/L) were detected in two private wells near the former grain storage facility at Hanover, as part of a statewide USDA private wellmore » sampling program that was implemented by the Kansas Department of Health and Environment (KDHE) near former CCC/USDA facilities. In April 2007, the CCC/USDA collected near-surface soil samples at 1.8-2 ft BGL (below ground level) at 61 locations across the former CCC/USDA facility. All soil samples were analyzed by the rigorous gas chromatograph-mass spectrometer analytical method (purge-and-trap method). No contamination was found in soil samples above the reporting limit of 10 {micro}g/kg. In July 2007, the CCC/USDA sampled indoor air at nine residences on or adjacent to its former facility to address the residents concerns regarding vapor intrusion. Low levels of carbon tetrachloride were detected at four of the nine homes. Because carbon tetrachloride found in private wells and indoor air at the site might be linked to historical use of fumigants containing carbon tetrachloride at its former grain storage facility, the CCC/USDA is proposing to conduct an investigation to determine the source and extent of the carbon tetrachloride contamination associated with the former facility. This investigation will be conducted in accordance with the intergovernmental agreement between the KDHE and the Farm Service Agency (FSA) of the USDA. The investigation at Hanover will be performed, on behalf of the CCC/USDA, by the Environmental Science Division of Argonne National Laboratory. Argonne is a nonprofit, multidisciplinary research center operated by UChicago Argonne, LLC, for the U.S. Department of Energy (DOE). The CCC/USDA has entered into an interagency agreement with DOE, under which Argonne provides technical assistance to the CCC/USDA with environmental site characterization and remediation at its former grain storage facilities. Seven technical objectives have been proposed for the Hanover investigation. They are as follows: (1) Identify the sources and extent of soil contamination beneath the former CCC/USDA facility; (2) Characterize groundwater contamination beneath the former CCC/USDA facility; (3) Determine groundwater flow patterns; (4) Define the vertical and lateral extent of the groundwater plume outside the former CCC/USDA facility; (5) Evaluate the aquifer and monitor the groundwater system; (6) Identify any other potential sources of contamination that are not related to activities of the CCC/USDA; and (7) Determine whether there is a vapor intrusion problem at the site attributable to the former CCC/USDA facility. The technical objectives will be accomplished in a phased approached. Data collected during each phase will be evaluated to determine whether the subsequent phase is necessary. The KDHE project manager and the CCC/USDA will be contacted during each phase and kept apprised of the results. Whether implementation of each phase of work is necessary will be discussed and mutually agreed upon by the CCC/USDA and KDHE project managers.« less

Qualilty, isotopes, and radiochemistry of water sampled from the Upper Moenkopi Village water-supply wells, Coconino County, Arizona

USGS Publications Warehouse

Carruth, Rob; Beisner, Kimberly; Smith, Greg

2013-01-01

The Hopi Tribe Water Resources Program has granted contracts for studies to evaluate water supply conditions for the Moenkopi villages in Coconino County, Arizona. The Moenkopi villages include Upper Moenkopi Village and the village of Lower Moencopi, both on the Hopi Indian Reservation south of the Navajo community of Tuba City. These investigations have determined that water supplies are limited and vulnerable to several potential sources of contamination, including the Tuba City Landfill and a former uranium processing facility known as the Rare Metals Mill. Studies are ongoing to determine if uranium and other metals in groundwater beneath the landfill are greater than regional groundwater concentrations. The source of water supply for the Upper Moenkopi Village is three public-supply wells. The wells are referred to as MSW-1, MSW-2, and MSW-3 and all three wells obtain water from the regionally extensive N aquifer. The N aquifer is the principal aquifer in this region of northern Arizona and consists of thick beds of sandstone between less permeable layers of siltstone and mudstone. The relatively fine-grained character of the N aquifer inhibits rapid movement of water and large yields to wells. In recent years, water levels have declined in the three public-supply wells, causing concern that the current water supply will not be able to accommodate peak demand and allow for residential and economic growth. Analyses of major ions, nutrients, selected trace metals, stable and radioactive isotopes, and radiochemistry were performed on the groundwater samples from the three public-supply wells to describe general water-quality conditions and groundwater ages in and immediately surrounding the Upper Moenkopi Village area. None of the water samples collected from the public-supply wells exceeded the U.S. Environmental Protection Agency primary drinking water standards. The ratios of the major dissolved ions from the samples collected from MSW-1 and MSW-2 indicate water with a major ion composition of calcium and sulfate. There is no significant vertical distribution of ion concentrations in the samples collected from the upper and lower portion of the water column within the two wells. The samples collected at MSW-3 are higher in sodium and lower in calcium than the samples collected from MSW-1 and MSW-2, and contain a similar sulfate-ion percentage. There is a vertical distribution of ion concentrations in the samples collected from the upper and lower portion of the water column in MSW-3. Groundwater samples from the three water-supply wells analyzed for oxygen-18 and deuterium stable isotopes plot on a local water line that is approximately parallel to the global meteoric water line. Tritium concentrations in samples from MSW-1 and MSW-3 were equal to or less than laboratory detection limits and were interpreted to contain no modern (post-1952) water. Tritium concentration in a sample from the top of the water column at MSW-2 was 0.41 tritium units, indicating that the composition is primarily pre-bomb (pre-1952) water, but may contain a small fraction of post-bomb modern water. The calculated carbon-14 ages of groundwater in MSW-1 and MSW-2, both completed about 140 feet into the Navajo Sandstone, are about 3,000 years before present. The calculated carbon-14 age of groundwater in MSW-3, completed about 240 feet into the Kayenta Formation-Navajo Sandstone transition zone is about 5,000 years before present in the upper portion of the water column and about 8,500 years before present in the lower portion of the water column. The gross alpha radioactivity of samples collected from the three water-supply wells ranged from 5.1 to 9.8 picocuries per liter-less than the U.S. Environmental Protection Agency primary drinking water standard of 15 picocuries per liter. The gross beta radioactivity of samples collected from the wells ranged from 0.9 to 2.8 picocuries per liter and are not considered elevated relative to the U.S. Environmental Protection Agency primary drinking water standard.

The Lithospheric Structure of the Solonker Suture Zone and Adjacent Areas: Crustal Structure Revealed by a High-Resolution Magnetotelluric Study

NASA Astrophysics Data System (ADS)

Ye, Gaofeng; Jin, Sheng; Wei, Wenbo; Jing, Jian'en

2017-04-01

The closure of the Paleo-Asian Ocean along the Solonker Suture Zone (SSZ) during the Late Permian and Triassic represented the final stage in the formation of the Central Asian Orogenic Belt between the Siberian Craton and the North China Craton. In order to better understand the structure and formation of this ancient subduction zone, a high-resolution magnetotelluric (MT) profile was collected with both broadband and long-period MT data. The high resolution mapping of the lithosphere achieved in this study is due to the closely spaced MT stations (2-3 km). With the 2-D resistivity model, a south-dipping conductor was detected and extends through the entire crust. The geometry of this feature provides evidence that a southward directed subduction zone formed the Solonker suture. The enhanced conductivity was interpreted to subducted sulfide-bearing graphitic sediments. The resistive body beneath the northern margin of the North China Craton indicates a thickened lithosphere caused by the southward subduction at this region, and the resistive body beneath the Solonker Suture Zone indicates the subducted oceanic lithosphere. North-dipping low resistivity features were also detected in the crust of both the North China Craton and Central Asian Orogenic Belt, and were interpreted as post-collisional thrust faults. Strong anisotropy was found beneath the suture zone, and can be explained if the high strain rate has rotated the fold axes into the dip direction.

Direct and indirect evidence for earthquakes; an example from the Lake Tahoe Basin, California-Nevada

NASA Astrophysics Data System (ADS)

Maloney, J. M.; Noble, P. J.; Driscoll, N. W.; Kent, G.; Schmauder, G. C.

2012-12-01

High-resolution seismic CHIRP data can image direct evidence of earthquakes (i.e., offset strata) beneath lakes and the ocean. Nevertheless, direct evidence often is not imaged due to conditions such as gas in the sediments, or steep basement topography. In these cases, indirect evidence for earthquakes (i.e., debris flows) may provide insight into the paleoseismic record. The four sub-basins of the tectonically active Lake Tahoe Basin provide an ideal opportunity to image direct evidence for earthquake deformation and compare it to indirect earthquake proxies. We present results from high-resolution seismic CHIRP surveys in Emerald Bay, Fallen Leaf Lake, and Cascade Lake to constrain the recurrence interval on the West Tahoe Dollar Point Fault (WTDPF), which was previously identified as potentially the most hazardous fault in the Lake Tahoe Basin. Recently collected CHIRP profiles beneath Fallen Leaf Lake image slide deposits that appear synchronous with slides in other sub-basins. The temporal correlation of slides between multiple basins suggests triggering by events on the WTDPF. If correct, we postulate a recurrence interval for the WTDPF of ~3-4 k.y., indicating that the WTDPF is near its seismic recurrence cycle. In addition, CHIRP data beneath Cascade Lake image strands of the WTDPF that offset the lakefloor as much as ~7 m. The Cascade Lake data combined with onshore LiDAR allowed us to map the geometry of the WTDPF continuously across the southern Lake Tahoe Basin and yielded an improved geohazard assessment.

Structures of Xishan village landslide in Li County, Sichuan, China, inferred from high-frequency receiver functions of local earthquakes

NASA Astrophysics Data System (ADS)

Wei, Z.; Chu, R.

2017-12-01

Teleseismic receiver function methods are widely used to study the deep structural information beneath the seismic station. However, teleseismic waveforms are difficult to extract the high-frequency receiver function, which are insufficient to constrain the shallow structure because of the inelastic attenuation effect of the earth. In this study, using the local earthquake waveforms collected from 3 broadband stations deployed on the Xishan village landslide in Li County in Sichuan Province, we used the high-frequency receiver function method to study the shallow structure beneath the landslide. We developed the Vp-k (Vp/Vs) staking method of receiver functions, and combined with the H-k stacking and waveform inversion methods of receiver functions to invert the landslide's thickness, S-wave velocity and average Vp/Vs ratio beneath these stations, and compared the thickness with the borehole results. Our results show small-scale lateral variety of velocity structure, a 78-143m/s lower S-wave velocity in the bottom layer and 2.4-3.1 Vp/Vs ratio in the landslide. The observed high Vp/Vs ratio and low S-wave velocity in the bottom layer of the landslide are consistent with low electrical resistivity and water-rich in the bottom layer, suggesting a weak shear strength and potential danger zone in landslide h1. Our study suggest that the local earthquake receiver function can obtain the shallow velocity structural information and supply some seismic constrains for the landslide catastrophe mitigation.

Back-arc rifting at a continental margin: A case study from the Okinawa trough

NASA Astrophysics Data System (ADS)

Arai, R.; Kaiho, Y.; Takahashi, T.; Nakanishi, A.; Fujie, G.; Kodaira, S.; Kaneda, Y.

2014-12-01

The Okinawa trough, a back-arc basin formed behind the Ryukyu arc-trench system, southwest Japan, represents an active rifting zone associated with extension of the continental lithosphere. The basin is located at the southeastern margin of the Eurasian plate and characterized by axial rift valleys with over 1.0 km depth and ~100 km width. Previous studies suggest that the early rifting phase started late Miocene and crustal extension is currently active at a full rate of 30 to 50 mm/yr. Within the basin, numerous active hydrothermal vents are observed, suggesting that the crustal rifting enhances melt/heat transfer from the deep mantle up to the seafloor. However, internal structure beneath the back-arc basin and its relation to the rifting system are little documented. Complex regional tectonic setting, such as active collision in Taiwan to the west, oblique subduction of the Philippine Sea slab, and changing spreading rate along the rift axis, may also have significant influences on the thermal structure and flow within the mantle wedge, but their relative roles in controlling the rifting mode and magmatic supply are still poorly understood. As a step toward filling this gap in knowledge, we started a new 7-year project that consists of four two-dimensional active-source seismic experiments and extensive passive-source seismic observations along the Ryukyu arc. In 2013, active-source seismic data were collected on the first line that crosses the southernmost part of the Ryukyu arc-trench and Okinawa trough at 124-125°E. For refraction/wide-angle reflection analyses, a total of 60 ocean bottom seismographs were deployed with approximately 6 km spacing on a ~390-km-long profile. On the same line, multichannel seismic (MCS) reflection profiling was also carried out. Seismic velocity models obtained by first arrival tomography show that beneath the volcanic arc a thick layer (~10 km) of the middle crust with Vp = 6.0-6.8 km/s is developed, a typical feature in the major volcanic arc in the circum-Pacific region, but such thick layers are not observed beneath the Okinawa trough. Correspondingly, crustal thickness significantly varies: Crust thins from over 20 km beneath the volcanic arc to ~15 km beneath the back-arc basin.

Hydrothermal venting on the flanks of Heard and McDonald islands, southern Indian Ocean

NASA Astrophysics Data System (ADS)

Lupton, J. E.; Arculus, R. J.; Coffin, M.; Bradney, A.; Baumberger, T.; Wilkinson, C.

2017-12-01

Heard Island and the nearby McDonald Islands are two sites of active volcanism associated with the so-called Kerguelen mantle plume or hot spot. In fact, it has been proposed that the Kerguelen hot spot is currently located beneath Heard Island. During its maiden maximum endurance voyage (IN2016_V01), the recently commissioned Australian R/V Investigator conducted a detailed bathymetric and water column survey of the waters around Heard Island and the McDonald Islands as well as other sites on the Kerguelen Plateau. Some 50 hydrographic profiles were completed using the CTD/rosette system equipped with trace metal sampling and a nephelometer for suspended particle concentrations. In addition to the hydrographic profiles, 244 bubble plumes were detected in the vicinity of the Heard and McDonald Islands using the ship's multibeam system. It is thought that the bubble plumes observed on sea knolls and other seafloor surrounding the McDonald Islands are likely hydrothermal in origin, while plumes northeast of Heard Island may be biogenic methane from cold seeps. At 29 of the hydrographic stations water samples for helium isotope measurements were drawn from the CTD rosette and hermetically sealed into copper tubing for subsequent shorebased mass spectrometer and gas chromatograph analysis. In this paper we report results for 3He/4He ratios and CO2 and CH4 concentrations in water samples collected with the CTD/rosette, and discuss how these results are correlated with suspended particle concentrations and temperature anomalies.

Desert Perennial Shrubs Shape the Microbial-Community Miscellany in Laimosphere and Phyllosphere Space.

PubMed

Martirosyan, Varsik; Unc, Adrian; Miller, Gad; Doniger, Tirza; Wachtel, Chaim; Steinberger, Yosef

2016-10-01

Microbial function, composition, and distribution play a fundamental role in ecosystem ecology. The interaction between desert plants and their associated microbes is expected to greatly affect their response to changes in this harsh environment. Using comparative analyses, we studied the impact of three desert shrubs, Atriplex halimus (A), Artemisia herba-alba (AHA), and Hammada scoparia (HS), on soil- and leaf-associated microbial communities. DNA extracted from the leaf surface and soil samples collected beneath the shrubs were used to study associated microbial diversity using a sequencing survey of variable regions of bacterial 16S rRNA and fungal ribosomal internal transcribed spacer (ITS1). We found that the composition of bacterial and fungal orders is plant-type-specific, indicating that each plant type provides a suitable and unique microenvironment. The different adaptive ecophysiological properties of the three plant species and the differential effect on their associated microbial composition point to the role of adaptation in the shaping of microbial diversity. Overall, our findings suggest a link between plant ecophysiological adaptation as a "temporary host" and the biotic-community parameters in extreme xeric environments.

Streptomycin Application Has No Detectable Effect on Bacterial Community Structure in Apple Orchard Soil

PubMed Central

Shade, Ashley; Klimowicz, Amy K.; Spear, Russell N.; Linske, Matthew; Donato, Justin J.; Hogan, Clifford S.; McManus, Patricia S.

2013-01-01

Streptomycin is commonly used to control fire blight disease on apple trees. Although the practice has incited controversy, little is known about its nontarget effects in the environment. We investigated the impact of aerial application of streptomycin on nontarget bacterial communities in soil beneath streptomycin-treated and untreated trees in a commercial apple orchard. Soil samples were collected in two consecutive years at 4 or 10 days before spraying streptomycin and 8 or 9 days after the final spray. Three sources of microbial DNA were profiled using tag-pyrosequencing of 16S rRNA genes: uncultured bacteria from the soil (culture independent) and bacteria cultured on unamended or streptomycin-amended (15 μg/ml) media. Multivariate tests for differences in community structure, Shannon diversity, and Pielou's evenness test results showed no evidence of community response to streptomycin. The results indicate that use of streptomycin for disease management has minimal, if any, immediate effect on apple orchard soil bacterial communities. This study contributes to the profile of an agroecosystem in which antibiotic use for disease prevention appears to have minimal consequences for nontarget bacteria. PMID:23974143

Vertical Drop Testing and Analysis of the Wasp Helicopter Skid Gear

NASA Technical Reports Server (NTRS)

Jackson, Karen E.; Fuchs, Yvonne T.

2007-01-01

This report describes an experimental program to assess the impact performance of a skid gear for use on the Wasp kit-built helicopter, which is marketed by HeloWerks, Inc. of Hampton, Virginia. In total, five vertical drop tests were performed. The test article consisted of a skid gear mounted beneath a steel plate. A seating platform was attached to the upper surface of the steel plate, and two 95th percentile Hybrid III male Anthropomorphic Test Devices (ATDs) were seated on the platform and secured using a four-point restraint system. The test article also included ballast weights to ensure the correct position of the Center-of-Gravity (CG). Twenty-six channels of acceleration data were collected per test at 50,000 samples per second. The five drop tests were conducted on two different gear configurations. The details of these test programs are presented, as well as an occupant injury assessment. Finally, a finite element model of the skid gear test article was developed for execution in LS-DYNA, an explicit nonlinear transient dynamic code, for predicting the skid gear and occupant dynamic responses due to impact.

Estimates of deep percolation beneath native vegetation, irrigated fields, and the Amargosa-River Channel, Amargosa Desert, Nye County, Nevada

USGS Publications Warehouse

Stonestrom, David A.; Prudic, David E.; Laczniak, Randell J.; Akstin, Katherine C.; Boyd, Robert A.; Henkelman, Katherine K.

2003-01-01

The presence and approximate rates of deep percolation beneath areas of native vegetation, irrigated fields, and the Amargosa-River channel in the Amargosa Desert of southern Nevada were evaluated using the chloride mass-balance method and inferred downward velocities of chloride and nitrate peaks. Estimates of deep-percolation rates in the Amargosa Desert are needed for the analysis of regional ground-water flow and transport. An understanding of regional flow patterns is important because ground water originating on the Nevada Test Site may pass through the area before discharging from springs at lower elevations in the Amargosa Desert and in Death Valley. Nine boreholes 10 to 16 meters deep were cored nearly continuously using a hollow-stem auger designed for gravelly sediments. Two boreholes were drilled in each of three irrigated fields in the Amargosa-Farms area, two in the Amargosa-River channel, and one in an undisturbed area of native vegetation. Data from previously cored boreholes beneath undisturbed, native vegetation were compared with the new data to further assess deep percolation under current climatic conditions and provide information on spatial variability.The profiles beneath native vegetation were characterized by large amounts of accumulated chloride just below the root zone with almost no further accumulation at greater depths. This pattern is typical of profiles beneath interfluvial areas in arid alluvial basins of the southwestern United States, where salts have been accumulating since the end of the Pleistocene. The profiles beneath irrigated fields and the Amargosa-River channel contained more than twice the volume of water compared to profiles beneath native vegetation, consistent with active deep percolation beneath these sites. Chloride profiles beneath two older fields (cultivated since the 1960’s) as well as the upstream Amargosa-River site were indicative of long-term, quasi-steady deep percolation. Chloride profiles beneath the newest field (cultivated since 1993), the downstream Amargosa-River site, and the edge of an older field were indicative of recently active deep percolation moving previously accumulated salts from the upper profile to greater depths.Results clearly indicate that deep percolation and ground-water recharge occur not only beneath areas of irrigation but also beneath ephemeral stream channels, despite the arid climate and infrequency of runoff. Rates of deep percolation beneath irrigated fields ranged from 0.1 to 0.5 m/yr. Estimated rates of deep percolation beneath the Amargosa-River channel ranged from 0.02 to 0.15 m/yr. Only a few decades are needed for excess irrigation water to move through the unsaturated zone and recharge ground water. Assuming vertical, one-dimensional flow, the estimated time for irrigation-return flow to reach the water table beneath the irrigated fields ranged from about 10 to 70 years. In contrast, infiltration from present-day runoff takes centuries to move through the unsaturated zone and reach the water table. The estimated time for water to reach the water table beneath the channel ranged from 140 to 1000 years. These values represent minimum times, as they do not take lateral flow into account. The estimated fraction of irrigation water becoming deep percolation averaged 8 to 16 percent. Similar fractions of infiltration from ephemeral flow events were estimated to become deep percolation beneath the normally dry Amargosa-River channel. In areas where flood-induced channel migration occurs at sub-centennial frequencies, residence times in the unsaturated zone beneath the Amargosa channel could be longer. Estimates of deep percolation presented herein provide a basis for evaluating the importance of recharge from irrigation and channel infiltration in models of ground-water flow from the Nevada Test Site.

Ground-water quality in the West Salt River Valley, Arizona, 1996-98: relations to hydrogeology, water use, and land use

USGS Publications Warehouse

Edmonds, Robert J.; Gellenbeck, Dorinda J.

2002-01-01

The U.S. Geological Survey collected and analyzed ground-water samples in the West Salt River Valley from 64 existing wells selected by a stratified-random procedure. Samples from an areally distributed group of 35 of these wells were used to characterize overall ground-water quality in the basin-fill aquifer. Analytes included the principal inorganic constituents, trace constituents, pesticides, and volatile organic compounds. Additional analytes were tritium, radon, and stable isotopes of hydrogen and oxygen. Analyses of replicate samples and blank samples provided evidence that the analyses of the ground-water samples were adequate for interpretation. The median concentration of dissolved solids in samples from the 35 wells was 560 milligrams per liter, which exceeded the U.S. Environmental Protection Agency Secondary Maximum Contaminant Level for drinking water. Eleven of the 35 samples had a nitrate concentration (as nitrogen) that exceeded the U.S. Environmental Protection Agency Maximum Contaminant Level for drinking water of 10 milligrams per liter. Pesticides were detected in eight samples; concentrations were below the Maximum Contaminant Levels. Deethylatrazine was most commonly detected. The pesticides were detected in samples from wells in agricultural or urban areas that have been irrigated. Concentrations of all trace constituents, except arsenic, were less than the Maximum Contaminant Levels. The concentration of arsenic exceeded the Maximum Contaminant Level of 50 micrograms per liter in two samples. Nine monitoring wells were constructed in an area near Buckeye to assess the effects of agricultural land use on shallow ground water. The median concentration of dissolved solids was 3,340 milligrams per liter in samples collected from these wells in August 1997. The nitrate concentration (as nitrogen) exceeded the Maximum Contaminant Level (10 milligrams per liter) in samples from eight of the nine monitoring wells in August 1997 and again in February 1998. Analyses of all samples collected from the monitoring wells indicated low concentrations of pesticides and volatile organic compounds. The most frequently detected pesticides were deethylatrazine and atrazine. Trichloromethane (chloroform) and tetrachloroethene (PCE) were the most frequently detected volatile organic compounds in the monitoring wells. Two compounds [dieldrin and 1,1-dichloro-2,2-bis(p-dichlorodiphenyl)ethylene (DDE)], decomposition products of two banned pesticides, aldrin and dichlorodiphenylethylene (DDT), were detected at low concentrations in samples analyzed for the agricultural land-use study. In the West Salt River Valley, a high concentration of the heavier oxygen isotope?oxygen-18?in ground water generally indicates effects of evaporation on recharge water from irrigation. Wells in undeveloped areas and wells that have openings beneath a confining bed generally yield ground water that is free of the effects of irrigation seepage. Samples from these wells did not contain detectable concentrations of pesticides. The median concentrations of nitrate (as nitrogen) and dissolved solids in samples from wells in undeveloped areas were 1.7 milligrams per liter and 257 milligrams per liter, respectively. The median concentrations of nitrate (as nitrogen) and dissolved solids in samples from wells that yield water from below confining beds were 2.0 and 747 milligrams per liter, respectively.

Improved DESI-MS Performance using Edge Sampling and aRotational Sample Stage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kertesz, Vilmos; Van Berkel, Gary J

2008-01-01

The position of the surface to be analyzed relative to the sampling orifice or capillary into the mass spectrometer has been known to dramatically affect the observed signal levels in desorption electrospray ionization mass spectrometry (DESIMS). In analyses of sample spots on planar surfaces, DESI-MS signal intensities as much as five times greater were routinely observed when the bottom of the sampling capillary was appropriately positioned beneath the surface plane ( edge sampling") compared to when the capillary just touched the surface. To take advantage of the optimum "edge sampling" geometry and to maximize the number of samples that couldmore » be analyzed in this configuration, a rotational sample stage was integrated into a typical DESI-MS setup. The rapid quantitative determination of caffeine in two diet sport drinks (Diet Turbo Tea, Speed Stack Grape) spiked with an isotopically labeled internal standard demonstrated the utility of this approach.« less

Soil microbial activities beneath Stipa tenacissima L. and in surrounding bare soil

NASA Astrophysics Data System (ADS)

Novosadová, I.; Ruiz Sinoga, J. D.; Záhora, J.; Fišerová, H.

2010-05-01

Open steppes dominated by Stipa tenacissima L. constitute one of the most representative ecosystems of the semi-arid zones of Eastern Mediterranean Basin (Iberian Peninsula, North of Africa). These steppes show a higher degree of variability in composition and structure. Ecosystem functioning is strongly related to the spatial pattern of grass tussocks. Soils beneath S. tenacissima grass show higher fertility and improved microclimatic conditions, favouring the formation of "resource islands" (Maestre et al., 2007). On the other hand in "resource islands" and in surrounding bare soil exists the belowground zone of influence. The competition for water and resources between plants and microorganisms is strong and mediated trough an enormous variety of exudates and resource depletion intended to regulate soil microbial communities in the rhizosphere, control herbivory, encourage beneficial symbioses, and change chemical and physical properties in soil (Pugnaire et Armas, 2008). Secondary compounds and allelopathy restrict other species growth and contribute to patchy plant distribution. Active root segregation affects not only neighbourś growth but also soil microbial activities. The objective of this study was to assess the effect of Stipa tenacissima on the key soil microbial activities under controlled incubation conditions (basal and potential respiration; net nitrogen mineralization). The experimental plots were located in the province Almería in Sierra de los Filabres Mountains near the village Gérgal (southeast Spain) in the small catchment which is situated between 1090 - 1165 m a.s.l. The area with extent of 82 000 m2 is affected by soil degradation. The climate is semiarid Mediterranean. The mean annual rainfall is of about 240 mm mostly concentrated in autumn and spring. The mean annual temperature is 13.9° C. The studied soil has a loam to sandy clay texture and is classified as Lithosol (FAO-ISRIC and ISSS, 1998). The vegetation of these areas is an open steppe dominated by Stipa tenacissima. In February 2009 representative soil samples from the top 10 cm were taken beneath grass tussock and from bare soil. Soil samples in three replicates were incubated after rewetting with distilled water (basal microbial activities) and after rewetting with the glucose solution and with the mixture of glucose and peptone solution (potential microbial activities). The CO2, C2H4 evolved under controlled conditions (60% WHC, 24°C) during a 37-day aerobic incubation were determined. Ammonia and nitrate nitrogen were estimated in percolates after simulated rainfall (on the 16th day of incubation) and in the incubated soil samples at the end of incubation. Net ammonification and net nitrification rates were determined by subtracting initial soil mineral N from both mineral N in percolates plus final mineral N contents at 37th day. Basal, potential microbial respiration and net nitrification in the soils beneath S. tenacissima were, in general, not significantly different from the bare soils. The differences between plant-covered soil and bare soil in cumulative values of CO2 production and in amounts of accumulated NO3--N (net nitrification) were less than ± 10%. Greater differences were found in the net ammonification, which were higher beneath S. tenacissima, mainly in the control (basal activities) variant (about 38 %). Significantly less ethylene produced by microbial activity in soils beneath S. tenacissima after the addition of glucose indicates the dependence of rhizospheric microbial communities on available carbon compounds mainly from root exudates. It can be concluded, similarly as published Goberna et al., (2007), that the distribution of soil microbial properties in semi-arid Mediterranean ecosystems is not necessarily associated with the patchy plant distribution and that some microbial activities characteristics can be unexpectedly homogenous.

Advective transport of CO2 in permeable media induced by atmospheric pressure fluctuations: 2. Observational evidence under snowpacks

Treesearch

W. J. Massman; J. M. Frank

2006-01-01

Meadow and forest CO2 amounts sampled beneath an approximately meter deep (steady state) snowpack at a subalpine site in southern Rocky Mountains of Wyoming are observed to vary by nearly 200 ppm over periods ranging from 4 to 15 days. This work employs the model of periodic, pressure-induced, advective transport in permeable media developed in...

Mantle Water Contents Beneath the Rio Grande Rift (NM, USA): FTIR Analysis of Rio Puerco and Kilbourne Hole Peridotite Xenoliths

NASA Technical Reports Server (NTRS)

Schaffer, L. A.; Peslier, A. H.; Brandon, A.; Selverstone, J.

2015-01-01

Peridotite xenoliths from the Rio Grande Rift (RGR) are being analyzed for H (sub 2) O contents by FTIR (Fourier Transform Infrared) as well as for major and trace element compositions. Nine samples are from the Rio Puerco Volcanic Field (RP) which overlaps the central RGR and southeastern Colorado Plateau; seventeen samples are from Kilbourne Hole (KH) in the southern RGR. Spinel Cr# (Cr/(Cr+Al)) (0.08-0.46) and olivine Mg# (Mg/(Mg plus Fe)) (0.883-0.911) of all RGR samples fall within the olivine-spinel mantle array from [1], an indicator that peridotites are residues of partial melting. Pyroxene H (sub 2) O in KH correlate with bulk rock and pyroxene Al (sub 2) O (sub 3).The KH clinopyroxene rare earth element (REE) variations fit models of 0-13 percent fractional melting of a primitive upper mantle. Most KH peridotites have bulk-rock light REE depleted patterns, but five are enriched in light REEs consistent with metasomatism. Variation in H (sub 2) O content is unrelated to REE enrichment. Metasomatism is seen in RP pyroxenite xenoliths [2] and will be examined in the peridotites studied here. Olivine H (sub 2) O contents are low (less than or equal to 15 parts per million), and decrease from core to rim within grains. This is likely due to H loss during xenolith transport by the host magma [3]. Diffusion models of H suggest that mantle H (sub 2) O contents are still preserved in cores of KH olivine, but not RP olivine. The average H (sub 2) O content of Colorado Plateau clinopyroxene (670 parts per million) [4] is approximately 300 parts per million higher than RGR clinopyroxene (350 parts per million). This upholds the hypothesis that hydration-induced lithospheric melting occurred during flat-slab subduction of the Farallon plate [5]. Numerical models indicate hydration via slab fluids is possible beneath the plateau, approximately 600 kilometers from the paleo-trench, but less likely approximately 850 kilometers away beneath the rift [6].

KSC-2012-3091

NASA Image and Video Library

2012-05-26

CAPE CANAVERAL, Fla. - Teams taking part in NASA's Lunabotics Mining Competition gather inside the Apollo/Saturn V Center at Kennedy Space Center Visitor Complex in Florida for the awards ceremony at the end of the event. They are seated beneath the first stage of the Saturn V rocket that carried astronauts to the moon. The competition challenged university students to build machines that could collect soil such as the material found on the moon. Working inside the Caterpillar LunArena, the robotic craft dug soil that simulated lunar material. The event was judged by a machine's abilities to collect the soil, its design and operation, size, dust tolerance and its level of autonomy. Photo credit: NASA/Jim Grossmann

The mantle transition zone beneath Antarctica: Evidence for thermal upwellings and hydration

NASA Astrophysics Data System (ADS)

Nyblade, Andrew; Emry, Erica; Hansen, Samantha; Julia, Jordi; Anandakrishnan, Sridhar; Aster, Richard; Wiens, Douglas; Huerta, Audrey; Wilson, Terry

2015-04-01

West Antarctica has experienced abundant Cenozoic volcanism, and it is suspected that the region is influenced by upwelling thermal plumes from the lower mantle; however this has not yet been verified, because seismic tomography results are not well resolved at mantle transition zone (MTZ) depths. We use P-wave receiver functions (PRFs) from temporary and permanent arrays throughout Antarctica, including the Antarctic POLENET, TAMNET, TAMSEIS, and GAMSEIS arrays, to explore the characteristics of the MTZ beneath the continent. We obtained PRFs for earthquakes occurring at 30-90° with Mb>5.5 using a time-domain iterative deconvolution method filtered with a Gaussian-width of 0.5 and 1.0, corresponding to frequencies less than ~0.24 Hz and ~0.48 Hz, respectively. We combine P receiver functions as single-station and as common conversion point stacks and migrate them to depth using the ak135 1-d velocity model. Results from West Antarctica suggest that the thickness of the MTZ varies throughout the region with thinning beneath the Ruppert Coast of Marie Byrd Land and beneath the Bentley Subglacial Trench and Whitmore Mountains. Also, prominent negative peaks are detected above the transition zone beneath much of West Antarctica and may be evidence for water-induced partial melt above the MTZ. Preliminary results from single-station stacks for the mantle transition zone beneath East Antarctica suggests that one section of East Antarctica, off of the South Pole may have slightly thinned transition zone. Results are forthcoming from the mantle transition zone beneath Victoria Land and the Northern Transantarctics. We propose that the MTZ beneath parts of West Antarctica and possibly also beneath one region of East Antarctica, is hotter than average, possibly due to material upwelling from the lower mantle. Furthermore, we propose that the transition zone beneath much of West Antarctica is water-rich and that upward migration of hydrated material results in formation of a partial melt layer above the MTZ.

Mercury in forest mushrooms and topsoil from the Yunnan highlands and the subalpine region of the Minya Konka summit in the Eastern Tibetan Plateau.

