Microbial communities and transformation of carbon compounds in bog soils of the taiga zone (Tomsk oblast)

NASA Astrophysics Data System (ADS)

Grodnitskaya, I. D.; Trusova, M. Yu.

2009-09-01

Two types of bogs were studied in Tomsk oblast—Maloe Zhukovskoe (an eutrophic peat low-moor bog) and Ozernoe (an oligotrophic peat high-moor bog). The gram-negative forms of Proteobacteria were found to be dominant and amounted to more than 40% of the total population of the microorganisms investigated. In the peat bogs, the population and diversity of the hydrolytic microbial complex, especially of the number of micromycetes, were lower than those in the mineral soils. The changes in the quantitative indices of the total microbiological activity of the bogs were established. The microbial biomass and the intensity of its respiration differed and were also related to the depth of the sampling. In the Zhukovskoe peat low-moor bog, the maximal biomass of heterotrophic microorganisms (154 μg of C/g of peat) was found in the aerobic zone at a depth of 0 to 10 cm. In the Ozernoe bog, the maximal biomass was determined in the zone of anaerobiosis at a depth of 300 cm (1947 μ g of C/g of peat). The molecular-genetic method was used for the determination of the spectrum of the methanogens. Seven unidentified dominant forms were revealed. The species diversity of the methanogens was higher in the oligotrophic high-moor bog than in the eutrophic low-moor bog.

National Program for Inspection of Non-Federal Dams. New Pond Dam (MA 00779), Massachusetts Coastal Basin, Easton, Massachusetts. Phase I Inspection Report.

DTIC Science & Technology

1981-07-01

formerly provided irrigation water for the Hammond-Fuller i cranberry bogs. At the present the reservoir continues to service some bogs approximately 2...there are few depressions or irregularities. Vegetation along the edges of the crest consist of short brush, scattered trees up to 22 in. diameter...dam formerly provided irrigation water for cranberry bogs downstream and continues to service some bogs although the owners of the bogs have no

Geoinformatics meets education for a peat bog information system

NASA Astrophysics Data System (ADS)

Michel, Ulrich; Fiene, Christina; Plass, Christian

2010-10-01

Within the project "Expedition Bog: Young researchers are experimenting, exploring and discovering" a bog-information- system is developed by the Department of Geography (University of Education Heidelberg, Germany), the Institute for Geoinformatics and Remote Sensing (University of Osnabrueck, Germany; the NABU Umweltpyramide gGmbH. This information system will be available for schools and to the public. It is supplemented by teaching units on various topics around the bog via an online platform. The focus of the project, however, is the original encounter with the bog habitat. This is realized by a GPS scavenger hunt with small research tasks and observations, mapping and experiments. The project areas are the Huvenhoops bog and the Lauenbruecker bog in Rotenburg in Lower Saxony, Germany. Equipped with a researcher backpack, GPS device and a mobile bog book by means of a pocket PC, students can discover different learning stations in the project bogs. In our areas the students can learn more about different topics such as "the historical memory of the bog", "water", "peat moss and other plants" and "animals of the bog". Moreover small inquiry research projects can be executed. Experimenting on site helps students to develop important scientific findings and increases their curiosity and enthusiasm for nature. It also promotes a number of other basic skills such as literacy, language skills, social skills or fine motor skills. Moreover it also fosters the development of a positive attitude to science in general. The main objective of the project is to promote sustainable environmental education, as well as the development of environmental awareness. This will be accomplished through the imparting of knowledge but also through experiencing nature with all senses in the context of original encounters.

Quantifying the Microbial Utilization of Methanogenesis and Methane Loss from Northern Wetlands

NASA Astrophysics Data System (ADS)

Corbett, J. E.; Tfaily, M.; Burdige, D.; Glaser, P. H.; Chanton, J.

2014-12-01

The importance of methanogenesis and percent of methane loss from the subsurface porewater in various northern wetland sites was quantified with isotope-mass balance equations. With equimolar amounts of CO2 and CH4 produced from methanogenesis, the amount of dissolved CO2 produced from methanogenesis as compared to other decomposition processes can be calculated and is equivalent to the amount of CH4 before loss due to ebullition, plant-mediated transport, and diffusion. This method was applied to porewater samples collected from various locations within permafrost collapse-scar bogs and northern peatlands. From the peatland sites, bogs produced less CO2-meth than fens (2.9 ± 1.3 mM and 3.7 ± 1.4 mM, respectively). Methanogenesis was a more utilized decomposition process in the bogs than the fens. However, greater amounts of CO2-meth found in fen sites was most likely due to the presence of more labile organic substrates resulting in greater overall production. More CH4 was lost in fens (89 ± 2.8%) than bogs (82 ± 5.3%) from plant-mediated transport as fens are dominated by vascular plants (Carex) while bogs are dominated by Sphagnum mosses. In permafrost sites, mid-bogs produced twice the amount of CO2-meth as bog moats (1.6 ± 0.63 mM and 0.82 ± 0.20 mM, respectively). Less methanogenesis was found in bog moats as recently thawed organic matter is exposed to initial decomposition processes and methane production grows over time. A similar amount of CH4 was lost from bog moats as mid bogs (63 ± 7.0% and 64 ± 9.3%, respectively) likely due to the greater density of vascular plants found within a bog moat.

Rain increases methane production and methane oxidation in a boreal thermokarst bog

NASA Astrophysics Data System (ADS)

Neumann, R. B.; Moorberg, C.; Turner, J.; Wong, A.; Waldrop, M. P.; Euskirchen, E. S.; Edgar, C.; Turetsky, M. R.

2017-12-01

Bottom-up biogeochemical models of wetland methane emissions simulate the response of methane production, oxidation and transport to wetland conditions and environmental forcings. One reason for mismatches between bottom-up and top-down estimates of emissions is incomplete knowledge of factors and processes that control microbial rates and methane transport. To advance mechanistic understanding of wetland methane emissions, we conducted a multi-year field investigation and plant manipulation experiment in a thermokarst bog located near Fairbanks, Alaska. The edge of the bog is experiencing active permafrost thaw, while the center of the bog thawed 50 to 100 years ago. Our study, which captured both an average year and two of the wettest years on record, revealed how rain interacts with vascular vegetation and recently thawed permafrost to affect methane emissions. In the floating bog, rain water warmed and oxygenated the subsurface, but did not alter soil saturation. The warmer peat temperatures increased both microbial methane production and plant productivity at the edge of the bog near the actively thawing margin, but minimally altered microbial and plant activity in the center of the bog. These responses indicate processes at the edge of the bog were temperature limited while those in the center were not. The compounding effect of increased microbial activity and plant productivity at the edge of the bog doubled methane emissions from treatments with vascular vegetation during rainy years. In contrast, methane emissions from vegetated treatments in the center of the bog did not change with rain. The oxygenating influence of rain facilitated greater methane oxidation in treatments without vascular vegetation, which offset warming-induced increases in methane production at the edge of the bog and decreased methane emissions in the center of the bog. These results elucidate the complex and spatially variable response of methane production and oxidation in thermokarst bogs to energy and oxygen inputs from rain, and have implications for how boreal wetland methane emissions may respond in the future to altered precipitation patterns. Advective delivery of energy and oxygen to wetland subsoils via rainwater is not currently a mechanism included in bottom-up wetland methane models.

Comparisons of soil nitrogen mass balances for an ombrotrophic bog and a minerotrophic fen in northern Minnesota

EPA Science Inventory

We compared the N budgets of an ombrotrophic bog and a minerotrophic fen to quantify the importance of denitrification in peatlands and their watersheds. We also compared the watershed upland mineral soils to bog/fen peat; lagg and transition zone peat to central bog/fen peat; an...

Formation of lacustrine plains in west-central Alaska as a result of permafrost degradation and aggradation

NASA Astrophysics Data System (ADS)

Kanevskiy, M. Z.; Jorgenson, M. T.; Shur, Y.; O'Donnell, J.; Harden, J. W.; Fortier, D.

2012-12-01

Perennially frozen lacustrine sediments containing a large amount of ground ice comprise a significant part of the upper permafrost of the lowlands of west-central Alaska, including Koyukuk Flats and Innoko Flats. Study sites are located in the discontinuous permafrost zone, where permafrost was encountered mainly within uplifted peat plateaus. The upper part of studied sections is formed by frozen peat up to 3 m thick underlain by lacustrine silt, which is mostly ice-rich. Cryogenic structure of lacustrine sediments at different sites has common features: (1) prevalence of layered, braided, and reticulate cryostructures; (2) high variability in the ice content of sediments; (3) high density and low water content of soil aggregates separated by ice lenses. Volume of visible ice in silt reaches at places 40% and more. The thickness of ice lenses generally varies from 1 to 5 cm and occasionally reaches 10 cm. Remnants of peat plateaus are surrounded by unfrozen bogs and fens, formed as a result of thawing and settling of ice-rich lacustrine silt. Modern thermokarst scars initially form at places where ice-rich silt is not protected by a thick layer of organic material. Further development of thermokarst bogs includes lateral enlargement of thaw bulbs and collapsing of the margins of peat plateaus. Lacustrine silt within taliks is covered by woody peat accumulated under forests during the stage of permafrost plateau formation and then by aquatic sphagnum peat accumulated in taliks after collapse. We relate the formation of ice-rich lacustrine sediments to development of lake thermokarst, which affected ice-rich silty yedoma deposits during the transition from Pleistocene to Holocene. Terrain development in lacustrine lowlands of west-central Alaska includes five stages related to permafrost aggradation and degradation from the late Pleistocene to the present time: 1) formation of the ice-rich syngenetic permafrost (yedoma) during the late Pleistocene; 2) yedoma degradation in the yearly Holocene and formation of thaw lakes; 3) complete yedoma degradation under thaw lakes and refreezing of thawed sediments at elevated areas; 4) peat accumulation and freezing of sediments in thaw lake basins; and 5) new cycle of thermokarst and formation of taliks under thaw lakes, bogs and fens. Stages of terrain development of lacustrine lowlands since the Late Pleistocene

SPRUCE S1 Bog Fine-root Production and Standing Crop Assessed With Minirhizotrons in the Southern and Northern Ends of the S1 Bog

DOE Data Explorer

Iversen, C. M. [Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA; Childs, J. [Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA; Norby, R. J. [Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA; Garrett, A. [Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA; Martin, A. [Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA; Spence, J. [Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA; Ontl, T. A. [Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA

2017-01-01

This data set reports fine-root peak growth and standing crop measurements from a forested, ombrotrophic bog as determined using non-destructive minirhizotron technology. Minirhizotron images were collected throughout the growing seasons of 2011 and 2012 at the southern and northern ends of the S1 bog across gradients of tree density in paired hummock and hollow microtopography. The dominant woody species in the bog, and focus of the investigation, were trees Picea mariana and Larix laricina, and ericaceous shrubs Rhododendron groenlandicum and Chamaedaphne calyculata.

Dynamic Vertical Profiles of Peat Porewater Chemistry in a Northern Peatland

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

Griffiths, Natalie A.; Sebestyen, Stephen D.

We measured pH, cations, nutrients, and total organic carbon (TOC) over 3 years to examine weekly to monthly variability in porewater chemistry depth profiles (0–3.0 m) in an ombrotrophic bog in Minnesota, USA. We also compared temporal variation at one location to spatial variation in depth profiles at 16 locations across the bog. Most solutes exhibited large gradients with depth. pH increased by two units and calcium concentrations increased over 20 fold with depth, and may reflect peatland development from minerotrophic to ombrotrophic conditions. Ammonium concentrations increased almost 20 fold and TOC concentrations decreased by half with depth, and thesemore » patterns likely reflect mineralization of peat or decomposition of TOC. There was also considerable temporal variation in the porewater chemistry depth profiles. Ammonium, soluble reactive phosphorus, and potassium showed greater temporal variation in near-surface porewater, while pH, calcium, and TOC varied more at depth. This variation demonstrates that deep peat porewater chemistry is not static. Lastly, temporal variation in solute chemistry depth profiles was greater than spatial variation in several instances, especially in shallow porewaters. In conclusion, characterizing both temporal and spatial variability is necessary to ensure representative sampling in peatlands, especially when calculating solute pools and fluxes and parameterizing process-based models.« less

Dynamic Vertical Profiles of Peat Porewater Chemistry in a Northern Peatland

DOE PAGES

Griffiths, Natalie A.; Sebestyen, Stephen D.

2016-10-14

We measured pH, cations, nutrients, and total organic carbon (TOC) over 3 years to examine weekly to monthly variability in porewater chemistry depth profiles (0–3.0 m) in an ombrotrophic bog in Minnesota, USA. We also compared temporal variation at one location to spatial variation in depth profiles at 16 locations across the bog. Most solutes exhibited large gradients with depth. pH increased by two units and calcium concentrations increased over 20 fold with depth, and may reflect peatland development from minerotrophic to ombrotrophic conditions. Ammonium concentrations increased almost 20 fold and TOC concentrations decreased by half with depth, and thesemore » patterns likely reflect mineralization of peat or decomposition of TOC. There was also considerable temporal variation in the porewater chemistry depth profiles. Ammonium, soluble reactive phosphorus, and potassium showed greater temporal variation in near-surface porewater, while pH, calcium, and TOC varied more at depth. This variation demonstrates that deep peat porewater chemistry is not static. Lastly, temporal variation in solute chemistry depth profiles was greater than spatial variation in several instances, especially in shallow porewaters. In conclusion, characterizing both temporal and spatial variability is necessary to ensure representative sampling in peatlands, especially when calculating solute pools and fluxes and parameterizing process-based models.« less

Comparisons of soil nitrogen mass balances for an ...

