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Sample records for geochemistry water dynamics

  1. Geochemistry

    ERIC Educational Resources Information Center

    Ailin-Pyzik, Iris B.; Sommer, Sheldon E.

    1977-01-01

    Enumerates some of the research findings in geochemistry during the last year, including X-ray analysis of the Mars surface, trace analysis of fresh and esterarine waters, and analysis of marine sedements. (MLH)

  2. Dynamical geochemistry of the mantle

    NASA Astrophysics Data System (ADS)

    Davies, G. F.

    2011-09-01

    The reconciliation of mantle chemistry with the structure of the mantle inferred from geophysics and dynamical modelling has been a long-standing problem. This paper reviews three main aspects. First, extensions and refinements of dynamical modelling and theory of mantle processing over the past decade. Second, a recent reconsideration of the implications of mantle heterogeneity for melting, melt migration, mantle differentiation and mantle segregation. Third, a recent proposed shift in the primitive chemical baseline of the mantle inferred from observations of non-chondritic 142Nd in the Earth. It seems most issues can now be resolved, except the level of heating required to maintain the mantle's thermal evolution. A reconciliation of refractory trace elements and their isotopes with the dynamical mantle, proposed and given preliminary quantification by Hofmann, White and Christensen, has been strengthened by work over the past decade. The apparent age of lead isotopes and the broad refractory-element differences among and between ocean island basalts (OIBs) and mid-ocean ridge basalts (MORBs) can now be quantitatively accounted for with some assurance. The association of the least radiogenic helium with relatively depleted sources and their location in the mantle have been enigmatic. The least radiogenic helium samples have recently been recognised as matching the proposed non-chondritic primitive mantle. It has also been proposed recently that noble gases reside in a so-called hybrid pyroxenite assemblage that is the result of melt from fusible pods reacting with surrounding refractory peridotite and refreezing. Hybrid pyroxenite that is off-axis may not remelt and erupt at MORs, so its volatile constituents would recirculate within the mantle. Hybrid pyroxenite is likely to be denser than average mantle, and thus some would tend to settle in the D" zone at the base of the mantle, along with some old subducted oceanic crust. Residence times in D" are longer, so

  3. Geochemistry.

    ERIC Educational Resources Information Center

    Fyfe, William S.

    1979-01-01

    Techniques in geochemistry continue to improve in sensitivity and scope. The exciting areas of geochemistry still include the classical fields of the origin of the elements and objects in space, but environmental crisis problems are important as well. (Author/BB)

  4. Geochemistry

    SciTech Connect

    Foster, N.H.; Beaumont, E.A.

    1988-01-01

    Papers in this text are part of a reprint series designed to be useful to those involved in petroleum exploration and development. The authors divide the topic of geochemistry into four sections: (1) petroleum formation,(2) source rock evaluation, (3) migration, and (4) surface geochemistry. Petroleum formation contains papers that discuss accumulation and preservation of organic matter, conversion to kerogen, conversion to petroleum, and effects that different types of kerogen have on the types of petroleum generated. The section on source rocks contain papers that review methods for estimating total organic content of source rocks, potential amount of petroleum they can expel, and quantity of petroleum expelled from these source rocks.Migration deals with mechanisms for expulsion and migration of petroleum from source rocks and in carrier beds. The section on surface geochemistry discusses the problems associated with using geochemical methods in exploration.

  5. Geochemistry of surface waters of Vojvodina, Yugoslavia

    NASA Astrophysics Data System (ADS)

    Berry Lyons, W.; Lent, Robert M.; Djukic, Nada; Maletin, Steven; Pujin, Vlasta; Carey, Anne E.

    1992-08-01

    Major elements data are presented for a number of surface water samples from the Vojvodina region of Yugoslavia. These include samples from the Danube and Tisa Rivers as well as from three lakes in the Pannonian Plain. The data indicate that surface waters evolved to two major water types: Na-CO 3-SO 4-Cl and Na-Cl. The chemical composition of the surface water from this region has been strongly affected by anthropogenic activities including irrigation and the direct introduction of various chemical species, especially Na and Cl. It appears that the major element chemistry of a number of lakes in this region has changed since the 1950s.

  6. GEOCHEMISTRY OF SULFUR IN IRON CORROSION SCALES FOUND IN DRINKING WATER DISTRIBUTION SYSTEMS

    EPA Science Inventory

    Iron-sulfur geochemistry is important in many natural and engineered environments, including drinking water systems. In the anaerobic environment beneath scales of corroding iron drinking water distribution system pipes, sulfate reducing bacteria (SRB) produce sulfide from natu...

  7. Relating salt marsh pore water geochemistry patterns to vegetation zones and hydrologic influences

    NASA Astrophysics Data System (ADS)

    Moffett, Kevan B.; Gorelick, Steven M.

    2016-03-01

    Physical, chemical, and biological factors influence vegetation zonation in salt marshes and other wetlands, but connections among these factors could be better understood. If salt marsh vegetation and marsh pore water geochemistry coorganize, e.g., via continuous plant water uptake and persistently unsaturated sediments controlling vegetation zone-specific pore water geochemistry, this could complement known physical mechanisms of marsh self-organization. A high-resolution survey of pore water geochemistry was conducted among five salt marsh vegetation zones at the same intertidal elevation. Sampling transects were arrayed both parallel and perpendicular to tidal channels. Pore water geochemistry patterns were both horizontally differentiated, corresponding to vegetation zonation, and vertically differentiated, relating to root influences. The geochemical patterns across the site were less broadly related to marsh hydrology than to vegetation zonation. Mechanisms contributing to geochemical differentiation included: root-induced oxidation and nutrient (P) depletion, surface and creek-bank sediment flushing by rainfall or tides, evapotranspiration creating aerated pore space for partial sediment flushing in some areas while persistently saturated conditions hindered pore water renewal in others, and evapoconcentration of pore water solutes overall. The concentrated pore waters draining to the tidal creeks accounted for 41% of ebb tide solutes (median of 14 elements), including being a potentially toxic source of Ni but a slight sink for Zn, at least during the short, winter study period in southern San Francisco Bay. Heterogeneous vegetation effects on pore water geochemistry are not only significant locally within the marsh but may broadly influence marsh-estuary solute exchange and ecology.

  8. Geochemistry and the understanding of ground-water systems

    NASA Astrophysics Data System (ADS)

    Glynn, Pierre D.; Plummer, L. Niel

    2005-03-01

    Geochemistry has contributed significantly to the understanding of ground-water systems over the last 50 years. Historic advances include development of the hydrochemical facies concept, application of equilibrium theory, investigation of redox processes, and radiocarbon dating. Other hydrochemical concepts, tools, and techniques have helped elucidate mechanisms of flow and transport in ground-water systems, and have helped unlock an archive of paleoenvironmental information. Hydrochemical and isotopic information can be used to interpret the origin and mode of ground-water recharge, refine estimates of time scales of recharge and ground-water flow, decipher reactive processes, provide paleohydrological information, and calibrate ground-water flow models. Progress needs to be made in obtaining representative samples. Improvements are needed in the interpretation of the information obtained, and in the construction and interpretation of numerical models utilizing hydrochemical data. The best approach will ensure an optimized iterative process between field data collection and analysis, interpretation, and the application of forward, inverse, and statistical modeling tools. Advances are anticipated from microbiological investigations, the characterization of natural organics, isotopic fingerprinting, applications of dissolved gas measurements, and the fields of reaction kinetics and coupled processes. A thermodynamic perspective is offered that could facilitate the comparison and understanding of the multiple physical, chemical, and biological processes affecting ground-water systems. La géochimie a contribué de façon importante à la compréhension des systèmes d'eaux souterraines pendant les 50 dernières années. Les avancées ont portées sur le développement du concept des faciès hydrochimiques, sur l'application de la théorie des équilibres, l'étude des processus d'oxydoréduction, et sur la datation au radiocarbone. D'autres concepts, outils et

  9. Geochemistry and the understanding of ground-water systems

    NASA Astrophysics Data System (ADS)

    Glynn, Pierre D.; Plummer, L. Niel

    2005-03-01

    Geochemistry has contributed significantly to the understanding of ground-water systems over the last 50 years. Historic advances include development of the hydrochemical facies concept, application of equilibrium theory, investigation of redox processes, and radiocarbon dating. Other hydrochemical concepts, tools, and techniques have helped elucidate mechanisms of flow and transport in ground-water systems, and have helped unlock an archive of paleoenvironmental information. Hydrochemical and isotopic information can be used to interpret the origin and mode of ground-water recharge, refine estimates of time scales of recharge and ground-water flow, decipher reactive processes, provide paleohydrological information, and calibrate ground-water flow models. Progress needs to be made in obtaining representative samples. Improvements are needed in the interpretation of the information obtained, and in the construction and interpretation of numerical models utilizing hydrochemical data. The best approach will ensure an optimized iterative process between field data collection and analysis, interpretation, and the application of forward, inverse, and statistical modeling tools. Advances are anticipated from microbiological investigations, the characterization of natural organics, isotopic fingerprinting, applications of dissolved gas measurements, and the fields of reaction kinetics and coupled processes. A thermodynamic perspective is offered that could facilitate the comparison and understanding of the multiple physical, chemical, and biological processes affecting ground-water systems. La géochimie a contribué de façon importante à la compréhension des systèmes d'eaux souterraines pendant les 50 dernières années. Les avancées ont portées sur le développement du concept des faciès hydrochimiques, sur l'application de la théorie des équilibres, l'étude des processus d'oxydoréduction, et sur la datation au radiocarbone. D'autres concepts, outils et

  10. The lipid geochemistry of interstitial waters of recent marine sediments

    SciTech Connect

    Saliot, A.; Brault, M.; Boussuge, C. )

    1988-04-01

    To elucidate the nature of biogeochemical processes occurring at the water-sediment interface, the authors have analyzed fatty acids, n-alkanes and sterols contained in interstitial waters collected from oxic and anoxic marine sediments in the eastern and western intertropical Atlantic Ocean and in the Arabian Sea. Lipid concentrations in interstitial waters vary widely and are generally much higher than concentrations encountered in the overlying sea water. Higher concentrations in interstitial water are observed in environments favorable for organic input and preservation of the organic matter in the water column and in the surficial sediment. The analysis of biogeochemical markers in the various media of occurrence of the organic matter such as sea water, suspended particles, settling particles and sediment is discussed in terms of differences existing between these media and bio-transformations of the organic matter at the water-sediment interface.

  11. 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.

  12. Geochemistry of formation water, Pliocene-Pleistocene reservoirs, offshore Louisiana

    SciTech Connect

    Land, L.S.; MacPherson, G.L. )

    1989-09-01

    The total dissolved solids content of formation water from Pliocene-Pleistocene reservoirs, offshore Louisiana, is dominated by NaCl derived from the dissolution and recrystallization of diapiric salt. Other solutes, and the water itself, are derived from primary pore water (originally seawater, subsequently modified by sulfate reduction and methanogenesis) from mineralogically immature late Cenozoic marine clastics. {sup 18}O values between 0 and +2 {per thousand} (SMOW), coupled with nonradiogenic {sup 87}Sr/{sup 86}Sr ratios, demonstrate that the water has undergone little interaction with detrital silicates (smectite or detrital feldspars) prior to emplacement in the reservoirs. Water from Pliocene-Pleistocene reservoir rocks contrasts with water from nearby, onshore Miocene reservoirs, which is largely derived from more mineralogically mature Cenozoic clastic sediments. Low Ca, Ba, Li, B, and Br in both Miocene and Pliocene-Pleistocene water samples from offshore Louisiana indicate little contribution from Ca-rich water characteristic of deep-seated Mesozoic reservoirs. A few samples of formation water associated with diapiric salt structures could contain up to about 10% solutes derived from deep-seated Mesozoic sources, however.

  13. Geochemistry of Standard Mine Waters, Gunnison County, Colorado, July 2009

    USGS Publications Warehouse

    Verplanck, Philip L.; Manning, Andrew H.; Graves, Jeffrey T.; McCleskey, R. Blaine; Todorov, Todor; Lamothe, Paul J.

    2009-01-01

    In many hard-rock-mining districts water flowing from abandoned mine adits is a primary source of metals to receiving streams. Understanding the generation of adit discharge is an important step in developing remediation plans. In 2006, the U.S. Environmental Protection Agency listed the Standard Mine in the Elk Creek drainage basin near Crested Butte, Colorado as a superfund site because drainage from the Standard Mine enters Elk Creek, contributing dissolved and suspended loads of zinc, cadmium, copper, and other metals to the stream. Elk Creek flows into Coal Creek, which is a source of drinking water for the town of Crested Butte. In 2006 and 2007, the U.S. Geological Survey undertook a hydrogeologic investigation of the Standard Mine and vicinity and identified areas of the underground workings for additional work. Mine drainage, underground-water samples, and selected spring water samples were collected in July 2009 for analysis of inorganic solutes as part of a follow-up study. Water analyses are reported for mine-effluent samples from Levels 1 and 5 of the Standard Mine, underground samples from Levels 2 and 3 of the Standard Mine, two spring samples, and an Elk Creek sample. Reported analyses include field measurements (pH, specific conductance, water temperature, dissolved oxygen, and redox potential), major constituents and trace elements, and oxygen and hydrogen isotopic determinations. Overall, water samples collected in 2009 at the same sites as were collected in 2006 have similar chemical compositions. Similar to 2006, water in Level 3 did not flow out the portal but was observed to flow into open workings to lower parts of the mine. Many dissolved constituent concentrations, including calcium, magnesium, sulfate, manganese, zinc, and cadmium, in Level 3 waters substantially are lower than in Level 1 effluent. Concentrations of these dissolved constituents in water samples collected from Level 2 approach or exceed concentrations of Level 1 effluent

  14. Geochemistry of oil-field water from the North Slope

    SciTech Connect

    Kharaka, Y.K.; Carothers, W.W.

    1989-01-01

    Knowledge of the chemical composition of oil-field water is important in understanding the origin and migration of petroleum as well as the water mineral reactions that affect the porosity and permeability of the reservoir rocks. This knowledge is essential in interpreting electric logs and in determining potential pollution, corrosion, and disposal problems of water produced with oil and gas. Finally, the chemical composition of water is an important factor in determining the conditions (temperature, pressure) for the formation of clathrates. This chapter reports detailed chemical analyses of seven formation-water samples from wells within the NPRA and one surface-and two formation-water samples from the Prudhoe Bay oil field. The authors also report {delta}D and {delta}{sup 18}O values for eight of the water samples as well as analyses for gases from six wells. The formation-water samples were obtained from depths ranging from about 700 to 2800 m and from reservoir rocks ranging in age from Mississippian (Lisburne Group) to Triassic. The reservoir rocks are sandstone except for sample 79-AK-5, which was obtained from a limestone interbedded with sandstone. Generally, the pre-Cretaceous sandstone reservoir rocks on the North Slope have a similar mineral composition. Van de Kamp (1979) gave the following description of these sandstones: Quartz (usually monocrystalline) and chert are the major components; carbonate and clay are variable. Carbonate occurs as detrital grains and as cement, siderite being the most common type. Siderite can form as much as 30 percent of the rock. Clay occurs as a common matrix, generally making up less than 10 percent of the rock. Accessory minerals include pyrite, plagioclase, microcline, glauconite, zircon, sphene, tourmaline, and muscovite.

  15. Coral skeletal geochemistry as a monitor of inshore water quality.

    PubMed

    Saha, Narottam; Webb, Gregory E; Zhao, Jian-Xin

    2016-10-01

    Coral reefs maintain extraordinary biodiversity and provide protection from tsunamis and storm surge, but inshore coral reef health is degrading in many regions due to deteriorating water quality. Deconvolving natural and anthropogenic changes to water quality is hampered by the lack of long term, dated water quality data but such records are required for forward modelling of reef health to aid their management. Reef corals provide an excellent archive of high resolution geochemical (trace element) proxies that can span hundreds of years and potentially provide records used through the Holocene. Hence, geochemical proxies in corals hold great promise for understanding changes in ancient water quality that can inform broader oceanographic and climatic changes in a given region. This article reviews and highlights the use of coral-based trace metal archives, including metal transported from rivers to the ocean, incorporation of trace metals into coral skeletons and the current 'state of the art' in utilizing coral trace metal proxies as tools for monitoring various types of local and regional source-specific pollution (river discharge, land use changes, dredging and dumping, mining, oil spills, antifouling paints, atmospheric sources, sewage). The three most commonly used coral trace element proxies (i.e., Ba/Ca, Mn/Ca, and Y/Ca) are closely associated with river runoff in the Great Barrier Reef, but considerable uncertainty remains regarding their complex biogeochemical cycling and controlling mechanisms. However, coral-based water quality reconstructions have suffered from a lack of understanding of so-called vital effects and early marine diagenesis. The main challenge is to identify and eliminate the influence of extraneous local factors in order to allow accurate water quality reconstructions and to develop alternate proxies to monitor water pollution. Rare earth elements have great potential as they are self-referencing and reflect basic terrestrial input. PMID

  16. Development and deployment of a deep-sea Raman probe for measurement of pore water geochemistry

    NASA Astrophysics Data System (ADS)

    Zhang, Xin; Walz, Peter M.; Kirkwood, William J.; Hester, Keith C.; Ussler, William; Peltzer, Edward T.; Brewer, Peter G.

    2010-02-01

    We have developed, deployed, and tested a novel probe for study of the geochemistry of sediment pore waters based upon Raman spectroscopy. The Raman technique has already been used successfully for in situ measurements of targets of scientific interest including gas and hydrothermal vents and complex gas hydrates, but sediment geochemistry has so far been an intractable problem since the sediments themselves are strongly fluorescent and typically only very small sample volumes are obtainable. The 35 cm long probe extracts pore fluids through a 10 μm sintered metallic frit and draws the sample through a 2 mm diameter channel into a sapphire windowed optical cell within which the laser beam is focused and the spectrum recorded. The dead volume of the system is ˜1 ml and the instrument is ROV deployable with activation of probe insertion and sample withdrawal under direct operator control. The unique features of this mode of detection include observation of the sulfate gradient in marine pore waters as an indicator of diagenesis, direct measurement of the dissolved sulfide species H 2S and HS -, and measurement of dissolved methane; all of which are of primary geochemical interest. Quantitative analysis is achieved by area ratio to known water peaks and from standard calibration curves with a precision of ±5%. We find only very small fluorescence from pore waters measured in situ, but observe rapid increases in fluorescence from cores returned to the surface and exposed to oxygen.

  17. Strontium isotope characterization and major ion geochemistry of karst water flow, Shentou, northern China

    NASA Astrophysics Data System (ADS)

    Wang, Yanxin; Guo, Qinghai; Su, Chunli; Ma, Teng

    2006-09-01

    SummaryKarst water is the most important source of water supply for Shanxi province, northern China. The Shentou springs are representative of the 19 major karst springs at Shanxi. The total area of the Shentou karst water system is 5316 km 2, the Middle Ordovician limestone being its major karst aquifer. In this study, data about the strontium isotope geochemistry and major ion hydrochemistry were analyzed to understand the flow patterns and hydrogeochemical processes of karst water at Shentou. The contour map of TDS value of karst water and that of Sr concentration are similar, showing the general tendency of increase from the northern, western and southern boundary to the discharge area. The average values of 87Sr/ 86Sr ratios of karst water decrease from recharge (0.7107) to discharge area (0.7102), evolving towards those of limestone hostrocks. Comparison of 87Sr/ 86Sr ratios with Sr content suggests that isotopic compositions of some karst water samples from the recharge and flow through area should be the result of interaction between aquifer limestone matrix and strontium-poor recharge waters of meteoric origin. However, for samples from the discharge area that are plotted above the mixing line, mixing with groundwater in the Quaternary aquifers with high 87Sr/ 86Sr ratios may be another factor controlling Sr isotope chemistry. Two major groundwater flow paths were discerned from hydrogeological and geochemical data. Along both flow paths, the 87Sr/ 86Sr ratios of karst water show a general tendency of decrease. Geochemical modeling of the major ion geochemistry of karst water using PHREEQC also indicates that the chemistry of springs should be affected by the incorporation of groundwater in Quaternary aquifer. The effect of the mixing action on the spring hydrochemistry in flow path 1 is more remarkable than that in flow path 2, according to different mixing ratios in both paths (30% in flow path 1 and 5% in flow path 2).

  18. Stable isotope geochemistry of East African waters. [Abstract only

    SciTech Connect

    Sayer, M.D.; Cerling, T.E.; Bowman, J.R.

    1983-03-01

    Lakes and Rivers in East Africa have varied stable isotopic compositions. Lakes exhibit enriched delta13-C values (-2 to +5%), while their inflowing rivers show depleted values (-15 to -8%). Hot springs and standing pools of water have intermediate values. Some small lakes are extremely variable in delta18-0 or deltaD (+2 to +8% and +20 to +40%, respectively for Lake Naivasha), whereas larger lakes are relatively constant for long periods of time (+5.6 to 6.1 and +36 to 40, respectively for Lake Turkana). Isotopic values are unrelated to salinity for comparison between lakes. Stable isotopes also reveal the sources of hot spring discharges: the Kapedo hot springs probably originate from Maralel and not from Lake Baringo as local legend has it; the hot springs north of Lake Naivasha are of meteoric origin while those to the south of Lake Naivasha have similar isotopic compositions to Lake Naivasha.

  19. Geochemistry of clathrate-derived methane in Arctic Ocean waters

    SciTech Connect

    Elliott, S.M.; Reagan, M.T.; Moridis, G.J.; Cameron-Smith, P.J.

    2010-03-15

    Alterations to the composition of seawater are estimated for microbial oxidation of methane from large polar clathrate destabilizations, which may arise in the coming century. Gas fluxes are taken from porous flow models of warming Arctic sediment. Plume spread parameters are then used to bracket the volume of dilution. Consumption stoichiometries for the marine methanotrophs are based on growth efficiency and elemental/enzyme composition data. The nutritional demand implied by extra CH{sub 4} removal is compared with supply in various high latitude water masses. For emissions sized to fit the shelf break, reaction potential begins at one hundred micromolar and falls to order ten a thousand kilometers downstream. Oxygen loss and carbon dioxide production are sufficient respectively to hypoxify and acidify poorly ventilated basins. Nitrogen and the monooxygenase transition metals may be depleted in some locations as well. Deprivation is implied relative to existing ecosystems, along with dispersal of the excess dissolved gas. Physical uncertainties are inherent in the clathrate abundance, patch size, outflow buoyancy and mixing rate. Microbial ecology is even less defined but may involve nutrient recycling and anaerobic oxidizers.

  20. Seasonal variations in pore water and sediment geochemistry of littoral lake sediments (Asylum Lake, MI, USA)

    PubMed Central

    Koretsky, Carla M; Haas, Johnson R; Miller, Douglas; Ndenga, Noah T

    2006-01-01

    Background Seasonal changes in pore water and sediment redox geochemistry have been observed in many near-surface sediments. Such changes have the potential to strongly influence trace metal distribution and thus create seasonal fluctuations in metal mobility and bioavailability. Results Seasonal trends in pore water and sediment geochemistry are assessed in the upper 50 cm of littoral kettle lake sediments. Pore waters are always redox stratified, with the least compressed redox stratification observed during fall and the most compressed redox stratification observed during summer. A 2-step sequential sediment extraction yields much more Fe in the first step, targeted at amorphous Fe(III) (hydr)oxides (AEF), then in the second step, which targets Fe(II) monosulfides. Fe extracted in the second step is relatively invariant with depth or season. In contrast, AEF decreases with sediment depth, and is seasonally variable, in agreement with changes in redox stratification inferred from pore water profiles. A 5-step Tessier extraction scheme was used to assess metal association with operationally-defined exchangeable, carbonate, iron and manganese oxide (FMO), organic/sulfide and microwave-digestible residual fractions in cores collected during winter and spring. Distribution of metals in these two seasons is similar. Co, As, Cd, and U concentrations approach detection limits. Fe, Cu and Pb are mostly associated with the organics/sulfides fraction. Cr and Zn are mostly associated with FMO. Mn is primarily associated with carbonates, and Co is nearly equally distributed between the FMO and organics/sulfide fractions. Conclusion This study clearly demonstrates that near-surface lake sediment pore water redox stratification and associated solid phase geochemistry vary significantly with season. This has important ramifications for seasonal changes in the bioavailability and mobility of trace elements. Without rate measurements, it is not possible to quantify the

  1. Long-term agricultural non-point source pollution loading dynamics and correlation with outlet sediment geochemistry

    NASA Astrophysics Data System (ADS)

    Ouyang, Wei; Jiao, Wei; Li, Xiaoming; Giubilato, Elisa; Critto, Andrea

    2016-09-01

    Some agricultural non-point source (NPS) pollutants accumulate in sediments in the outlet sections of watersheds. It is crucial to evaluate the historical interactions between sediment properties and watershed NPS loading. Therefore, a sediment core from the outlet of an agricultural watershed was collected. The core age was dated using the 210Pb method, and sedimentation rates were determined using the constant rate of supply (CRS) model. The total nitrogen (TN), total phosphorus (TP), Cd, Pb, Cu, Ni and Cr accumulations in the sediment generally showed fluctuating increases, with the highest sedimentation fluxes all occurring in approximately 1998. The measurement of specific mass sedimentation rates reflected a record of watershed soil erosion dynamics. Using SWAT (Soil and Water Assessment Tool) to simulate long-term watershed agricultural NPS pollution loadings, the historical interactions between sediment properties and NPS loadings were further evaluated. The N leaching process weakened these interactions, but the historical accumulations of TP and heavy metals in sediments generally correlated well with watershed NPS TP loading. The regression analysis suggested that Pb and Cr were the most suitable indexes for assessing long-term NPS TN and TP pollution, respectively. Assessing the NPS loading dynamics using the vertical characteristics of sediment geochemistry is a new method.

  2. Environmental geochemistry for surface and subsurface waters in the Pajarito Plateau and outlying areas, New Mexico

    SciTech Connect

    Blake, W.D.; Goff, F.; Adams, A.I.; Counce, D.

    1995-05-01

    This report provides background information on waters in the Los Alamos and Santa Fe regions of northern New Mexico. Specifically, the presented data include major element, trace element, and isotope analyses of 130 water samples from 94 different springs, wells, and water bodies in the area. The region considered in this study extends from the western edge of the Valles Caldera to as far east as Santa Fe Lake. For each sample, the presented analysis includes fourteen different major elements, twenty-six trace elements, up to five stable isotopes, and tritium. In addition, this data base contains certain characteristics of the water that are calculated from the aforementioned raw data, including the water`s maximum and minimum residence times, as found from tritium levels assuming no contamination, the water`s recharge elevation, as found from stable isotopes, and the charge balance of the water. The data in this report are meant to provide background information for investigations in groundwater hydrology and geochemistry, and for environmental projects. For the latter projects, the presented information would be useful for determining the presence of contamination it any one location by enabling one to compare potential contaminant levels to the background levels presented here. Likely locations of interest are those possibly effected by anthropogenic activities, including locations in and around Los Alamos National Laboratory, White Rock Canyon, and developed areas in the Rio Grande Valley.

  3. Geographic Variations in Hotspot Geochemistry Caused by 3D Dynamics and Melting of a Heterogeneous Mantle Plume

    NASA Astrophysics Data System (ADS)

    Bianco, T. A.; Ito, G.; van Hunen, J.; Ballmer, M.; Mahoney, J. J.

    2006-12-01

    Spatial variations in magma geochemistry among hotspot volcanoes hold clues to the dynamics and composition of the mantle feeding hotspot volcanism. We use a 3D geodynamic model of plume-lithosphere interaction to explore the causes of spatial patterns of magmatic volumes and compositions at intraplate hotspots. This study focuses on coupling between upper mantle flow, heat transfer, and melting of a heterogeneous (veined) plume. We assume multiple lithologies have different solidi, trace-element, and isotope composition. We use the Cartesian finite-element code, CITCOM, (Zhong and Watts, 2002) to simulate mantle convection with the extended Boussinesq approximation in a volume of upper mantle 400 km in thickness. A parameterized melting model is used to simulate melting of materials with different water contents (Katz et al., 2003). Melt depletion (F) for each lithology is calculated at finite element nodes as a function of temperature, pressure, and water content and is advected using particle tracers. We quantify the response of the geographic pattern of the volume and composition of magmas to different lithospheric thicknesses, and plume temperatures and viscosities, which together control the melting rates and sizes of the melting zones for the different lithologies. In the case of two-lithologies, preliminary results of a sluggishly convecting plume rising beneath thick lithosphere (60-100 km) predict that the melting zone of the least refractory "lithology 1" is wider than that of the more refractory "lithology 2". This leads to the prediction that on the surface, the isotope signature of lithology 1 is most prominent at the leading edge (i.e., upwind edge of plate motion) of the hotspot, whereas the isotope signature of lithology 2 is strongest at the hotspot center. This pattern will likely change for plumes convecting more vigorously or thinner lithosphere.

  4. Salt marsh pore water geochemistry does not correlate with microbial community structure

    NASA Astrophysics Data System (ADS)

    Koretsky, Carla M.; Van Cappellen, Philippe; DiChristina, Thomas J.; Kostka, Joel E.; Lowe, Kristi L.; Moore, Charles M.; Roychoudhury, Alakendra N.; Viollier, Eric

    2005-01-01

    Spatial and temporal trends in pore water geochemistry and sediment microbial community structure are compared at three intertidal sites of a saltmarsh on Sapelo Island, GA. The sites include a heavily bioturbated, unvegetated creek bank, a levee with dense growth of Spartina alterniflora, and a more sparsely vegetated ponded marsh site. The redox chemistry of the pore waters ranges from sulfide-dominated at the ponded marsh site to suboxic at the creek bank site. At the three sites, the vertical redox stratification of the pore waters is more compressed in summer than in winter. The trends in redox chemistry reflect opposing effects of sediment respiration and pore water irrigation. Intense and deep burrowing activity by fiddler crabs at the creek bank site results in the efficient oxidation of reduced byproducts of microbial metabolism and, hence, the persistence of suboxic conditions to depths of 50 cm below the sediment surface. Increased supply of labile organic substrates at the vegetated sites promotes microbial degradation processes, leading to sharper redox gradients. At the levee site, this is partly offset by the higher density and deeper penetration of roots and macrofaunal burrows. Surprisingly, the microbial community structure shows little correlation with the variable vertical redox zonation of the pore waters across the saltmarsh. At the three sites, the highest population densities of aerobic microorganisms, iron- plus manganese-reducing bacteria, and sulfate reducers coexist within the upper 10 cm of sediment. The absence of a clear vertical separation of these microorganisms is ascribed to the high supply of labile organic matter and intense mixing of the topmost sediment via bioturbation.

  5. Geochemistry of Surface and Ground Water in Cement Creek from Gladstone to Georgia Gulch and in Prospect Gulch, San Juan County, Colorado

    USGS Publications Warehouse

    Johnson, Raymond H.; Wirt, Laurie; Manning, Andrew H.; Leib, Kenneth J.; Fey, David L.; Yager, Douglas B.

    2007-01-01

    In San Juan County, Colo., the effects of historical mining continue to contribute metals to ground water and surface water. Previous research by the U.S. Geological Survey identified ground-water discharge as a significant pathway for the loading of metals to surface water in the upper Animas River watershed from both acid-mine drainage and acid-rock drainage. In support of this ground-water research effort, Prospect Gulch was selected for further study and the geochemistry of surface and ground water in the area was analyzed as part of four sampling plans: (1) ten streamflow and geochemistry measurements at five stream locations (four locations along Cement Creek plus the mouth of Prospect Gulch from July 2004 through August 2005), (2) detailed stream tracer dilution studies in Prospect Gulch and in Cement Creek from Gladstone to Georgia Gulch in early October 2004, (3) geochemistry of ground water through sampling of monitoring wells, piezometers, mine shafts, and springs, and (4) samples for noble gases and tritium/helium for recharge temperatures (recharge elevation) and ground-water age dating. This report summarizes all of the surface and ground-water data that was collected and includes: (1) all sample collection locations, (2) streamflow and geochemistry, (3) ground-water geochemistry, and (4) noble gas and tritium/helium data.

  6. Organic geochemistry and pore water chemistry of sediments from Mangrove Lake, Bermuda

    USGS Publications Warehouse

    Hatcher, P.G.; Simoneit, B.R.T.; MacKenzie, F.T.; Neumann, A.C.; Thorstenson, D.C.; Gerchakov, S.M.

    1982-01-01

    Mangrove Lake, Bermuda, is a small coastal, brackish-water lake that has accumulated 14 m of banded, gelatinous, sapropelic sediments in less than 104 yr. Stratigraphic evidence indicates that Mangrove Lake's sedimentary environment has undergone three major depositional changes (peat, freshwater gel, brackish-water gel) as a result of sea level changes. The deposits were examined geochemically in an effort to delineate sedimentological and diagenetic changes. Gas and pore water studies include measurements of sulfides, ammonia, methane, nitrogen gas, calcium, magnesium, chloride, alkalinity, and pH. Results indicate that sulfate reduction is complete, and some evidence is presented for bacterial denitrification and metal sulfide precipitation. The organic-rich sapropel is predominantly algal in origin, composed mostly of carbohydrates and insoluble macromolecular organic matter called humin with minor amounts of proteins, lipids, and humic acids. Carbohydrates and proteins undergo hydrolysis with depth in the marine sapropel but tend to be preserved in the freshwater sapropel. The humin, which has a predominantly aliphatic structure, increases linearly with depth and composes the greatest fraction of the organic matter. Humic acids are minor components and are more like polysaccharides than typical marine humic acids. Fatty acid distributions reveal that the lipids are of an algal and/or terrestrial plant source. Normal alkanes with a total concentration of 75 ppm exhibit two distribution maxima. One is centered about n-C22 with no odd/even predominance, suggestive of a degraded algal source. The other is centered at n-C31 with a distinct odd/even predominance indicative of a vascular plant origin. Stratigraphic changes in the sediment correlate to observed changes in the gas and pore water chemistry and the organic geochemistry. ?? 1982.

  7. One-carbon (bio ?) Geochemistry in Subsurface Waters of the Serpentinizing Coast Range Ophiolite

    NASA Technical Reports Server (NTRS)

    Hoehler, Tori M.; Mccollom, Tom; Schrenk, Matt; Cardace, Dawn

    2011-01-01

    Serpentinization - the aqueous alteration of ultramafic rocks - typically imparts a highly reducing and alkaline character to the reacting fluids. In turn, these can influence the speciation and potential for metabolism of one-carbon compounds in the system. We examined the aqueous geochemistry and assessed the biological potential of one-carbon compounds in the subsurface of the McLaughlin Natural Reserve (Coast Range Ophiolite, California, USA). Fluids from wells sunk at depths of 25-90 meters have pH values ranging from 9.7 to 11.5 and dissolved inorganic carbon (DIC concentrations) generally below 60 micromolar. Methane is present at concentrations up to 1.3 millimolar (approximately one-atmosphere saturation), and hydrogen concentrations are below 15 nanomolar, suggesting active consumption of H2 and production of CH4. However, methane production from CO2 is thermodynamically unfavorable under these conditions. Additionally, the speciation of DIC predominantly into carbonate at these high pH values creates a problem of carbon availability for any organisms that require CO2 (or bicarbonate) for catabolism or anabolism. A potential alternative is carbon monoxide, which is present in these waters at concentrations 2000-fold higher than equilibrium with atmospheric CO. CO is utilized in a variety of metabolisms, including methanogenesis, and bioavailability is not adversely affected by pH-dependent speciation (as for DIC). Methanogenesis from CO under in situ conditions is thermodynamically favorable and would satisfy biological energy requirements with respect to both Gibbs Energy yield and power.

  8. The Dynamics of Flowing Waters.

    ERIC Educational Resources Information Center

    Mattingly, Rosanna L.

    1987-01-01

    Describes a series of activities designed to help students understand the dynamics of flowing water. Includes investigations into determining water discharge, calculating variable velocities, utilizing flood formulas, graphing stream profiles, and learning about the water cycle. (TW)

  9. Gas Geochemistry of Ground Water in the Ilan Plain, Northeast Taiwan

    NASA Astrophysics Data System (ADS)

    Cheng, Yu-Chen; Yang, Tsanyao Frank; Chen, Ai-Ti; Fu, Ching-Chou; Lin, Shih-Jung; Liu, Tsung-Kwei; Chen, Wen-Fu; Wang, Yunshuen

    2014-05-01

    Ilan Plain is located at the northeast Taiwan and has been tectonically spreading due to the westward back-arc rifting of the Okinawa Trough. In previous studies, geological survey, geophysical research, and stratigraphic correlation were conducted to rebuild the aquifer systems in the Ilan Plain. However, few gas geochemical data of ground water are available. In this study, it is first time to systematically analyze the gas geochemistry of ground water from 37 wells to recognize the gas sources/components in the Ilan Plain. Water samples can be classified as three main groups, most samples are classified as sulfate and bicarbonate groups, few samples belong to chloride group due to the contamination of sea water. Based on the major dissolved gases compositions, the ground water samples can be divided into two groups, i.e., CH4-enriched group and N2 enriched group. Ten out of total 37 wells show CH4-enriched affinities with CH4 proportions of 30-50%, in which three wells exhibit very high CH4 contents, up to 70-90%. Two of the CH4-enriched wells are located in the northwest, and the remains are in the southeast of Ilan Plain. The dissolved radon concentrations are in the range of 800-10000 Bq/m3 in the studied area. It is interesting to note that the radon actives are higher in the west mountain areas and gradually decreasing toward the east coast areas. Meanwhile, the oxidation-reduction potential and dissolved oxygen data show positive correlations with the radon actives. It implies that the recharge of the ground water in the Ilan Plain may be from the Hsuehshan Range in west. Furthermore, elevated helium isotopic results suggest that mantle component may play an important role for the gas sources in the southeast and center of the Ilan Plain, where may be corresponding to the extensional structure or the suspected faults in the Ilan Plain. Keyword: ground water, dissolved gases, radon actives, helium isotopes, Ilan Plain

  10. Geochemistry and isotope geochemistry of the Monfalcone thermal waters (northern Italy): inference on the deep geothermal reservoir

    NASA Astrophysics Data System (ADS)

    Petrini, R.; Italiano, F.; Ponton, M.; Slejko, F. F.; Aviani, U.; Zini, L.

    2013-09-01

    Geochemical investigations were carried out to define the origin of the low- to moderate-temperature thermal waters feeding the Monfalcone springs in northern Italy. Chemical data indicate that waters approach the composition of seawater. Mixing processes with cold low-salinity waters are highlighted. The δ18O and δD values are in the range -5.0 to -6.4 ‰, and -33 to -40 ‰, respectively, suggesting the dilution of the saline reservoir by karst-type freshwaters. A surplus of Ca2+ and Sr2+ ions with respect to a conservative mixing is ascribed to diagenetic reactions of the thermal waters with Cretaceous carbonates at depth. The measured Sr isotopic composition (87Sr/86Sr ratio) ranges between 0.70803 and 0.70814; after correction for the surplus Sr, a 87Sr/86Sr ratio indicating Miocene paleo-seawater is obtained. The dissolved gases indicate long-lasting gas-water interactions with a deep-originated gas phase of crustal origin, dominated by CO2 and marked by a water TDIC isotopic composition in the range -5.9 to-8.8 and helium signature with 0.08 < R/Ra < 0.27, which is a typical range for the crust. A possible scenario for the Monfalcone thermal reservoir consists of Miocene marine paleowaters which infiltrated through the karstic voids formed within the prevalently Cretaceous carbonates during the upper Eocene emersion of the platform, and which were entrapped by the progressive burial by terrigenous sediments.

  11. Stable isotope geochemistry of pore waters from the New Jersey shelf - No evidence for Pleistocene melt water

    NASA Astrophysics Data System (ADS)

    van Geldern, Robert; Hayashi, Takeshi; Böttcher, Michael E.; Mottl, Michael J.; Barth, Johannes A. C.; Stadler, Susanne

    2013-04-01

    Ocean Drilling Program, Volume 313, Tokyo, available at: http://publications.iodp.org/proceedings/313/313toc.htm. van Geldern, R., Hayashi, T., Böttcher, M. E., Mottl, M. J., Barth, J. A. C., and Stadler, S., 2013, Stable isotope geochemistry of pore waters and marine sediments from the New Jersey shelf: Methane formation and fluid origin: Geosphere, v. 9, no. 1, p. in press.

  12. Pore water geochemistry at two seismogenic areas in the Sea of Marmara

    NASA Astrophysics Data System (ADS)

    Ruffine, Livio; Germain, Yoan; Polonia, Alina; de Prunelé, Alexis; Croguennec, Claire; Donval, Jean-Pierre; Pitel-Roudaut, Mathilde; Ponzevera, Emmanuel; Caprais, Jean-Claude; Brandily, Christophe; Grall, Céline; Bollinger, Claire; Géli, Louis; Gasperini, Luca

    2015-07-01

    Within the Sea of Marmara, the highly active North Anatolian Fault (NAF) is responsible for major earthquakes (Mw ≥ 7), and acts as a pathway for fluid migration from deep sources to the seafloor. This work reports on pore water geochemistry from three sediment cores collected in the Gulfs of Izmit and Gemlik, along the Northern and the Middle strands of the NAF, respectively. The resulting data set shows that anaerobic oxidation of methane (AOM) is the major process responsible for sulfate depletion in the shallow sediment. In the Gulf of Gemlik, depth concentration profiles of both sulfate and alkalinity exhibit a kink-type profile. The Sulfate Methane Transition Zone (SMTZ) is located at moderate depth in the area. In the Gulf of Izmit, the low concentrations observed near the seawater-sediment interface for sulfate, calcium, strontium, and magnesium result from rapid geochemical processes, AOM, and carbonate precipitation, occurring in the uppermost part of the sedimentary column and sustained by free methane accumulation. Barite dissolution and carbonate recrystallization have also been identified at deeper depth at the easternmost basin of the Gulf of Izmit. This is supported by the profile of the strontium isotope ratios (87Sr/86Sr) as a function of depth which exhibits negative anomalies compared to the modern seawater value. The strontium isotopic signature also shows that these carbonates had precipitated during the reconnection of the Sea of Marmara with the Mediterranean Sea. Finally, a first attempt to interpret the sulfate profiles observed in the light of the seismic activity at both sites is presented. We propose the hypothesis that seismic activity in the areas is responsible for the transient sulfate profile, and that the very shallow SMTZ depths observed in the Gulf of Izmit is likely due to episodic release of significant amount of methane.

  13. Geochemistry of water in aquifers and confining units of the Northern Great Plains in parts of Montana, North Dakota, South Dakota, and Wyoming

    USGS Publications Warehouse

    Busby, J.F.; Kimball, B.A.; Downey, J.S.; Peter, K.D.

    1995-01-01

    The geochemistry of water in five aquifers and two confining units in the Williston Basin of the Northern Great Plains is similar and is controlled by halite dissolution. In areas outside the Williston Basin ground-water is fresh and controlled by the solution chemistry of carbonate and sulfate minerals.

  14. Sulfur geochemistry of hydrothermal waters in Yellowstone National Park: IV Acid-sulfate waters

    USGS Publications Warehouse

    Kirk, Nordstrom D.; Blaine, McCleskey R.; Ball, J.W.