PubMed

Falandysz, Jerzy; Saba, Martyna; Liu, Hong-Gao; Li, Tao; Wang, Ji-Peng; Wiejak, Anna; Zhang, Ji; Wang, Yuan-Zhong; Zhang, Dan

2016-12-01

This study aimed to investigate and discuss the occurrence and accumulation of mercury in the fruiting bodies of wild-growing fungi (Macromycetes) collected from montane forests in two regions of southwestern China with differences in soil geochemistry, climate and geographical conditions. Fungal mycelia in soils of the subalpine region of the Minya Konka (Gongga Mountain) in Sichuan and in the highlands of Yunnan efficiently accumulated mercury in fruiting bodies (mushrooms). The examined sites in Yunnan with highly mineralized red and yellow soils showed Hg contents ranging from 0.066 to 0.28 mg kg -1 dry biomass (db) which is roughly similar to the results obtained for samples collected from sites with dark soils relatively rich in organic matter from a remote, the subalpine region of Minya Konka. Due to the remoteness of the subalpine section of Minya Konka, as well as its elevation and climate, airborne mercury from long-range transport could be deposited preferentially on the topsoil and the Hg levels determined in soil samples taken beneath the fruiting bodies were up to 0.48 mg kg -1 dry matter. In Yunnan, with polymetallic soils (Circum-Pacific Mercuriferous Belt), Amanita mushrooms showed mercury in caps of fruiting bodies of up to 7.3 mg kg -1 dry biomass. Geogenic Hg from the mercuriferous belt seems to be the overriding source of mercury accumulated in mushrooms foraged in the regions of Yunnan, while long-range atmospheric transport and subsequent deposition are the mercury sources for specimens foraged in the region of Minya Konka.

Melatonin secretion and puberty in female lambs exposed to environmental electric and magnetic fields

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, J.M. Jr.; Stormshak, F.; Thompson, J.M.

This study determined whether chronic exposure of female lambs to the electric and magnetic fields (EMF) of a high voltage transmission line can alter pineal secretion of melatonin and the normal occurrence of puberty. Twenty female Suffolk lambs were assigned randomly in equal numbers to a control and a treatment group. Treatment from 2 to 10 mo of age consisted of continuous exposure within the electrical environment of a 500-kV transmission line (mean electric field 6 kV/m, mean magnetic field 40 mG). Treated lambs were penned directly beneath the transmission line; control lambs were maintained in a pen of similarmore » construction 229 m from the line where EMF were at ambient levels (mean electric field < 10 V/m, mean magnetic field < 0.3 mG). Melatonin was analyzed by RIA in serum of blood samples collected at 0.5-3-h intervals over eight 48-h periods. To assess attainment of puberty, serum concentrations of progesterone were determined by RIA from blood samples collected twice weekly beginning at 19 wk of age. Concentrations of circulating melatonin in control and treated lambs were low during daylight hours and increased during nighttime hours. The characteristic pattern of melatonin secretion during nighttime (amplitude, phase, and duration) did not differ between control and treatment groups. Age at puberty and number of subsequent estrous cycles also did not differ between groups. These data suggest that chronic exposure of developing female sheep to 60-Hz environmental EMF does not affect the mechanisms underlying the generation of the circadian pattern of melatonin secretion or the mechanisms involved in the onset of reproductive activity.« less

Water-quality assessment of the Delmarva Peninsula, Delaware, Maryland, and Virginia; effects of agricultural activities on, and distribution of, nitrate and other inorganic constituents in the surficial aquifer

USGS Publications Warehouse

Hamilton, P.A.; Denver, J.M.; Phillips, P.J.; Shedlock, R.J.

1993-01-01

Agricultural applications of inorganic fertilizers and manure have changed the natural chemical com- position of water in the surficial aquifer through- out the Delmarva Peninsula. Nitrate, derived from nitrification of ammonia in inorganic fertilizers and manure, is the dominant anion in agricultural areas. Concentrations of nitrate in 185 water samples collected in agricultural areas ranged from 0.4 to 48 mg/L as nitrogen, with a median concen- tration of 8.2 mg/L as nitrogen. Nitrate concen- trations exceeded the U.S. Environmental Protection Agency's maximum contaminant level for drinking water of 10 mg/L as nitrogen in about 33% of the 185 water samples. Groundwater affected by agricultural activities contains significantly higher concentrations of dissolved constituents than does natural groundwater. Concentrations of calcium and magnesium are higher because of liming of soils, and concentrations of potassium and chloride are higher because of applications of potash, a supple- ment to the nitrogen-based fertilizers. Alkalinity concentrations commonly are decreased because the bicarbonate ion is consumed in buffering reactions with acid that is produced during nitrification. Effects of agricultural activities on groundwater quality are not limited to the near-surface parts of the aquifer underlying farm fields. Elevated concentrations are common in aerobic water at or near the base of the aquifer, 80 to 100 ft below land surface. The median concentration of nitrate in water beneath agricultural areas collected from 24 wells deeper than 80 ft below land surface was 8.5 mg/L as nitrogen, and concentrations in 9 of these water samples exceeded the maximum contaminant level. Regional variations in concentrations of nitrate and other agriculture related constituents in the surficial aquifer in the Delmarva Peninsula depend on a number of factors that include geomorphology, geology, soils, land use, and groundwater-flow patterns. (USGS)

Contaminant exposure of barn swallows nesting on Bayou d'Inde, Calcasieu Estuary, Louisiana, USA.

USGS Publications Warehouse

Custer, T.W.; Custer, Christine M.; Goatcher, B.L.; Melancon, M.J.; Matson, C.W.; Bickham, J.W.

2006-01-01

Current and historical point source discharges, storm water runoff, and accidental spills have contaminated the water, sediment, and biota within the Calcasieu Estuary in southwestern Louisiana. In 2003, barn swallow (Hirundo rustica) eggs and nestlings were collected beneath two bridges that cross Bayou d'Inde, the most contaminated waterway within the Calcasieu Estuary. Samples were also collected from a bridge over Bayou Teche, a reference site in south central Louisiana. Polychlorinated biphenyl (PCB) concentrations in barn swallow eggs and nestlings were significantly higher at the downstream site on Bayou d'Inde (2.8 micro g/g PCBs in eggs and 1.5 micro g/g PCBs in nestlings) than at the other two sites (< 0.2 micro g/g PCBs in eggs and nestlings at both sites). Ethoxyresorufin-O-dealkylase activity in nestling livers was significantly higher at the downstream site on Bayou d'Inde (50 pmol/min/mg) compared to the other two locations (24 pmol/min/mg, each), probably because of exposure to PCBs. Polychlorinated dibenzo-p-dioxin and polychlorinated dibenzofuran concentrations in eggs and polycyclic aromatic hydrocarbons in nestlings were at background concentrations at all sites. Trace element concentrations in barn swallow eggs and nestling livers were at background levels and did not differ among the three sites. A biomarker of DNA damage did not differ among sites.

Contaminant exposure of barn swallows nesting on Bayou d'Inde, Calcasieu Estuary, Louisiana, USA

USGS Publications Warehouse

Custer, T.W.; Custer, Christine M.; Goatcher, B.L.; Melancon, M.J.; Matson, C.W.; Bickham, J.W.

2006-01-01

Current and historical point source discharges, storm water runoff, and accidental spills have contaminated the water, sediment, and biota within the Calcasieu Estuary in southwestern Louisiana. In 2003, barn swallow (Hirundo rustica) eggs and nestlings were collected beneath two bridges that cross Bayou d'Inde, the most contaminated waterway within the Calcasieu Estuary. Samples were also collected from a bridge over Bayou Teche, a reference site in south central Louisiana. Polychlorinated biphenyl (PCB) concentrations in barn swallow eggs and nestlings were significantly higher at the downstream site on Bayou d'Inde (2.8 mu g/g PCBs in eggs and 1.5 mu g/g PCBs in nestlings) than at the other two sites (< 0.2 mu g/g PCBs in eggs and nestlings at both sites). Ethoxyresorufin-O-dealkylase activity in nestling livers was significantly higher at the downstream site on Bayou d'Inde (50 pmol/min/mg) compared to the other two locations (24 pmol/min/mg, each), probably because of exposure to PCBs. Polychlorinated dibenzo-p-dioxin and polychlorinated dibenzofuran concentrations in eggs and polycyclic aromatic hydrocarbons in nestlings were at background concentrations at all sites. Trace element concentrations in barn swallow eggs and nestling livers were at background levels and did not differ among the three sites. A biomarker of DNA damage did not differ among sites.

Karst Groundwater Hydrologic Analyses Based on Aerial Thermography

NASA Technical Reports Server (NTRS)

Campbell, C. Warren; Keith, A. G.

2000-01-01

On February 23, 1999, thermal imagery of Marshall Space Flight Center, Alabama was collected using an airborne thermal camera. Ground resolution was I in. Approximately 40 km 2 of thermal imagery in and around Marshall Space Flight Center (MSFC) was analyzed to determine the location of springs for groundwater monitoring. Subsequently, forty-five springs were located ranging in flow from a few ml/sec to approximately 280 liter/sec. Groundwater temperatures are usually near the mean annual surface air temperature. On thermography collected during the winter, springs show up as very warm spots. Many of the new springs were submerged in lakes, streams, or swamps; consequently, flow measurements were difficult. Without estimates of discharge, the impacts of contaminated discharge on surface streams would be difficult to evaluate. An approach to obtaining an estimate was developed using the Environmental Protection Agency (EPA) Cornell Mixing Zone Expert System (CORMIX). The thermography was queried to obtain a temperature profile down the center of the surface plume. The spring discharge was modeled with CORMIX, and the flow adjusted until the surface temperature profile was matched. The presence of volatile compounds in some of the new springs also allowed MSFC to unravel the natural system of solution cavities of the karst aquifer. Sampling results also showed that two springs on either side of a large creek had the same water source so that groundwater was able to pass beneath the creek.

Nitrate in groundwater of the United States, 1991-2003

USGS Publications Warehouse

Burow, Karen R.; Nolan, Bernard T.; Rupert, Michael G.; Dubrovsky, Neil M.

2010-01-01

An assessment of nitrate concentrations in groundwater in the United States indicates that concentrations are highest in shallow, oxic groundwater beneath areas with high N inputs. During 1991-2003, 5101 wells were sampled in 51 study areas throughout the U.S. as part of the U.S. Geological Survey National Water-Quality Assessment (NAWQA) program. The well networks reflect the existing used resource represented by domestic wells in major aquifers (major aquifer studies), and recently recharged groundwater beneath dominant land-surface activities (land-use studies). Nitrate concentrations were highest in shallow groundwater beneath agricultural land use in areas with well-drained soils and oxic geochemical conditions. Nitrate concentrations were lowest in deep groundwater where groundwater is reduced, or where groundwater is older and hence concentrations reflect historically low N application rates. Classification and regression tree analysis was used to identify the relative importance of N inputs, biogeochemical processes, and physical aquifer properties in explaining nitrate concentrations in groundwater. Factors ranked by reduction in sum of squares indicate that dissolved iron concentrations explained most of the variation in groundwater nitrate concentration, followed by manganese, calcium, farm N fertilizer inputs, percent well-drained soils, and dissolved oxygen. Overall, nitrate concentrations in groundwater are most significantly affected by redox conditions, followed by nonpoint-source N inputs. Other water-quality indicators and physical variables had a secondary influence on nitrate concentrations.

Super-deep low-velocity layer beneath the Arabian plate

NASA Astrophysics Data System (ADS)

Vinnik, L.; Ravi Kumar, M.; Kind, R.; Farra, V.

2003-04-01

S and P receiver functions reveal indications of a low S velocity layer at 350-410 km depths beneath the Arabian plate. A similar layer was previously found beneath the Kaapvaal craton in southern Africa and Tunguska basin of the Siberian platform. We hypothesize, that the boundary at 350 km depth may separate dry mantle root of the Arabian plate from the underlying wet mantle layer. This boundary is not found beneath the Gulf of Aden, where the root is destroyed by sea-floor spreading.

Imaging Canary Island hotspot material beneath the lithosphere of Morocco and southern Spain

NASA Astrophysics Data System (ADS)

Miller, Meghan S.; O'Driscoll, Leland J.; Butcher, Amber J.; Thomas, Christine

2015-12-01

The westernmost Mediterranean has developed into its present day tectonic configuration as a result of complex interactions between late stage subduction of the Neo-Tethys Ocean, continental collision of Africa and Eurasia, and the Canary Island mantle plume. This study utilizes S receiver functions (SRFs) from over 360 broadband seismic stations to seismically image the lithosphere and uppermost mantle from southern Spain through Morocco and the Canary Islands. The lithospheric thickness ranges from ∼65 km beneath the Atlas Mountains and the active volcanic islands to over ∼210 km beneath the cratonic lithosphere in southern Morocco. The common conversion point (CCP) volume of the SRFs indicates that thinned lithosphere extends from beneath the Canary Islands offshore southwestern Morocco, to beneath the continental lithosphere of the Atlas Mountains, and then thickens abruptly at the West African craton. Beneath thin lithosphere between the Canary hot spot and southern Spain, including below the Atlas Mountains and the Alboran Sea, there are distinct pockets of low velocity material, as inferred from high amplitude positive, sub-lithospheric conversions in the SRFs. These regions of low seismic velocity at the base of the lithosphere extend beneath the areas of Pliocene-Quaternary magmatism, which has been linked to a Canary hotspot source via geochemical signatures. However, we find that this volume of low velocity material is discontinuous along strike and occurs only in areas of recent volcanism and where asthenospheric mantle flow is identified with shear wave splitting analyses. We propose that the low velocity structure beneath the lithosphere is material flowing sub-horizontally northeastwards beneath Morocco from the tilted Canary Island plume, and the small, localized volcanoes are the result of small-scale upwellings from this material.

Constraining the Size and Depth of a Shallow Crustal Magma Body at Newberry Volcano Using P-Wave Tomography and Finite-Difference Waveform Modeling

NASA Astrophysics Data System (ADS)

Beachly, M. W.; Hooft, E. E.; Toomey, D. R.; Waite, G. P.

2011-12-01

Imaging magmatic systems improves our understanding of magma ascent and storage in the crust and contributes to hazard assessment. Seismic tomography reveals crustal magma bodies as regions of low velocity; however the ability of delay-time tomography to detect small, low-velocity bodies is limited by wavefront healing. Alternatively, crustal magma chambers have been identified from secondary phases including P and S wave reflections and conversions. We use a combination of P-wave tomography and finite-difference waveform modeling to characterize a shallow crustal magma body at Newberry Volcano, central Oregon. Newberry's eruptions are silicic within the central caldera and mafic on its periphery suggesting a central silicic magma storage system. The system may still be active with a recent eruption ~1300 years ago and a drill hole temperature of 256° C at only 932 m depth. A low-velocity anomaly previously imaged at 3-5 km beneath the caldera indicates either a magma body or a fractured pluton. With the goal of detecting secondary arrivals from a magma chamber beneath Newberry Volcano, we deployed a line of densely-spaced (~300 m), three-component seismometers that recorded a shot of opportunity from the High Lava Plains Experiment in 2008. The data record a secondary P-wave arrival originating from beneath the caldera. In addition we combine travel-time data from our 2008 experiment with data collected in the 1980's by the USGS for a P-wave tomography inversion to image velocity structure to 6 km depth. The inversion includes 16 active sources, 322 receivers and 1007 P-wave first arrivals. The tomography results reveal a high-velocity, ring-like anomaly beneath the caldera ring faults to 2 km depth that surrounds a shallow low-velocity region. Beneath 2.5 km high-velocity anomalies are concentrated east and west of the caldera. A central low-velocity body lies below 3 km depth. Tomographic inversions of synthetic data suggest that the central low-velocity body beneath 3 km depth is not well resolved and that, for example, an unrealistically large low-velocity body with a volume up to 72 km3 at 40% velocity reduction (representing 30±7% partial melt) could be consistent with the observed travel-times. We use the tomographically derived velocity structure to construct 2D finite difference models and include synthetic low-velocity bodies in these models to test various magma chamber geometries and melt contents. Waveform modeling identifies the observed secondary phase as a transmitted P-wave formed by delaying and focusing P-wave energy through the low-velocity region. We will further constrain the size and shape of the low-velocity region by comparing arrival times and amplitudes of observed and synthetic primary and secondary phases. Secondary arrivals provide compelling evidence for an active crustal magmatic system beneath Newberry volcano and demonstrate the ability of waveform modeling to constrain the nature of magma bodies beyond the limits of seismic tomography.

Shield volcanism and lithospheric structure beneath the Tharsis plateau, Mars

NASA Technical Reports Server (NTRS)

Blasius, K. R.; Cutts, J. A.

1976-01-01

The heights of four great shield volcanoes, when interpreted as reflecting the local hydrostatic head on a common source of upwelling magma, provide significant constraints on models of lithospheric structure beneath the Tharsis plateau. If Bouguer gravity anomalies are modeled in terms of a variable thickness crust, and a two-component (crust/mantle) earth-like structure is assumed for the Martian lithosphere, the derived model lithosphere beneath the Tharsis plateau has the following properties: (1) the upper low-density 'crustal' component is thickened beneath the Tharsis plateau; (2) the lower high-density 'mantle' component is thinned beneath the Tharsis plateau; and (3) there is a net gradient on the base of the Martian lithosphere directed downward away from beneath the summit of the Tharsis plateau. A long history of magmatic intrusion is hypothesized to have been the cause of the updoming of the Tharsis plateau and the maintenance of the plateau in a state of only partial compensation.

P-wave velocity structure beneath the northern Antarctic Peninsula

NASA Astrophysics Data System (ADS)

Park, Y.; Kim, K.; Jin, Y.

2010-12-01

We have imaged tomographically the tree-dimensional velocity structure of the upper mantle beneath the northern Antarctic Peninsula using teleseismic P waves. The data came from the seven land stations of the Seismic Experiment in Patagonia and Antarctica (SEPA) campaigned during 1997-1999, a permanent IRIS/GSN station (PMSA), and 3 seismic stations installed at scientific bases, Esperanza (ESPZ), Jubany (JUBA), and King Sejong (KSJ), in South Shetland Islands. All of the seismic stations are located in coast area, and the signal to noise ratios (SNR) are very low. The P-wave model was inverted from 95 earthquakes resulting in 347 ray paths with P- and PKP-wave arrivals. The inverted model shows a strong low velocity anmaly beneath the Bransfield Strait, and a fast anomaly beneath the South Shetland Islands. The low velocity anomaly beneath the Bransfield might be due to a back arc extension, and the fast velocity anomaly beneath the South Shetland Islands could indicates the cold subducted slab.

Pulling the rug out from under California: Seismic images of the Mendocino Triple Junction region

USGS Publications Warehouse

Tréhu, Anne M.

1995-01-01

In 1993 and 1994 a network of large-aperture seismic profiles was collected to image the crustal and upper-mantle structure beneath northern California and the adjacent continental margin. The data include approximately 650 km of onshore seismic refraction/reflection data, 2000 km of off-shore multichannel seismic (MCS) reflection data, and simultaneous onshore and offshore recording of the MCS airgun source to yield large-aperture data. Scientists from more than 12 institutions were involved in data acquisition.

Proceedings of West Coast Regional Coastal Design Conference Held on 7-8 November 1985 at Oakland, California.

DTIC Science & Technology

1986-04-01

Lon- don, 53 2p. Yancey, T.E. and Lee, J.W. 1972. Major heavy mineral assemblages and heavy mineral provinces of the central California Coast Region...sites have been collected. A data base and a user-friendly retrieval system have been de - veloped and are presently undergoing evaluation before they are...Continental Margin The tectonic evolution of the Oregon coastline appears to be controlled at present by the underthrusting of the Juan de Fuca plate beneath

Combined Effect of Reduced Band Number and Increased Bandwidth on Shallow Water Remote Sensing: The Case of WorldView 2

DTIC Science & Technology

2013-05-01

shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number...functions ( BRDF ) were compared with measurements made just beneath the water’s surface. In Case I water, the set of simulations that varied the particle...scattering phase function depending on chlorophyll concentration agreed more closely with the data than other models . In Case II water, however, the

Selected natural attenuation monitoring data, Operable Unit 1, Naval Undersea Warfare Center, Division Keyport, Washington, June 2001

USGS Publications Warehouse

Dinico, Richard Steven

2003-01-01

Previous investigations have shown that natural attenuation and biodegradation of chlorinated volatile organic compounds (CVOCs) are substantial in shallow ground water beneath the 9-acre former landfill at Operable Unit 1 (OU 1), Naval Undersea Warfare Center (NUWC), Division Keyport, Washington. The U.S. Geological Survey (USGS) has continued to monitor ground-water geochemistry to assure that conditions remain favorable for contaminant biodegradation. This report presents the ground-water geochemical and selected CVOC data collected at OU 1 by the USGS during June 11-14, 2001 in support of the long-term monitoring for natural attenuation. Overall, the June 2001 data indicate that redox conditions in the upper aquifer remain favorable for reductive dechlorination of CVOCs because strongly reducing conditions persisted beneath much of the former landfill. Redox conditions in the intermediate aquifer down gradient of the landfill appear to have become more favorable for reductive dechlorination because June 2001 dissolved hydrogen concentrations indicated strongly reducing conditions there for the first time. Although changes in redox conditions were observed at certain wells during 2001, a longer monitoring period is needed to ascertain if phytoremediation activities are affecting the ground-water chemistry. A minor change to future monitoring is proposed. Filtered organic carbon (previously referred to as dissolved, and defined as that which passes through a 0.45-micrometer membrane filter) should be analyzed in the future rather than unfiltered (previously referred to as total) organic carbon because the filtered analysis may be a better measure of bioavailable organic carbon. Unfiltered and filtered organic carbon data were collected during June 2001 for comparison. Filtered organic carbon data collected in the future could be reasonably compared with historical unfiltered organic carbon data by multiplying the historical data by a factor of about 0.9.

Ecological longevity of Polaskia chende (Cactaceae) seeds in the soil seed bank, seedling emergence and survival.

PubMed

Ordoñez-Salanueva, C A; Orozco-Segovia, A; Canales-Martínez, M; Seal, C E; Pritchard, H W; Flores-Ortiz, C M

2017-11-01

Soil seed banks are essential elements of plant population dynamics, enabling species to maintain genetic variability, withstand periods of adversity and persist over time, including for cactus species. However knowledge of the soil seed bank in cacti is scanty. In this study, over a 5-year period we studied the seed bank dynamics, seedling emergence and nurse plant facilitation of Polaskia chende, an endemic columnar cactus of central Mexico. P. chende seeds were collected for a wild population in Puebla, Mexico. Freshly collected seeds were sown at 25 °C and 12-h photoperiod under white light, far-red light and darkness. The collected seeds were divided in two lots, the first was stored in the laboratory and the second was use to bury seeds in open areas and beneath a shrub canopy. Seeds were exhumed periodically over 5 years. At the same time seeds were sown in open areas and beneath shrub canopies; seedling emergence and survival were recorded over different periods of time for 5 years. The species forms long-term persistent soil seed banks. The timing of seedling emergence via germination in the field was regulated by interaction between light, temperature and soil moisture. Seeds entered secondary dormancy at specific times according to the expression of environmental factors, demonstrating irregular dormancy cycling. Seedling survival of P. chende was improved under Acacia constricta nurse plants. Finally, plant facilitation affected the soil seed bank dynamics as it promoted the formation of a soil seed bank, but not its persistence. © 2017 German Society for Plant Sciences and The Royal Botanical Society of the Netherlands.

Geology, mineralization, and hydrothermal alteration and relationships to acidic and metal-bearing surface waters in the Palmetto Gulch area, southwestern Colorado

USGS Publications Warehouse

Bove, Dana J.; Kurtz, Jeffrey P.; Wright, Winfield G.

2002-01-01

The Palmetto Gulch area is affected by low pH and metal-bearing drainage from abandoned mines, and perhaps, from natural weathering around vein zones. To investigate these anthropogenic and potential natural sources of acidity and metals, we mapped the geology, veins, and hydrothermally altered areas; conducted mine dump leachate studies; and collected reconnaissance water quality data. Several small abandoned mines are present in the Palmetto Gulch area that produced small amounts of relatively high-grade silver ore from fault-controlled polymetallic vein deposits. These veins are hosted in lavas, breccias, and related volcaniclastic sediments that ponded within the 28 Ma San Juan-Uncompahgre caldera complex. These rock units generally have conformable contacts and have shallow dips to the northwest. Lava flows of pyroxene andesite, which host the Roy-Pray mine, are massive near their base and typically grade upward into tightly jointed rock with 2-15 cm joint spacing. In general, most hydrothermally altered rock within the Palmetto Gulch area is restricted to envelopes surrounding the mineralized veins and faults. Composite zones of vein-related alteration vary from about 50 to 80 m wide along the high ridgelines and narrow to less than 10 to 15 m beneath an elevation of about 5,462 m. Where unaffected by surficial oxidation, these altered zones contain as much as 7 to 10 volume percent finely-disseminated pyrite. The majority of rocks in the area were affected by regional and vein-related propylitic alteration. These greenish-colored rocks have alteration products consisting of chlorite, illite, and calcite; and feldspars are typically weakly altered. Most of these rocks have detectable amounts of calcite, while as much as 11 percent by weight was detected in samples collected during this study. The Palmetto Gulch area is affected by low pH and metal-bearing drainage from abandoned mines, and perhaps, from natural weathering around vein zones. To investigate these anthropogenic and potential natural sources of acidity and metals, we mapped the geology, veins, and hydrothermally altered areas; conducted mine dump leachate studies; and collected reconnaissance water quality data. Several small abandoned mines are present in the Palmetto Gulch area that produced small amounts of relatively high-grade silver ore from fault-controlled polymetallic vein deposits. These veins are hosted in lavas, breccias, and related volcaniclastic sediments that ponded within the 28 Ma San Juan-Uncompahgre caldera complex. These rock units generally have conformable contacts and have shallow dips to the northwest. Lava flows of pyroxene andesite, which host the Roy-Pray mine, are massive near their base and typically grade upward into tightly jointed rock with 2-15 cm joint spacing. In general, most hydrothermally altered rock within the Palmetto Gulch area is restricted to envelopes surrounding the mineralized veins and faults. Composite zones of vein-related alteration vary from about 50 to 80 m wide along the high ridgelines and narrow to less than 10 to 15 m beneath an elevation of about 5,462 m. Where unaffected by surficial oxidation, these altered zones contain as much as 7 to 10 volume percent finely-disseminated pyrite. The majority of rocks in the area were affected by regional and vein-related propylitic alteration. These greenish-colored rocks have alteration products consisting of chlorite, illite, and calcite; and feldspars are typically weakly altered. Most of these rocks have detectable amounts of calcite, while as much as 11 percent by weight was detected in samples collected during this study.

A preliminary report on histological outcome of pulpotomy with endodontic biomaterials vs calcium hydroxide

PubMed Central

Peimani, Ali; Asgary, Saeed

2013-01-01

Objectives The purpose of the study was to evaluate human dental pulp response to pulpotomy with calcium hydroxide (CH), mineral trioxide aggregate (MTA), and calcium enriched mixture (CEM) cement. Materials and Methods A total of nine erupted third molars were randomly assigned to each pulpotomy group. The same clinician performed full pulpotomies and coronal restorations. The patients were followed clinically for six months; the teeth were then extracted and prepared for histological assessments. The samples were blindly assessed by an independent observer for pulp vitality, pulp inflammation, and calcified bridge formation. Results All patients were free of clinical signs/symptoms of pulpal/periradicular diseases during the follow up period. In CH group, one tooth had necrotic radicular pulp; other two teeth in this group had vital uninflamed pulps with complete dentinal bridge formation. In CEM cement and MTA groups all teeth had vital uninflamed radicular pulps. A complete dentinal bridge was formed beneath CEM cement and MTA in all roots. Odontoblast-like cells were present beneath CEM cement and MTA in all samples. Conclusions This study revealed that CEM cement and MTA were reliable endodontic biomaterials in full pulpotomy treatment. In contrast, the human dental pulp response to CH might be unpredictable. PMID:24303358

Upper mantle Q and thermal structure beneath Tanzania, East Africa from teleseismic P wave spectra

NASA Astrophysics Data System (ADS)

Venkataraman, Anupama; Nyblade, Andrew A.; Ritsema, Jeroen

2004-08-01

We measure P wave spectral amplitude ratios from deep-focus earthquakes recorded at broadband seismic stations of the Tanzania network to estimate regional variation of sublithospheric mantle attenuation beneath the Tanzania craton and the eastern branch of the East African Rift. One-dimensional profiles of QP adequately explain the systematic variation of P wave attenuation in the sublithospheric upper mantle: QP ~ 175 beneath the cratonic lithosphere, while it is ~ 80 beneath the rifted lithosphere. By combining the QP values and a model of P wave velocity perturbations, we estimate that the temperature beneath the rifted lithosphere (100-400 km depth) is 140-280 K higher than ambient mantle temperatures, consistent with the observation that the 410 km discontinuity in this region is depressed by 30-40 km.

The Quaternary calc-alkaline volcanism of the Patagonian Andes close to the Chile triple junction: geochemistry and petrogenesis of volcanic rocks from the Cay and Maca volcanoes (˜45°S, Chile)

NASA Astrophysics Data System (ADS)

D'Orazio, M.; Innocenti, F.; Manetti, P.; Tamponi, M.; Tonarini, S.; González-Ferrán, O.; Lahsen, A.; Omarini, R.

2003-08-01

Major- and trace-element, Sr-Nd isotopes, and mineral chemistry data were obtained for a collection of volcanic rock samples erupted by the Cay and Maca Quaternary volcanoes, Patagonian Andes (˜45°S, Chile). Cay and Maca are two large, adjacent stratovolcanoes that rise from the Chiloe block at the southern end of the southern volcanic zone (SVZ) of the Andes. Samples from the two volcanoes are typical medium-K, calc-alkaline rocks that form two roughly continuous, largely overlapping series from subalkaline basalt to dacite. The overall geochemistry of the samples studied is very similar to that observed for most volcanoes from the southern SVZ. The narrow range of Sr-Nd isotope compositions ( 87Sr/ 86Sr=0.70389-0.70431 and 143Nd/ 144Nd=0.51277-0.51284) and the major- and trace-element distributions indicate that the Cay and Maca magmas differentiated by crystal fractionation without significant contribution by crustal contamination. This is in accordance with the thin (<30 km), relatively young (Paleozoic or more recent) continental crust beneath the volcanoes. The nature of the subduction-derived materials involved in the genesis of the Cay and Maca magmas is investigated by means of the relative concentration of fluid mobile (e.g. Ba) and fluid immobile (e.g. Nb, Ta, Zr, Y) elements and other relevant trace-element ratios (e.g. Sr/Y). The results indicate that small amounts (<1 wt%) of both subducted sediments and slab-released fluids were added to the mantle sources of the Cay and Maca volcanoes and that, despite the very young age (<10 Ma) of the oceanic lithosphere subducted beneath the volcanoes, slab melts were not involved in the magma genesis. Notwithstanding the proximity of the Cay and Maca magma sources to the northern edge of the slab window generated by the subduction of the Chile ridge under the South American plate, we did not find any geochemical evidence for a contribution of a subslab asthenospheric mantle. However, this mantle has been used to explain the peculiar geochemical features (e.g. the mild alkalinity and relatively low ratios between large ion lithophile and high field strength elements) of the Hudson volcano, which is located even closer to the slab window than the Cay and Maca volcanoes are.

Selected natural attenuation monitoring data, Operable Unit 1, Naval Undersea Warfare Center, Division Keyport, Washington, June 2002

USGS Publications Warehouse

Dinicola, Richard S.

2004-01-01

Previous investigations indicated that natural attenuation and biodegradation of chlorinated volatile organic compounds (CVOCs) are substantial in shallow ground water beneath the 9-acre former landfill at Operable Unit 1 (OU 1), Naval Undersea Warfare Center (NUWC), Division Keyport, Washington. The U.S. Geological Survey (USGS) has continued to monitor ground-water geochemistry to assure that conditions remain favorable for contaminant biodegradation. This report presents the geochemical and selected CVOC data for ground water at OU 1, collected by the USGS during June 10-14, 2002, in support of long-term monitoring for natural attenuation. Overall, the geochemical data for June 2002 indicate that redox conditions in the upper-aquifer water remain favorable for reductive dechlorination of chlorinated VOCs because strongly reducing conditions persisted beneath much of the former landfill. Redox conditions in the intermediate aquifer downgradient of the landfill also remained favorable for reductive dechlorination, although the 2002 dissolved hydrogen (H2) concentration from well MW1-28 is questionable. Changes in redox conditions were observed at certain wells during 2002, but a longer monitoring period and more thorough interpretation are needed to ascertain if phytoremediation activities are affecting redox conditions and if biodegradation processes are changing over time. The Navy intends to complete a more thorough interpretation in preparation for the 5-year review of OU 1 scheduled for 2004. There were a few substantial differences between the 2002 concentrations and previously observed concentrations of volatile organic compounds. Total CVOC concentrations in 2002 samples decreased substantially in all piezometers sampled in the northern plantation, and the largest percentages of decrease were for the compounds trichloroethene (TCE) and cis-1,2-dichloroethene (cis-DCE). Changes in total CVOC concentrations in the southern plantation were less consistent. Historically high concentrations were observed in samples from three piezometers, with particularly substantial increases in TCE and cis-DCE concentrations, and historically low concentrations were observed in two piezometers, with particularly substantial decreases in TCE and cis-DCE concentrations. Similarly to the redox chemistry, a longer monitoring period and more thorough interpretation are needed to ascertain if phytoremediation activities are affecting CVOC concentrations and if biodegradation processes are changing over time. No changes in monitoring plans are proposed for June 2003, although the practice of deploying a data sonde downhole while purging the wells will be discontinued. Downhole monitoring added uncertainty to selected measured dissolved H2 concentrations because of the possibility that the sonde and cable created a bridge that resulted in non-equilibrium dissolved H2 concentrations at the wells.

Paleoseismology of the Nephi Segment of the Wasatch Fault Zone, Juab County, Utah - Preliminary Results From Two Large Exploratory Trenches at Willow Creek

USGS Publications Warehouse

Machette, Michael N.; Crone, Anthony J.; Personius, Stephen F.; Mahan, Shannon; Dart, Richard L.; Lidke, David J.; Olig, Susan S.