EPA Pesticide Factsheets

We compared the N budgets of an ombrotrophic bog and a minerotrophic fen to quantify the importance of denitrification in peatlands and their watersheds. We also compared the watershed upland mineral soils to bog/fen peat; lagg and transition zone peat to central bog/fen peat; and surface, mid-layer and deep soil and peat horizons. Bog and fen area were derived from a wetland boundary GIS data layer, and bog and fen volumes were calculated as the interpolated product of area and depth of peat. Atmospheric N deposition to the bog and fen were based on measurements from a station located 2km north of the bog watershed and 0.5km from the fen watershed. Precipitation was analyzed for nitrate (NO3-), ammonium (NH4+), and total N (TN), and aggregated to annual values. Outflow water samples from the bog and fen were collected as surface grab samples on each of the May-October sampling dates over the 2010-2013 study, and were analyzed and aggregated annually as for atmospheric N. Soil and peat samples were analyzed for N content, and for net ammonification (AM), nitrification (NT), and ambient (DN) and potential (DEA) denitrification rates. Nitrogen mass balances are based on mean annual atmospheric deposition and outflow; soil and peat standing stocks of N, and mean annual estimates of DN, weighted for contributions of the uplands, lagg or transition zone, and bog or fen hollows and hummocks, and accounting for soil depth effects. Annual deposition of N species was: N

Biogeochemistry of aquatic humic substances in Thoreau's Bog, Concord, Massachusetts

USGS Publications Warehouse

McKnight, Diane M.; Thurman, E. Michael; Wershaw, Robert L.; Hemond, Herold

1985-01-01

Thoreau's Bog is an ombrotrophic floating—mat Sphagnum bog developed in a glacial kettlehole and surrounded by a red maple swamp. Concentrations of dissolved organic carbon in the porewater of the bog average 36 mg/L and are greatest near the surface, especially during late summer. This distribution suggest that the upper layer of living and dead Sphagnum and moderately humified peat is the major site of dissolved organic material production in the bog. The dissolved organic material consists mainly of aquatic fulvic acid (67%) and hydrophilic acids (20%); these organic acids control the pH (typically 4 or somewhat lower) of the bogwater. The elemental, amino acid, carbohydrate, and carboxylic acid contents of fulvic acid from the bog are similar to those of aquatic fulvic acid from the nearby Shawsheen River, although the phenolic hydroxyl content of fulvic acid from Thoreau's Bog is higher. The hydrophilic acids have greater amino acid, carbohydrate, and carboxylic acid contents than the fulvic acid, consistent with the hypothesis that hydrophilic acids are more labile intermediate compounds in the formation of fulvic acid.

Anthropogenic degradation of mountainous raised bogs. Case study of the Polish Carpathians

NASA Astrophysics Data System (ADS)

Lajczak, Adam

2016-04-01

Publications on the human impact on peat bogs pay a lot of attention to peat erosion, peat burning and changes in the physical and chemical properties of peat deposits that indicate pollution in the environment, but a more detailed analysis of current changes in the peat bog relief as a result of peat deposit extraction and drying is omitted. Compared to other areas of the world, the level of knowledge on anthropogenic changes in the relief of peat bogs in some areas of Poland may be considered advanced. This applies not only to peat bogs in northern Poland but also southern Poland, where peat bogs in the Carpathians and the Sudetes are also found. The best analyzed peat bogs in southern Poland are the raised bogs in the Orawsko-Nowotarska Basin (Western Carpathians) and in valleys in the Bieszczady Mts. (Eastern Carpathians). Both areas are impacted by deep precipitation shadow. The purpose of this paper is: (1) to assess the rate of shrinkage in the surface area of peat domes in the mentioned areas, (2) to describe the rate of growth in the surface area of older and younger post-peat areas, (3) to explain current changes in peat bogs morphology, (4) to explain changes in water retention in peat deposit, (5) to separate phases in peat bogs relief changes. With that in mind, the direction and rate of change of landforms typical of younger post-peat areas, such as peat extraction scarps, post-extraction hollows, drainage systems including ditches and regulated stream channels, were analyzed. A special emphasis was placed on the period of time when the restoration of such areas has taken place. The paper is based on an analysis of maps produced over the last 230 years as well as on aerial photographs taken since 1965 and on LiDAR data. Fieldwork included the geomorphological and hydrographic mapping of specified landforms within peat bogs using GPS methods. In period prior to human activity peat domes were larger than today and were surrounded by lagg fens and were drained by meandering streams. In period prior to the end of peat extraction and drying the amount of area lost by the peat dome and former wetland fringe can be identified in terms of older and younger post-peat areas. Stream channels in the general area have been regulated and drainage ditches dug. Partial or full peat extraction taking place primarily in the domes' fringe zone has produced major changes in peat bog relief and has substantially reduced peat bog water content. The increased density of drainage ditches in the area surrounding the remnants of peat domes has led to further drying of the peat bogs. An unintended consequence of stream regulation are shallower and wider channels that evolve into braided channels with a local tendency to aggradate material. The current stage of peat bogs development is their restoration which started when peat extraction had been halted in most peat bogs and drainage ditch maintenance had been abandoned.

Investigating Bogs: An Interdisciplinary Adventure.

ERIC Educational Resources Information Center

Pankiewicz, Philip R.; Schneider, Lois

1995-01-01

Presents the case for the use of bogs as ideal sites for hundreds of interdisciplinary lessons that combine chemistry, geology, various branches of biology, and wetlands archaeology. Includes general guidelines to aid in the design of interdisciplinary bog studies. (DDR)

Correlation between the morphogenetic types of litter and their properties in bog birch forests

NASA Astrophysics Data System (ADS)

Efremova, T. T.; Efremov, S. P.; Avrova, A. F.

2010-08-01

A formalized arrangement of morphogenetic types of litter according to the physicochemical parameters provided their significant grouping in three genetic associations. The litter group (highly decomposed + moderately decomposed) is confined to the tall-grass group of bog birch forests. The rhizomatous (roughly decomposed) litter is formed in the sedge-reed grass bog birch forests. The litter group (peaty + peatified + peat) is associated with the bog-herbaceous-moss group of forest types. The genetic associations of the litters (a) reliably characterize the edaphic conditions of bog birch forests and (b)correspond to formation of the peat of certain ecological groups. We found highly informative the acid-base parameters, the exchangeable cations (Ca2+ + Mg2+) and the total potential acidity, which differentiated the genetic associations of litter practically with 100% probability. The expediency of studying litters under groups of forest types rather than under separate types of bog birch forests was demonstrated.

Evidence for latest Pleistocene to Holocene uplift at the southern margin of the Central Anatolian Plateau (CAP), southern Turkey

NASA Astrophysics Data System (ADS)

Cosentino, Domenico; Öǧretmen, Nazik; Cipollari, Paola; Gliozzi, Elsa; Radeff, Giuditta; Yıldırım, Cengiz; Baykara, Oruc M.; Shen, Chuan-Chou

2016-04-01

Along the Mediterranean coastal area of southern Anatolia, markers of ancient sea-level have been reported west of Alanya and east of the Göksu delta. In both areas, bioconstructed fossil rims, consisting mainly of calcareous algae, are situated 0.5 m above the live counterpart. The fossil rim to the west of Alanya has been dated between 2690 to 1545 yrs BP, evidencing late Holocene rock uplift at the CAP southern margin. More recently, based on beachrocks along the coastal area from Incekum to the south of Adana, authors showed that the shoreline was raised around 0.5 m after 19 BC-200 AD. Based on new field observations along the coast between Aydı ncı k and Ayaş (Mersin, southern Turkey), together with AMS 14C dating and high-resolution U-Th chronology, a more complex uplift history can be suggested. Along the coast of Yeşilovacı k, we observed up to seven uplifted marine notches, from 0.5 m to 6.10 m above sea level. Some of them show relationships with a travertine crust that yielded U-Th ages of 2727 ± 1559 years and 5236 ± 2255 years. In the same area, a calcareous algae fossil trottoir related to a marine notch 5.40 m above sea level yielded an AMS 14C 2σ age of 32700 to 31645 years cal BP. Considering that the global ocean was 60 m below the present sea level at 32 ka, the Yeşilovacı k coastal area has been uplifted at 2 mm/yr. Moving to the east, in a small embayment at Eǧribük, two distinct well cemented beach deposits containing Murex brandaris, Cerithium vulgatum, and Columbella rustica have been uplifted at 0.3 m and 0.7 m above the present sea level. Although it is difficult to reconstruct the paleodepth of those beach deposits, AMS 14C 2σ ages of 5575 to 5445 years cal BP and 2130 to 1965 years cal BP show late Holocene uplift. In the Narlı kuyu area, up to seven different uplifted markers of sea level were observed between 0.8 and 7.2 m above the present sea level. In addition, near Ayaş new insights for late Holocene uplift are from the northern harbour of the ancient Roman town Elaiussa-Sebaste, which now is 4 m above sea level. More evidence for late Holocene uplift of the Elaiussa-Sebaste area come from a Roman pool located in the small peninsula to the east of the northern harbour. There, a fossil shell of Patella cf. aspera, collected 1 m above the highest living Patella, yielded an AMS 14C 2σ age of 850 to 1164 years cal AD. Considering an age of 1000 yrs AD and the level of the Mediterranean sea that was 0.2 m below the present sea level, we can estimate a tectonic uplift rate of 1.2 mm/yr for the last 1000 years. Although the CAP southern margin shows clear evidence of recent uplift, with uplift rates between 2 mm/yr to 1.2 mm/yr, to reconstruct a well-constrained uplift curve for the Holocene more AMS 14C and U-Th dates need to be collected.

Impact of raized bogs on export of carbon and river water chemical composition in Western Siberia

NASA Astrophysics Data System (ADS)

Voistinova, Elena

2010-05-01

Bogs play an important role in functioning of the biosphere. Specific geochemical environment of the bogs results in formation of the special biogeochemical cycle of the elements. Processes of decay and transformation of organic material define the reductive conditions of bog water, form and migratory mobility of the chemical elements. Particular interest in recent years is aroused by the question of content and dynamics of the carbon in bog and river water according to indicated natural and climatic changes on the territory. The most important parts of the carbon balance in bog ecosystems together with processes of exhalation from deposit surface in the form of CO2 is its export with river water. The results of research carried out in scientific station "Vasyugansky" in south taiga subzone of Western Siberia showed that chemical composition of raised bog water includes high amounts of total iron (2,13 mg/l), ammonium ions (5,33 mg/l), humic and fulvic acids (5,21 mg/l and 45,8 mg/l), dissolved organic carbon (69,1 mg/l), COD (236,93 mgO/l), there are low mineralization and indicators of pH. Carbon comes in bog water in organic compounds: carboxylic acids, phenols, aromatic and paraffin hydrocarbons, organic phosphates, phthalates and other compounds. Formation of river waters composition in the Western Siberia takes place in the following context: high level of bogged river catchments (sometimes up to 70%), excess humidification and low heat provision. Basing on the results of study of hydrochemical runoff in small and medium rivers with different levels of bogged in river catchments (Chaya, Bakchar, Klyuch, Gavrilovka) it was noted that raised bog influence on river waters chemical composition shows in ion runoff decrease, organic substances runoff increase, increase of amounts of total iron, ammonium irons and water pH indicators decrease. Study of humic matters migration is very important in the context of formation of flexible complexes of humic and fulvic acids and heavy metals, which should be taken into account when in waterlogged regions constructing large industrial projects and in formation of water removing.

Effects of environmental and anthropogenic determinants on changes in groundwater levels in selected peat bogs of Slowinski National Park, northern Poland

NASA Astrophysics Data System (ADS)

Chlost, Izabela; Cieśliński, Roman

2018-03-01

The present study focuses on two Baltic-type peat bogs in Slowinski National Park, namely that at Żarnowskie and at Kluki, located in the Lake Łebsko catchment and both characterised by a centrally located dome with a very marshy fringe area featuring an emerging marshy coniferous forest (Vaccinio uliginosi-Pinetum). The Żarnowskie bog is under active protection. A total of 24 flow barriers were installed in drainage ditches during the years 2006 and 2007. The purpose of these barriers was to put a halt to water outflow. In addition, 30 hectares of young pine forest were cleared in order to decrease loss of water via evapotranspiration. Kluki peat bog is only partially protected by Polish law. The lack of efforts to prevent outflow via the canal is due to the fact that the canal is utilised to drain meadows in the vicinity of the village of Łokciowe outside of the national park. Peat formation no longer occurs in this peat bog. The hydrological condition of the bog is catastrophic as a result of its main canal, referred to as Canal C9, which is 2.5 to 3.0 m deep and 10 m wide in places. Both peat bogs are monitored for fluctuations in groundwater. Research has shown that changes in water levels fluctuate based on season of the year and geographical location, which is illustrated quite well using the two studied peat bogs. The water retention rate of the Żarnowskie peat bog may be considered fairly high and is likely to improve due to protective measures enabled by Polish environmental laws. The water retention rate of the bog is consistently improving thanks to these measures, fluctuations in water level are small and the water level does not drop under 0.5 m below ground level even under extreme hydrometeorological conditions. This yields optimum conditions for renewed peat formation in this area. One potential threat is the Krakulice peat extraction facility, which is located in the southern part of the bog close to the boundary with the national park.