    2009-01-01

    Many waters sampled in Yellowstone National Park, both high-temperature (30-94 ??C) and low-temperature (0-30 ??C), are acid-sulfate type with pH values of 1-5. Sulfuric acid is the dominant component, especially as pH values decrease below 3, and it forms from the oxidation of elemental S whose origin is H2S in hot gases derived from boiling of hydrothermal waters at depth. Four determinations of pH were obtained: (1) field pH at field temperature, (2) laboratory pH at laboratory temperature, (3) pH based on acidity titration, and (4) pH based on charge imbalance (at both laboratory and field temperatures). Laboratory pH, charge imbalance pH (at laboratory temperature), and acidity pH were in close agreement for pH ??10%, a selection process was used to compare acidity, laboratory, and charge balance pH to arrive at the best estimate. Differences between laboratory and field pH can be explained based on Fe oxidation, H2S or S2O3 oxidation, CO2 degassing, and the temperature-dependence of pK2 for H2SO4. Charge imbalances are shown to be dependent on a speciation model for pH values 350 mg/L Cl) decrease as the Cl- concentration increases from boiling which appears inconsistent with the hypothesis of H2S oxidation as a source of hydrothermal SO4. This trend is consistent with the alternate hypothesis of anhydrite solubility equilibrium. Acid-sulfate water analyses are occasionally high in As, Hg, and NH3 concentrations but in contrast to acid mine waters they are low to below detection in Cu, Zn, Cd, and Pb concentrations. Even concentrations of SO4, Fe, and Al are much lower in thermal waters than acid mine waters of the same pH. This difference in water chemistry may explain why certain species of fly larvae live comfortably in Yellowstone's acid waters but have not been observed in acid rock drainage of the same pH.

  15. SeamountFlux: Pore water geochemistry and sediment characteristics (Guatemala Basin, East Pacific)

    NASA Astrophysics Data System (ADS)

    Pichler, T.; Poonchai, W.; Schmidt-Schierhorn, F.; Villinger, H. W.

    2011-12-01

    The scientific goal of the project "SeamountFlux" is to study a process, which can possibly contribute significantly to large scale cooling of the oceanic crust. The focus of the study is to investigate the exchange of matter and energy between the ocean and the upper young oceanic crust in the vicinity of unexplained circular depressions in the sedimentary cover, which are widely spread in the equatorial Pacific. A possible model for the formation of these so-called "hydrothermal pits" is the dissolution of calcium carbonate (CaCO3) minerals by upward flowing warm fluids, which are under-saturated in CaCO3. Seamounts are suspected to act as an entrance point for cold seawater, which then equilibrates with the basaltic oceanic crust prior to exiting through the pits. Such a process should affect the thermal structure in and around the pits as well as the geochemistry of the pore water. During cruise SO207 (June/July 2010 on the German RV Sonne) in the vicinity of ODP/IODP Site 1256 and ODP site 844 (Guatemala Basin, eastern equatorial Pacific) we collected 24 gravity cores varying in length between 3.3 m and 10.6 m from 3 distinct working areas. The cores were generally taken along a transect, starting in the center of a pit, across the pit slope to the surrounding seafloor. From these cores a total of 451 pore water samples were collected and analyzed onboard (pH, Eh, Fe, NH4 and alkalinity), as well as in the laboratory (Cl, SO4, Na, Mg, K, Ca, Sr and Mn). First results do not show any obvious evidence for the "hydrothermal" hypotheses. Pore water profiles were more or less identical, whether collected from within or from outside a pit. Chloride, SO4, Na, Mg, K, Ca, and Sr concentrations were identical to those in seawater. Particularly higher Ca and Sr concentrations were to be expected if calcium carbonate dissolution took place within the sediments. With respect to sediment composition and physico-chemical conditions in the pore waters, we observed larger

  16. Dynamics of protein hydration water

    NASA Astrophysics Data System (ADS)

    Wolf, M.; Emmert, S.; Gulich, R.; Lunkenheimer, P.; Loidl, A.

    2015-09-01

    We present the frequency- and temperature-dependent dielectric properties of lysozyme solutions in a broad concentration regime, measured at subzero temperatures, and compare the results with measurements above the freezing point of water and on hydrated lysozyme powder. Our experiments allow examining the dynamics of unfreezable hydration water in a broad temperature range. The obtained results prove the bimodality of the hydration shell dynamics. In addition, we find indications of a fragile-to-strong transition of hydration water.

  17. Dynamics of protein hydration water.

    PubMed

    Wolf, M; Emmert, S; Gulich, R; Lunkenheimer, P; Loidl, A

    2015-09-01

    We present the frequency- and temperature-dependent dielectric properties of lysozyme solutions in a broad concentration regime, measured at subzero temperatures, and compare the results with measurements above the freezing point of water and on hydrated lysozyme powder. Our experiments allow examining the dynamics of unfreezable hydration water in a broad temperature range. The obtained results prove the bimodality of the hydration shell dynamics. In addition, we find indications of a fragile-to-strong transition of hydration water. PMID:26465518

  18. Application of Hydrogen Isotope Geochemistry to Volcanology: Recent Perspective on Eruption Dynamics

    SciTech Connect

    Nakamura, M.; Kasai, Y.; Sato, N.; Yoshimura, S.

    2008-02-25

    Degassing of magma is central to understand the dynamics of volcanic eruption. Hydrogen isotopic composition of volcanic rocks reflects degassing processes. The natural obsidian samples in some eruptions typically show a gently and then rapidly decreasing {delta}D trends with decreasing water content; this led to the two-stage degassing model, with closed-system volatile exsolution (batch fractionation of hydrogen isotope) during the explosive phase followed by open-system degassing (Rayleigh fractionation) to produce the low {delta}D value of the dome and flow lavas. However, the relationship between pattern of degassing (and fractionation) and mode of eruption is controversial. Based on the CO{sub 2}/H{sub 2}O ratio of the obsidians, Rust et al. suggested that the analyzed samples with relatively constant {delta}D value and high water content were buffered (re-equilibrated) with vapor of relatively constant isotopic composition, assuming that silicic magma along conduit wall is fragmented and highly permeable. However, the timing and mechanism of the shift to open system degassing (Rayleigh fractionation) has not been clarified. To further constrain the eruption dynamics, experimental study on the hydrogen isotope fractionation during degassing would be helpful, although common noble metals used as sample capsules, including Au, are permeable to hydrogen at magmatic temperature, and even to water molecule in the prolonged run, probably due to the change of grain boundary properties such as thermal grooving.

  19. Temporal variation of trace metal geochemistry in floodplain lake sediment subject to dynamic hydrological conditions.

    PubMed

    van Griethuysen, Corine; Luitwieler, Marloes; Joziasse, Jan; Koelmans, Albert A

    2005-09-01

    Climate change and land use may significantly influence metal cycling in dynamic river systems. We studied temporal variation of sediment characteristics in a floodplain lake, including concentrations of dissolved organic carbon, acid volatile sulfide and trace metals. The sampling period included a severe winter inundation and a dramatic water level drop during summer. Temporal changes were interpreted using multivariate analysis and chemical equilibrium calculations. Metal concentrations in sediment increased with depth, indicating a gradual improvement of sediment quality. In contrast, dissolved metal concentrations were highest in top layers due to mobilization from oxyhydroxides and precipitation with sulfides in deeper layers. Inundation had a mobilizing effect as it stimulated resuspension and oxygenation of sediment top layers. Water table lowering combined with organic matter decomposition led to immobilization due to sulfide formation. The chemistry of the sediments was consistent with model calculations, especially for macro-elements. The results illustrate the importance of seasonality for metal risk assessment. PMID:15963368

  20. Maps showing water geochemistry of the Buffalo Peaks Wilderness Study Area, Lake, Park, and Chaffee Counties, Colorado

    USGS Publications Warehouse

    Nowlan, G.A.; Ficklin, Walter H.; Dover, Robert A.

    1985-01-01

    This report presents results of geochemical studies carried out in June and July of 1982 in the Buffalo Peaks Wilderness Study Area, Colo. (see index map). Samples of water were collected from 84 streams and 18 springs draining the study area. Tabulations of the analyses and a sample locality map are in Ficklin and others (1984). The geochemistry of stream sediments and panned concentrates of the study area is in Nowlan and Gerstel (1985). The geology of the study area and vicinity is in Hedlund (1985). The mineral resource potential of the study area is described in Hedlund and others (1983). This report (1) assists in the assessment of the mineral resource potential of the Buffalo Peaks Wilderness Study Area; and (2) compares analyses of water samples with analyses of stream-sediment and panned-concentrate samples (Nowlan and Gerstel, 1985).

  1. Distribution and geochemistry of contaminated subsurface waters in fissured volcanogenic bed rocks of the Lake Karachai Area, Chelyabinsk, Southern Urals

    SciTech Connect

    Solodov, I.N.; Belichkin, V.I.; Zotov, A.V.; Kochkin, B.T.; Drozhko, E.G.; Glagolev, A.V.; Skokov, A.N.

    1994-06-01

    The present investigation is devoted to the study of the distribution and geochemistry of contaminated subsurface waters, beneath the site of temporary storage of liquid radioactive waste known as Lake Karachai. For this purpose a method of hydrogeochemical logging (HGCL) together with standard hydrogeochemical and geophysical methods of uncased hole logging were used. The distribution of sodium nitrate brine plumes in the subsurface was determined by the physical and physico-chemical properties of these brines and by the petrochemical composition of enclosing rocks and the structural setting of the flow paths. The latter is represented by fractures and large faults in the bedrock of volcanogenic and volcanogenic-sedimentary rocks of intermediate-to-basic composition. The volcanogenic rocks are overlain in some places by a thin cover of unconsolidated sediments, i.e., by loams and relatively impermeable silts. Contaminated waters flow-in accordance with the eluvium bottom relief towards local areas of natural (Mishelyak and Techa rivers) and artificial (Novogomenskii water intake) discharge of subsurface waters. The large Mishelyak fault, southwest of Lake Karachai and under fluvial sediments of the Mishelyak, is assumed to significantly influence the flow pattern of contaminated waters, diverting them from an intake of drinking water.

  2. Impact of Phosphogypsum waste on the Geochemistry of the coastal water of Ghannouche -Gabes (SE of Tunisia).

    NASA Astrophysics Data System (ADS)

    Ben Amor, R.; Fathallah, S.; Gueddari, M.

    2009-04-01

    Impact of Phosphogypsum waste on the Geochemistry of the coastal water of Ghannouche -Gabes (SE of Tunisia). R. Ben Amor, S. Fathallah, M. Gueddari (R.U. of Geochemistry and of Environmental Geology, Faculty of Sciences of Tunis, Department of Geology, 2092 Manar I) Corresponding author: R. Ben Amor; E-mail:magba_rim@yahoo.fr The littoral Ghannouche - Gabes (SE of Tunisia), has been known since the 1970's, an important industrialization especially after the installation of the chemical complex for the treatment of phosphates. These industries are at the origin of various waste materials, the most significant one is phosphogypsum (PG) which is released into the sea. The aim of this paper is to identify and to analyze the different entropic and natural factors, which govern the chemical composition in major elements, dissolved oxygen, pH and temperature of Ghannouche -Gabes coastal water, while studying, in particular, the impact of PG waste on the spatial distribution of these parameters. The result of the chemical analyses of the samples taken in June 2003, show that Na, K and Cl are conserved in solution and they evolve with constant Na/Cl and K/Cl ratio. The values of these ratios are similar to sea water average. The concentration of the other elements are controlled, first, by processes of precipitation or dissolution of the carbonated (Ca, Mg and HCO3) or sulphated (Ca and SO4) minerals, and second, by dilution or evaporation phenomena and by the phosphogypsum waste. The spatial distribution of these elements, of the pH, the dissolved oxygen and the temperature and the result of the saturation index with respect to calcite, gypsum and fluorite, by using of the PhreeqC program, show that the zone, located at north of the study area, between the commercial and the fishing port, is highly influenced by the PG waste. In this area, where the PG is released and which is relatively sheltered by the dams of the commercial and fishing port, waters are characterised by

  3. Occurrence and geochemistry of radium in water from principal drinking-water aquifer systems of the United States

    USGS Publications Warehouse

    Szabo, Z.; dePaul, V.T.; Fischer, J.M.; Kraemer, T.F.; Jacobsen, E.

    2012-01-01

    competing ions Ca, Mg, Ba and Sr, and occasionally of dissolved solids, K, SO 4 and HCO 3. The other water type to frequently contain elevated concentrations of the Ra radioisotopes was acidic (low pH), and had in places, high concentrations of NO 3 and other acid anions, and on occasion, of the competing divalent cations, Mn and Al. One or the other of these broad water types was commonly present in each of the PAs in which elevated concentrations of combined Ra occurred. Concentrations of 226Ra or 228Ra or combined Ra correlated significantly with those of the above listed water-quality constituents (on the basis of the non-parametric Spearman correlation technique) and loaded on principal components describing the above water types from the entire data set and for samples from the PAs with the highest combined Ra concentrations.Concentrations of 224Ra and 226Ra were significantly correlated to those of 228Ra (Spearman's rank correlation coefficient, +0.236 and +0.326, respectively). Activity ratios of 224Ra/ 228Ra in the water samples were mostly near 1 when concentrations of both isotopes were greater than or equal to 0.037Bq/L (1pCi/L), the level above which analytical results were most reliable. Co-occurrence among these highest concentrations of the Ra radionuclides was most likely in those PAs where chemical conditions are most conducive to Ra mobility (e.g. acidic North Atlantic Coastal Plain). The concentrations of 224Ra were occasionally greater than 0.037Bq/L and the ratios of 224Ra/ 228Ra were generally highest in the PAs composed of alluvial sands and Cretaceous/Tertiary sandstones from the western USA, likely because concentrations of 224Ra are enhanced in solution relative to those of 228Ra by alpha recoil from the aquifer matrix. Rapid adsorption of the two Ra isotopes (controlled by the alkaline and oxic aquifer geochemistry) combined with preferential faster recoil of 224Ra generates a 224Ra/ 228Ra ratio much greater than

  4. Applicability of Electrical and Electroanalytical Techniques to Detect Water and Characterize the Geochemistry of Undisturbed Planetary Soils

    NASA Technical Reports Server (NTRS)

    Seshadri, S.; Buehler, M. G.; Anderson, R. C.; Kuhlman, G. M.; Keymeulen, D.; Cheung, I. W.; Schaap, M. G.

    2005-01-01

    The search for life is a primary goal of NASA s planetary exploration program. The search is, of necessity, tiered in both the detection approach (looking for evidence of microbial fossils or the presence of water in the geological history of a planetary body and/or looking for evidence of water, energy sources, precursors to life, signatures of life and/or life itself in the present day planetary environment) and in the survey method (scale, range, specificity) employed. Terrestrial investigations suggests that life as we know it requires water. Thus, the search for extant microbial life and habitats requires identifying water-bearing soils. Determining Reduction-Oxidation (REDOX) couples present in water, once it is found, provides information on soil geochemistry and identifies potential chemical energy sources for life. Mars offers a near-term target for conducting this search. The identification of gully formation [1], layered deposits [2] and elemental ratios of bromine and chlorine [3] present indirect evidence that water was abundant locally in the Martian past. Additionally, Viking images of polar ice and frost formation on the surface of Mars demonstrate that water can exist in at least some near-surface regions of present-day Mars. Atmospheric pressure data further suggest that liquid water may be stable for short periods of time in the mid-latitudes of the Martian surface. [4] Measurements of the global distribution of hydrogen in the Martian regolith offer tantalizing indirect evidence that water may at least exist in near-surface soils. [5] Evidently, any water to be found is likely to exist as soil mixtures at levels ranging between approx.0.5% and approx.5 %.

  5. Water geochemistry and hydrogeology of the shallow aquifer at Roosevelt Hot Springs, southern Utah: A hot dry rock prospect

    SciTech Connect

    Vuataz, F.D.; Goff, F.

    1987-12-01

    On the western edge of the geothermal field, three deep holes have been drilled that are very hot but mostly dry. Two of them (Phillips 9-1 and Acord 1-26 wells) have been studied by Los Alamos National Laboratory for the Hot Dry Rock (HDR) resources evaluation program. A review of data and recommendations have been formulated to evaluate the HDR geothermal potential at Roosevelt. The present report is directed toward the study of the shallow aquifer of the Milford Valley to determine if the local groundwater would be suitable for use as make-up water in an HDR system. This investigation is the result of a cooperative agreement between Los Alamos and Phillips Petroleum Co., formerly the main operator of the Roosevelt Hot Springs Unit. The presence of these hot dry wells and the similar setting of the Roosevelt area to the prototype HDR site at Fenton Hill, New Mexico, make Roosevelt a very good candidate site for creation of another HDR geothermal system. This investigation has two main objectives: to assess the water geochemistry of the valley aquifer, to determine possible problems in future make-up water use, such as scaling or corrosion in the wells and surface piping, and to assess the hydrogeology of the shallow groundwaters above the HDR zone, to characterize the physical properties of the aquifer. These two objectives are linked by the fact that the valley aquifer is naturally contaminated by geothermal fluids leaking out of the hydrothermal reservoir. In an arid region where good-quality fresh water is needed for public water supply and irrigation, nonpotable waters would be ideal for an industrial use such as injection into an HDR energy extraction system. 50 refs., 10 figs., 10 tabs.

  6. Exploration Geochemistry.

    ERIC Educational Resources Information Center

    Closs, L. Graham

    1983-01-01

    Contributions in mineral-deposit model formulation, geochemical exploration in glaciated and arid environments, analytical and sampling problems, and bibliographic research were made in symposia held and proceedings volumes published during 1982. Highlights of these symposia and proceedings and comments on trends in exploration geochemistry are…

  7. Hydrology and geochemistry of thermal ground water in southwestern Idaho and north-central Nevada

    SciTech Connect

    Young, H.W.; Lewis, R.E.

    1980-12-01

    The study area occupies about 14,500 square miles in southwestern Idaho and north-central Nevada. Thermal ground water occurs under artesian conditions, in discontinuous or compartmented zones, in igneous or sedimentary rocks of Tertiary age. Ground-water movement is generally northward. Temperatures of the ground water range from about 30/sup 0/ to more than 80/sup 0/C. Chemical analyses of water from 12 wells and 9 springs indicate that nonthermal waters are a calcium bicarbonate type; thermal waters are a sodium bicarbonate type. Chemical geothermometers indicate probable maximum reservoir temperatures are near 100/sup 0/C. Concentration of tritium in the thermal water water is near zero.

  8. The Dynamics of Supercooled Water

    NASA Astrophysics Data System (ADS)

    Mallamace, Francesco

    2011-03-01

    We present an overview of recent experiments performed on transport properties of water in the deeply supercooled region, a temperature region of fundamental importance in the science of water. We report data of nuclear magnetic resonance, quasi-elastic neutron scattering, Fourier-transform infrared spectroscopy, and Raman spectroscopy, studying water confined in nano-meter-scale environments (nano-tubes and the protein hydration water) and in bulk solutions. When contained within small pores, water does not crystallise, and can be supercooled well below its homogeneous nucleation temperature Th. On this basis it is possible to carry out a careful analysis of the well known thermodynamical anomalies of water. Studying the temperature and pressure dependencies of water dynamics, we show that the liquid-liquid phase transition (LLPT) hypothesis represents a reliable model for describing liquid water. In this model, water in the liquid state is a mixture of two different local structures, characterised by different densities, namely the low density liquid (LDL) and the high-density liquid (HDL). The LLPT line should terminate at a special transition point: a low-T liquid-liquid critical point. In particular We discuss the following experimental findings on liquid water: (i) a crossover from non-Arrhenius behaviour at high T to Arrhenius behaviour at low T in transport parameters; (ii) a breakdown of the Stokes-Einstein relation; (iii) the existence of a Widom line, which is the locus of points corresponding to maximum correlation length in the p-T phase diagram and which ends in the liquid-liquid critical point; (iv) the direct observation of the LDL phase; (v) a minimum in the density at approximately 70K below the temperature of the density maximum. In our opinion these results represent the experimental proofs of the validity of the LLPT hypothesis.

  9. Sediment Microbial Community Dynamics and Geochemistry During Oxic and Hypoxic Periods in the Gulf of Mexico

    EPA Science Inventory

    Seasonal hypoxia in the benthic waters of the Louisiana Coastal Shelf contributes to the Gulf of Mexico "dead zone" phenomena. Limited information is available on sedimentary biogeochemical interactions during periods of hypoxia.

  10. Fluid Geochemistry of the Lusi Mud Volcano (east Java, Indonesia) and Implications for Eruption Dynamics

    NASA Astrophysics Data System (ADS)

    Hartnett, H. E.; Vanderkluysen, L.; Clarke, A. B.

    2011-12-01

    The LUSI mud volcano near Sidoarjo in East Java, Indonesia, has been erupting mud and water since May 2006. It discharged as much as 180,000 cubic meters per day at the peak of its activity, destroyed thousands of homes, and displaced tens of thousands of people. The erupting fluid is a mixture of water, clays, and other minerals at near-boiling temperatures that is accompanied by venting of hot gases, primarily H2O vapor, CO2, and CH4. The LUSI mud volcano has exhibited variations in flow rate and pulsating-to-cyclic activity since the beginning of the eruption; however, there are few published geochemical studies of the system and our knowlege of the evolution of the fluid and mud composition is poor. The solids in the mud can be traced with some certainty to the blue-gray clays of the Upper Kalibeng formation, found 1600-1800 m beneath the LUSI main vent. However, the water content and chemical composition of the fluids are more difficult to interpret. An improved understanding of the fluid content and composition may provide insights that can help to constrain eruption mechanisms for this system. We have taken a multi-disciplinary approach to assess both the fluid provenance and erpution behaviour at this complex and evolving mud volcano. We present geochemical results for dissolved (major ions, trace elements, water isotopes and Sr isotopes) and solid-phased (elemental and mineralogical composition) components of not only the LUSI fluids but also of other regional fluid sources (hot springs, surface waters, sea water, and relict mud volcanoes). The LUSI fluids are compositionally distinct from all the other sources we've measured to date, including some of the older mud volcanoes, suggesting either that the underlying water source for LUSI is different, or that it has changed over time. Our major and trace element data suggest the water and solids in the LUSI fluid may not originate from the same geologic formation, providing indirect evidence in support of

  11. Combine the soil water assessment tool (SWAT) with sediment geochemistry to evaluate diffuse heavy metal loadings at watershed scale.

    PubMed

    Jiao, Wei; Ouyang, Wei; Hao, Fanghua; Huang, Haobo; Shan, Yushu; Geng, Xiaojun

    2014-09-15

    Assessing the diffuse pollutant loadings at watershed scale has become increasingly important when formulating effective watershed water management strategies, but the process was seldom achieved for heavy metals. In this study, the overall temporal-spatial variability of particulate Pb, Cu, Cr and Ni losses within an agricultural watershed was quantitatively evaluated by combining SWAT with sediment geochemistry. Results showed that the watershed particulate heavy metal loadings displayed strong variability in the simulation period 1981-2010, with an obvious increasing trend in recent years. The simulated annual average loadings were 20.21 g/ha, 21.75 g/ha, 47.35 g/ha and 21.27 g/ha for Pb, Cu, Cr and Ni, respectively. By comparison, these annual average values generally matched the estimated particulate heavy metal loadings at field scale. With spatial interpolation of field loadings, it was found that the diffuse heavy metal pollution mainly came from the sub-basins dominated with cultivated lands, accounting for over 70% of total watershed loadings. The watershed distribution of particulate heavy metal losses was very similar to that of soil loss but contrary to that of heavy metal concentrations in soil, highlighting the important role of sediment yield in controlling the diffuse heavy metal loadings. PMID:25169808

  12. Geochemistry of waters in the Valley of Ten Thousand Smokes region, Alaska

    USGS Publications Warehouse

    Keith, T.E.C.; Thompson, J.M.; Hutchinson, R.A.; White, L.D.

    1992-01-01

    Meteoric waters from cold springs and streams outside of the 1912 eruptive deposits filling the Valley of Ten Thousand Smokes (VTTS) and in the upper parts of the two major rivers draining the 1912 deposits have similar chemical trends. Thermal springs issue in the mid-valley area along a 300-m lateral section of ash-flow tuff, and range in temperature from 21 to 29.8??C in early summer and from 15 to 17??C in mid-summer. Concentrations of major and minor chemical constituents in the thermal waters are nearly identical regardless of temperature. Waters in the downvalley parts of the rivers draining the 1912 deposits are mainly mixtures of cold meteoric waters and thermal waters of which the mid-valley thermal spring waters are representative. The weathering reactions of cold waters with the 1912 deposits appear to have stabilized and add only subordinate amounts of chemical constituents to the rivers relative to those contributed by the thermal waters. Isotopic data indicate that the mid-valley thermal spring waters are meteoric, but data is inconclusive regarding the heat source. The thermal waters could be either from a shallow part of a hydrothermal system beneath the 1912 vent region or from an incompletely cooled, welded tuff lens deep in the 1912 ash-flow sheet of the upper River Lethe area. Bicarbonate-sulfate waters resulting from interaction of near-surface waters and the cooling 1953-1968 southwest Trident plug issue from thermal springs south of Katmai Pass and near Mageik Creek, although the Mageik Creek spring waters are from a well-established, more deeply circulating hydrothermal system. Katmai caldera lake waters are a result of acid gases from vigorous drowned fumaroles dissolving in lake waters composed of snowmelt and precipitation. ?? 1992.

  13. Impact of glacial/interglacial changes in water column geochemistry on the diagenetic cycling of barium in Black Sea sediments

    NASA Astrophysics Data System (ADS)

    Kasten, S.; Henkel, S.; Mogollón, J. M.; Nöthen, K.; Franke, C.; Bogus, K.; Robin, E.; Bahr, A.; Blumenberg, M.; Pape, T.; Seifert, R.; Marz, C.; De Lange, G. J.

    2012-12-01

    Changes in depositional conditions and redox environment over time affect biogeochemical processes in the seabed and in this way control the variable and selective preservation, alteration and formation of various sediment constituents and attributes - including particulate organic matter, mineral assemblages and magnetic properties. As many of these solid-phase compounds are used as paleo-environmental tracers or stratigraphic tools an assessment of diagenetic influences on the sedimentary record is crucial for accurate environmental reconstructions. We present an integrated approach of pore-water and solid-phase geochemistry as well as transport reaction modeling for sediments of the Black Sea to assess the biogeochemical history of these deposits with particular emphasis on post-depositional redistribution of barium as a consequence of changes in water column geochemistry and redox (Henkel et al., 2012). High-resolution sedimentary records of major and minor elements (Al, Ba, Ca, Sr, Ti), total organic carbon (TOC), and profiles of pore-water constituents (SO42-, CH4, Ca2+, Ba2+, Mg2+, alkalinity) were obtained for two gravity cores (core 755, 501 m water depth and core 214, 1686 m water depth) from the northwestern Black Sea. The records were examined in order to gain insight into the cycling of Ba in anoxic marine sediments characterized by a shallow sulfate-methane transition (SMT) as well as the applicability of barite as a primary productivity proxy in such a setting. The Ba records are strongly overprinted by diagenetic barite (BaSO4) remobilization and precipitation; authigenic Ba enrichments were found at both sites at and slightly above the current SMT. Transport reaction modeling was applied to simulate the migration of the SMT during the changing geochemical conditions after the Holocene seawater intrusion into the Black Sea. Based on this, sediment intervals affected by diagenetic Ba redistribution were identified. Results reveal that the intense

  14. Isotopic geochemistry of acid thermal waters and volcanic gases from Zaō volcano in Japan

    NASA Astrophysics Data System (ADS)

    Kiyosu, Yasuhiro; Kurahashi, Makoto

    1984-08-01

    The chemical composition and D/H, {18O }/{16O } and {34S }/{32S } ratios have been determined for the acid hot waters and volcanic gases discharging from Zaō volcano in Japan. The thermal springs in Zaō volcano issue acid sulfate-chloride type waters (Zaō) and acid sulfate type waters (Kamoshika). Gases emitted at Kamoshika fumaroles are rich in CO 2, SO 2 and N 2, exclusive of H 2O. Chloride concentrations and oxygen isotope data indicate that the Zaō thermal waters issue a fluid mixture from an acid thermal reservoir and meteoric waters from shallow aquifers. The waters in the Zaō volcanic system have slight isotopic shifts from the respective local meteoric values. The isotopic evidence indicates that most of the water in the system is meteoric in origin. Sulfates in Zaō acid sulfate-chloride waters with δ34S values of around +15‰, are enriched in 34S compared to Zaō H 2S, while the acid sulfate waters at Kamoshika contain supergene light sulfate ( δ 34S = ˜ + 4‰ ) derived from volcanic sulfur dioxide from the volcanic exhalations. The sulfur species in Zaō acid waters are lighter in δ34S than those of other volcanic areas, reflecting the difference in total pressure.

  15. Hydrology and geochemistry of thermal ground water in southwestern Idaho and north-central Nevada

    SciTech Connect

    Young, H.W.; Lewis, R.E.

    1982-01-01

    Chemical analyses of water from 12 wells and 9 springs indicate that nonthermal waters are a calcium bicarbonate type; thermal waters are a sodium carbonate or bicarbonate type. Chemical geothermometers indicate probable maximum reservoir temperatures are near 100/sup 0/ Celsius. Concentration of tritium in the thermal water is near zero. Depletion of stable isotopes in the hot waters relative to present-day meteoric waters indicates recharge to the system probably occurred when the climate averaged 3/sup 0/ to 5/sup 0/ Celsius colder than at present. Temperatures about 3.5/sup 0/ Celsius colder than at present occurred during periods of recorded Holocene glacial advances and indicate a residence time of water in the system of at least several thousand years. Residence time calculated on the basis of reservoir volume and thermal-water discharge is 3400 to 6800 years for an effective reservoir porosity of 0.05 and 0.10, respectively. Preliminary analyses of carbon-14 determinations indicate an age of the hot waters of about 18,000 to 25,000 years. The proposed conceptual model for the area is one of an old system, where water has circulated for thousands, even tens of thousands, of years. Within constraints imposed by the model described, reservoir thermal energy for the geothermal system in southwestern Idaho and north-central Nevada is about 130 x 10/sup 18/ calories.

  16. Ground-water quality and geochemistry in Carson and Eagle Valleys, western Nevada and eastern California

    USGS Publications Warehouse

    Welch, Alan H.

    1994-01-01

    Aquifers in Carson and Eagle Valleys are an important source of water for human consumption and agriculture. Concentrations of major constituents in water from the principal aquifers on the west sides of Carson and Eagle Valleys appear to be a result of natural geochemical reactions with minerals derived primarily from plutonic rocks. In general, water from principal aquifers is acceptable for drinking when compared with current (1993) Nevada State drinking-water maximum contaminant level standards. Water was collected and analyzed for all inorganic constituents for which primary or secondary drinking-water standards have been established. About 3 percent of these sites had con- stituents that exceeded one or more primary or secondary drinking-water standards have been established. About 3 percent of these sites had con- stituents that exceeded one or more primary standards and water at about 10 percent of the sites had at least one constituent that surpassed a secondary standard. Arsenic exceeded the standard in water at less than 1 percent of the principal aquifer sites; nitrate surpassed its standard in water at 3 percent of 93 sites. Water from wells in the principal aquifer with high concentrations of nitrate was in areas where septic systems are used; these concentrations indicate that contamination may be entering the wells. Concentrations of naturally occurring radionuclides in water from the principal aquifers, exceed the proposed Federal standards for some constituents, but were not found t be above current (1993) State standards. The uranium concen- trations exceeded the proposed 20 micrograms per liter Federal standard at 10 percent of the sites. Of the sites analyzed for all of the inorganic constituents with primary standards plus uranium, 15 percent exceed one or more established standards. If the proposed 20 micrograms per liter standard for uranium is applied to the sampled sites, then 23 percent would exceed the standard for uranium or some other

  17. Effects of slow recovery rates on water column geochemistry in aquitard wells

    USGS Publications Warehouse

    Schilling, K.E.

    2011-01-01

    Monitoring wells are often installed in aquitards to verify effectiveness for preventing migration of surface contaminants to underlying aquifers. However, water sampling of aquitard wells presents a challenge due to the slow recovery times for water recharging the wells, which can take as long as weeks, months or years to recharge depending on the sample volume needed. In this study, downhole profiling and sampling of aquitard wells was used to assess geochemical changes that occur in aquitard wells during water level recovery. Wells were sampled on three occasions spanning 11years, 1year and 1week after they were purged and casing water showed substantial water chemistry variations. Temperature decreased with depth, whereas pH and specific conductance increased with depth in the water column after 11years of water level recovery. Less stable parameters such as dissolved O2 (DO) and Eh showed strong zonation in the well column, with DO stratification occurring as the groundwater slowly entered the well. Oxidation of reduced till groundwater along with degassing of CO2 from till pore water affects mineral solubility and dissolved solid concentrations. Recommendations for sampling slowly recovering aquitard wells include identifying the zone of DO and Eh stratification in the well column and collecting water samples from below the boundary to better measure unstable geochemical parameters. ?? 2011 Elsevier Ltd.

  18. Isotope geochemistry of thermal and nonthermal waters in the Valles caldera, Jemez Mountains, northern New Mexico

    SciTech Connect

    Vuataz, F.D.; Goff, F.

    1986-02-10

    Over 100 stable isotope and 45 tritium analyses from thermal and nonthermal waters of the Jemez Mountains region, New Mexico, have been used to define the hydrodynamics of the Valles caldera (Baca) geothermal system and related geothermal fluids of the region. Evaluation of 36 cold meteoric waters yields an equation for the Jemez Mountains meteoric water line of deltaD = 8delta/sup 18/O+12, while further evaluation of nine cold meteoric waters yields an equation relating recharge elevation to deuterium content of E(meters) = -44.9 (deltaD)-1154. Based on the deuterium content of five Baca well waters (223/sup 0/--294/sup 0/C), the average recharge elevation of the Valles geothermal system ranges from 2530 to 2890 m. This range of elevations falls between the elevations of the lowest point of the caldera floor (2400 m) and the summit of the resurgent dome inside the caldera (3430 m). Thus stable isotopes indicate that the caldera depression probably serves as a recharge basin for the deep geothermal system. Although cold spring waters of the Jemez Mountains region consist of meteoric water, tritium analyses show that most of them contain water between 20 and 75 years old.

  19. The occurrence and geochemistry of fluoride in some natural waters of Kenya

    NASA Astrophysics Data System (ADS)

    Gaciri, S. J.; Davies, T. C.

    1993-03-01

    In recent years the acquisition of considerable additional data on the hydrogeochemical behaviour of fluoride in natural waters of Kenya has been made possible by extensive surface-water and groundwater sampling campaigns as well as by improvements in analytical techniques. Ultimately, the principal source of fluoride relates to emissions from volcanic activity associated with the East African Rift System. Through various intermediate steps, but also directly, fluoride passes into the natural water system and components of the food chain. Ingestion by man is mainly through drinking water and other beverages. River waters in Kenya generally have a fluoride concentration lower than the recommended level (1.3 ppm) for potable water, thus promoting susceptibility to dental caries. Groundwaters and lake waters show considerably higher fluoride contents, resulting in the widespread incidence of fluorosis in areas where groundwater is the major source of drinking water, and lake fish is a regular component of the diet. This paper presents a synthesis of the data so far obtained on the sources and distribution of fluoride in the hydrological system of Kenya, examines the extent of fluorine toxicity and puts forward recommendations to combat or minimise the problem.

  20. A Classroom Simulation of Water-Rock Interaction for Upper-Level Geochemistry Courses.

    ERIC Educational Resources Information Center

    Cercone, Karen Rose

    1988-01-01

    Describes a simple hands-on model of water-rock interaction that can be constructed in the classroom using styrofoam bowls and foil-wrapped candies. This interactive simulation allows students to vary the factors which control water-rock interaction and to obtain immediate results. (Author/CW)

  1. Mixing of hydrothermal water and groundwater near hot springs, Yellowstone National Park (USA): hydrology and geochemistry

    NASA Astrophysics Data System (ADS)

    Gibson, Matthew L.; Hinman, Nancy W.

    2013-06-01

    Studies of hot springs have focused mainly on the properties of fluids and solids. Fewer studies focus on the relationship between the hot springs and groundwater/surface-water environments. The differences in temperature and dissolved solids between hot-spring water and typical surface water and groundwater allow interactions to be traced. Electromagnetic terrain (EMT) conductivity is a nonintrusive technique capable of mapping mixing zones between distinct subsurface waters. These interactions include zones of groundwater/surface-water exchange and groundwater mixing. Herein, hydrogeological techniques are compared with EMT conductivity to trace hot-spring discharge interactions with shallow groundwater and surface water. Potentiometric-surface and water-quality data determined the hydrogeochemistry of two thermally influenced areas in Yellowstone National Park, Wyoming (USA). Data from the sites revealed EMT conductivity contrasts that reflected the infiltration of conductive hot-spring discharge to local groundwater systems. The anomalies reflect higher temperatures and conductivity for Na+-Cl--rich hydrothermal fluids compared to the receiving groundwater. EMT conductivity results suggested hot springs are fed by conduits largely isolated from shallow groundwater; mixing of waters occurs after hot-spring discharge infiltrates groundwater from the surface and, generally, not by leakage in the subsurface. A model was proposed to explain the growth of sinter mounds.

  2. Deep subsurface drip irrigation using coal-bed sodic water: part II. geochemistry

    USGS Publications Warehouse

    Bern, Carleton R.; Breit, George N.; Healy, Richard W.; Zupancic, John W.

    2013-01-01

    Waters with low salinity and high sodium adsorption ratios (SARs) present a challenge to irrigation because they degrade soil structure and infiltration capacity. In the Powder River Basin of Wyoming, such low salinity (electrical conductivity, EC 2.1 mS cm-1) and high-SAR (54) waters are co-produced with coal-bed methane and some are used for subsurface drip irrigation(SDI). The SDI system studied mixes sulfuric acid with irrigation water and applies water year-round via drip tubing buried 92 cm deep. After six years of irrigation, SAR values between 0 and 30 cm depth (0.5-1.2) are only slightly increased over non-irrigated soils (0.1-0.5). Only 8-15% of added Na has accumulated above the drip tubing. Sodicity has increased in soil surrounding the drip tubing, and geochemical simulations show that two pathways can generate sodic conditions. In soil between 45-cm depth and the drip tubing, Na from the irrigation water accumulates as evapotranspiration concentrates solutes. SAR values >12, measured by 1:1 water-soil extracts, are caused by concentration of solutes by factors up to 13. Low-EC (-1) is caused by rain and snowmelt flushing the soil and displacing ions in soil solution. Soil below the drip tubing experiences lower solute concentration factors (1-1.65) due to excess irrigation water and also contains relatively abundant native gypsum (2.4 ± 1.7 wt.%). Geochemical simulations show gypsum dissolution decreases soil-water SAR to 14 and decreasing EC in soil water to 3.2 mS cm-1. Increased sodicity in the subsurface, rather than the surface, indicates that deep SDI can be a viable means of irrigating with sodic waters.

  3. Water geochemistry of the Lucero Uplift, New Mexico: geothermal investigation of low-temperature mineralized fluids

    SciTech Connect

    Goff, F.; McCormick, T.; Gardner, J.N.; Trujillo, P.E.; Counce, D.; Vidale, R.; Charles, R.

    1983-04-01

    A detailed geochemical investigation of 27 waters of the Lucero uplift, central New Mexico, was performed to determine if the fluids originate from a high-temperature geothermal system along the Rio Grande rift. Two types of mineralized water issue from the Lucero region: a relatively saline (high-Cl, high-SO/sub 4/) type and a relatively dilute (low-Cl, high-SO/sub 4/) type. Emergence temperatures of both types range from 12 to 26/sup 0/C. Chemical data and thermodynamic and geothermometer calculations all indicate that both water types are in equilibrium with carbonate and evaporite minerals found in local Colorado Plateau rocks at surface temperatures or slightly higher. Stable isotope data do not indicate high-temperature rock-water interaction. Although evidence is seen for mixing between mineralized waters and dilute surface waters, no evidence for mixing of a deep hot fluid and surface waters is seen. Dilute mineral waters, which issue from a large area of Chinle Formation on the west side of the Lucero uplift, may be useful for low-temperature geothermal applications with appropriate design of equipment. Saline mineral waters, which leak from a zone of faulted and folded rocks along the Comanche fault zone, do not appear to have much, if any, geothermal potential due to their low-temperature, restricted distribution, and high concentration of dissolved solids. No evidence that saline mineral waters are associated with Quaternary faults of the Rio Grande rift or Quaternary basaltic volcanism within the immediate area is seen.

  4. Geochemistry for Chemists.

    ERIC Educational Resources Information Center

    Hostettler, John D.

    1985-01-01

    A geochemistry course for chemists is described. Includes: (1) general course information; (2) subject matter covered; and (3) a consideration of the uses of geochemistry in a chemistry curriculum, including geochemical "real world" examples, geochemistry in general chemistry, and geochemistry as an elective. (JN)

  5. The marine geochemistry of actinium-227: Evidence for its migration through sediment pore water

    SciTech Connect

    Nozaki, Yoshiyuki; Yamada, Masatoshi ); Nikaido, Hirofumi )

    1990-10-01

    {sup 227}Ac with a half life of 21.8 years has a potential utility as a tracer of deep water circulation and mixing studies on time scales less than 100 years. Here the authors present the first measurement of {sup 227}Ac profile in the pore water of Northwest Pacific deep-sea sediment and in the {approximately}10,000 m long water column of Izu-Ogasawara Trench. The results clearly show that {sup 227}Ac is supplied from the sediment to the overlying water through migration in the pore water. The model calculation indicates that the molecular diffusion alone through sediment porewater can support only a half of the standing crop of excess {sup 227}Ac in the water column and the enhanced supply of {sup 227}Ac by particle mixing is necessary to account for the remainder. Thus, bioturbation in the deep sea plays an important role in controlling the flux of some short-lived radionuclides such as {sup 227}Ac and {sup 228}Ra across the sediment-water interface.

  6. Radium isotope geochemistry of thermal waters, Yellowstone National Park, Wyoming, USA

    SciTech Connect

    Sturchio, N.C.; Bohlke, J.K.; Markun, F.J. )

    1993-03-01

    Radium isotope activities ([sup 226]Ra, [sup 228]Ra, and [sup 224]Ra), chemical compositions, and sulfur isotope ratios in sulfate were determined for water samples from thermal areas in Yellowstone National Park, Wyoming. Activities of [sup 226]Ra in these waters range from <0.2 to 37.9 dpm/kg. Activity ratios of [sup 228]Ra/[sup 226]Ra range from 0.26 to 14.2, and those of [sup 224]Ra/[sup 228]Ra range from 0.73 to 3.1. Radium concentrations are inversely correlated with aquifer equilibration temperatures (estimated from dissolved silica concentrations), while [Ra/Ba][sub aq] and [sup 228]Ra/[sup 226]Ra activity ratios depend upon U/Ba and Th/U ratios in aquifer rocks. Major controls on Ra concentration in Yellowstone thermal waters are inferred to be (1) barite saturation (at Norris Geyser Basin, Mammoth Hot Springs, and other northern areas) and (2) zeolite-water ion exchange (at Upper Geyser Basin). The data are consistent with a model in which (1) radium and barium are supplied to water by bulk dissolution of aquifer rock, and (2) chemical equilibration of water with rock is rapid relative to the 1602 year half-life of [sup 226]Ra. The [sup 228]Ra/[sup 226]Ra activity ratios of the waters may in some cases reflect surface enrichments of [sup 232]Th and/or may indicate that [alpha]-recoil input of [sup 228]Ra is rapid relative to water-rock chemical equilibration. Activity ratios of [sup 224]Ra/[sup 228]Ra indicate a nearly ubiquitous [sup 224]Ra excess that generally increases with decreasing pH. Near-surface ([le]100 m) thermal water flow velocities at Mammoth Hot Springs are estimated from [sup 224]Ra/[sup 228]Ra variation to be [ge]1 m h[sup [minus]1]. 73 refs., 4 figs., 4 tabs.