2007-01-01

In 2004, we identified a small parcel of U.S. Forest Service land at the mouth of Willow Creek (about 5 km west of Mona, Utah) that was suitable for trenching. At the Willow Creek site, which is near the middle of the southern strand of the Nephi segment, the WFZ has vertically displaced alluvial-fan deposits >6-7 m, forming large, steep, multiple-event scarps. In May 2005, we dug two 4- to 5-m-deep backhoe trenches at the Willow Creek site, identified three colluvial wedges in each trench, and collected samples of charcoal and A-horizon organic material for AMS (acceleration mass spectrometry) radiocarbon dating, and sampled fine-grained eolian and colluvial sediment for luminescence dating. The trenches yielded a stratigraphic assemblage composed of moderately coarse-grained fluvial and debris-flow deposits and discrete colluvial wedges associated with three faulting events (P1, P2, and P3). About one-half of the net vertical displacement is accommodated by monoclinal tilting of fan deposits on the hanging-wall block, possibly related to massive ductile landslide deposits that are present beneath the Willow Creek fan. The timing of the three surface-faulting events is bracketed by radiocarbon dates and results in a much different fault chronology and higher slip rates than previously considered for this segment of the Wasatch fault zone.

Hyperfine and radiological characterization of soils of the province of Buenos Aires, Argentina

NASA Astrophysics Data System (ADS)

Montes, M. L.; Taylor, M. A.; Mercader, R. C.; Sives, F. R.; Desimoni, J.

2010-03-01

The depth profile concentration of both natural and anthropogenic gamma-ray-emitter nuclides were determined in soil samples collected in an area located at 34° 54.452' S, 58° 8.365' W, down to 50 cm in depth, using an hyper-pure Ge spectrometer. The soil samples were also characterized by means of Mössbauer spectrometry and X-ray diffraction. The activities of 238U and 232Th natural chains remain constant in depth at 41 Bq/kg and 46 Bq/kg, respectively, while the 40K activity increases from 531 Bq/kg to 618 Bq/kg between 2.5 cm y 25.5 cm of depth. The only anthropogenic detected nuclide is 137Cs, whose activity changes form 1.4 Bq/kg to values lower than the detection limit (LD) for depths below 25 cm, exhibiting a maximum at 10 cm beneath the surface. The Mössbauer spectra show two magnetic sextets associated with α-Fe2O3 and Fe3O4, as well as two Fe+3 Fe+2 doublets, probably originated in octahedral and tetrahedral sites of paramagnetic phases. The Fe3+ paramagnetic signal relative fraction increases up to 82% at the expense of the α-Fe2O3 one when de depth increases. No correlation between Fe3O4 and the 137Cs was identificated.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Flach, G. P.; Whiteside, T. S.

The E-Area Vadose Zone Monitoring System (VZMS) includes lysimeter sampling points at many locations alongside and angling beneath the Engineered Trench #1 (ET1) disposal unit footprint. The sampling points for ET1 were selected for this study because collectively they showed consistently higher tritium (H-3) concentrations than lysimeters associated with other trench units. The VZMS tritium dataset for ET1 from 2001 through 2015 comprises concentrations at or near background levels at approximately half of locations through time, concentrations up to about 600 pCi/mL at a few locations, and concentrations at two locations that have exceeded 1000 pCi/mL. The highest three valuesmore » through 2015 were 6472 pCi/mL in 2014 and 4533 pCi/mL in 2013 at location VL-17, and 3152 pCi/mL in 2007 at location VL-15. As a point of reference, the drinking water standard for tritium and a DOE Order 435.1 performance objective in the saturated zone at the distant 100-meter facility perimeter is 20 pCi/mL. The purpose of this study is to assess whether these elevated concentrations are indicative of a general trend that could challenge 2008 E-Area Performance Assessment (PA) conclusions, or are isolated perturbations that when considered in the context of an entire disposal unit would support PA conclusions.« less

Mercury in fruiting bodies of dark honey fungus (Armillaria solidipes) and beneath substratum soils collected from spatially distant areas.

PubMed

Falandysz, Jerzy; Mazur, Aneta; Kojta, Anna K; Jarzyńska, Grażyna; Drewnowska, Małgorzata; Dryżałowska, Anna; Nnorom, Innocent C

2013-03-15

This paper reports data on bioconcentration potential and baseline mercury concentrations of fruiting bodies of dark honey fungus (Armillaria solidipes) Peck and soil substrate layer (0-10 cm) from 12 spatially distant sites across Poland. Mercury content of caps, stipes and soil samples were determined using validated analytical procedure including cold-vapor atomic absorption spectroscopy after thermal decomposition of the sample matrix and further amalgamation and desorption of mercury from gold wool. Mean mercury concentrations ranged from 20 ± 8 to 300 ± 70 ng g(-1) dry weight (dw) in caps, from 20 ± 6 to 160 ± 40 ng g(-1) dw in stipes, and in underlying soil were from 20 ± 2 to 100 ± 130 ng g(-1) dw. The results showed that stipes mercury concentrations were 1.1- to 1.7-fold lower than those of caps. All caps and the majority of stipes were characterized by bioconcentration factor values > 1, indicating that dark honey fungus can be characterized as a moderate mercury accumulator. Occasional or relatively frequent eating of meals including caps of dark honey fungus is considered safe in view of the low total mercury content, and the mercury intake rates are below the current reference dose and provisionally tolerable weekly intake limits for this hazardous metal. © 2012 Society of Chemical Industry.

Nd and Sr isotopic variations in acidic rocks from Japan: significance of upper-mantle heterogeneity

NASA Astrophysics Data System (ADS)

Terakado, Yasutaka; Nakamura, Noboru

1984-10-01

Initial Nd and Sr isotopic ratios have been measured for Cretaceous acidic and related intermediate rocks (24 volcanic and two plutonic rocks) from the Inner Zone of Southwest Japan (IZSWJ) to investigate the genesis of acidic magmas. The initial Nd and Sr isotopic ratios for these rocks show three interesting features: (1) ɛ Nd values for acidic rocks (+2 to -9) are negatively correlated with ɛ Sr values (+10 to +90) together with those for intermediate rocks ( ɛ Nd=+3 to -8; ɛ Sr=0 to +65). (2) The ɛ Nd values for silica rich rocks (>60% SiO2) correlate with the longitude of the sample locality, decreasing from west to east in a stepwise fashion: Four areas characterized by uniform ɛ Nd values are discriminated. (3) Low silica rocks (<60% SiO2) in a certain area have distinctly different ɛ Nd values from those of the high silica rocks in the same area. These results as well as those deduced from the additional samples collected, for comparison, from other provinces in Japan suggest that the acidic rocks can be formed neither by fractional crystallization processes from more basic magmas nor by crustal assimilation processes. The isotopic variations of the acidic rocks may reflect regional isotopic heterogeneity in the lower crust, and this heterogeneity may ultimately be attributed to the regional heterogeneity of the uppermost-mantle beneath the Japanese Islands.

Distribution of Magma and Hydrothermal Fluids Beneath the Laguna del Maule Volcanic Field, Central Chile Using Magnetotelluric Data

NASA Astrophysics Data System (ADS)

Unsworth, M. J.; Cordell, D. R.; Diaz, D.; Reyes, V.

2016-12-01

Geodetic data has shown that the surface around the Laguna del Maule volcanic field in central Chile has been moving upwards at rates in excess of 19 cm/yr since 2007 over a 200 km2 area. It has been hypothesized that this ground deformation is due to the inflation of a magma body beneath the lake. InSAR deformation modeling and gravity inversion suggest that the depth to the magma body is between 3 km b.s.l. and 0 km (at sea level). This magma body is a likely source for the large number of rhyolitic eruptions at this location over the last 25 ka. A dense broadband magnetotelluric (MT) array was collected from 2009 to 2015 and inverted using the ModEM inversion algorithm to produce a three-dimensional electrical resistivity model. The presence of a large surface conductor (<0.5 Ωm; 2.3 km a.s.l.) spatially coincident with the lake bed has the potential to attenuate signal and decrease resolution beneath the area of inflation. Additional broadband MT data were collected in 2016 and this new data suggest there is a mid-depth, weakly conductive feature (5 Ωm; 1 km b.s.l.) coincident with the area of maximum inflation which is resolvable despite the low-resistivity surface layer. There are many conductive features which lie on the perimeter of the zone of inflation including a large low-resistivity zone (<5 Ωm) at 5 km depth (3 km b.s.l.) north-west of the lake and a large low-resistivity zone (<10 Ωm) at 5 km depth (3 km b.s.l) north of the lake. The complex, three-dimensional model structure is supported by phase tensor analysis showing poorly-defined strike and high beta skew values (>3) at periods >2 s. The conductive features identified could be interpreted as either hydrothermal systems or magma and further analysis will contribute to better understanding this dynamic system.

Microbial Community Structure of Subglacial Lake Whillans, West Antarctica

PubMed Central

Achberger, Amanda M.; Christner, Brent C.; Michaud, Alexander B.; Priscu, John C.; Skidmore, Mark L.; Vick-Majors, Trista J.; Adkins, W.

2016-01-01

Subglacial Lake Whillans (SLW) is located beneath ∼800 m of ice on the Whillans Ice Stream in West Antarctica and was sampled in January of 2013, providing the first opportunity to directly examine water and sediments from an Antarctic subglacial lake. To minimize the introduction of surface contaminants to SLW during its exploration, an access borehole was created using a microbiologically clean hot water drill designed to reduce the number and viability of microorganisms in the drilling water. Analysis of 16S rRNA genes (rDNA) amplified from samples of the drilling and borehole water allowed an evaluation of the efficacy of this approach and enabled a confident assessment of the SLW ecosystem inhabitants. Based on an analysis of 16S rDNA and rRNA (i.e., reverse-transcribed rRNA molecules) data, the SLW community was found to be bacterially dominated and compositionally distinct from the assemblages identified in the drill system. The abundance of bacteria (e.g., Candidatus Nitrotoga, Sideroxydans, Thiobacillus, and Albidiferax) and archaea (Candidatus Nitrosoarchaeum) related to chemolithoautotrophs was consistent with the oxidation of reduced iron, sulfur, and nitrogen compounds having important roles as pathways for primary production in this permanently dark ecosystem. Further, the prevalence of Methylobacter in surficial lake sediments combined with the detection of methanogenic taxa in the deepest sediment horizons analyzed (34–36 cm) supported the hypothesis that methane cycling occurs beneath the West Antarctic Ice Sheet. Large ratios of rRNA to rDNA were observed for several operational taxonomic units abundant in the water column and sediments (e.g., Albidiferax, Methylobacter, Candidatus Nitrotoga, Sideroxydans, and Smithella), suggesting a potentially active role for these taxa in the SLW ecosystem. Our findings are consistent with chemosynthetic microorganisms serving as the ecological foundation in this dark subsurface environment, providing new organic matter that sustains a microbial ecosystem beneath the West Antarctic Ice Sheet. PMID:27713727

Helium as a tracer for fluids released from Juan de Fuca lithosphere beneath the Cascadia forearc

USGS Publications Warehouse

McCrory, Patricia A.; Constantz, James E.; Hunt, Andrew G.; Blair, James Luke

2016-01-01

The ratio between helium isotopes (3He/4He) provides an excellent geochemical tracer for investigating the sources of fluids sampled at the Earth's surface. 3He/4He values observed in 25 mineral springs and wells above the Cascadia forearc document a significant component of mantle-derived helium above Juan de Fuca lithosphere, as well as variability in 3He enrichment across the forearc. Sample sites arcward of the forearc mantle corner (FMC) generally yield significantly higher ratios (1.2-4.0 RA) than those seaward of the corner (0.03-0.7 RA). The highest ratios in the Cascadia forearc coincide with slab depths (40-45 km) where metamorphic dehydration of young oceanic lithosphere is expected to release significant fluid and where tectonic tremor occurs, whereas little fluid is expected to be released from the slab depths (25-30 km) beneath sites seaward of the corner.Tremor (considered a marker for high fluid pressure) and high RA values in the forearc are spatially correlated. The Cascadia tremor band is centered on its FMC, and we tentatively postulate that hydrated forearc mantle beneath Cascadia deflects a significant portion of slab-derived fluids updip along the subduction interface, to vent in the vicinity of its corner. Furthermore, high RA values within the tremor band just arcward of the FMC, suggest that the innermost mantle wedge is relatively permeable.Conceptual models require: (1) a deep fluid source as a medium to transport primordial 3He; (2) conduits through the lithosphere which serve to speed fluid ascent to the surface before significant dilution from radiogenic 4He can occur; and (3) near lithostatic fluid pressure to keep conduits open. Our spatial correlation between high RA values and tectonic tremor provides independent evidence that tremor is associated with deep fluids, and it further suggests that high pore pressures associated with tremor may serve to keep fractures open for 3He migration through ductile upper mantle and lower crust.

Seismic imaging beneath an InSAR anomaly in eastern Washington State: Shallow faulting associated with an earthquake swarm in a low-hazard area

USGS Publications Warehouse

Stephenson, William J.; Odum, Jackson K.; Wicks, Chuck; Pratt, Thomas L.; Blakely, Richard J.

2016-01-01

In 2001, a rare swarm of small, shallow earthquakes beneath the city of Spokane, Washington, caused ground shaking as well as audible booms over a five‐month period. Subsequent Interferometric Synthetic Aperture Radar (InSAR) data analysis revealed an area of surface uplift in the vicinity of the earthquake swarm. To investigate the potential faults that may have caused both the earthquakes and the topographic uplift, we collected ∼3  km of high‐resolution seismic‐reflection profiles to image the upper‐source region of the swarm. The two profiles reveal a complex deformational pattern within Quaternary alluvial, fluvial, and flood deposits, underlain by Tertiary basalts and basin sediments. At least 100 m of arching on a basalt surface in the upper 500 m is interpreted from both the seismic profiles and magnetic modeling. Two west‐dipping faults deform Quaternary sediments and project to the surface near the location of the Spokane fault defined from modeling of the InSAR data.

Along-arc variation in water distribution in the upper mantle beneath Kyushu, Japan, as derived from receiver function analyses

NASA Astrophysics Data System (ADS)

Abe, Y.; Ohkura, T.; Hirahara, K.; Shibutani, T.

2013-12-01

The Kyushu district, Japan, under which the Philippine Sea (PHS) plate is subducting in a WNW direction, has several active volcanoes. On the volcanic front in Kyushu, a 110 km long gap in volcanism exists in the central part of Kyushu and volcanic rocks with various degrees of contamination by slab-derived fluid are distributed. To reveal the causes of the gap in volcanism and the chemical properties of volcanic rocks and to understand the process of magma genesis and water transportation, we should reveal along-arc variation in water distribution beneath Kyushu. We investigated the seismic velocity discontinuities in the upper mantle beneath Kyushu, with seismic waveform data from 65 stations of Hi-net, which are established by National Research Institute for Earth Science and Disaster Prevention, and 55 stations of the J-array, which are established by Japan Meteorological Agency, Kyushu University, Kagoshima University and Kyoto University. We used receiver function analyses developed especially for discontinuities with high dipping angles (Abe et al., 2011, GJI). We obtained the geometry and velocity contrasts of the continental Moho, the oceanic Moho, and the upper boundary of the PHS slab. From the geometry of these discontinuities and contrast in S wave velocities, we interpreted that the oceanic crust of the PHS slab has a low S wave velocity and is hydrated to a depth of 70 km beneath south Kyushu, to a depth of 80-90 km beneath central Kyushu, and to a depth of no more than 50 km beneath north Kyushu. We also interpreted that the fore-arc mantle beneath central Kyushu has a low velocity region (Vs < 3.2 km/s) that can contain hydrated materials and free aqueous fluid. Such a low velocity fore-arc mantle does not exist beneath north and south Kyushu. Beneath north Kyushu, the oceanic crust does not appear to convey much water in the mantle wedge. Beneath south Kyushu, water dehydrated from the slab could move to the back-arc side and cause arc volcanism, while it could move to the fore-arc side and cause a gap in volcanism and hydration of the fore-arc mantle materials.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adams, Aubreya N.; Wiens, Douglas A.; Nyblade, Andrew A.

The Cameroon Volcanic Line (CVL) is a 1800 km long volcanic chain, extending SW-NE from the Gulf of Guinea into Central Africa, that lacks the typical age progression exhibited by hot spot-related volcanic tracks. Our study investigates the upper mantle seismic structure beneath the CVL and surrounding regions to constrain the origin of volcanic lines that are poorly described by the classic plume model. Rayleigh wave phase velocities are measured at periods from 20 to 182 s following the two-plane wave methodology, using data from the Cameroon Seismic Experiment, which consists of 32 broadband stations deployed between 2005 and 2007.more » These phase velocities are then inverted to build a model of shear wave velocity structure in the upper mantle beneath the CVL. Our results show that phase velocities beneath the CVL are reduced at all periods, with average velocities beneath the CVL deviating more than –2% from the regional average and +4% beneath the Congo Craton. This distinction is observed for all periods but is less pronounced for the longest periods measured. Inversion for shear wave velocity structure indicates a tabular low velocity anomaly directly beneath the CVL at depths of 50 to at least 200 km and a sharp vertical boundary with faster velocities beneath the Congo Craton. Finally, these observations demonstrate widespread infiltration or erosion of the continental lithosphere beneath the CVL, most likely caused by mantle upwelling associated with edge-flow convection driven by the Congo Craton or by lithospheric instabilities that develop due to the nearby edge of the African continent.« less

A new view into the Cascadia subduction zone and volcanic arc: Implications for earthquake hazards along the Washington margin

USGS Publications Warehouse

Parsons, T.; Trehu, A.M.; Luetgert, J.H.; Miller, K.; Kilbride, F.; Wells, R.E.; Fisher, M.A.; Flueh, E.; ten Brink, Uri S.; Christensen, N.I.

1998-01-01

In light of suggestions that the Cascadia subduction margin may pose a significant seismic hazard for the highly populated Pacific Northwest region of the United States, the U.S. Geological Survey (USGS), the Research Center for Marine Geosciences (GEOMAR), and university collaborators collected and interpreted a 530-km-long wide-angle onshore-offshore seismic transect across the subduction zone and volcanic arc to study the major structures that contribute to seismogenic deformation. We observed (1) an increase in the dip of the Juan de Fuca slab from 2°–7° to 12° where it encounters a 20-km-thick block of the Siletz terrane or other accreted oceanic crust, (2) a distinct transition from Siletz crust into Cascade arc crust that coincides with the Mount St. Helens seismic zone, supporting the idea that the mafic Siletz block focuses seismic deformation at its edges, and (3) a crustal root (35–45 km deep) beneath the Cascade Range, with thinner crust (30–35 km) east of the volcanic arc beneath the Columbia Plateau flood basalt province. From the measured crustal structure and subduction geometry, we identify two zones that may concentrate future seismic activity: (1) a broad (because of the shallow dip), possibly locked part of the interplate contact that extends from ∼25 km depth beneath the coastline to perhaps as far west as the deformation front ∼120 km offshore and (2) a crustal zone at the eastern boundary between the Siletz terrane and the Cascade Range.

Differential effects of lichens, mosses and grasses on respiration and nitrogen mineralization in soils of the New Jersey Pinelands.

PubMed

Sedia, Ekaterina G; Ehrenfeld, Joan G

2005-06-01

In the New Jersey Pinelands, severely disturbed areas often do not undergo a rapid succession to forest; rather, a patchy cover of lichens, mosses and grasses persists for decades. We hypothesized that these plant covers affect soil microbial processes in different ways, and that these effects may alter the successional dynamics of the patches. We predicted that the moss and grass covers stimulate soil microbial activity, whereas lichens inhibit it, which may in turn inhibit succession. We collected soil cores from beneath each type of cover plus bare soil within two types of highly disturbed areas--sites subjected to hot wildfires, and areas mined for sand. Organic matter (OM) content, soil respiration and potential N mineralization were measured in the cores. Soils under mosses were similar to those under grasses; they accumulated more OM and produced more mineral N, predominantly in the form of ammonium, than either the bare soils or the soils beneath lichens. Mineralization under lichens, like that of the bare soils but unlike the soils beneath mosses or grasses, was dominated by net nitrification. These patterns were reproduced in experimentally transplanted moss and lichen mats. Mosses appear to create high-nutrient microsites via high rates of OM accumulation and production of ammonium, whereas lichens maintain low-nutrient patches similar to bare soil via low OM accumulation rates and production of mineral N predominantly in the mobile nitrate form. These differences in soil properties may explain the lack of vascular plant invasion in lichen mats, in contrast to the moss-dominated areas.

Fluctuating pressures measured beneath a high-temperature, turbulent boundary layer on a flat plate at Mach number of 5

NASA Technical Reports Server (NTRS)

Parrott, Tony L.; Jones, Michael G.; Albertson, Cindy W.

1989-01-01

Fluctuating pressures were measured beneath a Mach 5, turbulent boundary layer on a flat plate with an array of piezoresistive sensors. The data were obtained with a digital signal acquisition system during a test run of 4 seconds. Data sampling rate was such that frequency analysis up to 62.5 kHz could be performed. To assess in situ frequency response of the sensors, a specially designed waveguide calibration system was employed to measure transfer functions of all sensors and related instrumentation. Pressure time histories were approximated well by a Gaussian prohibiting distribution. Pressure spectra were very repeatable over the array span of 76 mm. Total rms pressures ranged from 0.0017 to 0.0046 of the freestream dynamic pressure. Streamwise, space-time correlations exhibited expected decaying behavior of a turbulence generated pressure field. Average convection speed was 0.87 of freestream velocity. The trendless behavior with sensor separation indicated possible systematic errors.

Evidence for Extending Anomalous Miocene Volcanism at the Edge of the East Antarctic Craton

NASA Astrophysics Data System (ADS)

Licht, K. J.; Groth, T.; Townsend, J. P.; Hennessy, A. J.; Hemming, S. R.; Flood, T. P.; Studinger, M.

2018-04-01

Using field observations followed by petrological, geochemical, geochronological, and geophysical data, we infer the presence of a previously unknown Miocene subglacial volcanic center 230 km from the South Pole. Evidence of volcanism is from boulders of olivine-bearing amygdaloidal/vesicular basalt and hyaloclastite deposited in a moraine in the southern Transantarctic Mountains. 40Ar/39Ar ages from five specimens plus U-Pb ages of detrital zircon from glacial till indicate igneous activity 25-17 Ma. The likely source of the volcanism is a circular -735 nT magnetic anomaly 60 km upflow from the sampling site. Subaqueous textures of the volcanics indicate eruption beneath ice or into water at the margin of an ice mass during the early Miocene. These rocks record the southernmost Cenozoic volcanism in Antarctica and expand the known extent of the oldest lavas associated with West Antarctic Rift system. They may be an expression of lithospheric foundering beneath the southern Transantarctic Mountains.

Distribution of major herbicides in ground water of the United States

USGS Publications Warehouse

Barbash, Jack E.; Thelin, Gail P.; Kolpin, Dana W.; Gilliom, Robert J.

1999-01-01

Frequencies of detection at or above 0.01 microgram per liter in shallow ground water beneath agricultural areas during the NAWQA study were significantly correlated with agricultural use in those areas for atrazine, cyanazine, alachlor, and metolachlor (P<0.05; Spearman rank correlations), but not for simazine (P>0.05). In urban areas, overall frequencies of detection of these five herbicides in shallow ground water were positively correlated with their total nonagricultural use nationwide (P=0.026; simple linear correlation). Multivariate statistical analysis indicated that frequencies of detection in shallow ground water beneath agricultural areas were positively correlated with half-lives for transformation in aerobic soil and agricultural use of the compounds (P≤0.0001 for both parameters). Although frequencies of detection were not significantly correlated with their subsurface mobility (Koc; P=0.19) or the median well depths of the sampled networks (P=0.72), the range of Koc values among the five herbicides and the range of well depths were limited.

Core drilling provides information about Santa Fe Group aquifer system beneath Albuquerque's West Mesa

USGS Publications Warehouse

Allen, B.D.; Connell, S.D.; Hawley, J.W.; Stone, B.D.

1998-01-01

Core samples from the upper ???1500 ft of the Santa Fe Group in the Albuquerque West Mesa area provide a first-hand look at the sediments and at subsurface stratigraphic relationships in this important part of the basin-fill aquifer system. Two major hydrostratigraphic subunits consisting of a lower coarse-grained, sandy interval and an overlying fine-grained, interbedded silty sand and clay interval lie beneath the water table at the 98th St core hole. Borehole electrical conductivity measurements reproduce major textural changes observed in the recovered cores and support subsurface correlations of hydrostratigraphic units in the Santa Fe Group aquifer system based on geophysical logs. Comparison of electrical logs from the core hole and from nearby city wells reveals laterally consistent lithostratigraphic patterns over much of the metropolitan area west of the Rio Grande that may be used to delineate structural and related stratigraphic features that have a direct bearing on the availability of ground water.

Cosmic Radiation Exposure of Biological Test Systems During the EXPOSE-E Mission

PubMed Central

Hajek, Michael; Bilski, Pawel; Körner, Christine; Vanhavere, Filip; Reitz, Günther

2012-01-01

Abstract In the frame of the EXPOSE-E mission on the Columbus external payload facility EuTEF on board the International Space Station, passive thermoluminescence dosimeters were applied to measure the radiation exposure of biological samples. The detectors were located either as stacks next to biological specimens to determine the depth dose distribution or beneath the sample carriers to determine the dose levels for maximum shielding. The maximum mission dose measured in the upper layer of the depth dose part of the experiment amounted to 238±10 mGy, which relates to an average dose rate of 408±16 μGy/d. In these stacks of about 8 mm height, the dose decreased by 5–12% with depth. The maximum dose measured beneath the sample carriers was 215±16 mGy, which amounts to an average dose rate of 368±27 μGy/d. These values are close to those assessed for the interior of the Columbus module and demonstrate the high shielding of the biological experiments within the EXPOSE-E facility. Besides the shielding by the EXPOSE-E hardware itself, additional shielding was experienced by the external structures adjacent to EXPOSE-E, such as EuTEF and Columbus. This led to a dose gradient over the entire exposure area, from 215±16 mGy for the lowest to 121±6 mGy for maximum shielding. Hence, the doses perceived by the biological samples inside EXPOSE-E varied by 70% (from lowest to highest dose). As a consequence of the high shielding, the biological samples were predominantly exposed to galactic cosmic heavy ions, while electrons and a significant fraction of protons of the radiation belts and solar wind did not reach the samples. Key Words: Space radiation—Dosimetry—Passive radiation detectors—Thermoluminescence—EXPOSE-E. Astrobiology 12, 387–392. PMID:22680685

Focused ground-water recharge in the Amargosa Desert basin: Chapter E in Ground-water recharge in the arid and semiarid southwestern United States (Professional Paper 1703)

USGS Publications Warehouse

Stonestrom, David A.; Prudic, David E.; Walvoord, Michelle Ann; Abraham, Jared D.; Stewart-Deaker, Amy E.; Glancy, Patrick A.; Constantz, Jim; Laczniak, Randell J.; Andraski, Brian J.; Stonestrom, David A.; Constantz, Jim; Ferré, Ty P.A.; Leake, Stanley A.

2007-01-01

The Amargosa River is an approximately 300-kilometer long regional drainage connecting the northern highlands on the Nevada Test Site in Nye County, Nev., to the floor of Death Valley in Inyo County, Calif. Streamflow analysis indicates that the Amargosa Desert portion of the river is dry more than 98 percent of the time. Infiltration losses during ephemeral flows of the Amargosa River and Fortymile Wash provide the main sources of ground-water recharge on the desert-basin floor. The primary use of ground water is for irrigated agriculture. The current study examined ground-water recharge from ephemeral flows in the Amargosa River by using streamflow data and environmental tracers. The USGS streamflow-gaging station at Beatty, Nev., provided high-frequency data on base flow and storm runoff entering the basin during water years 1998–2001. Discharge into the basin during the four-year period totaled 3.03 million cubic meters, three quarters of which was base flow. Streambed temperature anomalies indicated the distribution of ephemeral flows and infiltration losses within the basin. Major storms that produced regional flow during the four-year period occurred in February 1998, during a strong El Niño that more than doubled annual precipitation, and in July 1999. The study also quantified recharge beneath undisturbed native vegetation and irrigation return flow beneath irrigated fields. Vertical profiles of water potential and environmental tracers in the unsaturated zone provided estimates of recharge beneath the river channel (0.04–0.09 meter per year) and irrigated fields (0.1–0.5 meter per year). Chloride mass-balance estimates indicate that 12–15 percent of channel infiltration becomes ground-water recharge, together with 9–22 percent of infiltrated irrigation. Profiles of potential and chloride beneath the dominant desert-shrub vegetation suggest that ground-water recharge has been negligible throughout most of the basin since at least the early Holocene. Surface-based electrical-resistivity imaging provided areal extension of borehole information from sampled profiles. These images indicate narrowly focused recharge beneath the Amargosa River channel, flanked by large tracts of recharge-free basin floor.

Evidence for liquefaction identified in peeled slices of Holocene deposits along the Lower Columbia River, Washington

USGS Publications Warehouse

Takada, K.; Atwater, B.F.

2004-01-01

Peels made from 10 geoslices beneath a riverbank at Washington's Hunting Island, 45 km inland from the Pacific coast, aid in identifying sand that liquefied during prehistoric earthquakes of estimated magnitude 8-9 at the Cascadia subduction zone. Each slice was obtained by driving sheetpile and a shutter plate to depths of 6-8 m. The resulting sample, as long as 8 m, had a trapezoidal cross section 42-55 cm by 8 cm. The slicing created few artifacts other than bending and smearing at slice edges. Each slice is dominated by well-stratified sand and mud deposited by the tidal Columbia River. Nearly 90% of the sand is distinctly laminated. The sand contains mud beds as thick as 0.5 m and at least 20 m long, and it is capped by a mud bed that contains a buried soil that marks the 1700 Cascadia earthquake of estimated magnitude 9. Every slice intersected sills and dikes of fluidized sand, and many slices show folds and faults as well. Sills, which outnumber dikes, mostly follow and locally invade the undersides of mud beds. The mud beds probably impeded diffuse upward flow of water expelled from liquefied sand. Trapped beneath mud beds, this water flowed laterally, destroyed bedding by entraining (fluidizing) sand, and locally scoured the overlying mud. Horizontal zones of folded sand extend at least 10 or 20 m, and some contain low-angle faults. Many of the folds probably formed while sand was weakened by liquefaction. The low-angle faults may mark the soles of river-bottom slumps or lateral spreads. As many as four great Cascadia earthquakes in the past 2000 yr contributed to the intrusions, folds, and faults. This subsurface evidence for fluid escape and deformation casts doubt on maximum accelerations that were previously inferred from local absence of liquefaction features at the ground surface along the Columbia River. The geosliced evidence for liquefaction abounds not only beneath banks riddled with dikes but also beneath banks in which dikes are absent. Such dike-free banks of the Columbia River, if interpreted without study of postdepositional structures in deposits beneath them, provide insufficient basis for setting upper bounds on the strength of shaking from great Cascadia earthquakes. Online material: Data from outcrop surveys, vibracores, and penetrometer tests; tabular summary of depositional and postdepositional features in geoslices.

Gas hydrate exploration of Porangahau Ridge, East Coast, North Island, New Zealand

NASA Astrophysics Data System (ADS)

Pecher, I. A.; Henrys, S. A.; Crutchley, G.; Toulmin, S.; Gorman, A. R.; Wood, W. T.; Kukowski, N.; Greinert, J.; Faure, K.; Coffin, R. B.

2007-12-01

During June and July 2006 the R/V Tangaroa collected high-resolution seismic profiles, EM 300 swath bathymetry, 3.5 sub-bottom, as well as water column echosounder data across Porangahau Ridge east of the North Island. Piston cores were recovered for pore water chemistry, microbiology, and paleoceanographic analyses. We also acquired heatflow data, CTDs, and seawater samples for water-column chemistry. The seismic data show amplitude anomalies beneath the ridge. The anomalies develop along a prominent N-S fault-propagation anticline. We analyzed reflection coefficients and conclude that the anomalies are most likely caused by free gas within the regional gas hydrate stability field as defined by the depth of bottom simulating reflections. We suggest that local warming associated with fluid expulsion through faults keeps the temperature at the anomalies outside of the gas hydrate stability field. Based on the seismic amplitudes, we predict at least ~7% of the pore space to be saturated with gas if gas is evenly distributed. Gas saturation is predicted to be almost 70% for "patchy'' gas distribution. For the pressure-temperature conditions beneath the ridge, gas at a saturation of 7% would form gas hydrate at a saturation of ~10% of pore space. Should the localized heat flow anomaly weaken, e.g., because of sealing of the faults, the ridge could become an area with significant hydrate deposits. We speculate that the Porangahau Ridge constitutes a gas hydrate "sweet spot" in the process of formation. Pore water chemistry shows a shoaling of the base of the sulfate reduction zone across this feature, indicative of elevated methane flux through the hydrate stability field. There is a distinct thermal anomaly across the Porangahau Ridge, albeit with a complex signature. On the other hand, there are no indications of methane expulsion into the water column, neither in the echosounder records nor in the water chemistry profiles from CTDs.

Sedimentary framework of Penobscot Bay, Maine

USGS Publications Warehouse

Knebel, Harley J.; Scanlon, Kathryn M.

1985-01-01

Analyses of seismic-reflection profiles, along with previously collected sediment samples and geologic information from surrounding coastal areas, outline the characteristics, distribution, and history of the strata that accumulated within Penobscot Bay, Maine, during the complex period of glaciation, crustal movement, and sea-level change since late Wisconsinan time. Sediments that overlie the rugged, glacially eroded surface of Paleozoic bedrock range in thickness from near zero to more than 50 m and consist of four distinct units.Massive to partly stratified, coarse-grained drift forms thin (< 15 m) isolated patches along the walls and floors of bedrock troughs and constitutes a thick (up to 30 m), hummocky end moraine in the central part of the bay. The drift was deposited by the last ice sheet between 12,700 and 13,500 years ago during deglaciation and coastal submergence (due to crustal depression).Well-stratified, fine-grained glaciomarine deposits are concentrated in bedrock depressions beneath the main passages of the bay. During the period of ice retreat and marine submergence, these sediments settled to the sea floor, draped the irregular underlying surface of bedrock or drift, and accumulated without disturbance by physical or biologic processes.Heterogeneous fluvial deposits fill ancestral channels of the Penobscot River beneath the head of the bay. The channels were incised during a −40 m postglacial low stand of sea level (due to crustal rebound) and later were filled as base level was increased during Holocene time.Muddy marine sediments, which are homogeneous to weakly stratified and rich in organic matter, blanket older deposits within bathymetric depressions in the middle and lower reaches of the bay and cover a pronounced, gently dipping, erosional unconformity in the upper reach. These sediments were deposited during the Holocene transgression as sea level approached its present position and the bay became deeper.Late Wisconsinan and Holocene sedimentation in Penobscot Bay has smoothed the sea floor, but it has not completely obscured the ice-sculptured bedrock topography.