SPRUCE S1 Bog and SPRUCE Experiment Location Survey Results, 2015

DOE Data Explorer

Griffiths, Natalie A. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; Hook, L. A. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; Hanson, P. J. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.

2016-01-01

This data set provides a record of the horizontal and vertical survey results of SPRUCE experimental infrastructure and measurement locations on the S1-Bog on the Marcell Experimental Forest and the SPRUCE experimental site within the S1-Bog.

SPRUCE S1 Bog Vegetation Survey and Peat Depth Data: 2009

DOE Data Explorer

Hanson, P. J. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A

2009-12-31

This data set reports the results of a field survey of the S1 Bog to characterize the vegetation and to determine peat depth. The survey was conducted on September 21 and 22, 2009. The initial survey of vegetation and peat depth characteristics of the target bog was conducted to evaluate the logical locations for installing replicated experimental blocks for SPRUCE. The goal was to identify multiple locations of uniform aboveground vegetation and belowground peat depth for positioning experimental units within the bog.

Bog iron formation in the Nassawango Creek watershed, Maryland, USA

USGS Publications Warehouse

Bricker, O.P.; Newell, Wayne L.; Simon, N.S.; ,

2004-01-01

The Nassawango bog ores in the modern environment for surficial geochemical processes were studied. The formation of Nassawango bog ores was suggested to be due to inorganic oxidation when groundwater rich in ferrous iron emerges into the oxic, surficial environment. It was suggested that the process, providing a phosphorus sink, may be an unrecognized benefit for mitigating nutrient loading from agricultural lands. It is found that without the effect of iron fixing bacteria, bog deposites could not form at significant rates.

Paired charcoal and tree-ring records of high-frequency Holocene fire from two New Mexico bog sites

USGS Publications Warehouse

Allen, Craig D.; Anderson, R. Scott; Jass, R.B.; Toney, J.L.; Baisan, C.H.

2008-01-01

Two primary methods for reconstructing paleofire occurrence include dendrochronological dating of fire scars and stand ages from live or dead trees (extending back centuries into the past) and sedimentary records of charcoal particles from lakes and bogs, providing perspectives on fire history that can extend back for many thousands of years. Studies using both proxies have become more common in regions where lakes are present and fire frequencies are low, but are rare where high-frequency surface fires dominate and sedimentary deposits are primarily bogs and wetlands. Here we investigate sedimentary and fire-scar records of fire in two small watersheds in northern New Mexico, in settings recently characterised by relatively high-frequency fire where bogs and wetlands (Chihuahuen??os Bog and Alamo Bog) are more common than lakes. Our research demonstrates that: (1) essential features of the sedimentary charcoal record can be reproduced between multiple cores within a bog deposit; (2) evidence from both fire-scarred trees and charcoal deposits documents an anomalous lack of fire since ???1900, compared with the remainder of the Holocene; (3) sedimentary charcoal records probably underestimate the recurrence of fire events at these high-frequency fire sites; and (4) the sedimentary records from these bogs are complicated by factors such as burning and oxidation of these organic deposits, diversity of vegetation patterns within watersheds, and potential bioturbation by ungulates. We consider a suite of particular challenges in developing and interpreting fire histories from bog and wetland settings in the Southwest. The identification of these issues and constraints with interpretation of sedimentary charcoal fire records does not diminish their essential utility in assessing millennial-scale patterns of fire activity in this dry part of North America. ?? IAWF 2008.

Functional diversity, succession, and human-mediated disturbances in raised bog vegetation.

PubMed

Dyderski, Marcin K; Czapiewska, Natalia; Zajdler, Mateusz; Tyborski, Jarosław; Jagodziński, Andrzej M

2016-08-15

Raised and transitional bogs are one of the most threatened types of ecosystem, due to high specialisation of biota, associated with adaptations to severe environmental conditions. The aim of the study was to characterize the relationships between functional diversity (reflecting ecosystem-shaping processes) of raised bog plant communities and successional gradients (expressed as tree dimensions) and to show how impacts of former clear cuts may alter these relationships in two raised bogs in 'Bory Tucholskie' National Park (N Poland). Herbaceous layers of the plant communities were examined by floristic relevés (25m(2)) on systematically established transects. We also assessed patterns of tree ring widths. There were no relationships between vegetation functional diversity components and successional progress: only functional dispersion was negatively, but weakly, correlated with median DBH. Lack of these relationships may be connected with lack of prevalence of habitat filtering and low level of competition over all the successional phases. Former clear cuts, indicated by peaks of tree ring width, influenced the growth of trees in the bogs studied. In the bog with more intensive clear cuts we found more species with higher trophic requirements, which may indicate nutrient influx. However, we did not observe differences in vegetation patterns, functional traits or functional diversity indices between the two bogs studied. We also did not find an influence of clear cut intensity on relationships between functional diversity indices and successional progress. Thus, we found that alteration of the ecosystems studied by neighbourhood clear cuts did not affect the bogs strongly, as the vegetation was resilient to these impacts. Knowledge of vegetation resilience after clear cuts may be crucial for conservation planning in raised bog ecosystems. Copyright © 2016 Elsevier B.V. All rights reserved.

Pb inventory in an ombrotrophic bog decreases over time

NASA Astrophysics Data System (ADS)

Baumann, E.; Jeremiason, J.; Sebestyen, S.

2016-12-01

Peat cores were collected from the S2 ombrotrophic bog at the Marcell Experimental Forest (MEF) to determine if the Pb inventory in the bog has decreased over time. Pb concentrations in the outflow of the bog measured from 2009-2016 indicated continued mobilization and export of Pb out of the bog despite dramatic decreases in atmospheric deposition. A seminal study conducted by Urban et al. (1990) from 1981-1983 calculated a mass balance of Pb in the S2 watershed which included a Pb inventory in peat based on the approximate time frame of 1930 to 1983. We collected peat cores in 2016 to compare peat inventories of Pb over the same time range. We found that Pb inventories in the peat have decreased over time, consistent with Pb being mobilized by dissolved organic carbon (DOC) and gradually flushed out of the bog. Since 1983, DOC levels may have increased leading to further Pb mobilization and transport from the bog, but this trend is unclear. In contrast to Pb concentrations in the outflow water, upland runoff and the surface sphagnum moss layer have dramatically lower Pb concentrations compared to 1980s levels indicating fast ecosystem responses to a decrease in Pb inputs in these compartments. However, the deeper peat layers near the water table are responding more slowly to the decrease in Pb inputs and historical Pb inputs continue to be mobilized and transported from the bog. Our results would be applicable to other trace metals, such as Hg, that bind strongly to DOC. For example, a dramatic decrease in Hg deposition would not result in near-term decreases in Hg out of the bog.

Late Holocene palaeoclimate variability: The significance of bog pine dendrochronology related to peat stratigraphy. The Puścizna Wielka raised bog case study (Orawa - Nowy Targ Basin, Polish Inner Carpathians)

NASA Astrophysics Data System (ADS)

Krąpiec, Marek; Margielewski, Włodzimierz; Korzeń, Katarzyna; Szychowska-Krąpiec, Elżbieta; Nalepka, Dorota; Łajczak, Adam

2016-09-01

The results of dendrochronological and palynological analyses of subfossil pine trees occurring in the peat deposits of the Puścizna Wielka raised bog (Polish Carpathians, Southern Poland) - the only site with numerous subfossil pine trees in the mountainous regions of Central Europe presently known - indicate that the majority of the tree populations grew in the peat bog during the periods ca 5415-3940 cal BP and 3050-2560 cal BP. Several forestless episodes, dated to 5245-5155 cal BP, 4525-4395 cal BP and 3940-3050 cal BP, were preceded by tree dying-off phases caused by an extreme periodical increase in humidity and general climate cooling trends. These events are documented based on analyses of pollen and non-pollen palynomorph assemblages, dendrochronological analyses of the trees, as well as numerous radiocarbon datings of the sediment horizons occurring within the peat bog profile. The phases of germinations, and, in turn, of tree and shrub invasions of the peat bog areas have been closely connected to drying and occasional warming of the regional climate. The last of the forestless periods began about 2600 years ago and continued up to the very recent times. Currently, as a result of desiccation of the peat bog and the lowering of the groundwater level (due to improved water drainage system), pine trees have returned the peat bog again. These results demonstrate that studies of subfossil bog-pine trees are quite effective in documenting and reconstructing periods of humidity fluctuation that occurred within the Carpathian region over the last several millennia.

SPRUCE S1 Bog Porewater, Groundwater, and Stream Chemistry Data: 2011-2013

DOE Data Explorer

Griffiths, N. A. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; Sebestyen, S. D. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.

2016-01-01

This data set reports the chemistry of S1 Bog porewater, outlet stream water, and groundwater from upland wells from 2011 through 2013. These data provide information for studies of the biogeochemical status of the bog and surrounding groundwater aquifer.

Community analysis of pitcher plant bogs of the Little River Canyon National Preserve, Alabama

Treesearch

Robert Carter; Terry Boyer; Heather McCoy; Andrew J. Londo

2006-01-01

Pitcher plant bogs of the Little River Canyon National Preserve in northern Alabama contain the federally endangered green pitcher plant [Sarracenia oreophila (Kearney) Wherry]. Multivariate analysis of the bog vegetation and environmental variables revealed three communities with unique species compositions and soil characteristics. The significant...

EVALUATING CUMULATIVE EFFECTS OF DISTURBANCE ON THE HYDROLOGIC FUNCTION OF BOGS, FENS, AND MIRES

EPA Science Inventory

Few quantitative studies have been done on the hydrology of fens, bogs and mires, and consequently any predictions of the cumulative impacts of disturbances on their hydrologic functions is extremely difficult. or example, few data are available on the role of bogs and fens with ...

Optimization of UA of heat exchangers and BOG compressor exit pressure of LNG boil-off gas reliquefaction system using exergy analysis

NASA Astrophysics Data System (ADS)

Kochunni, Sarun Kumar; Ghosh, Parthasarathi; Chowdhury, Kanchan

2015-12-01

Boil-off gas (BOG) generation and its handling are important issues in Liquefied natural gas (LNG) value chain because of economic, environment and safety reasons. Several variants of reliquefaction systems of BOG have been proposed by researchers. Thermodynamic analyses help to configure them and size their components for improving performance. In this paper, exergy analysis of reliquefaction system based on nitrogen-driven reverse Brayton cycle is carried out through simulation using Aspen Hysys 8.6®, a process simulator and the effects of heat exchanger size with and without related pressure drop and BOG compressor exit pressure are evaluated. Nondimensionalization of parameters with respect to the BOG load allows one to scale up or down the design. The process heat exchanger (PHX) requires much higher surface area than that of BOG condenser and it helps to reduce the quantity of methane vented out to atmosphere. As pressure drop destroys exergy, optimum UA of PHX decreases for highest system performance if pressure drop is taken into account. Again, for fixed sizes of heat exchangers, as there is a range of discharge pressures of BOG compressor at which the loss of methane in vent minimizes, the designer should consider choosing the pressure at lower value.

Tectonic controls of transient landscapes in the Bhutan Himalaya

NASA Astrophysics Data System (ADS)

Adams, B. A.; Whipple, K. X.; Hodges, K. V.; Van Soest, M. C.; Heimsath, A. M.

2013-12-01

Previous research has identified many landscapes within the Himalaya that are not easily explained by classical critical taper models of orogenic wedges. One of the most striking examples is the sharp physiographic transition between the more subdued landforms of the Lower Himalayan ranges and the Higher Himalayan ranges to the north in Nepal. This transition has been attributed to several potential causes: changes in the rheology of rocks at depth, a ramp in the basal detachment of the orogenic wedge, a blind duplex, or a north-dipping, surface-breaking thrust fault. A similar, but more subdued transition marks the northern margin of perched, low-relief landscape patches found at ca. 3000 m in Bhutan. These low-relief surfaces, characterized by bogs and thick saprolites at the surface, overlie piggyback basins within the evolving orogenic wedge, filled with hundreds of meters of colluvial and alluvial deposits. The southern boundaries of the low-relief surfaces are less regular than the physiographic transition at their northern boundaries. The surfaces occur at similar elevations but are not continuous geographically, having been dissected by a series of river systems draining southward from the crest of the range. Pronounced knickpoints have formed at the southern margins of the low-relief surfaces. Our work suggests that there is a young (Pliocene-Pleistocene) fault system coincident with the physiographic transition in Bhutan. This high-angle, north-dipping structure, the Lhuentse fault, has minor normal-sense offset and could not have been responsible for differential uplift of the rugged terrain (in the hanging wall) relative to the low-relief landscape (in the footwall). The Lhuentse fault is coincident with the back limb of a previously inferred blind duplex at depth, and thus may be associated with active deformation on a rotated horse within the duplex. This duplex may also be responsible for the creation of the low-relief landscapes to the south of the Lhuentse fault due to upstream tilting in the back limb of the antiformal rock uplift pattern. Erosion patterns modeled on the basis of newly acquired 40Ar/39Ar and (U-Th)/He thermochronometric data as well as basin-average erosion rates from detrital cosmogenic nuclide concentrations are consistent with this hypothesis. We used a landscape evolution model (CHILD) to track landscape response to an imposed antiformal rock uplift gradient produced by an active duplex at depth. Rotation associated with the back limb of such a duplex causes aggradation, surface uplift, and headward migration of knickpoints. The wedge of sediment deposited during fluvial aggradation migrates northward beyond the back limb where uplift lessens. At this position in the landscape, a subdued physiographic transition develops in the model, similar to the one observed in Bhutan. Our modeling suggests that the presence and juxtaposition of low-relief landscapes and a physiographic transition, and our observed distribution of erosion rates can be explained by a single, simple mechanism related to the growth of a blind duplex.