  7. Arsenic in ground water of the United States: occurrence and geochemistry

    USGS Publications Warehouse

    Welch, Alan H.; Westjohn, D.B.; Helsel, Dennis R.; Wanty, Richard B.

    2000-01-01

    Concentrations of naturally occurring arsenic in ground water vary regionally due to a combination of climate and geology. Although slightly less than half of 30,000 arsenic analyses of ground water in the United States were ≤ 1 µg/L, about 10% exceeded 0 µg/L. At a broad regional scale, arsenic concentrations exceeding 10 µg/L appear to be more frequently observed in the western United States than in the eastern half. Arsenic concentrations in ground water of the Appalachian Highlands and the Atlantic plain generally are very low (≤ 1 µg/L). Concentrations are somewhat greater in the Interior Plains and the Rocky Mountain System, investigations of ground water in New England, Michigan, Minnesota, South Dakota, Oklahoma, and Wisconsin within the last decade suggest that arsenic concentrations exceeding 10 µg/L are more widespread and common than previously recognized. Arsenic release from iron oxide appears to be the most common cause of widespread arsenic concentrations exceeding 10 µg/L a ground water. This can occur in response to different geochemical conditions, including release of arsenic to ground water through reaction of iron oxide with either natural or anthropogenic (i.e., petroleum products) organic carbon. Iron oxide also can release arsenic to alkaline ground water, such as that found in some felsic volcanic rocks and alkaline aquifers of the Western United States. Sulfide minerals are both a source and sink for arsenic. Geothermal water and high evaporation rates also are associated with arsenic concentrations ≥ 10g/L in ground and surface water, particularly in the west.

  8. Hydro geochemistry Study of Yamama formation water in southern Iraqi oil Fields, Migration,Diagensis

    NASA Astrophysics Data System (ADS)

    Ali, A. A.; SOC Team

    2013-05-01

    Yamama Formation (Lower Cretaceous) form one of the main oil reservoir in southern Iraq, the present study deals with the general physical and chemical characteristics of Yamama formation water in selected oil fields - southern Iraq. Via the collecting the available water analysis data in in selected 10 wells in southern Iraqi oil fields, Well Logs, as well as, the technical final well reports. The task of this study is to illustrate the chemical and physical variation among the study oil wells, and their relation with the depositional environment, the grading of temperature and pressure, the reason behind of over pressure phenomenon, besides the delineation of oil migration and water reservoir movement direction. The study confirms the occurrences of two types of formation water; the first one is the connate water, which is brine, hypersaline, and marine in nature reflects the possibility of hydrocarbon accumulations. And the second is mixing water reflects the mixing of original marine water with percolating meteoric water for various degree. Regarding the hydrochemical ratios, the direction of water movement and oil migration is from northeast toward west and south west starting from Messan oil Fields, moreover, the secondary migration of oil is in the same direction. The western migration of oil and water attributed to the enhancement of porosity and permeability in this direction, which in turn means the possibility of finding new stratigraphic traps in this direction mainly western of Nasiriya and Garraf areas. The relationship between depositional environment and diagenetic processes in one hand, and the sediment logical units; tidal lime granular unit revealed the occurrences of khidar al-may which extends up to Al-Managish in Kuwait and Nahar Umar - Majnoon, Nasiriya - Abu Amood, as well as the clayey units represented by isolated and semi isolated lagoonal deposits. Based on the ionic ratios in AlZubair, Nahar Umer and Al-Kifil oil fields, outer shelf

  9. Rare earth element geochemistry in cold-seep pore waters of Hydrate Ridge, northeast Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Himmler, Tobias; Haley, Brian A.; Torres, Marta E.; Klinkhammer, Gary P.; Bohrmann, Gerhard; Peckmann, Jörn

    2013-07-01

    The concentrations of rare earth elements (REEs), sulphate, hydrogen sulphide, total alkalinity, calcium, magnesium and phosphate were measured in shallow (<12 cm below seafloor) pore waters from cold-seep sediments on the northern and southern summits of Hydrate Ridge, offshore Oregon. Downward-decreasing sulphate and coevally increasing sulphide concentrations reveal sulphate reduction as dominant early diagenetic process from ~2 cm depth downwards. A strong increase of total dissolved REE (∑REE) concentrations is evident immediately below the sediment-water interface, which can be related to early diagenetic release of REEs into pore water resulting from the re-mineralization of particulate organic matter. The highest pore water ∑REE concentrations were measured close to the sediment-water interface at ~2 cm depth. Distinct shale-normalized REE patterns point to particulate organic matter and iron oxides as main REE sources in the upper ~2-cm depth interval. In general, the pore waters have shale-normalized patterns reflecting heavy REE (HREE) enrichment, which suggests preferential complexation of HREEs with carbonate ions. Below ~2 cm depth, a downward decrease in ∑REE correlates with a decrease in pore water calcium concentrations. At this depth, the anaerobic oxidation of methane (AOM) coupled to sulphate reduction increases carbonate alkalinity through the production of bicarbonate, which results in the precipitation of carbonate minerals. It seems therefore likely that the REEs and calcium are consumed during vast AOM-induced precipitation of carbonate in shallow Hydrate Ridge sediments. The analysis of pore waters from Hydrate Ridge shed new light on early diagenetic processes at cold seeps, corroborating the great potential of REEs to identify geochemical processes and to constrain environmental conditions.

  10. Seasonal nutrient dynamics in the Anacostia River (D.C., USA): geochemistry and hydrocarbon biomarkers

    NASA Astrophysics Data System (ADS)

    Sarraino, S.; Frantz, D. E.; Macavoy, S. E.

    2010-12-01

    The seasonal biogeochemistry of the urban Anacostia River (Washington D.C. USA) was investigated. Chemical parameters examined include: inorganics (Ca, Mg, Na, S, K, P, NO3, NH4, PO4, B, Ba, Ni, Co); fatty acids and other hydrocarbons; C, N and S stable isotopes; and other water chemistry indicators (hardness, salinity, alkalinity, soluble salts, SAR, TDS). Between April and July 2010, water and sediment were sampled from three tidal freshwater sites along the Anacostia River (UP, MID, and DWN). Two of the selected sites, UP and DWN, are located next to a combined sewage outflow. Water column nutrient analysis shows increasing availability of ammonium (NH4) and nitrate (NO3) at all sites between April and July. At MID, the site showing the highest rates of nutrient growth over the sampling period, NH4 concentrations increase from 0.13 to 1.49 µg/L and NO3 concentrations increase from 0.71 to 2.88 mg/L. A marked NO3 pulse is observed at the DWN site in early May; NO3 concentrations jump from 0.68 to 3.36 mg/L between April 5 and May 6, decreasing to 1.22 mg/L by May 20. Unlike UP and MID, which show NH4 and NO3 increasing concurrently, this NO3 pulse at DWN is accompanied with a decline in NH4 levels, suggestive of an allochthonous NO3 source. Forthcoming stable isotope data are expected to characterize the source of such nitrogen inputs, as well as organic material, throughout the year. Preliminary GC-MS analysis of isolated fatty acids does not explicitly suggest bacterial or higher plant dominance in the spring; however, some notable compounds were identified, such as the PAH fluoranthene, naphthoquinone, and testosterone, as well as a number of cholesterols and other steroids. Higher proportions of bacterial fatty acid biomarkers are expected during the summer. Principle Component Analysis (PCA) of the chemistry data suggests geochemical variables, rather than nutrients, are the driving forces of observed trends. PCA, along with fatty acid characterization and

  11. Change in Magma Dynamics at Okataina Rhyolite Caldera revealed by Plagioclase Textures and Geochemistry

    NASA Astrophysics Data System (ADS)

    Shane, P. A. R.

    2015-12-01

    A fundamental reorganization of magma dynamics at Okataina volcano, New Zealand, occurred at 26 ka involving a change from smaller volume, high-temperature rhyodacite magmas to a lower eruptive tempo of larger volume, low-temperature, rhyolite magmas. Zircon studies demonstrate the presence of a periodically active, long-lived (100,000 yr) magmatic reservoir. However, there is little correlation between periods of zircon crystallization and eruption events. In contrast, the changing magmatic dynamics is revealed in plagioclase growth histories. Crystals from the ~0.7 ka Kaharoa eruption are characterized by resorbed cores displaying a cellular-texture of high-An (>40) zones partially replaced by low-An (<30) zones, surrounded by a resorption surface and a prominent normal-zoned rim (An50-20). Elevated An, Fe, Mg, Sr and Ti follow the resorption surface and display rimward depletion trends, accompanied by Ba and REE enrichment. The zonation is consistent with fractional crystallization and cooling. The cores display wide trace element diversity, pointing to crystallization in a variety of melts, before transport and mixing into a common magma where the rims grew. Plagioclase from the ~36 ka Hauparu eruption display several regrowth zones separated by resorption surfaces, which surround small resorbed cores with a spongy cellular texture of variable An content (An 40-50). The crystals display step-wise re-growth of successively higher An, Fe, Mg and Ti content, consistent with progressive mafic recharge. Two crystal groups are distinguished by trace element chemistry indicating growth in separate melts and co-occurrence via magma-mingling. The contrasting zoning patterns in plagioclase correspond to the evolutionary history of magmatism at Okataina. Emptying of the magma reservoir following caldera eruption at 46 ka reduced barriers to mafic magma ascent. This is recorded by the frequent resorption and recharge episodes in Hauparu crystals. Subsequent re

  12. Ground-water quality and geochemistry in Dayton, Stagecoach, and Churchill Valleys, western Nevada

    USGS Publications Warehouse

    Thomas, James M.; Lawrence, Stephen J.

    1994-01-01

    The U.S. Geological Survey investigated the quality of ground water in the Dayton, Stagecoach, and Churchill Valleys as part of the Carson River Basin National Water-Quality Assessment (NAWQA) pilot study. Four aquifer systems have been de- lineated in the study area. Principal aquifers are unconsolidated deposits at altitudes of less than 4,900 feet above sea level and more than 50 feet below land surface. Shallow aquifers are at altitudes of less than 4,900 feet and less than 50 feet below land surface. Upland aquifers are above 4,900 feet and provide recharge to the principal aquifers. Thermal aquifers, defined as those having a water temperature greater than 30 degrees Celsius, are also present. Ground water used in Dayton, Stagecoach, and Churchill Valleys is pumped from principal aquifers in unconsolidated basin-fill deposits. Ground water in these aquifers originates as precipitation in the adjacent mountains and is recharged by the Carson River and by underflow from adjacent upstream valleys. Ground-water flow is generally parallel to the direction of surface-water flow in the Carson River. Ground water is discharged by pumping, evapo- transpiration, and underflow into the Carson River. The results of geochemical modeling indicate that as ground water moves from upland aquifers in mountainous recharge areas to principal aquifers in basin-fill deposits, the following processes probably occur: (1) plagioclase feldspar, sodium chloride, gypsum (or pyrite), potassium feldspar, and biotite dissolve; (2) calcite precipitates; (3) kaolinite forms; (4) small amounts of calcium and magnesium in the water exchange for potassium on aquifer minerals; and (5) carbon dioxide is gained or lost. The geochemical models are consistent with (1) phases identified in basin- fill sediments; (2) chemical activity of major cations and silica; (3) saturation indices of calcite and amorphous silica; (4) phase relations for aluminosilicate minerals indicated by activity diagrams; and

  13. Hydrogeophysics and geochemistry reveal heterogeneity and water quality improvements in aquifer recharge and recovery (ARR) (Invited)

    NASA Astrophysics Data System (ADS)

    Parsekian, A.; Regnery, J.; Wing, A.; Knight, R. J.; Drewes, J. E.

    2013-12-01

    Aquifer recharge and recover (ARR) is the process of infiltrating water into the ground for storage and withdrawal through wells at a later time. Two significant challenges faced during the design of ARR systems are 1) evaluating aquifer heterogeneity and 2) understanding the rock fluid interactions; these knowledge gaps may have profound impacts on the volume of recoverable water and the improvement in water quality in comparison with the source-water. Our objective in this research is to leverage the advantages of hydrogeophysical measurements and geochemical sampling to reveal the properties of an aquifer through which ARR water travels with the goal of informing current operations and future design decisions. Combined geophysical and geochemical investigations reveal subsurface heterogeneity, indicate possible flow paths though the aquifer and quantify specific reductions in contaminant concentrations. Ground penetrating radar (GPR), electromagnetic induction (EMI) and electrical resistivity tomography (ERT) were used to image the subsurface throughout two key infiltration/extraction areas of an ARR site in Colorado, USA. The most valuable results came from 2.5D ERT revealing the structural patterns and suggesting the distribution of textural composition of unconsolidated sediments. Geochemical measurements on transects intersecting the geophysical measurements resolved bulk parameters (i.e. total organic carbon, cations, anions) and trace organic contaminants (e.g. trace organic compounds) and were also used to estimate mixing and water travel times and assess the performance of the ARR site regarding water quality and quantity. Our results indicate that the subsurface is highly heterogeneous at our study site and that the coarse-grained sedimentary units, acting as the best conduit for transporting water, are likely discontinuous. The electrical resistivity measurements indicate certain areas of the infiltration basins may have good hydraulic connections to

  14. Isotope geochemistry of waters affected by acid mine drainage in old labour sites (SE, Spain).

    NASA Astrophysics Data System (ADS)

    Pérez-Sirvent, Carmen; Martinez-Sanchez, Maria Jose; Garcia-Lorenzo, Maria Luz; Agudo, Ines; Hernandez-Cordoba, Manuel; Recio, Clemente

    2015-04-01

    The ore deposits of this zone have iron, lead and zinc as the main metal components. Iron is present in oxides, hydroxides, sulfides, sulfates, carbonates, and silicates; lead and zinc occur in sulfides (galena and sphalerite, respectively), carbonates, sulfates, and lead or zinc-bearing (manganese, iron) oxides. Mining started with the Romans and activity peaked in the second half of the 19th century and throughout the 20th century until the 1980's. From 1940 to 1957, mineral concentration was made by froth flotation and, prior to this, by gravimetric techniques. The mining wastes, or tailings, with a very fine particle size were deposited inland (tailings dams) and, since 1957, huge releases were made in directly the sea coast. The objective of this work was to evaluate processes affecting waters from abandoned mine sites by way of stable isotopic analysis, particularly H and O stable isotopes from water and S and O from dissolved sulfates. Several common chemical and physical processes, such as evaporation, water-rock interaction and mixing could alter water isotopic composition. Evaporation, which causes an enrichment in δD and δ18O in the residual water, is an important process in semiarid areas. The results obtained indicate that, for sites near the coast, waters are meteoric, and marine infiltration only takes place in the deepest layers near the shore or if water remains stagnated in sediments with low permeability. The main source of sulfate was the oxidation of sulfides, resulting in the liberation of acid, sulfate and metals. In order to assess the mechanism responsible for sulfide oxidation, the stoichiometric isotope balance model and the general isotope balance model were tested, suggesting that the oxidation via Fe3+ was predominant in the surface, and controlled by A. ferrooxidans, while at depth, sulfate reduction occurred.

  15. Heterogeneities in ground-water geochemistry in a sand aquifer beneath an irrigated field

    NASA Astrophysics Data System (ADS)

    Kelly, Walton R.

    1997-11-01

    The contamination of shallow aquifers by elevated nitrate concentrations is a common problem in many rural regions of the world. Aquifers under irrigated land are especially susceptible to this type of contamination. An intensive three-dimensional investigation of water chemistry was undertaken in a shallow unconfined sand aquifer in an area of intensive irrigation in Mason County, Illinois, in order to investigate processes affecting water quality. Results reveal considerable heterogeneity in the aqueous chemistry in three spatial dimensions and temporally. Recharge is rapid in this system and the water chemistry of the recharge water is variable both spatially and temporally, being especially influenced by agricultural practices. Nitrate concentrations are elevated in a zone between about 6 and 10 m beneath the surface, although in certain areas and at certain times this zone was not found. The maximum nitrate concentrations in this zone were slightly greater than 20 mg l -1 as N, well above the US Environmental Protection Agency's maximum contaminant level (MCL) of 10 mg l -1. Nitrate was generally absent both above and below this depth in the aquifer. Water relatively depleted in nitrate recharges the aquifer from the surface at the site, producing a zone of dilute water near the water table. Beneath the plume, denitrification reactions are responsible for removing nitrate from solution, probably mainly coupled to oxidation of sulfide minerals; tritium data suggest that vertical movement of solutes is rapid and thus there has been enough time to transport surface-applied fertilizer to depths in excess of 30 m in the aquifer. This rapid vertical movement is almost certainly enhanced by intensive irrigation in the county. A number of aqueous species and chemical parameters (Ca, Mg, Sr, Fe, Si, dissolved inorganic carbon (DIC), dissolved oxygen, total dissolved solids, and pH) are correlated with nitrate concentrations, primarily because, like nitrate, they are

  16. Cryptic Role of Zero-Valent Sulfur in Metal and Metalloid Geochemistry in Euxinic Waters

    NASA Astrophysics Data System (ADS)

    Helz, G. R.

    2014-12-01

    Natural waters that are isolated from the atmosphere in confined aquifers, euxinic basins and sediment pore waters often become sulfidic. These waters are conventionally described simply as reducing environments. But because nature does not constrain their exposure to reducing equivalents (e.g. from organic matter) and oxidizing equivalents (e.g. from Fe,Mn oxides), these reducing environments in fact vary cryptically in their redox characteristics. The implications for trace metal and metalloid cycles are only beginning to be explored. The activity of zero-valent sulfur (aS0), a virtual thermodynamic property, is a potentially useful index for describing this variation. At a particular temperature and ionic strength, aS0 can be quantified from knowledge of pH and the total S(0) to total S(-II) ratio. Although data are incomplete, the deep waters of the Black Sea (aS0 ca. 0.3) appear to be more reducing than the deep waters of the Cariaco Basin (aS0 ca. 0.5) even though both are perennially sulfidic. An apparent manifestation is a greater preponderance of greigite relative to mackinawite in the Cariaco Basin. Interestingly, greigite is stable relative to mackinawite in both basins but predominates only at the higher aS0. Values of aS0 in sulfidic natural waters span the range over which Hg-polysulfide complexes gain predominance over Hg sulfide complexes. Competition between these ligands is thought to influence biological methylation, mercury's route into aquatic and human food chains. In sulfidic deep ground waters, the redox state and consequent mobility of As, a global human hazard, will depend on aS0. At intermediate sulfide concentrations, higher aS0 favors more highly charged and thus less mobile As(V) species relative to As(III) species despite the overall reducing characteristics of such waters. Helz, G.R. (2014) Activity of zero-valent sulfur in sulfidic natural waters. Geochem. Trans. In press.

  17. Pore Water Geochemistry of IODP Exp 315 and 316: The NanTroSEIZE Transect

    NASA Astrophysics Data System (ADS)

    Wheat, C. G.; Hulme, S.; Tomaru, H.; Liljedahl, L. C.; Solomon, E.

    2008-12-01

    IODP Exp 315 and 316 drilled six sites as part of the first stage of NanTroSEIZE, an international, multi-year endeavor to elucidate earthquake-related processes. These six sites form a transect southeast of the Kumano Basin, Japan with boreholes that penetrated the Kumano forarc basin (C0002), the megasplay fault region (C0001, C0004, and C0008) and the frontal thrust including sediment from the subducting plate (C0006 and C0007). One element of this drilling is to evaluate the relationship between pore fluid behavior and slip and deformation in the crust. To help address this relationship 322 pore water samples were extracted from sediment whole rounds. Each of the whole rounds was scanned (CT) before it was processed within a nitrogen-filled glove bag and squeezed to express the pore fluid. In addition, 15 samples from C0002 underwent the GRIND technique to gather baseline pore water chemical data for future deep drilling where highly indurated sediments likely exist. Each of these pore water samples underwent a range of analytical procedures at sea. Additional procedures were conducted ashore. Combined, these procedures resulted in data for 30 chemical species including the stable isotopic composition of O and H in water. These data provide the most thorough preliminary reports tables in the history of DSDP, ODP and IODP, and ongoing measurements include a range of isotopic (e.g., I, B, Sr, Li, C), ionic (e.g., REE), and organic measurements. We will present all of the data that appear in the preliminary reports including GRIND samples for comparison to squeezed samples. Our presentation will highlight changes in pore water composition along the transect of boreholes, putting individual site-related pore water chemical profiles in a broader context. Pore water profiles in the upper about 30 m of the sediment column are dominated by microbially mediated reactions with a highly defined sulfate-methane transition. Deeper within the sediment the dissociation of gas

  18. Effects of acid mine effluent on sediment and water geochemistry, Ruttan Cu-Zn mine

    USGS Publications Warehouse

    Shilts, W.W.

    1996-01-01

    Waters were collected from the surface and bottom of four lakes as well as from the Churchill River and approximately 20 small ponds beside the Leaf Rapids-Ruttan mine-South Indian Lake road to determine geochemical variations related to tailings and waste rock disposal from the Ruttan Cu-Zn VHMS deposit. Using sonar profiling as a guide, grab samples and cores of sediments were also collected in Ruttan, Brehaut, Rusty, and Alto lakes to investigate the geochemical and sedimentological effects of liming the acid (pH 2.5) outflow from Ruttan Lake. Preliminary results indicate that metals anthropogenically enriched in Ruttan Lake (Zn, Cd, and Hg in particular) are scavenged and precipitated at the inflow end of Brehaut Lake as a result of adding lime solutions to the Vermilion River, midway through the 500 m reach that connects Ruttan Lake and Brehaut Lake. Zn in Ruttan Lake water (up to 17 ppm) is precipitated in the limey sediment. Zn is not enriched in waters of Rusty Lake, the next lake downstream from Brehaut Lake. Rusty Lake has Zn concentrations comparable to background water from Alto Lake (<10 ppb Zn). At present, liming appears to be controlling metal migration effectively, but a body of Zn-Cd-Hg-rich carbonate precipitate occupies the south end of Brehaut Lake which, without liming, would be receiving water of pH 2.5 from Ruttan Lake, resulting in a remobilization of metals. The related study also showed that Zn concentrations are elevated in water in contact with waste rock used to upgrade sections of the Leaf Rapids-South Indian Lake and Brehaut Lake roads.

  19. Implications of formation water movement based on isotopic data and elemental geochemistry, southwestern Ontario

    SciTech Connect

    Frape, S.K.; Dollar, P.; Fritz, P.; Travail, R.A.; McNutt, R.H.; MacQueen, R.W.

    1986-08-01

    Formation waters in Paleozoic sediments analyzed for /sup 2/H, /sup 18/O, /sup 87/Sr//sup 86/Sr, tritium, and major/minor contents show the following. (1) The stable isotope contents are typical for formation brines, but have /sup 18/O and /sup 2/H values that group according to formation age, with waters in Cambrian strata being most depleted; and the most concentrated brines do not compare well to known Michigan basin brines. Many waters are Ca-Na-Cl brines similar to typical Canadian shield brines, although the origin of the various chemical species may be masked by intense rock-water interaction. (2) The /sup 87/Sr//sup 86/Sr values for Cambrian brines range from 0.7095 to 0.7102. In one detailed study, the brine and calcite cement had the same value (0.7095), which is slightly higher than Cambrian seawater (0.7091-0.7092), and indicates that the cement precipitated from the brine during diagenesis. The reservoir rock has a /sup 87/Sr//sup 86/Sr value of 0.7330, indicating little or no water/rock exchange. Sr isotopic values for Ordovician brines range from 0.7095 to 0.7103, which is higher than Ordovician seawater (0.7085). In contrast, the Silurian Salina Formation brines and Silurian seawater values are the same (0.7085-0.7087). Despite an active tectonic history, causing considerable faulting and movement within Paleozoic and Precambrian rock strata, the isotopic results for the Cambrian indicate isotopic equilibrium between brine and cement; therefore, these formation waters have not moved since the calcite formed.

  20. Ground-Water Geochemistry of Kwajalein Island, Republic of the Marshall Islands, 1991

    USGS Publications Warehouse

    Tribble, Gordon W.

    1997-01-01

    Ground water on Kwajalein Island is an important source of drinking water, particularly during periods of low rainfall. Fresh ground water is found as a thin lens underlain by saltwater. The concentration of dissolved ions increases with depth below the water table and proximity to the shoreline as high-salinity seawater mixes with fresh ground water. The maximum depth of the freshwater lens is 37 ft. Chloride is assumed to be non-reactive under the range of geochemical conditions on the atoll. The concentration of chloride thus is used as a conservative constituent to evaluate freshwater-saltwater mixing within the aquifer. Concentrations of sodium and for the most part, potassium and sulfate, also appear to be determined by conservative mixing between saltwater and rain. Concentrations of calcium, magnesium, and strontium are higher than expected from conservative mixing; these higher concentrations are a result of the dissolution of carbonate minerals. An excess in dissolved inorganic carbon results from carbonate-mineral dissolution and from the oxidation of organic matter in the aquifer; the stoichiometric difference between excess dissolved inorganic carbon and excess bivalent cations is used as a measure of the amount of organic-matter oxidation. Organic-matter oxidation also is indicated by the low concentration of dissolved oxygen, high concentrations of nutrients, and the presence of hydrogen sulfide in many of the water samples. Low levels of dissolved oxygen indicate oxic respiration, and sulfate reduction is indicated by hydrogen sulfide. The amount of dissolved inorganic carbon released during organic-matter oxidation is nearly equivalent to the amount of carbonate-mineral dissolution. Organic-matter oxidation and carbonate-mineral dissolution seem to be most active either in the unsaturated zone or near the top of the water table. The most plausible explanation is that high amounts of oxic respiration in the unsaturated zone generate carbon dioxide

  1. Water-rock interaction and geochemistry of groundwater from the Ain Azel aquifer, Algeria.

    PubMed

    Belkhiri, Lazhar; Mouni, Lotfi; Tiri, Ammar

    2012-02-01

    Hydrochemical, multivariate statistical, and inverse geochemical modeling techniques were used to investigate the hydrochemical evolution within the Ain Azel aquifer, Algeria. Cluster analysis based on major ion contents defined 3 main chemical water types, reflecting different hydrochemical processes. The first group water, group 1, has low salinity (mean EC = 735 μS/cm). The second group waters are classified as Cl-HCO(3)-alkaline earth type. The third group is made up of water samples, the cation composition of which is dominated by Ca and Mg with anion composition varying from dominantly Cl to dominantly HCO(3) plus SO(4). The varifactors obtained from R-mode FA indicate that the parameters responsible for groundwater quality variations are mainly related to the presence and dissolution of some carbonate, silicate, and evaporite minerals in the aquifer. Inverse geochemical modeling along groundwater flow paths indicates the dominant processes are the consumption of CO(2), the dissolution of dolomite, gypsum, and halite, along with the precipitation of calcite, Ca-montmorillonite, illite, kaolinite, and quartz. PMID:21336647

  2. Geochemistry and quality parameters of dug and tube well water of Khipro, District Sanghar, Sindh, Pakistan

    NASA Astrophysics Data System (ADS)

    Bashir, Erum; Huda, Syed Nawaz-ul; Naseem, Shahid; Hamza, Salma; Kaleem, Maria

    2015-08-01

    Thirty-nine (23 dug and 16 tube well) samples were geochemically evaluated and investigated to ascertain the quality of water in Khipro, Sindh. The analytical results exhibited abundance of major cations and anions in Na+ > Ca2+ > Mg2+ > K+ and Cl- > HCO3 - > SO4 2- sequence. Stiff diagram showed dug well sample have high Na-Cl and moderate Mg-SO4 content as compared to tube well samples. Majority of dug well samples appeared as Na-Cl type on Piper diagram while tube well samples are mixed type. Gibbs diagram reflected evaporation as a dominant phenomenon in dug well; however, tube well samples are declined toward rock dominance. Process of ion exchange was witnessed from Na+ versus Cl- and Ca2+ + Mg2+ versus HCO3 - + SO4 2- plots. Principal component analysis also discriminates dug well and tube well water by means of positive and negative loading based on physical and chemical composition of the groundwater. Studied and computed parameters like pH, EC, TDS, TH, Na+, K+, Ca2+, Mg2+, Cl-, SO4 2-, HCO3 -, sodium adsorption ratio, magnesium adsorption ratio, potential salinity, residual sodium carbonate, Na%, Kelly's ratio, and permeability index were compared with WHO to evaluate studied water for drinking and agricultural purposes. Except Na+ and K+, all chemical constrains are within the allowed limits, set by WHO for drinking water. Similarly, most of the groundwater is moderately suitable for irrigation uses, with few exceptions.

  3. Geochemistry and source waters of rock glacier outflow, Colorado Front Range

    USGS Publications Warehouse

    Williams, M.W.; Knauf, M.; Caine, N.; Liu, F.; Verplanck, P.L.

    2006-01-01

    We characterize the seasonal variation in the geochemical and isotopic content of the outflow of the Green Lake 5 rock glacier (RG5), located in the Green Lakes Valley of the Colorado Front Range, USA. Between June and August, the geochemical content of rock glacier outflow does not appear to differ substantially from that of other surface waters in the Green Lakes Valley. Thus, for this alpine ecosystem at this time of year there does not appear to be large differences in water quality among rock glacier outflow, glacier and blockslope discharge, and discharge from small alpine catchments. However, in September concentrations of Mg2+ in the outflow of the rock glacier increased to more than 900 ??eq L-1 compared to values of less than 40 ??eq L-1 at all the other sites, concentrations of Ca2+ were greater than 4,000 ??eq L-1 compared to maximum values of less than 200 ??eq L-1 at all other sites, and concentrations of SO42- reached 7,000 ??eq L-1, compared to maximum concentrations below 120 ??eq L-1 at the other sites. Inverse geochemical modelling suggests that dissolution of pyrite, epidote, chlorite and minor calcite as well as the precipitation of silica and goethite best explain these elevated concentrations of solutes in the outflow of the rock glacier. Three component hydrograph separation using end-member mixing analysis shows that melted snow comprised an average of 30% of RG5 outflow, soil water 32%, and base flow 38%. Snow was the dominant source water in June, soil water was the dominant water source in July, and base flow was the dominant source in September. Enrichment of ?? 18O from - 10??? in the outflow of the rock glacier compared to -20??? in snow and enrichment of deuterium excess from +17.5??? in rock glacier outflow compared to +11??? in snow, suggests that melt of internal ice that had undergone multiple melt/freeze episodes was the dominant source of base flow. Copyright ?? 2005 John Wiley & Sons, Ltd.

  4. Geochemistry and Hydrogeology of Water-Filled Sinkholes at Bitter Lake NWR, Roswell, NM

    NASA Astrophysics Data System (ADS)

    Premo, Z. E.; Crossey, L. J.

    2008-12-01

    Bitter Lake NWR in southeast (Roswell) New Mexico is located at the convergence of the Pecos River and the surface discharge region in the Roswell Artesian Basin (shallow alluvial aquifer and carbonate aquifer). The Refuge hosts approximately 50 water-filled sinkholes, which each support a unique and diverse aquatic ecosystem. An initial survey of water chemistries indicates that each sink has a unique chemical identity and neutral to alkaline pH. Sinkholes are filled by one or more artesian springs, groundwater seepage and possible hydrothermal water sources. We present results of water and gas analyses of 10 representative sinkholes, sampled during spring and summer, 2008. Analytical results, including major ions, metals (arsenic, selenium, iron), and gas chemistries are compared with monitoring well data from wells found to the north of the Refuge, along the Pecos River, and to the west, along the Pecos Slope - the regional aquifer recharge area. Well samples representative of regional groundwater provide potential end member perspectives for sources of sinkhole waters. Samples were collected incrementally from the surface to sinkhole floor to profile the limnological structure and to assess chemical variation and mixing through the water column. A sonde was deployed to measure and record physical parameters. Results of the analysis are used to describe the geochemical mixing that is occurring within the sinks. As each sink behaves as an independent unit, those separated by less than 10 meters can have dramatic variability in chemical signature and biological influence. For example, among the 29 sinks sampled during the initital survey, chloride concentrations range from 1.912x10-3 to 1.405 mol/kg; sulfate from 7.204x10-4 to 0.1364 mol/kg; and fluoride from 3.579x10-4 to 3.453x10-3 mol/kg. Along the Pecos Slope, groundwater chloride concentrations increase from less than 1.410x10-3 mol/kg near the major recharge area in the Sacramento Mountains to 0.141 mol

  5. Uranium-thorium isotope geochemistry of saline ground waters from central Missouri

    SciTech Connect

    Banner, J.L.; Chen, J.H.; Wasserburg, G.J.

    1989-03-01

    The isotopic and elemental distributions of uranium and thorium were examined in a suite of saline ground waters from central Missouri using mass spectrometric techniques. The waters were sampled from natural springs and artesian wells in Mississippian and Ordovician aquifers and have a wide range in salinity (5 to 26 /per thousand/), deltaD (/minus/108 to /minus/45 /per thousand/), and delta/sup 18/O (/minus/14.7 to /minus/6.5 /per thousand/) values. The suite of samples has a large range in /sup 238/U (50 to 200 x 10/sup /minus/12/g/g) and /sup 232/Th (0.3 to 9.1 x 10/sup /minus/12/g/g) concentrations and extremely high /sup 234/U//sup 238/U activity ratios ranging from 2.15 to 16.0. These isotopic compositions represent pronounced uranium-series disequilibrium compared with the value of modern seawater (1.15) or the equilibrium value (1.00). For such /sup 234/U-enriched waters, /sup 234/U//sup 238/U isotope ratios can be determined with a precision of /+-/ 10 /per thousand/ (2sigma) on 10 mL of sample and less than /+-/5 /per thousand/ on 100 mL. In contrast to the large /sup 234/U enrichments, /sup 230/Th//sup 238/U activity ratios in the ground waters are significantly lower than the equilibrium value. The more saline samples have markedly higher /sup 234/U//sup 238/U activity ratios and lower deltaD and delta/sup 18/O values. Unfiltered and filtered (< 0.1 ..mu..m) aliquots of a saline sample have the same isotopic composition and concentration of uranium, indicating uranium essentially occurs entirely as a dissolved species. The filtered/unfiltered concentration ratio for thorium in this sample is 0.29, demonstrating the predominant association of thorium with particulates.

  6. The occurrence and geochemistry of salty ground water in the northern Atlantic Coastal Plain

    SciTech Connect

    Meisler, H.

    1989-01-01

    Salty ground water underlies freshwater in the eastern part of the northern Atlantic Coastal Plain. The transition zone between freshwater and saltwater is represented in this report by a series of maps showing the depths to chloride concentrations of 250, 1,000, 5,000, 10,000, and 18,000 milligrams per liter. The maps are based on chloride data obtained from water-quality analyses supplemented by interpretation of borehole spontaneous-potential and resistivity logs. They indicate that the transition zone between 250 and 18,000 milligrams of chloride per liter ranges in thickness from 400 to 2,200 feet. The saltwater-freshwater transition zone is shallowest in North Carolina and deepens northward, attaining its greatest depth in Maryland and New Jersey. It deepens inland from the coast except locally in North Carolina and in New Jersey, where it is deepest along the coast. Depth to the saltwater-freshwater transition zone is partly controlled by the natural flow pattern of fresh ground water; areas where the transition zone is relatively shallow commonly coincide with areas of natural ground-water discharge. The broad saltwater-freshwater transition zone is attributed to the mixing of freshwater and saltwater caused by large-scale sea-level fluctuations, probably during the late Tertiary and Quaternary. Mixing of freshwater with seawater predominates in North Carolina, whereas mixing with brine is more significant from Virginia to New Jersey. The most likely origin of the brine is from the leaching of evaporitic strata beneath the Continental Shelf and the westward movement of the brines, initially during basinal compaction and subsequently during periods of sea-level rise.

  7. Geohydrology and geochemistry near coastal ground-water-discharge areas of the Eastern Shore, Virginia

    USGS Publications Warehouse

    Speiran, Gary K.

    1996-01-01

    Local and regional patterns in the organic content of sediments in the surficial aquifer, as reflected in topography and land use, control dissolved oxygen and nitrate concentrations in ground water that recharged through agricultural fields and flowed beneath riparian woodlands. Dissolved oxygen and nitrate concentrations decreased beneath the woodlands as a result of changes in the organic content of the sediments that resulted from deposition of the sediments, not the current presence of riparian woodlands.

  8. Geochemistry of Lake Van pore water and sediment, or How to distinguish climatic from diagenetic signals?

    NASA Astrophysics Data System (ADS)

    Kwiecien, Ola; Tomonaga, Yama; Brennwald, Matthias S.; Randlett, Marie-Eve; Peterse, Francien; Bechtel, Achim; van der Meer, Marcel; Stockhecke, Mona; Bucher, Stefan; Anselmetti, Flavio; Litt, Thomas; Schubert, Carsten J.; Kipfer, Rolf

    2014-05-01

    Lake Van is a terminal soda lake located in a semiarid region (eastern Anatolia, Turkey). Its geographical setting makes Lake Van a superb archive of paleoenvironmental changes. One of the aims of the ICDP PALEOVAN project is the reconstruction of the hydrological and climatic variability in the eastern Mediterranean region and the Near East on glacial/interglacial and millennial time scales. We applied a multi-proxy approach to distinguish the environmental synsedimentary imprint and the postsedimentary diagenetic changes. Microfaunal evidence, carbonate isotopic composition (d18O, d13C), molecular proxies (BIT, ACE) and isotopic composition of lipid biomarkers (dD) are matched with isotopic and elemental composition (d18O, dD, Mg, Ca, Sr, Cl, salinity) of sediment pore-water. An excellent correspondence between these proxies indicates that the elemental composition of pore water in Lake Van does not result from diagenetic changes, but, unlike in many cases known from marine environment, represents to some extent relicts of 'paleolake-water'. On the contrary, the stable isotopic composition of the pore water (d18O, dD) seems to reflect more recent hydrological regime dominated by precipitation/evaporation changes. As salinity and chlorine concentration changes mimic the isotopic composition of biomarkers for the last 140 ka, we use pore-water data to quantify changes in the lake level. Our reconstruction (Tomonaga et al., in review) is in line with previous studies on lake terraces (Kuzucuoglu et al., 2010) and seismic surveys (Cukur et al., 2012) showing a major transgression of up to 105 m with respect to the current lake level during the last interglacial (MIS5e), and a major regression of ~145 m at ~30 ka BP during the last glacial. Kuzucuoglu et al. (2010) Formation of the Upper Pleistocene terraces of Lake Van (Turkey). Journal of Quaternary Science 25, 1124-1137. Cukur et al. (2012) Sedimentary evolution of Lake Van (Eastern Turkey) reconstructed from high

  9. Fluoride geochemistry of thermal waters in Yellowstone National Park: I. Aqueous fluoride speciation

    USGS Publications Warehouse

    Deng, Y.; Nordstrom, D.K.; Blaine, McCleskey R.

    2011-01-01

    Thermal water samples from Yellowstone National Park (YNP) have a wide range of pH (1-10), temperature, and high concentrations of fluoride (up to 50mg/l). High fluoride concentrations are found in waters with field pH higher than 6 (except those in Crater Hills) and temperatures higher than 50??C based on data from more than 750 water samples covering most thermal areas in YNP from 1975 to 2008. In this study, more than 140 water samples from YNP collected in 2006-2009 were analyzed for free-fluoride activity by ion-selective electrode (ISE) method as an independent check on the reliability of fluoride speciation calculations. The free to total fluoride concentration ratio ranged from <1% at low pH values to >99% at high pH. The wide range in fluoride activity can be explained by strong complexing with H+ and Al3+ under acidic conditions and lack of complexing under basic conditions. Differences between the free-fluoride activities calculated with the WATEQ4F code and those measured by ISE were within 0.3-30% for more than 90% of samples at or above 10-6 molar, providing corroboration for chemical speciation models for a wide range of pH and chemistry of YNP thermal waters. Calculated speciation results show that free fluoride, F-, and major complexes (HF(aq)0, AlF2+, AlF2+ and AlF30) account for more than 95% of total fluoride. Occasionally, some complex species like AlF4-, FeF2+, FeF2+, MgF+ and BF2(OH)2- may comprise 1-10% when the concentrations of the appropriate components are high. According to the simulation results by PHREEQC and calculated results, the ratio of main fluoride species to total fluoride varies as a function of pH and the concentrations and ratios of F and Al. ?? 2011.

  10. Fluoride geochemistry of thermal waters in Yellowstone National Park: I. Aqueous fluoride speciation

    NASA Astrophysics Data System (ADS)

    Deng, Yamin; Nordstrom, D. Kirk; Blaine McCleskey, R.

    2011-08-01

    Thermal water samples from Yellowstone National Park (YNP) have a wide range of pH (1-10), temperature, and high concentrations of fluoride (up to 50 mg/l). High fluoride concentrations are found in waters with field pH higher than 6 (except those in Crater Hills) and temperatures higher than 50 °C based on data from more than 750 water samples covering most thermal areas in YNP from 1975 to 2008. In this study, more than 140 water samples from YNP collected in 2006-2009 were analyzed for free-fluoride activity by ion-selective electrode (ISE) method as an independent check on the reliability of fluoride speciation calculations. The free to total fluoride concentration ratio ranged from <1% at low pH values to >99% at high pH. The wide range in fluoride activity can be explained by strong complexing with H + and Al 3+ under acidic conditions and lack of complexing under basic conditions. Differences between the free-fluoride activities calculated with the WATEQ4F code and those measured by ISE were within 0.3-30% for more than 90% of samples at or above 10 -6 molar, providing corroboration for chemical speciation models for a wide range of pH and chemistry of YNP thermal waters. Calculated speciation results show that free fluoride, F -, and major complexes ( HF(aq)0, AlF 2+, AlF2+ and AlF30) account for more than 95% of total fluoride. Occasionally, some complex species like AlF4-, FeF 2+, FeF2+, MgF + and BF(OH)2- may comprise 1-10% when the concentrations of the appropriate components are high. According to the simulation results by PHREEQC and calculated results, the ratio of main fluoride species to total fluoride varies as a function of pH and the concentrations and ratios of F and Al.

  11. Cr(VI) Occurrence and Geochemistry in Water From Public-Supply Wells in California

    SciTech Connect

    Izbicki, John A.; Wright, Michael T.; Seymour, Whitney A.; McCleskey, R. Blaine; Fram, Miranda S.; Belitz, Kenneth; Esser, Bradley K.

    2015-08-18

    Hexavalent chromium, Cr(VI), in 918 wells sampled throughout California between 2004 and 2012 by the Groundwater Ambient Monitoring and Assessment Program—Priority Basin Project (GAMA—PBP) ranged from less than the study reporting limit (SRL) of 1 microgram per liter (μg/L) to 32 μg/L. Statewide, Cr(VI) was reported in 31 percent of sampled wells and equaled or exceeded the recently established (2014) California Maximum Contaminant Level (MCL) for Cr(VI) of 10 μg/L in 4 percent of sampled wells. Cr(VI) data collected for regulatory purposes overestimate Cr(VI) occurrence. Ninety percent of chromium was present as Cr(VI), which was detected more frequently and at higher concentrations in alkaline (pH > 8), oxic water, and more frequently in agricultural and urban land uses compared to native land uses. Chemical, isotopic (tritium and carbon-14), and noble-gas data show high Cr(VI) in water from wells in alluvial aquifers in the southern California deserts result from long groundwater-residence times and geochemical reactions such as silicate weathering that increase pH, while oxic conditions persist. High Cr(VI) in water from wells in alluvial aquifers along the west-side of the Central Valley results from high-chromium abundance in source rock eroded to form those aquifers, and areal recharge processes (including irrigation return) that mobilize chromium from the unsaturated zone. Cr(VI) co-occurred with oxyanions having similar chemistry, including vanadium, selenium, and uranium. Cr(VI) was positively correlated with nitrate, consistent with increased concentrations in areas of agricultural land use and mobilization of chromium from the unsaturated zone by irrigation return.