Investigating the subsurface connection beneath Cerro Negro volcano and the El Hoyo Complex, Nicaragua

NASA Astrophysics Data System (ADS)

Venugopal, Swetha; Moune, Séverine; Williams-Jones, Glyn

2016-10-01

Cerro Negro, the youngest volcano along the Central American Volcanic Belt (CAVB), is a polygenetic cinder cone with relatively frequent basaltic eruptions. The neighbouring El Hoyo complex, of which Las Pilas is the dominant edifice, is a much larger and older complex with milder and less frequent eruptions. Previous studies have suggested a deep link beneath these two closely spaced volcanoes (McKnight, 1995; MacQueen, 2013). Melt inclusions were collected from various tephra samples in order to determine whether a connection exists and to delineate the features of this link. Major, volatile, and trace elemental compositions reveal a distinct geochemical continuum with Cerro Negro defining the primitive endmember and El Hoyo representing the evolved endmember. Magmatic conditions at the time of melt inclusion entrapment were estimated with major and volatile contents: 2.4 kbar and 1170 °C for Cerro Negro melts and 1.3 kbar and 1130 °C for El Hoyo melts with an overall oxygen fugacity at the NNO buffer. Trace element contents are distinct and suggest Cerro Negro magmas fractionally crystallise while El Hoyo magmas are a mix between primitive Cerro Negro melts and residual and evolved El Hoyo magma. Modelling of end member compositions with alphaMELTS confirms the unique nature of El Hoyo magmas as resulting from incremental mixing between Cerro Negro and residual evolved magma at 4 km depth. Combining all available literature data, this study presents a model of the interconnected subsurface plumbing system. This model considers the modern day analogue of the Lemptégy cinder cones in Massif Central, France and incorporates structurally controlled dykes. The main implications of this study are the classification of Cerro Negro as the newest conduit within the El Hoyo Complex as well as the potential re-activation of the El Hoyo edifice.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hernández-Rosales, E.; Cedeño, E.; Instituto Politécnico Nacional, Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Legaria 694, Colonia Irrigación, CP 11500, México, DF

In this work a combined thermoacoustic and thermoreflectance set-up was designed for imaging biased microelectronic circuits. In particular, it was used with polycrystalline silicon resistive tracks grown on a monocrystalline Si substrate mounted on a test chip. Thermoreflectance images, obtained by scanning a probe laser beam on the sample surface, clearly show the regions periodically heated by Joule effect, which are associated to the electric current distribution in the circuit. The thermoacoustic signal, detected by a pyroelectric/piezoelectric sensor beneath the chip, also discloses the Joule contribution of the whole sample. However, additional information emerges when a non-modulated laser beam ismore » focused on the sample surface in a raster scan mode allowing imaging of the sample. The distribution of this supplementary signal is related to the voltage distribution along the circuit.« less

Crustal structure beneath western and eastern Iceland from surface waves and receiver functions

USGS Publications Warehouse

Du, Z.; Foulger, G.R.; Julian, B.R.; Allen, R.M.; Nolet, G.; Morgan, W.J.; Bergsson, B.H.; Erlendsson, P.; Jakobsdottir, S.; Ragnarsson, S.; Stefansson, R.; Vogfjord, K.

2002-01-01

We determine the crustal structures beneath 14 broad-band seismic stations, deployed in western, eastern, central and southern Iceland, using surface wave dispersion curves and receiver functions. We implement a method to invert receiver functions using constraints obtained from genetic algorithm inversion of surface waves. Our final models satisfy both data sets. The thickness of the upper crust, as defined by the velocity horizon Vs = 3.7 km s-1, is fairly uniform at ???6.5-9 km beneath the Tertiary intraplate areas of western and eastern Iceland, and unusually thick at 11 km beneath station HOT22 in the far south of Iceland. The depth to the base of the lower crust, as defined by the velocity horizon Vs = 4.1 km s-1 is ???20-26 km in western Iceland and ???27-33 km in eastern Iceland. These results agree with those of explosion profiles that detect a thinner crust beneath western Iceland than beneath eastern Iceland. An earlier report of a substantial low-velocity zone beneath the Middle Volcanic Zone in the lower crust is confirmed by a similar observation beneath an additional station there. As was found in previous receiver function studies, the most reliable feature of the results is the clear division into an upper sequence that is a few kilometres thick where velocity gradients are high, and a lower, thicker sequence where velocity gradients are low. The transition to typical mantle velocities is variable, and may range from being very gradational to being relatively sharp and clear. A clear Moho, by any definition, is rarely seen, and there is thus uncertainty in estimates of the thickness of the crust in many areas. Although a great deal of seismic data are now available constraining the structures of the crust and upper mantle beneath Iceland, their geological nature is not well understood.

Depth variations of P-wave azimuthal anisotropy beneath East Asia

NASA Astrophysics Data System (ADS)

Wei, W.; Zhao, D.; Xu, J.

2017-12-01

We present a new P-wave anisotropic tomographic model beneath East Asia by inverting a total of 1,488,531 P wave arrival-time data recorded by the regional seismic networks in East Asia and temporary seismic arrays deployed on the Tibetan Plateau. Our results provide important new insights into the subducting Indian, Pacific and Philippine Sea plates and mantle dynamics in East Asia. Our tomographic images show that the northern limit of the subducting Indian plate has reached the Jinsha River suture in eastern Tibet. A striking variation of P-wave azimuthal anisotropy is revealed in the Indian lithosphere: the fast velocity direction (FVD) is NE-SW beneath the Indian continent, whereas the FVD is arc parallel beneath the Himalaya and Tibetan Plateau, which may reflect re-orientation of minerals due to lithospheric extension, in response to the India-Eurasia collision. The FVD in the subducting Philippine Sea plate beneath the Ryukyu arc is NE-SW(trench parallel), which is consistent with the spreading direction of the West Philippine Basin during its initial opening stage, suggesting that it may reflect the fossil anisotropy. A circular pattern of FVDs is revealed around the Philippine Sea slab beneath SE China. We suggest that it reflects asthenospheric strain caused by toroidal mantle flow around the edge of the subducting slab. We find a striking variation of the FVD with depth in the subducting Pacific slab beneath the Northeast Japan arc. It may be caused by slab dehydration that changed elastic properties of the slab with depth. The FVD in the mantle wedge beneath the Northeast Japan and Ryukyu arcs is trench normal, which reflects subduction-induced convection. Beneath the Kuril and Izu-Bonin arcs where oblique subduction occurs, the FVD in the mantle wedge is nearly normal to the moving direction of the downgoing Pacific plate, suggesting that the oblique subduction together with the complex slab morphology have disturbed the mantle flow.

Pad A Main Flame Deflector Sensor Data and Evaluation

NASA Technical Reports Server (NTRS)

Parlier, Christopher R.

2011-01-01

Space shuttle launch pads use flame deflectors beneath the vehicle to channel hot gases away from the vehicle. Pad 39 A at the Kennedy Space Center uses a steel structure coated with refractory concrete. The solid rocket booster plume is comprised of gas and molten alumina oxide particles that erodes the refractory concrete. During the beginning of the shuttle program the loads for this system were never validated with a high level of confidence. This paper presents a representation of the instrumentation data collected and follow on materials science evaluation of the materials exposed to the SRB plume. Data collected during STS-133 and STS-134 will be presented that support the evaluation of the components exposed to the SRB plume.

Application of hydrogeology and groundwater-age estimates to assess the travel time of groundwater at the site of a landfill to the Mahomet Aquifer, near Clinton, Illinois

USGS Publications Warehouse

Kay, Robert T.; Buszka, Paul M.

2016-03-02

The U.S. Geological Survey used interpretations of hydrogeologic conditions and tritium-based groundwater age estimates to assess the travel time of groundwater at a landfill site near Clinton, Illinois (the “Clinton site”) where a chemical waste unit (CWU) was proposed to be within the Clinton landfill unit #3 (CLU#3). Glacial deposits beneath the CWU consist predominantly of low-permeability silt- and clay-rich till interspersed with thin (typically less than 2 feet in thickness) layers of more permeable deposits, including the Upper and Lower Radnor Till Sands and the Organic Soil unit. These glacial deposits are about 170 feet thick and overlie the Mahomet Sand Member of the Banner Formation. The Mahomet aquifer is composed of the Mahomet Sand Member and is used for water supply in much of east-central Illinois.Eight tritium analyses of water from seven wells were used to evaluate the overall age of recharge to aquifers beneath the Clinton site. Groundwater samples were collected from six monitoring wells on or adjacent to the CLU#3 that were open to glacial deposits above the Mahomet aquifer (the upper and lower parts of the Radnor Till Member and the Organic Soil unit) and one proximal production well (approximately 0.5 miles from the CLU#3) that is screened in the Mahomet aquifer. The tritium-based age estimates were computed with a simplifying, piston-flow assumption: that groundwater moves in discrete packets to the sampled interval by advection, without hydrodynamic dispersion or mixing.Tritium concentrations indicate a recharge age of at least 59 years (pre-1953 recharge) for water sampled from deposits below the upper part of the Radnor Till Member at the CLU#3, with older water expected at progressively greater depth in the tills. The largest tritium concentration from a well sampled by this study (well G53S; 0.32 ± 0.10 tritium units) was in groundwater from a sand deposit in the upper part of the Radnor Till Member; the shallowest permeable unit sampled by this study. That result indicated that nearly all groundwater sampled from well G53S entered the aquifer as recharge before 1953. Tritium was detected in a trace concentration in one sample from a second monitoring well open to the upper part of the Radnor Till Member (well G07S; 0.11 ± 0.09 tritium units), and not detected in samples collected from two monitoring wells open to a sand deposit in the lower part of the Radnor Till Member, from two samples collected from two monitoring wells open to the Organic Soil unit, and in two samples collected from a production well screened in the middle of the Mahomet aquifer (a groundwater sample and a sequential replicate sample). The lack of tritium in five of the six groundwater samples collected from the shallow permeable units beneath CLU#3 site and the two samples from the one Mahomet aquifer well indicates an absence of post-1952 recharge. Groundwater-flow paths that could contribute post-1952 recharge to the lower part of the Radnor Till Member, the Organic Soil unit, or the Mahomet aquifer at the CLU#3 are not indicated by these data.Hypothetical two-part mixtures of tritium-dead, pre-1953 recharge water and decay-corrected tritium concentrations in post-1952 recharge were computed and compared with tritium analyses in groundwater sampled from monitoring wells at the CLU#3 site to evaluate whether tritium concentrations in groundwater could be represented by mixtures involving some post-1952 recharge. Results from the hypothetical two-part mixtures indicate that groundwater from monitoring well (G53S) was predominantly composed of pre-1953 recharge and that if present, younger, post-1955 recharge, contributed less than 2.5 percent to that sample. The hypothetical two-part mixing results also indicated that very small amounts of post-1952 recharge composing less than about 2.5 percent of the sample volume could not be distinguished in groundwater samples with tritium concentrations less than about 0.15 TU.The piston-flow based age of recharge determined from the tritium concentration in the groundwater sample from monitoring well G53S yielded an estimated maximum vertical velocity from the land surface to the upper part of the Radnor Till Member of 0.85 feet per year or less. This velocity, ifassumed to apply to the remaining glacial till deposits above the Mahomet aquifer, indicates that recharge flows through the 170 feet of glacial deposits between the base of the proposed chemical waste unit and the top of the Mahomet aquifer in a minimum of 200 years or longer. Analysis of hydraulic data from the site, constrained by a tritium-age based maximum groundwater velocity estimate, computed minimum estimates of effective porosity that range from about 0.021 to 0.024 for the predominantly till deposits above the Mahomet aquifer.Estimated rates of transport of recharge from land surface to the Mahomet aquifer for the CLU#3 site computed using the Darcy velocity equation with site-specific data were about 260 years or longer. The Darcy velocity-based estimates were computed using values that were based on tritium data, estimates of vertical velocity and effective porosity and available site-specific data. Solution of the Darcy velocity equation indicated that maximum vertical groundwater velocities through the deposits above the aquifer were 0.41 or 0.61 feet per year, depending on the site-specific values of vertical hydraulic conductivity (laboratory triaxial test values) and effective porosity used for the computation. The resulting calculated minimum travel times for groundwater to flow from the top of the Berry Clay Member (at the base of the proposed chemical waste unit) to the top of the Mahomet aquifer ranged from about 260 to 370 years, depending on the velocity value used in the calculation. In comparison, plausible travel times calculated using vertical hydraulic conductivity values from a previously published regional groundwater flow model were either slightly less than or longer than those calculated using site data and ranged from 230 to 580 years.Tritium data from 1996 to 2011 USGS regional sampling of groundwater from domestic wells in the confined part of the Mahomet aquifer—which are 2.5 to about 40 miles from the Clinton site—were compared with site-specific data from a production well at the Clinton site. Tritium-based groundwater-age estimates indicated predominantly pre- 1953 recharge dates for USGS and other prior regional samples of groundwater from domestic wells in the Mahomet aquifer. These results agreed with the tritium-based, pre-1953 recharge age estimated for a groundwater sample and a sequential replicate sample from a production well in the confined part of the Mahomet aquifer beneath the Clinton site.The regional tritium-based groundwater age estimates also were compared with pesticide detections in samples from distal domestic wells in the USGS regional network that are about 2.5 to 40 miles from the Clinton site to identify whether very small amounts of post-1952 recharge have in places reached confined parts of the Mahomet aquifer at locations other than the Clinton site in an approximately 2,000 square mile area of the Mahomet aquifer. Very small amounts of post-1952 recharge were defined in this analysis as less than about 2.5 percent of the total recharge contributing to a groundwater sample, based on results from the two-part mixing analysis of tritium data from the Clinton site. Pesticide-based groundwater-age estimates based on 22 detections of pesticides (13 of these detections were estimated concentrations), including atrazine, deethylatrazine (2-Chloro-4-isopropylamino-6-amino- s-triazine), cyanazine, diazinon, metolachlor, molinate, prometon, and trifluralin in groundwater samples from 10 domestic wells 2.5 to about 40 miles distant from the Clinton site indicate that very small amounts of post-1956 to post-1992 recharge can in places reach the confined part of the Mahomet aquifer in other parts of central Illinois. The relative lack of tritium in these samples indicate that the amounts of post-1956 to post-1992 recharge contributing to the 10 domestic wells were a very small part of the overall older groundwater sampled from those wells.The flow process by which very small amounts of pesticide-bearing groundwater reached the screened intervals of the 10 domestic wells could not be distinguished between well-integrity related infiltration and natural hydrogeologic features. Potential explanations include: (1) infiltration through man-made avenues in or along the well, (2) flow of very small amounts of post-1956 to post-1992 recharge through sparsely distributed natural permeable aspects of the glacial till and diluted by mixing with older groundwater, or (3) a combination of both processes.Presuming the domestic wells sampled by the USGS in 1996–2011 in the regional study of the confined part of the Mahomet aquifer are adequately sealed and produce groundwater that is representative of aquifer conditions, the regional tritium and pesticide-based groundwater-age results indicate substantial heterogeneity in the glacial stratigraphy above the Mahomet aquifer. The pesticide-based groundwater-age estimates from the domestic wells distant from the Clinton site also indicate that parts of the Mahomet aquifer with the pesticide detections can be susceptible to contaminant sources at the land surface. The regional pesticide and tritium results from the domestic wells further indicate that a potential exists for possible contaminants from land surface to be transported through the glacial drift deposits that confine the Mahomet aquifer in other parts of central Illinois at faster rates than those computed for recharge at the Clinton site, including CLU#3. This analysis indicates the potential value of sub-microgram-per-liter level concentrations of land-use derived indicators of modern recharge to indicate the presence of very small amounts of modern, post-1952 age recharge in overall older, pre-1953 age groundwater.

VIS/NIR Spectroscopy to determine the spatial variation of the weathering degree in Paleogene clay soil - London Clay Formation

NASA Astrophysics Data System (ADS)

Nasser, Mohammed; Gibson, Andy, ,, Dr; Koor, Nick, ,, Dr; Gale, Professor Andy; Huggett, Jenny, ,, Dr; Branch, Steve

2017-04-01

The London Clay Formation (LCF) which underlies much of South-East England is hugely important as a construction medium. However, its geotechnical performance (shear strength, compressive strength, shrink-swell behaviour, etc. ) is greatly affected by its degree of weathering. Despite this importance, little attention has been focussed on a robust method to define and measure its degree of weathering. This is perhaps a result of a well-known colour change from bluish-grey to brown that accompanies 'weathering' and considered to be the result of oxidisation (Chandler and Apted 1988). Through wide experience, this definition is normally effective, but it is perhaps subjective and reliant on the experience of the investigator and the ability to observe samples or exposures. More objective investigation, typically using SEM is not normally economically feasible or expedient for construction works. We propose a simple, robust method to characterise the degree of weathering in the LCF using reflective or Visible-Near-InfraRed-Spectroscopy (VNIRS). 24 samples were extracted from 2 boreholes drilled in the Hampstead area of London to depths of 12 m within the uppermost Claygate Member of the LCF. VNIRS spectra (350-2500 nm) were measured from all samples and compared with XRD, XRF, SEM and PSD results on the same samples. Results show increased magnitude of absorption features related to clay mineralogy around 1400, 1900 and 2200 nm to a depth of 5 m beneath ground level. Beneath this depth, the absorption features show little variation. SEM analyses show corresponding changes in the degradation of pyrite crystals and individual clay (illite/smectite). These preliminary results show that there is a good potential for VNIRS spectroscopy to determine the variation of weathering in the LCF.

Multidisciplinary Investigations of Submarine Flow to Biscayne Bay, Florida

NASA Astrophysics Data System (ADS)

Halley, R. B.; Reich, C. D.; Swarzenski, P. W.; Langevin, C. D.

2005-05-01

Biscayne Bay and Biscayne National Park (BNP) are located next to the Miami-Dade urban complex and are adjacent to the Dade County South Dade Landfill Facility and the Miami-Dade Water and Sewer South District Plant. The base of the landfill is lined to separate it from the underlying Miami Limestone, the host rock for the surficial Biscayne Aquifer. The sewage-treatment facility injects treated sewage into the lower Florida Aquifer (750 m) that is overlain by an aquitard termed the Middle Confining Unit (450 m). The Biscayne Aquifer (up to 50 m thick) borders the western margin of BNP, and the Floridan Aquifer underlies the entire park. There is concern about leakage of contaminated aquifer water into BNP and its potential effects on water quality. Groundwater flux to Biscayne Bay is being studied using pressure measurements and geochemical analyses from submarine wells, electromagnetic seepage meters, streaming resistivity profiling, and local and regional model simulations. Both seepage meters and water analyses provide point information that can be placed into the regional context provided by flow models and geochemical and geophysical profiling, which, in turn, constrain the groundwater contribution. Water samples were collected approximately quarterly from August 2002 until March 2004 from submarine wells along a transect through Biscayne Bay and across the reef to the shelf edge. Samples were analyzed for conductivity (salinity), dissolved oxygen, temperature, redox potential, nutrients, metals, strontium isotopes, radon, sulfate, and wastewater compounds. Low-salinity water was identified from nearshore wells and indicates seepage from the Biscayne Aquifer and/or surface-water intrusion into the rocks along western Biscayne Bay. Analyses of water samples (n = 109) collected from wells across the Florida shelf show no consistent evidence of wastewater contaminants occurring in groundwater beneath BNP. No significant leakage from the Floridan Aquifer (characterized by low strontium-isotope ratios) was detected in the wells. The groundwater beneath the shelf can be characterized as reduced seawater, modified by microbial respiration to remove oxygen, and interacting with sediments and minerals in the host limestone. The data from submarine well samples are consistent with groundwater model results that indicate a narrow zone of discharge along the western margin of Biscayne Bay. This zone varies in width from 100 to 1000 m along the coast. A seepage meter placed in this zone during March 2004 recorded an average flow of 23 cm/day. Submarine discharge is estimated to be about 6% of the surface-water flow to Biscayne Bay, and almost all of this is in the northern half of the bay, where shoreline and water-table elevations are greatest. Saltwater intrusion extends farther inland in the southern portion of the bay, where water-table and coastal elevations are low. Shoreline-parallel radon-222 profiles also indicate more seepage in the north than south, but suggest low-salinity water extends between 1 and 2 km offshore. Resistivity profiling provided a fourth technique (along with wells, models, and radon) that documents low-salinity water along the coast, particularly toward the northern bay. Resistivity is the only methodology that indicates presence of brackish water 5 km offshore, an observation that requires verification. Interdisciplinary approaches that estimate submarine flow to this tropical estuary are helping reinforce observations made by complimentary methods, while clearly identifying other observations as worthy of further investigation and verification.

Laser Speckle Imaging of Blood Flow Beneath Static Scattering Media

NASA Astrophysics Data System (ADS)

Regan, Caitlin Anderson

Laser speckle imaging (LSI) is a wide-field optical imaging technique that provides information about the movement of scattering particles in biological samples. LSI is used to create maps of relative blood flow and perfusion in samples such as the skin, brain, teeth, gingiva, and other biological tissues. The presence of static, or non-moving, optical scatterers affects the ability of LSI to provide true quantitative and spatially resolved measurements of blood flow. With in vitro experiments using tissue-simulating phantoms, we determined that temporal analysis of raw speckle image sequences improved the quantitative accuracy of LSI to measure flow beneath a static scattering layer. We then applied the temporal algorithm to assess the potential of LSI to monitor oral health. We designed and tested two generations of miniature LSI devices to measure flow in the pulpal chamber of teeth and in the gingiva. Our preliminary clinical pilot data indicated that speckle contrast may correlate with gingival health. To improve visualization of subsurface blood vessels, we developed a technique called photothermal LSI. We applied a short pulse of laser energy to selectively perturb the motion of red blood cells, increasing the signal from vasculature relative to the surroundings. To study the spectral and depth dependence of laser speckle contrast, we developed a Monte Carlo model of light and momentum transport to simulate speckle contrast. With an increase in the thickness of the overlying static-scattering layer, we observed a quadratic decrease in the quantity of dynamically scattered light collected by the detector. We next applied the model to study multi-exposure speckle imaging (MESI), a method that purportedly improves quantitative accuracy of subsurface blood flow measurements. We unexpectedly determined that MESI faced similar depth limitations as conventional LSI, findings that were supported by in vitro experimental data. Finally, we used the model to study the effects of epidermal melanin absorption on LSI, and demonstrated that speckle contrast is less sensitive to varying melanin content than reflectance. We then proposed a two-wavelength measurement protocol that may enable melanin-independent LSI measurements of blood flow in patients with varying skin types. In conclusion, through in vitro and in silico experiments, we were able to further the understanding of the depth dependent origins of laser speckle contrast as well as the inherent limitations of this technology.

Mare volcanism in the Taurus-Littrow region

NASA Technical Reports Server (NTRS)

Delano, J. W.

1992-01-01

The products of mare volcanism at Taurus-Littrow occur in the form of crystalline basalts and volcanic glass beads. Both categories of samples define a compositionally diverse, but petrogenetically unrelated, suite of magmas derived by partial melting of a heterogenous, differentiated mantle beneath the region of the Apollo 17 landing site. This is a brief review of what is known and what is not known about mare volcanism at this location on the Moon.

Evidence for magmatic underplating and partial melt beneath the Canary Islands derived using teleseismic receiver functions

NASA Astrophysics Data System (ADS)

Lodge, A.; Nippress, S. E. J.; Rietbrock, A.; García-Yeguas, A.; Ibáñez, J. M.

2012-12-01

In recent years, an increasing number of studies have focussed on resolving the internal structure of ocean island volcanoes. Traditionally, active source seismic experiments have been used to image the volcano edifice. Here we present results using the analysis of compressional to shear (P to S) converted seismic phases from teleseismic events, recorded by stations involved in an active source experiment "TOM-TEIDEVS" (Ibáñez et al., 2008), on the island of Tenerife, Canary Islands. We supplement this data with receiver function (RF) analysis of seismograms from the Canary Islands of Lanzarote and La Palma, applying the extended-time multitaper frequency domain cross-correlation estimation method (Helffrich, 2006). We use the neighbourhood inversion approach of Sambridge (1999a,b) to model the RFs and our results indicate magmatic underplating exists beneath all three islands, ranging from 2 to 8 km, but showing no clear correlation with the age of the island. Beneath both La Palma and Tenerife, we find localized low velocity zones (LVZs), which we interpret as due to partial melt, supported by their correlation with the location of historical earthquakes (La Palma) and recent earthquakes (Tenerife). For Lanzarote, we do not sample the most recently volcanically active region and find no evidence for a LVZ. Instead, we find a simple gradational velocity structure, with discontinuities at ˜4, 10 and 18 km depth, in line with previous studies.

Seismic structures beneath Popocatepetl (Mexico) and Gorely (Kamchatka) volcanoes derived from passive tomography studies

NASA Astrophysics Data System (ADS)

Kuznetsov, Pavel; Koulakov, Ivan

2014-05-01

A number of active volcanoes are observed in different parts of the world, and they attract great interest of scientists. Comparing their characteristics helps in understanding the origin and mechanisms of their activity. One of the most effective methods for studying the deep structure beneath volcanoes is passive source seismic tomography. In this study we present results of tomographic inversions for two active volcanoes located in different parts of the world: Popocatepetl (Mexico) and Gorely (Kamchatka, Russia). In the past century both volcanoes were actively erupted that explains great interest to their detailed investigations. In both cases we made the full data analysis starting from picking the arrival times from local events. In the case of the Popocatepetl study, a temporary seismological network was deployed by GFZ for the period from December 1999 to July 2000. Note that during this period there were a very few events recorded inside the volcano. Most of recorded earthquakes occurred in surrounding areas and they probably have the tectonic nature. We performed a special analysis to ground the efficiency of using these data for studying seismic structure beneath the network installed on the volcano. The tomographic inversion was performed using the LOTOS code by Koulakov (2009). Beneath the Popocatepetl volcano we have found a zone of strong anti-correlation between P- and S-velocities that leaded to high values of Vp/Vs ratio. Similar features were found for some other volcanoes in previous studies. We interpret these anomalies as zones of high content of fluids and melts that are related to active magma sources. For the case of Gorely volcano we used the data of a temporary network just deployed in summer 2013 by our team from IPGG, Novosibirsk. Luckily, during the field works, the volcano started to manifest strong seismic activity. In this period, 100 - 200 volcanic events occurred daily. We collected the continuous seismic records from 20 stations for 5-7 days that gives us the possibility to locate several hundreds of events and to build a preliminary seismic model beneath the Gorely volcano. We found a zone of low S-velocity located beneath the SE flank of the volcano, just between the Gorely and Mutnovsky volcanoes. This may serve as an argument for feeding these volcanoes from a single source. Although Popocatepetl and Gorely volcanoes are considerably different in their size and eruption characteristics, we found some similar features in the seismic structures, such as anti-correlation of P- and S- anomalies and high Vp/Vs ratio patterns below summits. This provides common patterns that give us the keys for understanding the general mechanism of working the volcanic systems. This study was partly supported by the projects #7.3 of BES RAS, IP SB RAS #20 and IP SB-FEB RAS #42

Lithospheric instability and the source of the Cameroon Volcanic Line: Evidence from Rayleigh wave phase velocity tomography

DOE PAGES

Adams, Aubreya N.; Wiens, Douglas A.; Nyblade, Andrew A.; ...

2015-03-24

The Cameroon Volcanic Line (CVL) is a 1800 km long volcanic chain, extending SW-NE from the Gulf of Guinea into Central Africa, that lacks the typical age progression exhibited by hot spot-related volcanic tracks. Our study investigates the upper mantle seismic structure beneath the CVL and surrounding regions to constrain the origin of volcanic lines that are poorly described by the classic plume model. Rayleigh wave phase velocities are measured at periods from 20 to 182 s following the two-plane wave methodology, using data from the Cameroon Seismic Experiment, which consists of 32 broadband stations deployed between 2005 and 2007.more » These phase velocities are then inverted to build a model of shear wave velocity structure in the upper mantle beneath the CVL. Our results show that phase velocities beneath the CVL are reduced at all periods, with average velocities beneath the CVL deviating more than –2% from the regional average and +4% beneath the Congo Craton. This distinction is observed for all periods but is less pronounced for the longest periods measured. Inversion for shear wave velocity structure indicates a tabular low velocity anomaly directly beneath the CVL at depths of 50 to at least 200 km and a sharp vertical boundary with faster velocities beneath the Congo Craton. Finally, these observations demonstrate widespread infiltration or erosion of the continental lithosphere beneath the CVL, most likely caused by mantle upwelling associated with edge-flow convection driven by the Congo Craton or by lithospheric instabilities that develop due to the nearby edge of the African continent.« less

Spatial distribution of grape root borer (Lepidoptera: Sesiidae) infestations in Virginia vineyards and implications for sampling.

PubMed

Rijal, J P; Brewster, C C; Bergh, J C

2014-06-01

Grape root borer, Vitacea polistiformis (Harris) (Lepidoptera: Sesiidae) is a potentially destructive pest of grape vines, Vitis spp. in the eastern United States. After feeding on grape roots for ≍2 yr in Virginia, larvae pupate beneath the soil surface around the vine base. Adults emerge during July and August, leaving empty pupal exuviae on or protruding from the soil. Weekly collections of pupal exuviae from an ≍1-m-diameter weed-free zone around the base of a grid of sample vines in Virginia vineyards were conducted in July and August, 2008-2012, and their distribution was characterized using both nonspatial (dispersion) and spatial techniques. Taylor's power law showed a significant aggregation of pupal exuviae, based on data from 19 vineyard blocks. Combined use of geostatistical and Spatial Analysis by Distance IndicEs methods indicated evidence of an aggregated pupal exuviae distribution pattern in seven of the nine blocks used for those analyses. Grape root borer pupal exuviae exhibited spatial dependency within a mean distance of 8.8 m, based on the range values of best-fitted variograms. Interpolated and clustering index-based infestation distribution maps were developed to show the spatial pattern of the insect within the vineyard blocks. The temporal distribution of pupal exuviae showed that the majority of moths emerged during the 3-wk period spanning the third week of July and the first week of August. The spatial distribution of grape root borer pupal exuviae was used in combination with temporal moth emergence patterns to develop a quantitative and efficient sampling scheme to assess infestations.

Mantle flow beneath Arabia offset from the opening Red Sea

NASA Astrophysics Data System (ADS)

Chang, Sung-Joon; Merino, Miguel; Van der Lee, Suzan; Stein, Seth; Stein, Carol A.

2011-02-01

Continental rifting involves a poorly understood sequence of lithospheric stretching, volcanism, and mantle flow that evolves to seafloor spreading. We present new insight from inversion of seismic traveltimes and waveforms beneath Arabia and surroundings. Low velocities occur beneath the southern Red Sea and Gulf of Aden, consistent with active spreading. However, hot material extends not below the northern Red Sea, but is offset eastward beneath Arabia, showing mantle flow from the Afar hotspot. The location of this channel beneath volcanic rocks erupted since rifting began 30 million years ago indicates that flow moves with Arabia. We propose that the absence of seafloor spreading in the northern Red Sea reflects the offset flow. This geometry may evolve to spreading in the Northern Red Sea, rifting of Arabia, or both. This situation has aspects of both active and passive rifting, showing that both can occur before coalescing to seafloor spreading.

Mantle structure beneath the western edge of the Colorado Plateau

USGS Publications Warehouse

Sine, C.R.; Wilson, D.; Gao, W.; Grand, S.P.; Aster, R.; Ni, J.; Baldridge, W.S.

2008-01-01

Teleseismic traveltime data are inverted for mantle Vp and Vs variations beneath a 1400 km long line of broadband seismometers extending from eastern New Mexico to western Utah. The model spans 600 km beneath the moho with resolution of ???50 km. Inversions show a sharp, large-magnitude velocity contrast across the Colorado Plateau-Great Basin transition extending ???200 km below the crust. Also imaged is a fast anomaly 300 to 600 km beneath the NW portion of the array. Very slow velocities beneath the Great Basin imply partial melting and/or anomalously wet mantle. We propose that the sharp contrast in mantle velocities across the western edge of the Plateau corresponds to differential lithospheric modification, during and following Farallon subduction, across a boundary defining the western extent of unmodified Proterozoic mantle lithosphere. The deep fast anomaly corresponds to thickened Farallon plate or detached continental lithosphere at transition zone depths. Copyright 2008 by the American Geophysical Union.

Groundwater and Thaw Legacy of a Large Paleolake in Taylor Valley, East Antarctica as Evidenced by Airborne Electromagnetic and Sedimentological Techniques

NASA Astrophysics Data System (ADS)

Doran, P. T.; Myers, K. F.; Foley, N.; Tulaczyk, S. M.; Dugan, H. A.; Auken, E.; Mikucki, J.; Virginia, R. A.