Large scale in-situ BOrehole and Geofluid Simulator (i.BOGS) for the development and testing of borehole technologies at reservoir conditions

NASA Astrophysics Data System (ADS)

Duda, Mandy; Bracke, Rolf; Stöckhert, Ferdinand; Wittig, Volker

2017-04-01

A fundamental problem of technological applications related to the exploration and provision of geothermal energy is the inaccessibility of subsurface processes. As a result, actual reservoir properties can only be determined using (a) indirect measurement techniques such as seismic surveys, machine feedback and geophysical borehole logging, (b) laboratory experiments capable of simulating in-situ properties, but failing to preserve temporal and spatial scales, or vice versa, and (c) numerical simulations. Moreover, technological applications related to the drilling process, the completion and cementation of a wellbore or the stimulation and exploitation of the reservoir are exposed to high pressure and temperature conditions as well as corrosive environments resulting from both, rock formation and geofluid characteristics. To address fundamental and applied questions in the context of geothermal energy provision and subsurface exploration in general one of Europe's largest geoscientific laboratory infrastructures is introduced. The in-situ Borehole and Geofluid Simulator (i.BOGS) allows to simulate quasi scale-preserving processes at reservoir conditions up to depths of 5000 m and represents a large scale pressure vessel for iso-/hydrostatic and pore pressures up to 125 MPa and temperatures from -10°C to 180°C. The autoclave can either be filled with large rock core samples (25 cm in diameter, up to 3 m length) or with fluids and technical borehole devices (e.g. pumps, sensors). The pressure vessel is equipped with an ultrasound system for active transmission and passive recording of acoustic emissions, and can be complemented by additional sensors. The i.BOGS forms the basic module for the Match.BOGS finally consisting of three modules, i.e. (A) the i.BOGS, (B) the Drill.BOGS, a drilling module to be attached to the i.BOGS capable of applying realistic torques and contact forces to a drilling device that enters the i.BOGS, and (C) the Fluid.BOGS, a geofluid reactor for the composition of highly corrosive geofluids serving as synthetic groundwater / pore fluid in the i.BOGS. The i.BOGS will support scientists and engineers in developing instruments and applications such as drilling tooling and drillstrings, borehole cements and cementation procedures, geophysical tooling and sensors, or logging/measuring while drilling equipment, but will also contribute to optimized reservoir exploitation methods, for example related to stimulation techniques, pumping equipment and long-term reservoir accessibility.

Measuring restoration progress using pore- and surface-water chemistry across a chronosequence of formerly afforested blanket bogs.

PubMed

Gaffney, Paul P J; Hancock, Mark H; Taggart, Mark A; Andersen, Roxane

2018-08-01

During the restoration of degraded bogs and other peatlands, both habitat and functional recovery can be closely linked with nutrient cycling, which is reflected in pore- and surface-water chemistry. Several peatland restoration studies have shown that the time required for recovery of target conditions is slow (>10 years); for heavily-impacted, drained and afforested peatlands of northern Scotland, recovery time is unknown. We monitored pore- and surface-water chemistry across a chronosequence of formerly drained, afforested bog restoration sites spanning 0-17 years, using a space-for-time substitution, and compared them with open blanket bog control sites. Our aims were to measure rate of recovery towards bog conditions and to identify the best suite of water chemistry variables to indicate recovery. Our results show progress in recovery towards bog conditions over a 0-17 year period post-restoration. Elements scavenged by trees (Mg, Na, S) completely recovered within that period. Many water chemistry variables were affected by the restoration process itself, but recovered within 11 years, except ammonium (NH 4 + ), Zn and dissolved organic carbon (DOC) which remained elevated (when compared to control bogs) 17 years post restoration. Other variables did not completely recover (water table depth (WTD), pH), exhibiting what we term "legacy" effects of drainage and afforestation. Excess N and a lowered WTD are likely to slow the recovery of bog vegetation including key bog plants such as Sphagnum mosses. Over 17 years, we measured near-complete recovery in the chemistry of surface-water and deep pore-water but limited progress in shallow pore-water. Our results suggest that at least >17 years are required for complete recovery of water chemistry to bog conditions. However, we expect that newer restoration methods including conifer harvesting (stem plus brash) and the blocking of plough furrows (to increase the WTD) are likely to accelerate the restoration process (albeit at greater cost); this should be evaluated in future studies. We conclude that monitoring pore- and surface-water chemistry is useful in terms of indicating recovery towards bog conditions and we recommend monitoring WTD, pH, conductivity, Ca, NH 4 + , phosphate (PO 4 3- ), K, DOC, Al and Zn as key variables. Copyright © 2018 Elsevier Ltd. All rights reserved.

Thermal modelling of stepwise anatexis in a thrust-thickened sialic crust

USGS Publications Warehouse

Zen, E.-A.

1988-01-01

One-dimensional modelling of the thermal history of a sialic crust thickened by multiple overstack thrusting of upper crustal material shows that anatexis is likely. both the uplift rate and the length of the incubation period between end of tectonism and start of uplift are important controls on the amount and temperature of the melt. Heat of fusion does not significantly affect the long-term thermal structure of the crust if the melt is not extracted because only a small fraction of conductive heat is converted to latent heat, though short-term thermal effects of latent heat can be locally important. Model results show that commonly <15% of mantle heat flux is converted to latent heat; even during peak melting in the most productive models, less than half of incremental mantle flux is converted. The results have obvious implications on the acceptability of proposed heat sources for crustal anatexis. Fusion could retard crustal temperature rise by nearly 100??C, but the system would recover except for situations of very rapid uplift. Understanding of the thermal evolution of a burial-uplift system requires knowledge not only of the timing of anatexis but of the pooling and movement of the magma, as well as the duration and nature of the incubation period; we are poorly equipped to measure these events. The model predicts that the characteristic time for anatexis is a thickened sialic crust is several tens of millions of years, comparable to the time lapse between orogenies; in making geological interpretations of magmatism, this time lag must be considered. -Author

Airborne Electromagnetic Mapping of Peatlands: a Case Study in Norway.

NASA Astrophysics Data System (ADS)

Silvestri, S.; Viezzoli, A.; Pfaffhuber, A. A.; Vettore, A.

2017-12-01

Peatlands are extraordinary reservoirs of organic carbon that can be found over a wide range of latitudes, in tropical, to temperate, to (sub)polar climates. According to some estimates, the carbon stored in peatlands almost match the atmospheric carbon pool. Peatlands degradation due to natural and anthropogenic factors releases every year large amount of CO2 and other green house gasses into the atmosphere. The conservation of peatlands is therefore a key measure to reduce emissions and to mitigate climate change. An effective plan to prevent peatlands degradation must move from a precise estimate of the volume of peat stored across vast territories around the world. One example are the several bogs that characterize large surfaces in Norway. Our research combines the use of high spatial resolution satellite optical data with Airborne Electromagnetic (AEM) and field measurements in order to map the extension and thickness of peat in Brøttum, Ringsaker province, Norway. The methodology allows us to quantify the volume of peat as well as the organic carbon stock. The variable thickness typical of Norwegian bogs allows us to test the limits of the AEM methodology in resolving near surface peat layers. This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 747809. Start date: 1 June 2017. Duration: 24 months

Water exchange in raised bogs: revised views especially in relation to biogeochemistry

NASA Astrophysics Data System (ADS)

Sirin, Andrey; Kravchenko, Irina; Yurova, Alla; Markina, Anastasiya

2017-04-01

Raised bogs are one of the most common and exciting mire type within the boreal zone and appear in the other zones including mountain regions in the tropics. They receive water and nutrients from the atmosphere and pore water stored in their domes is spaced above the surrounding area (up to 10 m in height). Traditionally it is assumed that water flow occurs mainly in a peat layer near to the surface and water transport is negligible in deeper layers (lvanov, 1981; Ingram, 1982; etc.). The «acrotelm/catotelm» paradigm on active and inert horizons for the peat above and below the lowest water level is still widely spread in peatland hydrology. However, recent studies have shown that deep water movement is much more dynamic in raised bogs than was previously thought (Sirin et al., 1997, Reeve et al., 2000; etc.). Relying on isotope studies we conclude that all the mounded strata of the raised bogs have relatively active water exchange although water residence time changes with depth. The study included two raised bogs, representing different typical hydrological conditions (underlain by outwash sands and moraine clay) at the Zapadnaya Dvina Peatland Field Station of the Institute of Forest Science RAS located 400 km west of Moscow (56 N, 32 E). Peatlands, among which raised bogs dominate, constitute > 30% of the area, and maximum peat thickness exceeds 7 m. To evaluate water residence time in peat strata specially determined mathematical model which include the equations of water mass and tritium balance, imbedded in a conceptual framework of water dynamics within a raised bog peat body, have been developed and tested. The results from isotope studies (3H, 18O, 2H) were additionally supported by geochemical (pH, Eh, electrical conductivity) and temperature long term monitoring, as well as dissolved CO2 and CH4 monitoring within vertical profiles of the studied raised bogs (Sirin et al., 1998). Later it was also supported by microbiology data of methane cycle in the profile of peat bogs (Kravchenko, Sirin, 2007). The obtained results confirm that the hydrological stratification of peat bogs is a more complicated picture than previously thought and need to be considered.

Mössbauer studies of subfossil oak

NASA Astrophysics Data System (ADS)

van Bürck, Uwe; Wagner, Friedrich E.; Lerf, Anton

2012-03-01

Subfossil oak wood found in a dried-up bog in Bavaria, Germany, was studied by Mössbauer spectroscopy. The bog oaks contain substantial amounts of iron taken up from the bog waters and presumably forming complexes with the tanning agents in the oak wood. The iron is mainly Fe3 + and much of this exhibits an uncommonly large quadrupole splitting of up to 1.6 mm/s that can tentatively be explained by the formation of oxo-bridged iron dimers. Only rarely, mainly in the dense wood of the roots of bog oaks, was divalent iron found. When the wood was ground to a powder the divalent iron oxidized to Fe3 + within hours. This suggests that iron is taken up from the bog water as Fe2 + and oxidizes only when the wood emerges from the water and comes into contact with air.

Interactions between Nitrogen Fixation and Methane Cycling in Northern Minnesota Peat Bogs

NASA Astrophysics Data System (ADS)

Warren, M. J.; Gaby, J. C.; Lin, X.; Morton, P. L.; Kostka, J. E.; Glass, J. B.

2014-12-01

Peatlands cover only 3% of the Earth's surface, yet store a third of soil carbon. Increasing global temperatures have the potential to change peatlands from a net sink to a net source of atmospheric carbon. N is a limiting nutrient in oligotrophic Sphagnum-dominated peatlands and biological N2 fixation likely supplies a significant but unknown fraction of N inputs. Moreover, environmental controls on diazotrophic community composition in N-limited peatlands are poorly constrained. Thus, improved understanding of feedbacks between the CH4 and N cycles is critical for predicting future changes to CH4 flux from peat bogs. We coupled measurements of N2 fixation activity measured by the acetylene (C2H2) reduction assay (ARA) with molecular analyses of expression and diversity of nifH genes encoding the molybdenum (Mo)-containing nitrogenase from two peat bogs in the Marcell Experimental Forest, Minnesota, USA. The top 10 cm of peat was sampled from the high CH4 flux S1 bog and the low CH4 flux Zim bog in April and June 2014. Despite similar N concentrations in the top 10 cm of both bogs (0.5-1.0 μM NO2-+NO3- and 2-3 μM NH4+), the S1 bog displayed variable ARA activity (1-100 nmol C2H4 h-1 g-1) whereas the Zim bog had consistently low ARA activity (<1 nmol C2H4 h-1 g-1). Highest ARA activity was measured in June from S1 bog hollows with higher moisture content incubated without O2 in the light (20-100 nmol C2H4 h-1 g-1). Dissolved Fe (1-25 μM) was higher in hollow vs. hummock samples, and at S1 vs. Zim bog, while dissolved V (4-14 nM) was consistently higher than Mo (1-4 nM), suggesting that alternative V or Fe-containing nitrogenases might be present in these bogs. In contrast, Cu, an essential micronutrient for aerobic methanotrophs, was higher in hummocks (25-48 nM) than hollows (6-17 nM). The facultative methanotroph Methylocella was the dominant diazotroph in the S1 bog based on high throughput next generation sequencing of nifH cDNA amplicons. Given previous reports of C2H2 inhibition of methanotrophy, we measured CH4 consumption in the presence or absence of 1% C2H2. Preliminary results suggest minimal effect of C2H2 on CH4 oxidation. Future measurements of 15N2 incorporation coupled to molecular analysis will elucidate whether methanotroph diazotrophy was suppressed by C2H2 in ARA incubations.