  12. Cr(VI) Occurrence and Geochemistry in Water From Public-Supply Wells in California

    DOE PAGESBeta

    Izbicki, John A.; Wright, Michael T.; Seymour, Whitney A.; McCleskey, R. Blaine; Fram, Miranda S.; Belitz, Kenneth; Esser, Bradley K.

    2015-08-18

    Hexavalent chromium, Cr(VI), in 918 wells sampled throughout California between 2004 and 2012 by the Groundwater Ambient Monitoring and Assessment Program—Priority Basin Project (GAMA—PBP) ranged from less than the study reporting limit (SRL) of 1 microgram per liter (μg/L) to 32 μg/L. Statewide, Cr(VI) was reported in 31 percent of sampled wells and equaled or exceeded the recently established (2014) California Maximum Contaminant Level (MCL) for Cr(VI) of 10 μg/L in 4 percent of sampled wells. Cr(VI) data collected for regulatory purposes overestimate Cr(VI) occurrence. Ninety percent of chromium was present as Cr(VI), which was detected more frequently and atmore » higher concentrations in alkaline (pH > 8), oxic water, and more frequently in agricultural and urban land uses compared to native land uses. Chemical, isotopic (tritium and carbon-14), and noble-gas data show high Cr(VI) in water from wells in alluvial aquifers in the southern California deserts result from long groundwater-residence times and geochemical reactions such as silicate weathering that increase pH, while oxic conditions persist. High Cr(VI) in water from wells in alluvial aquifers along the west-side of the Central Valley results from high-chromium abundance in source rock eroded to form those aquifers, and areal recharge processes (including irrigation return) that mobilize chromium from the unsaturated zone. Cr(VI) co-occurred with oxyanions having similar chemistry, including vanadium, selenium, and uranium. Cr(VI) was positively correlated with nitrate, consistent with increased concentrations in areas of agricultural land use and mobilization of chromium from the unsaturated zone by irrigation return.« less

  13. Geochemistry of summit fumarole vapors and flanking thermal/mineral waters at Popocatepetl Volcano, Mexico

    SciTech Connect

    Werner, C.; Goff, F.; Janik, C.J.

    1997-06-01

    Popocatepetl Volcano is potentially devastating to populations living in the greater Mexico City area. Systematic monitoring of fumarole gases and flanking thermal/mineral springs began in early 1994 after increased fumarolic and seismic activity were noticed in 1991. These investigations had two major objectives: (1) to determine if changes in magmatic conditions beneath Popocatepetl might be reflected by chemical changes in fumarolic discharges and (2) to determine if thermal/mineral spring waters in the vicinity of Popocatepetl are geochemically related to or influences by the magmatic system. This report summarizes results from these two discrete studies.

  14. Mineralogy and geochemistry of efflorescent minerals on mine tailings and their potential impact on water chemistry.

    PubMed

    Grover, B P C; Johnson, R H; Billing, D G; Weiersbye, I M G; Tutu, H

    2016-04-01

    In the gold mining Witwatersrand Basin of South Africa, efflorescent mineral crusts are a common occurrence on and nearby tailings dumps during the dry season. The crusts are readily soluble and generate acidic, metal- and sulphate-rich solutions on dissolution. In this study, the metal content of efflorescent crusts at an abandoned gold mine tailings dump was used to characterise surface and groundwater discharges from the site. Geochemical modelling of the pH of the solution resulting from the dissolution of the crusts was used to better understand the crusts' potential impact on water chemistry. The study involved two approaches: (i) conducting leaching experiments on oxidised and unoxidised tailings using artificial rainwater and dilute sulphuric acid and correlating the composition of crusts to these leachates and (ii) modelling the dissolution of the crusts in order to gain insight into their mineralogy and their potential impact on receiving waters. The findings suggested that there were two chemically distinct discharges from the site, namely an aluminium- and magnesium-rich surface water plume and an iron-rich groundwater plume. The first plume was observed to originate from the oxidised tailings following leaching with rainwater while the second plume originated from the underlying unoxidised tailings with leaching by sulphuric acid. Both groups of minerals forming from the respective plumes were found to significantly lower the pH of the receiving water with simulations of their dissolution found to be within 0.2 pH units of experimental values. It was observed that metals in a low abundance within the crust (for example, iron) had a stronger influence on the pH of the resulting solutions than metals in a greater abundance (aluminium or magnesium). Techniques such as powder X-ray diffraction (PXRD) and in situ mineral determination techniques such as remote sensing can effectively determine the dominant mineralogy. However, the minerals or metals

  15. Water and gas geochemistry of the Calatrava Volcanic Province (CVP) hydrothermal system (Ciudad Real, central Spain)

    NASA Astrophysics Data System (ADS)

    Vaselli, Orlando; Nisi, Barbara; Tassi, Franco; Giannini, Luciano; Grandia, Fidel; Darrah, Tom; Capecchiacci, Francesco; del Villar, Pèrez

    2013-04-01

    An extensive geochemical and isotopic investigation was carried out in the water and gas discharges of the Late Miocene-Quaternary Calatrava Volcanic Province (CVP) (Ciudad Real, Spain) with the aim reconstruct the fluid circulation in the area. CVP consists of a series of scattered (monogenetic) vents from where alkaline lava flows and pyroclastic deposits formed in two different periods. The first stage (8.7-6.4 Ma) mainly included ultra-potassic mafic extrusives, whilst the second stage (4.7-1.75 Ma) prevalently originated alkaline and ultra-alkaline volcanics. Both stages were followed by a volcanic activity that extended up to 1.3 and 0.7 Ma, respectively. This area can likely be regarded as one of the most important emitting zones of CO2 in the whole Peninsular Spain along with that of Selva-Emporda in northeastern Spain (Cataluña) and it can be assumed as one of the best examples of natural analogues of CO2 leakages in Spain. This latter aspect is further evidenced by the relatively common water-gas blast events that characterize the CCVF. In the last few years the presence of a CO2-pressurized reservoir at a relatively shallow level as indeed caused several small-sized explosion particularly during the drilling of domestic wells. The fluid discharging sites are apparently aligned along well-defined directions: NW-SE and NNW-SSE and subordinately, ENE-WSW, indicating a clear relationship between the thermal discharges and the volcanic centers that also distribute along these lineaments. The CVP waters are mostly hypothermal (up to 33 °C) and are generally Mg(Ca)-HCO3 in composition and occasionally show relatively high concentrations of Fe and Mn, with pH and electrical conductivity down to 5.5 and up to 6.5 mS/cm, respectively. The oxygen and hydrogen isotopes suggest a meteoric origin for these waters. The mantle source of these volcanic products is apparently preserved in the many CO2-rich (up to 990,000 mmol/mol) gas discharges that characterize CVP

  16. Ultrafast dynamics of water in cationic micelles

    NASA Astrophysics Data System (ADS)

    Dokter, Adriaan M.; Woutersen, Sander; Bakker, Huib J.

    2007-03-01

    The effect of confinement on the dynamical properties of liquid water is investigated for water enclosed in cationic reverse micelles. The authors performed mid-infrared ultrafast pump-probe spectroscopy on the OH-stretch vibration of isotopically diluted HDO in D2O in cetyltrimethylammonium bromide (CTAB) reverse micelles of various sizes. The authors observe that the surfactant counterions are inhomogeneously distributed throughout the reverse micelle, and that regions of extreme salinity occur near the interfacial Stern layer. The authors find that the water molecules in the core of the micelles show similar orientational dynamics as bulk water, and that water molecules in the counterion-rich interfacial region are much less mobile. An explicit comparison is made with the dynamics of water confined in anionic sodium bis(2-ethythexyl) sulfosuccinate (AOT) reverse micelles. The authors find that interfacial water in cationic CTAB reverse micelles has a higher orientational mobility than water in anionic AOT reverse micelles.

  17. Spatial and temporal dynamics of sediment in contrasted mountainous watersheds (Mexican transvolcanic belt and French Southern Alps) combining river gauging, elemental geochemistry and fallout radionuclides

    NASA Astrophysics Data System (ADS)

    Evrard, O.; Navratil, O.; Gratiot, N.; Némery, J.; Duvert, C.; Ayrault, S.; Lefèvre, I.; Legout, C.; Bonté, P.; Esteves, M.

    2009-12-01

    In mountainous environments, an excessive fine sediment supply to the rivers typically leads to an increase in water turbidity, contaminant transport and a rapid filling of reservoirs. This situation is particularly problematic in regions where water reservoirs are used to provide drinking water to large cities (e.g. in central Mexico) or where stream water is used to run hydroelectric power plants (e.g. in the French Southern Alps). In such areas, sediment source areas first need to be delineated and sediment fluxes between hillslopes and the river system must be better understood before implementing efficient erosion control measures. In this context, the STREAMS (« Sediment Transport and Erosion Across MountainS ») project funded by the French National Research Agency (ANR) aims at understanding the spatial and temporal dynamics of sediment at the scale of mountainous watersheds (between 500 - 1000 km2) located in contrasted environments. This 3-years study is carried out simultaneously in a volcanic watershed located in the Mexican transvolcanic belt undergoing a subhumid tropical climate, as well as in a sedimentary watershed of the French Southern Alps undergoing a transitional climate with Mediterranean and continental influences. One of the main specificities of this project consists in combining traditional monitoring techniques (i.e. installation of river gauges, turbidimeters and sediment samplers in several sub-catchments) and sediment fingerprinting using elemental geochemistry (measured by Instrumental Neutron Activation Analysis - INAA - and Inductively Coupled Plasma - Mass Spectrometry - ICP-MS) and fallout radionuclides (measured by gamma spectrometry). In the French watershed, geochemical analysis allows outlining different sediment sources (e.g. the contribution of calcareous vs. marl-covered sub-watersheds). Radionuclide ratios (e.g.Be-7/Cs-137) allow identifying the dominant erosion processes occurring within the watershed. Areas mostly

  18. Sulfur geochemistry of hydrothermal waters in Yellowstone National Park, Wyoming, USA. III. An anion-exchange resin technique for sampling and preservation of sulfoxyanions in natural waters

    USGS Publications Warehouse

    Druschel, G.K.; Schoonen, M.A.A.; Nordstorm, D.K.; Ball, J.W.; Xu, Y.; Cohn, C.A.

    2003-01-01

    A sampling protocol for the retention, extraction, and analysis of sulfoxyanions in hydrothermal waters has been developed in the laboratory and tested at Yellowstone National Park and Green Lake, NY. Initial laboratory testing of the anion-exchange resin Bio-Rad??? AG1-X8 indicated that the resin was well suited for the sampling, preservation, and extraction of sulfate and thiosulfate. Synthetic solutions containing sulfate and thiosulfate were passed through AG1-X8 resin columns and eluted with 1 and 3 M KCl, respectively. Recovery ranged from 89 to 100%. Comparison of results for water samples collected from five pools in Yellowstone National Park between on-site IC analysis (U.S. Geological Survey mobile lab) and IC analysis of resin-stored sample at SUNY-Stony Brook indicates 96 to 100% agreement for three pools (Cinder, Cistern, and an unnamed pool near Cistern) and 76 and 63% agreement for two pools (Sulfur Dust and Frying Pan). Attempts to extract polythionates from the AG1-X8 resin were made using HCl solutions, but were unsuccessful. Bio-Rad??? AG2-X8, an anion-exchange resin with weaker binding sites than the AG1-X8 resin, is better suited for polythionate extraction. Sulfate and thiosulfate extraction with this resin has been accomplished with KCl solutions of 0.1 and 0.5 M, respectively. Trithionate and tetrathionate can be extracted with 4 M KCl. Higher polythionates can be extracted with 9 M hydrochloric acid. Polythionate concentrations can then be determined directly using ion chromatographic methods, and laboratory results indicate recovery of up to 90% for synthetic polythionate solutions using AG2-X8 resin columns. ?? The Royal Society of Chemistry and the Division of Geochemistry of the American Chemical Society 2003.

  19. Dynamic Programming Applications in Water Resources

    NASA Astrophysics Data System (ADS)

    Yakowitz, Sidney

    1982-08-01

    The central intention of this survey is to review dynamic programming models for water resource problems and to examine computational techniques which have been used to obtain solutions to these problems. Problem areas surveyed here include aqueduct design, irrigation system control, project development, water quality maintenance, and reservoir operations analysis. Computational considerations impose severe limitation on the scale of dynamic programming problems which can be solved. Inventive numerical techniques for implementing dynamic programming have been applied to water resource problems. Discrete dynamic programming, differential dynamic programming, state incremental dynamic programming, and Howard's policy iteration method are among the techniques reviewed. Attempts have been made to delineate the successful applications, and speculative ideas are offered toward attacking problems which have not been solved satisfactorily.

  20. Sulfur geochemistry of hydrothermal waters in Yellowstone National Park: I. The origin of thiosulfate in hot spring waters

    USGS Publications Warehouse

    Xu, Y.; Schoonen, M.A.A.; Nordstrom, D.K.; Cunningham, K.M.; Ball, J.W.

    1998-01-01

    Thiosulfate (S2O2-3), polythionate (SxO2-6), dissolved sulfide (H2S), and sulfate (SO2-4) concentrations in thirty-nine alkaline and acidic springs in Yellowstone National Park (YNP) were determined. The analyses were conducted on site, using ion chromatography for thiosulfate, polythionate, and sulfate, and using colorimetry for dissolved sulfide. Thiosulfate was detected at concentrations typically less than 2 ??mol/L in neutral and alkaline chloride springs with low sulfate concentrations (C1-/SO2-4 > 25). The thiosulfate concentration levels are about one to two orders of magnitude lower than the concentration of dissolved sulfide in these springs. In most acid sulfate and acid sulfate-chloride springs (Cl-/SO2-4 < 10), thiosulfate concentrations were also typically lower than 2 ??mol/L. However, in some chloride springs enriched with sulfate (Cl-/SO2-4 between 10 to 25), thiosulfate was found at concentrations ranging from 9 to 95 ??mol/L, higher than the concentrations of dissolved sulfide in these waters. Polythionate was detected only in Cinder Pool, Norris Geyser basin, at concentrations up to 8 ??mol/L, with an average S-chain-length from 4.1 to 4.9 sulfur atoms. The results indicate that no thiosulfate occurs in the deeper parts of the hydrothermal system. Thiosulfate may form, however, from (1) hydrolysis of native sulfur by hydrothermal solutions in the shallower parts (<50 m) of the system, (2) oxidation of dissolved sulfide upon mixing of a deep hydrothermal water with aerated shallow groundwater, and (3) the oxidation of dissolved sulfide by dissolved oxygen upon discharge of the hot spring. Upon discharge of a sulfide-containing hydrothermal water, oxidation proceeds rapidly as atmospheric oxygen enters the water. The transfer of oxygen is particularly effective if the hydrothermal discharge is turbulent and has a large surface area.

  1. Capillary filling dynamics of water in nanopores

    NASA Astrophysics Data System (ADS)

    Bakli, Chirodeep; Chakraborty, Suman

    2012-10-01

    We portray a universal description of dynamic slip-stick behavior of water flowing through nanoscale pores. Based on fundamental molecular transport considerations, we derive a generalized constitutive model for describing resistive forces acting on the water column in a capillary that is being dynamically filled, as a combined function of the meniscus height, surface wettability, and roughness. This effectively acts like a unique signature of nanopore imbibition characteristics of water, which, when substituted in a simple one-dimensional force balance model agrees quantitatively with results from molecular dynamics simulations for a general class of problems, without necessitating the employment of any artificially tunable fitting parameters.

  2. Water losses dynamic modelling in water distribution networks

    NASA Astrophysics Data System (ADS)

    Puleo, Valeria; Milici, Barbara

    2015-12-01

    In the last decades, one of the main concerns of the water system managers have been the minimisation of water losses, that frequently reach values of 30% or even 70% of the volume supplying the water distribution network. The economic and social costs associated with water losses in modern water supply systems are rapidly rising to unacceptably high levels. Furthermore, the problem of the water losses assumes more and more importance mainly when periods of water scarcity occur or when not sufficient water supply takes part in areas with fast growth. In the present analysis, a dynamic model was used for estimating real and apparent losses of a real case study. A specific nodal demand model reflecting the user's tank installation and a specific apparent losses module were implemented. The results from the dynamic model were compared with the modelling estimation based on a steady-state approach.

  3. Sulfur geochemistry of hydrothermal waters in Yellowstone National Park. 1: The origin of thiosulfate in hot spring waters

    SciTech Connect

    Xu, Y.; Schoonen, M.A.A.; Nordstrom, D.K.; Cunningham, K.M.; Ball, J.W.

    1998-12-01

    Thiosulfate (S{sub 2}O{sub 3}{sup 2{minus}}), polythionate (S{sub x}O{sub 6}{sup 2{minus}}), dissolved sulfide (H{sub 2}S), and sulfate (SO{sub 4}{sup 2{minus}}) concentrations in thirty-nine alkaline and acidic springs in Yellowstone National Park (YNP) were determined. The analyses were conducted on site, using ion chromatography for thiosulfate, polythionate, and sulfate, and using colorimetry for dissolved sulfide. Thiosulfate was detected at concentrations typically less than 2 {micro}mol/L in neutral and alkaline chloride springs with low sulfate concentrations (Cl{sup {minus}}/SO{sub 4}{sup 2{minus}} > 25). The thiosulfate concentration levels are about one to two orders of magnitude lower than the concentration of dissolved sulfide in these springs. In most acid sulfate and acid sulfate-chloride springs (Cl{sup {minus}}/SO{sub 4}{sup 2{minus}} < 10), thiosulfate concentrations were also typically lower than 2 {micro}mol/L. However, in some chloride springs enriched with sulfate (Cl{sup {minus}}/SO{sub 4}{sup 2{minus}} between 10 and 25), thiosulfate was found at concentrations ranging from 9 to 95 {micro}mol/L, higher than the concentrations of dissolved sulfide in these waters. Polythionate was detected only in Cinder Pool, Norris Geyser basin, at concentrations up to 8 {micro}mol/L, with an average S-chain-length from 4.1 to 4.9 sulfur atoms. The results indicate that no thiosulfate occurs in the deeper parts of the hydrothermal system. Thiosulfate may form, however, from (1) hydrolysis of native sulfur by hydrothermal solutions in the shallower parts (<50 m) of the system, (2) oxidation of dissolved sulfide upon mixing of a deep hydrothermal water with aerated shallow groundwater, and (3) the oxidation of dissolved sulfide by dissolved oxygen upon discharge of the hot spring. Upon discharge of a sulfide-containing hydrothermal water, oxidation proceeds rapidly as atmospheric oxygen enters the water. The transfer of oxygen is particularly effective if the

  4. Structure and dynamics of complex liquid water: Molecular dynamics simulation

    NASA Astrophysics Data System (ADS)

    S, Indrajith V.; Natesan, Baskaran

    2015-06-01

    We have carried out detailed structure and dynamical studies of complex liquid water using molecular dynamics simulations. Three different model potentials, namely, TIP3P, TIP4P and SPC-E have been used in the simulations, in order to arrive at the best possible potential function that could reproduce the structure of experimental bulk water. All the simulations were performed in the NVE micro canonical ensemble using LAMMPS. The radial distribution functions, gOO, gOH and gHH and the self diffusion coefficient, Ds, were calculated for all three models. We conclude from our results that the structure and dynamical parameters obtained for SPC-E model matched well with the experimental values, suggesting that among the models studied here, the SPC-E model gives the best structure and dynamics of bulk water.

  5. Medical geochemistry of tropical environments

    NASA Astrophysics Data System (ADS)

    Dissanayake, C. B.; Chandrajith, Rohana

    1999-10-01

    Geochemically, tropical environments are unique. This uniqueness stems from the fact that these terrains are continuously subjected to extreme rainfall and drought with resulting strong geochemical fractionation of elements. This characteristic geochemical partitioning results in either severe depletion of elements or accumulation to toxic levels. In both these situations, the effect on plant, animal and human health is marked. Medical geochemistry involves the study of the relationships between the geochemistry of the environment in which we live and the health of the population living in this particular domain. Interestingly, the relationships between geochemistry and health are most marked in the tropical countries, which coincidentally are among the poorest in the world. The very heavy dependence on the immediate environment for sustainable living in these lands enables the medical geochemist to observe correlations between particular geochemical provinces and the incidence of certain diseases unique to these terrains. The aetiology of diseases such as dental and skeletal fluorosis, iodine deficiency disorders, diseases of humans and animals caused by mineral imbalances among others, lie clearly in the geochemical environment. The study of the chemistry of the soils, water and stream sediments in relation to the incidence of geographically distributed diseases in the tropics has not only opened up new frontiers in multidisciplinary research, but has offered new challenges to the medical profession to seriously focus attention on the emerging field of medical geochemistry with the collaboration of geochemists and epidemiologists.

  6. Estancia Basin dynamic water budget.

    SciTech Connect

    Thomas, Richard P.

    2004-09-01

    The Estancia Basin lies about 30 miles to the east of Albuquerque, NM. It is a closed basin in terms of surface water and is somewhat isolated in terms of groundwater. Historically, the primary natural outlet for both surface water and groundwater has been evaporation from the salt lakes in the southeastern portion of the basin. There are no significant watercourses that flow into this basin and groundwater recharge is minimal. During the 20th Century, agriculture grew to become the major user of groundwater in the basin. Significant declines in groundwater levels have accompanied this agricultural use. Domestic and municipal use of the basin groundwater is increasing as Albuquerque population continues to spill eastward into the basin, but this use is projected to be less than 1% of agricultural use well into the 21st Century. This Water Budget model keeps track of the water balance within the basin. The model considers the amount of water entering the basin and leaving the basin. Since there is no significant surface water component within this basin, the balance of water in the groundwater aquifer constitutes the primary component of this balance. Inflow is based on assumptions for recharge made by earlier researchers. Outflow from the basin is the summation of the depletion from all basin water uses. The model user can control future water use within the basin via slider bars that set values for population growth, water system per-capita use, agricultural acreage, and the types of agricultural diversion. The user can also adjust recharge and natural discharge within the limits of uncertainty for those parameters. The model runs for 100 years beginning in 1940 and ending in 2040. During the first 55 years model results can be compared to historical data and estimates of groundwater use. The last 45 years are predictive. The model was calibrated to match to New Mexico Office of State Engineer (NMOSE) estimates of aquifer storage during the historical period by

  7. Nucleation dynamics of water nanodroplets.

    PubMed

    Bhattacharya, Dipanjan; Bosman, Michel; Mokkapati, Venkata R S S; Leong, Fong Yew; Mirsaidov, Utkur

    2014-04-01

    The origin of the condensation of water begins at the nanoscale, a length-scale that is challenging to probe for liquids. In this work we directly image heterogeneous nucleation of water nanodroplets by in situ transmission electron microscopy. Using gold nanoparticles bound to a flat surface as heterogeneous nucleation sites, we observe nucleation and growth of water nanodroplets. The growth of nanodroplet radii follows the power law: R(t)~(t-t 0) β , where β~0.2-0.3. PMID:24667092

  8. Geochemistry driven trends in microbial diversity and function across a temperature transect of a shallow water hydrothermal system off Milos (Greece)

    NASA Astrophysics Data System (ADS)

    Bühring, Solveig I.; Amend, Jan P.; Gómez Sáez, Gonzalo V.; Häusler, Stefan; Hinrichs, Kai-Uwe; Pichler, Thomas; Pop Ristova, Petra; Price, Roy E.; Santi, Ioulia; Sollich, Miriam

    2014-05-01

    The shallow water hydrothermal vents off Milos Island, Greece, discharge hot, slightly acidic, reduced fluids into colder, slightly alkaline, oxygenated seawater. Gradients in temperature, pH, and geochemistry are established as the two fluids mix, leading to the formation of various microbial microniches. In contrast to deep-sea hydrothermal systems, the availability of sun light allows for a combination of photo- and chemotrophic carbon fixation. Despite the comparably easy accessibility of shallow water hydrothermal systems, little is known about their microbial diversity and functioning. We present data from a shallow hydrothermal system off Milos Island, one of the most hydrothermally active regions in the Mediterranean Sea. The physico-chemical changes from ambient seafloor to hydrothermal area were investigated and documented by in situ microsensor profiling of temperature, pH, total reduced sulfur and dissolved oxygen alongside porewater geochemistry. The spatial microbial diversity was determined using a combination of gene- and lipid-based approaches, whereas microbial functioning was assessed by stable isotope probing experiments targeting lipid biomarkers. In situ microprofiles indicated an extreme environment with steep gradients, offering a variety of microniches for metabolically diverse microbial communities. We sampled a transect along a hydrothermal patch, following an increase in sediment surface temperature from background to 90°C, including five sampling points up to 20 cm sediment depth. Investigation of the bacterial diversity using ARISA revealed differences in the community structure along the geochemical gradients, with the least similarity between the ambient and highly hydrothermally impacted sites. Furthermore, using multivariate statistical analyses it was shown that variations in the community structure could be attributed to differences in the sediment geochemistry and especially the sulfide content, and only indirectly to shifts in

  9. Subseabed Disposal Project annual report, FY85 to termination of project: Physical Oceanography and Water Column Geochemistry Studies, October 1984 through May 1986

    SciTech Connect

    Kupferman, S.L.

    1987-05-01

    This report covers the work of the Physical Oceanography and Water Column Geochemistry (POWCG) Studies Group of the Subseabed Disposal Project (SDP) from October 1984 to termination of the project in May 1986. The overview of the work includes an introduction, general descriptions of the activities, and a summary. Detailed discussions are included as appendices. During the period of this report the POWCG Studies Group held a meeting to develop a long-term research plan for the Nares Abyssal Plain, which was recently designated as a study area for the Environmental Study Group of the SDP. The POWCG Studies Group has also planned and participated in two interdisciplinary oceanographic missions to the Nares which have resulted in the acquisition of data and samples which can be used to begin to understand the workings of the ecosystem at the site, and for developing a preliminary site assessment. The papers in the appendices have been processed for inclusion in the Energy Data Base.

  10. Cell water dynamics on multiple time scales

    PubMed Central

    Persson, Erik; Halle, Bertil

    2008-01-01

    Water–biomolecule interactions have been extensively studied in dilute solutions, crystals, and rehydrated powders, but none of these model systems may capture the behavior of water in the highly organized intracellular milieu. Because of the experimental difficulty of selectively probing the structure and dynamics of water in intact cells, radically different views about the properties of cell water have proliferated. To resolve this long-standing controversy, we have measured the 2H spin relaxation rate in living bacteria cultured in D2O. The relaxation data, acquired in a wide magnetic field range (0.2 mT–12 T) and analyzed in a model-independent way, reveal water dynamics on a wide range of time scales. Contradicting the view that a substantial fraction of cell water is strongly perturbed, we find that ≈85% of cell water in Escherichia coli and in the extreme halophile Haloarcula marismortui has bulk-like dynamics. The remaining ≈15% of cell water interacts directly with biomolecular surfaces and is motionally retarded by a factor 15 ± 3 on average, corresponding to a rotational correlation time of 27 ps. This dynamic perturbation is three times larger than for small monomeric proteins in solution, a difference we attribute to secluded surface hydration sites in supramolecular assemblies. The relaxation data also show that a small fraction (≈0.1%) of cell water exchanges from buried hydration sites on the microsecond time scale, consistent with the current understanding of protein hydration in solutions and crystals. PMID:18436650

  11. Water dynamics and interactions in water-polyether binary mixtures.

    PubMed

    Fenn, Emily E; Moilanen, David E; Levinger, Nancy E; Fayer, Michael D

    2009-04-22

    Poly(ethylene) oxide (PEO) is a technologically important polymer with a wide range of applications including ion-exchange membranes, protein crystallization, and medical devices. PEO's versatility arises from its special interactions with water. Water molecules may form hydrogen-bond bridges between the ether oxygens of the backbone. While steady-state measurements and theoretical studies of PEO's interactions with water abound, experiments measuring dynamic observables are quite sparse. A major question is the nature of the interactions of water with the ether oxygens as opposed to the highly hydrophilic PEO terminal hydroxyls. Here, we examine a wide range of mixtures of water and tetraethylene glycol dimethyl ether (TEGDE), a methyl-terminated derivative of PEO with 4 repeat units (5 ether oxygens), using ultrafast infrared polarization selective pump-probe measurements on water's hydroxyl stretching mode to determine vibrational relaxation and orientational relaxation dynamics. The experiments focus on the dynamical interactions of water with the ether backbone because TEGDE does not have the PEO terminal hydroxyls. The experiments observe two distinct subensembles of water molecules: those that are hydrogen bonded to other waters and those that are associated with TEGDE molecules. The water orientational relaxation has a fast component of a few picoseconds (water-like) followed by much slower decay of approximately 20 ps (TEGDE associated). The two decay times vary only mildly with the water concentration. The two subensembles are evident even in very low water content samples, indicating pooling of water molecules. Structural change as water content is lowered through either conformational changes in the backbone or increasing hydrophobic interactions is discussed. PMID:19323522

  12. Dynamics of Water Trapped between Hydrophobic Solutes.

    SciTech Connect

    Choudhury, Niharendu; Pettitt, Bernard M.

    2005-03-15

    We describe the model dynamical behavior of the solvent between two nanoscopic hydrophobic solutes. The dynamics of the vicinal water in various sized traps is found to be significantly different from bulk behavior. We consider the dynamics at normal temperature and pressure at three intersolute distances corresponding to the three solvent separated minima in the free energy profile between the solutes with attractions. These three states correspond to one, two, and three intervening layers of water molecules. Results are obtained from a molecular dynamics simulation at constant temperature and pressure (NPT) ensemble. Translational diffusion of water molecules trapped between the two solutes has been analyzed from the velocity correlation function as well as from the mean square displacement of the water molecules. The rotational behavior has been analyzed through the reorientational dynamics of the dipole moment vector of the water molecule by calculating both first and second rank dipole-dipole correlation functions. Both the translational and reorientational mobilities of water are found to be much slower at the smaller separation and increases as the separation between solutes becomes larger. The occupation time distribution functions calculated from the trajectories also show that the relaxation is much slower for the smallest intersolute separation as compared to other wider separations. The sublinear trend in mean square displacement and the stretched exponential decay of the relaxation of dipolar correlation and occupation distribution function indicate that the dynamical behavior of water in the confined region between two large hydrophobic solutes departs from usual Brownian behavior. This behavior is reminiscent of the behavior of water in the vicinity of protein surface clefts or trapped between two domains of a protein.

  13. The dynamics of water striders

    NASA Astrophysics Data System (ADS)

    Hu, David; Chan, Brian; Bush, John W. M.

    2002-11-01

    Water striders Gerridae, or pond skaters, are insects of characteristic length 1cm and weight 10dynes that reside on the surface of water. Their weight is supported by the surface tension force generated by curvature of the free surface, and they propel themselves by driving their central pair of hydrophobic legs in a rowing motion. The previous physical picture for their propulsion relied exclusively on the generation of capillary waves in their wake. This reasoning lead to Denny's Paradox: infant water striders, whose leg speeds are less than the capillary wave speed, are incapable of propeling themselves along the surface. We here resolve this paradox through reporting the results of high-speed photography and particle-tracking studies. Our experiments reveal that the strider transfers momentum to the fluid not only through capillary waves, but through dipolar vortices in the bulk that are shed by its rowing legs. The strider thus generates its thrust by using the meniscii beneath its rowing legs as oars. We have designed and contructed a mechanical water strider, Robostrider II, whose means of propulsion is analogous to, though slightly less elegant than, its natural counterpart.

  14. Low Froude number water entry cavity dynamics

    NASA Astrophysics Data System (ADS)

    Kominiarczuk, Jakub K.

    2005-11-01

    We analyze the dynamics of the projectile and the water entry cavity in low Froude number water impact where both kinetic and gravitational potential energy play a role. An experimental investigation is conducted where the impact and cavity development of billiard balls hitting a calm water surface at Froude number of O(10) are captured using high speed video camera at 1000 to 2000 frames per second. The phenomena associated with water entry at low impact speeds are complex as gravity, cavity pressure, flow separation, and splash generation significantly influence the cavity shape, surface closure and pinch off. For comparison, an existing analytical theory for the dynamics of water entry cavities for very high speeds is generalized and extended to low Froude number regime. In particular, this closed-form solution now accounts for effects of gravity and flow separation around the projectile. The comparison between the analytic solution and experimental results is excellent.

  15. Geochemistry of and radioactivity in ground water of the Highland Rim and Central Basin aquifer systems, Hickman and Maury counties, Tennessee

    USGS Publications Warehouse

    Hileman, G.E.; Lee, R.W.

    1993-01-01

    A reconnaissance of the geochemistry of and radioactivity in ground water from the Highland Rim and Central Basin aquifer systems in Hickman and Maury Counties, Tennessee, was conducted in 1989. Water in both aquifer systems typically is of the calcium or calcium magnesium bicarbonate type, but concentrations of calcium, magnesium, sodium, potassium, chloride, and sulfate are greater in water of the Central Basin system; differences in the concentrations are statistically significant. Dissolution of calcite, magnesium-calcite, dolomite, and gypsum are the primary geochemical processes controlling ground-water chemistry in both aquifer systems. Saturation-state calculations using the computer code WATEQF indicated that ground water from the Central Basin system is more saturated with respect to calcite, dolomite, and gypsum than water from the Highland Rim system. Geochemical environments within each aquifer system are somewhat different with respect to dissolution of magnesium-bearing minerals. Water samples from the Highland Rim system had a fairly constant calcium to magnesium molar ratio, implying congruent dissolution of magnesium-bearing minerals, whereas water samples from the Central Basin system had highly variable ratios, implying either incongruent dissolution or heterogeneity in soluble constituents of the aquifer matrix. Concentrations of radionuclides in water were low and not greatly different between aquifer systems. Median gross alpha activities were 0.54 picocuries per liter in water from each system; median gross beta activities were 1.1 and 2.3 picocuries per liter in water from the Highland Rim and Central Basin systems, respectively. Radon-222 concentrations were 559 and 422 picocuries per liter, respectively. Concentrations of gross alpha and radium in all samples were substantially less than Tennessee?s maximum permissible levels for community water-supply systems. The data indicated no relations between concentrations of dissolved

  16. Temporal changes in microbial ecology and geochemistry in produced water from hydraulically fractured Marcellus shale gas wells.

    PubMed

    Cluff, Maryam A; Hartsock, Angela; MacRae, Jean D; Carter, Kimberly; Mouser, Paula J

    2014-06-01

    Microorganisms play several important roles in unconventional gas recovery, from biodegradation of hydrocarbons to souring of wells and corrosion of equipment. During and after the hydraulic fracturing process, microorganisms are subjected to harsh physicochemical conditions within the kilometer-deep hydrocarbon-bearing shale, including high pressures, elevated temperatures, exposure to chemical additives and biocides, and brine-level salinities. A portion of the injected fluid returns to the surface and may be reused in other fracturing operations, a process that can enrich for certain taxa. This study tracked microbial community dynamics using pyrotag sequencing of 16S rRNA genes in water samples from three hydraulically fractured Marcellus shale wells in Pennsylvania, USA over a 328-day period. There was a reduction in microbial richness and diversity after fracturing, with the lowest diversity at 49 days. Thirty-one taxa dominated injected, flowback, and produced water communities, which took on distinct signatures as injected carbon and electron acceptors were attenuated within the shale. The majority (>90%) of the community in flowback and produced fluids was related to halotolerant bacteria associated with fermentation, hydrocarbon oxidation, and sulfur-cycling metabolisms, including heterotrophic genera Halolactibacillus, Vibrio, Marinobacter, Halanaerobium, and Halomonas, and autotrophs belonging to Arcobacter. Sequences related to halotolerant methanogenic genera Methanohalophilus and Methanolobus were detected at low abundance (<2%) in produced waters several months after hydraulic fracturing. Five taxa were strong indicators of later produced fluids. These results provide insight into the temporal trajectory of subsurface microbial communities after "fracking" and have important implications for the enrichment of microbes potentially detrimental to well infrastructure and natural gas fouling during this process. PMID:24803059

  17. Silicate and carbonate mineral weathering in soil profiles developed on Pleistocene glacial drift (Michigan, USA): Mass balances based on soil water geochemistry

    NASA Astrophysics Data System (ADS)

    Jin, Lixin; Williams, Erika L.; Szramek, Kathryn J.; Walter, Lynn M.; Hamilton, Stephen K.

    2008-02-01

    Geochemistry of soil, soil water, and soil gas was characterized in representative soil profiles of three Michigan watersheds. Because of differences in source regions, parent materials in the Upper Peninsula of Michigan (the Tahquamenon watershed) contain only silicates, while those in the Lower Peninsula (the Cheboygan and the Huron watersheds) have significant mixtures of silicate and carbonate minerals. These differences in soil mineralogy and climate conditions permit us to examine controls on carbonate and silicate mineral weathering rates and to better define the importance of silicate versus carbonate dissolution in the early stage of soil-water cation acquisition. Soil waters of the Tahquamenon watershed are the most dilute; solutes reflect amphibole and plagioclase dissolution along with significant contributions from atmospheric precipitation sources. Soil waters in the Cheboygan and the Huron watersheds begin their evolution as relatively dilute solutions dominated by silicate weathering in shallow carbonate-free soil horizons. Here, silicate dissolution is rapid and reaction rates dominantly are controlled by mineral abundances. In the deeper soil horizons, silicate dissolution slows down and soil-water chemistry is dominated by calcite and dolomite weathering, where solutions reach equilibrium with carbonate minerals within the soil profile. Thus, carbonate weathering intensities are dominantly controlled by annual precipitation, temperature and soil pCO 2. Results of a conceptual model support these field observations, implying that dolomite and calcite are dissolving at a similar rate, and further dissolution of more soluble dolomite after calcite equilibrium produces higher dissolved inorganic carbon concentrations and a Mg 2+/Ca 2+ ratio of 0.4. Mass balance calculations show that overall, silicate minerals and atmospheric inputs generally contribute <10% of Ca 2+ and Mg 2+ in natural waters. Dolomite dissolution appears to be a major process

  18. Dynamics of water molecules in glucose solutions.

    SciTech Connect

    Talon, C.; Smith, L. J.; Brady, J. W.; Copley, J. R. D.; Price, D. L.; Saboungi, M. L.; Materials Science Division; Centre de Recherche sur la Matiyre Divisye; Cornell Univ.; NIST; Centre de Recherche sur les Matyriaux y Haute Tempyrature

    2004-04-22

    The effects of the solution of glucose molecules on the dynamics of solvent water have been studied by quasielastic neutron scattering (QENS) measurements on solutions of selectively deuterated glucose in natural water. The data are fitted to two Lorentzians ascribed to pure translational and mixed translational and rotational character, respectively. The addition of the glucose to the water causes a substantial slowing down, by a factor 10 for the translational diffusion and 3-4 for the rotational motion at the highest concentration studied, 1:11 C{sub 6}H{sub 12}O{sub 6}:H{sub 2}O. The values obtained for water diffusion constants are consistent with previous QENS and NMR experiments on monosaccharide solutions but an order of magnitude higher than those derived from a recent molecular dynamics simulation.

  19. Water dynamics in glass ionomer cements

    NASA Astrophysics Data System (ADS)

    Berg, M. C.; Jacobsen, J.; Momsen, N. C. R.; Benetti, A. R.; Telling, M. T. F.; Seydel, T.; Bordallo, H. N.

    2016-07-01

    Glass ionomer cements (GIC) are an alternative for preventive dentistry. However, these dental cements are complex systems where important motions related to the different states of the hydrogen atoms evolve in a confined porous structure. In this paper, we studied the water dynamics of two different liquids used to prepare either conventional or resin-modified glass ionomer cement. By combining thermal analysis with neutron scattering data we were able to relate the water structure in the liquids to the materials properties.

  20. Water dynamics at neutral and ionic interfaces

    PubMed Central

    Fenn, Emily E.; Wong, Daryl B.; Fayer, M. D.

    2009-01-01

    The orientational dynamics of water at a neutral surfactant reverse micelle interface are measured with ultrafast infrared spectroscopy of the hydroxyl stretch, and the results are compared to orientational relaxation of water interacting with an ionic interface. The comparison provides insights into the influence of a neutral vs. ionic interface on hydrogen bond dynamics. Measurements are made and analyzed for large nonionic surfactant Igepal CO-520reverse micelles (water nanopool with a 9-nm diameter). The results are compared with those from a previous study of reverse micelles of the same size formed with the ionic surfactant Aerosol-OT (AOT). The results demonstrate that the orientational relaxation times for interfacial water molecules in the two types of reverse micelles are very similar (13 ps for Igepal and 18 ps for AOT) and are significantly slower than that of bulk water (2.6 ps). The comparison of water orientational relaxation at neutral and ionic interfaces shows that the presence of an interface plays the dominant role in determining the hydrogen bond dynamics, whereas the chemical nature of the interface plays a secondary role. PMID:19706895

  1. Geochemistry, Comparative Analysis, and Physical and Chemical Characteristics of the Thermal Waters East of Hot Springs National Park, Arkansas, 2006-09

    USGS Publications Warehouse

    Kresse, Timothy M.; Hays, Phillip D.

    2009-01-01

    rock collapse for uncased wells completed in highly fractured rock. However, the propagation of newly formed large fractures that potentially could damage well structures or result in pirating of water from production wells appears to be of limited possibility based on review of relevant studies. Characteristics of hydraulic conductivity, storage, and fracture porosity were interpreted from flow rates observed in individual wells completed in the Bigfork Chert and Stanley Shale; from hydrographs produced from continuous measurements of water levels in wells completed in the Arkansas Novaculite, the Bigfork Chert, and Stanley Shale; and from a potentiometric-surface map constructed using water levels in wells throughout the study area. Data gathered from these three separate exercises showed that fracture porosity is much greater in the Bigfork Chert relative to that in the Stanley Shale, shallow groundwater flows from elevated recharge areas with exposures of Bigfork Chert along and into streams within the valleys formed on exposures of the Stanley Shale, and there was no evidence of interbasin transfer of groundwater within the shallow flow system. Fifteen shallow wells and two cold-water springs were sampled from the various exposed formations in the study area to characterize the water quality and geochemistry for the shallow groundwater system and for comparison to the geochemistry of the hot springs in Hot Springs National Park. For the quartz formations (novaculite, chert, and sandstone formations), total dissolved solids concentrations were very low with a median concentration of 23 milligrams per liter, whereas the median concentration for groundwater from the shale formations was 184 milligrams per liter. Ten hot springs in Hot Springs National Park were sampled for the study. Several chemical constituents for the hot springs, including pH, total dissolved solids, major cations and anions, and trace metals, show similarity with the shale formations

  2. ISOGENIE: Linking geochemistry, isotopic chemistry and microbial dynamics & community composition in a thawing permafrost peatland, Stordalen Mire, Abisco, Sweden.

    NASA Astrophysics Data System (ADS)

    Chanton, J.; Crill, P. M.; Rich, V.; McCalley, C. K.; Hodgkins, S. B.; Tyson, G.; Logan, T.; Wehr, R.; Mondav, R.; Li, C.; Frolking, S.; Saleska, S. R.