2017-12-01

The McMurdo Dry Valleys (MDVs) in east Antarctica contain a number of perennial ice-covered lakes fed by ephemeral meltwater streams. Lake Fryxell in Taylor Valley, is roughly 5.5 km long and approximately 22 m deep. Paleodeltas and paleoshorelines throughout Fryxell Basin provide evidence of significant lake level change occurring since the Last Glacial Maximum (LGM). During the LGM, grounded ice in the Ross Sea extended into the eastern portion of Taylor Valley, creating a large ice dammed paleolake. Glacial Lake Washburn (GLW) was roughly 300 m higher than modern day Lake Fryxell and its formation and existence has been debated. In this study, we use Geographical Information System and remote sensing techniques paired with regional resistivity data to provide new insight into the paleohydrology of the region. The existence of GLW is supported by new findings of a deep groundwater system beneath Lake Fryxell, which is interpreted as the degrading thaw bulb of GLW. Airborne resistivity data collected by SkyTEM, a time-domain airborne electromagnetic sensor system was used to map groundwater systems in the lake basin. Subsurface characteristics can be inferred from the relationship of resistivity to temperature, salinity, porosity, and degree of saturation. A large low resistivity region indicative of liquid water extends hundreds of meters away from the modern lake extent which is consistent with the presence of a degrading thaw bulb from GLW. As lake level in Fryxell Basin fell to modern levels, the saturated sediment beneath the lake began to freeze as it became exposed to low atmospheric temperatures. We hypothesize that this process is ongoing and will continue until equilibrium is reached between the geothermal gradient and atmospheric temperatures. Though liquid groundwater systems were previously thought to be minimal or nonexistent in the MDVs, regional resistivity data now show that extensive groundwater reservoirs exist beneath these lakes. In addition to the implications for the paleolake history of GLW, the presence of deep groundwater systems beneath MDV lakes has important implications for hydrologic and ecosystem connectivity in an environment which is largely driven by the availability of liquid water.

Seismic evidence of the lithosphere-asthenosphere boundary beneath Izu-Bonin area

NASA Astrophysics Data System (ADS)

Cui, H.; Gao, Y.; Zhou, Y.

2016-12-01

The lithosphere-asthenosphere boundary (LAB), separating the rigid lithosphere and the ductile asthenosphere layers, is the seismic discontinuity with the negative velocity contrast of the Earth's interior [Fischer et al., 2010]. The LAB has been also termed the Gutenberg (G) discontinuity that defines the top of the low velocity zone in the upper mantle [Gutenberg, 1959; Revenaugh and Jordan, 1991]. The seismic velocity, viscosity, resistivity and other physical parameters change rapidly with the depths across the boundary [Eaton et al., 2009]. Seismic detections on the LAB in subduction zone regions are of great help to understand the interactions between the lithosphere and asthenosphere layers and the geodynamic processes related with the slab subductions. In this study, the vertical broadband waveforms are collected from three deep earthquake events occurring from 2000 to 2014 with the focal depths of 400 600 km beneath the Izu-Bonin area. The waveform data is processed with the linear slant stack method [Zang and Zhou, 2002] to obtain the vespagrams in the relative travel-time to slowness domain and the stacked waveforms. The sP precursors reflected on the LAB (sLABP), which have the negative polarities with the amplitude ratios of 0.17 0.21 relative to the sP phases, are successfully extracted. Based on the one-dimensional modified velocity model (IASP91-IB), we obtain the distributions for six reflected points of the sLABP phases near the source region. Our results reveal that the LAB depths range between 58 and 65 km beneath the Izu-Bonin Arc, with the average depth of 62 km and the small topography of 7 km. Compared with the results of the tectonic stable areas in Philippine Sea [Kawakatsu et al., 2009; Kumar and Kawakatsu, 2011], the oceanic lithosphere beneath the Izu-Bonin Arc shows the obvious thinning phenomena. We infer that the lithospheric thinning is closely related with the partial melting, which is caused by the volatiles continuously released from the subducted western Pacific slab in deep Earth, and the strong erosions of the small-scale mantle convection in the back-arc mantle wedge.

The crustal structure and tectonic development of the continental margin of the Amundsen Sea Embayment, West Antarctica: implications from geophysical data

NASA Astrophysics Data System (ADS)

Kalberg, Thomas; Gohl, Karsten

2014-07-01

The Amundsen Sea Embayment of West Antarctica represents a key component in the tectonic history of Antarctic-New Zealand continental breakup. The region played a major role in the plate-kinematic development of the southern Pacific from the inferred collision of the Hikurangi Plateau with the Gondwana subduction margin at approximately 110-100 Ma to the evolution of the West Antarctic Rift System. However, little is known about the crustal architecture and the tectonic processes creating the embayment. During two `RV Polarstern' expeditions in 2006 and 2010 a large geophysical data set was collected consisting of seismic-refraction and reflection data, ship-borne gravity and helicopter-borne magnetic measurements. Two P-wave velocity-depth models based on forward traveltime modelling of nine ocean bottom hydrophone recordings provide an insight into the lithospheric structure beneath the Amundsen Sea Embayment. Seismic-reflection data image the sedimentary architecture and the top-of-basement. The seismic data provide constraints for 2-D gravity modelling, which supports and complements P-wave modelling. Our final model shows 10-14-km-thick stretched continental crust at the continental rise that thickens to as much as 28 km beneath the inner shelf. The homogenous crustal architecture of the continental rise, including horst and graben structures are interpreted as indicating that wide-mode rifting affected the entire region. We observe a high-velocity layer of variable thickness beneath the margin and related it, contrary to other `normal volcanic type margins', to a proposed magma flow along the base of the crust from beneath eastern Marie Byrd Land-West Antarctica to the Marie Byrd Seamount province. Furthermore, we discuss the possibility of upper mantle serpentinization by seawater penetration at the Marie Byrd Seamount province. Hints of seaward-dipping reflectors indicate some degree of volcanism in the area after break-up. A set of gravity anomaly data indicate several phases of fully developed and failed rift systems, including a possible branch of the West Antarctic Rift System in the Amundsen Sea Embayment.

Lithospheric structure beneath the central and western North China Craton and adjacent regions from S-receiver function imaging

NASA Astrophysics Data System (ADS)

Yinshuang, A.; Zhang, Y.; Chen, L.

2016-12-01

The central and western NCC(CWNCC) only experienced localized lithospheric modification and has remained relatively stable since the Pre-Cambrian in contrast to the fundamental destruction in the east. For better unraveling the tectonic evolution and dynamics of CWNCC, detailed knowledge of lithospheric structure is thus important. However, most of the available seismological observations are dominated by regional seismic tomography and the resolutions are rather low due to the limited data coverage or intrinsic limitation of the methods. S receiver function(RF) contains information from deep velocity discontinuities and is free from the interference of crustal multiples, so it is widely used in subcontinental lithospheric structural studies. We collected teleseismic data from 340 broadband stations in CWNCC, and adopted 2-D wave equation-based poststack migration method to do S-receiver function CCP imaging. Finally, we get 8 migrated profile images in CWNCC and adjacent areas and integrate them for an overview. The most prominent feature of the LAB beneath central NCC is an sudden subsidence to 160km in the southern portion, and the dimension and extension of this deep anomaly is correlated to the lithosphere in Ordos, so we interpret it as a remnant cratonic mantle root. The LAB beneath western NCC can extend to the depth of 150-180 km but appears laterally variable. Western Ordos becomes shallower than its eastern counterpart and there are two obvious deep anomalies beneath the eastern Ordos, divided by a geological boundary at 37°N, which reflects that the lithosphere of Ordos is not so homogeneous or rigid as people thought before. Furthermore, a negative velocity discontinuity is widely identified at the depth of 80- 110 km within the thick lithosphere of CWNCC, and the location is spatially coincide with the modified LAB in ENCC. Although the cause of this mid-lithospheric discontinuity(MLD) is still controversial, mechanically, it may indicate an ancient, weak layer within the overall strong cratonic lithosphere. Our result is broadly consistent with the previous tomography studies, but shows more detailed information of lithospheric variations,. Moreover, it corroborates the existence of the similar discontinuities at 100 km depth under stable continental regions worldwide.

IRETHERM: The geothermal energy potential of Irish radiothermal granites

NASA Astrophysics Data System (ADS)

Farrell, Thomas; Jones, Alan; Muller, Mark; Feely, Martin; Brock, Andrew; Long, Mike; Waters, Tim

2014-05-01

The IRETHERM project is developing a strategic understanding of Ireland's deep geothermal energy potential through integrated modelling of new and existing geophysical and geological data. One aspect of IRETHERM's research focuses on Ireland's radiothermal granites, where increased concentrations of radioelements provide elevated heat-production (HP), surface heat-flow (SHF) and subsurface temperatures. An understanding of the contribution of granites to the thermal field of Ireland is important to assessing the geothermal energy potential of this low-enthalpy setting. This study focuses on the Galway granite in western Ireland, and the Leinster and the buried Kentstown granites in eastern Ireland. Shallow (<250 m) boreholes were drilled into the exposed Caledonian Leinster and Galway granites as part of a 1980's geothermal project. These studies yielded HP = 2-3 μWm-3 and HF = 80 mWm-2 at the Sally Gap borehole in the Northern Units of the Leinster granite, to the SW of Dublin. In the Galway granite batholith, on the west coast of Ireland, the Costelloe-Murvey granite returned HP = 7 μWm-3 and HF = 77 mWm-2, measured at the Rossaveal borehole. The buried Kentstown granite, 35 km NW of Dublin, has an associated negative Bouguer anomaly and was intersected by two mineral exploration boreholes at depths of 660 m and 490 m. Heat production is measured at 2.4 μWm-3 in core samples taken from the weathered top 30 m of the granite. The core of this study consists of a program of magnetotelluric (MT) and audio-magnetotelluric (AMT) data acquisition across the three granite bodies, over three fieldwork seasons. MT and AMT data were collected at 59 locations along two profiles over the Leinster granite. Preliminary results show that the northern units of the Leinster granite (40 km SW of Dublin) extend to depths of 2-5 km. Preliminary results from the southern profile suggest a greater thickness of granite to a depth of 6-9 km beneath the Tullow pluton, 75 km SW of Dublin. Over the Galway granite, MT and AMT data have been collected at a total of 75 sites (33 consist of only AMT data acquisition, with both MT and AMT recorded at the remaining 42). Preliminary results show a deep resistor extending to depths of 15-20 km beneath the central block, with the resistive upper layer extending to depths of 3.5-7 km west of the Shannawona fault, a major structure that cuts the batholith. MT and AMT data acquired along a profile at 22 locations over the Kentstown granite suggests that this buried granite is at a depth of 400 m beneath the centre of the gravity anomaly. The MT and AMT data will be integrated with gravity and seismic refraction data (in the case of the Leinster granite) to identify deeply penetrating faults, which may provide conduits for hydrothermal fluids, and to produce a robust estimation of the volumetric extent of the granites, which is crucial in defining their geothermal energy potential. Thermal conductivity and geochemical data will be incorporated to constrain the heat contribution of granites to the Irish crust.

Soil temperatures under urban trees and asphalt

Treesearch

Howard G. Halverson; Gordon M. Heisler

1981-01-01

Summer temperatures under trees planted in holes cut through an asphalt cover in a parking lot and in soil beneath the surrounding asphalt were higher than soil temperatures under trees at a control site. Winter minimums were not different, but maximum summer temperature exceeded the control by 3ºC beneath the parking lot trees and up to 10ºC beneath...

Lithospheric Structure Beneath Taiwan From Sp Converted Waves

NASA Astrophysics Data System (ADS)

Glasgow, D.; McGlashan, N.; Brown, L.

2006-12-01

Taiwan is the product of three dimensionally complex interaction between the Eurasian Plate (EP) and the Philippine Sea plate (PSP), with the EP subducting eastward beneath the PSP in southern Taiwan while the PSP subducts northward beneath the EP in northern Taiwan. The structural emplacement of Philippine Arc lithosphere onto Chinese passive margin lithosphere is an exemplar of continental amalgamation, yet there are relatively few contraints on the geometry of lithosphere involved at depth. We have used teleseismic data recorded by the Broadband Array for Taiwan Seismology (BATS) to compute S-to-p wave receiver functions for the Taiwan region to provide new constraints on deep geometries. Moho conversions provide independent new estimates of crustal thickness, which vary from 35 to 55 km across the island in agreement with previous P to S conversion studies and local tomography. More significantly, our results suggest that the lithosphere- asthenosphere boundary (LAB) varies in depth from ca 140 km beneath northeastern Taiwan to ca 120 km beneath central Taiwan to perhaps less than 80 km beneath southern Taiwan. We attribute this along strike variation to the depression and decapitation of the Eurasian plate in the transition to northward subduction of the PSP.

A review of water resources of the Umiat area, northern Alaska

USGS Publications Warehouse

Williams, John R.

1970-01-01

Surface-water supplies from the Colville River, small tributary creeks, and lakes are abundant in summer but limited in winter by low or zero flow in streams and thick ice cover on lakes. Fresh ground water occurs in unfrozen zones in alluvium and in the upper part of bedrock beneath the Colville River and beneath lakes that do not freeze to the bottom in winter. These unfrozen zones, forming depressions in the upper surface of permafrost, are maintained by flow of heat from bodies of surface water into subjacent alluvium and bedrock. Brackish or saline ground water occurs in bedrock beneath as much as 1,055 feet of permafrost in the Arctic foothills and beneath 750 to 800 feet of permafrost beneath low terraces of the Colville River valley. The foothill area is unfavorable for developing supplies of potable ground water because of the great depth to water, predominance of brackish or saline water, and low potential yield of the bedrock. In the Colville River valley, shallow unfrozen alluvium beneath the river and deep lakes will yield abundant year-round supplies of ground water, but the bedrock below permafrost yields less than 10 gpm (gallons per minute) of saline or brackish water.

Icelandic-type crust

USGS Publications Warehouse

Foulger, G.R.; Du, Z.; Julian, B.R.

2003-01-01

Numerous seismic studies, in particular using receiver functions and explosion seismology, have provided a detailed picture of the structure and thickness of the crust beneath the Iceland transverse ridge. We review the results and propose a structural model that is consistent with all the observations. The upper crust is typically 7 ?? 1 km thick, heterogeneous and has high velocity gradients. The lower crust is typically 15-30 ?? 5 km thick and begins where the velocity gradient decreases radically. This generally occurs at the V p ??? 6.5 km s-1 level. A low-velocity zone ??? 10 000 km2 in area and up to ??? 15 km thick occupies the lower crust beneath central Iceland, and may represent a submerged, trapped oceanic microplate. The crust-mantle boundary is a transition zone ???5 ?? 3 km thick throughout which V p increases progressively from ???7.2 to ???8.0 km s-1. It may be gradational or a zone of alternating high- and low-velocity layers. There is no seismic evidence for melt or exceptionally high temperatures in or near this zone. Isostasy indicates that the density contrast between the lower crust and the mantle is only ???90 kg m-3 compared with ???300 kg m-3 for normal oceanic crust, indicating compositional anomalies that are as yet not understood. The seismological crust is ???30 km thick beneath the Greenland-Iceland and Iceland-Faeroe ridges, and eastern Iceland, ???20 km beneath western Iceland, and ???40 km thick beneath central Iceland. This pattern is not what is predicted for an eastward-migrating plume. Low attenuation and normal V p/V s ratios in the lower crust beneath central and southwestern Iceland, and normal uppermost mantle velocities in general, suggest that the crust and uppermost mantle are subsolidus and cooler than at equivalent depths beneath the East Pacific Rise. Seismic data from Iceland have historically been interpreted both in terms of thin-hot and thick-cold crust models, both of which have been cited as supporting the plume hypothesis. This suggests that the plume model for Iceland is an a priori assumption rather than a hypothesis subject to testing. The long-extinct Ontong-Java Plateau, northwest India and Parana??, Brazil large igneous provinces, beneath which mantle plumes are not expected are all underlain by mantle low-velocity bodies similar to that beneath Iceland. A plume interpretation for the mantle anomaly beneath Iceland is thus not required.

A Glimpse at Late Mesozoic to Early Tertiary Offshore Stratigraphy from Wilkes Land, East Antarctica: Results of Strategic Dredging of the Mertz-Ninnis Trough

NASA Astrophysics Data System (ADS)

Schrum, H.; Domack, E.; Desantis, L.; Leventer, A.; McMullen, K.; Escutia, C.

2004-12-01

As early as 1912 Sir Douglas Mawson demonstrated that pre-glacial sedimentary successions could be recovered by seafloor dredging of erosional troughs found offshore, East Antarctica. Since then, little systematic dredging has been undertaken in Antarctica despite indications of outcropping strata exposed along seaward flanks of glacially excavated troughs and the dire need to resolve the nature of preglacial and synglacial strata in this region. During cruise NB Palmer 01-01, three dredges were collected in echelon along the seaward flank of the Mertz-Ninnis Trough, parallel to the Mertz Ice Tongue, in water depths of 900 to 450 m. We combine biostratigraphic (palynologic) and lithologic analyses on sedimentary clasts with multi- and single-channel seismic reflection data collected by the WEGA cruise in 2000. 1359 pebble to cobble sized clasts were collected from three dredges. Of these 15% to 43%, within each dredge, were of sedimentary character, including carbonaceous sandstones with plant macrofossils, black sulfide-rich mudstones, siltstones, lignites, red quartz arenites, arkoses, and diamictites in various states of lithification. Palynomorphs were separated from these sedimentary rocks. We examined eleven individual lithologies, nine of which yielded useful palynological detritus. Of these samples, five yielded palynomorphs distinctive to the Paleogene (i.e. Nothofagus flemingii, Tricolporites spp., Proteacidites spp.); two samples contained only Lower Cretaceous palynomorphs, while three samples provided no stratigraphically useful palynomorph kerogen. We combine these results with multi-channel seismic and multibeam swath mapping to demonstrate that dredged materials represent seafloor outcrop or shallow subcrop of strata beneath a thin glacial till. Our stratigraphic model for these samples is consistent with 62 km of multichannel seismic reflection data (WEGA line W02) showing seaward dipping strata onlapping the basement to the southwest and partly infilling a rifted basin of late Cretaceous age. Seaward dipping reflectors above the syn-rift strata represent post-rift deposits ranging from Paleogene to Quaternary. Included within this stratigraphy are lithified diamictites containing Mesozoic palynomorphs in addition to palynomorphs of Early Tertiary age (including dinoflagellates). Seaward dipping reflectors in the deep axis of the Mertz-Ninnis Trough were not sampled directly by our dredges, but are believed to be Lower Cretaceous siltstones by extrapolation to core DF-79-38, 100 km along strike to the southeast (Domack et al., 1980). Furthermore, the thermal maturity of the lignite samples recovered in our collections suggests that the coal is of Early Tertiary age, as are numerous organic-rich mudstones, which contain Paleogene palynomorphs. These results indicate that sedimentary strata in this portion of the Wilkes Land Margin contain significantly thick (greater than 2.7 km) post-rift (drift phase) marine sequences of both pre- and synglacial character. Strategic dredging is a promising methodology by which to sample stratigraphic succession in a cost effective manner along the East Antarctic margin in the absence of, or preparation for, International Ocean Drilling Projects on the shelf. Domack, E. W., Fairchild, W. W., and Anderson, J. B. (1980) Lower Cretaceous sediment from the East Antarctic continental shelf, Nature, 287, 625-626.

Receiver Functions Imaging of the Moho and LAB in the Southern Caribbean plate boundary and Venezuela

NASA Astrophysics Data System (ADS)

Masy, J.; Levander, A.; Niu, F.

2011-12-01

We have made teleseismic Ps and Sp receiver functions from data recorded from 2003 to 2009 by the permanent national seismic network of Venezuela, the BOLIVAR (Broadband Onshore-offshore Lithospheric Investigation of Venezuela and the Antilles arc Region) and WAVE (Western Array for Venezuela) experiments. The receiver functions show rapid variations in Moho and lithosphere-asthenosphere boundary (LAB) depths both across and along the southern Caribbean plate boundary region. We used a total of 69 events with Mw > 6 occurring at epicentral distances from 30° to 90° for the Ps receiver functions, and 43 events with Mw > 5.7 from 55° to 85° to make Sp receiver functions. For CCP stacking we constructed a 3D velocity model from numerous active source profiles (Schmitz et al., 2001; Bezada et al., 2007; Clark et al., 2008; Guedez, 2008; Magnani et al., 2009), from finite-frequency P wave upper mantle tomography model of Bezada et al., (2010) and the Rayleigh wave tomography model of Miller et al., (2009). The Moho ranges in depth from ~25 km beneath the Caribbean Large Igneous Provinces to ~55 km beneath the Mérida Andes in western Venezuela. These results are consistent with previous receiver functions studies (Niu et al., 2007) and the available active source profiles. Beneath the Maracaibo Block in northwestern Venezuela, we observe a strong positive signal at 40 to 60 km depth dipping ~6° towards the continent. We interpret this as the Moho of the Caribbean slab subducting beneath northernmost South America from the west. Beneath northern Colombia and northwestern Venezuela the top of this slab has been previously inferred from intermediate depth seismicity (Malavé and Suarez, 1995), which indicates a slab dipping between 20° - 30° beneath Lake Maracaibo. Our results could indicate that the slab is tearing beneath Lake Maracaibo as suggested previously by Masy et al. (2011). The deeper (> 100 km depth) part of the slab has been imaged using P-wave tomography (Bezada et al, 2010). Like others we attribute the uplift of the Mérida Andes to flat Caribbean slab subduction (for example Kellogg and Bonini, 1982). In central Venezuela beneath the Cordillera de la Costa we observe a positive signal shallower than the Moho at <30 km depth beneath the entire range. We interpret this as a detachment surface beneath Caribbean & arc terranes thrust onto the SA margin (Bezada et al., 2010). The lithosphere-asthenosphere boundary (LAB) beneath the Mérida Andes is shallow, ~65km depth, and parallels the range. In the plate boundary region under the Cordillera de la Costa the lithosphere is also thin, ~65km, beneath the Cariaco basin the lithosphere thickens to 85 km. In the far east under Serranía del Interior the lithosphere is ~75 km. Cratonic lithosphere thickness varies from 85 to 100 km.

Mantle water contents beneath the Rio Grande Rift (NM, USA): FTIR analysis of Rio Puerco and Kilbourne Hole peridotite xenoliths

NASA Astrophysics Data System (ADS)

Schaffer, L. A.; Peslier, A. H.; Brandon, A. D.; Selverstone, J.

2015-12-01

Peridotite xenoliths from the Rio Grande Rift (RGR) are being analyzed for H2O contents by FTIR as well as for major and trace element compositions. Nine samples are from the Rio Puerco Volcanic Field (RP) which overlaps the central RGR and southeastern Colorado Plateau; seventeen samples are from Kilbourne Hole (KH) in the southern RGR. Spinel Cr# (Cr/(Cr+Al) = 0.08-0.46) and olivine Mg# (Mg/(Mg+Fe) = 0.883-0.911) of samples fall within the olivine-spinel mantle array from [1], an indicator that these are residues of partial melting. Pyroxene H2O contents in KH correlate with bulk rock and pyroxene Al2O3 contents. The KH clinopyroxene rare earth element (REE) variations fit models of 0-13% fractional melting of a primitive upper mantle. Most KH peridotites have bulk-rock light REE depleted patterns, but five are enriched in light REEs consistent with metasomatism. Variation in H2O content seems unrelated to REE enrichment. Metasomatism is seen in RP pyroxenite xenoliths [2] and will be examined in the peridotites studied here. Olivine H2O contents are low (≤20 ppm), and decrease from core to rim within grains. This is likely due to H loss during xenolith transport by the host magma [3]. Diffusion models of H suggest that mantle H2O contents are still preserved in cores of KH olivine, but not those of RP olivine. The average H2O content of Colorado Plateau clinopyroxene (670 ppm) [4] is ~300 ppm higher than RGR clinopyroxene (350 ppm). This upholds the hypothesis that hydration-induced lithospheric melting occurred during flat-slab subduction of the Farallon plate [5]. Numerical models indicate hydration via slab fluids is possible beneath the plateau, ~600 km from the paleo-trench, but less likely ~850 km away beneath the rift [6]. [1]Arai, 1994 CG 113, 191-204.[2]Porreca et al., 2006 Geosp 2, 333-351.[3]Peslier and Luhr, 2006 EPSL 242, 302-319.[4]Li et al., 2008 JGR 113, 1978-2012.[5]Humphreys et al., 2003 Int Geol Rev 45, 575-595.[6]English et al., 2003 EPSL 214, 619-632.

Equatorial origin for Lower Jurassic radiolarian chert in the Franciscan Complex, San Rafael Mountains, southern California

USGS Publications Warehouse

Hagstrum, J.T.; Murchey, B.L.; Bogar, R.S.

1996-01-01

Lower Jurassic radiolarian chert sampled at two localities in the San Rafael Mountains of southern California (???20 km north of Santa Barbara) contains four components of remanent magnetization. Components A, B???, and B are inferred to represent uplift, Miocene volcanism, and subduction/accretion overprint magnetizations, respectively. The fourth component (C), isolated between 580?? and 680??C, shows a magnetic polarity stratigraphy and is interpreted as a primary magnetization acquired by the chert during, or soon after, deposition. Both sequences are late Pliensbachian to middle Toarcian in age, and an average paleolatitude calculated from all tilt-corrected C components is 1?? ?? 3?? north or south. This result is consistent with deposition of the cherts beneath the equatorial zone of high biologic productivity and is similar to initial paleolatitudes determined for chert blocks in northern California and Mexico. This result supports our model in which deep-water Franciscan-type cherts were deposited on the Farallon plate as it moved eastward beneath the equatorial productivity high, were accreted to the continental margin at low paleolatitudes, and were subsequently distributed northward by strike-slip faulting associated with movements of the Kula, Farallon, and Pacific plates. Upper Cretaceous turbidites of the Cachuma Formation were sampled at Agua Caliente Canyon to determine a constraining paleolatitude for accretion of the Jurassic chert sequences. These apparently unaltered rocks, however, were found to be completely overprinted by the A component of magnetization. Similar in situ directions and demagnetization behaviors observed in samples of other Upper Cretaceous turbidite sequences in southern and Baja California imply that these rocks might also give unreliable results.

Hydrogeology and trichloroethene contamination in the sea-level aquifer beneath the Logistics Center, Fort Lewis, Washington

USGS Publications Warehouse

Dinicola, Richard S.

2005-01-01

The U.S. Army disposed of waste trichloroethene (TCE) and other materials in the East Gate Disposal Yard near the Logistics Center on Fort Lewis, Washington, from the 1940s to the early 1970s. As a result, ground water contaminated with primarily TCE extends more than 3 miles downgradient from the East Gate Disposal Yard. The site is underlain by a complex and heterogeneous sequence of glacial and non-glacial deposits that have been broadly categorized into an upper and a lower aquifer (the latter referred to as the sea-level aquifer). TCE contamination was detected in both aquifers. This report describes an investigation by the U.S. Geological Survey (USGS) of the source, migration, and attenuation of TCE in the sea-level aquifer. A refined conceptual model for ground-water flow and contaminant migration into and through the sea-level aquifer was developed in large part from interpretation of environmental tracer data. The tracers used included stable isotopes of oxygen (18O), hydrogen (2H), and carbon (13C); the radioactive hydrogen isotope tritium (3H); common ions and redox-related analytes; chlorofluorocarbons; and sulfur hexafluoride. Tracer and TCE concentrations were determined for samples collected by the USGS from 37 wells and two surface-water sites in American Lake during 1999-2000. Ground-water levels were measured by the USGS in more than 40 wells during 2000-01, and were combined with measurements by the U.S. Army and others to create potentiometric-surface maps. Localized ground-water flow features were identified that are of particular relevance to the migration of TCE in the study area. A ridge of ground water beneath American Lake diverts the flow of TCE-contaminated ground water in the sea-level aquifer to the west around the southern end of the lake. Tracer data provided clear evidence that American Lake is a significant source of recharge to the sea-level aquifer that has created that ridge of ground water. High ground-water altitudes at locations north and northeast of the Logistics Center combined with the ridge beneath American Lake prevent TCE contaminated water beneath the Logistics Center from migrating toward municipal water-supply wells northeast of the site. The 1999-2000 TCE concentrations measured by the USGS at older wells screened in the sea-level aquifer were similar to those measured since 1995, but the known downgradient extent of the TCE contamination expanded nearly 2 miles after the Army installed and sampled new wells during 2003-04. Concentrations of TCE in the sea-level aquifer were consistently highest in the upper part of the aquifer throughout the plume, although TCE has spread throughout much of the thickness of the aquifer in the downgradient portions of the plume. Environmental tracer data indicated that the primary pathway for contaminant migration into the sea-level aquifer is through the previously identified confining unit window, an area where the predominately fine-grained confining unit is relatively coarse grained and more permeable. Other less substantial pathways for contaminant migration also were identified near the East Gate Disposal Yard and the I-5 pump-and-treat facilities. Those areas are near active pumping wells and ground-water reintroduction facilities, but there is no evidence that the contaminant migration was caused or enhanced by those activities. Within the sea-level aquifer, TCE concentrations continue to migrate westward in the flow field strongly influenced by ground-water recharge from American Lake. Historical data are not available to definitively determine if the 5-?g/L leading edge of the current TCE plume is stable or if it is still moving downgradient. However, an evaluation of the available data combined with TCE traveltime estimates indicates that the peak TCE concentrations in the sea-level aquifer may have not yet reached the wells near the currently defined leading edge of the plume. Hypothetically, the 5-?g/L leading edge

D.C. resistivity investigation to identify pathways for infiltration through playa lake in the High Plains of Texas

NASA Astrophysics Data System (ADS)

Abila, H.; Gurrola, H.; Fernandez, A.; Taylor, T. L.; Gonzalez, I.; Duron, Z. W.; Garza, J.; Ortega, J.

2017-12-01

Playa lakes an important resource for the recharge of the Ogallala aquifer but we do not fully understand how water passes through these features. This is in part because playas can be very different in their ability to retain water. To help develop a better understanding of these playa lakes the geophysics class at Texas Tech University conducted a geophysical investigation (including seismic and conductivity measurements as well as soil sampling) of a playa lake that is a short distance north of Lubbock, Texas. This playa lake is compartmentalized and appears to be two small playas in close proximity. The wester of the two playa retains water better than does the eastern playa. The primary goal is to find geophysical anomalies beneath playas to identify "the wet spots" that may shed light as to the pathways for infiltration. This abstract reports on the results of the dipole-dipole D.C.-resistivity component of the investigation. Resistivity was collected using several 9 volt batteries connected in series with a switch box and hand held multimeters to collect current and voltage data. Pseudosections produced before the rainy season began showed a conductive body the match the distribution of the clay rich floor of the Playa. We believe this clay rich player was about 1 to 1.5 meters thick based on sharp increase in the conductivity at that depth interval that was flat across the entire playa. Pseudosections produced from data collected after rain storms showed that this conductive layer increased in depth by up to 1 meter and there appears to be vertical conductive anomalies through the playa floor that may indicate infiltration pathways through the clay floor of the playa.

Complex Seismic Anisotropy at the Edges of a Very-low Velocity Province in the Lowermost Mantle

NASA Astrophysics Data System (ADS)

Wang, Y.; Wen, L.

2005-12-01

A prominent very-low velocity province (VLVP) in the lowermost mantle is revealed, and has been extensively mapped out in recent seismic studies (e.g., Wang and Wen, 2004). Seismic evidence unambiguously indicates that the VLVP is compositionally distinct, and its seismic structure can be best explained by partial melting driven by a compositional change produced in the early Earth's history (Wen, 2001; Wen et. al, 2001; Wang and Wen, 2004). In this presentation, we study the seismic anisotropic behavior inside the VLVP and its surrounding area using SKS and SKKS waveform data. We collect 272 deep earthquakes recorded by more than 80 stations in the Kaapvaal seismic array in southern Africa from 1997 to 1999. Based on the data quality, we choose SKS and SKKS waveform data for 16 earthquakes to measure the anisotropic parameters: the fast polarization direction and the splitting time, using the method of Silver and Chan (1991). A total of 162 high-quality measurements are obtained based on the statistics analysis of shear wave splitting results. The obtained anisotropy exhibits different patterns for the SKS and SKKS phases sampling inside the VLVP and at the edges of the VLVP. When the SKS and SKKS phases sample inside the VLVP, their fast polarization directions exhibit a pattern that strongly correlates with stations, gradually changing from 11°N~to 80°N~across the seismic array from south to north and rotating back to the North direction over short distances for several northernmost stations. The anisotropy pattern obtained from the analysis of the SKKS phases is the same as that from the SKS phases. However, when the SKS and SKKS phases sample at the edges of the VLVP, the measured anisotropy exhibits a very complex pattern. The obtained fast polarization directions change rapidly over a small distance, and they no longer correlate with stations; the measurements obtained from the SKS analysis also differ with those from the SKKS analysis. As the SKS and SKKS phases have similar propagation paths in the lithosphere beneath the array, but different sampling points near the core mantle boundary. The anisotropy in the lithosphere should have a similar influence on SKS and SKKS phases. Therefore, the similar anisotropy obtained from the SKS and SKKS phases sampling inside the VLVP and its correlation with seismic stations suggest that the observed anisotropy variation across the seismic array is mainly due to the anisotropy in the lithosphere beneath the Kaapvaal seismic array, and the interior of the VLVP is isotropic or weakly anisotropic. On the other hand, for the SKS and SKKS phases sampling at the edges of the VLVP, the observed complex anisotropy pattern and the lack of correlation between the results from the SKS and SKKS analyses indicate that part of that anisotropy has to originate from the lowermost mantle near the exit points of these phases at the core mantle boundary, revealing a complex flow pattern at the edges of the VLVP.

Composition of weathering crusts on sandstones from natural outcrops and architectonic elements in an urban environment.

PubMed

Marszałek, Mariola; Alexandrowicz, Zofia; Rzepa, Grzegorz

2014-12-01

This work presents mineralogical and chemical characteristics of weathering crusts developed on sandstones exposed to various air pollution conditions. The samples have been collected from sandstone tors in the Carpathian Foothill and from buildings in Kraków. It has been stated that these crusts differ in both fabric and composition. The sandstone black crust from tors is rich in organic matter and composed of amorphous silica. Sulphate incrustations accompanied by dust particles have been only sometimes observed. Beneath the black crust, a zone coloured by iron (oxyhydr)oxides occurs. The enrichment of the surface crust in silica and iron compounds protects the rock interior from atmospheric impact. The sandstones from architectonic details are also covered by a thin carbon-rich black crust, but they are visibly loosened. Numerous salts, mainly gypsum and halite, crystallise here, thus enhancing deterioration of the rock. Moreover, spherical particles originated from industrial emissions are much more common. Gypsum in natural outcrops, forms isolated and well-developed crystals, whilst these found on the architectonic details are finer and densely cover the surface. Such diversity reflects various concentrations of acid air pollutants in solutions.

Aeromagnetic maps with geologic interpretations for the Tularosa Valley, south-central New Mexico

USGS Publications Warehouse

Bath, G.D.