The effects of permafrost thaw on soil hydrologic, thermal, and carbon dynamics in an Alaskan peatland

USGS Publications Warehouse

O'Donnell, Jonathan A.; Jorgenson, M. Torre; Harden, Jennifer W.; McGuire, A. David; Kanevskiy, Mikhail Z.; Wickland, Kimberly P.

2012-01-01

Recent warming at high-latitudes has accelerated permafrost thaw in northern peatlands, and thaw can have profound effects on local hydrology and ecosystem carbon balance. To assess the impact of permafrost thaw on soil organic carbon (OC) dynamics, we measured soil hydrologic and thermal dynamics and soil OC stocks across a collapse-scar bog chronosequence in interior Alaska. We observed dramatic changes in the distribution of soil water associated with thawing of ice-rich frozen peat. The impoundment of warm water in collapse-scar bogs initiated talik formation and the lateral expansion of bogs over time. On average, Permafrost Plateaus stored 137 ± 37 kg C m-2, whereas OC storage in Young Bogs and Old Bogs averaged 84 ± 13 kg C m-2. Based on our reconstructions, the accumulation of OC in near-surface bog peat continued for nearly 1,000 years following permafrost thaw, at which point accumulation rates slowed. Rapid decomposition of thawed forest peat reduced deep OC stocks by nearly half during the first 100 years following thaw. Using a simple mass-balance model, we show that accumulation rates at the bog surface were not sufficient to balance deep OC losses, resulting in a net loss of OC from the entire peat column. An uncertainty analysis also revealed that the magnitude and timing of soil OC loss from thawed forest peat depends substantially on variation in OC input rates to bog peat and variation in decay constants for shallow and deep OC stocks. These findings suggest that permafrost thaw and the subsequent release of OC from thawed peat will likely reduce the strength of northern permafrost-affected peatlands as a carbon dioxide sink, and consequently, will likely accelerate rates of atmospheric warming.

The new European Competence Centre for Moor and Climate - A European initiative for practical peat bog and climate protection

NASA Astrophysics Data System (ADS)

Smidt, Geerd; Tänzer, Detlef

2013-04-01

The new European Competence Centre for Moor and Climate (EFMK) is an initiative by different local communities, environmental protection NGOs, agricultural services, and partners from the peat and other industries in Lower Saxony (Germany). The Centre aims to integrate practical peat bog conservation with a focus on green house gas emission after drainage and after water logging activities. Together with our partners we want to break new ground to protect the remaining bogs in the region. Sphagnum mosses will be produced in paludiculture on-site in cooperation with the local peat industry to provide economic and ecologic alternatives for peat products used in horticulture business. Land-use changes are needed in the region and will be stimulated in cooperation with agricultural services via compensation money transfers from environmental protection funds. On a global scale the ideas of Carbon Credit System have to be discussed to protect the peat bogs for climate protection issues. Environmental education is an important pillar of the EFMK. The local society is invited to explore the unique ecosystem and to participate in peat bog protection activities. Future generations will be taught to understand that the health of our peat bogs is interrelated with the health of the local and global climate. Besides extracurricular classes for schools the centre will provide infrastructure for Master and PhD students, as well for senior researchers for applied research in the surrounding moor. International partners in the scientific and practical fields of peat bog ecology, renaturation, green house gas emissions from peat bogs, and environmental policy are invited to participate in the European Competence Center for Moor and Climate.

Increased tree establishment in Lithuanian peat bogs--insights from field and remotely sensed approaches.

PubMed

Edvardsson, Johannes; Šimanauskienė, Rasa; Taminskas, Julius; Baužienė, Ieva; Stoffel, Markus

2015-02-01

Over the past century an ongoing establishment of Scots pine (Pinus sylvestris L.), sometimes at accelerating rates, is noted at three studied Lithuanian peat bogs, namely Kerėplis, Rėkyva and Aukštumala, all representing different degrees of tree coverage and geographic settings. Present establishment rates seem to depend on tree density on the bog surface and are most significant at sparsely covered sites where about three-fourth of the trees have established since the mid-1990s, whereas the initial establishment in general was during the early to mid-19th century. Three methods were used to detect, compare and describe tree establishment: (1) tree counts in small plots, (2) dendrochronological dating of bog pine trees, and (3) interpretation of aerial photographs and historical maps of the study areas. In combination, the different approaches provide complimentary information but also weigh up each other's drawbacks. Tree counts in plots provided a reasonable overview of age class distributions and enabled capturing of the most recently established trees with ages less than 50 years. The dendrochronological analysis yielded accurate tree ages and a good temporal resolution of long-term changes. Tree establishment and spread interpreted from aerial photographs and historical maps provided a good overview of tree spread and total affected area. It also helped to verify the results obtained with the other methods and an upscaling of findings to the entire peat bogs. The ongoing spread of trees in predominantly undisturbed peat bogs is related to warmer and/or drier climatic conditions, and to a minor degree to land-use changes. Our results therefore provide valuable insights into vegetation changes in peat bogs, also with respect to bog response to ongoing and future climatic changes. Copyright © 2014 Elsevier B.V. All rights reserved.

Two Years Necessary for Successful Natural Seeding in Nonbrushy Black Spruce Bogs

Treesearch

Elon S. Verry; Arthur E. Elling

1978-01-01

Natural seeding in a strip-cut black spruce bog was adequate, averaging 1,800 stems per acre and 80 percent milacre stocking. natural seeding in a completely cut bog was inadequate, averaging 630 stems per acre and 40 percent milacre stocking. Slash was removed to expose sphagnum seedbeds in both cases. Progressive cutting every other year is recommended.

Peat bogs and their organic soils: Archives of atmospheric change and global environmentalsignificance (Philippe Duchaufour Medal Lecture)

NASA Astrophysics Data System (ADS)

Shotyk, William

2013-04-01

A bog is much more than a waterlogged ecosystem where organic matter accumulates as peat. Peatlands such as bogs represent a critical link between the atmosphere, hydrosphere, and biosphere. Plants growing at the surface of ombrotrophic bogs receive nutrients exclusively from the atmosphere. Despite the variations in redox status caused by seasonal fluctuations in depth to water table, the low pHof the waters, and abundance of dissolved organic matter, bogs preserve a remarkably reproducible history of atmospheric pollution, climate change, landscape evolution and human history. For example, peat cores from bogs in Europe and North America have provided detailed reconstructions of the changing rates and sources of Ag, Cd, Hg, Pb, Sb, and Tl, providing new insights into the geochemical cycles of these elements, including the massive perturbations induced by human activities beginning many thousands of years ago. Despite the low pH, and perhaps because of the abundance of dissolved organic matter, bogs preserve many silicate and aluminosilicate minerals which renders them valuable archives of atmospheric dust deposition and the climate changes which drive them. In the deeper, basal peat layers of the bog, in the minerotrophic zone where pore waters are affected bymineral-water interactions in the underlying and surrounding soils and sediments, peat serves as animportant link to the hydrosphere, efficiently removing from the imbibed groundwaters such trace elements as As, Cu, Mo, Ni, Se, V, and U. These removal processes, while incompletely understood, are so effective that measuring the dissolved fraction of trace elements in the pore waters becomes a considerable challenge even for the most sophisticated analytical laboratories. While the trace elements listed above are removed from groundwaters (along with P and S), elements such as Fe and Mn are added to the waters because of reductive dissolution, an important first step in the formation of lacustrine Fe and Mn nodules. While these important chemical reactions have taken place silently and imperceptibly over millenia acrossthe Earth wherever climate and water allow bogs to form, at the same time, peat bogs represent an important component of the biosphere and provide a home to many unique plants and animals, thereby contributing to the vast biodiversity found on Earth.

UAV based 3D digital surface model to estimate paleolandscape in high mountainous environment

NASA Astrophysics Data System (ADS)

Mészáros, János; Árvai, Mátyás; Kohán, Balázs; Deák, Márton; Nagy, Balázs

2016-04-01

Our method to present current state of a peat bog was focused on the possible use of a UAV-system and later Structure-from-motion algorithms as processing technique. The peat bog site is located on the Vinderel Plateau, Farcǎu Massif, Maramures Mountains (Romania). The peat bog (1530 m a.s.l., N47°54'11", E24°26'37") lies below Rugasu ridge (c. 1820 m a.s.l.) and the locality serves as a conservation area for fallen down coniferous trees. Peat deposits were formed in a landslide concavity on the western slope of Farcǎu Massif. Nowadays the site is surrounded by a completely deforested landscape, and Farcǎu Massif lies above the depressed treeline. The peat bog has an extraordinary geomorphological situation, because a gully reached the bog and drained the water. In the recent past sedimentological and dendrochronological researches have been initiated. However, an accurate 3D digital surface model also needed for a complex paleoenvironmental research. Last autumn the bog and its surroundings were finally surveyed by a multirotor UAV developed in-house based on an open-source flight management unit and its firmware. During this survey a lightweight action camera (mainly to decrease payload weight) was used to take aerial photographs. While our quadcopter is capable to fly automatically on a predefined flight route, several over- and sidelapping flight lines were generated prior to the actual survey on the ground using a control software running on a notebook. Despite those precautions, limited number of batteries and severe weather affected our final flights, resulting a reduced surveyed area around peat bog. Later, during the processing we looked for a reliable tool which powerful enough to process more than 500 photos taken during flights. After testing several software Agisoft PhotoScan was used to create 3D point cloud and mesh about bog and its environment. Due to large number of photographs PhotoScan had to be configured for network processing to get reliable results and resolution. Based on the sediment layers of the peat bog together with the generated 3D surface model the paleoenvironment, the largest paleowater level can be reconstructed and we can estimate the dimension of the landslide which created the basin of the peat bog.

Can restoration convert a degraded bog in southern Bavaria to a carbon sink and climate cooler?

NASA Astrophysics Data System (ADS)

Förster, Christoph; Drösler, Matthias

2014-05-01

The peatland area of Germany is about 14.000 km² (Succow & Joosten 2001) with 8% natural like bogs and 4% natural like fens (Höper 2006). All other peatland areas are more or less intensively used and thus, lost their sink function for carbon. If, theoretically, all German peatlands would be rewetted, this restoration would lead to a carbon mitigation of 9.5 Mio. t CO2-C equivalents (Freibauer et al. 2009). In test areas like the studied bog, the viability and potential of peatland restoration for climate mitigation can be proofed. The investigated bog is situated close to the Bavarian Alps; one part of this bog is extensively used and had been rewetted in 1993 except of a small stripe; management was stopped totally at another stripe. The second part of this bog had been drained without any further use. Here a Calluna heath established, accompanied by Pine trees. The restoration of this bog heath was done in two time steps; here a chronosequence of succession after restoration at different water table levels was investigated. To get to the greenhouse gas (GHG) balances of CO2 CH4 and N2O, gas flux measurements were done for two years using the chamber technique of Drösler (2005). At both areas, the degraded sites were sources for GHG (+203 to +736 g CO2-C-equiv m-2 a-1). Restoration reduced these emissions depending on water table and succession of bog species (-51 to +557 g CO2-C-equiv m-2 a-1). Depending on the vegetation's vitality GHG balances of already established natural like sites varied in between the years (-189 to +264 g CO2-C-equiv m-2 a-1) mainly driven by the oscillation of their water table. Stop of management and development of Sphagnum communities turned most of the sites into sinks for GHG (-216 to +7 g CO2-C-equiv m-2 a-1). Thus restoration turned degraded bogs efficiently to carbon sinks and climate coolers in dependence of a proper water table management, withdrawal of land use and vegetation succession. Key words: bog, greenhouse gases, restoration, water table

Impact of simulated atmospheric nitrogen deposition on nutrient cycling and carbon sink via mycorrhizal fungi in two nutrient-poor peatlands

NASA Astrophysics Data System (ADS)

Larmola, Tuula; Kiheri, Heikki; Bubier, Jill L.; van Dijk, Netty; Dise, Nancy; Fritze, Hannu; Hobbie, Erik A.; Juutinen, Sari; Laiho, Raija; Moore, Tim R.; Pennanen, Taina

2017-04-01

Peatlands store one third of the global soil carbon (C) pool. Long-term fertilization experiments in nutrient-poor peatlands showed that simulated atmospheric nitrogen (N) deposition does not enhance ecosystem C uptake but reduces C sink potential. Recent studies have shown that a significant proportion of C input to soil in low-fertility forests entered the soil through mycorrhizal fungi, rather than as plant litter. Is atmospheric N deposition diminishing peatland C sink potential due to the suppression of ericoid mycorrhizal fungi? We studied how nutrient addition influences plant biomass allocation and the extent to which plants rely on mycorrhizal N uptake at two of the longest-running nutrient addition experiments on peatlands, Whim Bog, United Kingdom, and Mer Bleue Bog, Canada. We determined the peak growing season aboveground biomass production and coverage of vascular plants using the point intercept method. We also analyzed isotopic δ15N patterns and nutrient contents in leaves of dominant ericoid mycorrhizal shrubs as well as the non-mycorrhizal sedge Eriophorum vaginatum under different nutrient addition treatments. The treatments receive an additional load of 1.6-6.4 N g m-2 y-1 either as ammonium (NH4) nitrate (NO3) or NH4NO3 and with or without phosphorus (P) and potassium (K), alongside unfertilized controls. After 11-16 years of nutrient addition, the vegetation structure had changed remarkably. Ten of the eleven nutrient addition treatments showed an increase of up to 60% in total vascular plant abundance. Only three (NH4Cl, NH4ClPK, NaNO3PK) of the nutrient addition treatments showed a concurrent decrease of down to 50% in the relative proportion of ericoid mycorrhizal shrubs to total vascular plant abundance. The response to nutrient load may be explained by the water table depth, the form of N added and whether N was added with PK. Shrubs were strong competitors at the dry Mer Bleue bog while sedges gained in abundance at the wetter Whim bog. Our results also suggest that the impacts of reduced and oxidized N on above ground biomass of ericoid shrubs differ and that plants have become increasingly P limited under high simulated atmospheric N deposition. Combined with mycorrhizal abundance and foliar isotopic δ15N patterns, the data will allow us to estimate the extent to which plants rely on mycorrhizal N uptake and whether mycorrhizal responses are linked to diminished C sink potential. This evidence is needed to establish critical loads for C sink potential in peatlands.