    2011-12-01

    As permafrost thaws, increasing CH4 emissions from northern wetlands are likely to cause positive feedback to atmospheric warming. One of the over-arching goals of this project is to connect geochemical processes, particularly focusing on methane production, to underlying microbial population dynamics and genomics. Recent transformative technical advances in both high throughput investigations of microbial communities and high temporal resolution biogeochemical isotope measurements now permit a uniquely comprehensive approach to opening the microbial "black boxes" that impact carbon cycling on global scales. This project links detailed microbial sampling with detailed geochemical and isotopic sampling on seasonal and diel timescales and has an extensive modeling component. Gas exchange is monitored across the wetland gradients in a series of automated chambers and isotopes of emitted and belowground methane and carbon dioxide are measured with a QC laser system. The mire is in a state of partial thaw. With this thaw is an apparent ecological session in wetland community structure and associated changes in organic matter lability, rates of methane production and microbial community. Our group's study sites range from palsa with underlying permanently frozen peat, to recently collapsed and flooded palsa, to flooded palsa colonized by Sphagnum, to flooded eriophorum sites, to sites populated by Carex, to open water lakes. Across this environmental gradient pH ranges from 4 to 6.5. This change is driven by changes in hydrology as the surface of the thawing permafrost subsides and an adjacent lake drains into the mire. Along this environmental gradient, from palsa to Carex, the lability of the peat increases significantly as determined in incubations of peat material and monitoring of methane and carbon dioxide production rates. Coincident with this environmental gradient is a decrease in the apparent fractionation factor between methane and carbon dioxide and methane

  3. Aquifer geochemistry and effects of pumping on ground-water quality at the Green Belt Parkway Well Field, Holbrook, Long Island, New York

    USGS Publications Warehouse

    Brown, Craig J.; Colabufo, Steven; Coates, John D.

    2002-01-01

    Geochemistry, microbiology, and water quality of the Magothy aquifer at a new supply well in Holbrook were studied to help identify factors that contribute to iron-related biofouling of public-supply wells. The organic carbon content of borehole sediments from the screen zone, and the dominant terminal electron-accepting processes (TEAPs), varied by depth. TEAP assays of core sediments indicated that iron reduction, sulfate reduction, and undetermined (possibly oxic) reactions and microbial activity are correlated with organic carbon (lignite) content. The quality of water from this well, therefore, reflects the wide range of aquifer microenvironments at this site. High concentrations of dissolved iron (3.6 to 6.4 micromoles per liter) in water samples from this well indicate that some water is derived from Fe(III)-reducing sediments within the aquifer, but traces of dissolved oxygen indicate inflow of shallow, oxygenated water from shallow units that overlie the local confining units. Water-quality monitoring before and during a 2-day pumping test indicates that continuous pumping from the Magothy aquifer at this site can induce downward flow of shallow, oxygenated water despite the locally confined conditions. Average concentrations of dissolved oxygen are high (5.2 milligrams per liter, or mg/L) in the overlying upper glacial aquifer and at the top of the Magothy aquifer (4.3 mg/L), and low (<0.1 mg/L) in the deeper, anaerobic part of the Magothy; average concentrations of phosphate are high (0.4 mg/L) in the upper glacial aquifer and lower (0.008 mg/L) at the top of the Magothy aquifer and in the deeper part of the Magothy (0.013 mg/L). Concentrations of both constituents increased during the 2 days of pumping. The d34S of sulfate in shallow ground water from observation wells (3.8 to 6.4 per mil) was much heavier than that in the supplywell water (-0.1 per mil) and was used to help identify sources of water entering the supply well. The d34S of sulfate in a

  4. Ultrafast vibrational dynamics at water interfaces.

    PubMed

    McGuire, John A; Shen, Y Ron

    2006-09-29

    Time-resolved sum-frequency vibrational spectroscopy permits the study of hitherto neglected ultrafast vibrational dynamics of neat water interfaces. Measurements on interfacial bonded OH stretch modes revealed relaxation behavior on sub-picosecond time scales in close resemblance to that of bulk water. Vibrational excitation is followed by spectral diffusion, vibrational relaxation, and thermalization in the hydrogen-bonding network. Dephasing of the excitation occurs in water molecules surrounded by acetone. PMID:17008527

  5. Dynamics of a space module impacting water

    NASA Astrophysics Data System (ADS)

    Brooks, J. R.; Anderson, L. A.

    1994-05-01

    The dynamic response of a Water Landing Space Module (WLSM) during impact upon water was investigated. A 1/5th-scale model was tested in a water tank and the results were compared with those attained using analytical techniques and computer simulations. A knowledge of the response of the WLSM during impact is necessary to identify design choices that are within the physical limitations of crew members and materials. The purpose of this research was to use simulations to establish trends that occur when the variables of entry speed, angle, and weight are varied. Results suggest which initial conditions of the full-scale WLSM keep impact accelerations under specified limits.

  6. Microbial Sulfur Geochemistry in Mine Systems (Invited)

    NASA Astrophysics Data System (ADS)

    Warren, L. A.; Norlund, K. L.; Hitchcock, A.

    2010-12-01

    Acid mine drainage (AMD), metal laden, acidic water, is the most pressing mining environmental issue on a global scale. While it is well recognized that the activity of autotrophic Fe and S bacteria amplify the oxidation of the sulfidic wastes, thereby generating acidity and leaching metals; the underlying microbial geochemistry is not well described. This talk will highlight results revealing the importance of microbial cooperation associated with a novel sulfur-metabolizing consortium enriched from mine waters. Results generated by an integrated approach, combining field characterization, geochemical experimentation, scanning transmission X-ray microscopy (STXM), and fluorescence in situ hybridization (FISH) [1]describing the underlying ecological drivers, the functionally relevant biogeochemical architecture of the consortial macrostructure as well as the identities of this environmental sulphur redox cycling consortium will be presented. The two common mine bacterial strains involved in this consortium, Acidithiobacillus ferroxidans and Acidiphilium sp., are specifically spatially segregated within a macrostructure (pod) of extracellular polymeric substance (EPS) that enables coupled sulphur oxidation and reduction reactions despite bulk, oxygenated conditions. Identical pod formation by type culture strains was induced and linked to ecological conditions. The proposed sulphur geochemistry associated with this bacterial consortium produces 40-90% less acid than expected based on abiotic AMD models, with implications for both AMD mitigation and AMD carbon flux modeling. We are currently investigating the implications of these sulphur-processing pods for metal dynamics in mine systems. These results demonstrate how microbes can orchestrate their geochemical environment to facilitate metabolism, and underscore the need to consider microbial interactions and ecology in constraining their geochemical impacts. [1] Norlund, Southam, Tyliszcczak, Hu, Karunakaran, Obst

  7. Molecular Dynamics Simulations of Water Evaporation

    NASA Astrophysics Data System (ADS)

    Wen, Chengyuan; Grest, Gary; Cheng, Shengfeng

    2015-03-01

    The evaporation of water from the liquid/vapor interface is studied via large-scale molecular dynamics simulations for systems of more than a million atoms at 550K and 600K. The TIP4P-2005 water model whose liquid/vapor surface tension is in excellent agreement with experiments is used. Evaporative cooling at the interface is observed from temperature profiles determined from both translational and rotational kinetic energy. During evaporation, the density of water is slightly enhanced near the liquid-vapor interface. The velocity distribution of water molecules in the vapor phase during evaporation at various distances relative to the interface fit a Maxwell-Boltzmann distribution. While our results indicate an imbalance between evaporating and condensing water molecules, local thermal equilibrium is found to hold in addition to mechanical equilibrium. Department of Physics, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA.

  8. Geochemistry and origin of formation waters in the western Canada sedimentary basin-I. Stable isotopes of hydrogen and oxygen

    USGS Publications Warehouse

    Hitchon, B.; Friedman, I.

    1969-01-01

    Stable isotopes of hydrogen and oxygen, together with chemical analyses, were determined for 20 surface waters, 8 shallow potable formation waters, and 79 formation waters from oil fields and gas fields. The observed isotope ratios can be explained by mixing of surface water and diagenetically modified sea water, accompanied by a process which enriches the heavy oxygen isotope. Mass balances for deuterium and total dissolved solids in the western Canada sedimentary basin demonstrate that the present distribution of deuterium in formation waters of the basin can be derived through mixing of the diagenetically modified sea water with not more than 2.9 times as much fresh water at the same latitude, and that the movement of fresh water through the basin has redistributed the dissolved solids of the modified sea water into the observed salinity variations. Statistical analysis of the isotope data indicates that although exchange of deuterium between water and hydrogen sulphide takes place within the basin, the effect is minimized because of an insignificant mass of hydrogen sulphide compared to the mass of formation water. Conversely, exchange of oxygen isotopes between water and carbonate minerals causes a major oxygen-18 enrichment of formation waters, depending on the relative masses of water and carbonate. Qualitative evidence confirms the isotopic fractionation of deuterium on passage of water through micropores in shales. ?? 1969.

  9. Dynamical Transition of Protein-Hydration Water

    NASA Astrophysics Data System (ADS)

    Doster, W.; Busch, S.; Gaspar, A. M.; Appavou, M.-S.; Wuttke, J.; Scheer, H.

    2010-03-01

    Thin layers of water on biomolecular and other nanostructured surfaces can be supercooled to temperatures not accessible with bulk water. Chen et al. [Proc. Natl. Acad. Sci. U.S.A. 103, 9012 (2006)]PNASA60027-842410.1073/pnas.0602474103 suggested that anomalies near 220 K observed by quasielastic neutron scattering can be explained by a hidden critical point of bulk water. Based on more sensitive measurements of water on perdeuterated phycocyanin, using the new neutron backscattering spectrometer SPHERES, and an improved data analysis, we present results that show no sign of such a fragile-to-strong transition. The inflection of the elastic intensity at 220 K has a dynamic origin that is compatible with a calorimetric glass transition at 170 K. The temperature dependence of the relaxation times is highly sensitive to data evaluation; it can be brought into perfect agreement with the results of other techniques, without any anomaly.

  10. Water transport dynamics in trees and stands

    SciTech Connect

    Pallardy, S.G.; Cermak, J.; Ewers, F.W.; Kaufmann, M.R.; Parker, W.C.; Sperry, J.S.

    1995-07-01

    Water transport dynamics in trees and stands of conifers have certain features that are characteristic of this group and are at least rare among angiosperms. Among these features is the xylem transport system that is dependent on tracheids for long-distance water transport. Tracheid-containing xylem is relatively inefficient, a property that can reduce submaximum allowable rates of gas exchange, but tracheids also offer substantial capacity for water storage and high resistance to freezing-induced dysfunction. Thus, they are quite compatible with the typical evergreen habit and long transpiration season of conifers. At the stand level, canopy transpiration in conifers is primarily controlled by stomatal conductance. In contrast, in dense canopies of angio-sperms, particularly those of tropical forests with limited air mixing, stand transpiration is limited by radiation input rather than by stomatal control. Because of their evergreen habit a greater proportion of evapotranspiration in conifer forests is associated with evaporation of water intercepted by the tree crowns. Other features of transport dynamics are characteristic of most conifers, but are not unique to this group. Among these features are typically shallow root systems that often must supply water in winter to replace transpiration needs of evergreen species, common occurrence of mycorrhizae that enhance mineral and water uptake, and drought tolerance adaptations that include elements of both dehydration avoidance (e.g., stomatal closure under water stress, shifts in allocation of dry matter to below-ground sinks) and dehydration tolerance (e.g., capacity for acclimation of photosynthetic apparatus to drought, osmotic adjustment). Transpiration rates from conifer foliage often are lower than those of deciduous angiosperms, probably because of the lower maximum capacity of tracheid-bearing xylem to transport water.

  11. Vibrational Spectroscopy and Dynamics of Water.

    PubMed

    Perakis, Fivos; Marco, Luigi De; Shalit, Andrey; Tang, Fujie; Kann, Zachary R; Kühne, Thomas D; Torre, Renato; Bonn, Mischa; Nagata, Yuki

    2016-07-13

    We present an overview of recent static and time-resolved vibrational spectroscopic studies of liquid water from ambient conditions to the supercooled state, as well as of crystalline and amorphous ice forms. The structure and dynamics of the complex hydrogen-bond network formed by water molecules in the bulk and interphases are discussed, as well as the dissipation mechanism of vibrational energy throughout this network. A broad range of water investigations are addressed, from conventional infrared and Raman spectroscopy to femtosecond pump-probe, photon-echo, optical Kerr effect, sum-frequency generation, and two-dimensional infrared spectroscopic studies. Additionally, we discuss novel approaches, such as two-dimensional sum-frequency generation, three-dimensional infrared, and two-dimensional Raman terahertz spectroscopy. By comparison of the complementary aspects probed by various linear and nonlinear spectroscopic techniques, a coherent picture of water dynamics and energetics emerges. Furthermore, we outline future perspectives of vibrational spectroscopy for water researches. PMID:27096701

  12. Geohydrology, water quality, and nitrogen geochemistry in the saturated and unsaturated zones beneath various land uses, Riverside and San Bernardino counties, California, 1991-93

    USGS Publications Warehouse

    Rees, Terry F.; Bright, D.J.; Fay, R.G.; Christensen, A.H.; Anders, R.B.; Baharie, B.S.; Land, M.T.

    1995-01-01

    The U.S. Geological Survey, in cooperation with the Eastern Municipal Water District, the Metropolitan Water District of Southern California, and the Orange County Water District, has completed a derailed study of the Hemet groundwater basin. The quantity of ground water stored in the basin in August 1992 is estimated to be 327,000 acre-feet. Dissolved-solids concentration ranged from 380 to 700 mg/L (milligrams per liter), except in small areas where the concentration exceeded 1,000 mg/L. Nitrate concentrations exc__*'ded the U.S. Environmental Protection Agency Maximum Contaminant Level (MCL) of 10 mg/L nitrate (its nitrogen) in the southeastern part of the basin, in the Domenigoni Valley area, and beneath a dairy in the Diamond Valley area. Seven sites representing selected land uses-residential, tuff grass irrigated with reclaimed water, citrus grove, irrigated farm, poultry farm, and dairy (two sites)--were selected for detailed study of nitrogen geochemistry in the unsaturated zone. For all land uses, nitrate was the dominant nitrogen species in the unsaturated zone. Although nitrate was seasonally present in the shallow unsaturated zone beneath the residential site, it was absent at moderate depths, suggesting negligible migration of nitrate from the surface at this time. Microbial denitrification probably is occurring in the shallow unsaturated zone. High nitrate concentrations in the deep unsaturated zone (greater than 100 ft) suggest either significantly higher nitrate loading at some time in the past, or lateral movement of nitrate at depth. Nitrate also is seasonally present in the shallow unsaturated zone beneath the reclaimed-water site, and (in contrast with the residential site), nitrate is perennially present in the deeper unsaturated zone. Mictobial identification in the unsaturated zone and in the capillary fringe above the water table decreases, the concentrations of nitrate in pore water to below the MCL before reaching the water table. Pore

  13. Water dynamics in different biochar fractions.

    PubMed

    Conte, Pellegrino; Nestle, Nikolaus

    2015-09-01

    Biochar is a carbonaceous porous material deliberately applied to soil to improve its fertility. The mechanisms through which biochar acts on fertility are still poorly understood. The effect of biochar texture size on water dynamics was investigated here in order to provide information to address future research on nutrient mobility towards plant roots as biochar is applied as soil amendment. A poplar biochar has been stainless steel fractionated in three different textured fractions (1.0-2.0 mm, 0.3-1.0 mm and <0.3 mm, respectively). Water-saturated fractions were analyzed by fast field cycling (FFC) NMR relaxometry. Results proved that 3D exchange between bound and bulk water predominantly occurred in the coarsest fraction. However, as porosity decreased, water motion was mainly associated to a restricted 2D diffusion among the surface-site pores and the bulk-site ones. The X-ray μ-CT imaging analyses on the dry fractions revealed the lowest surface/volume ratio for the coarsest fraction, thereby corroborating the 3D water exchange mechanism hypothesized by FFC NMR relaxometry. However, multi-micrometer porosity was evidenced in all the samples. The latter finding suggested that the 3D exchange mechanism cannot even be neglected in the finest fraction as previously excluded only on the basis of NMR relaxometry results. X-ray μ-CT imaging showed heterogeneous distribution of inorganic materials inside all the fractions. The mineral components may contribute to the water relaxation mechanisms by FFC NMR relaxometry. Further studies are needed to understand the role of the inorganic particles on water dynamics. PMID:25594163

  14. Evidence for the control of river-water chemical stratification on the geochemistry of Amazonian floodplain sediments

    NASA Astrophysics Data System (ADS)

    Roddaz, Martin; Viers, Jérôme; Moreira-Turcq, Patricia; Blondel, Camille; Sontag, Francis; Guyot, Jean-Loup; Moreira, Luciane

    2014-05-01

    Holocene and historical Amazonian floodplain deposits collected from two cores of the Varzea Curuai flooded area (Brazil) were analysed for major and trace element geochemistry as well as Nd-Sr isotopic compositions (21 samples). The TA11 and TA14 cores (110 cm and 270 cm in depth, respectively) were collected at different locations in the varzea, near a channel inlet connecting the Amazon River to the varzea and at the centre of the varzea, respectively. The two cores represent records of sedimentation on different time-scales, with TA11 covering the last 100 years and TA14 extending back to 5600 years cal BP. Although the sediments are generally coarser in TA11 than in TA14, the major and trace element concentrations, Cr/Th and Th/Sc and Eu anomalies and Nd-Sr isotopic compositions in both cores fail to show any clear variations with depth. However, there are some chemical differences between the two analysed cores. The TA14 sediments have higher Al/Si and CIA values than those of TA11. The TA14 sediments are enriched in Th, U, Y, Nb, REE, Cs, Rb, V and Ni but show slightly depleted MgO, CaO and Sr and more strongly depleted Na2O, Zr and Hf compared with TA11. In addition, the Nd-Sr isotopic compositions of the TA11 sediment core are on the whole similar to the Solimões suspended particulate matter (SPM), whereas TA14 has a similar Nd-Sr isotopic composition compared with the SPM of the Amazon River at Obidos. These differences are best explained by chemical stratification of the Amazon River. During flooding of the Amazon River, coarser grained particulates supplied by the Solimões River are deposited in the deepest environments near the channel inlet, as recorded in the TA11 sediment core. By contrast, finer grained suspended sediments derived from the Madeira River are transported into the shallower environments of the varzea system and deposited as a result of flow expansion and loss of carrying power, as recorded in the TA14 sediment core. We calculate

  15. Photonic water dynamically responsive to external stimuli.

    PubMed

    Sano, Koki; Kim, Youn Soo; Ishida, Yasuhiro; Ebina, Yasuo; Sasaki, Takayoshi; Hikima, Takaaki; Aida, Takuzo

    2016-01-01

    Fluids that contain ordered nanostructures with periodic distances in the visible-wavelength range, anomalously exhibit structural colours that can be rapidly modulated by external stimuli. Indeed, some fish can dynamically change colour by modulating the periodic distance of crystalline guanine sheets cofacially oriented in their fluid cytoplasm. Here we report that a dilute aqueous colloidal dispersion of negatively charged titanate nanosheets exhibits structural colours. In this 'photonic water', the nanosheets spontaneously adopt a cofacial geometry with an ultralong periodic distance of up to 675 nm due to a strong electrostatic repulsion. Consequently, the photonic water can even reflect near-infrared light up to 1,750 nm. The structural colour becomes more vivid in a magnetic flux that induces monodomain structural ordering of the colloidal dispersion. The reflective colour of the photonic water can be modulated over the entire visible region in response to appropriate physical or chemical stimuli. PMID:27572806

  16. A peptide's perspective of water dynamics.

    PubMed

    Ghosh, Ayanjeet; Hochstrasser, Robin M

    2011-11-18

    This Perspective is focused on amide groups of peptides interacting with water. The 2D IR spectroscopy has already enabled structural aspects of the peptide backbone to be determined through its ability to measure the coupling between different amide-I modes. Here we describe why nonlinear IR is emerging as the method of choice to examine the fast components of the water dynamics near peptides and how isotopically edited peptide links can be used to probe the local water at a residue level in proteins. This type of research necessarily involves an intimate mix of theory and experiment. The description of the results is underpinned by relatively well established quantum-statistical theories that describe the important manifestations of peptide vibrational frequency fluctuations. PMID:22844177

  17. A peptide's perspective of water dynamics

    PubMed Central

    Ghosh, Ayanjeet; Hochstrasser, Robin M.

    2012-01-01

    This Perspective is focused on amide groups of peptides interacting with water. The 2D IR spectroscopy has already enabled structural aspects of the peptide backbone to be determined through its ability to measure the coupling between different amide-I modes. Here we describe why nonlinear IR is emerging as the method of choice to examine the fast components of the water dynamics near peptides and how isotopically edited peptide links can be used to probe the local water at a residue level in proteins. This type of research necessarily involves an intimate mix of theory and experiment. The description of the results is underpinned by relatively well established quantum-statistical theories that describe the important manifestations of peptide vibrational frequency fluctuations. PMID:22844177

  18. Geohydrology, Geochemistry, and Ground-Water Simulation-Optimization of the Central and West Coast Basins, Los Angeles County, California

    USGS Publications Warehouse

    Reichard, Eric G.; Land, Michael; Crawford, Steven M.; Johnson, Tyler D.; Everett, Rhett; Kulshan, Trayle V.; Ponti, Daniel J.; Halford, Keith L.; Johnson, Theodore A.; Paybins, Katherine S.; Nishikawa, Tracy

    2003-01-01

    Historical ground-water development of the Central and West Coast Basins in Los Angeles County, California through the first half of the 20th century caused large water-level declines and induced seawater intrusion. Because of this, the basins were adjudicated and numerous ground-water management activities were implemented, including increased water spreading, construction of injection barriers, increased delivery of imported water, and increased use of reclaimed water. In order to improve the scientific basis for these water management activities, an extensive data collection program was undertaken, geohydrological and geochemical analyses were conducted, and ground-water flow simulation and optimization models were developed. In this project, extensive hydraulic, geologic, and chemical data were collected from new multiple-well monitoring sites. On the basis of these data and data compiled and collected from existing wells, the regional geohydrologic framework was characterized. For the purposes of modeling, the three-dimensional aquifer system was divided into four aquifer systems?the Recent, Lakewood, Upper San Pedro, and Lower San Pedro aquifer systems. Most pumpage in the two basins is from the Upper San Pedro aquifer system. Assessment of the three-dimensional geochemical data provides insight into the sources of recharge and the movement and age of ground water in the study area. Major-ion data indicate the chemical character of water containing less than 500 mg/L dissolved solids generally grades from calcium-bicarbonate/sulfate to sodium bicarbonate. Sodium-chloride water, high in dissolved solids, is present in wells near the coast. Stable isotopes of oxygen and hydrogen provide information on sources of recharge to the basin, including imported water and water originating in the San Fernando Valley, San Gabriel Valley, and the coastal plain and surrounding hills. Tritium and carbon-14 data provide information on relative ground-water ages. Water with

  19. Coal Formation and Geochemistry

    NASA Astrophysics Data System (ADS)

    Orem, W. H.; Finkelman, R. B.

    2003-12-01

    Coal is one of the most complex and challenging natural materials to analyze and to understand. Unlike most rocks, which consist predominantly of crystalline mineral grains, coal is largely an assemblage of amorphous, degraded plant remains metamorphosed to various degrees and intermixed with a generous sprinkling of minute syngenetic, diagenetic, epigenetic, and detrital mineral grains, and containing within its structure various amounts of water, oils, and gases. Each coal is unique, having been derived from different plant sources over geologic time, having experienty -45ced different thermal histories, and having been exposed to varying geologic processes. This diversity presents a challenge to constructing a coherent picture of coal geochemistry and the processes that influence the chemical composition of coal.Despite the challenge coal presents to geochemists, a thorough understanding of the chemistry and geology of this complex natural substance is essential because of its importance to our society. Coal is, and will remain for sometime, a crucial source of energy for the US and for many other countries (Figure 1). In the USA, more than half of the electricity is generated by coal-fired power plants, and almost 90% of the coal mined in the USA is sold for electricity generation (Pierce et al., 1996). It is also an important source of coke for steel production, chemicals, pharmaceuticals, and even perfumes ( Schobert, 1987). It may also, in some cases, be an economic source of various mineral commodities. The utilization of coal through mining, transport, storage, combustion, and the disposal of the combustion by-products, also presents a challenge to geochemists because of the wide range of environmental and human health problems arising from these activities. The sound and effective use of coal as a natural resource requires a better understanding of the geochemistry of coal, i.e., the chemical and mineralogical characteristics of the coal that control its

  20. Geochemistry of batch-extract waters derived from spoil material collected at the Cordero coal mine, Powder River basin, Wyoming

    USGS Publications Warehouse

    Naftz, D.L.

    1990-01-01

    Batch-mixing experiments to evaluate postmining water quality at the Cordero Mine were conducted by the U.S. Geological Survey during 1984 to 1985. Contact of groundwater from the spoil aquifer with fresh spoil material caused only small changes in major-element concentrations and in pH, unless sulfide oxidation or contact with soluble salts, such as epsomite, occurred. In contrast, large changes in major-element concentration resulted when water from the coal aquifer contacted the spoil material. Only three of seven reaction models considered to explain the water quality changes during the batch-mixing experiments were consistent with the thermodynamic and mineralogical data. The three models used to account for the observed water quality changes derived potassium from potassium feldspar; magnesium from chlorite or epsomite or both; sodium from cation exchange and halite; chloride from halite; silica from potassium feldspar and chlorite; sulfate from gypsum, or epsomite or both, and carbon from carbon dioxide. In general, water quality samples obtained from the batch-mixing experiments using water from the coal aquifer had smaller major-ion concentrations than the actual water quality in the spoil aquifer. These differences can be explained by the limited amount of efflorescent salt dissolution and volume of water used in the experiments. Correction ratios calculated for these experiments may be applied to batch-mixing experiments at other mines in the area, to predict postmining water quality. (USGS)

  1. Interstitial Water Geochemistry and Low Temperature Alteration in Volcaniclastic Sediments from the Amami Sankaku Basin at IODP Site U1438 (Expedition 351)

    NASA Astrophysics Data System (ADS)

    Loudin, L. C.; Yogodzinski, G. M.; Sena, C.; van der Land, C.; Zhang, Z.; Marsaglia, K. M.; Meffre, S.

    2014-12-01

    Interstitial water (IW) geochemistry provides insight into the diagenetic transformation of sediment to rock by component dissolution/alteration and precipitation of new mineral phases as pore-filling cements, as well as providing insight into ion exchange reactions with secondary minerals. At Site U1438, 67 IW samples were collected within a ~950 m section of volcaniclastic sediments. These were analyzed for pH as well as major and trace elements. The corresponding host sediments were mineralogically characterized by XRD and petrographic observations. Three alteration zones are inferred: 1) the upper alteration zone (~0-300 mbsf) characterized by maximum IW concentrations of Si (790.1 μM), Sr (138.5 μM) and Mn (279.5 μM), consistent with volcanic glass and siliceous microfossil dissolution, enhanced reduction of Mn oxides, and carbonate recrystallization. Maximum concentrations in Li and B coupled with the lowest pH (6.7) imply that Li and B are released into the IW due to silicate dissolution and clay desorption. 2) At intermediate depths (~300 to ~550 mbsf) Mg, K, Sr, Si, Mn, Li, and B are at concentration minima, possibly due to growth of authigenic minerals. B and Li minimum concentrations occur at high pH (~9) suggesting that these elements are preferentially removed from high pH waters during the precipitation of clay mineral and zeolite cements in primary and secondary (dissolution) pores. The mineralogy of these phases is confirmed by XRD data, and their pore-filling nature is seen in thin sections of the coarser lithologies. 3) The deep alteration zone (>~550m) is characterized by an increase in B, Li, Sr and Ca. At ~650 mbsf, Ca becomes the dominant cation in solution consistent with either mineral interaction with the IW, or diffusive input from underlying igneous basement (~1400 mbsf).

  2. Dynamic Coupling of Iron, Manganese, and Phosphorus Behavior in Water and Sediment of Shallow Ice-Covered Eutrophic Lakes.

    PubMed

    Schroth, Andrew W; Giles, Courtney D; Isles, Peter D F; Xu, Yaoyang; Perzan, Zachary; Druschel, Gregory K

    2015-08-18

    Decreasing duration and occurrence of northern hemisphere ice cover due to recent climate warming is well-documented; however, biogeochemical dynamics underneath the ice are poorly understood. We couple time-series analyses of water column and sediment water interface (SWI) geochemistry with hydrodynamic data to develop a holistic model of iron (Fe), manganese (Mn), and phosphorus (P) behavior underneath the ice of a shallow eutrophic freshwater bay. During periods of persistent subfreezing temperatures, a highly reactive pool of dissolved and colloidal Fe, Mn, and P develops over time in surface sediments and bottom waters due to reductive dissolution of Fe/Mn(oxy)hydroxides below the SWI. Redox dynamics are driven by benthic O2 consumption, limited air-water exchange of oxygen due to ice cover, and minimal circulation. During thaw events, the concentration, distribution and size partitioning of all species changes, with the highest concentrations of P and "truly dissolved" Fe near the water column surface, and a relatively well-mixed "truly dissolved" Mn and "colloidal" Fe profile due to the influx of geochemically distinct river water and increased circulation. The partitioning and flux of trace metals and phosphorus beneath the ice is dynamic, and heavily influenced by climate-dependent physical processes that vary in both time and space. PMID:26206098

  3. Geochemistry of thermal/mineral waters in the Clear Lake region, California, and implications for hot dry rock geothermal development

    SciTech Connect

    Goff, F.; Adams, A.I.; Trujillo, P.E.; Counce, D.; Mansfield, J.

    1993-02-01

    Thermal/mineral waters of the Clear Lake region are broadly classified as thermal meteoric and connote types based on chemical and isotopic criteria. Ratios of conservative components such as B/Cl are extremely different among all thermal/mineral waters of the Clear Lake region except for clusters of waters emerging from specific areas such as the Wilbur Springs district and the Agricultural Park area south of Mt. Konocti. In contrast, ratios of conservative components in large, homogeneous geothermal reservoirs are constant. Stable isotope values of Clear Lake region waters show a mixing trend between thermal meteoric and connote end-members. The latter end-member has enriched [delta]D as well as enriched d[sup l8]O, very different from typical high-temperature geothermal reservoir waters. Tritium data and modeling of ages indicate most Clear Lake region waters are 500 to > 10,000 yr., although mixing of old and young components is implied by the data. The age of end-member connate water is probably > 10,000 yr. Subsurface equilibration temperature of most thermal/mineral waters of the Clear Lake region is [le] 150[degrees]C based on chemical geothermometers but it is recognized that Clear Lake region waters are not typical geothermal fluids and that they violate rules of application of many geothermometers. The combined data indicate that no large geothermal reservoir underlies the Clear Lake region and that small localized reservoirs have equilibration temperatures [le] 150[degrees]C (except for Sulphur Bank Mine). Hot dry rock technologies are the best way to commercially exploit the known high temperatures existing beneath the Clear Lake region, particularly within the main Clear Lake volcanic field.

  4. Water drop dynamics on a granular layer

    NASA Astrophysics Data System (ADS)

    Llorens, Coraline; Biance, Anne-Laure; Ybert, Christophe; Pirat, Christophe; Liquids; Interfaces Team

    2015-11-01

    Liquid drop impacts, either on a solid surface or a liquid bath, have been studied for a while and are still subject of intense research. Less is known concerning impacts on granular layers that are shown to exhibit an intermediate situation between solid and liquid. In this study, we focus on water drop impacts on granular matter made of micrometer-sized spherical glass beads. In particular, we investigate the overall dynamics arising from the interplay between liquid and grains throughout the impact. Depending on the relevant parameters (impact velocity, drop and grain sizes, as well as their wetting properties), various behaviors are evidenced. In particular, the behavior of the beads at the liquid-gas interface (ball-bearing vs imbibition) is shown to greatly affect the spreading dynamics of the drop, as well as satellite droplets formation, beads ejection, and the final crater morphology.

  5. Structure and dynamics of amorphous water ice

    NASA Technical Reports Server (NTRS)

    Laufer, D.; Kochavi, E.; Bar-Nun, A.; Owen, T. (Principal Investigator)

    1987-01-01

    Further insight into the structure and dynamics of amorphous water ice, at low temperatures, was obtained by trapping in it Ar, Ne, H2, and D2. Ballistic water-vapor deposition results in the growth of smooth, approximately 1 x 0.2 micrometer2, ice needles. The amorphous ice seems to exist in at least two separate forms, at T < 85 K and at 85 < T < 136.8 K, and transform irreversibly from one form to the other through a series of temperature-dependent metastable states. The channels formed by the water hexagons in the ice are wide enough to allow the free penetration of H2 and D2 into the ice matrix even in the relatively compact cubic ice, resulting in H2-(D2-) to-ice ratios (by number) as high as 0.63. The larger Ar atoms can penetrate only into the wider channels of amorphous ice, and Ne is an intermediate case. Dynamic percolation behavior explains the emergence of Ar and Ne (but not H2 and D2) for the ice, upon warming, in small and big gas jets. The big jets, each containing approximately 5 x 10(10) atoms, break and propel the ice needles. Dynamic percolation also explains the collapse of the ice matrix under bombardment by Ar , at a pressure exceeding 2.6 dyn cm-2, and the burial of huge amounts of gas inside the collapsed matrix, up to an Ar-to-ice of 3.3 (by number). The experimental results could be relevant to comets, icy satellites, and icy grain mantles in dense interstellar clouds.

  6. The effect of weathering in the Buyukmelen River basin on the geochemistry of suspended and bed sediments and the hyrogeochemical characteristics of river water, Duzce, Turkey

    NASA Astrophysics Data System (ADS)

    Pehlivan, Rustem

    2010-07-01

    The Buyukmelen River is expected to be a water source that can supply the drinking water needs of Istanbul until 2040. The drinking and utility water needs of Istanbul are to transport water from the Buyukmelen River to Istanbul via pipeline and pump it into the Alibeykoy and Omerli reservoirs when their water levels drop. The Buyukmelen River is located in the province of Duzce in 170 km east of Istanbul and its water basin is approximately 2250 km 2. The Buyukmelen River flows muddy in the rainy season and into the Black Sea. The chemical compositions of natural waters alter due to interaction with geological formations, physical and chemical weathering of various rocks and the effects of mining and agricultural production. A research was conducted at the Buyukmelen River basin to determine the effects of hydrological processes. Therefore, the samples of rocks, soil, stream water, suspended and bed sediment were collected from the Buyukmelen River basin. Geochemical and water chemistry analyses of samples were performed at ALS Chemex laboratories, Canada. The bed sediments contain quartz, calcite, plagioclase, amphibole and clay minerals. The clay minerals in the suspended and bed sediment samples are kaolinite, smectite and illite. The water samples collected from the Aksu, Kucukmelen, Asarsu and Ugursuyu streams and the Buyukmelen River in winter (December 2005) and summer (June 2006) periods are rich in Ca and HCO 3 ions. The ions most abundant in rainfall sample are HCO 3 and Na. The ion compositions of surface waters have increased due to the weathering of limestone, agglomerate and volcanic sandstones, light acidic rainfall, semi-arid Black Sea climate in the Buyukmelen basin. The suspended sediment amount of the Buyukmelen River in the rainy season (December 2005) is 174 mg/l. According to the water contamination regulation of Turkey, the Buyukmelen Rivers belongs to quality class 4 based on Al ion and to quality class 3 based on Fe ion in winter period

  7. Polarizable water model for Dissipative Particle Dynamics

    NASA Astrophysics Data System (ADS)

    Pivkin, Igor; Peter, Emanuel

    2015-11-01

    Dissipative Particle Dynamics (DPD) is an efficient particle-based method for modeling mesoscopic behavior of fluid systems. DPD forces conserve the momentum resulting in a correct description of hydrodynamic interactions. Polarizability has been introduced into some coarse-grained particle-based simulation methods; however it has not been done with DPD before. We developed a new polarizable coarse-grained water model for DPD, which employs long-range electrostatics and Drude oscillators. In this talk, we will present the model and its applications in simulations of membrane systems, where polarization effects play an essential role.

  8. Geochemistry of dissolved trace elements and heavy metals in the Dan River Drainage (China): distribution, sources, and water quality assessment.

    PubMed

    Meng, Qingpeng; Zhang, Jing; Zhang, Zhaoyu; Wu, Tairan

    2016-04-01

    Dissolved trace elements and heavy metals in the Dan River drainage basin, which is the drinking water source area of South-to-North Water Transfer Project (China), affect large numbers of people and should therefore be carefully monitored. To investigate the distribution, sources, and quality of river water, this study integrating catchment geology and multivariate statistical techniques was carried out in the Dan River drainage from 99 river water samples collected in 2013. The distribution of trace metal concentrations in the Dan River drainage was similar to that in the Danjiangkou Reservoir, indicating that the reservoir was significantly affected by the Dan River drainage. Moreover, our results suggested that As, Sb, Cd, Mn, and Ni were the major pollutants. We revealed extremely high concentrations of As and Sb in the Laoguan River, Cd in the Qingyou River, Mn, Ni, and Cd in the Yinhua River, As and Sb in the Laojun River, and Sb in the Dan River. According to the water quality index, water in the Dan River drainage was suitable for drinking; however, an exposure risk assessment model suggests that As and Sb in the Laojun and Laoguan rivers could pose a high risk to humans in terms of adverse health and potential non-carcinogenic effects. PMID:26782327

  9. Application of cluster analysis to the geochemistry zonation of the estuary waters in the Tinto and Odiel rivers (Huelva, Spain).

    PubMed

    Grande, José Antonio; Borrego, José; de la Torre, Maria Luisa; Sáinz, A

    2003-06-01

    The combination of acid water from mines, industrial effluents and sea water plays a determining role in the evolutionary process of the chemical makeup of the water in the estuary of the Tinto and Odiel rivers. This estuary is in the southwest of the Iberian Peninsula and is one of the estuarine systems on the northwest coast of the Gulf of Cádiz. From the statistical treatment of data obtained by analyzing samples of water from this system, which is affected by industrial and mining pollution processes, we can see how the sampling points studied form two large groups depending on whether they receive tidal or fluvial influences. Fluvial input contributes acid water with high concentrations of heavy metal, whereas industrial effluents are responsible for the presence of phosphates, silica and other nutrients. The estuarine system of the Tinto and Odiel Rivers can be divided into three areas--the Tinto estuary, the Odiel estuary and the area of confluence--based on the physical--chemical characteristics of the water. PMID:12901168

  10. Questa Baseline and Pre-Mining Ground-Water Quality Investigation. 25. Summary of Results and Baseline and Pre-Mining Ground-Water Geochemistry, Red River Valley, Taos County, New Mexico, 2001-2005

    USGS Publications Warehouse

    Nordstrom, D. Kirk

    2008-01-01

    -sediment chemistry; geomorphology and its effect on ground-water flow; geophysical studies on depth to ground-water table and depth to bedrock; bedrock fractures and their potential influence on ground-water flow; leaching studies of scars and waste-rock piles; mineralogy and mineral chemistry and their effect on ground-water quality; debris-flow hazards; hydrology and water balance for the Red River Valley; ground-water geochemistry of selected wells undisturbed by mining in the Red River Valley; and quality assurance and quality control of water analyses. Studies aimed specifically at the Straight Creek natural-analog site include electrical surveys; high-resolution seismic survey; age-dating with tritium/helium; water budget; ground-water hydrology and geochemistry; and comparison of mineralogy and lithology to that of the mine site. The highly mineralized and hydrothermally altered volcanic rocks of the Red River Valley contain several percent pyrite in the quartz-sericite-pyrite (QSP) alteration zone, which weather naturally to acid-sulfate surface and ground waters that discharge to the Red River. Weathering of waste-rock piles containing pyrite also contributes acid water that eventually discharges into the Red River. These acid discharges are neutralized by circumneutral-pH, carbonate-buffered surface and ground waters of the Red River. The buffering capacity of the Red River, however, decreases from the town of Red River to the U.S. Geological Survey (USGS) gaging station near Questa. During short, but intense, storm events, the buffering capacity is exceeded and the river becomes acid from the rapid flushing of acidic materials from natural scar areas. The lithology, mineralogy, elevation, and hydrology of the Straight Creek proximal analog site were found to closely approximate those of the mine site with the exception of the mine site?s Sulphur Gulch catchment. Sulphur Gulch contains three subcatchments?upper Sulphur Gulch, Blind Gulch, and Spring Gulc

  11. Hydrogeochemical evolution of inland lakes’ water: A study of major element geochemistry in the Wadi El Raiyan depression, Egypt

    PubMed Central

    Mohamed, Essam A.; El-Kammar, Ahmed M.; Yehia, Mohamed M.; Abu Salem, Hend S.

    2015-01-01

    Wadi El Raiyan is a great depression located southwest of Cairo in the Western Desert of Egypt. Lake Qarun, located north of the study area, is a closed basin with a high evaporation rate. The source of water in the lake is agricultural and municipal drainage from the El Faiyum province. In 1973, Wadi El Raiyan was connected with the agricultural wastewater drainage system of the Faiyum province and received water that exceeded the capacity of Lake Qarun. Two hydrogeological regimes have been established in the area: (i) higher cultivated land and (ii) lower Wadi El Raiyan depression lakes. The agricultural drainage water of the cultivated land has been collected in one main drain (El Wadi Drain) and directed toward the Wadi El Raiyan depression, forming two lakes at different elevations (upper and lower). In the summer of 2012, the major chemical components were studied using data from 36 stations distributed over both hydrogeological regimes in addition to one water sample collected from Bahr Youssef, the main source of freshwater for the Faiyum province. Chemical analyses were made collaboratively. The major ion geochemical evolution of the drainage water recharging the El Raiyan depression was examined. Geochemically, the Bahr Youssef sample is considered the starting point in the geochemical evolution of the studied surface water. In the cultivated area, major-ion chemistry is generally influenced by chemical weathering of rocks and minerals that are associated with anthropogenic inputs, as well as diffuse urban and/or agricultural drainage. In the depression lakes, the water chemistry generally exhibits an evaporation-dependent evolutionary trend that is further modified by cation exchange and precipitation of carbonate minerals. PMID:26644942

  12. THE INTERIOR DYNAMICS OF WATER PLANETS

    SciTech Connect

    Fu, Roger; O'Connell, Richard J.; Sasselov, Dimitar D. E-mail: richard_oconnell@harvard.ed

    2010-01-10

    The ever-expanding catalog of detected super-Earths calls for theoretical studies of their properties in the case of a substantial water layer. This work considers such water planets with a range of masses and water mass fractions (2-5 M{sub Earth}, 0.02%-50% H{sub 2}O). First, we model the thermal and dynamical structure of the near-surface for icy and oceanic surfaces, finding separate regimes where the planet is expected to maintain a subsurface liquid ocean and where it is expected to exhibit ice tectonics. Newly discovered exoplanets may be placed into one of these regimes given estimates of surface temperature, heat flux, and gravity. Second, we construct a parameterized convection model for the underlying ice mantle of higher ice phases, finding that materials released from the silicate-iron core should traverse the ice mantle on the timescale of 0.1 to 100 megayears. We present the dependence of the overturn times of the ice mantle and the planetary radius on total mass and water mass fraction. Finally, we discuss the implications of these internal processes on atmospheric observables.