1977-01-01

An aeromagnetic survey of the Tularosa Valley in south-central New Mexico has provided information on the igneous rocks that are buried beneath alluvium and colluvium. The data, compiled as residual magnetic anomalies, are shown on twelve maps at a scale of 1:62,500. Measurements of magnetic properties of samples collected in the valley and adjacent highlands give a basis for identifying the anomaly-producing rocks. Precambrian rocks of the crystalline basement have weakly induced magnetizations and produce anomalies having low magnetic intensities and low magnetic gradients. Late Cretaceous and Cenozoic intrusive rocks have moderately to strongly induced magnetizations. Precambrian rocks produce prominent magnetic anomalies having higher amplitudes and higher gradients. The Quaternary basalt has a strong remanent magnetization of normal polarity and produces narrow anomalies having high-magnetic gradients. Interpretations include an increase in elevation to the top of buried Precambrian rock in the northern part of the valley, a large Late Cretaceous and Cenozoic intrusive near Alamogordo, and a southern extension of the intrusive rock exposed in the Jarilla Mountains. Evidence for the southern extension comes from a quantitative analysis of the magnetic anomalies..

Paleomagnetic investigation of late Quaternary sediments of south San Francisco Bay, California

USGS Publications Warehouse

Hillhouse, John W.

1977-01-01

Paleomagnetic inclinations of the Late Quaternary sediments of South San Francisco Bay were determined from bore hole samples collected near Dumbarton Bridge. The sediments consist of estuarine muds and nonmarine sand deposits, floored by bedrock of the Mesozoic Franciscan Formation. - Beneath Dumbarton Bridge the entire sedimentary fill is normally polarized; therefore, the fill postdates the Brunhes-Matayama polarity reversal (700,000 y. B.P.). Magnetic time lines such as the Mono Lake excursion (24,000 y. B.P.) and the reversed Blake event (110,000 y B.P.) were not found in this bore hole. In addition to Holocene and modern deposits of San Francisco Bay, an older estuarine unit occurs in the stratigraphic section. The older unit was deposited during a period of high sea level, tentatively correlated with the Sangamon interglacial period. Because evidence of the Blake event is not present in the older estuarine unit, the proposed age of this unit could not be confirmed. Although the Holocene estuarine deposits of South San Francisco Bay carry stable remanent magnetization, a reliable record of geomagnetic secular variation could not be recovered because the water-saturated sdiment was deformed by drilling.

H-Area Seepage Basins groundwater monitoring report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1993-03-01

During fourth quarter 1992, the groundwater at the H-Area Seepage Basins (HASB) was monitored in compliance with South Carolina Hazardous Waste Management Regulations, R61-79.265, Subpart F. Samples were collected from 130 wells that monitor the three separate hydrostratigraphic units that make up the uppermost aquifer beneath the HASB. A detailed description of the uppermost aquifer is included in the Resource Conservation and Recovery Act Part B Post-Closure Care Permit Application for the H-Area Hazardous Waste Management Facility submitted to the South Carolina Department of Health and Environmental Control in December 1990. Historically, as well as currently, tritium, nitrate, total alpha-emittingmore » radium, gross alpha, and mercury have been the primary constituents observed above final Primary Drinking Water Standards (PDWS) in groundwater at the HASB. Isoconcentration/isoactivity maps included in this report indicate both the concentration/activity and extent of the primary contaminants in each of the three hydrostratigraphic units during first and fourth quarter 1992. Water-level maps indicate that the groundwater flow rates and directions at the HASB have remained relatively constant since the basins ceased to be active in 1988.« less

H-Area Seepage Basins groundwater monitoring report. Fourth quarter 1992 and 1992 summary

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1993-03-01

During fourth quarter 1992, the groundwater at the H-Area Seepage Basins (HASB) was monitored in compliance with South Carolina Hazardous Waste Management Regulations, R61-79.265, Subpart F. Samples were collected from 130 wells that monitor the three separate hydrostratigraphic units that make up the uppermost aquifer beneath the HASB. A detailed description of the uppermost aquifer is included in the Resource Conservation and Recovery Act Part B Post-Closure Care Permit Application for the H-Area Hazardous Waste Management Facility submitted to the South Carolina Department of Health and Environmental Control in December 1990. Historically, as well as currently, tritium, nitrate, total alpha-emittingmore » radium, gross alpha, and mercury have been the primary constituents observed above final Primary Drinking Water Standards (PDWS) in groundwater at the HASB. Isoconcentration/isoactivity maps included in this report indicate both the concentration/activity and extent of the primary contaminants in each of the three hydrostratigraphic units during first and fourth quarter 1992. Water-level maps indicate that the groundwater flow rates and directions at the HASB have remained relatively constant since the basins ceased to be active in 1988.« less

Identifying and quantifying the stromal fibrosis in muscularis propria of colorectal carcinoma by multiphoton microscopy

NASA Astrophysics Data System (ADS)

Chen, Sijia; Yang, Yinghong; Jiang, Weizhong; Feng, Changyin; Chen, Zhifen; Zhuo, Shuangmu; Zhu, Xiaoqin; Guan, Guoxian; Chen, Jianxin

2014-10-01

The examination of stromal fibrosis within colorectal cancer is overlooked, not only because the routine pathological examinations seem to focus more on tumour staging and precise surgical margins, but also because of the lack of efficient diagnostic methods. Multiphoton microscopy (MPM) can be used to study the muscularis stroma of normal and colorectal carcinoma tissue at the molecular level. In this work, we attempt to show the feasibility of MPM for discerning the microstructure of the normal human rectal muscle layer and fibrosis colorectal carcinoma tissue practicably. Three types of muscularis propria stromal fibrosis beneath the colorectal cancer infiltration were first observed through the MPM imaging system by providing intercellular microstructural details in fresh, unstained tissue samples. Our approach also presents the capability of quantifying the extent of stromal fibrosis from both amount and orientation of collagen, which may further characterize the severity of fibrosis. By comparing with the pathology analysis, these results show that the MPM has potential advantages in becoming a histological tool for detecting the stromal fibrosis and collecting prognosis evidence, which may guide subsequent therapy procedures for patients into good prognosis.

Microbial extremophiles from the 2008 Schirmacher Oasis Expedition: preliminary results

NASA Astrophysics Data System (ADS)

Hoover, Richard B.; Pikuta, Elena V.; Townsend, Alisa; Anthony, Joshua; Guisler, Melissa; McDaniel, Jasmine; Bej, Asim; Storrie-Lombardi, Michael

2008-08-01

Among the most interesting targets for Astrobiology research are the polar ice caps and the permafrost of Mars and the ice and liquid water bodies that may lie beneath the frozen crusts of comets, the icy moons of Jupiter (Europa, Io and Ganymede) and Saturn (Titan and Enceladus). The permanently ice-covered lakes of Antarctica, such as Lake Vostok and Lake Untersee, provide some of the best terrestrial analogues for these targets. The 2008 International Tawani Schirmacher Oasis/Lake Untersee Expeditions have been organized to conduct studies of novel microbial extremophiles and investigate the biodiversity of the glaciers and ice-covered lakes of Dronning Maud Land, East Antarctica. This paper describes the preliminary analysis of the anaerobic microbial extremophiles isolated from samples collected during the 2008 International Schirmacher Oasis Antarctica Reconnaissance Expedition. These samples showed great diversity of psychrophlic and psychrotolerant bacteria. Six new anaerobic strains have been isolated in pure cultures and partially characterized. Two of them (strains ARHSd-7G and ARHSd-9G) were isolated from a small tidal pool near the colony of African Penguins Spheniscus demersus. Strain ARHSd-7G was isolated on mineral anaerobic medium with 3 % NaCl, pH 7 and D-glucose, it has motile, vibrion shape cells, and is Gram variable. Strain ARHSd-9G grew on anaerobic, alkaline medium with pH 9 and 1 % NaCl at 3°C. The substrate was D-glucose supplemented with yeast extract (0.05 %). Cells of strain ARHSd-9G had morphology of straight or slightly curved elongated rods and demonstrated unusual optical effects under dark-field visible light microscopy. The cells were spore-forming and Gram positive. From the mat sample collected near Lake Zub, the new strain LZ-3 was isolated in pure culture at 3°C. Strain LZ-3 was anaerobic and grew on 0.5 % NaCl mineral medium with Dglucose as a substrate. The gram positive cells were spore-forming. They exhibited a distinctive morphology of large rods with rounded ends and size 1x10 μm. From the sample of ice sculpted by wind and melting by solar heating, containing many entrained black rocks collected near Lake Podprudnoye the new strain ISLP-22 was isolated in pure culture. The cells of this strain had vibrion shape and were spore-forming and had "baseball bat" shapes). This culture preferred 0.1 % NaCl mineral anaerobic medium and grew rapidly at 3 °C. Currently, all strains are under physiological study and phylogenetic analysis.

Tracking Subpixel Targets with Critically Sampled Optical Sensors

DTIC Science & Technology

2012-09-01

5 [32]. The Viterbi algorithm is a dynamic programming method for calculating the MAP in O(tn2) time . The most common use of this algorithm is in the... method to detect subpixel point targets using the sensor’s PSF as an identifying characteristic. Using matched filtering theory, a measure is defined to...ocean surface beneath the cloud will have a different distribution. While the basic methods will adapt to changes in cloud cover over time , it is also

Groundwater conditions and studies in the Augusta–Richmond County area, Georgia, 2008–2009

USGS Publications Warehouse

Gonthier, Gerard; Lawrence, Stephen J.; Peck, Michael F.; Holloway, O. Gary

2011-01-01

Groundwater studies and monitoring efforts conducted during 2008–2009, as part of the U.S. Geological Survey (USGS) Cooperative Water Program with the City of Augusta in Richmond County, Georgia, provided data for the effective management of local water resources. During 2008–2009 the USGS completed: (1) installation of three monitoring wells and the collection of lithologic and geophysical logging data to determine the extent of hydrogeologic units, (2) collection of continuous groundwater-level data from wells near Well Fields 2 and 3, (3) collection of synoptic groundwater-level measurements and construction of potentiometric-surface maps in Richmond County to establish flow gradients and groundwater-flow directions in the Dublin and Midville aquifer systems, (4) completion of a 24-hour aquifer test to determine hydraulic characteristics of the lower Dublin aquifer, and upper and lower Midville aquifers in Well Field 2, and (5) collection of groundwater samples from selected wells in Well Field 2 for laboratory analysis of volatile organic compounds and groundwater tracers to assess groundwater quality and estimate the time of groundwater recharge. Potentiometric-surface maps of the Dublin and Midville aquifer systems for 2008–2009 indicate that the general groundwater flow direction within Richmond County is eastward toward the Savannah River, with the exception of the area around Well Field 2, where pumping interrupts the eastward flow of water toward the Savannah River and causes flow lines to bend toward the center of pumping. Results from a 24-hour aquifer test conducted in 2009 within the upper and lower Midville aquifers at Well Field 2 indicated a transmissivity and storativity for the upper and lower Midville aquifers, combined, of 4,000 feet-squared per day and 2x10-4, respectively. The upper and lower Midville aquifers and the middle lower Midville confining unit, which is 85-feet thick in this area, yielded horizontal hydraulic conductivity and specific storage values of about 45 feet per day and 2x10-6 ft-1, respectively. Results from the 24-hour aquifer test also indicate a low horizontal hydraulic conductivity for the lower Dublin aquifer of less than 1 foot per day. Of the 35 volatile organic compounds (VOCs) analyzed in 23 groundwater samples during 2008–2009, only six were detected above laboratory reporting limits in samples from eight wells. No concentration in groundwater samples collected during 2008–2009 exceeded drinking water standards. Trichloroethene had the maximum VOC concentration (1.9 micrograms per liter) collected from a water sample during 2008–2009. Water-quality sampling of several wells near Well Field 2 indicate that, while in operation, the northernmost production well might have diverted groundwater, containing low levels of trichloroethene from at least two other production wells. Analysis of sulfur hexafluoride data indicate the average year of recharge ranges between 1981 and 1984 for water samples from five wells open to the upper and lower Midville aquifers, and 1991 for a water sample from one shallow well open to the lower Dublin aquifer. All of these ages suggest a short flow path and nearby source of contamination. The actual source of low levels of VOCs at Well Field 2 remains unknown. Three newly installed monitoring wells indicate that hydrogeologic units beneath Well Fields 2 and 3 are composed of sand and clay layers. Hydrogeologic units, encountered at Well Field 2, in order of increasing depth are the lower Dublin confining unit, lower Dublin aquifer, upper Midville confining unit, upper Midville aquifer, lower Midville confining unit, and lower Midville aquifer. West of Well Field 3, hydrogeologic units, in order of increasing depth are the Upper Three Runs aquifer, Gordon confining unit, Gordon aquifer, lower Dublin confining unit, lower Dublin aquifer, upper Midville confining unit, upper Midville aquifer, lower Midville confining unit, and lower Midville aquifer.

Small-scale convection beneath the transverse ranges, California: Implications for interpretation of gravity anomalies

NASA Technical Reports Server (NTRS)

Humphreys, E. D.; Hager, B. H.

1985-01-01

Tomographic inversion of upper mantle P wave velocity heterogeneities beneath southern California shows two prominent features: an east-west trending curtain of high velocity material (up to 3% fast) in the upper 250 km beneath the Transverse Ranges and a region of low velocity material (up to 4% slow) in the 100 km beneath the Salton Trough. These seismic velocity anomalies were interpreted as due to small scale convection in the mantle. Using this hypothesis and assuming that temperature and density anomalies are linearly related to seismic velocity anomalies through standard coefficients of proportionality, leads to inferred variations of approx. + or - 300 C and approx. + or - 0.03 g/cc.

African hot spot volcanism: small-scale convection in the upper mantle beneath cratons.

PubMed

King, S D; Ritsema, J

2000-11-10

Numerical models demonstrate that small-scale convection develops in the upper mantle beneath the transition of thick cratonic lithosphere and thin oceanic lithosphere. These models explain the location and geochemical characteristics of intraplate volcanos on the African and South American plates. They also explain the presence of relatively high seismic shear wave velocities (cold downwellings) in the mantle transition zone beneath the western margin of African cratons and the eastern margin of South American cratons. Small-scale, edge-driven convection is an alternative to plumes for explaining intraplate African and South American hot spot volcanism, and small-scale convection is consistent with mantle downwellings beneath the African and South American lithosphere.

A geochemical study of lithospheric mantle beneath Northern Victoria Land (Antarctica): main evidences from volatile content in ultramafic xenoliths

NASA Astrophysics Data System (ADS)

Correale, Alessandra; Pelorosso, Beatrice; Rizzo, Andrea Luca; Coltorti, Massimo; Italiano, Francesco; Bonadiman, Costanza

2017-04-01

A geochemical study of ultramafic xenoliths from Northern Victoria Land (Green Point, GP and Handler Ridge, HR), is carried out in order to investigate the features of the lithosphere mantle beneath the Western Antarctic Ridge System (WARS). The majority of samples is spinel anhydrous lherzolite with rare presence of secondary phases (secondary cpx and glass). Geothermobarometric calculations, based on the Fe/Mg distribution among the peridotite minerals reveal that Sub Continental Lithospheric Mantle (SCLM) beneath Handler Ridge records temperatures and redox conditions higher then Greene Point (P fixed at 15 Kbar). Moreover, geochemical models evidence that, GP mantle domain represents a residuum after ˜7 to 21 % of partial melting in the spinel stability field, which was variably affected by interaction with infiltrating melts, acting in different times, from at least Jurassic to Cenozoic (Pelorosso et al., 2016). Fluid inclusions (FI) entrapped in olivine and pyroxene crystals were investigated for elemental and isotopic contents of both, noble gases (He, Ne, Ar) and CO2. He, Ar and Ne concentrations range from 1.52×10-14 to 1.07×10-12, from 4.09×10-13 to 3.47×10-11and from 2.84×10-16 to 7.57×10-14 mol/g, respectively, while the CO2amounts are between 7.08×10-10 and 8.12×10-7 mol/g. The 3He/4He varies between 5.95 and 20.18 Ra (where Ra is the 3He/4He ratio of air), being the lowest and the highest values measured in the He-poorer samples. Post-eruptive input of cosmogenic 3He and radiogenic 4He seems to influence mainly the samples associated to a lower He concentrations, increasing and decreasing respectively their primordial 3He/4He values, that for all the other samples range between 6.76 and 7.45 Ra. This range reasonably reflects the isotope signature of mantle beneath the investigated areas. The 4He/40Ar* ratio corrected for atmospheric-derived contamination ranges between 0.004 and 0.39. The lowest 4He/40Ar* values (4He/40Ar*<0.1) are systematically in correspondence of the He-poorer samples and probably derive by a selective loss of He with respect to Ar. The 4He/40Ar* values, ranging between 0.12 and 0.39 are lower than the typical mantle production ratio (4He/40Ar=1-5; Marty, 2012) and suggest that the pristine signature could have been modified by partial melting processes in agreement with major and trace element geochemistry of opx, cpx and sp. The carbon isotope composition of CO2 is reported as δ13C (where δ13C=[13C/12Csample - 13C/12Cstd]/13C/12Cstd×103) and varies between -2.5‰ and -4.5‰ with a more homogeneous value (at about -3.5) measured in the CO2-richest samples. This range of δ13C is compatible with typical mantle values (δ13C in average -5‰ Deines, 2002) and reasonably reflects the local mantle signature. References: Deines P., 2002. The carbon isotope geochemistry of mantle xenoliths. Earth-Science Reviews, 58, 247-278. Marty B. 2012. The origins and concentrations of water, carbon, nitrogen and noble gases on earth. Earth and Planetary Science Letters 313-314, 56-66. Pelorosso B., Bonadiman C., Coltorti M., Faccini B., Melchiorre M., Ntaflos T. & Gregoire M. 2016. Pervasive, tholeiitic refertilisation and heterogeneous metasomatism in Northern Victoria Land lithospheric mantle (Antarctica). Lithos, 248-251, 493-505.

The 1987 Whittier Narrows, California, earthquake: A Metropolitan shock

NASA Astrophysics Data System (ADS)

Hauksson, Egill; Stein, Ross S.

1989-07-01

Just 3 hours after the Whittier Narrows earthquake struck, it became clear that a heretofore unseen geological structure was seismically active beneath metropolitan Los Angeles. Contrary to initial expectations of strike-slip or oblique-slip motion on the Whittier fault, whose north end abuts the aftershock zone, the focal mechanism of the mainshock showed pure thrust faulting on a deep gently inclined surface [Hauksson et al., 1988]. This collection of nine research reports spans the spectrum of seismological, geodetic, and geological investigations carried out as a result of the Whittier Narrows earthquake. Although unseen, the structure was not unforeseen. Namson [1987] had published a retrodeformable geologic cross section (meaning that the sedimentary strata could be restored to their original depositional position) 100 km to the west of the future earthquake epicenter in which blind, or subsurface, thrust faults were interpreted to be active beneath the folded southern Transverse Ranges. Working 25 km to the west, Hauksson [1987] had also found a surprising number of microearthquakes with thrust focal mechanisms south of the Santa Monica mountains, another clue to a subsurface system of thrust faults. Finally, Davis [1987] had presented a preliminary cross section only 18 km to the west of Whittier Narrows that identified as "fault B" the thrust that would rupture later that year. Not only was the earthquake focus and its orientation compatible with the 10-15 km depth and north dipping orientation of Davis' proposed thrust, but fault B appears to continue beneath the northern flank of the Los Angeles basin, skirting within 5 km of downtown Los Angeles, an area of dense commercial high-rise building development. These results are refined and extended by Davis et al. [this issue].

Magmatic inflation at a dormant stratovolcano: 1996-1998 activity at Mount Peulik volcano, Alaska, revealed by satellite radar interferometry

USGS Publications Warehouse

Lu, Zhong; Wicks, Charles W.; Dzurisin, Daniel; Power, John A.; Moran, Seth C.; Thatcher, Wayne R.

2002-01-01

A series of ERS radar interferograms that collectively span the time interval from July 1992 to August 2000 reveal that a presumed magma body located 6.6 ??? 0.5 km beneath the southwest flank of the Mount Peulik volcano inflated 0.051 ??? 0.005 km3 between October 1996 and September 1998. Peulik has been active only twice during historical time, in 1814 and 1852, and the volcano was otherwise quiescent during the 1990s. The inflation episode spanned at least several months because separate interferograms show that the associated ground deformation was progressive. The average inflation rate of the magma body was ???0.003 km3/month from October 1996 to September 1997, peaked at 0.005 km3/month from 26 June to 9 October 1997, and dropped to ???0.001 km3/month from October 1997 to September 1998. An intense earthquake swarm, including three ML 4.8 - 5.2 events, began on 8 May 1998 near Becharof Lake, ???30 km northwest of Peulik. More than 400 earthquakes with a cumulative moment of 7.15 ?? 1017 N m were recorded in the area through 19 October 1998. Although the inflation and earthquake swarm occured at about the same time, the static stress changes that we calculated in the epicentral area due to inflation beneath Peulik appear too small to provide a causal link. The 1996-1998 inflation episode at Peulik confirms that satellite radar interferometry can be used to detect magma accumulation beneath dormant volcanoes at least several months before other signs of unrest are apparent. This application represents a first step toward understanding the eruption cycle at Peulik and other stratovolcanoes with characteristically long repose periods.

Constraints on seismic anisotropy beneath the Appalachian Mountains from Love-to-Rayleigh wave scattering

NASA Astrophysics Data System (ADS)

Servali, A.; Long, M. D.; Benoit, M.

2017-12-01

The eastern margin of North America has been affected by a series of mountain building and rifting events that have likely shaped the deep structure of the lithosphere. Observations of seismic anisotropy can provide insight into lithospheric deformation associated with these past tectonic events, as well as into present-day patterns of mantle flow beneath the passive margin. Previous work on SKS splitting beneath eastern North America has revealed fast splitting directions parallel to the strike of the Appalachian orogen in the central and southern Appalachians. A major challenge to the interpretation of SKS splitting measurements, however, is the lack of vertical resolution; isolating anisotropic structures at different depths is therefore difficult. Complementary constraints on the depth distribution of anisotropy can be provided by surface waves. In this study, we analyze the scattering of Love wave energy to Rayleigh waves, which is generated via sharp lateral gradients in anisotropic structure along the ray path. The scattered phases, known as quasi-Love (QL) waves, exhibit amplitude behavior that depend on the strength of the anisotropic contrast as well as the angle between the propagation azimuth and the anisotropic symmetry axis. We analyze data collected by the dense MAGIC seismic array across the central Appalachians. We examine teleseismic earthquakes of magnitude 6.7 and greater over a range of backazimuths, and isolate surface waves at periods between 100 and 500 seconds. We compare the data to synthetic seismograms generated by the Princeton Global ShakeMovie initiative to identify anomalous QL arrivals. We find evidence significant QL arrivals at MAGIC stations, with amplitudes depending on propagation azimuth and station location. Preliminary results are consistent with a sharp lateral gradient in seismic anisotropy across the Appalachian Mountains in the depth range between 100-200 km.

Faulting apparently related to the 1994 Northridge, California, earthquake and possible co-seismic origin of surface cracks in Potrero Canyon, Los Angeles County, California

USGS Publications Warehouse

Catchings, R.D.; Goldman, M.R.; Lee, W.H.K.; Rymer, M.J.; Ponti, D.J.

1998-01-01

Apparent southward-dipping, reverse-fault zones are imaged to depths of about 1.5 km beneath Potrero Canyon, Los Angeles County, California. Based on their orientation and projection to the surface, we suggest that the imaged fault zones are extensions of the Oak Ridge fault. Geologic mapping by others and correlations with seismicity studies suggest that the Oak Ridge fault is the causative fault of the 17 January 1994 Northridge earthquake (Northridge fault). Our seismically imaged faults may be among several faults that collectively comprise the Northridge thrust fault system. Unusually strong shaking in Potrero Canyon during the Northridge earthquake may have resulted from focusing of seismic energy or co-seismic movement along existing, related shallow-depth faults. The strong shaking produced ground-surface cracks and sand blows distributed along the length of the canyon. Seismic reflection and refraction images show that shallow-depth faults may underlie some of the observed surface cracks. The relationship between observed surface cracks and imaged faults indicates that some of the surface cracks may have developed from nontectonic alluvial movement, but others may be fault related. Immediately beneath the surface cracks, P-wave velocities are unusually low (<400 m/sec), and there are velocity anomalies consistent with a seismic reflection image of shallow faulting to depths of at least 100 m. On the basis of velocity data, we suggest that unconsolidated soils (<800 m/sec) extend to depths of about 15 to 20 m beneath our datum (<25 m below ground surface). The underlying rocks range in velocity from about 1000 to 5000 m/sec in the upper 100 m. This study illustrates the utility of high-resolution seismic imaging in assessing local and regional seismic hazards.

Anisotropic surface wave tomography in the Horn of Africa.

NASA Astrophysics Data System (ADS)

Sicilia, D.; Montagner, J. P.; Debayle, E.; Leveque, J. J.; Cara, M.; Lepine, J. C.; Beucler, E.; Sebai, A.

2003-04-01

One of the largest continental hotspot is located in the Afar Depression, in East of Africa. It has been advocated to be the surface expression of the South-West African Superswell, which is the antipode of the Pacific Superswell in the framework of the mantle degree 2 pattern. We performed an anisotropic surface wave tomography in the Horn of Africa in order to image the seismic structure beneath the region. Data were collected from the permanent IRIS and GEOSCOPE networks and from the PASSCAL experiment in Tanzania and Saudi Arabia. We supplemented our data base with a French deployment of 5 portable broadband stations surrounding the Afar Hotspot. Path average phase velocities are obtained using a method based on a least-squares minimization (Beucler et al., 2002). The data are corrected from the effect of the crust according to the a priori 3SMAC model (Nataf et Ricard, 1996). 3D-models of velocity, radial and azimuthal anisotropies are inverted for. We find low velocities beneath the Red Sea, the Gulf of Aden, the South East of the Tanzania Craton, the Hotspot and Central Africa. High velocities are present in the eastern Arabia and the Tanzania Craton. These results are in agreement with the anisotropic model of Debayle et al.(2002). The flow pattern can be derived from fast axis directions of seismic anisotropy. The anisotropy model beneath Afar displays a complex pattern, in which the hotspot seems to play a perturbating role. The azimuthal anisotropy shows that the Afar plume might be interpreted as feeding other hotspots in central Africa. The directions of fast axis are in good agreement with the results of previous SKS studies performed in the region (Gao et al., 1997; Wolfe et al., 1999; Barruol and Ismail, 2001).

Gravity and magnetic investigations of the Ghost Dance and Solitario Canyon faults, Yucca Mountain, Nevada

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ponce, D.A.; Langenheim, V.E.

1995-12-31

Ground magnetic and gravity data collected along traverses across the Ghost Dance and Solitario Canyon faults on the eastern and western flanks, respectively, of Yucca Mountain in southwest Nevada are interpreted. These data were collected as part of an effort to evaluate faulting in the vicinity of a potential nuclear waste repository at Yucca Mountain. Gravity and magnetic data and models along traverses across the Ghost Dance and Solitario Canyon faults show prominent anomalies associated with known faults and reveal a number of possible concealed faults beneath the eastern flank of Yucca Mountain. The central part of the eastern flankmore » of Yucca Mountain is characterized by several small amplitude anomalies that probably reflect small scale faulting.« less

Selected Natural Attenuation Monitoring Data, Operable Unit 1, Naval Undersea Warfare Center, Division Keyport, Washington, June 2005

USGS Publications Warehouse

Dinicola, Richard S.; Huffman, R.L.

2006-01-01

Previous investigations have shown that natural attenuation and biodegradation of chlorinated volatile organic compounds (VOCs) are substantial in shallow ground water beneath the 9-acre former landfill at Operable Unit 1 (OU-1), Naval Undersea Warfare Center, Division Keyport, Washington. The U.S. Geological Survey (USGS) has continued to monitor ground-water geochemistry to assure that conditions remain favorable for contaminant biodegradation. This report presents the ground-water geochemical and selected VOC data collected at OU-1 by the USGS during June 21-24, 2005, in support of long-term monitoring for natural attenuation. For June 2005, the strongly reducing conditions (sulfate reduction and methanogenesis) most favorable for reductive dechlorination of chlorinated VOCs were detected in fewer upper-aquifer wells than were detected during 2004. Redox conditions in ground water from the intermediate aquifer just downgradient of the landfill remained somewhat favorable for reductive dechlorination. Overall, the changes in redox conditions observed at individual wells have not been consistent or substantial throughout either the upper or the intermediate aquifers. In apparent contrast to changes in redox conditions, the chlorinated VOC concentrations were lower than previously measured in many of the piezometers in the northern phytoremediation plantation. The decrease in contaminant concentrations beneath the northern plantation and the end-product (ethane and ethene) evidence for reductive dechlorination are consistent with 2000-04 results. In the southern phytoremediation plantation, changes in chlorinated VOC concentrations were variable. Most notable was a substantial decrease in the sum of trichloroethene, cis-1,2-dichloroethene, and vinyl chloride concentrations at piezometer P1-9 from 75,000 to 1,000 micrograms per liter between 2004 and 2005. The high concentrations of the reductive dechlorination end-products ethane and ethene measured at the most contaminated sites (P1-6 and P1-7), as well as measurable concentrations at sites P1-9 and P1-10, are reliable evidence that reductive dechlorination of chlorinated VOCs is ongoing in the southern plantation. In the 10 passive-diffusion samplers deployed beneath the marsh stream, the highest chlorinated VOC concentrations measured were at a site (S-4) about midway along the sampled stream reach. In 2005, the sum of trichloroethene, cis-1,2-dichloroethene, and vinyl chloride concentrations increased nearly twofold in comparison to 2004. It is not certain that the apparent increase in concentrations is representative of site conditions. However, the chlorinated VOC concentrations have increased each time at the two most contaminated passive-diffusion sampler sites that have been sampled for multiple years. In the marsh stream, chlorinated VOC concentrations in surface water were low at the site (SW-S6) near the upgradient margin of the former landfill. Concentrations in the stream increased substantially after flowing past the southern phytoremediation plantation to the downstream site (MA-12). Overall, the 2005 data were consistent with previous findings of continued biodegradation of chlorinated VOCs in ground water, along with continued discharge of some chlorinated VOCs to surface water in the marsh stream.

Ancient Continental Lithosphere Dislocated Beneath Ocean Basins Along the Mid-Lithosphere Discontinuity: A Hypothesis

NASA Astrophysics Data System (ADS)

Wang, Zhensheng; Kusky, Timothy M.; Capitanio, Fabio A.

2017-09-01

The documented occurrence of ancient continental cratonic roots beneath several oceanic basins remains poorly explained by the plate tectonic paradigm. These roots are found beneath some ocean-continent boundaries, on the trailing sides of some continents, extending for hundreds of kilometers or farther into oceanic basins. We postulate that these cratonic roots were left behind during plate motion, by differential shearing along the seismically imaged mid-lithosphere discontinuity (MLD), and then emplaced beneath the ocean-continent boundary. Here we use numerical models of cratons with realistic crustal rheologies drifting at observed plate velocities to support the idea that the mid-lithosphere weak layer fostered the decoupling and offset of the African continent's buoyant cratonic root, which was left behind during Meso-Cenozoic continental drift and emplaced beneath the Atlantic Ocean. We show that in some cratonic areas, the MLD plays a similar role as the lithosphere-asthenosphere boundary for accommodating lateral plate tectonic displacements.

Nanoconfinement platform for nanostructure quantification via grazing-transmission X-ray scattering

DOEpatents

Black, Charles T.; Yager, Kevin G.

2017-01-31

A nano-confinement platform that may allow improved quantification of the structural order of nanometer-scale systems. Sample-holder `chips` are designed for the GTSAXS experimental geometry. The platform involves fabricated nanostructured sample holders on and in one or more corners of a substrate support where the sample material of interest is positioned at the corner of the substrate support. In an embodiment, the substrate material making up the substrate support beneath the sample-holding area is removed. A scattering x-ray sample platform includes a substrate support arranged in a parallelepiped form, having a substantially flat base and a substantially flat top surface, the top surface being substantially parallel with the base, the parallelepiped having a plurality of corners. At least one corner of the substrate support has a sample holding area formed in the top surface of the substrate support and within a predetermined distance from the corner. The sample holding area includes a regular array of nano-wells formed in the top surface of the substrate support.

Finite-frequency P-wave tomography of the Western Canada Sedimentary Basin: Implications for the lithospheric evolution in Western Laurentia

NASA Astrophysics Data System (ADS)

Chen, Yunfeng; Gu, Yu Jeffrey; Hung, Shu-Huei

2017-02-01

The lithosphere beneath the Western Canada Sedimentary Basin has potentially undergone Precambrian subduction and collisional orogenesis, resulting in a complex network of crustal domains. To improve the understanding of its evolutionary history, we combine data from the USArray and three regional networks to invert for P-wave velocities of the upper mantle using finite-frequency tomography. Our model reveals distinct, vertically continuous high (> 1%) velocity perturbations at depths above 200 km beneath the Precambrian Buffalo Head Terrane, Hearne craton and Medicine Hat Block, which sharply contrasts with those beneath the Canadian Rockies (<- 1%) at comparable depths. The P velocity increases from - 0.5% above 70 km depth to 1.5% at 330 km depth beneath southern Alberta, which provides compelling evidence for a deep, structurally complex Hearne craton. In comparison, the lithosphere is substantially thinner beneath the adjacent Buffalo Head Terrane (160 km) and Medicine Hat Block (200 km). These findings are consistent with earlier theories of tectonic assembly in this region, which featured distinct Archean and Proterozoic plate convergences between the Hearne craton and its neighboring domains. The highly variable, bimodally distributed craton thicknesses may also reflect different lithospheric destruction processes beneath the western margin of Laurentia.

Groundwater recharge in desert playas: current rates and future effects of climate change

NASA Astrophysics Data System (ADS)

McKenna, Owen P.; Sala, Osvaldo E.