Effects of permafrost thaw on nitrogen availability and plant nitrogen acquisition in Interior Alaska

NASA Astrophysics Data System (ADS)

Finger, R.; Euskirchen, E. S.; Turetsky, M.

2013-12-01

The degradation of ice-rich permafrost, which covers a large portion of Interior Alaska, typically leads to thermokarst and increases in soil saturation. As a result, conifer peat plateaus degrade and are often replaced by wet collapse scar bogs. This state change results in profound changes in regional hydrology, biogeochemical cycling, and plant community composition. Preliminary data suggest that permafrost thaw can increase surface soil inorganic nitrogen (IN) concentrations but it is still unknown whether these changes in nutrient availability are short-lived (pulse releases) and whether or not they impact collapse scar vegetation composition or productivity, particularly as collapse scars undergo succession with time-after-thaw. Therefore we are currently examining changes in plant community composition, N availability and plant N acquisition along three thermokarst gradients in Interior Alaska. Each gradient is comprised of a forested permafrost peat plateau, adjacent ecotones experiencing active permafrost degradation (including a collapsing forest canopy and a saturated moat), and a collapse scar bog where permafrost has completely degraded. We predicted that IN concentrations would be highest along the active thaw margin, and lowest in the peat plateau. We also predicted that IN concentrations would be positively related to shifts in vegetation community composition, nutrient use efficiency (NUE) and tissue 15N concentrations. Preliminary results have shown that IN concentrations increase in newer collapse scar features as well as with thaw depth. Our data also show a shift from feather moss and ericaceous shrub-dominate understories in the permafrost plateau to Sphagnum and sedge dominated thaw ecotone and bog communities. Further successional development of the collapse scar bog results in the reintroduction of small evergreen and deciduous shrubs as the peat mat develops. Over time, collapse scar succession and peat accumulation appears to lead to progressive N limitations, resulting in the dominance of plants with higher NUE. This likely has implications for plant litter quality, and could inhibit decomposition processes. We are collecting additional data to compare species-level NUE and nutrient resorption efficiency. We also will measure δ15N of aboveground plant organs, roots, soil, and pore water to explore sources of plant N, which we expect will influenced rooting depth as permafrost thaws as well as differences in mycorrhizal associations along our thaw gradient. Because thawing permafrost soils are anticipated to mobilize large amounts of N from soils, our results will improve our understanding of how permafrost thaw influences vegetation and soil N pools, soil N availability, and plant nutrition.

Genesis of peat-bog soils in the northern taiga spruce forests of the Kola Peninsula

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

Nikonov, V.V.

1981-01-01

The characteristics of soil formation processes in the Peat-Bog soils of waterlogged spruce phytocenoses on the Kola Peninsula are investigated. It is found that the ash composition of the peat layer is determined primarily by the composition of the buried plant residues. The effect of the chemical composition of water feeding the peat bogs is determined. (Refs. 7).

SPRUCE S1-Bog Phenology Movies, 2010-2016

DOE Data Explorer

Hanson, P. J. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; Riggs, J. S. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; Hook, L. A. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; Nettles, W. R. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.

2015-01-01

This data set provides annual movies created from daily and twice daily images of vegetation stands in the S1 Bog showing the seasonal changes of vegetation and appearance and disappearance of snow for the period June 2010 through December 2015. Compiled movies are useful for examining the phenology of the bog and the changes to the landscape as experimental facilities have been constructed.

High-resolution Record of Holocene Climate, Vegetation, and Fire from a Raised Peat Bog, Prince Edward Island, Canadian Maritimes

NASA Astrophysics Data System (ADS)

Peros, M. C.; Chan, K.; Ponsford, L.; Carroll, J.; Magnan, G.

2014-12-01

Raised peat bogs receive all precipitation and nutrients from the atmosphere and are thus widely used archives for information on past environments and climates. In this paper we provide high-resolution multi-proxy data from a raised bog from northeastern Prince Edward Island, located in the Gulf of St. Lawrence, Canada. We studied testate amoeba (a proxy for water table depth), macrocharcoal (a proxy for local-scale fire), peat humification (a proxy for decomposition), plant macrofossils (indicative of local-scale vegetation), and organic matter content (yielding carbon accumulation rates) from a 5.5 m long core lifted from the center of Baltic Bog. Eleven AMS radiocarbon dates show that peat accumulation began before 9000 cal yr BP and continued almost uninterrupted until the present. The macrofossil data show that a transition from a sedge-dominated fen to a sphagnum-dominated bog occurred around 8000 cal yr BP, and sphagnum remained dominant in the bog throughout most of the Holocene. A testate amoeba-based reconstruction of water table depth indicates that conditions were drier during the early Holocene (~8000 to 5000 cal yr BP) and became gradually wetter into the late Holocene. In addition, a number of higher frequency shifts in precipitation are inferred throughout the Holocene on the basis of the testate amoeba and humification results. The macrocharcoal evidence indicates fire—probably in the surrounding forest—was relatively more common during the early Holocene, perhaps due to drier climate conditions. A large influx of charcoal at around 2000 cal yr BP suggests the presence of one or more major fires at this time, and a concurrent decrease in the rate of peat accumulation indicates the fire may have affected the bog itself. The data from Baltic Bog is broadly comparable to other proxy data (in particular pollen studies) from the Canadian Maritimes. This work is important because it: 1) helps us better understand the role of hydroclimatic variability in influencing peat bog ecosystems; and 2), represents one of the few peat-based records of Holocene paleoclimate from the region.

Functional traits of testate amoebae and multi-proxy data unveil exceptional Baltic bog ecohydrology, autogenic succession and climate change during the last 2000 years in CE Europe

NASA Astrophysics Data System (ADS)

Lamentowicz, Mariusz; Gałka, Mariusz; Tobolski, Kazimierz; Lamentowicz, Łukasz; Ersek, Vasile; Jassey, Vincent E. J.; van der Knaap, Willem O.

2017-04-01

We studied two peat cores from the Baltic raised bog (Mechacz Wielki in NE Poland). We aimed to separate signal of extrinsic and intrinsic forcing of the raised bog development using multi-proxy high-resolution approach. Using testate amoebae transfer function, we found that the bog revealed exceptionally stable hydrological conditions during the last 2k with a relatively high water table and lack of local fire events that allowed for rapid peat accumulation (2.75 mm/year) in the bog. Furthermore, the strong correlation between pH and community-weighted mean of testate amoeba traits suggests that other variables than water-table depth play a role in driving microbial properties under stable hydrological conditions. There is a difference in hydrological dynamics in bogs between NW and NE Poland until ca CE 1500, after which the water table reconstructions possess more similarities. Our data suggest a common regional climatic forcing in Mechacz Wielki, Gązwa and Kontolanrahka. Though it may still be too early to attempt a regional summary of wetness change in the southern Baltic region, this study is a next step to better understand the long-term peatland palaeohydrology in NE Europe. We suggest that extrinsic factors (climate) played an important role as a driver in mire development during the bog stage (AD 500-2012). Our results also show how various functional traits relate to different environmental variables in a range of trophic and hydrological scenarios on long time scales.

Soil microbial community composition is correlated to soil carbon processing along a boreal wetland formation gradient

USGS Publications Warehouse

Chapman, Eric; Cadillo-Quiroz, Hinsby; Childers, Daniel L.; Turetsky, Merritt R.; Waldrop, Mark P.

2017-01-01

Climate change is modifying global biogeochemical cycles. Microbial communities play an integral role in soil biogeochemical cycles; knowledge about microbial composition helps provide a mechanistic understanding of these ecosystem-level phenomena. Next generation sequencing approaches were used to investigate changes in microbial functional groups during ecosystem development, in response to climate change, in northern boreal wetlands. A gradient of wetlands that developed following permafrost degradation was used to characterize changes in the soil microbial communities that mediate C cycling: a bog representing an “undisturbed” system with intact permafrost, and a younger bog and an older bog that formed following the disturbance of permafrost thaw. Reference 16S rRNA databases and several diversity indices were used to assess structural differences among these communities, to assess relationships between soil microbial community composition and various environmental variables including redox potential and pH. Rates of potential CO2 and CH4 gas production were quantified to correlate sequence data with gas flux. The abundance of organic C degraders was highest in the youngest bog, suggesting higher rates of microbial processes, including potential CH4 production. In addition, alpha diversity was also highest in the youngest bog, which seemed to be related to a more neutral pH and a lower redox potential. These results could potentially be driven by increased niche differentiation in anaerobic soils. These results suggest that ecosystem structure, which was largely driven by changes in edaphic and plant community characteristics between the “undisturbed” permafrost bog and the two bogs formed following permafrost thaw, strongly influenced microbial function.

Peat Bog Archives: from human history, vegetation change and Holocene climate, to atmospheric dusts and trace elements of natural and anthropogenic origin

NASA Astrophysics Data System (ADS)

Shotyk, William

2010-05-01

For at least two centuries, peat has been recognized as an excellent archive of environmental change. William Rennie (1807), for example, interpreted stratigraphic changes in Scottish bogs not only in terms of natural changes in paleoclimate, but was also able to identify environmental changes induced by humans, namely deforestation and the hydrological impacts which result from such activities. The use of bogs as archives of climate change in the early 20th century was accelerated by studies of fossil plant remains such as those by Lewis in Scotland, and by systematic investigations of pollen grains pioneered by von Post in Sweden. In Denmark, Glob outlined the remarkably well-preserved remains of bog bodies and associated artefacts (of cloth, wood, ceramic and metal) in Danish bogs. In Britain, Godwin provided an introduction to the use of bogs as archives of human history, vegetation change, and Holocene climate, with a more recent survey provided by Charman. Recent decades have provided many mineralogical studies of peat and there is growing evidence that many silicate minerals, whether derived from the surrounding watershed or the atmosphere (soil-derived dusts and particles emitted from volcanoes), also are well preserved in anoxic peatland waters. Similarly, geochemical studies have shown that a long list of trace metals, of both natural and anthropogenic origin, also are remarkably well preserved in peat bogs. Thus, there is growing evidence that ombrotrophic (ie 'rain-fed') peat bogs are reliable archives of atmospheric deposition of a wide range of trace elements, including conservative, lithogenic metals such as Al, Sc, Ti, Y, Zr, Hf and the REE, but also the potentially toxic Class B, or 'heavy metals' such as Cu, Ag, Hg, Pb, Sb and Tl. When high quality measurements of these elements is combined with accurate radiometric age dating, it becomes possible to create high resolution reconstructions of atmospheric soil dust fluxes, ancient and modern metal pollution, and Holocene climate change.

A carbon accumulation maximum during the Medieval Climate Anomaly in the world’s biggest bog, Siberia

NASA Astrophysics Data System (ADS)

Beilman, D.; MacDonald, G. M.