  13. Observing Global Surface Water Flood Dynamics

    NASA Astrophysics Data System (ADS)

    Bates, Paul D.; Neal, Jefferey C.; Alsdorf, Douglas; Schumann, Guy J.-P.

    2014-05-01

    Flood waves moving along river systems are both a key determinant of globally important biogeochemical and ecological processes and, at particular times and particular places, a major environmental hazard. In developed countries, sophisticated observing networks and ancillary data, such as channel bathymetry and floodplain terrain, exist with which to understand and model floods. However, at global scales, satellite data currently provide the only means of undertaking such studies. At present, there is no satellite mission dedicated to observing surface water dynamics and, therefore, surface water scientists make use of a range of sensors developed for other purposes that are distinctly sub-optimal for the task in hand. Nevertheless, by careful combination of the data available from topographic mapping, oceanographic, cryospheric and geodetic satellites, progress in understanding some of the world's major river, floodplain and wetland systems can be made. This paper reviews the surface water data sets available to hydrologists on a global scale and the recent progress made in the field. Further, the paper looks forward to the proposed NASA/CNES Surface Water Ocean Topography satellite mission that may for the first time provide an instrument that meets the needs of the hydrology community.

  14. Mine water geochemistry and metal flux in a major historic Pb-Zn-F orefield, the Yorkshire Pennines, UK.

    PubMed

    Jones, A; Rogerson, M; Greenway, G; Potter, H A B; Mayes, W M

    2013-11-01

    Recent studies have shown up to 6 % of rivers in England and Wales to be impacted by discharges from abandoned metal mines. Despite the large extent of impacts, there are still many areas where mine water impact assessments are limited by data availability. This study provides an overview of water quality, trace element composition and flux arising from one such area; the Yorkshire Pennine Orefield in the UK. Mine drainage waters across the orefield are characterised by Ca-HCO3-SO4-type waters, with moderate mineralization (specific electrical conductance: 160-525 μS cm(-1)) and enrichment of dissolved Zn (≤2003 μg L(-1)), Ba (≤971 μg L(-1)), Pb (≤183 μg L(-1)) and Cd (≤12 μg L(-1)). The major ion composition of the waters reflects the Carboniferous gritstone and limestone-dominated country rock, the latter of which is heavily karstified in parts of the orefield, while sulphate and trace element enrichment is a product of the oxidation of galena, sphalerite and barite mineralization. Contaminant flux measurements at discharge sites highlight the disproportionate importance of large drainage levels across the region, which generally discharge into first-order headwater streams. Synoptic metal loading surveys undertaken in the Hebden Beck sub-catchment of the river Wharfe highlight the importance of major drainage levels to instream baseflow contamination, with diffuse sources from identifiable expanses of waste rock becoming increasingly prominent as river flows increase. PMID:23386384

  15. Effects of sediment depositional environment and ground-water flow on the quality and geochemistry of water in aquifers in sediments of Cretaceous age in the coastal plain of South Carolina

    USGS Publications Warehouse

    Speiran, Gary K.; Aucott, Walter R.

    1994-01-01

    The quality and geochemistry of ground water are significantly affected by the depositional environment of aquifer sediments. Cretaceous sediments in the Coastal Plain of South Carolina have been deposited in fluvial, delta-plain, marginal-marine, and marine environments. Depositional environments of sediments within a single aquifer may grade from nonmarine, fluvial, or upper delta plain near the updip limit of the aquifer to transitional, lower delta plain and to marine toward the coast. In nonmarine sediments the major source of inorganic carbon in the water is the decomposition of organic material. The major aqueous geochemical processes are the dissolution and alteration of silicate minerals. Silica makes up a major part of the dissolved constituents in water from these sediments. In transitional and marine sediments the major aqueous geochemical processes are (1) the dissolution of calcium carbonate by hydrolysis and by carbonic acid derived from the decomposition of organic material and (2) the exchange of calcium in solution for sodium on the marine-clay minerals. The clay minerals may also serve as buffers by neutralizing the hydroxyl ion produced by hydrolysis. The effects of incompletely flushed dilute saltwater on water quality increase toward the coast and toward the northeast.

  16. The geochemistries of 210Po and 210Pb in waters overlying and within the Orca Basin, Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Todd, James F.; Wong, George T. F.; Reid, David F.

    1986-10-01

    Vertical profiles of dissolved 210Po, 210Pb, and 226Ra were obtained from waters overlying and within the Orca Basin; an anoxic, hypersaline and virtually non-sulfide bearing basin in the Gulf of Mexico. The station had a depth of 2410 m. The seawater-brine interface was located at 2230 m. In oxic waters, near-surface (0-250 m) concentrations of dissolved 210Po and 210Pb ranged from 6 to 8 dpm/100 kg and decreased to about 3 dpm/100 kg at 740 m. Below this depth concentrations remained relatively constant. Near-surface 226Ra concentrations varied from about 7 to 9 dpm/100 kg, and then increased with depth to a relatively uniform deep-water value of approximately 13 dpm/100 kg, in agreement with previously reported data for the Gulf of Mexico. The slight deficiency of 210Pb in the surface waters may result from mixing with inner shelf waters that are enriched in 226Ra. At the seawater-brine interface, sharp maxima were observed in the profiles of 210Po, 210Pb, and 226Ra, where concentrations reached 56.0, 28.3, and 840 dpm/100 kg, respectively. These are among the highest values reported for the marine environment to date. Below the interface, concentrations decreased to about 9, 6, and 210 dpm/100 kg for 210Po, 210Pb, and 226Ra, respectively. These sharp maxima may be caused by a combination of the accumulation of particles in the strong pycnocline, the subsequent dissolution of particulate hydrous Mn and Fe oxides and hydroxides, and the decomposition of biogenic particulate material. The residence time of 210Pb in the brine is about one year, a value similar to that reported for the anoxic waters of the Cariaco Trench even though the concentration of 210Pb in that basin is much lower.

  17. Geochemistry of pore waters from Shell Oil Company drill holes on the continental slope of the northern Gulf of Mexico

    USGS Publications Warehouse

    Manheim, F. T.; Bischoff, J.L.

    1969-01-01

    Pore waters were analyzed from 6 holes drilled from M.V. "Eureka" as a part of the Shell Oil Co. deeper offshore study. The holes were drilled in water depths of 600-3,000 ft. (approximately 180-550 m) and penetrated up to 1,000 ft. (300 m) of Pliocene-Recent clayey sediments. Salt and anhydrite caprock was encountered in one diapiric structure on the continental slope. Samples from holes drilled near diapiric structures showed systematic increases of pore-water salinity with depth, suggestive of salt diffusion from underlying salt plugs. Anomalous concentrations of K and Br indicate that at least one plug contains late-stage evaporite minerals. Salinities approaching halite saturation were observed. Samples from holes away from diapiric structures showed little change in pore-water chemistry, except for loss of SO4 and other variations attributable to early-stage diagenetic reactions with enclosing sediments. Thus, increased salt concentrations in even shallow sediments from this part of the Gulf appear to provide an indicator of salt masses at depth. ?? 1969.

  18. Reconciling the elemental and Sr isotope composition of Himalayan weathering fluxes: insights from the carbonate geochemistry of stream waters

    NASA Astrophysics Data System (ADS)

    Jacobson, Andrew D.; Blum, Joel D.; Walter, Lynn M.

    2002-10-01

    Determining the relative proportions of silicate vs. carbonate weathering in the Himalaya is important for understanding atmospheric CO 2 consumption rates and the temporal evolution of seawater Sr. However, recent studies have shown that major element mass-balance equations attribute less CO 2 consumption to silicate weathering than methods utilizing Ca/Sr and 87Sr/ 86Sr mixing equations. To investigate this problem, we compiled literature data providing elemental and 87Sr/ 86Sr analyses for stream waters and bedrock from tributary watersheds throughout the Himalaya Mountains. In addition, carbonate system parameters (P CO 2, mineral saturation states) were evaluated for a selected suite of stream waters. The apparent discrepancy between the dominant weathering source of dissolved major elements vs. Sr can be reconciled in terms of carbonate mineral equilibria. Himalayan streams are predominantly Ca 2+-Mg 2+-HCO 3- waters derived from calcite and dolomite dissolution, and mass-balance calculations demonstrate that carbonate weathering contributes ˜87% and ˜76% of the dissolved Ca 2+ and Sr 2+, respectively. However, calculated Ca/Sr ratios for the carbonate weathering flux are much lower than values observed in carbonate bedrock, suggesting that these divalent cations do not behave conservatively during stream mixing over large temperature and P CO 2 gradients in the Himalaya. The state of calcite and dolomite saturation was evaluated across these gradients, and the data show that upon descending through the Himalaya, ˜50% of the streams evaluated become highly supersaturated with respect to calcite as waters warm and degas CO 2. Stream water Ca/Mg and Ca/Sr ratios decrease as the degree of supersaturation with respect to calcite increases, and Mg 2+, Ca 2+, and HCO 3- mass balances support interpretations of preferential Ca 2+ removal by calcite precipitation. On the basis of patterns of saturation state and P CO 2 changes, calcite precipitation was estimated

  19. Radioactivity and geochemistry of selected mineral-spring waters in the Western United States; basic data and multivariate statistical analysis

    USGS Publications Warehouse

    Felmlee, J.K.; Cadigan, R.A.

    1982-01-01

    Multivariate statistical analyses were performed on data from 156 mineral-spring sites in nine Western States to analyze relationships among the various parameters measured in the spring waters. Correlation analysis and R-mode factor analysis indicate that three major factors affect water composition in the spring systems studied: (1) duration of water circulation, (2) depth of water circulation, and (3) partial pressure of carbon dioxide. An examination of factor scores indicates that several types of hydrogeologic systems were sampled. Most of the samples are (1) older water from deeper circulating systems having relatively high salinity, high temperature, and low Eh or (2) younger water from shallower circulating systems having relatively low salinity, low temperature, and high Eh. The rest of the samples are from more complex systems. Any of the systems can have a relatively high or low content of dissolved carbonate species, resulting in a low or high pH, respectively. Uranium concentrations are commonly higher in waters of relatively low temperature and high Eh, and radium concentrations are commonly higher in waters having a relatively high carbonate content (low pH) and, secondarily, relatively high salinity. Water samples were collected and (or) measurements were taken at 156 of the 171 mineral-spring sites visited. Various samples were analyzed for radium, uranium, radon, helium, and radium-228 as well as major ions and numerous trace elements. On-site measurements for physical properties including temperature, specific conductance, pH, Eh, and dissolved oxygen were made. All constituents and properties show a wide range of values. Radium concentrations range from less than 0.01 to 300 picocuries per liter; they average 1.48 picocuries per liter and have an anomaly threshold value of 171 picocuries per liter for the samples studied. Uranium concentrations range from less than 0.01 to 120 micrograms per liter and average 0.26 micrograms per liter; they

  20. The hydro- and multi-isotope geochemistry of iron-rich ground waters emerging at the southern Baltic Sea coast line

    NASA Astrophysics Data System (ADS)

    Lipka, Marko; Wu, Zijun; Escher, Peter; Struck, Ulrich; Dellwig, Olaf; Schafmeister, Maria; Böttcher*, Michael E.

    2013-04-01

    Iron-rich groundwater springs emerging at the shore zone of the southern Baltic Sea (BS; Site Meschendorf) were examined on a seasonal base for a period of about two years. Besides major, minor, and trace elements, stable isotopes of water (H-2, O-18), dissolved inorganic carbon (DIC; C-13), and sulfate (S-34) were analyzed. The stream bed sediment was extracted for the geochemistry of the newly formed precipitates and further characterized via SEM-EDAX. Subsequently, the hydrogeochemical results were subjected to a thermodynamic analysis via the PHREEQC speciation model. The springs emerge from small pits (about 60 cm diameter; up to 15cm depth). Surrounding sediments are sandy with gravels found at depth and corresponding high permeabilities. The positions of different springs on the shore zone were stable during the investigation period while the shape of the pits and the stream beds may vary due to wind- and wave-driven forces. Selected measurements of spring yield discharges close to 10 L/min. The H-2 and O-18 contents of the spring waters indicate the ground water to originate from relatively young mixed meteoric waters. The hydrochemistry of the springs was similar and showed some variability in between which indicates that the genetic processes for the ground water before reaching the surface may slightly differ. The springs are characterized by dissolved Ca, Mg, Na, DIC and sulfate, mainly reflecting the interaction with soils and bedrocks in the recharge area that is dominated by marly till. The oxygen-free ground water is rich in Fe, P, and DIC. Iron and dissolved sulfate originate from the oxidation of pyrite, as further confirmed by the 34-S signature of sulfate. The carbon isotope signature of DIC indicates a mixture of biogenic CO2 from the soil zone with some water-rock interaction with carbonate minerals. The streams flow towards the BS and, in contact with the atmosphere, outgas carbon dioxide and takes up oxygen. Upon CO2-degassing, C-12 is

  1. Petrology and geochemistry of Late Holocene felsic magmas from Rungwe volcano (Tanzania), with implications for trachytic Rungwe Pumice eruption dynamics

    NASA Astrophysics Data System (ADS)

    Fontijn, Karen; Elburg, Marlina A.; Nikogosian, Igor K.; van Bergen, Manfred J.; Ernst, Gerald G. J.

    2013-09-01

    Rungwe in southern Tanzania is an active volcanic centre in the East African Rift System, characterised by Plinian-style explosive eruptions of metaluminous to slightly peralkaline trachytic silica-undersaturated magmas during its late Holocene history. Variations in whole-rock major and trace element compositions of erupted products have been investigated, in combination with electron microprobe data for melt inclusions and phenocrysts comprising sanidine, biotite, clinopyroxene, titanomagnetite, ilmenite, haüyne, titanite, apatite and traces of plagioclase and amphibole. Compositional variations largely reflect fractional crystallisation, with a limited influence of magma mixing. Subtle variations in whole-rock composition and mineralogical characteristics between and within deposits, suggest the existence of a chemically zoned trachytic magma chamber beneath Rungwe. For the two most important studied deposits, the Isongole and Rungwe Pumice, co-existing Fe-Ti oxides constrain pre-eruptive temperature to 915-950 °C and oxygen fugacity to NNO + 0.25-NNO + 0.45. For the Rungwe Pumice, melt inclusions suggest that the melt was water-undersaturated (maximum inferred H2O concentration 5.5 wt.%). In the range of the defined pre-eruptive temperatures, this corresponds to melt viscosities as low as 103.3 Pa · s, i.e. significantly lower than magmas that typically generate highly explosive eruptions. Because no microlites formed in the conduit during ascent, which would have strongly increased the effective magma viscosity, the highly explosive nature of the eruptions may be attributable to a crucial role of exsolved CO2 and S phases, and very high ascent rates.

  2. Trace element geochemistry and surface water chemistry of the Bon Air coal, Franklin County, Cumberland Plateau, southeast Tennessee

    USGS Publications Warehouse

    Shaver, S.A.; Hower, J.C.; Eble, C.F.; McLamb, E.D.; Kuers, K.

    2006-01-01

    surface waters, highest levels of most trace elements occur in mine-adit or mine-dump drainage. Effluent flow rates strongly affect both acidity and trace element levels. Adit drainages where flow is only a trickle have the most acidic waters (pH 3.78-4.80) and highest trace element levels (up to two orders of magnitude higher than in non-mine site waters). Nonetheless, nearly all surface waters have low absolute concentrations of trace elements of environmental concern, and all waters sampled meet U.S. EPA primary drinking water standards and aquatic life criteria for all elements analyzed. Secondary drinking water standards are also met for all parameters except Al, pH, Fe, and Mn, but even in extreme cases (mine waters with pH as low as 3.78 and up to 1243 ppb Al, 6280 ppb Fe, and 721 ppb Mn, and non-mine dam-outflow waters with up to 18,400 ppb Fe and 1540 ppb Mn) downslope attenuation is apparently rapid, as down-drainage plateau-base streams show background levels for all these parameters. ?? 2005 Elsevier B.V. All rights reserved.

  3. The geochemistry of iron and manganese in the waters and sediments of Bolstadfjord, S.W. Norway

    NASA Astrophysics Data System (ADS)

    Hamilton-Taylor, John; Price, N. Brian

    1983-07-01

    The distributions of dissolved and solid phase Fe and Mn have been variously determined in vertical profiles through the water column and sediments at three stations in Bolstadfjord, S.W. Norway. Elevated concentrations of dissolved and suspended particulate Fe and Mn are associated with restricted deep waters as a result of redox reactions and with river discharge. The basin sediments are anoxic throughout but because of the greatly restricted circulation, remobilized Fe and Mn appear to remain predominantly trapped within the fjord. Differentiation of Fe and Mn occurs to the extent that Fe sulphide precipitation is ubiquitous in the sediments whereas the entrapment of Mn, probably through Mn carbonate precipitation, is found only in the sediments of the more seaward basin (maximum Mn content of 1·5% by weight).

  4. Quantitative Applications of Deep-Sea Raman Spectroscopy: Geochemistry of 1,4- thioxane in sea water

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Hester, K. C.; Walz, P. M.; Peltzer, E. T.; Brewer, P. G.

    2008-12-01

    We have developed quantitative Raman spectroscopic techniques for the novel detection of dissolved species in sea water to determine their fundamental properties. In this example we use a field-deployable Raman system to determine the solubility of 1,4-thioxane (TO) in sea water as 0.65 to 0.63 mol/kg H2O between 4.5°C and 25.0°C (which varies greatly from an earlier report of 2.75 mol/kg H2O), and to assess the conditions under which it may form a hydrate. TO is of unusual environmental interest as a breakdown product of the chemical weapon mustard gas, and thus development of non-contact field- deployable sensing techniques is highly desirable. Raman spectroscopy has typically been considered as only a qualitative technique due to the complexity of the optical path and the substantial changes in components between different instruments. We show here that by self-referencing to the ubiquitous water peaks (the water ν2 mode from 1500 to 1800 cm-1) we can derive quantitative information with a precision of ± 4%, and provide essential new information. The long-term fate of large quantities of chemical weapons disposed of in the ocean some 50 years ago is poorly known. Part of this lacking knowledge can be attributed to the hazards associated with the direct study of these materials leaving ocean scientists vulnerable when sampling in inadequately marked sites. Mustard gas (1,1'-thiobis[2-chloroethane]) represents the largest tonnage of material disposed of until the 1972 London Convention banned such activities. Thus there is strong interest in determining the fate and lifetime of these materials, their decomposition products, and the extent of the affected zones. We have earlier shown that TO forms a hydrate with a help-gas, such as methane or hydrogen sulfide, and that the temperature, pressure and reducing conditions required for hydrate formation commonly occur at known disposal sites. In fact, a mixed TO hydrate is more stable than methane hydrate by almost

  5. Quantifying early 17th century changes in Chesapeake Bay estuarine carbon dynamics from James River, VA oyster geochemistry

    NASA Astrophysics Data System (ADS)

    Grimm, B. L.; Spero, H. J.; Harding, J. M.

    2012-12-01

    The first successful European colonization of North America occurred in 1607 following the arrival of English settlers at Jamestown, Virginia. Within a few decades, land use changes and clear-cutting farming practices dramatically altered the terrestrial landscape and removed the overlying canopy and stabilizing root network of the previously-dominant hardwood forests. The Eastern oyster, Crassostrea virginica, has inhabited the Chesapeake Bay since the end of the last deglaciation. During the start of the Jamestown Colony, an extensive drought (1606-1612) shifted James River salinity zones upriver, expanding the available oyster habitat to the vicinity of Jamestown. This allowed the colonists to collect and eat oysters from areas near the colony down to the river's entry into the bay, and later discard the shells in wells and trash pits that have recently been excavated. The oysters' calcium carbonate shells discovered in these deposits act as multi-year stationary recorders preserving the local environmental chemistry throughout their life until collection. Here we present δ13C, δ18O, and radiocarbon data from historical oyster shell hinge transects that encompass the time period between ~1609 and the early 1700s. Samples include shells from the 1609 Jamestown freshwater well and five additional sites, as well as modern shells collected in 2006. Because shell δ13C and radiocarbon (14C) reflect James River δ13CDIC, it is possible to document carbon source changes during this period of land use change. Our preliminary data suggest a decrease in ambient δ13CDIC of approximately 2‰ between just prior to 1609 conditions and the modern estuary. This is most likely due to an increase in isotopically light organic carbon loading into the river as water moves more rapidly through the terrestrial system. Radiocarbon reservoir ages will also be presented to better constrain carbon flow through the system during this period of disturbance. δ18O measurements from the

  6. Geochemistry of Mine Waste and Mill Tailings, Meadow Deposits, Streambed Sediment, and General Hydrology and Water Quality for the Frohner Meadows Area, Upper Lump Gulch, Jefferson County, Montana

    USGS Publications Warehouse

    Klein, Terry L.; Cannon, Michael R.; Fey, David L.

    2004-01-01

    Frohner Meadows, an area of low-topographic gradient subalpine ponds and wetlands in glaciated terrane near the headwaters of Lump Gulch (a tributary of Prickly Pear Creek), is located about 15 miles west of the town of Clancy, Montana, in the Helena National Forest. Mining and ore treatment of lead-zinc-silver veins in granitic rocks of the Boulder batholith over the last 120 years from two sites (Frohner mine and the Nellie Grant mine) has resulted in accumulations of mine waste and mill tailings that have been distributed downslope and downstream by anthropogenic and natural processes. This report presents the results of an investigation of the geochemistry of the wetlands, streams, and unconsolidated-sediment deposits and the hydrology, hydrogeology, and water quality of the area affected by these sources of ore-related metals. Ground water sampled from most shallow wells in the meadow system contained high concentrations of arsenic, exceeding the Montana numeric water-quality standard for human health. Transport of cadmium and zinc in ground water is indicated at one site near Nellie Grant Creek based on water-quality data from one well near the creek. Mill tailings deposited in upper Frohner Meadow contribute large arsenic loads to Frohner Meadows Creek; Nellie Grant Creek contributes large arsenic, cadmium, and zinc loads to upper Frohner Meadows. Concentrations of total-recoverable cadmium, copper, lead, and zinc in most surface-water sites downstream from the Nellie Grant mine area exceeded Montana aquatic-life standards. Nearly all samples of surface water and ground water had neutral to slightly alkaline pH values. Concentrations of arsenic, cadmium, lead, and zinc in streambed sediment in the entire meadow below the mine waste and mill tailings accumulations are highly enriched relative to regional watershed-background concentrations and exceed consensus-based, probable-effects concentrations for streambed sediment at most sites. Cadmium, copper, and

  7. Geochemistry of waters from springs, wells, and snowpack on and adjacent to Medicine Lake volcano, northern California

    USGS Publications Warehouse

    Mariner, R.H.; Lowenstern, Jacob B.

    1999-01-01

    Chemical analyses of waters from cold springs and wells of the Medicine Lake volcano and surrounding region indicate small chloride anomalies that may be due to water-rock interaction or limited mixing with high-temperature geothermal fluids. The Fall River Springs (FRS) with a combined discharge of approximately 37 m3/s, show a negative correlation between chloride (Cl) and temperature, implying that the Cl is not derived from a high-temperature geothermal fluid. The high discharge from the FRS indicates recharge over a large geographic region. Chemical and isotopic variations in the FRS show that they contain a mixture of three distinct waters. The isotopic composition of recharge on and adjacent to the volcano are estimated from the isotopic composition of snow and precipitation amounts adjusted for evapotranspiration. Enough recharge of the required isotopic composition (-100 parts per thousand ??D) is available from a combination of the Medicine Lake caldera, the Fall River basin and the Long Bell basin to support the slightly warmer components of the FRS (32 m3/s). The cold-dilute part of the FRS (approximately 5 m3/s) may recharge in the Bear Creek basin or at lower elevations in the Fall River basin.

  8. Geochemistry of the Adige River water from the Eastern Alps to the Adriatic Sea (Italy): evidences for distinct hydrological components and water-rock interactions.

    PubMed

    Natali, C; Bianchini, G; Marchina, C; Knöller, K

    2016-06-01

    The Adige River flows from the Eastern Alps to the Adriatic Sea and the understanding of its fluvial dynamics can be improved by geochemical and O-H isotopic investigation. The most negative isotopic compositions are recorded close to the source (δ(18)O between -14.1 and -13.8 ‰, δD between -100.3 and -97.0 ‰), and δD and δ(18)O values generally increase downstream through the upper part (UP, the mountainous sector), stabilizing along the lower part (LP, the alluvial plain) of the river with δ(18)O between -12.4 and -11.8 ‰, δD between -86.9 and -83.7 ‰. The isotopic variations along the stream path (δ(18)O-δD vs distance from the source) depict subparallel distributions for all the investigated periods, with less negative values recorded in winter. Total dissolved solids (TDS) concentration shows the lowest value (<100 mg/l) at the river source, jumping to 310 mg/l at the Rio Ram inflow, then decreasing down to the Isarco River confluence; from here, we observed an increase toward the river mouth, with different values in the distinct sampling periods. The lowest values (140-170 mg/l) were recorded during high discharge in spring, whereas higher TDS values (up to 250 mg/l) were recorded during winter low flow conditions. Extreme TDS values were observed in the estuarine samples (up to 450 mg/l), as result of mixing with seawater. The results allow for the identification of distinct water end-members: glacio-nival component(s) characterized by the most negative isotopic composition and extremely low TDS, a rainfall component characterized by intermediate isotopic and elemental composition and groundwater characterized by the less negative isotopic composition and comparatively higher TDS. An additional component is represented by seawater, which is recorded at the lowest reach of the river during drought periods. These contributions variously mix along the stream path in the distinct hydrological periods, and the presented data are a

  9. Geochemistry of carbonate cements in Cretaceous sandstones, southeast Benue Trough, Nigeria: Implications for geochemical evolution of formation waters

    NASA Astrophysics Data System (ADS)

    Odigi, Minapuye I.; Amajor, Levi C.

    2010-05-01

    Carbonate cements including calcite, siderite, dolomite/ankerite were formed throughout the diagenetic history of the Asu River Group, Eze-Aku Group and Campano-Maastrichtain proto-Niger Delta sequences were analyzed for their major and trace element (Fe, Mn, Mg, Ca and Sr) and isotopic compositions. The earliest, ferroan carbonate cement has the following mean major and trace element concentration: Fe - 0.11 wt.%; Mn - 0.43 wt.%; Mg - 2.16 wt.%; Sr - 1050 ppm. The late ferroan has the following mean compositions: Fe - 0.48 wt.%; Mn - 0.22 wt.%; Mg - 0.25 wt.%; Sr - 1010 ppm. Earliest Fe-calcites, formed prior to significant compaction of the sediments, are relatively enriched in Mg (up to 4.12 mol.%), and have δ 18O values between -4.45% and -6.898% PDB close to the ideal original Cretaceous marine pore waters. Late calcites are relatively Fe-calcites (up to 4.2 mol.%). The earliest ferroan calcite occurs in both the Albian Asu River Group and Eze-Aku Group while late ferroan occurs in the three lithostratigraphic units studied. These geochemical variations appear to have resulted principally to reflect changes in pore water chemistry during diagenesis. The high value of Sr in cements is most likely due to interaction between pore waters and Sr-rich clay and possibly feldspar in the three lithostratigraphic units studied. Pore water Fe 2+ concentration was probably controlled by diagenetic alterations involving Fe-bearing minerals (e.g. pyrite precipitation). The low δ 18O value of some calcite cements (-11.62‰, -12.66‰, -14.31‰ PDB) suggests that an influx of meteoric water may have occurred in the Turonian-Coniacian, although the low value could also result from an abnormal geothermal gradient associated with tectonic activity in the trough. The elemental and isotopic composition of these cements varies as a function of the time of precipitation.

  10. Geochemistry of water and gas discharges from the Mt. Amiata silicic complex and surrounding areas (central Italy)

    NASA Astrophysics Data System (ADS)

    Minissale, A.; Magro, G.; Vaselli, O.; Verrucchi, C.; Perticone, I.

    1997-12-01

    The Mt. Amiata volcano in central Italy is intimately related to the post-orogenic magmatic activity which started in Pliocene times. Major, trace elements, and isotopic composition of thermal and cold spring waters and gas manifestations indicate the occurrence of three main reservoir of the thermal and cold waters in the Mt. Amiata region. The deepest one is located in an extensive carbonate reservoir buried by thick sequences of low-permeability allochthonous and neo-autochthonous formations. Thermal spring waters discharging from this aquifer have a neutral Ca-SO 4 composition due to the presence of anhydrite layers at the base of the carbonate series and, possibly, to absorption of deep-derived H 2S with subsequent oxidation to SO 42- in a system where pH is buffered by the calcite-anhydrite pair ( Marini and Chiodini, 1994). Isotopic signature of these springs and N 2-rich composition of associated gas phases suggest a clear local meteoric origin of the feeding waters, and atmospheric O 2 may be responsible for the oxidation of H 2S. The two shallower aquifers have different chemical features. One is Ca-HCO 3 in composition and located in several sedimentary formations above the Mesozoic carbonates. The other one has a Na-Cl composition and is hosted in marine sediments filling many post-orogenic NW-SE-trending basins. Strontium, Ba, F, and Br contents have been used to group waters associated with each aquifer. Although circulating to some extent in the same carbonate reservoir, the deep geothermal fluids at Latera and Mt. Amiata and thermal springs discharging from their outcropping areas have different composition: Na-Cl and Ca-SO 4 type, respectively. Considering the high permeability of the reservoir rock, the meteoric origin of thermal springs and the two different composition of the thermal waters, self-sealed barriers must be present at the boundaries of the geothermal systems. The complex hydrology of the reservoir rocks greatly affects the

  11. Water conditions and geochemistry in northern Adriatic anoxia-prone areas and response of benthic faunas to oxygen deficiencies

    NASA Astrophysics Data System (ADS)

    Zuschin, Martin; Riedel, Bettina; Stachowitsch, Michael; Cermelj, Branko

    2010-05-01

    One predicted effect of global climate change, specifically global warming, is the increase in the temperatures and stratification of shallow coastal and estuarine systems. This, coupled with ongoing anthropogenic eutrophication, will exacerbate hypoxia and benthic mortalities, significantly damaging these critical marine ecosystems. These phenomena are particularly severe on sublitoral soft-bottoms such as the poorly sorted silty sands at the study site in the northern Adriatic Sea. We deployed a specially developed underwater chamber to artificially induce anoxia in situ. Our Experimental Anoxia Generating Unit (EAGU) is a large plexiglass chamber that combines a digital camera with oxygen/hydrogen sulphide/pH sensors along with flashes and battery packs. The unit can be deployed for up to five days to autonomously generate oxygen crises and quantify both physico-chemical parameters and benthic responses. The system is initially positioned in an "open" configuration (open-sided aluminium frame) over the benthic fauna ("control" experiment). After 24 h the EAGU is switched to its "closed" configuration (plexiglass enclosure) and repositioned over the same assemblage. In this contribution, we focus on the natural oxygen content, temperature and pH of bottom waters during summer, the course of oxygen decrease during our experiments and the onset of H2S development. Oxygen content of the bottom water, a few centimetres above the sediment-water interface, ranges from ~3.5-8 but is mostly between 4-6 ml l-1 during July to September of the study periods (2005 and 2006) and decreases to zero within ~1-3 days after initiation of our experiments. In parallel, H2S starts to develop at the onset of anoxia. Water temperatures at the bottom were stable during experiments and ranged from 18.5°C to 21.4°C, but pH decreased from 8.3 to 8.1 at the beginning to 7.9 to 7.7 at the end of the experiments. Sediment profiling indicates that the diffusive benthic boundary layer is

  12. Dynamics of Water Confined in Synthetic Saponite Clays

    SciTech Connect

    Prabhudesai, S. A.; Sharma, V. K.; Mitra, S.; Mukhopadhyay, R.; Chakrabarty, D.; Vicente, Miguel A.

    2011-07-15

    The dynamics of water in two synthetic saponite clays (treated by microwave) with different interlayer spacing has been studied using the quasielastic neutron scattering technique. A model in which the molecules undergo random jump diffusion describes the dynamics of water in both clays. The dynamics of water confined in both saponite clays considered here is found to be hindered in comparison to the bulk phase. It is found that diffusivity increases for samples having higher interlayer spacing.

  13. Appendix G: Geochemistry

    SciTech Connect

    Cantrell, Kirk J.; Serne, R. Jeffrey; Zachara, John M.; Krupka, Kenneth M.; Dresel, P. Evan; Brown, Christopher F.; Freshley, Mark D.

    2008-01-17

    This appendix discusses the geology of the Hanford Site and singe-shell tank (SST) waste management areas (WMAs). The purpose is to provide the most recent geochemical information available for the SST WMAs and the Integrated Disposal Facility. This appendix summarizes the information in the geochemistry data package for the SST WMAs.

  14. Geochemistry of urban sediments from small urban areas and potential impact on surface waters: a case study in Northern Portugal

    NASA Astrophysics Data System (ADS)

    Reis, Anabela; Oliveira, Ana Isabel; Pinto, João; Parker, Andrew

    2015-04-01

    Urban sediments are an important source of contaminants in urban catchments with impact on river ecosystems. Surface runoff from impermeable surfaces transfers sediments and associated contaminants to water bodies affecting the quality of both water and sediment compartments. This study aims to evaluate the metal contents in urban sediments (road deposited sediments) in a small sized urban area, located in a rural mountainous region with no significant industrial units, or mining activities in the vicinity, and subsequently have an insight on the potential contribution to the metal loads transported by fluvial sediments in the streams from the surrounding drainage network. The area under investigation locates in the northeast Portugal, in the Trás-os-Montes region (NE Portugal). Vila Real is a rural city, with 52781 inhabitants, and in the urban area there are dispersed parks with forest and gardens; locally and in the surroundings of the city there are agricultural terrains. The industry is concentrated, in general, in the industry park. Major pollutant activities can be considered the agriculture (pollution by sediments, metals and use of fertilizers) and urban activities such as atmospheric deposition, vehicular traffic, residential activities, soil erosion and industrial activities. According to the aim of the study, road deposited sediment samples were collected in urban and periurban areas as well as in public playgrounds and in the industrial area. The samples were decomposed with aqua regia, and the concentrations of As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Zn and V were obtained by ICP-AES. The total concentrations of As, Cr, Cu, Fe, Mn, Ni, Pb, Zn and V, in road-deposited sediments, indicate relative enrichments in samples collected in the main streets and roads, showing spatial variability. The association of Cu, Pb and Zn is observed in samples collected in the streets with high traffic density and industrial activity; in general, higher relative contents

  15. Water dynamics clue to key residues in protein folding

    SciTech Connect

    Gao, Meng; Zhu, Huaiqiu; Yao, Xin-Qiu; Department of Biophysics, Kyoto University, Sakyo Kyoto 606-8502 ; She, Zhen-Su

    2010-01-29

    A computational method independent of experimental protein structure information is proposed to recognize key residues in protein folding, from the study of hydration water dynamics. Based on all-atom molecular dynamics simulation, two key residues are recognized with distinct water dynamical behavior in a folding process of the Trp-cage protein. The identified key residues are shown to play an essential role in both 3D structure and hydrophobic-induced collapse. With observations on hydration water dynamics around key residues, a dynamical pathway of folding can be interpreted.

  16. Relation of specific conductance in ground water to intersection of flow paths by wells, and associated major ion and nitrate geochemistry, Barton Springs Segment of the Edwards Aquifer, Austin, Texas, 1978-2003

    USGS Publications Warehouse

    Garner, Bradley D.; Mahler, Barbara J.

    2007-01-01

    Understanding of karst flow systems can be complicated by the presence of solution-enlarged conduits, which can transmit large volumes of water through the aquifer rapidly. If the geochemistry at a well can be related to streamflow or spring discharge (springflow), or both, the relations can indicate the presence of recent recharge in water at the well, which in turn might indicate that the well intersects a conduit (and thus a major flow path). Increasing knowledge of the occurrence and distribution of conduits in the aquifer can contribute to better understanding of aquifer framework and function. To that end, 26 wells in the Barton Springs segment of the Edwards aquifer, Austin, Texas, were investigated for potential intersection with conduits; 26 years of arbitrarily timed specific conductance measurements in the wells were compared to streamflow in five creeks that provide recharge to the aquifer and were compared to aquifer flow conditions as indicated by Barton Springs discharge. A nonparametric statistical test (Spearman's rho) was used to divide the 26 wells into four groups on the basis of correlation of specific conductance of well water to streamflow or spring discharge, or both. Potential relations between conduit intersection by wells and ground-water geochemistry were investigated through analysis of historical major ion and nitrate geochemistry for wells in each of the four groups. Specific conductance at nine wells was negatively correlated with both streamflow and spring discharge, or streamflow only. These correlations were interpreted as evidence of an influx of surface-water recharge during periods of high streamflow and the influence at the wells of water from a large, upgradient part of the aquifer; and further interpreted as indicating that four wells intersect major aquifer flow paths and five wells intersect minor aquifer flow paths (short, tributary conduits). Specific conductance at six wells was positively correlated with spring

  17. Relation of Specific Conductance in Ground Water to Intersection of Flow Paths by Wells, and Associated Major Ion and Nitrate Geochemistry, Barton Springs Segment of the Edwards Aquifer, Austin, Texas, 1978-2003

    USGS Publications Warehouse

    Garner, Bradley D.; Mahler, Barbara J.

    2007-01-01

    Understanding of karst flow systems can be complicated by the presence of solution-enlarged conduits, which can transmit large volumes of water through the aquifer rapidly. If the geochemistry at a well can be related to streamflow or spring discharge (springflow), or both, the relations can indicate the presence of recent recharge in water at the well, which in turn might indicate that the well intersects a conduit (and thus a major flow path). Increasing knowledge of the occurrence and distribution of conduits in the aquifer can contribute to better understanding of aquifer framework and function. To that end, 26 wells in the Barton Springs segment of the Edwards aquifer, Austin, Texas, were investigated for potential intersection with conduits; 26 years of arbitrarily timed specific conductance measurements in the wells were compared to streamflow in five creeks that provide recharge to the aquifer and were compared to aquifer flow conditions as indicated by Barton Springs discharge. A nonparametric statistical test (Spearman's rho) was used to divide the 26 wells into four groups on the basis of correlation of specific conductance of well water to streamflow or spring discharge, or both. Potential relations between conduit intersection by wells and ground-water geochemistry were investigated through analysis of historical major ion and nitrate geochemistry for wells in each of the four groups. Specific conductance at nine wells was negatively correlated with both streamflow and spring discharge, or streamflow only. These correlations were interpreted as evidence of an influx of surface-water recharge during periods of high streamflow and the influence at the wells of water from a large, upgradient part of the aquifer; and further interpreted as indicating that four wells intersect major aquifer flow paths and five wells intersect minor aquifer flow paths (short, tributary conduits). Specific conductance at six wells was positively correlated with spring

  18. Internal features, mineralogy and geochemistry of ferromanganese nodules from the Gulf of Cadiz: The role of the Mediterranean Outflow Water undercurrent

    NASA Astrophysics Data System (ADS)

    González, F. J.; Somoza, L.; Lunar, R.; Martínez-Frías, J.; Rubí, J. A. Martín; Torres, T.; Ortiz, J. E.; Díaz-del-Río, V.

    2010-03-01

    A large suite of Fe-Mn nodules (561 samples) were recovered during the Anastasya2001 cruise (TASYO project) along the continental margin of the Gulf of Cadiz (Eastern Central Atlantic), at the confluence of the Mediterranean Sea with the Atlantic Ocean, where extensive nodule fields were discovered. Based on wide previous studies that included swath bathymetry, multi-channel and very high-resolution seismic reflection, gravimetry, magnetism, heat flow probes and underwater photography surveys, nodules were collected at water depths ranging from 850 to 1000 m, associated with hydrocarbon-derived Mg-calcite, ankerite and dolomite chimneys and crusts. Forty-six selected samples among the various morphological types were used for the laboratory analysis of physical properties (morphology, color, surface texture, sphericity, weight and size), mineralogy (XRD, optical and electronic microscopy), geochemistry (XRF, AAS, ICP-MS, ICP-AES, EPMA, and GC-MS) and stable isotopes. The nodules show a wide range of sizes, densities, weights and morphologies. They are formed by multiple millimeter-thick layers of Fe and Mn oxyhydroxides surrounding the nucleus composed of Early-Middle Miocene plastic marl and sediment, which were derived from underlying units by fluid venting. Massive, laminated, detrital and mottled to dendritic textural features were developed by the Fe and Mn oxyhydroxide layers. The main components are Goethite, lepidocrocite, Mn oxides (7 Å manganates and 10 Å manganates), quartz, and phyllosilicates. Accessory minerals are calcite, dolomite, siderite, rhodochrosite, kutnahorite, pyrite, chalcopyrite, potassium feldspar, zircon, rutile, ilmenite and chlorite. Fe-Mn carbonates from the siderite-rhodochrosite continuous series are the principal constituent of the nuclei. Framboidal, filamentous and globular textures are observed in Fe-Mn oxides and pyrite, suggesting biogenic origin. The nodules show a high mean abundance of Fe (38.6%), moderate Mn (6.0%) and

  19. Questa baseline and pre-mining ground-water quality investigation. 14. Interpretation of ground-water geochemistry in catchments other than the Straight Creek catchment, Red River Valley, Taos County, New Mexico, 2002-2003

    USGS Publications Warehouse

    Nordstrom, D. Kirk; McCleskey, R. Blaine; Hunt, Andrew G.; Naus, Cheryl A.

    2005-01-01

    The U.S. Geological Survey, in cooperation with the New Mexico Environment Department, is investigating the pre-mining ground-water chemistry at the Molycorp molybdenum mine in the Red River Valley, New Mexico. The primary approach is to determine the processes controlling ground-water chemistry at an unmined, off-site but proximal analog. The Straight Creek catchment, chosen for this purpose, consists of the same Tertiary-age quartz-sericite-pyrite altered andesite and rhyolitic volcanics as the mine site. Straight Creek is about 5 kilometers east of the eastern boundary of the mine site. Both Straight Creek and the mine site are at approximately the same altitude, face south, and have the same climatic conditions. Thirteen wells in the proximal analog drainage catchment were sampled for ground-water chemistry. Eleven wells were installed for this study and two existing wells at the Advanced Waste-Water Treatment (AWWT) facility were included in this study. Eight wells were sampled outside the Straight Creek catchment: one each in the Hansen, Hottentot, and La Bobita debris fans, four in a well cluster in upper Capulin Canyon (three in alluvial deposits and one in bedrock), and an existing well at the U.S. Forest Service Questa Ranger Station in Red River alluvial deposits. Two surface waters from the Hansen Creek catchment and two from the Hottentot drainage catchment also were sampled for comparison to ground-water compositions. In this report, these samples are evaluated to determine if the geochemical interpretations from the Straight Creek ground-water geochemistry could be extended to other ground waters in the Red River Valley , including the mine site. Total-recoverable major cations and trace metals and dissolved major cations, selected trace metals, anions, alkalinity; and iron-redox species were determined for all surface- and ground-water samples. Rare-earth elements and low-level As, Bi, Mo, Rb, Re, Sb, Se, Te, Th, U, Tl, V, W, Y, and Zr were

  20. Dynamics and mechanism of ultrafast water-protein interactions.

    PubMed

    Qin, Yangzhong; Wang, Lijuan; Zhong, Dongping

    2016-07-26

    Protein hydration is essential to its structure, dynamics, and function, but water-protein interactions have not been directly observed in real time at physiological temperature to our awareness. By using a tryptophan scan with femtosecond spectroscopy, we simultaneously measured the hydration water dynamics and protein side-chain motions with temperature dependence. We observed the heterogeneous hydration dynamics around the global protein surface with two types of coupled motions, collective water/side-chain reorientation in a few picoseconds and cooperative water/side-chain restructuring in tens of picoseconds. The ultrafast dynamics in hundreds of femtoseconds is from the outer-layer, bulk-type mobile water molecules in the hydration shell. We also found that the hydration water dynamics are always faster than protein side-chain relaxations but with the same energy barriers, indicating hydration shell fluctuations driving protein side-chain motions on the picosecond time scales and thus elucidating their ultimate relationship. PMID:27339138

  1. Dynamics of water confined in lyotropic liquid crystals: Molecular dynamics simulations of the dynamic structure factor

    NASA Astrophysics Data System (ADS)

    Mantha, Sriteja; Yethiraj, Arun

    2016-02-01

    The properties of water under confinement are of practical and fundamental interest. In this work, we study the properties of water in the self-assembled lyotropic phases of Gemini surfactants with a focus on testing the standard analysis of quasi-elastic neutron scattering (QENS) experiments. In QENS experiments, the dynamic structure factor is measured and fit to models to extract the translational diffusion constant, DT, and rotational relaxation time, τR. We test this procedure by using simulation results for the dynamic structure factor, extracting the dynamic parameters from the fit as is typically done in experiments, and comparing the values to those directly measured in the simulations. We find that the de-coupling approximation, where the intermediate scattering function is assumed to be a product of translational and rotational contributions, is quite accurate. The jump-diffusion and isotropic rotation models, however, are not accurate when the degree of confinement is high. In particular, the exponential approximations for the intermediate scattering function fail for highly confined water and the values of DT and τR can differ from the measured value by as much as a factor of two. Other models have more fit parameters, however, and with the range of energies and wave-vectors accessible to QENS, the typical analysis appears to be the best choice. In the most confined lamellar phase, the dynamics are sufficiently slow that QENS does not access a large enough time scale.