2018-01-01

Our results from playas, which are topographic low areas situated in closed-catchments in drylands, indicated that projected climate change in Southwestern USA would have a net positive impact over runon and groundwater recharge beneath playas. Expected increased precipitation variability can cause up to a 300% increase in annual groundwater recharge beneath playas. This increase will overshadow the effect of decreased precipitation amount that could cause up to a 50% decrease in recharge beneath playas. These changes could have a significant impact on groundwater and carbon storage. These results are important given that groundwater resources in Southwestern USA continue to decline due to human consumption outpacing natural recharge of aquifers. Here, we report on groundwater recharge rates ranging from less than 1 mm to greater than 25 mm per year beneath desert playas. Playas located in larger and steeper catchments with finer-textured soils had the highest rates of recharge. Vegetation cover had no effect on recharge beneath playas. We modeled catchment runoff generation and found that the amount of runon a playa receives annually strongly correlated to the rate of groundwater recharge beneath that playa. Runon occurred during precipitation events larger than 20 mm and increased linearly with events above that threshold.

Geometry of slab, intraslab stress field and its tectonic implication in the Nankai trough, Japan

NASA Astrophysics Data System (ADS)

Xu, J.; Kono, Y.

2002-07-01

The characteristics of geometry of slabs and the intraslab stress field in the Nankai subduction zone, Japan, were analyzed based on highly accurate hypocentral data and focal mechanism solutions. The results suggest that the shallow seismic zone of the Philippine Sea slab subducts with dip angels between 10 and 22 degrees beneath Shikoku and the Kii peninsula, and between 11 and 40 degrees beneath Kyushu. Two types of seismogenic stress field exist within the slab. The stress field of down-dip compression type can be seen in the slab beneath Shikoku and the Kii peninsula, where the horizontal component of regional compression stress is NNW. On the other hand the stress field of down-dip extension type within the slab is dominant in the region from western Shikoku to Kyushu, where the direction of horizontal compressive stress is near WWN. The existence of the two types of stress field is related to the differences of slab geometry and slab age of the subduciton zone. These properties imply that slab beneath Kyushu (40 Ma) probably is older than that beneath Shikoku and the Kii peninsula (11-20 Ma). The young slab of the oceanic Philippine Sea plate subducts with a shallow angle beneath the Eurasian plate in Shikoku and the Kii peninsula. The subduction has encountered strong resistance there, resulting in a down-dip compression stress field. The down-dip extension stress field may be related to the older slab of the Philippine Sea plate which subducts beneath Kyushu with a steeper dip angle.

Crustal structure beneath the Kenya Rift from axial profile data

USGS Publications Warehouse

Mechie, J.; Keller, Gordon R.; Prodehl, C.; Gaciri, S.; Braile, L.W.; Mooney, W.D.; Gajewski, D.; Sandmeier, K.-J.

1994-01-01

Modelling of the KRISP 90 axial line data shows that major crustal thinning occurs along the axis of the Kenya Rift from Moho depths of 35 km in the south beneath the Kenya Dome in the vicinity of Lake Naivasha to 20 km in the north beneath Lake Turkana. Low Pn velocities of 7.5-7.7 km/s are found beneath the whole of the axial line. The results indicate that crustal extension increases to the north and that the low Pn velocities are probably caused by magma (partial melt) rising from below and being trapped in the uppermost kilometres of the mantle. Along the axial line, the rift infill consisting of volcanics and a minor amount of sediments varies in thickness from zero where Precambrian crystalline basement highs occur to 5-6 km beneath the lakes Turkana and Naivasha. Analysis of the Pg phase shows that the upper crystalline crust has velocities of 6.1-6.3 km/s. Bearing in mind the Cainozoic volcanism associated with the rift, these velocities most probably represent Precambrian basement intruded by small amounts of igneous material. The boundary between the upper and lower crusts occurs at about 10 km depth beneath the northern part of the rift and 15 km depth beneath the southern part of the rift. The upper part of the lower crust has velocities of 6.4-6.5 km/s. The basal crustal layer which varies in thickness from a maximum of 2 km in the north to around 9 km in the south has a velocity of about 6.8 km/s. ?? 1994.

Crustal and mantle shear velocity structure of Costa Rica and Nicaragua from ambient noise and teleseismic Rayleigh wave tomography

NASA Astrophysics Data System (ADS)

Harmon, Nicholas; de la Cruz, Mariela Salas; Rychert, Catherine Ann; Abers, Geoffrey; Fischer, Karen

2013-11-01

The Costa Rica-Nicaragua subduction zone shows systematic along strike variation in arc chemistry, geology, tectonics and seismic velocity and attenuation, presenting global extremes within a few hundred kilometres. In this study, we use teleseismic and ambient noise derived surface wave tomography to produce a 3-D shear velocity model of the region. We use the 48 stations of the TUCAN array, and up to 94 events for the teleseismic Rayleigh wave inversion, and 18 months of continuous data for cross correlation to estimate Green's functions from ambient noise. In the shallow crust (0-15 km) we observe low-shear velocities directly beneath the arc volcanoes (<3 km s-1) and higher velocities in the backarc of Nicaragua. The anomalies below the volcanoes are likely caused by heated crust, intruded by magma. We estimate crustal thickness by picking the depth to the 4 km s-1 velocity contour. We infer >40-km-thick crust beneath the Costa Rican arc and the Nicaraguan Highlands, thinned crust (˜20 km) beneath the Nicaraguan Depression, and increasing crustal thickness in the backarc region, consistent with receiver function studies. The region of thinned, seismically slow and likely weakened crust beneath the arc in Nicaragua is not localizing deformation associated with oblique subduction. At mantle depths (55-120 km depth) we observe lower shear velocities (up to 3 per cent) beneath the Nicaraguan arc and backarc than beneath Costa Rica. Our low-shear velocity anomaly beneath Nicaragua is in the same location as a low-shear velocity anomaly and displaced towards the backarc from the high VP/VS anomaly observed in body wave tomography. The lower shear velocity beneath Nicaragua may indicate higher melt content in the mantle perhaps due to higher volatile flux from the slab or higher temperature. Finally, we observe a linear high-velocity region at depths >120 km parallel to the trench, which is consistent with the subducting slab.

Evaluation of imidacloprid-treated traps as an attract and kill system for filth flies during contingency operations.

PubMed

Dunford, James C; Hoel, David F; Hertz, Jeffrey C; England, David B; Dunford, Kelly R; Stoops, Craig A; Szumlas, Daniel E; Hogsette, Jerome A

2013-01-01

Two field trials were conducted to evaluate if filth fly trap efficacy was increased by augmentation with an insecticide application to the trap's exterior. Four Fly Terminator Pro traps (Farnam Companies, Inc, Phoenix, AZ) baited with Terminator Fly Attractant (in water) were suspended on polyvinyl chloride pipe framing at a municipal waste transfer site in Clay County, Florida. The outer surfaces of 2 traps were treated with Maxforce Fly Spot Bait (Bayer Environmental Science, Research Triangle Park, NC) (10% imidacloprid) to compare kill rates between treated and untreated traps. Kill consisted of total flies collected from inside traps and from mesh nets suspended beneath all traps, both treated and untreated. Each of 2 treated and untreated traps was rotated through 4 trap sites every 24 hrs. In order to evaluate operational utility and conservation of supplies during remote contingency operations, fly attractant remained in traps for the duration of the first trial but was changed daily during the second trial (following manufacturer's recommendations). In addition, ½ strength Terminator Fly Attractant was used during the first trial and traps were set at full strength during the second trial. Flies collected within the traps and in mesh netting were counted and identified. Three species, Musca domestica (L.), Chrysomya megacephala (F.), and Lucilia cuprina (Wiedemann), comprised the majority of samples in both trials. The net samples recovered more flies when the outer surface was treated with imidacloprid, however, treated traps collected fewer flies inside the trap than did untreated traps for both trials. No significant statistical advantage was found in treating Fly Terminator Pro trap exteriors with Maxforce Fly Spot Bait. However, reducing manufacturer's recommended strength of Terminator Fly Attractant showed similar results to traps set at full strength. Treating the outer surfaces may improve kill of fly species that do not enter the trap. Terminator Fly Attractant was also found to be more effective if traps were not changed daily and left to hold dead flies for longer periods.

Detrital Zircon U-Pb and Hf-isotope Constrains on Basement Ages, Granitic Magmatism, and Sediment Provenance in the Malay Peninsula

NASA Astrophysics Data System (ADS)

Sevastjanova, Inga; Clements, Benjamin; Hall, Robert; Belousova, Elena; Pearson, Norman; Griffin, William

2010-05-01

The Malay Peninsula forms the western part of central Sundaland in SE Asia. Sundaland comprises Indochina, the Thai-Malay Peninsula, Sumatra, Java, Borneo, and the shallow shelf between these landmasses. It is a composite region of continental crustal fragments that are separated by sutures that represent remnant ocean basins and volcanic arcs. The Malay Peninsula includes two of these fragments - East Malaya and Sibumasu - separated by the Bentong-Raub Suture Zone. The latter is a Palaeo-Tethyan ocean remnant. Granitoids of the Malay Peninsula are the major sources of detrital zircon in Sundaland. East Malaya is intruded by Permian-Triassic Eastern Province granitoids interpreted as products of Palaeozoic subduction of oceanic crust beneath the East Malaya Volcanic Arc. Sibumasu is intruded by Triassic Main Range Province granitoids interpreted as syn- to post-collisional magmatism following suturing to East Malaya. Locally, there are minor Late Cretaceous plutons. Basements of Sibumasu and East Malaya are not exposed and their ages are poorly constrained. The exact timing of the collision between these fragments is also contentious. In order to resolve these uncertainties, 752 U-Pb analyses from 9 samples were carried out on detrital zircons from modern rivers draining the Malay Peninsula and, of these, 243 grains from 6 samples were selected for Hf-isotope analyses. U-Pb zircon ages show that small numbers of Neoarchean-Proterozoic grains are consistently present in all samples, but do not form prominent populations. Permian-Triassic populations are dominant. Only one sample contains a small Jurassic population probably sourced from the area of Thailand and most likely recycled from fluvial-alluvial Mesozoic 'red-beds'. Late Cretaceous populations are locally abundant. Hf-isotope crustal model ages suggest that basement beneath the Malay Peninsula is heterogeneous. Some basement may be Neoarchean but there is no evidence for basement older than 2.8 Ga beneath the Malay Peninsula. Both Sibumasu and East Malaya basements are Paleoproterozoic, but of different ages. 176Hf/177Hfi ratios suggest that Permian-Triassic zircons were sourced from three major magmatic suites: (a) Permian crust-derived granitoids, (b) Early-Middle Triassic granitoids with a mixed mantle- and crust-derived source, and (c) Late Triassic crust-derived granitoids. This suggests three major Permian-Triassic episodes of magmatism in the Malay Peninsula. Two of these episodes (a and b) occurred in the Eastern Province. This suggests a multi-phase evolution of the East Malaya Volcanic Arc. Crust-derived zircon Hf-isotope signatures are unusual for a continental margin arc and may indicate contamination from older crust beneath the East Malaya fragment. A Late Permian-Early Triassic gap in magmatism and subsequent change of zircon source may indicate a micro-collision around 260-270 Ma (e.g. with an island arc or a seamount on the Paleo-Tethys oceanic crust). U-Pb ages and Hf-isotope composition of zircons sourced from the Main Range Province granitoids suggest that Sibumasu-East Malaya collision occurred by Late Triassic, but it is not clear when exactly this collision initiated. Different Hf-isotope signatures of Triassic zircons can be used as indicators of sediment provenance from the Malay Peninsula. Crust-derived signatures are diagnostic of Triassic zircons from the Main Range Province source, whereas mixed crust- and mantle-derived signatures of similar age zircons indicate Eastern Province source.

Pathway from subducting slab to surface for melt and fluids beneath Mount Rainier.

PubMed

McGary, R Shane; Evans, Rob L; Wannamaker, Philip E; Elsenbeck, Jimmy; Rondenay, Stéphane

2014-07-17

Convergent margin volcanism originates with partial melting, primarily of the upper mantle, into which the subducting slab descends. Melting of this material can occur in one of two ways. The flow induced in the mantle by the slab can result in upwelling and melting through adiabatic decompression. Alternatively, fluids released from the descending slab through dehydration reactions can migrate into the hot mantle wedge, inducing melting by lowering the solidus temperature. The two mechanisms are not mutually exclusive. In either case, the buoyant melts make their way towards the surface to reside in the crust or to be extruded as lava. Here we use magnetotelluric data collected across the central state of Washington, USA, to image the complete pathway for the fluid-melt phase. By incorporating constraints from a collocated seismic study into the magnetotelluric inversion process, we obtain superior constraints on the fluids and melt in a subduction setting. Specifically, we are able to identify and connect fluid release at or near the top of the slab, migration of fluids into the overlying mantle wedge, melting in the wedge, and transport of the melt/fluid phase to a reservoir in the crust beneath Mt Rainier.

Pathway from subducting slab to surface for melt and fluids beneath Mount Rainier

NASA Astrophysics Data System (ADS)

McGary, R. Shane; Evans, Rob L.; Wannamaker, Philip E.; Elsenbeck, Jimmy; Rondenay, Stéphane

2014-07-01

Convergent margin volcanism originates with partial melting, primarily of the upper mantle, into which the subducting slab descends. Melting of this material can occur in one of two ways. The flow induced in the mantle by the slab can result in upwelling and melting through adiabatic decompression. Alternatively, fluids released from the descending slab through dehydration reactions can migrate into the hot mantle wedge, inducing melting by lowering the solidus temperature. The two mechanisms are not mutually exclusive. In either case, the buoyant melts make their way towards the surface to reside in the crust or to be extruded as lava. Here we use magnetotelluric data collected across the central state of Washington, USA, to image the complete pathway for the fluid-melt phase. By incorporating constraints from a collocated seismic study into the magnetotelluric inversion process, we obtain superior constraints on the fluids and melt in a subduction setting. Specifically, we are able to identify and connect fluid release at or near the top of the slab, migration of fluids into the overlying mantle wedge, melting in the wedge, and transport of the melt/fluid phase to a reservoir in the crust beneath Mt Rainier.

Crustal tomography of the 2016 Kumamoto earthquake area in West Japan using P and PmP data

NASA Astrophysics Data System (ADS)

Wang, Haibo; Zhao, Dapeng; Huang, Zhouchuan; Xu, Mingjie; Wang, Liangshu; Nishizono, Yukihisa; Inakura, Hirohito

2018-05-01

A high-resolution model of three-dimensional (3-D) P-wave velocity (Vp) tomography of the crust in the source area of the 2016 Kumamoto earthquake (M 7.3) in West Japan is determined using a large number of arrival times of first P-waves and reflected P-waves from the Moho discontinuity (PmP). The PmP data are collected from original seismograms of the Kumamoto aftershocks and other local crustal events in Kyushu. Detailed resolution tests show that the addition of the PmP data can significantly improve the resolution of the crustal tomography, especially that of the lower crust. Our results show that significant low-velocity (low-V) anomalies exist in the entire crust beneath the active arc volcanoes, which may reflect the pathway of arc magmas. The 2016 Kumamoto earthquake occurred at the edge of a small low-V zone in the upper crust. A significant low-V anomaly is revealed in the lower crust beneath the source zone, which may reflect the arc magma and fluids ascending from the mantle wedge. These results suggest that the rupture nucleation of the 2016 Kumamoto earthquake was affected by fluids and arc magma.

Evaluation of Confining Layer Integrity Beneath the South District Wastewater Treatment Plant, Miami-Dade Water and Sewer Department, Dade County, Florida

DOE Office of Scientific and Technical Information (OSTI.GOV)

Starr, R.C.; Green, T.S.; Hull, L.C.

2001-02-28

A review has been performed of existing information that describes geology, hydrogeology, and geochemistry at the South District Wastewater Treatment Plant, which is operated by the Miami-Dade Water and Sewer Department, in Dade County, Florida. Treated sanitary wastewater is injected into a saline aquifer beneath the plant. Detection of contaminants commonly associated with treated sanitary wastewater in the freshwater aquifer that overlies the saline aquifer has indicated a need for a reevaluation of the ability of the confining layer above the saline aquifer to prevent fluid migration into the overlying freshwater aquifer. Review of the available data shows that themore » geologic data set is not sufficient to demonstrate that a competent confining layer is present between the saline and freshwater aquifers. The hydrogeologic data also do not indicate that a competent confining layer is present. The geochemical data show that the freshwater aquifer is contaminated with treated wastewater, and the spatial patterns of contamination are consistent with upward migration through localized conduits through the Middle Confining Unit, such as leaking wells or natural features. Recommendations for collection and interpretation of additional site characterization data are provided.« less

Evaluation of Confining Layer Integrity Beneath the South District Wastewater Treatment Plant, Miami-Dade Water and Sewer Department, Dade County, Florida

DOE Office of Scientific and Technical Information (OSTI.GOV)

Starr, Robert Charles; Green, Timothy Scott; Hull, Laurence Charles

2001-02-01

A review has been performed of existing information that describes geology, hydrogeology, and geochemistry at the South District Wastewater Treatment Plant, which is operated by the Miami-Dade Water and Sewer Department, in Dade County, Florida. Treated sanitary wastewater is injected into a saline aquifer beneath the plant. Detection of contaminants commonly associated with treated sanitary wastewater in the freshwater aquifer that overlies the saline aquifer has indicated a need for a reevaluation of the ability of the confining layer above the saline aquifer to prevent fluid migration into the overlying freshwater aquifer. Review of the available data shows that themore » geologic data set is not sufficient to demonstrate that a competent confining layer is present between the saline and freshwater aquifers. The hydrogeologic data also do not indicate that a competent confining layer is present. The geochemical data show that the freshwater aquifer is contaminated with treated wastewater, and the spatial patterns of contamination are consistent with upward migration through localized conduits through the Middle Confining Unit, such as leaking wells or natural features. Recommendations for collection and interpretation of additional site characterization data are provided.« less

Evidencing a prominent Moho topography beneath the Iberian-Western Mediterranean Region, compiled from controlled-source and natural seismic surveys

NASA Astrophysics Data System (ADS)

Diaz, Jordi; Gallart, Josep; Carbonell, Ramon

2016-04-01

The complex tectonic interaction processes between the European and African plates at the Western Mediterranean since Mesozoic times have left marked imprints in the present-day crustal architecture of this area, particularly as regarding the lateral variations in crustal and lithospheric thicknesses. The detailed mapping of such variations is essential to understand the regional geodynamics, as it provides major constraints for different seismological, geophysical and geodynamic modeling methods both at lithospheric and asthenospheric scales. Since the 1970s, the lithospheric structure beneath the Iberian Peninsula and its continental margins has been extensively investigated using deep multichannel seismic reflection and refraction/wide-angle reflection profiling experiments. Diaz and Gallart (2009) presented a compilation of the results then available beneath the Iberian Peninsula. In order to improve the picture of the whole region, we have now extended the geographical area to include northern Morocco and surrounding waters. We have also included in the compilation the results arising from all the seismic surveys performed in the area and documented in the last few years. The availability of broad-band sensors and data-loggers equipped with large storage capabilities has allowed in the last decade to boost the investigations on crustal and lithospheric structure using natural seismicity, providing a spatial resolution never achieved before. The TopoIberia-Iberarray network, deployed over Iberia and northern Morocco, has provided a good example of those new generation seismic experiments. The data base holds ~300 sites, including the permanent networks in the area and hence forming a unique seismic database in Europe. In this contribution, we retrieve the results on crustal thickness presented by Mancilla and Diaz (2015) using data from the TopoIberia and associated experiments and we complement them with additional estimations beneath the Rif Cordillera arising from more recent deployments. We have now included also the sparse results in the region previously published, with the aim of checking the consistency of the results, hence giving more strength to the retained features. Combining the Moho depth values coming from controlled source and natural seismicity experiments has finally allowed us to build up a high quality grid of the region at crustal scale, which is completed in the non-sampled areas by the wide-scale CRUST1.0 model. The final picture evidences the geodynamic diversity of the area, including crustal imbrication in the Pyrenean range, a large and relatively undisturbed Variscan Massif in the center of Iberia and a probable delamination process beneath the Gibraltar Arc. Crustal thicknesses range from values around 15 km in continental margins (Cantabrian margin and Valencia Trough) to depths exceeding 50 km beneath the Pyrenees and the Rif Cordillera. A new 3D model of those variations is presented here to illustrate and summarize such large variations

Crustal Thickness and Magnetization beneath Crisium and Moscoviense Lunar Impact Basins

NASA Astrophysics Data System (ADS)

Quesnel, Y.

2016-12-01

The recent NASA GRAIL mission allowed to derive a high-resolution model of the Moon's crustal thickness. It revealed that the Mare Crisium and Moscoviense large impact basins have the thinnest (< 7-8 km) crust of the Moon. On the other hand, significative magnetic field anomalies were measured over these basins by Lunar Prospector and Kaguya magnetometers. The Crisium lunar impact basin shows two localized intense ( 10 nT at 30 km of altitude) magnetic field anomalies located nearby its North and South borders, while Moscoviense shows a relatively-intense ( 4-5 nT at 30 km) central magnetic field anomaly. In details, these two anomalies are exactly located where the thinnest (<1-3 km) crust within the basins is predicted by the crustal thickness models. In this study we investigate this apparent anti-correlation by modeling the sources of these potential field data using several forward approaches in 2D and 3D. The parameters of the crustal source models are constrained by density and magnetization measurements on APOLLO samples, and by standard values for the lunar mantle and crust. Several possible models will be shown for the two basins. Preliminary results suggest that, beneath the thin Mare basalt layer seen at the floor of both basins, a magnetized layer with laterally-varying thickness is required. This layer may correspond to an impact melt sheet. We here exclude the hypothesis that a part of the lunar upper mantle could be magnetized beneath these basins (perhaps due to post-impact processes?), largely reducing the range of possible depths for the magnetic sources.

Silt and gas accumulation beneath an artificial recharge spreading basin, Southwestern Utah, U.S.A.

USGS Publications Warehouse

Heilweil, V.M.; Solomon, D.K.; Ortiz, G.

2009-01-01

Sand Hollow Reservoir in southwestern Utah, USA, is operated for both surface-water storage and artificial recharge to the underlying Navajo Sandstone. The total volume of estimated artificial recharge between 2002 and 2007 is 85 million cubic meters (69,000 acre-feet). Since 2002, artificial recharge rates have generally been declining and are inversely correlated with the increasing surface area of the reservoir. Permeability testing of core samples retrieved from beneath the reservoir indicates that this decline may not be due to silt accumulation. Artificial recharge rates also show much seasonal variability. Calculations of apparent intrinsic permeability show that these variations can only partly be explained by variation in water viscosity associated with seasonal changes in water temperature. Sporadic seasonal trends in recharge rates and intrinsic permeability during 2002-2004 could be associated with the large fluctuations in reservoir elevation and wetted area. From 2005 through 2007, the reservoir was mostly full and there has been a more consistent seasonal pattern of minimum recharge rates during the summer and maximum rates during the autumn. Total dissolved-gas pressure measurements indicate the presence of biogenic gas bubbles in the shallow sediments beneath the shallower parts of Sand Hollow Reservoir when the water is warmer. Permeability reduction associated with this gas clogging may contribute to the decrease in artificial recharge rates during the spring and summer, with a subsequently increasing recharge rates in the autumn associated with a decline in volume of gas bubbles. Other possible causes for seasonal variation in artificial recharge rates require further investigation.

Helium and carbon gas geochemistry of pore fluids from the sediment-rich hydrothermal system in Escanaba Trough

USGS Publications Warehouse

Ishibashi, J.-I.; Sato, M.; Sano, Y.; Wakita, H.; Gamo, T.; Shanks, Wayne C.

2002-01-01

Ocean Drilling Program (ODP) Leg 169, which was conducted in 1996 provided an opportunity to study the gas geochemistry in the deeper part of the sediment-rich hydrothermal system in Escanaba Trough. Gas void samples obtained from the core liner were analyzed and their results were compared with analytical data of vent fluid samples collected by a submersible dive program in 1988. The gas geochemistry of the pore fluids consisted mostly of a hydrothermal component and was basically the same as that of the vent fluids. The He isotope ratios (R/RA = 5.6-6.6) indicated a significant mantle He contribution and the C isotopic compositions of the hydrocarbons [??13C(CH4) = -43???, ??13C(C2H6) = -20???] were characterized as a thermogenic origin caused by hydrothermal activity. On the other hand, the pore fluids in sedimentary layers away from the hydrothermal fields showed profiles which reflected lateral migration of the hydrothermal hydrocarbons and abundant biogenic CH4. Helium and C isotope systematics were shown to represent a hydrothermal component and useful as indicators for their distribution beneath the seafloor. Similarities in He and hydrocarbon signatures to that of the Escanaba Trough hydrothermal system were found in some terrestrial natural gases, which suggested that seafloor hydrothermal activity in sediment-rich environments would be one of the possible petroleum hydrocarbon generation scenarios in unconventional geological settings. ?? 2002 Elsevier Science Ltd. All rights reserved.

Description and hydrogeologic evaluation of nine hazardous-waste sites in Kansas, 1984-86

USGS Publications Warehouse

Hart, R.J.; Spruill, T.B.

1988-01-01

Wastes generated at nine hazardous-waste sites in Kansas were disposed in open pits, 55-gal drums, or large storage tanks. These disposal methods have the potential to contaminate groundwater beneath the sites, the soil on the sites, and nearby surface water bodies. Various activities on the nine sites included production of diborane, transformer oil waste, production of soda ash, use of solvents for the manufacture of farm implements, reclamation of solvents and paints, oil-refinery wastes, meat packaging, and the manufacture and cleaning of tanker-truck tanks. Monitoring wells were installed upgradient and downgradient from the potential contamination source on each site. Strict decontamination procedures were followed to prevent cross contamination between well installations. Air-quality surveys were made on each site before other investigative procedures started. Hydrogeologic investigative techniques, such as terrain geophysical surveys, gamma-ray logs, and laboratory permeameter tests, were used. Groundwater level measurements provide data to determine the direction of flow. Groundwater contamination detected under the sites posed the greatest threat to the environment because of possible migration of contaminants by groundwater flow. Concentrations of volatile organic compounds, polynuclear aromatic hydrocarbons, and trace metals were detected in the groundwater at several of the sites. Many of the same compounds detected in the groundwater also were detected in soil and bed-material samples collected onsite or adjacent to the sites. Several contaminants were detected in background samples of groundwater and soil. (USGS)

Geology and geothermal potential of the tecuamburro volcano area, Guatemala

USGS Publications Warehouse

Duffield, W.A.; Heiken, G.H.; Wohletz, K.H.; Maassen, L.W.; Dengo, G.; McKee, E.H.; Castaneda, O.

1992-01-01

Tecuamburro, an andesitic stratovolcano in southeastern Guatemala, is within the chain of active volcanoes of Central America. Though Tecuamburro has no record of historic eruptions, radiocarbon ages indicate that eruption of this and three other adjacent volcanoes occurred within the past 38,300 years. The youngest eruption produced a dacite dome. Moreover, powerful steam explosions formed a 250 m wide crater about 2900 years ago near the base of this dome. The phreatic crater contains a pH-3 thermal lake. Fumaroles are common along the lake shore, and several other fumaroles are located nearby. Neutral-chloride hot springs are at lower elevations a few kilometers away. All thermal manifestations are within an area of about 400 km2 roughly centered on Tecuamburro Volcano. Thermal implications of the volume, age, and composition of the post-38.3 ka volcanic rocks suggest that magma, or recently solidified hot plutons, or both are in the crust beneath these lavas. Chemical geothermometry carried out by other workers suggests that a hydrothermal-convection system is centered over this crustal heat source. Maximum temperatures of about 300??C are calculated for samples collected in the area of youngest volcanism, whereas samples from outlying thermal manifestations yield calculated temperatures <- 165??C. An 808 m deep drill hole completed in 1990 to partly test the geothermal model developed from surface studies attained a maximum temperature of almost 240??C. Thus, the possibility of a commercial-grade hydrothermal resource in the area seems high. ?? 1992.

Crustal Rock: Recorder of Oblique Impactor Meteoroid Trajectories

NASA Astrophysics Data System (ADS)

Ahrens, Thomas J.

2005-07-01

Oblique impact experiments in which 2g lead bullets strike samples of San Marcos granite and Bedford limestone at 1.2 km/s induce zones of increased crack density (termed shocked damage) which result in local decreases in bulk and shear moduli that results in maximum decreases of 30-40% in compressional and shear wave velocity (Budianski and O'Connell). Initial computer simulation of oblique impacts of meteorites (Pierazzo and Melosh) demonstrate the congruence of peak shock stress trajectory with the pre-impact meteoroid trajectory. We measure (Ai and Ahrens) via multi-beam (˜ 300) tomographic inversion, the sub-impact surface distribution of damage from the decreases in compressional wave velocity in the 20 x 20 x 15 cm rock target. The damage profiles for oblique impacts are markedly asymmetric (in plane of pre-impact meteoroid pre-impact trajectory) beneath the nearly round excavated craters. Thus, meteorite trajectory information can be recorded in planetary surfaces. Asymmetric sub-surface seismic velocity profiles beneath the Manson (Iowa) and Ries (Germany) impact craters demonstrate that pre-impact meteoroid trajectories records remain accessible for at least ˜ 10 ^ 8 years.

Estimates of residence time and related variations in quality of ground water beneath Submarine Base Bangor and vicinity, Kitsap County, Washington

USGS Publications Warehouse

Cox, S.E.

2003-01-01

Estimates of residence time of ground water beneath Submarine Base Bangor and vicinity ranged from less than 50 to 4,550 years before present, based on analysis of the environmental tracers tritium, chlorofluorocarbons (CFCs), and carbon-14 (14C), in 33 ground-water samples collected from wells tapping the ground-water system. The concentrations of multiple environmental tracers tritium, CFCs, and 14C were used to classify ground water as modern (recharged after 1953), pre-modern (recharged prior to 1953), or indeterminate. Estimates of the residence time of pre-modern ground water were based on evaluation of 14C of dissolved inorganic carbon present in ground water using geochemical mass-transfer modeling to account for the interactions of the carbon in ground water with carbon of the aquifer sediments. Ground-water samples were obtained from two extensive aquifers and from permeable interbeds within the thick confining unit separating the sampled aquifers. Estimates of ground-water residence time for all ground-water samples from the shallow aquifer were less than 45 years and were classified as modern. Estimates of the residence time of ground water in the permeable interbeds within the confining unit ranged from modern to 4,200 years and varied spatially. Near the recharge area, residence times in the permeable interbeds typically were less than 800 years, whereas near the discharge area residence times were in excess of several thousand years. In the deeper aquifers, estimates of ground-water residence times typically were several thousand years but ranged from modern to 4,550 years. These estimates of ground-water residence time based on 14C were often larger than estimates of ground-water residence time developed by particle-tracking analysis using a ground-water flow model. There were large uncertainties?on the order of 1,000-2,000 years?in the estimates based on 14C. Modern ground-water tracers found in some samples from large-capacity production wells screened in the deeper aquifer may be the result of preferential ground-water pathways or induced downward flow caused by pumping stress. Spatial variations in water quality were used to develop a conceptual model of chemical evolution of ground water. Stable isotope ratios of deuterium and oxygen-18 in the 33 ground-water samples were similar, indicating similar climatic conditions and source of precipitation recharge for all of the sampled ground water. Oxidation of organic matter and mineral dissolution increased the concentrations of dissolved inorganic carbon and common ions in downgradient ground waters. However, the largest concentrations were not found near areas of ground-water discharge, but at intermediate locations where organic carbon concentrations were greatest. Dissolved methane, derived from microbial methanogenesis, was present in some ground waters. Methanogenesis resulted in substantial alteration of the carbon isotopic composition of ground water. The NETPATH geochemical model code was used to model mass-transfers of carbon affecting the 14C estimate of ground-water residence time. Carbon sources in ground water include dispersed particulate organic matter present in the confining unit separating the two aquifers and methane present in some ground water. Carbonate minerals were not observed in the lithologic material of the ground-water system but may be present, because they have been found in the bedrock of stream drainages that contribute sediment to the study area.

Basalt Petrogenesis Beneath Slow - and Ultraslow-Spreading Arctic Mid-Ocean Ridges

DTIC Science & Technology

2009-02-01

bed at night. I also want to thank the rest of my committee. Fred Frey, my advisor at MIT, was there to teach me and help me think critically ...times, and in the end analyzed some of my samples himself as a collaborator. As a colleague in the lab, and on the mass spectrometer this past year...systematics of basalts from the Juan de Fuca and Gorda Ridges by mass spectrometry. Earth Planet Sc Lett 96, 134-146. 16 Goldstein, S. J., Murrell

Groundwater and Leachate Monitoring and Sampling at ERDF, CY 2010

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weiss, R. L.; Lawrence, B. L.

2011-06-09

The purpose of this annual monitoring report is to evaluate the conditions of and identify trends for groundwater beneath the ERDF and report leachate results in fulfillment of the requirements specified in the ERDF ROD2 and the ERDF Amended ROD (EPA 1999). The overall objective of the groundwater monitoring program is to determine whether ERDF has impacted the groundwater. This objective is complicated by the fact that the ERDF is situated downgradient of the numerous groundwater contamination plumes originating from the 200 West Area.

Explosives Washout Lagoons Soils Operable Unit Supplemental Investigation Technical and Environmental Management Support of Installation Restoration Technology Development Program Umatilla Depot Activity Hermiston, Oregon

DTIC Science & Technology

1992-04-15

an ofcial endorsement or approval of the use of such commercial products. This report may not be cited for purposes of advertisement . "EngineersM M7...Logs Appendix C. Laboratory Results of Soil Samples Appendix D. Concentration of Contaminants vs . Depth in Soils Appendix E. Lithologic Profiles of...dramatic difference in concentrations of explosives in areas outside the lagoons vs . concentrations beneath the lagoons. The results confirm that ES-I

Moisture Monitoring at Area G, Technical Area 54, Los Alamos National Laboratory, 2016 Status Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Levitt, Daniel Glenn; Birdsell, Kay Hanson; Jennings, Terry L.