2009-12-01

The West Siberia Lowland is the most carbon-rich northern wetland region, holding an important portion of total northern peatland carbon (70 Gt of 270-450 Gt C) mainly in the southern lowland (44 Gt) in very large peatlands. The largest of these, the Great Vasyugan Bog complex, spans 63,252 km2 and alone holds ~11 Gt C. Our previous work has shown that recent-past growth of WSL peat C pool has been greatest in southern WSL in large peatlands close to the southern limit of peatland distribution. In this study, we investigate a Great Vasyugan site to investigate peat carbon sensitivity in two ways: 1) assess past changes in vegetation, species-specific 13C geochemistry, and rate of carbon accumulation relative to recent-past climate variation, and 2) assess the relative lability of this deep peat C through laboratory incubations. Carbon accumulation over the last 2000 years, a period of relatively consistent vegetation and litter inputs but variable local hydrology, reached a maximum between 1150 and 1350 AD during Medieval Climate Anomaly conditions. A carbon accumulation minimum occurred between about 1350 and 1550 AD. Regardless of depth, age, or rate of carbon burial, deep peat from between 30 and 230 cm below the surface showed a similar rate of potential aerobic respiration that changed little over 42 days of incubation. Taken together, these data suggest that in some peatlanlds warmer and hydrologically-variable conditions can promote long-term belowground carbon storage.

The formation and dust lifting processes associated with a large Saharan meso-scale convective system (MCS)

NASA Astrophysics Data System (ADS)

Roberts, Alex; Knippertz, Peter

2013-04-01

This work focusses on the meteorology that produced a large Mesoscale Convective System (MCS) and the dynamics of its associated cold pool. The case occurred between 8th-10th June 2010 and was initiated over the Hoggar and Aïr Mountains in southern Algeria and northern Niger respectively. The dust plume created covered parts of Algeria, Mali and Mauritania and was later deformed the by background flow and transported over the Atlantic and Mediterranean. This study is based on: standard surface observations (where available), ERA-Interim reanalysis, Meteosat imagery, MODIS imagery, Tropical Rainfall Measuring Mission (TRMM) rainfall estimates, Cloud Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO), CloudSat and a high resolution (3.3km) limited area simulation using the Weather Research and Forecasting (WRF) model. A variety of different processes appear to be important for the generation of this MCS and the spreading of the associated dusty cold pool. These include: the presence of a trough on the subtropical jet, the production of a tropical cloud plume, disruption to the structure of the Saharan heat low and the production of a Libyan high. These features produced moistening of the boundary layer and a convergence zone over the region of MCS initiation. Another important factor appears to have been the production of a smaller MCS and cold pool on the evening of the 7th June. This elevated low-level moisture and encouraged convective initiation the following day. Once triggered on the 8th June some cells grew and merged into a single large system that propagated south westward and produced a large cold pool that emanated from its northern edge. The cells on the northern edge of the system over the Hoggar grew and collapsed producing a haboob that spread over a large area. Cells further south continued to develop into the MCS and actively produce a cold pool over the system's lifetime. This undercut the dusty air from the earlier cold pool and forced dust high into the atmosphere. As well as the expected behaviour of a gravity current there also seems to be a complex relationship between the cold pool and diurnal variation in boundary layer structure. These include: (1) the production of nocturnal low-level jet in the area previously covered by the cold pool allowing for further dust uplift the following morning, (2) the development of a bore on the nocturnal boundary layer travelling ahead of the cold pool and capable of deflating dust further into the desert and (3) the production of bores on the nocturnal boundary layer by the collision of fronts formed through the collapse of the well mixed daytime boundary layer and nocturnal frontogenesis. It is hoped that this work will add to the understanding of the production of large Saharan MCSs and the processes that can influence their formation. Also it shows the complex dynamical interactions that occur within the Saharan boundary layer and how these might impact our understanding of dust uplift processes associated with the passage of MCSs.

SPRUCE S1 Bog Plant-Available Nutrients Assessed with Ion-Exchange Resins from 2011-2012 in the Southern End of the S1 Bog

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

Iversen, C. M.; Ontl, T. A.; Brice, D. J.

This data set consists of observations of plant-available nutrients assessed using ion-exchange resin capsules incubated serially in aerobic and anaerobic peat layers beginning in 2011. Data were collected from 2011 to 2012 (prior to the construction of the SPRUCE experimental plots) at the southern end of the S1 Bog at three depths in hollow microtopography only.

Microhabitat parameters and life-history characteristics of fallicambarus gordonz fitzpatrick, a crayfish associated with pitcher-plant bogs in southern Mississippi

Treesearch

Carol E. Johnston; Chester Figiel

1997-01-01

Fallicambarus gordoni, a crayfish found only in pitcher-plant bogs, is restricted to the DeSoto National Forest, Perry County, Mississippi, U.S.A. The species is active from late fall through late spring, and apparentiy estivates during the summer when bogs are dry. Ovigerous females were found in late fall and winter, and small juveniles were collected in February....

Soil data for a thermokarst bog and the surrounding permafrost plateau forest, located at Bonanza Creek Long Term Ecological Research Site, Interior Alaska

USGS Publications Warehouse

Manies, Kristen L.; Fuller, Christopher C.; Jones, Miriam C.; Waldrop, Mark P.; McGeehin, John P.

2017-01-19

Peatlands play an important role in boreal ecosystems, storing a large amount of soil organic carbon. In northern ecosystems, collapse-scar bogs (also known as thermokarst bogs) often form as the result of ground subsidence following permafrost thaw. To examine how ecosystem carbon balance changes with the loss of permafrost, we measured carbon and nitrogen storage within a thermokarst bog and the surrounding forest, which continues to have permafrost. These sites are a part of the Bonanza Creek Long Term Ecological Research (LTER) site and are located within Interior Alaska. Here, we report on methods used for core collection analysis as well as the cores’ physical, chemical, and descriptive properties.

SPRUCE Representing Northern Peatland Microtopography and Hydrology within the Community Land Model: Modeling Archive

DOE Data Explorer

Shi, X. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; Thornton, P. E. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; Ricciuto, D. M. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; Hanson, P. J. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; Mao, J. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; Sebestyen, S. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; Griffiths, N. A. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; Bisht, G. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.

2016-09-01

Here we provide model code, inputs, outputs and evaluation datasets for a new configuration of the Community Land Model (CLM) for SPRUCE, which includes a fully prognostic water table calculation for SPRUCE. Our structural and process changes to CLM focus on modifications needed to represent the hydrologic cycle of bogs environment with perched water tables, as well as distinct hydrologic dynamics and vegetation communities of the raised hummock and sunken hollow microtopography characteristic of SPRUCE and other peatland bogs. The modified model was parameterized and independently evaluated against observations from an ombrotrophic raised-dome bog in northern Minnesota (S1-Bog), the site for the Spruce and Peatland Responses Under Climatic and Environmental Change experiment (SPRUCE).

Using Macrofossils to Reconstruct Paleoenvironmental History of Cedar Swamp, High Point NJ

NASA Astrophysics Data System (ADS)

Buhler, K. M.; Peteet, D. M.

2016-12-01

Macrofossils from deep sediment cores taken from bog environments can reveal much about the paleoclimate of a certain site. A research study conducted by Niering in 1953 focused on the pollen records from Cedar Bog that, although are able to indicate which species were present regionally, are not able to establish the specific local vegetation of the site. By identifying and counting macrofossils from the core, we can determine the species growing in Cedar Bog in High Point State Park, NJ and utilize that data to reconstruct a paleoclimatic history at the highest elevation in New Jersey. We took a 6.5m core from Cedar Bog and, from that, used 4cm³ samples taken throughout the entire depth to wash through a 250um sieve and sift through at 60x magnification, identifying the macrofossils using an extensive Lamont Doherty Earth Observatory reference collection. Additionally, we tested for the percentage of organic matter through the core using loss on ignition. We found 5 zones throughout the core depth that indicate altering habitats. Beginning with low organic matter, less than 5%, the deepest part of the core has little vegetation but high rock content. The next zone introduced Chamaecyparis thyoides in the region and a period of changing organic matter. Following this comes a domination of aquatic plants and byrozoan statoblast and, afterwards, a shift towards sedges. The top of the core shows present day vegetation types from Cedar Bog, such as sphagnum moss and Tsuga canadensis, and 96% organic matter content. The lack of vegetation and high rock content, around 6.5m deep, signal erosion that took place after deglaciation. The vegetation types in zone 2 indicate deep lake/open landscape conditions. High aquatic vegetation and bryozoan statoblasts suggest a shallow lake. The site filled in to become a fen wetland as evidenced by the abundance of Scirpus and Cladium. The final zone signifies a bog habitat represented by the domination of sphagnum and Chamaedaphne. These shifts signal an altering landscape of Cedar Bog, evolving after deglaciation from a deep lake to a shallow lake, followed by a fen wetland and eventually into a modern bog habitat. Certain vegetation and organism data indicate climatic shifts at Cedar Bog that can uncover the paleoclimate for a site located at the highest elevation in New Jersey.

The core microbiome bonds the Alpine bog vegetation to a transkingdom metacommunity.

PubMed

Bragina, Anastasia; Berg, Christian; Berg, Gabriele

2015-09-01

Bog ecosystems fulfil important functions in Earth's carbon and water turnover. While plant communities and their keystone species Sphagnum have been well studied, less is known about the microbial communities associated with them. To study our hypothesis that bog plants share an essential core of their microbiome despite their different phylogenetic origins, we analysed four plant community plots with 24 bryophytes, vascular plants and lichen species in two Alpine bogs in Austria by 16S rDNA amplicon sequencing followed by bioinformatic analyses. The overall bog microbiome was classified into 32 microbial phyla, while Proteobacteria (30.8%), Verrucomicrobia (20.3%) and Planctomycetes (15.1%) belonged to the most abundant groups. Interestingly, the archaeal phylum Euryarcheota represented 7.2% of total microbial abundance. However, a high portion of micro-organisms remained unassigned at phylum and class level, respectively. The core microbiome of the bog vegetation contained 177 operational taxonomic units (OTUs) (150 526 seq.) and contributed to 49.5% of the total microbial abundance. Only a minor portion of associated core micro-organisms was host specific for examined plant groups (5.9-11.6%). Using our new approach to analyse plant-microbial communities in an integral framework of ecosystem, vegetation and microbiome, we demonstrated that bog vegetation harboured a core microbiome that is shared between plants and lichens over the whole ecosystem and formed a transkingdom metacommunity. All micro- and macro-organisms are connected to keystone Sphagnum mosses via set of microbial species, for example Burkholderia bryophila which was found associated with a wide spectrum of host plants and is known for a beneficial plant-microbe interaction. © 2015 John Wiley & Sons Ltd.

Investigation and Modeling of Cranberry Weather Stress.

NASA Astrophysics Data System (ADS)

Croft, Paul Joseph

Cranberry bog weather conditions and weather-related stress were investigated for development of crop yield prediction models and models to predict daily weather conditions in the bog. Field investigations and data gathering were completed at the Rutgers University Blueberry/Cranberry Research Center experimental bogs in Chatsworth, New Jersey. Study indicated that although cranberries generally exhibit little or no stomatal response to changing atmospheric conditions, the evaluation of weather-related stress could be accomplished via use of micrometeorological data. Definition of weather -related stress was made by establishing critical thresholds of the frequencies of occurrence, and magnitudes of, temperature and precipitation in the bog based on values determined by a review of the literature and a grower questionnaire. Stress frequencies were correlated with cranberry yield to develop predictive models based on the previous season's yield, prior season data, prior and current season data, current season data; and prior and current season data through July 31 of the current season. The predictive ability of the prior season models was best and could be used in crop planning and production. Further examination of bog micrometeorological data permitted the isolation of those weather conditions conducive to cranberry scald and allowed for the institution of a pilot scald advisory program during the 1991 season. The micrometeorological data from the bog was also used to develop models to predict daily canopy temperature and precipitation, based on upper air data, for grower use. Models were developed for each month for maximum and minimum temperatures and for precipitation and generally performed well. The modeling of bog weather conditions is an important first step toward daily prediction of cranberry weather-related stress.

SPRUCE S1 Bog Peat Depth Determined by Push Probe and GPR: 2009-2010

DOE Data Explorer

Slater, L. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; Hanson, P. J. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; Hook, L. A. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.

2012-01-01

This data set reports the thickness of peat for the S1 Bog measured directly with manual push probes on September 21 and 22, 2009, and measured by ground penetrating radar (GPR) across transects from January 26 to February 2, 2010 and June 2 to June 9, 2010. Also included are interpolated values of peat depth from both probe and GPR data for the S1 Bog at 1 meter square horizontal resolution.

Pattern of large raised bog formation in the South-Eastern Baltic Region during the Holocene: the case of Kaliningrad oblast

NASA Astrophysics Data System (ADS)

Napreenko-Dorokhova, T. V.; Napreenko, M. G.; Lisitzin, A. P.

2017-08-01

The results of complex investigations that have been carried out since 2007 in large bog ecosystems (Zehlau, Bolshoe Mokhovoe, and Koz'e) located in Kaliningrad oblast in two largest landscape areas, glaciolacustrine plains in the central part of the region and coastal lowlands of the southern coast of Curonian Lagoon and the delta of the Neman River, are presented. It is established that the intensive development of mires and their transition to the raised bog stage occurred in the territory of Kaliningrad oblast later than in most of the forest zone in European Russia, where this process was noted as early as during the Atlantic. On the glaciolacustrine flat plains in the central part of Kaliningrad oblast, where there were no deep depressions, the mire formation process was manifested weakly for a long time. A colder and more humid climate, which is a condition necessary for the raised bog peat accumulation and rapid expansion of bogs to the adjacent forest area, occurred only in the Subatlantic.