  2. Molecular dynamics studies of interfacial water at the alumina surface.

    SciTech Connect

    Argyris, Dr. Dimitrios; Ho, Thomas; Cole, David

    2011-01-01

    Interfacial water properties at the alumina surface were investigated via all-atom equilibrium molecular dynamics simulations at ambient temperature. Al-terminated and OH-terminated alumina surfaces were considered to assess the structural and dynamic behavior of the first few hydration layers in contact with the substrates. Density profiles suggest water layering up to {approx}10 {angstrom} from the solid substrate. Planar density distribution data indicate that water molecules in the first interfacial layer are organized in well-defined patterns dictated by the atomic terminations of the alumina surface. Interfacial water exhibits preferential orientation and delayed dynamics compared to bulk water. Water exhibits bulk-like behavior at distances greater than {approx}10 {angstrom} from the substrate. The formation of an extended hydrogen bond network within the first few hydration layers illustrates the significance of water?water interactions on the structural properties at the interface.

  3. STABLE ISOTOPES AS INDICATORS OF SOIL WATER DYNAMICS IN WATERSHEDS

    EPA Science Inventory

    Stream water quality and quantity depend on discharge rates of water and nutrients from soils. However, soil-water storage is very dynamic and strongly influenced by plants. We analyzed stable isotopes of oxygen and hydrogen to quantify spatial and temporal changes in evaporati...

  4. Method of analysis and quality-assurance practices by the U.S. Geological Survey Organic Geochemistry Research Group; determination of geosmin and methylisoborneol in water using solid-phase microextraction and gas chromatography/mass spectrometry

    USGS Publications Warehouse

    Zimmerman, L.R.; Ziegler, A.C.; Thurman, E.M.

    2002-01-01

    A method for the determination of two common odor-causing compounds in water, geosmin and 2-methylisoborneol, was modified and verified by the U.S. Geological Survey's Organic Geochemistry Research Group in Lawrence, Kansas. The optimized method involves the extraction of odor-causing compounds from filtered water samples using a divinylbenzene-carboxen-polydimethylsiloxane cross-link coated solid-phase microextraction (SPME) fiber. Detection of the compounds is accomplished using capillary-column gas chromatography/mass spectrometry (GC/MS). Precision and accuracy were demonstrated using reagent-water, surface-water, and ground-water samples. The mean accuracies as percentages of the true compound concentrations from water samples spiked at 10 and 35 nanograms per liter ranged from 60 to 123 percent for geosmin and from 90 to 96 percent for 2-methylisoborneol. Method detection limits were 1.9 nanograms per liter for geosmin and 2.0 nanograms per liter for 2-methylisoborneol in 45-milliliter samples. Typically, concentrations of 30 and 10 nanograms per liter of geosmin and 2-methylisoborneol, respectively, can be detected by the general public. The calibration range for the method is equivalent to concentrations from 5 to 100 nanograms per liter without dilution. The method is valuable for acquiring information about the production and fate of these odor-causing compounds in water.

  5. Water dynamics for North Carolina v. Vinifera

    Technology Transfer Automated Retrieval System (TEKTRAN)

    As North Carolina wine grape (V. vinifera) production intensifies, the importance of water management must be addressed. Grape yield and composition, and consequently wine quality, are profoundly influenced by the water regime under which the grapes were produced. Despite the importance of water man...

  6. Quantification of Dynamic Water-Rock-Microbe Interactions in a Travertine-Depositing Hot Spring, Mammoth Hot Springs, Yellowstone National Park, USA

    NASA Astrophysics Data System (ADS)

    DeMott, L. M.; Sivaguru, M.; Fried, G.; Sanford, R. A.; Fouke, B. W.

    2014-12-01

    Filamentous microbial mats in a travertine-depositing hot spring at Mammoth Hot Springs in Yellowstone National Park exert primary controls on the growth rate, mineralogy, and crystal fabric of calcium carbonate minerals (travertine) that precipitate in the spring. Filaments directly affect porosity and permeability of travertine by providing a structural framework consisting of "ropes" of microbial cells around which carbonate minerals precipitate, creating a uniquely biogenetic mineral fabric characterized by horizontal layers of large tubular pores. Nanometer scale microscopy reveals that these mineral fabrics may be directly tied to microbial activities, as aragonite crystals precipitating directly on filaments are smaller and more densely packed than crystals precipitating on extra-polymeric substances (EPS) between filaments. In order to more closely examine the processes which control calcium carbonate crystallization dynamics in this system, a high-resolution transect of water and travertine was sampled for geochemistry, microscopy, and microbial biomass along the primary flow path from upstream to downstream of Narrow Gauge spring at Mammoth Hot Springs. Travertine samples were analyzed for petrography using transmitted light, cathodoluminescence, and laser confocal microscopy to examine crystal morphology and associations with microbial filaments and provide insight on pore network distributions. Additionally, travertine and spring water geochemistry was also analyzed for major and trace ions, δ34S, δ13C, and δ18O, to identify any trends that may relate to crystallization rates, microbial biomass, or crystal habit. Total biomass was determined using dried weight. Water-rock-microbe interactions result in upstream-to-downstream variations in travertine crystal morphology and water chemistry that are directly related to systematic changes in microbial biomass and community respiration. Geochemical modeling lends insight into the biogeochemical reactions

  7. Global water dynamics: issues for the 21st century.

    PubMed

    Simonovic, Slobodan P

    2002-01-01

    The WorldWater system dynamics model has been developed for modeling the global world water balance and capturing the dynamic character of the main variables affecting water availability and use in the future. Despite not being a novel approach, system dynamics offers a new way of addressing complex systems. WorldWater simulations are clearly demonstrating the strong feedback relation between water availability and different aspects of world development. Results of numerous simulations are contradictory to the assumption made by many global modelers that water is not an issue on the global scale. Two major observations can be made from early simulations: (a) the use of clean water for dilution and transport of wastewater, if not dealt with in other ways, imposes a major stress on the global world water balance; and (b) water use by different sectors is demonstrating quite different dynamics than predicted by classical forecasting tools and other water-models. Inherent linkages between water quantity and quality sectors with food, industry, persistent pollution, technology, and non-renewable resources sectors of the model create shoot and collapse behavior in water use dynamics. This paper discusses a number of different water-related scenarios and their implications on the global water balance. In particular, two extreme scenarios (business as usual - named "Chaos", and unlimited desalination - named "Ocean") are presented in the paper. Based on the conclusions derived from these two extreme cases a set of more moderate and realistic scenarios (named "Conservation") is proposed and their consequences on the global water balance are evaluated. PMID:12019833

  8. Linking Weathering, Rock Moisture Dynamics, Geochemistry, Runoff, Vegetation and Atmospheric Processes through the Critical Zone: Graduate Student led Research at the Eel River Critical Zone Observatory

    NASA Astrophysics Data System (ADS)

    Dietrich, W. E.

    2014-12-01

    In the Eel River Critical Zone Observatory lies Rivendell, a heavily-instrumented steep forested hillslope underlain by nearly vertically dipping argillite interbedded with sandstone. Under this convex hillslope lies "Zb", the transition to fresh bedrock, which varies from less than 6 m below the surface near the channel to 20 m at the divide. Rempe and Dietrich (2014, PNAS) show that the Zb profile can be predicted from the assumption that weathering occurs when drainage is induced in the uplifting fresh bedrock under hillslopes by lateral head gradients driven by channel incision at the hillslope boundary. Infiltrating winter precipitation is impeded at the lower conductivity boundary at Zb, generating perched groundwater that dynamically pulses water laterally to the channel, controlling stream runoff. Below the soil and above the water table lies an unsaturated zone through which all recharge to the perched groundwater (and thus all runoff to channels) occurs. It is this zone and the waters in them that profoundly affect critical zone processes. In our seasonally dry environment, the first rains penetrate past the soil and moisten the underlying weathered bedrock (Salve et al., 2012, WRR). It takes about 200 to 400 mm of cumulative rain, however, before the underlying groundwater rises significantly. Oshun et al (in review) show that by this cumulative rainfall the average of the wide-ranging isotopic signature of rain reaches a nearly constant average annual value. Consequently, the recharging perched groundwater shows only minor temporal isotopic variation. Kim et al, (2014, GCA) find that the winter high-flow groundwater chemistry is controlled by relatively fast-reacting cation exchange processes, likely occurring in transit in the unsaturated zone. Oshun also demonstrates that the Douglas fir rely on this rock moisture as a water source, while the broadleaf trees (oaks and madrone) use mostly soil moisture. Link et al (2014 WRR) show that Doug fir declines

  9. Dynamic behavior of interfacila water at the silica surface

    SciTech Connect

    Argyris, Dr. Dimitrios; Cole, David R; Striolo, Alberto

    2009-01-01

    Molecular dynamics simulations were employed to study the dynamics properties of water at the silica-liquid interface at ambient temperature. Three different degrees of hydroxylation of a crystalline silica surface were used. To assess the water dynamic properties we calculated the residence probability and in-plane mean square displacement as a function of distance from the surface. The data indicate that water molecules at the fully hydroxylated surface remain longer, on average, in the interfacial region than in the other cases. By assessing the dynamics of molecular dipole moment and hydrogen-hydrogen vector an anisotropic reorientation was discovered for interfacial water in contact with any of the surfaces considered. However, the features of the anisotropic reorientation observed for water molecules depend strongly on the relative orientation of interfacial water molecules and their interactions with surface hydroxyl groups. On the partially hydroxylated surface, where water molecules with hydrogen-down and hydrogen-up orientation are both found, those water molecules associated with surface hydroxyl groups remain at the adsorbed locations longer and reorient slower than the other water molecules. A number of equilibrium properties, including density profiles, hydrogen bond networks, charge densities, and dipole moment densities are also reported to explain the dynamics results.

  10. Dynamics of water clusters in solution with LiCl

    NASA Astrophysics Data System (ADS)

    Corsaro, Carmelo; Mallamace, Domenico; Cicero, Nicola; Vasi, Sebastiano; Dugo, Giacomo; Mallamace, Francesco

    2016-01-01

    In this work we study by means of Nuclear Magnetic Resonance spectroscopy the dynamics of the different water clusters that form within a solution with LiCl at eutectic concentration in the temperature range 320-205 K. This solution is considered a model system allowing the investigation of water properties in the deep supercooled regime in its bulk phase. Our data reveal two important dynamical changes occurring at two relevant temperatures for water: the highest temperature coincides with that of the water density maximum (277 K) and the lowest with that of the so-called dynamical crossover (≃ 225 K). We interpret our data in terms of the different influence that the ions exert on water by lowering the temperature and of the tendency that water displays to develop its characteristic hydrogen bond network.

  11. Dynamics of the cytoskeleton: How much does water matter?

    NASA Astrophysics Data System (ADS)

    Lenormand, Guillaume; Millet, Emil; Park, Chan Young; Hardin, C. Corey; Butler, James P.; Moldovan, Nicanor I.; Fredberg, Jeffrey J.

    2011-06-01

    The principal constituent of the living cell is water. The role of the hydration shell and bulk H2O solvent is well recognized in the dynamics of isolated proteins, but the role of water in the dynamics of the integrated living cytoskeleton (CSK) remains obscure. Here we report a direct connection of dynamics of water to dynamics of the integrated CSK. The latter are known to be scale-free and to hinge upon a frequency f0 that is roughly invariant across cell types. Although f0 is comparable in magnitude to the rotational relaxation frequency of water (gigahertz range), the physical basis of f0 remains unknown. Using the human airway smooth muscle cell as a model system, we show here that replacing water acutely with deuterium oxide impacts CSK dynamics in major ways, slowing CSK remodeling dynamics appreciably, and lowering f0 by up to four orders of magnitude. Although these observations do not distinguish contributions of bulk solvent versus hydration shell, they suggest a unifying hypothesis, namely, that dynamics of integrated CSK networks are slaved in a direct fashion to fluctuations arising in intracellular water.

  12. Hydrological dynamics of water sources in a Mediterranean lagoon

    NASA Astrophysics Data System (ADS)

    Stumpp, C.; Ekdal, A.; Gönenc, I. E.; Maloszewski, P.

    2014-07-01

    Lagoons are important ecosystems occupying large coastal areas worldwide. Lagoons contain various mixtures of marine and freshwater sources which are highly dynamic in time. However, it often remains a challenge to identify and quantify dynamic changes of water sources, particularly in heterogeneous lagoon systems like the Köycegiz-Dalyan Lagoon (KDL), which is located at the southwest of Turkey on the Mediterranean Sea coast. The objective of this study was to quantify different contributions of potential water sources i.e. surface water, groundwater and seawater in the lagoon and how these water sources changed over time and space. In the wet and dry season stable isotopes of water, chloride concentration (Cl-) and salinity were measured in two depths in the lagoon and surrounding water bodies (sea, lake, groundwater). Different components of water sources were quantified with a three component endmember mixing analysis. Differences in Cl- and stable isotopes over time indicated the dynamic behaviour of the system. Generally, none of the groundwater samples was impacted by water of the Mediterranean Sea. During the wet season, most of the lagoon water (>95%) was influenced by freshwater and vertically well mixed. During the dry season, high Cl- in the deeper sampling locations indicated a high contribution of marine water throughout the entire lagoon system due to salt water intrusion. However, a distinct layering in the lagoon was obvious from low Cl- and depleted isotope contents close to the surface supporting freshwater inflow into the system even during the dry season. Besides temporal dynamics also spatial heterogeneities were identified. Changes in water sources were most evident in the main lagoon channel compared to more isolate lagoon lakes, which were influenced by marine water even in the wet season, and compared to side branches indicating slower turnover times. We found that environmental tracers helped to quantify contributions of different water

  13. Water dynamics under changing land cover

    NASA Astrophysics Data System (ADS)

    Vaze, J.; Zhang, Y. Q.; Zhang, L.

    2015-06-01

    Most of the forested headwater catchments are an important source of water supply in many parts of the world. A prime example is southeast Australia where forests supply major river systems and towns and cities with water. It is critical for an informed and adaptive water resource management to understand changes in streamflow caused by vegetation changes in these headwater forest catchments. Natural disturbances such as bushfires and anthropogenic activities like forestation, deforestation, or logging alter vegetation, evapotranspiration and soil water status, and may affect water supplies. Although catchment water yield is mainly controlled by climatic conditions, but it is also strongly influenced by land cover changes because of natural disturbances and anthropogenic activities. It is necessary to accurately estimate streamflow in water supply catchments subjected to dramatic land surface changes. This paper summarises the methods commonly used to investigate the impacts of land cover change on water resources, and provides some examples of impacts of afforestation/deforestation and bushfire on water resources in two southeast Australian catchments.

  14. Geochemistry and water quality assessment of central Main Ethiopian Rift natural waters with emphasis on source and occurrence of fluoride and arsenic

    NASA Astrophysics Data System (ADS)

    Rango, Tewodros; Bianchini, Gianluca; Beccaluva, Luigi; Tassinari, Renzo

    2010-07-01

    Drinking water supply for the Main Ethiopian Rift (MER) area principally relies on groundwater wells and springs and is characterized by natural source of elevated fluoride concentration. New analyses reveal that the F - geochemical anomaly is associated with other potentially toxic elements such as As, U, Mo and B. Particularly, 35% of the 23 investigated groundwater wells and 70% of the 14 hot springs (and geothermal wells) show arsenic concentrations above the recommended limit of 10 μg/L ( WHO, 2006). Arsenic in groundwater wells has a positive correlation with Na + ( R2 = 0.63) and alkalinity ( HCO3-; R2 = 0.70) as well as with trace elements such as U ( R2 = 0.70), Mo ( R2 = 0.79) and V ( R2 = 0.68). PHREEQC speciation modelling indicates that Fe oxides and hydroxides are stable in water systems, suggesting their role as potential adsorbents that could influence the mobility of arsenic. Chemical analyses of leachates from MER rhyolitic rocks and their weathered and re-worked fluvio-lacustrine sediments were performed to evaluate their contribution as a source of the mentioned geochemical anomalies. These leachates were obtained from a 1-year leaching experiment on powdered rocks and sediments mixed with distilled water (10 g:50 ml). They contain as much as 220 μg/L of As, 7.6 mg/L of F -, 181 μg/L of Mo, 64 μg/L of U and 254 μg/L of V suggesting that the local sediments represent the main source and reservoir of toxic elements. These elements, originally present in the glassy portion of the MER rhyolitic rocks were progressively concentrated in weathered and re-deposited products. Therefore, together with the renowned F - problem, the possible presence of further geochemical anomalies have to be considered in water quality issues and future work has to investigate their possible health impact on the population of MER and other sectors of the East African Rift.

  15. Hydrological dynamics of water sources in a Mediterranean lagoon

    NASA Astrophysics Data System (ADS)

    Stumpp, C.; Ekdal, A.; Gönenc, I. E.; Maloszewski, P.

    2014-12-01

    Lagoons are important ecosystems occupying large coastal areas worldwide. Lagoons contain various mixtures of marine and freshwater sources which are highly dynamic in time. However, it often remains a challenge to identify and quantify dynamic changes of water sources, particularly in heterogeneous lagoon systems like the Köycegiz-Dalyan lagoon (KDL), which is located at the south-west of Turkey on the Mediterranean Sea coast. The objective of this study was to quantify different contributions of potential water sources i.e. surface water, groundwater and seawater in the lagoon and how these water sources changed over time and space. In the wet- and dry-season stable isotopes of water, chloride concentration (Cl-) and salinity were measured in two depths in the lagoon and surrounding water bodies (sea, lake, groundwater). Different components of water sources were quantified with a three component endmember mixing analysis. Differences in Cl- and stable isotopes over time indicated the dynamic behaviour of the system. Generally, none of the groundwater samples was impacted by water of the Mediterranean Sea. During the wet season, most of the lagoon water (> 95%) was influenced by freshwater and vertically well mixed. During the dry season, high Cl- in the deeper sampling locations indicated a high contribution of marine water throughout the entire lagoon system due to saltwater intrusion. However, a distinct layering in the lagoon was obvious from low Cl- and depleted isotope contents close to the surface supporting freshwater inflow into the system even during the dry season. Besides temporal dynamics also spatial heterogeneities were identified. Changes in water sources were most evident in the main lagoon channel compared to more isolate lagoon lakes, which were influenced by marine water even in the wet season, and compared to side branches indicating slower turnover times. We found that environmental tracers helped to quantify highly dynamic and

  16. Sulfur geochemistry of hydrothermal waters in Yellowstone National Park, Wyoming, USA. III. An anion-exchange resin technique for sampling and preservation of sulfoxyanions in natural waters

    PubMed Central

    Druschel, Greg K; Schoonen, Martin AA; Nordstrom, D Kirk; Ball, James W; Xu, Yong; Cohn, Corey A

    2003-01-01

    A sampling protocol for the retention, extraction, and analysis of sulfoxyanions in hydrothermal waters has been developed in the laboratory and tested at Yellowstone National Park and Green Lake, NY. Initial laboratory testing of the anion-exchange resin Bio-Rad™ AG1-X8 indicated that the resin was well suited for the sampling, preservation, and extraction of sulfate and thiosulfate. Synthetic solutions containing sulfate and thiosulfate were passed through AG1-X8 resin columns and eluted with 1 and 3 M KCl, respectively. Recovery ranged from 89 to 100%. Comparison of results for water samples collected from five pools in Yellowstone National Park between on-site 1C analysis (U.S. Geological Survey mobile lab) and IC analysis of resin-stored sample at SUNY-Stony Brook indicates 96 to 100% agreement for three pools (Cinder, Cistern, and an unnamed pool near Cistern) and 76 and 63% agreement for two pools (Sulfur Dust and Frying Pan). Attempts to extract polythionates from the AG1-X8 resin were made using HCl solutions, but were unsuccessful. Bio-Rad™ AG2-X8, an anion-exchange resin with weaker binding sites than the AG1-X8 resin, is better suited for polythionate extraction. Sulfate and thiosulfate extraction with this resin has been accomplished with KCl solutions of 0.1 and 0.5 M, respectively. Trithionate and tetrathionate can be extracted with 4 M KCl. Higher polythionates can be extracted with 9 M hydrochloric acid. Polythionate concentrations can then be determined directly using ion chromatographic methods, and laboratory results indicate recovery of up to 90% for synthetic polythionate solutions using AG2-X8 resin columns.

  17. Evaluating Water Conservation and Reuse Policies Using a Dynamic Water Balance Model

    NASA Astrophysics Data System (ADS)

    Qaiser, Kamal; Ahmad, Sajjad; Johnson, Walter; Batista, Jacimaria R.

    2013-02-01

    A dynamic water balance model is created to examine the effects of different water conservation policies and recycled water use on water demand and supply in a region faced with water shortages and significant population growth, the Las Vegas Valley (LVV). The model, developed using system dynamics approach, includes an unusual component of the water system, return flow credits, where credits are accrued for returning treated wastewater to the water supply source. In LVV, Lake Mead serves as, both the drinking water source and the receiving body for treated wastewater. LVV has a consumptive use allocation from Lake Mead but return flow credits allow the water agency to pull out additional water equal to the amount returned as treated wastewater. This backdrop results in a scenario in which conservation may cause a decline in the available water supply. Current water use in LVV is 945 lpcd (250 gpcd), which the water agency aims to reduce to 752 lpcd (199 gpcd) by 2035, mainly through water conservation. Different conservation policies focused on indoor and outdoor water use, along with different population growth scenarios, are modeled for their effects on the water demand and supply. Major contribution of this study is in highlighting the importance of outdoor water conservation and the effectiveness of reducing population growth rate in addressing the future water shortages. The water agency target to decrease consumption, if met completely through outdoor conservation, coupled with lower population growth rate, can potentially satisfy the Valley's water demands through 2035.

  18. Evaporation dynamics of femtoliter water capillary bridges

    NASA Astrophysics Data System (ADS)

    Cho, Kun; Hwang, In Gyu; Kim, Yeseul; Lim, Su Jin; Lim, Jun; Kim, Joon Heon; Gim, Bopil; Kim, Jung Gu; Weon, Byung Mook

    2015-11-01

    Capillary bridges are usually formed by a small liquid volume in confined space between two solid surfaces and particularly they have lower internal pressure than 1 atm at femtoliter scales. Femtoliter capillary bridges exhibit rapid evaporation rates. To quantify detailed evaporation kinetics of femtoliter bridges, we present a feasible protocol to directly visualize femtoliter water bridges that evaporate in still air between a microsphere and a flat substrate by utilizing transmission X-ray microscopy. Precise measurements of evaporation kinetics for water bridges indicate that lower water pressure than 1 atm can significantly decelerate evaporation by suppression of vapor diffusion. This finding would provide a consensus to understand evaporation of ultrasmall capillary bridges.

  19. Water Determines the Structure and Dynamics of Proteins.

    PubMed

    Bellissent-Funel, Marie-Claire; Hassanali, Ali; Havenith, Martina; Henchman, Richard; Pohl, Peter; Sterpone, Fabio; van der Spoel, David; Xu, Yao; Garcia, Angel E

    2016-07-13

    Water is an essential participant in the stability, structure, dynamics, and function of proteins and other biomolecules. Thermodynamically, changes in the aqueous environment affect the stability of biomolecules. Structurally, water participates chemically in the catalytic function of proteins and nucleic acids and physically in the collapse of the protein chain during folding through hydrophobic collapse and mediates binding through the hydrogen bond in complex formation. Water is a partner that slaves the dynamics of proteins, and water interaction with proteins affect their dynamics. Here we provide a review of the experimental and computational advances over the past decade in understanding the role of water in the dynamics, structure, and function of proteins. We focus on the combination of X-ray and neutron crystallography, NMR, terahertz spectroscopy, mass spectroscopy, thermodynamics, and computer simulations to reveal how water assist proteins in their function. The recent advances in computer simulations and the enhanced sensitivity of experimental tools promise major advances in the understanding of protein dynamics, and water surely will be a protagonist. PMID:27186992

  20. Hydration-dependent dynamic crossover phenomenon in protein hydration water

    NASA Astrophysics Data System (ADS)

    Wang, Zhe; Fratini, Emiliano; Li, Mingda; Le, Peisi; Mamontov, Eugene; Baglioni, Piero; Chen, Sow-Hsin

    2014-10-01

    The characteristic relaxation time τ of protein hydration water exhibits a strong hydration level h dependence. The dynamic crossover is observed when h is higher than the monolayer hydration level hc=0.2-0.25 and becomes more visible as h increases. When h is lower than hc, τ only exhibits Arrhenius behavior in the measured temperature range. The activation energy of the Arrhenius behavior is insensitive to h, indicating a local-like motion. Moreover, the h dependence of the crossover temperature shows that the protein dynamic transition is not directly or solely induced by the dynamic crossover in the hydration water.

  1. Ecohydrology of dry regions: storage versus pulse soil water dynamics

    USGS Publications Warehouse

    Lauenroth, William K.; Schlaepfer, Daniel R.; Bradford, John B.

    2014-01-01

    Although arid and semiarid regions are defined by low precipitation, the seasonal timing of temperature and precipitation can influence net primary production and plant functional type composition. The importance of precipitation seasonality is evident in semiarid areas of the western U.S., which comprise the Intermountain (IM) zone, a region that receives important winter precipitation and is dominated by woody plants and the Great Plains (GP), a region that receives primarily summer precipitation and is dominated by perennial grasses. Although these general relationships are well recognized, specific differences in water cycling between these regions have not been well characterized. We used a daily time step soil water simulation model and twenty sites from each region to analyze differences in soil water dynamics and ecosystem water balance. IM soil water patterns are characterized by storage of water during fall, winter, and spring resulting in relatively reliable available water during spring and early summer, particularly in deep soil layers. By contrast, GP soil water patterns are driven by pulse precipitation events during the warm season, resulting in fluctuating water availability in all soil layers. These contrasting patterns of soil water—storage versus pulse dynamics—explain important differences between the two regions. Notably, the storage dynamics of the IN sites increases water availability in deep soil layers, favoring the deeper rooted woody plants in that region, whereas the pulse dynamics of the Great Plains sites provide water primarily in surface layers, favoring the shallow-rooted grasses in that region. In addition, because water received when plants are either not active or only partially so is more vulnerable to evaporation and sublimation than water delivered during the growing season, IM ecosystems use a smaller fraction of precipitation for transpiration (47%) than GP ecosystems (49%). Recognizing the pulse-storage dichotomy in

  2. Structure and dynamics of supercooled water in neutral confinements

    NASA Astrophysics Data System (ADS)

    Klameth, F.; Vogel, M.

    2013-04-01

    We perform molecular dynamics simulations to study the structure and dynamics of liquid water in neutral nanopores, which are generated by pinning a suitable subset of water molecules in an equilibrium configuration of a bulk system. It is found that such neutral confinement does not disturb the structure of water, in particular, the local tetrahedral order, while it imposes a pronounced spatial inhomogeneity on the dynamics of water. Specifically, when the pore wall is approached, hopping motion sets in and water dynamics slows down. We show that the logarithm of the correlation time is an exponential function of the distance to the wall, indicating a tremendous gradient of water mobility across the confinement. Upon cooling, the length scale associated with this exponential distance dependence and, thus, the range of the wall effect increases, at least down to the critical temperature of mode coupling theory, Tc. Also, the temperature dependence of water dynamics varies across the pore, i.e., fragility is high in the pore center, while it is low near the pore wall. Due to all these effects, time-temperature superposition is violated. Our observations for a neutral confinement reveal that specific interactions at hydrophilic or hydrophobic walls are not the main cause of spatially inhomogeneous dynamics of confined water. In view of similarities with the behavior of Lennard-Jones liquids in neutral confinements, one may rather speculate that the effects observed for confined water are general and result from the existence of a static contribution to the energy landscape, which is imprinted by an immobile environment.

  3. Dynamical Crossover in Hot Dense Water: The Hydrogen Bond Role.

    PubMed

    Ranieri, Umbertoluca; Giura, Paola; Gorelli, Federico A; Santoro, Mario; Klotz, Stefan; Gillet, Philippe; Paolasini, Luigi; Koza, Michael Marek; Bove, Livia E

    2016-09-01

    We investigate the terahertz dynamics of liquid H2O as a function of pressure along the 450 K isotherm, by coupled quasielastic neutron scattering and inelastic X-ray scattering experiments. The pressure dependence of the single-molecule dynamics is anomalous in terms of both microscopic translation and rotation. In particular, the Stokes-Einstein-Debye equations are shown to be violated in hot water compressed to the GPa regime. The dynamics of the hydrogen bond network is only weakly affected by the pressure variation. The time scale of the structural relaxation driving the collective dynamics increases by a mere factor of 2 along the investigated isotherm, and the structural relaxation strength turns out to be almost pressure independent. Our results point at the persistence of the hydrogen bond network in hot dense water up to ice VII crystallization, thus questioning the long-standing perception that hydrogen bonds are broken in liquid water under the effect of compression. PMID:27479235

  4. Wetting dynamics of a water nanodrop on graphene.

    PubMed

    Andrews, Joseph Eugene; Sinha, Shayandev; Chung, Peter W; Das, Siddhartha

    2016-09-14

    Water-graphene wetting interactions are central to several applications such as desalination, water filtration, electricity generation, biochemical sensing, fabrication of fuel cells, and many more. While substantial attention has been devoted to probe the wetting statics of a water drop on graphene, unraveling the possible wetting translucency nature of graphene, very little research has been done on the dynamics of wetting of water drops on graphene-coated solids or free-standing graphene layers. In this paper, we employ molecular dynamics (MD) simulations to study the contact and the spreading of a water nanodrop, quantifying its wetting dynamics, on supported and free-standing graphene. We demonstrate that nanoscale water drops establish contact with graphene by forming patches on graphene, and this patch formation is hastened for graphene layer(s) supported on hydrophilic solids. More importantly, our results demonstrate that the nanodrop spreading dynamics, regardless of the number of graphene layers or the nature of the underlying solid, obey the half-power law, i.e., r∼t(1/2) (where r is the wetting contact radius and t is the spreading time) for the entire timespan of spreading except towards the very end of the spreading lifetime when the spreading stops. Such a spreading behavior is exactly analogous to the spreading dynamics of nanodroplets for standard solids - this is in sharp contrast to the wetting statics of graphene where the wetting translucency effect makes graphene different from other standard solids. PMID:27306955

  5. Using Ethanol to Investigate Dynamic Soil Water Repellency

    NASA Astrophysics Data System (ADS)

    Smith, James E.; Beatty, Sarah M.

    2016-04-01

    Large gaps remain in our fundamental understanding of the behaviour of water in dynamically repellent soils. By investigating these systems using other miscible fluids that minimize or eliminate repellency, e.g. ethanol, we seek to better understand and quantify soil water repellency. The advantages of the enhanced wettability of water repellent soils to other miscible fluids, however, come with complications including shifts in effective pore water pressures induced through variable interfacial tensions as well as differences in fluid mobility due to variable fluid viscosities and densities. With these considerations in mind, we compare and contrast the observed behaviours of fluid infiltration and retention in dynamically hydrophobic soils and hydrophilic soils. We conducted field and laboratory studies using tension disc infiltrometers along with water and ethanol solutions to investigate dynamic repellency in post-wildfire soils from Northern Ontario, Canada. Tension infiltrometers maintain a constant negative liquid pressure at the surface which proved to be useful for isolating wettable behaviours sensitive to dynamic changes in wettability. We present the data and system conceptualised and explained through contact angle dynamics and variable fractional wettability of the soil. The limitations of extending hydrophilic concepts and hydraulic functions to hydrophobic soils are discussed along with persistent challenges to advance our ability to simulate and predict system behaviours in naturally occurring water repellent soils.

  6. Nonlinear Dynamic Characteristics of Oil-in-Water Emulsions

    NASA Astrophysics Data System (ADS)

    Yin, Zhaoqi; Han, Yunfeng; Ren, Yingyu; Yang, Qiuyi; Jin, Ningde

    2016-08-01

    In this article, the nonlinear dynamic characteristics of oil-in-water emulsions under the addition of surfactant were experimentally investigated. Firstly, based on the vertical upward oil-water two-phase flow experiment in 20 mm inner diameter (ID) testing pipe, dynamic response signals of oil-in-water emulsions were recorded using vertical multiple electrode array (VMEA) sensor. Afterwards, the recurrence plot (RP) algorithm and multi-scale weighted complexity entropy causality plane (MS-WCECP) were employed to analyse the nonlinear characteristics of the signals. The results show that the certainty is decreasing and the randomness is increasing with the increment of surfactant concentration. This article provides a novel method for revealing the nonlinear dynamic characteristics, complexity, and randomness of oil-in-water emulsions with experimental measurement signals.

  7. Molecular dynamics insights into human aquaporin 2 water channel.

    PubMed

    Binesh, A R; Kamali, R

    2015-12-01

    In this study, the first molecular dynamics simulation of the human aquaporin 2 is performed and for a better understanding of the aquaporin 2 permeability performance, the characteristics of water transport in this protein channel and key biophysical parameters of AQP2 tetramer including osmotic and diffusive permeability constants and the pore radius are investigated. For this purpose, recently recovered high resolution X-ray crystal structure of` the human aquaporin 2 is used to perform twenty nanosecond molecular dynamics simulation of fully hydrated tetramer of this protein embedded in a lipid bilayer. The resulting water permeability characteristics of this protein channel showed that the water permeability of the human AQP2 is in a mean range in comparison with other human aquaporins family. Finally, the results reported in this research demonstrate that molecular dynamics simulation of human AQP2 provided useful insights into the mechanisms of water permeation and urine concentration in the human kidney. PMID:26489820

  8. Intermittent particle dynamics in marine coastal waters

    NASA Astrophysics Data System (ADS)

    Renosh, P. R.; Schmitt, F. G.; Loisel, H.

    2015-10-01

    Marine coastal processes are highly variable over different space scales and timescales. In this paper we analyse the intermittency properties of particle size distribution (PSD) recorded every second using a LISST instrument (Laser In-Situ Scattering and Transmissometry). The particle concentrations have been recorded over 32 size classes from 2.5 to 500 μm, at 1 Hz resolution. Such information is used to estimate at each time step the hyperbolic slope of the particle size distribution, and to consider its dynamics. Shannon entropy, as an indicator of the randomness, is estimated at each time step and its dynamics is analysed. Furthermore, particles are separated into four classes according to their size, and the intermittent properties of these classes are considered. The empirical mode decomposition (EMD) is used, associated with arbitrary-order Hilbert spectral analysis (AHSA), in order to retrieve scaling multifractal moment functions, for scales from 10 s to 8 min. The intermittent properties of two other indicators of particle concentration are also considered in the same range of scales: the total volume concentration Cvol-total and the particulate beam attenuation coefficient cp(670). Both show quite similar intermittent dynamics and are characterised by the same exponents. Globally we find here negative Hurst exponents (meaning the small scales show larger fluctuation than large scales) for each time series considered, and nonlinear moment functions.

  9. Aqua Dynamics. Physical Conditioning through Water Exercises.

    ERIC Educational Resources Information Center

    President's Council on Physical Fitness and Sports, Washington, DC.

    Swimming is recognized as America's most popular active sport. It is one of the best physical activities for people of all ages and for people who are physically handicapped. Vigorous water exercises can increase a person's flexibility, strength, and cardio-vascular endurance. Exercises requiring flexibility are performed more easily in water…

  10. DOE workshop: Sedimentary systems, aqueous and organic geochemistry

    SciTech Connect

    Not Available

    1993-07-01

    A DOE workshop on sedimentary systems, aqueous and organic geochemistry was held July 15-16, 1993 at Lawrence Berkeley Laboratory. Papers were organized into several sections: Fundamental Properties, containing papers on the thermodynamics of brines, minerals and aqueous electrolyte solutions; Geochemical Transport, covering 3-D imaging of drill core samples, hydrothermal geochemistry, chemical interactions in hydrocarbon reservoirs, fluid flow model application, among others; Rock-Water Interactions, with presentations on stable isotope systematics of fluid/rock interaction, fluid flow and petotectonic evolution, grain boundary transport, sulfur incorporation, tracers in geologic reservoirs, geothermal controls on oil-reservoir evolution, and mineral hydrolysis kinetics; Organic Geochemistry covered new methods for constraining time of hydrocarbon migration, kinetic models of petroleum formation, mudstones in burial diagenesis, compound-specific carbon isotope analysis of petroleums, stability of natural gas, sulfur in sedimentary organic matter, organic geochemistry of deep ocean sediments, direct speciation of metal by optical spectroscopies; and lastly, Sedimentary Systems, covering sequence stratigraphy, seismic reflectors and diagenetic changes in carbonates, geochemistry and origin of regional dolomites, and evidence of large comet or asteroid impacts at extinction boundaries.

  11. Dynamic adhesion forces between microparticles and substrates in water.

    PubMed

    Xu, Quan; Li, Mingtao; Zhang, Lipeng; Niu, Jianbing; Xia, Zhenhai

    2014-09-23

    The interactions between micrometer-sized particles and substrates in aqueous environment are fundamental to numerous natural phenomena and industrial processes. Here we report a dynamically induced enhancement in adhesion interactions between microparticles and substrates immerged in water, air, and hexane. The dynamic adhesion force was measured by pulling microsized spheres off various substrate (hydrophilic/hydrophobic) surfaces at different retracting velocities. It was observed that when the pull-off velocity varies from 0.02 to 1500 μm/s, there is 100-200% increase in adhesion force in water while it has a 100% increase in nitrogen and hexane. The dynamic adhesion enhancement reduces with increasing effective contact angle defined by the average cosine of wetting angles of the substrates and the particles, and approaches the values measured in dry nitrogen and hexane as the effective contact angle is larger than 90(o). A dynamic model was developed to predict the adhesion forces resulting from this dynamic effect, and the predictions correlate well with the experimental results. The stronger dynamic adhesion enhancement in water is mainly attributed to electrical double layers and the restructuring of water in the contact area between particles and substrates. PMID:25162139

  12. Sulfide Mineralogy and Geochemistry

    NASA Astrophysics Data System (ADS)

    Dilles, John

    2007-02-01

    Reviews in Mineralogy and Geochemistry Series, Volume 61 David J. Vaughan, Editor Geochemical Society and Mineralogical Society of America; ISBN 0-939950-73-1 xiii + 714 pp.; 2006; $40. Sulfide minerals as a class represent important minor rock-forming minerals, but they are generally known as the chief sources of many economic metallic ores. In the past two decades, sulfide research has been extended to include important roles in environmental geology of sulfide weathering and resultant acid mine drainage, as well as in geomicrobiology in which bacteria make use of sulfides for metabolic energy sources. In the latter respect, sulfides played an important role in early evolution of life on Earth and in geochemical cycling of elements in the Earth's crust and hydrosphere.

  13. Reservoir geochemistry: A link between reservoir geology and engineering?

    SciTech Connect

    Larter, S.R.; Aplin, A.C.; Corbett, P.; Ementon, N.

    1994-12-31

    Geochemistry provides a natural but poorly exploited link between reservoir geology and engineering. The authors summarize some current applications of geochemistry to reservoir description and stress that because of their strong interactions with mineral surfaces and water, nitrogen and oxygen compounds in petroleum may exert an important influence on the PVT properties of petroleum, viscosity and wettability. The distribution of these compounds in reservoirs is heterogeneous on a sub-meter scale and is partly controlled by variations in reservoir quality. The implied variations in petroleum properties and wettability may account for some of the errors in reservoir simulations.

  14. Reservoir geochemistry: A link between reservoir geology and engineering?

    SciTech Connect

    Larter, S.R.; Aplin, A.C.; Chen, M.; Taylor, P.N.; Corbett, P.W.M.; Ementon, N.

    1997-02-01

    Geochemistry provides a natural, but poorly exploited, link between reservoir geology and engineering. The authors summarize some current applications of geochemistry to reservoir description and stress that, because of their strong interactions with mineral surfaces and water, nitrogen and oxygen compounds in petroleum may exert an important influence on the pressure/volume/temperature (PVT) properties of petroleum, viscosity and wettability. The distribution of these compounds in reservoirs is heterogeneous on a submeter scale and is partly controlled by variations in reservoir quality. The implied variations in petroleum properties and wettability may account for some of the errors in reservoir simulations.

  15. On rotational dynamics of an NH4+ ion in water

    SciTech Connect

    Chang, Tsun-Mei; Dang, Liem X. )

    2003-05-15

    We used molecular dynamics simulations to characterize the rotational dynamics of the NH4+ ion in liquid water. The polarizable potential models were to describe the ion-water and water-water interactions. This study complements the work of Karim and Haymet (J. Chem. Phys., 93, 5961, 1990), who employed effective pir potential models. The computed rotational diffusion coefficients of the NH4+ ion in water, which were determined from the angular momentum autocorrelation function and the angular mean-square displacement, are 0.093 x 1012 rad2/s and 0.067 x 1012 rad2/s, repectively. These results are in good agreement with the 0.075 x 1012 rad2/s value determined from the nuclear magnetic resonance (NMR) spectroscopy studies of Perrin and Gipe (J. Am. Chem. Soc., 108, 1088, 1986; Science, 238, 1393, 1987).

  16. Statistical Analysis of Major Ion and Trace Element Geochemistry of Water, 1986-2006, at Seven Wells Transecting the Freshwater/Saline-Water Interface of the Edwards Aquifer, San Antonio, Texas

    USGS Publications Warehouse

    Mahler, Barbara J.