Hydrological characterization and moisture monitoring activities provide data required for evaluating the transport of subsurface contaminants in the unsaturated and saturated zones beneath Area G, and for the Area G Performance Assessment and Composite Analysis. These activities have been ongoing at Area G, Technical Area 54 of the Los Alamos National Laboratory since waste disposal operations began in 1957. This report summarizes the hydrological characterization and moisture monitoring activities conducted at Area G. It includes moisture monitoring data collected from 1986 through 2016 from numerous boreholes and access tubes with neutron moisture meters, as well as data collected by automatedmore » dataloggers for water content measurement sensors installed in a waste disposal pit cover, and buried beneath the floor of a waste disposal pit. This report is an update of a nearly identical report by Levitt et al., (2015) that summarized data collected through early 2015; this report includes additional moisture monitoring data collected at Pit 31 and the Pit 38 extension through December, 2016. It also includes information from the Jennings and French (2009) moisture monitoring report and includes all data from Jennings and French (2009) and the Draft 2010 Addendum moisture monitoring report (Jennings and French, 2010). For the 2015 version of this report, all neutron logging data, including neutron probe calibrations, were investigated for quality and pedigree. Some data were recalculated using more defensible calibration data. Therefore, some water content profiles are different from those in the Jennings and French (2009) report. All of that information is repeated in this report for completeness. Monitoring and characterization data generally indicate that some areas of the Area G vadose zone are consistent with undisturbed conditions, with water contents of less than five percent by volume in the top two layers of the Bandelier tuff at Area G. These data also indicate that other areas of the vadose zone are affected by waste disposal activities that have been ongoing at Area G since 1957, a period of nearly 60 years. In some areas, water content profiles indicate increases in water content to depths of tens of meters, especially in areas covered by asphalt and structures.« less

Surface wave tomography applied to the North American upper mantle

NASA Astrophysics Data System (ADS)

van der Lee, Suzan; Frederiksen, Andrew

Tomographic techniques that invert seismic surface waves for 3-D Earth structure differ in their definitions of data and the forward problem as well as in the parameterization of the tomographic model. However, all such techniques have in common that the tomographic inverse problem involves solving a large and mixed-determined set of linear equations. Consequently these inverse problems have multiple solutions and inherently undefinable accuracy. Smoother and rougher tomographic models are found with rougher (confined to great circle path) and smoother (finite-width) sensitivity kernels, respectively. A powerful, well-tested method of surface wave tomography (Partitioned Waveform Inversion) is based on inverting the waveforms of wave trains comprising regional S and surface waves from at least hundreds of seismograms for 3-D variations in S wave velocity. We apply this method to nearly 1400 seismograms recorded by digital broadband seismic stations in North America. The new 3-D S-velocity model, NA04, is consistent with previous findings that are based on separate, overlapping data sets. The merging of US and Canadian data sets, adding Canadian recordings of Mexican earthquakes, and combining fundamental-mode with higher-mode waveforms provides superior resolution, in particular in the US-Canada border region and the deep upper mantle. NA04 shows that 1) the Atlantic upper mantle is seismically faster than the Pacific upper mantle, 2) the uppermost mantle beneath Precambrian North America could be one and a half times as rigid as the upper mantle beneath Meso- and Cenozoic North America, with the upper mantle beneath Paleozoic North America being intermediate in seismic rigidity, 3) upper-mantle structure varies laterally within these geologic-age domains, and 4) the distribution of high-velocity anomalies in the deep upper mantle aligns with lower mantle images of the subducted Farallon and Kula plates and indicate that trailing fragments of these subducted oceanic plates still reside in the transition zone. The thickness of the high-velocity layer beneath Precambrian North America is estimated to be 250±70 km thick. On a smaller scale NA04 shows 1) high-velocities associated with subduction of the Pacific plate beneath the Aleutian arc, 2) the absence of expected high velocities in the upper mantle beneath the Wyoming craton, 3) a V-shaped dent below 150 km in the high-velocity cratonic lithosphere beneath New England, 4) the cratonic lithosphere beneath Precambrian North America being confined southwest of Baffin Bay, west of the Appalachians, north of the Ouachitas, east of the Rocky Mountains, and south of the Arctic Ocean, 5) the cratonic lithosphere beneath the Canadian shield having higher S-velocities than that beneath Precambrian basement that is covered with Phanerozoic sediments, 6) the lowest S velocities are concentrated beneath the Gulf of California, northern Mexico, and the Basin and Range Province.

Geochemistry of glacial sediments in the area of the Bend massive sulfide deposit, north-central Wisconsin

USGS Publications Warehouse

Woodruff, L.G.; Attig, J.W.; Cannon, W.F.

2004-01-01

Geochemical exploration in northern Wisconsin has been problematic because of thick glacial overburden and complex stratigraphic record of glacial history. To assess till geochemical exploration in an area of thick glacial cover and complex stratigraphy samples of glacial materials were collected from cores from five rotasonic boreholes near a known massive sulfide deposit, the Bend deposit in north-central Wisconsin. Diamond drilling in the Bend area has defined a long, thin zone of mineralization at least partly intersected at the bedrock surface beneath 30-40 m of unconsolidated glacial sediments. The bedrock surface has remnant regolith and saprolite resulting from pre-Pleistocene weathering. Massive sulfide and mineralized rock collected from diamond drill core from the deposit contain high (10s to 10,000s ppm) concentrations of Ag, As, Au, Bi, Cu, Hg, Se, Te, and Tl. Geochemical properties of the glacial stratigraphic units helped clarify the sequence and source areas of several glacial ice advances preserved in the section. At least two till sheets are recognized. Over the zone of mineralization, saprolite and preglacial alluvial and lacustrine samples are preserved on the bedrock surface in a paleoriver valley. The overlying till sheet is a gray, silty carbonate till with a source hundreds of kilometers to the northwest of the study area. This gray till is overlain by red, sandy till with a source to the north in Proterozoic rocks of the Lake Superior area. The complex glacial stratigraphy confounds down-ice geochemical till exploration. The presence of remnant saprolite, preglacial sediment, and far-traveled carbonate till minimized glacial erosion of mineralized material. As a result, little evidence of down-ice glacial dispersion of lithologic or mineralogic indicators of Bend massive sulfide mineralization was found in the samples from the rotasonic cores. This study points out the importance of determining glacial stratigraphy and history, and identifying favorable lithologies required for geochemical exploration. Drift prospecting in Wisconsin and other areas near the outer limits of the Pleistocene ice sheets may not be unsuccessful, in part, because of complex stratigraphic sequences of multiple glaciations where deposition dominates over erosion. ?? 2004 Elsevier B.V. All rights reserved.

Considerations for sampling inorganic constituents in ground water using diffusion samplers

USGS Publications Warehouse

Vroblesky, D.A.; Petkewich, M.D.; Campbell, T.R.; ,

2002-01-01

Data indicate that nylon-screen and dialysis diffusion samplers are capable of obtaining concentrations of inorganic solutes in ground water from wells that closely correspond to concentrations obtained by low-flow sampling. Conservative solutes, such as chloride, can be sampled by filling the diffusion samplers with oxygenated water. The samplers should be filled with anaerobic water for sampling redoxsensitive solutes. Oxidation of iron within the samplers, either by using aerobic fill water or by in-well oxygenation events, can lead to erroneous iron concentrations. Lithologic and chemical heterogeneity and sampler placement depth can lead to differences between concentrations from diffusion samples and low-flow samples because of mixing during pumping. A disadvantage of regenerated cellulose dialysis samplers is that they can begin to biodegrade within the two weeks of deployment. Nylon-screen samplers buried beneath streambed sediment along the unnamed tributary in a discharge zone of arseniccontaminated ground water were useful in locating the specific discharge zone.

Tomographic evidence for recent extension in the Bentley Subglacial Trench and a hotspot beneath Marie Byrd Land

NASA Astrophysics Data System (ADS)

Lloyd, A. J.; Wiens, D. A.; Nyblade, A.; Anandakrishnan, S.; Aster, R. C.; Huerta, A. D.; Wilson, T. J.; Shore, P.

2013-12-01

Here we present the first regional P and S wave relative velocity models of the upper mantle beneath much of West Antarctica using P and S wave relative travel time residuals from teleseismic events recorded by seismographs from the POLENET/ANET project. 21 of the seismographs form a sparse backbone network co-located with continuously recording GPS stations at rock sites throughout West Antarctica, and 17 stations formed a seismic transect extending from the Whitmore Mountains across the West Antarctic Rift System (WARS) and into Marie Byrd Land (MBL) with a station spacing of 90-100 km. Corrections for heterogeneities above the Moho, including the ice sheet, are applied to the relative travel time residuals using the receiver function models of Chaput et al., [submitted, 2013]. Both P and S wave velocity models indicate velocities faster than the mean of the model beneath the Whitmore Mountains that may be interpreted as thicker, colder lithosphere relative to the rest of West Antarctica. Slow velocity anomalies are observed beneath the Bentley Subglacial Trench (BST) and MBL. Slow velocities extending from the Moho to the transition zone beneath MBL are centered beneath the Mt Sidley volcano and coincide with high topography that is not isostatically supported by the crust [Chaput et al., submitted, 2013]. The slowest velocities occur at 200-300 km depth and are consistent with warm, low viscosity mantle that provides topographic support for the elevated MBL volcanic dome. Poor vertical resolution, typical of body wave tomography, hampers the models ability to resolve whether the anomaly beneath MBL is strictly an upper mantle hotspot or a classic mantle plume that extends into the lower mantle. The shallow (≤ 100 km depth) slow anomaly beneath the BST coincides with a region of thin crust and likely reflects a localized region of Cenozoic extension in the WARS that may have undergone a last phase of extension in the Neogene [Garnot et al., 2013]. Anomalously high heat flow reported by Fudge et al.[2012] at the WAIS divide ice core is also consistent with recent Neogene extension and a thermal perturbation suggested by both P and S tomography models. In general, the strong heterogeneities in our models are predominantly interpreted as reflecting upper mantle temperature variations in addition to possible mantle partial melting beneath MBL.

Big mantle wedge, anisotropy, slabs and earthquakes beneath the Japan Sea

NASA Astrophysics Data System (ADS)

Zhao, Dapeng

2017-09-01

The Japan Sea is a part of the western Pacific trench-arc-backarc system and has a complex bathymetry and intense seismic activities in the crust and upper mantle. Local seismic tomography revealed strong lateral heterogeneities in the crust and uppermost mantle beneath the eastern margin of the Japan Sea, which was determined using P and S wave arrival times of suboceanic earthquakes relocated precisely with sP depth phases. Ambient-noise tomography revealed a thin crust and a thin lithosphere beneath the Japan Sea and significant low-velocity (low-V) anomalies in the shallow mantle beneath the western and eastern margins of the Japan Sea. Observations with ocean-bottom seismometers and electromagnetometers revealed low-V and high-conductivity anomalies at depths of 200-300 km in the big mantle wedge (BMW) above the subducting Pacific slab, and the anomalies are connected with the low-V zone in the normal mantle wedge beneath NE Japan, suggesting that both shallow and deep slab dehydrations occur and contribute to the arc and back-arc magmatism. The Pacific slab has a simple geometry beneath the Japan Sea, and earthquakes occur actively in the slab down to a depth of ∼600 km beneath the NE Asian margin. Teleseismic P and S wave tomography has revealed that the Philippine Sea plate has subducted aseismically down to the mantle transition zone (MTZ, 410-660 km) depths beneath the southern Japan Sea and the Tsushima Strait, and a slab window is revealed within the aseismic Philippine Sea slab. Seismic anisotropy tomography revealed a NW-SE fast-velocity direction in the BMW, which reflects corner flows induced by the fast deep subduction of the Pacific slab. Large deep earthquakes (M > 7.0; depth > 500 km) occur frequently beneath the Japan Sea western margin, which may be related to the formation of the Changbai and Ulleung intraplate volcanoes. A metastable olivine wedge is revealed within the cold core of the Pacific slab at the MTZ depth, which may be related to the deep seismicity. However, many of these results are still preliminary, due to the lack of seismic stations in the Japan Sea. The key to resolving these critical geoscientific issues is seismic instrumentation in the Japan Sea, for which international cooperation of geoscience communities in the East Asian countries is necessary.

Application of continuous seismic-reflection techniques to delineate paleochannels beneath the Neuse River at US Marine Corps Air Station, Cherry Point, North Carolina

USGS Publications Warehouse

Cardinell, Alex P.

1999-01-01

A continuous seismic-reflection profiling survey was conducted by the U.S. Geological Survey on the Neuse River near the Cherry Point Marine Corps Air Station during July 7-24, 1998. Approximately 52 miles of profiling data were collected during the survey from areas northwest of the Air Station to Flanner Beach and southeast to Cherry Point. Positioning of the seismic lines was done by using an integrated navigational system. Data from the survey were used to define and delineate paleochannel alignments under the Neuse River near the Air Station. These data also were correlated with existing surface and borehole geophysical data, including vertical seismic-profiling velocity data collected in 1995. Sediments believed to be Quaternary in age were identified at varying depths on the seismic sections as undifferentiated reflectors and lack the lateral continuity of underlying reflectors believed to represent older sediments of Tertiary age. The sediments of possible Quaternary age thicken to the southeast. Paleochannels of Quaternary age and varying depths were identified beneath the Neuse River estuary. These paleochannels range in width from 870 feet to about 6,900 feet. Two zones of buried paleochannels were identified in the continuous seismic-reflection profiling data. The eastern paleochannel zone includes two large superimposed channel features identified during this study and in re-interpreted 1995 land seismic-reflection data. The second paleochannel zone, located west of the first paleochannel zone, contains several small paleochannels near the central and south shore of the Neuse River estuary between Slocum Creek and Flanner Beach. This second zone of channel features may be continuous with those mapped by the U.S. Geological Survey in 1995 using land seismic-reflection data on the southern end of the Air Station. Most of the channels were mapped at the Quaternary-Tertiary sediment boundary. These channels appear to have been cut into the older sediments and deepen in a southerly or downgradient direction. If these paleochannels continue beneath the Marine Corps Air Station and are filled with permeable sediment, they may act as conduits for ground-water flow or movement of contaminants between the surficial and underlying freshwater aquifers where confining units are breached.

Laboratory simulation of volcano seismicity.

PubMed

Benson, Philip M; Vinciguerra, Sergio; Meredith, Philip G; Young, R Paul

2008-10-10

The physical processes generating seismicity within volcanic edifices are highly complex and not fully understood. We report results from a laboratory experiment in which basalt from Mount Etna volcano (Italy) was deformed and fractured. The experiment was monitored with an array of transducers around the sample to permit full-waveform capture, location, and analysis of microseismic events. Rapid post-failure decompression of the water-filled pore volume and damage zone triggered many low-frequency events, analogous to volcanic long-period seismicity. The low frequencies were associated with pore fluid decompression and were located in the damage zone in the fractured sample; these events exhibited a weak component of shear (double-couple) slip, consistent with fluid-driven events occurring beneath active volcanoes.

Imaging the midcontinent rift beneath Lake Superior using large aperture seismic data

USGS Publications Warehouse

Tréhu, Anne M.; Morel-a-l'Huissier, Patrick; Meyer, R.; Hajnal, Z.; Karl, J.; Mereu, R.F.; Sexton, John L.; Shay, J.; Chan, W. K.; Epili, D.; Jefferson, T.; Shih, X. R.; Wendling, S.; Milkereit, B.; Green, A.; Hutchinson, Deborah R.

1991-01-01

We present a detailed velocity model across the 1.1 billion year old Midcontinent Rift System (MRS) in central Lake Superior. The model was derived primarily from onshore-offshore large-aperture seismic and gravity data. High velocities obtained within a highly reflective half-graben that was imaged on coincident seismic reflection data demonstrate the dominantly mafic composition of the graben fill and constrain its total thickness to be at least 30km. Strong wide-angle reflections are observed from the lower crust and Moho, indicating that the crust is thickest (55–60km) beneath the axis of the graben. The total crustal thickness decreases rapidly to about 40 km beneath the south shore of the lake and decreases more gradually to the north. Above the Moho is a high-velocity lower crust interpreted to result from syn-rift basaltic intrusion into and/or underplating beneath the Archean lower crust. The lower crust is thickest beneath the axis of the main rift half-graben. A second region of thick lower crust is found approximately 100km north of the axis of the rift beneath a smaller half graben that is interpreted to reflect an earlier stage of rifting. The crustal model presented here resembles recent models of some passive continental margins and is in marked contrast to many models of both active and extinct Phanerozoic continental rift zones. It demonstrates that the Moho is a dynamic feature, since the pre-rift Moho is probably within or above the high-velocity lower crust, whereas the post-rift Moho is defined as the base of this layer. In the absence of major tectonic activity, however, the Moho is very stable, since the large, abrupt variations in crustal thickness beneath the MRS have been preserved for at least a billion years.

Receiver function imaging of mantle transition zone discontinuities beneath the Tanzania Craton and the Eastern and Western Branches of the East African Rift System

NASA Astrophysics Data System (ADS)

Sun, M.; Liu, K. H.; Fu, X.; Gao, S. S.

2017-12-01

To investigate the mechanism of initiation and development of the Eastern African Rifting System (EARS) circumfluent the Tanzania Craton (TC), over 7,100 P-to-S radial receiver functions (RFs) recorded by 87 broadband seismic stations are stacked to map the topography of mantle transition zone (MTZ) discontinuities beneath the TC and the Eastern and Western Branches of the EARS. After time-depth conversion using the 1-D IASP91 Earth model, the resulting 410 km (d410) and 660 km (d660) discontinuity apparent depths are found to be greater than the global averages beneath the whole study area, implying slower than normal upper mantle velocities. The mean thickness of the MTZ beneath the Western Branch and TC is about 252 km, which is comparable to the global average and is inconsistent with the existence of present-day thermal upwelling originating from the lower mantle. In contrast, beneath the Eastern Branch, an 30 km thinning of the MTZ is observed from an up to 50 km and 20 km apparent depression of the d410 and d660, respectively. On the basis of previous seismic tomographic results and empirical relationships between velocity and thermal anomalies, we propose that the most plausible explanation for the observations beneath the volcanic Eastern Branch is the existence of a low-velocity layer extending from the surface to the upper MTZ, probably caused by decompression partial melting associated with continental rifting. The observations are in general agreement with an upper mantle origin for the initiation and development of both the Western and Eastern Branches of the EARS beneath the study area.

Finite Frequency Traveltime Tomography of Lithospheric and Upper Mantle Structures beneath the Cordillera-Craton Transition in Southwestern Canada

NASA Astrophysics Data System (ADS)

Chen, Y.; Gu, Y. J.; Hung, S. H.

2014-12-01

Based on finite-frequency theory and cross-correlation teleseismic relative traveltime data from the USArray, Canadian National Seismograph Network (CNSN) and Canadian Rockies and Alberta Network (CRANE), we present a new tomographic model of P-wave velocity perturbations for the lithosphere and upper mantle beneath the Cordillera-cration transition region in southwestern Canada. The inversion procedure properly accounts for the finite-volume sensitivities of measured travel time residuals, and the resulting model shows a greater resolution of upper mantle velocity heterogeneity beneath the study area than earlier approaches based on the classical ray-theoretical approach. Our model reveals a lateral change of P velocities from -0.5% to 0.5% down to ~200-km depth in a 50-km wide zone between the Alberta Basin and the foothills of the Rocky Mountains, which suggests a sharp structural gradient along the Cordillera deformation front. The stable cratonic lithosphere, delineated by positive P-velocity perturbations of 0.5% and greater, extends down to a maximum depth of ~180 km beneath the Archean Loverna Block (LB). In comparison, the mantle beneath the controversial Medicine Hat Block (MHB) exhibits significantly higher velocities in the uppermost mantle and a shallower (130-150 km depth) root, generally consistent with the average depth of the lithosphere-asthenosphere boundary beneath Southwest Western Canada Sedimentary Basin (WCSB). The complex shape of the lithospheric velocities under the MHB may be evidence of extensive erosion or a partial detachment of the Precambrian lithospheric root. Furthermore, distinct high velocity anomalies in LB and MHB, which are separated by 'normal' mantle block beneath the Vulcan structure (VS), suggest different Archean assembly and collision histories between these two tectonic blocks.

Delineating a road-salt plume in lakebed sediments using electrical resistivity, piezometers, and seepage meters at Mirror Lake, New Hampshire, U.S.A

USGS Publications Warehouse

Toran, Laura; Johnson, Melanie; Nyquist, Jonathan E.; Rosenberry, Donald O.

2010-01-01

Electrical-resistivity surveys, seepage meter measurements, and drive-point piezometers have been used to characterize chloride-enriched groundwater in lakebed sediments of Mirror Lake, New Hampshire, U.S.A. A combination of bottom-cable and floating-cable electrical-resistivity surveys identified a conductive zone (<100ohm-m)">(<100ohm-m)(<100ohm-m) overlying resistive bedrock (<1000ohm-m)">(<1000ohm-m)(<1000ohm-m)beneath the lake. Shallow pore-water samples from piezometers in lakebed sediments have chloride concentrations of 200–1800μeq/liter">200–1800μeq/liter200–1800μeq/liter, and lake water has a chloride concentration of 104μeq/liter">104μeq/liter104μeq/liter. The extent of the plume was estimated and mapped using resistivity and water-sample data. The plume (20×35m">20×35m20×35m wide and at least 3m">3m3m thick) extends nearly the full length and width of a small inlet, overlying the top of a basin formed by the bedrock. It would not have been possible to mapthe plume's shape without the resistivity surveys because wells provided only limited coverage. Seepage meters were installed approximately 40m">40m40m from the mouth of a small stream discharging at the head of the inlet in an area where the resistivity data indicated lake sediments are thin. These meters recorded in-seepage of chloride-enriched groundwater at rates similar to those observed closer to shore, which was unexpected because seepage usually declines away from shore. Although the concentration of road salt in the northeast inlet stream is declining, the plume map and seepage data indicate the groundwater contribution of road salt to the lake is not declining. The findings demonstrate the benefit of combining geophysical and hydrologic data to characterize discharge of a plume beneath Mirror Lake. The extent of the plume in groundwater beneath the lake and stream indicate there will likely be a long-term source of chloride to the lake from groundwater.

The 2009-11 SAHKE Experiment: Preliminary 3D Vp imaging across the interseismically locked southern Hikurangi margin, Wellington, New Zealand

NASA Astrophysics Data System (ADS)

Henrys, S. A.; Wech, A.; Sato, H.; Stern, T. A.; Okaya, D. A.; Iwasaki, T.; Savage, M. K.; Mochizuki, K.; Kurashimo, E.; Sutherland, R.

2013-12-01

We present a preliminary 3D Vp model from the Seismic Array HiKurangi Experiment (SAHKE). This joint project involving New Zealand, Japan, and US institutions aims to investigate the subduction zone fault characteristics beneath Wellington. Situated above where the Pacific Plate is subducting beneath the Australian plate at a rate of c. 42 mm/yr, the Wellington region provides a unique opportunity to investigate the frictional properties, geometry, and seismic potential of a shallow, locked megathrust fault. Here the coupled plate interface is 20-30 km deep beneath land and can be sampled with onshore/offshore data from 3 sides. We have published a 2D Vp model [Henrys et al., 2013] incorporating coast-to-coast onshore-offshore transect of 50 stations and utilising first arrivals from 2000 offshore MCS shots on either side. The transect velocity model also combined first arrivals from 800 stations with 100 m spacing recorded from 12 in-line, 500 kg onshore dynamite explosions. We have expanded the transect data to now include (i) first arrivals from the dense temporary array of 50 seismometers with c. 7 km spacing augmented with 25 regional network instruments to record 49 local and 45 teleseismic earthquakes over a four month period and (ii), 69,000 offshore airgun shots from 17 MCS lines crisscrossing two sides of the array. We combine all shot and earthquake recordings to simultaneously invert c. 750,000 first arrivals for velocity structure and hypocenters in the densely sampled volume. First results from 3D, Vp tomography and relocated hypocenters provide improved resolution over previous studies. Our improved velocity model provides a high-resolution geometry of the subducting plate to support interpretation of other phases identified in SAHKE shot gathers and local earthquakes. Henrys, S., A. Wech, R. Sutherland, T. Stern, M. Savage, H. Sato, K. Mochizuki, T. Iwasaki, D. Okaya, A. Seward, B. Tozer, J. Townend, E. Kurashimo, T. Iidaka, and T. Ishiyama (2013), SAHKE geophysical transect reveals crustal and subduction zone structure at the southern Hikurangi margin, New Zealand, Geochemistry, Geophysics, Geosystems.

Early Carboniferous (˜357 Ma) crust beneath northern Arabia: Tales from Tell Thannoun (southern Syria)

NASA Astrophysics Data System (ADS)

Stern, Robert J.; Ren, Minghua; Ali, Kamal; Förster, Hans-Jürgen; Al Safarjalani, Abdulrahman; Nasir, Sobhi; Whitehouse, Martin J.; Leybourne, Matthew I.; Romer, Rolf L.

2014-05-01

Continental crust beneath northern Arabia is deeply buried and poorly known. To advance our knowledge of this crust, we studied 8 xenoliths brought to the surface by Neogene eruptions of Tell Thannoun, S. Syria. The xenolith suite consists of two peridotites, one pyroxenite, four mafic granulites, and one charnockite. The four mafic granulites and charnockite are probably samples of the lower crust, and two mafic granulites gave 2-pyroxene equilibration temperatures of 780-800 °C, which we take to reflect temperatures at the time of formation. Peridotite and pyroxenite gave significantly higher temperatures of ∼900 °C, consistent with derivation from the underlying lithospheric mantle. Fe-rich peridotite yielded T∼800 °C, perhaps representing a cumulate layer in the crust. Three samples spanning the lithologic range of the suite (pyroxenite, mafic granulite, and charnockite) yielded indistinguishable concordant U-Pb zircon ages of ∼357 Ma, interpreted to approximate when these magmas crystallized. These igneous rocks are mostly juvenile additions from the mantle, as indicated by low initial 87Sr/86Sr (0.70312 to 0.70510) and strongly positive initial εNd(357 Ma) (+4 to +9.5). Nd model ages range from 0.55 to 0.71 Ga. We were unable to unequivocally infer a tectonic setting where these melts formed: convergent margin, rift, or hotspot. These xenoliths differ from those of Jordan and Saudi Arabia to the south in four principal ways: 1) age, being least 200 Ma younger than the presumed Neoproterozoic (533-1000 Ma) crust beneath Jordan and Saudi Arabia; 2) the presence of charnockite; 3) abundance of Fe-rich mafic and ultramafic lithologies; and 4) the presence of sapphirine. Our studies indicate that northern Arabian plate lithosphere contains a significant proportion of juvenile Late Paleozoic crust, the extent of which remains to be elucidated. This discovery helps explain fission track resetting documented for rocks from Israel and provides insights into the nature of Late Paleozoic (Hercynian) deformation that affected Arabia near the Persian Gulf.

Behavior of MORB magmas at uppermost mantle beneath a fast-spreading axis: an example from Wadi Fizh of the northern Oman ophiolite

NASA Astrophysics Data System (ADS)

Akizawa, Norikatsu; Arai, Shoji; Tamura, Akihiro

2012-10-01

Relationships of lithologies in uppermost mantle section of Oman ophiolite are highly complicated, harzburgites especially being closely associated with dunites, wehrlites, and gabbros. The petrology and geochemistry of the uppermost mantle section provide constrains on how MORB (mid-ocean ridge basalt) magmas migrate from the mantle to crust. We conducted detailed sampling at the uppermost mantle section of the northern Oman ophiolite (along Wadi Fizh), and it provides us with centimeter-scale lithological and mineral chemical heterogeneity. In particular, we found peculiar plagioclase-free harzburgites that have not been recorded from the current ocean floor, which contain high-Mg# [Mg/(Mg + Fe2+) atomic ratio] clinopyroxenes that are almost in equilibrium (saturated) with MORB in terms of REE concentrations. They are from the uppermost mantle section underlying the wehrlite-dunite layer (=Moho transition zone; MTZ) just beneath the layered gabbro. MORBs cannot be in equilibrium with harzburgites; however, we call the peculiar harzburgites as "MORB-saturated harzburgite" for simplicity in this paper. The MORB-saturated harzburgites exhibit slightly enriched mineralogy (e.g., spinels with higher Ti and ferric iron, and clinopyroxenes with higher Ti and Na) and contain slightly but clearly more abundant modal clinopyroxene (up to 3.5 vol.%) than ordinary Oman depleted harzburgites (less than 1 vol.% clinopyroxene), which are similar to abyssal harzburgites. Gabbro-clinopyroxenite bands, which were melt lenses beneath the ridge axis, are dominant around the MTZ. Detailed sampling around the gabbro-clinopyroxenite bands revealed that the MORB-saturated harzburgites appear around the bands. The interaction between a melt that was MORB-like and an ordinary harzburgite induced incongruent melting of orthopyroxenes in harzburgites, and the melt chromatographically intruded into the wall harzburgite and was modified to coexist with olivine and two pyroxenes at low melt/harzburgite ratios. The modified melt left clinopyroxene (not clinopyroxene + plagioclase as in plagioclase-impregnated abyssal harzburgite) to form the MORB-saturated harzburgites in the vicinity (harzburgite) of the fracture, which are left as gabbro-clinopyroxenite bands. This local modification mimics the whole lithological and chemical variation of the MTZ and makes chemical variation of MORB suite at fast-spreading ridge.

Using P-wave Triplications to Constrain the Mantle Transition Zone beneath Central Iranian Plateau and Surrounding Area

NASA Astrophysics Data System (ADS)

Chi, H. C.; Tseng, T. L.

2014-12-01

The Iranian Plateau is a tectonically complex region resulting from the continental collision between the African and Eurasian plates. The convergence of the two continents created the Zagros Mountains, the high topography southwest of Iran, and active seismicity along the Zagros-Bitlis suture. Tomographic studies in Iran reveal low seismic speeds and high attenuation of Sn wave in the uppermost mantle beneath the Iranian Plateau relative to adjacent regions. The deeper structure, however, remains curiously inconclusive. By contrast, a prominent fast seismic anomaly is found under central Tibet near depth of 600 km in the mantle transition zone (TZ), and it is speculated to be the remnant of lithosphere detached during the continental collision. We conduct a comparative study that utilizes triplicate arrivals of high-resolution P waveforms to investigate the velocity structure of mantle beneath the central Iranian Plateau and surroundings. Due to the abrupt increase in seismic wave speeds and density across the 410- and 660-km discontinuities, seismic waves at epicentral distances of 15-30 degrees would form multiple arrivals and the relative times and amplitudes between them are most sensitive to the variations in seismic speeds near the TZ. We combine several broadband arrays to construct 8 seismic profiles, each about 800 km long, that mainly sample the TZ under central Iranian Plateau, Turan shield and part of South Caspian basin. Move-outs between arrivals are clear in the profiles. Relative timings suggest a slightly smaller 660-km contrast under stable Turan shield. In the next stage, it is necessary to model waveforms after the source effect being removed properly. Our preliminary tests show that the F-K method can efficiently calculate the synthetic seismograms. We will determine the 1D velocity model for each sampled sector by minimizing the overall misfits between observed and predicted waveforms. The lateral variations may be further explored by comparing adjacent sectors. The results are important for understanding the lithosphere-mantle interaction during the process of continental collision.

The bactericidal effect of shock waves

NASA Astrophysics Data System (ADS)

Leighs, J. A.; Appleby-Thomas, G. J.; Wood, D. C.; Goff, M. J.; Hameed, A.; Hazell, P. J.

2014-05-01

There are a variety of theories relating to the origins of life on our home planet, some of which discuss the possibility that life may have been spread via inter-planetary bodies. There have been a number of investigations into the ability of life to withstand the likely conditions generated by asteroid impact (both contained in the impactor and buried beneath the planet surface). Previously published data regarding the ability of bacteria to survive such applied shockwaves has produced conflicting conclusions. The work presented here used an established and published technique in combination with a single stage gas gun, to shock and subsequently recover Escherichia coli populations suspended in a phosphate buffered saline solution. Peak pressure across the sample region was calculated via numerical modelling. Survival data against peak sample pressure for recovered samples is presented alongside control tests. SEM micrographs of shocked samples are presented alongside control sets to highlight key differences between cells in each case.

Perspectives of mid-infrared optical coherence tomography for inspection and micrometrology of industrial ceramics

PubMed Central

Su, Rong; Kirillin, Mikhail; Chang, Ernest W.; Sergeeva, Ekaterina; Yun, Seok H.; Mattsson, Lars

2014-01-01

Optical coherence tomography (OCT) is a promising tool for detecting micro channels, metal prints, defects and delaminations embedded in alumina and zirconia ceramic layers at hundreds of micrometers beneath surfaces. The effect of surface roughness and scattering of probing radiation within sample on OCT inspection is analyzed from the experimental and simulated OCT images of the ceramic samples with varying surface roughnesses and operating wavelengths. By Monte Carlo simulations of the OCT images in the mid-IR the optimal operating wavelength is found to be 4 µm for the alumina samples and 2 µm for the zirconia samples for achieving sufficient probing depth of about 1 mm. The effects of rough surfaces and dispersion on the detection of the embedded boundaries are discussed. Two types of image artefacts are found in OCT images due to multiple reflections between neighboring boundaries and inhomogeneity of refractive index. PMID:24977838

Three-dimensional crustal structure of Long Valley caldera, California, and evidence for the migration of CO2 under Mammoth Mountain

USGS Publications Warehouse

Foulger, G.R.; Julian, B.R.; Pitt, A.M.; Hill, D.P.; Malin, P.E.; Shalev, E.

2003-01-01

A temporary network of 69 three-component seismic stations captured a major seismic sequence in Long Valley caldera in 1997. We performed a tomographic inversion for crustal structure beneath a 28 km ?? 16 km area encompassing part of the resurgent dome, the south moat, and Mammoth Mountain. Resolution of crustal structure beneath the center of the study volume was good down to ???3 km below sea level (???5 km below the surface). Relatively high wave speeds are associated with the Bishop Tuff and lower wave speeds characterize debris in the surrounding moat. A low-Vp/Vs anomaly extending from near the surface to ???1 km below sea level beneath Mammoth Mountain may represent a CO2 reservoir that is supplying CO2-rich springs, venting at the surface, and killing trees. We investigated temporal variations in structure beneath Mammoth Mountain by differencing our results with tomographic images obtained using data from 1989/1990. Significant changes in both Vp and Vs were consistent with the migration of CO2 into the upper 2 km or so beneath Mammoth Mountain and its depletion in peripheral volumes that correlate with surface venting areas. Repeat tomography is capable of detecting the migration of gas beneath active silicic volcanoes and may thus provide a useful volcano monitoring tool.