    2008-01-01

    This report by the U.S. Geological Survey, in cooperation with the San Antonio Water System, describes the results of a statistical analysis of major ion and trace element geochemistry of water at seven wells transecting the freshwater/saline-water interface of the Edwards aquifer in San Antonio, Texas, either over time or in response to variations in hydrologic conditions. The data used in this report were collected during 1986-2006. The seven monitoring wells are screened at different depths in the aquifer at three sites that form a generally north-to-south transect. The three wells of the southern site and the deeper of the two middle-site wells are open to the freshwater/saline-water transition zone, which contains saline water. The shallower well of the middle site and the two wells of the northern site are open to the freshwater zone. Mean specific conductance (SC) values were greater at transition-zone wells than at freshwater-zone wells, but SC did not vary systematically with depth. Concentrations of all major ions except bicarbonate were greater at transition-zone wells than at freshwater-zone wells, but concentrations tended to be more variable at freshwater-zone wells. Mean molar ratios of magnesium:calcium, sulfate:chloride, and sodium:chloride were similar at transition-zone wells and freshwater-zone wells. Concentrations of trace elements for many water samples at the seven transect wells were below the laboratory analytical reporting level. Detections of trace elements were more frequent at transition-zone wells, and mean concentrations of cadmium, chromium, copper, lead, and silver were elevated at transition-zone wells relative to freshwater-zone wells. All strong correlations between SC and major ions were positive, and in general there were more and stronger correlations between SC and major ions in the water from the freshwater-zone wells than from the transition-zone wells. Except for the shallowest transition-zone well, the transition

  17. Orientational dynamics of water at an extended hydrophobic interface

    NASA Astrophysics Data System (ADS)

    Figge, Florian; Xiao, Shunhao; McGuire, John A.; Stirnemann, Guillaume; Laage, Damien

    Aqueous interfaces are central to many physical processes, but the dynamics of interfacial water molecules have been little studied. We have measured the orientational dynamics of water at its interface with a self-assembled monolayer of octadecylsilane on fused silica. A surface-sensitive sum-frequency probe generated by mixing a visible and a vibrationally resonant infrared (IR) pulse is used to monitor the dangling (non-hydrogen-bonded) OH stretch vibration after excitation with a resonant IR pump pulse. By measuring pure and isotopically diluted water with orthogonal pump polarizations, we find that relaxation of the dangling OH stretch excitation is dominated by the out-of-plane jump from a dangling to a hydrogen-bonded configuration and the subsequent redistribution of energy from the surface hydrogen-bonded OH stretch excitation. The out-of-plane jump time is 1.5(1)ps, 30% slower than that reported for the air-water interface and twice as short as the jump time between hydrogen bonded configurations in the bulk. Molecular dynamics simulations indicate that the slower dynamics at the hydrophobic interface compared to the water-air interface are due to the hydrogen bonds at the hydrophobic interface being stronger than those at the water-air interface. The authors acknowledge support from the National Science Foundation (Grant No. CHE- 1151590).

  18. Orientational Dynamics of Water at an Extended Hydrophobic Interface.

    PubMed

    Xiao, Shunhao; Figge, Florian; Stirnemann, Guillaume; Laage, Damien; McGuire, John A

    2016-05-01

    We report on the orientational dynamics of water at an extended hydrophobic interface with an octadecylsilane self-assembled monolayer on fused silica. The interfacial dangling OH stretch mode is excited with a resonant pump, and its evolution followed in time by a surface-specific, vibrationally resonant, infrared-visible sum-frequency probe. High sensitivity pump-probe anisotropy measurements and isotopic dilution clearly reveal that the decay of the dangling OH stretch excitation is almost entirely due to a jump to a hydrogen-bonded configuration that occurs in 1.61 ± 0.10 ps. This is more than twice as fast as the jump time from one hydrogen-bonded configuration to another in bulk H2O but about 50% slower than the reported out-of-plane reorientation at the air/water interface. In contrast, the intrinsic population lifetime of the dangling OH stretch in the absence of such jumps is found to be >10 ps. Molecular dynamics simulations of air/water and hexane/water interfaces reproduce the fast jump dynamics of interfacial dangling OH with calculated jump times of 1.4 and 1.7 ps for the air and hydrophobic interfaces, respectively. The simulations highlight that while the air/water and hydrophobic/water surfaces exhibit great structural similarities, a small stabilization of the OH groups by the hydrophobic interface produces the pronounced difference in the dynamics of dangling bonds. PMID:27045950

  19. Dynamics of water in prussian blue analogues: Neutron scattering study

    NASA Astrophysics Data System (ADS)

    Sharma, V. K.; Mitra, S.; Thakur, N.; Yusuf, S. M.; Juranyi, Fanni; Mukhopadhyay, R.

    2014-07-01

    Dynamics of crystal water in Prussian blue (PB), Fe(III)4[Fe(II)(CN)6]3.14H2O and its analogue Prussian green (PG), ferriferricynaide, Fe(III)4[Fe(III)(CN)6]4.16H2O have been investigated using Quasielastic Neutron Scattering (QENS) technique. PB and its analogue compounds are important materials for their various interesting multifunctional properties. It is known that crystal water plays a crucial role towards the multifunctional properties of Prussian blue analogue compounds. Three structurally distinguishable water molecules: (i) coordinated water molecules at empty nitrogen sites, (ii) non-coordinated water molecules in the spherical cavities, and (iii) at interstitial sites exist in PB. Here spherical cavities are created due to the vacant sites of Fe(CN)6 units. However, PG does not have any such vacant N or Fe(CN)6 units, and only one kind of water molecules, exists only at interstitial sites. QENS experiments have been carried out on both the compounds in the temperature range of 260-360 K to elucidate the dynamical behavior of different kinds of water molecules. Dynamics is found to be much more pronounced in case of PB, compared to PG. A detailed data analysis showed that localized translational diffusion model could describe the observed data for both PB and PG systems. The average diffusion coefficient is found to be much larger in the PB than PG. The obtained domain of dynamics is found to be consistent with the geometry of the structure of the two systems. Combining the data of the two systems, a quantitative estimate of the dynamics, corresponding to the water molecules at different locations is made.

  20. Dynamics of water in prussian blue analogues: Neutron scattering study

    SciTech Connect

    Sharma, V. K.; Mitra, S.; Thakur, N.; Yusuf, S. M.; Mukhopadhyay, R.; Juranyi, Fanni

    2014-07-21

    Dynamics of crystal water in Prussian blue (PB), Fe(III){sub 4}[Fe(II)(CN){sub 6}]{sub 3}.14H{sub 2}O and its analogue Prussian green (PG), ferriferricynaide, Fe(III){sub 4}[Fe(III)(CN){sub 6}]{sub 4}.16H{sub 2}O have been investigated using Quasielastic Neutron Scattering (QENS) technique. PB and its analogue compounds are important materials for their various interesting multifunctional properties. It is known that crystal water plays a crucial role towards the multifunctional properties of Prussian blue analogue compounds. Three structurally distinguishable water molecules: (i) coordinated water molecules at empty nitrogen sites, (ii) non-coordinated water molecules in the spherical cavities, and (iii) at interstitial sites exist in PB. Here spherical cavities are created due to the vacant sites of Fe(CN){sub 6} units. However, PG does not have any such vacant N or Fe(CN){sub 6} units, and only one kind of water molecules, exists only at interstitial sites. QENS experiments have been carried out on both the compounds in the temperature range of 260–360 K to elucidate the dynamical behavior of different kinds of water molecules. Dynamics is found to be much more pronounced in case of PB, compared to PG. A detailed data analysis showed that localized translational diffusion model could describe the observed data for both PB and PG systems. The average diffusion coefficient is found to be much larger in the PB than PG. The obtained domain of dynamics is found to be consistent with the geometry of the structure of the two systems. Combining the data of the two systems, a quantitative estimate of the dynamics, corresponding to the water molecules at different locations is made.

  1. Hydration water dynamics and instigation of protein structuralrelaxation

    SciTech Connect

    Russo, Daniela; Hura, Greg; Head-Gordon, Teresa

    2003-09-01

    Until a critical hydration level is reached, proteins do not function. This critical level of hydration is analogous to a similar lack of protein function observed for temperatures below a dynamical temperature range of 180-220K that also is connected to the dynamics of protein surface water. Restoration of some enzymatic activity is observed in partially hydrated protein powders, sometimes corresponding to less than a single hydration layer on the protein surface, which indicates that the dynamical and structural properties of the surface water is intimately connected to protein stability and function. Many elegant studies using both experiment and simulation have contributed important information about protein hydration structure and timescales. The molecular mechanism of the solvent motion that is required to instigate the protein structural relaxation above a critical hydration level or transition temperature has yet to be determined. In this work we use experimental quasi-elastic neutron scattering (QENS) and molecular dynamics simulation to investigate hydration water dynamics near a greatly simplified protein system. We consider the hydration water dynamics near the completely deuterated N-acetyl-leucine-methylamide (NALMA) solute, a hydrophobic amino acid side chain attached to a polar blocked polypeptide backbone, as a function of concentration between 0.5M-2.0M under ambient conditions. We note that roughly 50-60% of a folded protein's surface is equally distributed between hydrophobic and hydrophilic domains, domains whose lengths are on the order of a few water diameters, that justify our study of hydration dynamics of this simple model protein system. The QENS experiment was performed at the NIST Center for Neutron Research, using the disk chopper time of flight spectrometer (DCS). In order to separate the translational and rotational components in the spectra, two sets of experiments were carried out using different incident neutron wavelengths of 7

  2. Quantum effects in the dynamics of deeply supercooled water

    SciTech Connect

    Agapov, Alexander L.; Kolesnikov, Alexander I.; Novikov, Vladimir N.; Richert, Ranko; Sokolov, Alexei P

    2015-02-26

    In spite of its simple chemical structure, water remains one of the most puzzling liquids with many anomalies at low temperatures. Combining neutron scattering and dielectric relaxation spectroscopy, we show that quantum fluctuations are not negligible in deeply supercooled water. Our dielectric measurements reveal the anomalously weak temperature dependence of structural relaxation in vapor-deposited water close to the glass transition temperature Tg~136K. We demonstrate that this anomalous behavior can be explained well by quantum effects. In conclusion, these results have significant implications for our understanding of water dynamics.

  3. Quantum effects in the dynamics of deeply supercooled water

    DOE PAGESBeta

    Agapov, Alexander L.; Kolesnikov, Alexander I.; Novikov, Vladimir N.; Richert, Ranko; Sokolov, Alexei P

    2015-02-26

    In spite of its simple chemical structure, water remains one of the most puzzling liquids with many anomalies at low temperatures. Combining neutron scattering and dielectric relaxation spectroscopy, we show that quantum fluctuations are not negligible in deeply supercooled water. Our dielectric measurements reveal the anomalously weak temperature dependence of structural relaxation in vapor-deposited water close to the glass transition temperature Tg~136K. We demonstrate that this anomalous behavior can be explained well by quantum effects. In conclusion, these results have significant implications for our understanding of water dynamics.

  4. Nonequilibrium water dynamics in the rhizosphere: How mucilage affects water flow in soils

    NASA Astrophysics Data System (ADS)

    Kroener, Eva; Zarebanadkouki, Mohsen; Kaestner, Anders; Carminati, Andrea

    2014-08-01

    The flow of water from soil to plant roots is controlled by the properties of the narrow region of soil close to the roots, the rhizosphere. In particular, the hydraulic properties of the rhizosphere are altered by mucilage, a polymeric gel exuded by the roots. In this paper we present experimental results and a conceptual model of water flow in unsaturated soils mixed with mucilage. A central hypothesis of the model is that the different drying/wetting rate of mucilage compared to the bulk soil results in nonequilibrium relations between water content and water potential in the rhizosphere. We coupled this nonequilibrium relation with the Richards equation and obtained a constitutive equation for water flow in soil and mucilage. To test the model assumptions, we measured the water retention curve and the saturated hydraulic conductivity of sandy soil mixed with mucilage from chia seeds. Additionally, we used neutron radiography to image water content in a layer of soil mixed with mucilage during drying and wetting cycles. The radiographs demonstrated the occurrence of nonequilibrium water dynamics in the soil-mucilage mixture. The experiments were simulated by numerically solving the nonequilibrium model. Our study provides conceptual and experimental evidences that mucilage has a strong impact on soil water dynamics. During drying, mucilage maintains a greater soil water content for an extended time, while during irrigation it delays the soil rewetting. We postulate that mucilage exudation by roots attenuates plant water stress by modulating water content dynamics in the rhizosphere.

  5. Slow dynamics of supercooled water confined in nanoporous silica materials

    NASA Astrophysics Data System (ADS)

    Liu, L.; Faraone, A.; Mou, C.-Y.; Yen, C.-W.; Chen, S.-H.

    2004-11-01

    We review our incoherent quasielastic neutron scattering (QENS) studies of the dynamics of supercooled water confined in nanoporous silica materials. QENS data were analysed by using the relaxing cage model (RCM) previously developed by us. We first use molecular dynamics (MD) simulation of the extended simple point charge model (SPC/E) for bulk supercooled water to establish the validity of the RCM, which applies to both the translational and rotational motion of water molecules. We then assume that the dynamics of water molecules in the vicinity of a hydrophilic surface is similar to a bulk water at an equivalent lower supercooled temperature. This analogy was experimentally demonstrated in previous investigations of water in Vycor glasses and near hydrophilic protein surfaces. Studies were made of supercooled water in MCM-41-S (pore sizes 25, 18, and 14 Å) and MCM-48-S (pore size 22 Å) using three QENS spectrometers of respective energy resolutions 1, 30, and 60 µeV, covering the temperature range from 325 to 200 K. Five quantities are extracted from the analysis: they are β, the stretch exponent characterizing the α-relaxation βγ, the exponent determining the power-law dependence of the relaxation time on Q; \\langle \\tau_{0} \\rangle , the Q-independent pre-factor for the average translational relaxation time; \\langle \\tau _{{\\mathrm {R}}_{1}} \\rangle , the relaxation time for the first-order rotational correlation function; and \\langle \\tau _{{\\mathrm {R}}_{2}} \\rangle , the relaxation time for the second-order rotational correlation function. We discuss the temperature dependence of these parameters and note that, in particular, the dynamics is rapidly slowing down at temperature around 220 K, signalling the onset of a structural arrest transition of liquid water into an amorphous solid water.

  6. Dissolution dynamics of the calcite-water interface observed in situ by glancing-incidence X-ray scattering

    SciTech Connect

    Sturchio, N.C.; Chiarello, R.P.

    1995-06-02

    Glancing-incidence X-ray scattering measurements made at the National Synchrotron Light Source were used to investigate dissolution dynamics in situ at the calcite-water interface. The relation between calcite saturation state and roughness of the calcite (1014) cleavage surface as a function of time was examined during pH titrations of an initially calcite-saturated solution. Systematic variations in roughness were observed as a function of saturation state as pH was titrated to values below that of calcite saturation. Different steady-state values of roughness were evident at fixed values of {Delta}G{sub r}, and these were correlated with the extent of undersaturation. A significant increase in roughness begins to occur with increasing undersaturation at a {Delta}G{sub r} value of approximately {minus}2.0 kcal/mol. The dissolution rate corresponding to this increase is about 1.5 x 10{sup 7} mmol/cm {center_dot} sec. This increase in roughness is attributed to a transition in the principal rate-determining dissolution mechanism, and is consistent with both powder-reaction studies of dissolution kinetics and single-crystal dissolution studies by atomic force microscopy. These data indicate some important potential applications of GIXS in the study of mineral-water interface geochemistry.

  7. Dynamic response of surface water-groundwater exchange to currents, tides, and waves in a shallow estuary

    NASA Astrophysics Data System (ADS)

    Sawyer, Audrey H.; Shi, Fengyan; Kirby, James T.; Michael, Holly A.

    2013-04-01

    In shallow, fetch-limited estuaries, variations in current and wave energy promote heterogeneous surface water-groundwater mixing (benthic exchange), which influences biogeochemical activity. Here, we characterize heterogeneity in benthic exchange within the subtidal zone of the Delaware Inland Bays by linking hydrodynamic circulation models with mathematical solutions for benthic exchange forced by current-bedform interactions, tides, and waves. Benthic fluxes oscillate over tidal cycles as fluctuating water depths alter fluid interactions with the bed. Maximum current-driven fluxes (~1-10 cm/d) occur in channels with strong tidal currents. Maximum wave-driven fluxes (~1-10 cm/d) occur in downwind shoals. During high-energy storms, simulated wave pumping rates increase by orders of magnitude, demonstrating the importance of storms in solute transfer through the benthic layer. Under moderate wind conditions (~5 m/s), integrated benthic exchange rates due to wave, current, and tidal pumping are each ~1-10 m3/s, on the order of fluid contributions from runoff and fresh groundwater discharge to the estuary. Benthic exchange is thus a significant and dynamic component of an estuary's fluid budget that may influence estuarine geochemistry and ecology.

  8. Water and polymer dynamics in highly crosslinked polyamide membranes

    NASA Astrophysics Data System (ADS)

    Frieberg, Bradley; Chan, Edwin; Tyagi, Madhu; Stafford, Christopher; Soles, Christopher

    Highly crosslinked polyamides for reverse osmosis are the state-of-the-art active material in membranes for desalination. The thin film composite membrane structure that is used commercially has been empirically designed to selectively allow the passage of water molecules and minimize the passage of solutes such as salt. However, due to the large roughness and variability of the polyamide layer, there is a limited understanding of the structure-property relationship for these materials as well as the transport mechanism. To better understand the water transport mechanism we measure the water and polymer dynamics of polyamide membranes using quasi-elastic neutron scattering (QENS). By hydrating the membrane with deuterated water, we are able to isolate the dynamics of the hydrogenated membrane on the pico- and nanosecond time scales. By subsequently hydrating the membranes with hydrogenated water, the QENS measurements on the same times scales reveal information about both the translational and rotational dynamics of water confined within the polyamide membrane. Further understanding of the water diffusion mechanism will establish design rules in which the performance of future membrane materials can be improved.

  9. Imaging the molecular dynamics of dissociative electron attachment to water

    SciTech Connect

    Adaniya, Hidihito; Rudek, B.; Osipov, Timur; Haxton, Dan; Weber, Thorsten; Rescigno, Thomas N.; McCurdy, C.W.; Belkacem, Ali

    2009-10-19

    Momentum imaging experiments on dissociative electron attachment to the water molecule are combined with ab initio theoretical calculations of the angular dependence of the quantum mechanical amplitude for electron attachment to provide a detailed picture of the molecular dynamics of dissociation attachment via the two lowest energy Feshbach resonances. The combination of momentum imaging experiments and theory can reveal dissociation dynamics for which the axial recoil approximation breaks down and thus provides a powerful reaction microscope for DEA to polyatomics.

  10. Quantum tunneling and vibrational dynamics of ultra-confined water

    NASA Astrophysics Data System (ADS)

    Kolesnikov, Alexander I.; Anovitz, Lawrence M.; Ehlers, Georg; Mamontov, Eugene; Podlesnyak, Andrey; Prisk, Timothy R.; Seel, Andrew; Reiter, George F.

    2015-03-01

    Vibrational dynamics of ultra-confined water in single crystals beryl, the structure of which contains ~ 5 Å diameter channels along the c-axis was studied with inelastic (INS), quasi-elastic (QENS) and deep inelastic (DINS) neutron scattering. The results reveal significantly anisotropic dynamical behavior of confined water, and show that effective potential experienced by water perpendicular to the channels is significantly softer than along them. The observed 7 peaks in the INS spectra (at energies 0.25 to 15 meV), based on their temperature and momentum transfer dependences, are explained by transitions between the split ground states of water in beryl due to water quantum tunneling between the 6-fold equivalent positions across the channels. DINS study of beryl at T=4.3 K shows narrow, anisotropic water proton momentum distribution with corresponding kinetic energy, EK=95 meV, which is much less than was previously observed in bulk water (~150 meV). We believe that the exceptionally small EK in beryl is a result of water quantum tunneling ∖ delocalization in the nanometer size confinement and weak water-cage interaction. The neutron experiment at ORNL was sponsored by the Sci. User Facilities Div., BES, U.S. DOE. This research was sponsored by the Div. Chemical Sci, Geosciences, and Biosciences, BES, U.S. DOE. The STFC RAL is thanked for access to ISIS neutron facilities.

  11. Arctic Pacific water dynamics from model intercomparison and observations

    NASA Astrophysics Data System (ADS)

    Aksenov, Yevgeny; Karcher, Michael; Proshutinsky, Andrey; Gerdes, Ruediger; Bacon, Sheldon; Nurser, George; Coward, Andrew; Golubeva, Elena; Kauker, Frank; Nguyen, An; Platov, Gennady; Wadley, Martin; Watanabe, Eiji

    2016-04-01

    Pacific Water imports heat and fresh water from the northern Pacific in the Arctic Ocean, impacting upper ocean mixing and dynamics, as well as Arctic sea ice. Pathways and the circulation of PW in the central Arctic Ocean are not well known due to the lack of observations. This study uses an ensemble of the sea ice-ocean models integrated with passive tracer released in the Bering Strait to simulate Pacific water spread. We investigate different branches and modes of Pacific water and analyse changes in the water mass distribution through the Arctic Ocean due to changes in the wind and ocean potential vorticity. We focus on seasonal cycle and inter-decadal variations. The first results have been published recently (Aksenov et al., 2015) as a part of Forum for Arctic Ocean Modeling and Observational Synthesis (FAMOS) project. In the present study we extend the examination further and discuss the role of the Pacific water variability in the recent changes in the Arctic heat and fresh water storage. We present insights in the projected future changes to Pacific water dynamics. Reference Aksenov, Y., et al. (2015), Arctic pathways of Pacific Water: Arctic Ocean Model Intercomparison experiments, J. Geophys. Res. Oceans, 120, doi:10.1002/2015JC011299.

  12. Dynamical evolution of sand ripples under water.

    PubMed

    Stegner, A; Wesfreid, J E

    1999-10-01

    We have performed an experimental study on the evolution of sand ripples formed under the action of an oscillatory flow. An annular sand-water cell was used in order to investigate a wide range of parameters. The sand ripples follow an irreversible condensation mechanism from small to large wavelength until a final state is reached. The wavelength and the shape of these stable sand patterns are mainly governed by the fluid displacement and the static angle of the granular media. A strong hysteresis affects the evolution of steep ripples. When the acceleration of the sand bed reaches a critical value, the final pattern is modified by the superficial fluidization of the sand layer. PMID:11970264

  13. Water exchange dynamics around H3O+ and OH- ions

    NASA Astrophysics Data System (ADS)

    Roy, Santanu; Dang, Liem X.

    2015-05-01

    In this letter, we report the first computer simulation of the dynamics of water exchanging between the first and second solvation shells of H3O+. Employing different rate theories for chemical reactions such as the transition state theory, the Grote-Hynes theory, the reactive flux method, and the Impey-Madden-McDonald method, we calculate the solvent exchange rates from molecular dynamics simulations that account for explicit polarization effects. In addition, we also study water exchanges around OH- and find that the corresponding time scale is much smaller than that for H3O+.

  14. Hydration water in dynamics of a hydrated beta-lactoglobulin

    NASA Astrophysics Data System (ADS)

    Yoshida, K.; Yamaguchi, T.; Bellissent-Funel, M.-C.; Longeville, S.

    2007-02-01

    Incoherent spin-echo signals of a hydrated β-lactoglobulin protein were investigated, at 275 and 293 K. The intermediate scattering functions I(Q,t) were divided in two contributions from surface water and protein, respectively. On one hand, the dynamics of the surface water follows a KWW stretched exponential function (the exponent is ~0.5), on the other hand, that of the protein follows a single exponential. The present results are consistent with our previous results of hydrated C-phycocyanin combining elastic and quasielastic neutron scattering and by molecular dynamics simulation.

  15. Dynamics of lysozyme and its hydration water under electric field

    SciTech Connect

    Favi, Pelagie M; Zhang, Qiu; O'Neill, Hugh Michael; Mamontov, Eugene; Omar Diallo, Souleymane; Palmer, Jeremy

    2014-01-01

    The effects of static electric field on the dynamics of lysozyme and its hydration water have been investigated by means of incoherent quasi-elastic neutron scattering (QENS). Measurements were performed on lysozyme samples, hydrated respectively with heavy water (D2O) to capture the protein dynamics, and with light water (H2O), to probe the dynamics of the hydration shell, in the temperature range from 210 < T < 260 K. The hydration fraction in both cases was about 0.38 gram of water per gram of dry protein. The field strengths investigated were respectively 0 kV/mm and 2 kV/mm ( 2 106 V/m) for the protein hydrated with D2O and 0 kV and 1 kV/mm for the H2O-hydrated counterpart. While the overall internal protons dynamics of the protein appears to be unaffected by the application of electric field up to 2 kV/mm, likely due to the stronger intra-molecular interactions, there is also no appreciable quantitative enhancement of the diffusive dynamics of the hydration water, as would be anticipated based on our recent observations in water confined in silica pores under field values of 2.5 kV/mm. This may be due to the difference in surface interactions between water and the two adsorption hosts (silica and protein), or to the existence of a critical threshold field value Ec 2 3 kV/mm for increased molecular diffusion, for which electrical breakdown is a limitation for our sample.

  16. Linking Water Table Dynamics to Carbon Cycling in Artificial Soil Column Incubations

    NASA Astrophysics Data System (ADS)

    Geertje, Pronk; Adrian, Mellage; Tatjana, Milojevic; Fereidoun, Rezanezhad; Cappellen Philippe, Van

    2016-04-01

    The biogeochemistry of wetlands soils is closely tied to their hydrology. Water table fluctuations that cause flooding and drying of these systems may lead to enhanced degradation of organic matter and release of greenhouse gasses (e.g. CO2, CH4) to the atmosphere. However, predicting the influence of water table fluctuations on the biogeochemical functioning of soils requires an understanding of the interactions of soil hydrology with biogeochemical and microbial processes. To determine the effects of water table dynamics on carbon cycling, we are carrying out state-of-the-art automated soil column experiments with fully integrated monitoring of hydro-bio-geophysical process variables under both constant and oscillating water table conditions. An artificial, homogeneous mixture consisting of minerals and organic matter is used to provide a well-defined starting material. The artificial soils are composed of quartz sand, montmorillonite, goethite and humus from a forested riparian zone, from which we also extracted the microbial inoculum added to the soil mixture. The artificial soils are packed into 60 cm high, 7.5 cm wide columns. In the currently ongoing experiment, three replicate columns are incubated while keeping the water table constant water at mid-depth, while another three columns alternate between drained and saturated conditions. Micro-sensors installed at different depths below the soil surface record time-series redox potentials (Eh) varying between oxidizing (~+700 mV) and reducing (~-200 mV) conditions. Continuous O2 levels throughout the soil columns are monitored using high-resolution, luminescence-based, Multi Fiber Optode (MuFO) microsensors. Pore waters are collected periodically with MicroRhizon samplers from different depths, and analyzed for pH, EC, dissolved inorganic and organic carbon and ion/cation compositions. These measurements allow us to track the changes in pore water geochemistry and relate them to differences in carbon cycling

  17. Water Table Dynamics of a Canadian Rocky Mountain Peat Floodplain

    NASA Astrophysics Data System (ADS)

    Westbrook, C. J.

    2008-12-01

    Floodplains of broad mountain valleys serve as collection points for local precipitation, hillslope runoff, deeper groundwater, and channel water. Little is known about how complex hydrological interactions among these water sources govern floodplain water table dynamics, particularly on an event basis partly owing to a lack of high frequency spatial and temporal data. Here I describe the magnitude and rate of change of groundwater storage in a Canadian Rocky Mountain peat floodplain. Weekly manual measurement of groundwater levels in a network of 51 water table wells during the summers of 2006 and 2007 showed large temporal and spatial variations in well response. Cluster analysis and principle components analysis were performed on these data to objectively classify the floodplain into spatial response units. Results were classification of the standpipes into five distinct water table regimes. One well representing each water table regime was outfitted with a sensor in 2008 that collected hourly head, which was used to characterize temporal patterns of water table response. Preliminary results indicate a constant increase in heterogeneity in the spatial pattern of the water table as the floodplain dried. In spring, snowmelt runoff combined with an ice lens 20-30 cm below the ground surface led to consistently high water tables throughout the floodplain. Water table regime responses to rain events during this period were flashy, with dramatic rises and falls (up to 20 cm) in short periods of time (<30 h), suggesting the unsaturated zone was close to saturation. In summer, the water table fell throughout the floodplain in response to declining hillslope inputs and increased evaporative demand, but rates of decline were highly variable among the water table regimes. This variability reflects differences in the degree to which the water table regimes are influenced by stream stage, hillslope inputs, and proximity to beaver dams. Results from this study have

  18. Dielectric spectroscopy study of water dynamics in frozen bovine milk.

    PubMed

    Agranovich, Daniel; Ben Ishai, Paul; Katz, Gil; Bezman, Dror; Feldman, Yuri

    2016-05-01

    Bovine milk is a complex colloidal liquid exhibiting a multi-scaled structure. It is of particular importance, both commercially and scientifically, to investigate both its dynamic and structural properties. In the current study we have employed the broadband dielectric spectroscopy (BDS) technique in the frequency range of 10(-1)-10(6)Hz and the temperature range of 176-230 K in order to examine the molecular structure and dynamics of quenched bovine milk. Four dielectric relaxation processes were identified. Three of them are associated with water in its different forms: water-lactose complexes, bulk hexagonal and cubic ices. The fourth process is attributed to domain wall relaxations linked to the presence of micro-cracks in the ice structures. In addition, the first process, attributed to water-lactose complexes, obeys the Meyer-Neldel compensation law and can be taken as evidence of differing interfaces of these complexes with the bulk water of the milk, mediated by the lactose concentration. Furthermore, an intriguing structural-dynamic transition around 200K was observed. Considering the mentioned above, we conclude that our results emphasize the structural and dynamical significance of water in bovine milk. PMID:26878290

  19. Low dimensional molecular dynamics of water inside a carbon nanotube

    NASA Astrophysics Data System (ADS)

    Shiomi, Junichiro; Lin, Yuan; Amberg, Gustav; Maruyama, Shigeo

    2008-11-01

    While carbon nanotubes (CNTs) have attracted a number of researches as the key building blocks for nanotechnology, they have also caught attentions as ideal materials that realize quasi-one-dimensional channel environment, a key system in bioscience. Such materials stimulate studies in fluid dynamics under low dimensional confinement, which is restricted and departs significantly from that in three-dimension. The current study serves to explore such atomic scale dynamics by performing a series of molecular dynamics (MD) simulations on water confined in a CNT with a diameter of the order of 1 nm. The MD simulations have successfully probed the phase transition of a water cluster confined in a CNT to an ice-nanotube with anomalous diameter dependence. It has also been applied to investigate the possibility of transporting water through a CNT by a temperature gradient. In this study, we particularly highlight the dielectric properties of water confined inside a CNT. The confinement gives rise to strongly anisotropic dielectric relaxation, where the relaxation becomes faster and slower in the cross sectional and axial directions, respectively. The diameter dependences of the dielectric properties are discussed in connection with water dynamics and structures in quasi-one-dimension.

  20. From single molecules to water networks: Dynamics of water adsorption on Pt(111).

    PubMed

    Naderian, Maryam; Groß, Axel

    2016-09-01

    The adsorption dynamics of water on Pt(111) was studied using ab initio molecular dynamics simulations based on density functional theory calculations including dispersion corrections. Sticking probabilities were derived as a function of initial kinetic energy and water coverage. In addition, the energy distribution upon adsorption was monitored in order to analyze the energy dissipation process. We find that on the water pre-covered surface the sticking probability is enhanced because of the attractive water-water interaction and the additional effective energy dissipation channels to the adsorbed water molecules. The water structures forming directly after the adsorption on the pre-covered surfaces do not necessarily correspond to energy minimum structures. PMID:27609006

  1. Temporal dynamics of blue and green virtual water trade networks

    NASA Astrophysics Data System (ADS)

    Konar, M.; Dalin, C.; Hanasaki, N.; Rinaldo, A.; Rodriguez-Iturbe, I.

    2012-12-01

    Global food security increasingly relies on the trade of food commodities. Freshwater resources are essential to agricultural production and are thus embodied in the trade of food commodities, referred to as "virtual water trade." Agricultural production predominantly relies on rainwater (i.e., "green water"), though irrigation (i.e., "blue water") does play an important role. These different sources of water have distinctly different opportunity costs, which may be reflected in the way these resources are traded. Thus, the temporal dynamics of the virtual water trade networks from these distinct water sources require characterization. We find that 42 × 109 m3 blue and 310 × 109 m3 green water was traded in 1986, growing to 78 × 109 m3 blue and 594 × 109 m3 green water traded in 2008. Three nations dominate the export of green water resources: the USA, Argentina, and Brazil. As a country increases its export trade partners it tends to export relatively more blue water. However, as a country increases its import trade partners it does not preferentially import water from a specific source. The amount of virtual water that a country imports by increasing its import trade partners has been decreasing over time, with the exception of the soy trade. Both blue and green virtual water networks are efficient: 119 × 109 m3 blue and 105 × 109 m3 green water were saved in 2008. Importantly, trade has been increasingly saving water over time, due to the intensification of crop trade on more water-efficient links.

  2. Temporal dynamics of blue and green virtual water trade networks

    NASA Astrophysics Data System (ADS)

    Konar, M.; Dalin, C.; Hanasaki, N.; Rinaldo, A.; Rodriguez-Iturbe, I.

    2012-07-01

    Global food security increasingly relies on the trade of food commodities. Freshwater resources are essential to agricultural production and are thus embodied in the trade of food commodities, referred to as "virtual water trade." Agricultural production predominantly relies on rainwater (i.e., "green water"), though irrigation (i.e., "blue water") does play an important role. These different sources of water have distinctly different opportunity costs, which may be reflected in the way these resources are traded. Thus, the temporal dynamics of the virtual water trade networks from these distinct water sources require characterization. We find that 42 × 109 m3 blue and 310 × 109 m3 green water was traded in 1986, growing to 78 × 109 m3 blue and 594 × 109 m3 green water traded in 2008. Three nations dominate the export of green water resources: the USA, Argentina, and Brazil. As a country increases its export trade partners it tends to export relatively more blue water. However, as a country increases its import trade partners it does not preferentially import water from a specific source. The amount of virtual water that a country imports by increasing its import trade partners has been decreasing over time, with the exception of the soy trade. Both blue and green virtual water networks are efficient: 119 × 109 m3 blue and 105 × 109 m3 green water were saved in 2008. Importantly, trade has been increasingly saving water over time, due to the intensification of crop trade on more water-efficient links.

  3. Dynamics of Hydration Water in Sugars and Peptides Solutions

    SciTech Connect

    Perticaroli, Stefania; Nakanishi, Masahiro; Pashkovski, Eugene; Sokolov, Alexei P

    2013-01-01

    We analyzed solute and solvent dynamics of sugars and peptides aqueous solutions using extended epolarized light scattering (EDLS) and broadband dielectric spectroscopies (BDS). Spectra measured with both techniques reveal the same mechanism of rotational diffusion of peptides molecules. In the case of sugars, this solute reorientational relaxation can be isolated by EDLS measurements, whereas its ontribution to the dielectric spectra is almost negligible. In the presented analysis, we characterize the hydration water in terms of hydration number and retardation ratio between relaxation times of hydration and bulk water. Both techniques provide similar estimates of . The retardation imposed on the hydration water by sugars is 3.3 1.3 and involves only water molecules hydrogen-bonded (HB) to solutes ( 3 water molecules per sugar OH-group). In contrast, polar peptides cause longer range erturbations beyond the first hydration shell, and between 2.8 and 8, increasing with the number of chemical groups engaged in HB formation. We demonstrate that chemical heterogeneity and specific HB interactions play a crucial role in hydration dynamics around polar solutes. The obtained results help to disentangle the role of excluded volume and enthalpic contributions in dynamics of hydration water at the interface with biological molecules.

  4. Socioeconomic dynamics of water quality in the Egyptian Nile

    NASA Astrophysics Data System (ADS)

    Malik, Maheen; Nisar, Zainab; Karakatsanis, Georgios

    2016-04-01

    The Nile River remains the most important source of freshwater for Egypt as it accounts for nearly all of the country's drinking and irrigation water. About 95% of the total population is accounted to live along the Banks of the Nile(1). Therefore, water quality deterioration in addition to general natural scarcity of water in the region(2) is the main driver for carrying out this study. What further aggravates this issue is the water conflict in the Blue Nile region. The study evaluates different water quality parameters and their concentrations in the Egyptian Nile; further assessing the temporal dynamics of water quality in the area with (a) the Environmental Kuznets Curve (EKC)(3) and (b) the Jevons Paradox (JP)(4) in order to identify water quality improvements or degradations using selected socioeconomic variables(5). For this purpose various environmental indicators including BOD, COD, DO, Phosphorus and TDS were plotted against different economic variables including Population, Gross Domestic Product (GDP), Annual Fresh Water Withdrawal and Improved Water Source. Mathematically, this was expressed by 2nd and 3rd degree polynomial regressions generating the EKC and JP respectively. The basic goal of the regression analysis is to model and highlight the dynamic trend of water quality indicators in relation to their established permissible limits, which will allow the identification of optimal future water quality policies. The results clearly indicate that the dependency of water quality indicators on socioeconomic variables differs for every indicator; while COD was above the permissible limits in all the cases despite of its decreasing trend in each case, BOD and phosphate signified increasing concentrations for the future, if they continue to follow the present trend. This could be an indication of rebound effect explained by the Jevons Paradox i.e. water quality deterioration after its improvement, either due to increase of population or intensification

  5. Dynamic water accounting in heavily committed river basins

    NASA Astrophysics Data System (ADS)

    Tilmant, Amaury; Marques, Guilherme

    2014-05-01

    Many river basins throughout the world are increasingly under pressure as water demands keep rising due to population growth, industrialization, urbanization and rising living standards. In the past, the typical answer to meet those demands focused on the supply-side and involved the construction of hydraulic infrastructures to capture more water from surface water bodies and from aquifers. As river basins were being more and more developed, downstream water users and ecosystems have become increasingly dependant on the management actions taken by upstream users. The increased interconnectedness between water users, aquatic ecosystems and the built environment is further compounded by climate change and its impact on the water cycle. Those pressures mean that it has become increasingly important to measure and account for changes in water fluxes and their corresponding economic value as they progress throughout the river system. Such basin water accounting should provide policy makers with important information regarding the relative contribution of each water user, infrastructure and management decision to the overall economic value of the river basin. This paper presents a dynamic water accounting approach whereby the entire river basin is considered as a value chain with multiple services including production and storage. Water users and reservoirs operators are considered as economic agents who can exchange water with their hydraulic neighbors at a price corresponding to the marginal value of water. Effective water accounting is made possible by keeping track of all water fluxes and their corresponding transactions using the results of a hydro-economic model. The proposed approach is illustrated with the Eastern Nile River basin in Africa.

  6. Dynamics of Biofilm Regrowth in Drinking Water Distribution Systems

    PubMed Central

    Husband, S.; Loza, V.; Boxall, J.

    2016-01-01

    ABSTRACT The majority of biomass within water distribution systems is in the form of attached biofilm. This is known to be central to drinking water quality degradation following treatment, yet little understanding of the dynamics of these highly heterogeneous communities exists. This paper presents original information on such dynamics, with findings demonstrating patterns of material accumulation, seasonality, and influential factors. Rigorous flushing operations repeated over a 1-year period on an operational chlorinated system in the United Kingdom are presented here. Intensive monitoring and sampling were undertaken, including time-series turbidity and detailed microbial analysis using 16S rRNA Illumina MiSeq sequencing. The results show that bacterial dynamics were influenced by differences in the supplied water and by the material remaining attached to the pipe wall following flushing. Turbidity, metals, and phosphate were the main factors correlated with the distribution of bacteria in the samples. Coupled with the lack of inhibition of biofilm development due to residual chlorine, this suggests that limiting inorganic nutrients, rather than organic carbon, might be a viable component in treatment strategies to manage biofilms. The research also showed that repeat flushing exerted beneficial selective pressure, giving another reason for flushing being a viable advantageous biofilm management option. This work advances our understanding of microbiological processes in drinking water distribution systems and helps inform strategies to optimize asset performance. IMPORTANCE This research provides novel information regarding the dynamics of biofilm formation in real drinking water distribution systems made of different materials. This new knowledge on microbiological process in water supply systems can be used to optimize the performance of the distribution network and to guarantee safe and good-quality drinking water to consumers. PMID:27208119

  7. WATER TEMPERATURE DYNAMICS IN EXPERIMENTAL FIELD CHANNELS: ANALYSIS AND MODELING

    EPA Science Inventory

    This study is on water temperature dynamics in the shallow field channels of the USEPA Monticello Ecological Research Station (MERS). The hydraulic and temperature environment in the MERS channels was measured and simulated to provide some background for several biological studie...

  8. Static and dynamic properties of supercooled water in small nanotubes.

    PubMed

    Khademi, Mahdi; Sahimi, Muhammad

    2016-07-14

    The static and dynamic properties of water in small silicon-carbide and carbon nanotubes have been studied over the temperature range 100 K-298 K, using extensive molecular dynamics simulations. The computed properties include the radial distribution function, the cage correlation function, the space-time autocorrelation function, the velocity autocorrelation function, and the self-diffusivity. They all indicate that, under the conditions that we study, water does not freeze in small nanotubes; the Stokes-Einstein relation breaks down, and the self-diffusivity exhibits a transition around 230 K, very close to 228 K, the temperature at which a fragile-to-strong dynamic crossover is supposed to happen. The cage correlation function C(t) decays according to a stretched-exponential function, C(t) ∼ exp[ - (t/τ)(β)], where τ is a relaxation time and β is a topological exponent. PMID:27421415

  9. Static and dynamic properties of supercooled water in small nanotubes

    NASA Astrophysics Data System (ADS)

    Khademi, Mahdi; Sahimi, Muhammad

    2016-07-01

    The static and dynamic properties of water in small silicon-carbide and carbon nanotubes have been studied over the temperature range 100 K-298 K, using extensive molecular dynamics simulations. The computed properties include the radial distribution function, the cage correlation function, the space-time autocorrelation function, the velocity autocorrelation function, and the self-diffusivity. They all indicate that, under the conditions that we study, water does not freeze in small nanotubes; the Stokes-Einstein relation breaks down, and the self-diffusivity exhibits a transition around 230 K, very close to 228 K, the temperature at which a fragile-to-strong dynamic crossover is supposed to happen. The cage correlation function C(t) decays according to a stretched-exponential function, C(t) ˜ exp[ - (t/τ)β], where τ is a relaxation time and β is a topological exponent.

  10. Isotopic geochemistry and cosmochemistry

    NASA Astrophysics Data System (ADS)

    Shchukoliukov, Iu. A.

    The book includes recent information on isotope geology, geochemistry, and cosmochemistry, discussed at a recent Soviet-Japanese symposium (at Irkutsk, USSR). Attention is given to numerical modeling of geochronometric systems, a classification of noble-gas components in the earth's interior, the feasibility of using ion microprobe for local isotope analysis of zircons for the purpose of deriving the early history of the earth (on the example of the Novopavlovsk complex from the Ukranian shield), a geological and geochronological study of the Ganalski complex of Kamchatka, and strontium isotopes as a criterion of the nature of acid melts (i.e., mantle- or crust-related). Other papers are on the geochronology and geology of Siberian kimberlites, the nature of sulfur from effusive rocks of the Kamchatka-Kuril-Japan island arc, mass-spectrometric studies of volatile components in exocontact rocks of alkaline-basic intrusions, and an analytical method for stable-isotope analysis in ultrasmall amounts of CO2 and its application to studies of the microscale isotopic zoning in calcite and graphite crystals in marble.