Comprehensive Structural Dynamic Analysis of the SSME/AT Fuel Pump First-Stage Turbine Blade

NASA Technical Reports Server (NTRS)

Brown, A. M.

1998-01-01

A detailed structural dynamic analysis of the Pratt & Whitney high-pressure fuel pump first-stage turbine blades has been performed to identify the cause of the tip cracking found in the turbomachinery in November 1997. The analysis was also used to help evaluate potential fixes for the problem. Many of the methods available in structural dynamics were applied, including modal displacement and stress analysis, frequency and transient response to tip loading from the first-stage Blade Outer Gas Seals (BOGS), fourier analysis, and shock spectra analysis of the transient response. The primary findings were that the BOGS tip loading is impulsive in nature, thereby exciting many modes of the blade that exhibit high stress at the tip cracking location. Therefore, a proposed BOGS count change would not help the situation because a clearly identifiable resonance situation does not exist. The recommendations for the resolution of the problem are to maintain the existing BOGS count, eliminate the stress concentration in the blade due to its geometric design, and reduce the applied load on the blade by adding shiplaps in the BOGS.

Summer foods of American widgeon, mallards, and a green-winged teal near Great Slave Lake, N.W.T

USGS Publications Warehouse

Bartonek, J.C.

1972-01-01

Foods found in three species of dabbling ducks collected during summer from bog ponds, and sedge pools in taiga on the north side of Great Slave Lake, Northwest Territories, are described. Animal material in the esophageal contents of 10 adult American Widgeons (Mareca americana) averaged 31 i?? 34 per cent (P<0.05) by volume. A significantly higher percentage of animal material was found in Class I and II widgeon ducklings (66 i?? 22 per cent) than in Class IIIa ducklings and flying juveniles (12 i?? 20 per cent) of this species. Animal material comprised 87 i?? 35 per cent of esophageal contents from five Class II and flying juvenile Mallards (Anas platyrhynchos) and 100 per cent of that from an adult female Green-winged Teal (A. carolinensis).

Grass species influence on plant N uptake - Determination of atmospheric N deposition to a semi-natural peat bog site using a 15N labelling approach

NASA Astrophysics Data System (ADS)

Hurkuck, Miriam; Brümmer, Christian; Spott, Oliver; Flessa, Heinz; Kutsch, Werner L.

2014-05-01

Large areas of natural peat bogs in Northwestern Germany have been converted to arable land and were subjected to draining and peat cutting in the past. The few protected peatland areas remaining are affected by high nitrogen (N) deposition. Our study site - a moderately drained raised bog - is surrounded by highly fertilized agricultural land and livestock production. In this study, we used a 15N pool dilution technique called 'Integrated Total Nitrogen Input' (ITNI) to quantify annual deposition of atmospheric N into biomonitoring pots over a two-year period. Since it considers direct N uptake by plants, it was expected to result in higher N input than conventional methods for determination of N deposition (e.g. micrometeorological approaches, bulk N samplers). Using Lolium multiflorum and Eriophorum vaginatum as monitor plants and low, medium and high levels of fertilization, we aimed to simulate increasing N deposition to planted pots and to allocate airborne N after its uptake by the soil-plant system in aboveground biomass, roots and soil. Increasing N fertilization was positively correlated with biomass production of Eriophorum vaginatum, whereas atmospheric plant N uptake decreased and highest airborne N input of 899.8 ± 67.4 µg N d-1 pot-1 was found for low N fertilization. In contrast, Lolium multiflorum showed a clear dependency of N supply on plant N uptake and was highest (688.7 ± 41.4 µg N d-1 pot-1) for highly fertilized vegetation pots. Our results suggest that grass species respond differently to increasing N input. While crop grasses such as Lolium multiflorum take up N according to N availability, species adopted to nutrient-limited conditions like Eriophorum vaginatum show N saturation effects with increasing N supply. Total airborne N input ranged from about 24 to 66 kg N ha-1 yr-1 dependent on the used indicator plant and the amount of added fertilizer. Parallel determination of atmospheric N deposition using a micrometeorological approach complemented with bulk samplers was about 24 kg N ha-1 yr-1 during both years of experiments and was thus at the lower range of results obtained by the ITNI method. The low 15N recovery rate of about 50 % during some experiments indicated an underestimation of the applied ITNI approach, resulting in a maximum possible N uptake of twice as high as the determined N input. Most likely, the intensive agricultural land management of the surrounding areas leads to this high N deposition into the protected peatland area. As a result, increasing sensitivity of ombrotrophic vegetation with a subsequent change in plant species composition and a decline in bog-specific vegetation cannot be excluded.

Helium extraction and nitrogen removal from LNG boil-off gas

NASA Astrophysics Data System (ADS)

Xiong, L.; Peng, N.; Liu, L.; Gong, L.

2017-02-01

The helium bearing boil off gas (BOG) from liquid natural gas (LNG) storage tank in LNG plant, which has a helium concentration of about 1%, has attracted the attention in China as a new helium source. As the BOG is usually reused by re-condensing to recover methane, it is likely to cause continuous accumulation of nitrogen in the unit, thus a nitrogen removal process must be integrated. This paper describes a conceptional cryogenic separation system aiming at recovering methane, helium and nitrogen from BOG based on cryogenic distillation and condensation process.

From broadscale patterns to fine-scale processes: habitat structure influences genetic differentiation in the pitcher plant midge across multiple spatial scales.

PubMed

Rasic, Gordana; Keyghobadi, Nusha

2012-01-01

The spatial scale at which samples are collected and analysed influences the inferences that can be drawn from landscape genetic studies. We examined genetic structure and its landscape correlates in the pitcher plant midge, Metriocnemus knabi, an inhabitant of the purple pitcher plant, Sarracenia purpurea, across several spatial scales that are naturally delimited by the midge's habitat (leaf, plant, cluster of plants, bog and system of bogs). We analysed 11 microsatellite loci in 710 M. knabi larvae from two systems of bogs in Algonquin Provincial Park (Canada) and tested the hypotheses that variables related to habitat structure are associated with genetic differentiation in this midge. Up to 54% of variation in individual-based genetic distances at several scales was explained by broadscale landscape variables of bog size, pitcher plant density within bogs and connectivity of pitcher plant clusters. Our results indicate that oviposition behaviour of females at fine scales, as inferred from the spatial locations of full-sib larvae, and spatially limited gene flow at broad scales represent the important processes underlying observed genetic patterns in M. knabi. Broadscale landscape features (bog size and plant density) appear to influence oviposition behaviour of midges, which in turn influences the patterns of genetic differentiation observed at both fine and broad scales. Thus, we inferred linkages among genetic patterns, landscape patterns and ecological processes across spatial scales in M. knabi. Our results reinforce the value of exploring such links simultaneously across multiple spatial scales and landscapes when investigating genetic diversity within a species. © 2011 Blackwell Publishing Ltd.

Biogeochemistry of carbon and related major and trace elements in peat bog soils of the middle taiga of Western Siberia (Russia).

NASA Astrophysics Data System (ADS)

Stepanova, V. A.; Mironycheva-Tokareva, N. P.; Pokrovsky, O. S.

2012-04-01

Global climate changes impact the status of wetland ecosystems shifting the balances of the carbon, macro-, and microelements cycles. This study aims to establish the features of accumulation and distribution of major- and trace elements in the organic layer of peat bog soils, belonging to different ecosystems of the oligotrophic bog complex located in the middle taiga of Western Siberia (Khanty-Mansiysk region, Russia). Key areas which are selected for this study include the following bog conjugate elementary ecosystems: higher ryam, lower ryam, ridge-hollow complex, and oligotrophic poor fen as characterized previously [1]. We have sampled various peat types along the entire length of the soil column (every 10 cm down to 3 m). Peat samples were analyzed for a wide range of macro- and microelements using an ICP-MS technique following full acid digestion in a microwave oven. These measurements allowed quantitative estimates of major- and trace elements in the peat deposits within the whole bog complex and individual elementary landscapes. Based on the data obtained, the lateral and radial geochemical structures of the bog landscapes were determined and clarified for the first time for middle taiga of the West Siberian plain. The similar regime of mineral nutrition during the complete bog landscape formation was detected for the peat deposits based on the measurements of some major- and trace elements (Ca, Fe, Mg, etc.). The vertical distribution of some major and some trace elements along the profile of peat column is rather uniform with relatively strong increase in the bottom organic layers. This strongly suggests the similarity of the processes of element accumulation in the peat and relatively weak post depositional redistribution of elements within the peat soil profile. Overall, obtained corroborate the existing view on chemical composition of peats being determined by botanical peat's components (which forms this peat deposit), atmospheric precipitation, position of ecosystems in the landscape (lateral migration) and types of bedrocks [2]. The results allow better understanding of the coupling between biogeochemical cycles of carbon and major and trace elements in peat soils in order to predict the future changes in both concentrations and stocks of chemical elements in the Western Siberia peat bog systems under climate warming.

SPRUCE S1 Bog Vegetation Allometric and Biomass Data: 2010-2011

DOE Data Explorer

Hanson, P. J. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; Brice, D. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; Garten, C. T. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; Hook, L. A. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; Phillips, J. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; Todd, D. E. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.

2012-01-01

This data set reports the results of measurements on sampled aboveground tissues of trees (Picea mariana and Larix laricina), shrubs (Ledum, Chamaedaphne, and Vaccinium), and ground layer vegetation (all species) of the S1 Bog located in areas adjacent to planned experimental study plots. Ground layer vegetation was sampled from both hummocks and hollows, within a 0.25 m2 plot, to evaluate total standing biomass of bog vegetation at or near the peak of annual production. Vegetation was harvested, processed, and measured in July of 2010 and again in June of 2011.

Geochemical characteristics of peat from two raised bogs of Germany

NASA Astrophysics Data System (ADS)

Mezhibor, A. M.

2016-11-01

Peat has a wide range of applications in different spheres of human activity, and this is a reason for a comprehensive study. This research represents the results of an ICP-MS study of moss and peat samples from two raised bogs of Germany. Because of the wide use of sphagnum moss and peat, determining their geochemical characteristics is an important issue. According to the results obtained, we can resume that the moss samples from Germany are rich in Cu, As, Y, Zr, Nb, and REE. The geochemical composition of the bogs reflects the regional environmental features and anthropogenic influence.

Dibasic Ammonium Phosphate Application Enhances Aromatic Compound Concentration in Bog Bilberry Syrup Wine.

PubMed

Wang, Shao-Yang; Li, Yi-Qing; Li, Teng; Yang, Hang-Yu; Ren, Jie; Zhang, Bo-Lin; Zhu, Bao-Qing

2016-12-29

A nitrogen deficiency always causes bog bilberry syrup wine to have a poor sensory feature. This study investigated the effect of nitrogen source addition on volatile compounds during bog bilberry syrup wine fermentation. The syrup was supplemented with 60, 90, 120 or 150 mg/L dibasic ammonium phosphate (DAP) before fermentation. Results showed that an increase of DAP amounts accelerated fermentation rate, increased alcohol content, and decreased sugar level. Total phenol and total flavonoid content were also enhanced with the increase of DAP amounts. A total of 91 volatile compounds were detected in the wine and their concentrations were significantly enhanced with the increase of DAP. Ethyl acetate, isoamyl acetate, phenethyl acetate, ethyl butanoate, ethyl hexanoate, ethyl octanoate, ethyl decanoate, isobutanol, isoamyl alcohol, levo -2,3-butanediol, 2-phenylethanol, meso -2,3-butanediol, isobutyric acid, hexanoic acid, and octanoic acid exhibited a significant increase of their odor activity value (OAV) with the increase of DAP amounts. Bog bilberry syrup wine possessed fruity, fatty, and caramel flavors as its major aroma, whereas a balsamic note was the least present. The increase of DAP amounts significantly improved the global aroma attributes, thereby indicating that DAP supplementation could promote wine fermentation performance and enhance the sensory quality of bog bilberry syrup wine.

Ecology of southeastern shrub bogs (pocosins) and Carolina bays: a community profile

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

Sharitz, R.R.; Gibbons, J.W.

1982-11-01

Shrub bogs of the Southeast occur in areas of poorly developed internal drainage that typically but not always have highly developed organic or peat soils. Pocosins and Carolina bays are types or subclasses of shrub bogs on the coastal plains of the Carolinas and Georgia. They share roughly the same distribution patterns, soil types, floral and faunal species composition and other community attributes, but differ in geological formation. Carolina bays may contain pocosin as well as other communities, but are defined more by their unique elliptical shape and geomorphometry. The pocosin community is largely defined by its vegetation, a combinationmore » of a dense shrub understory and a sparser canopy. The community is part of a complex successional sequence of communities (sedge bogs, savannas, cedar bogs, and bay forests) that may be controlled by such factors as fire, hydroperiod, soil type, and peat depth. Pocosins and Carolina bays harbor a number of animal groups and may be locally important in their ecology. Although few species are endemic to these habitats, they may provide important refuges for a number of species. These communities are simultaneously among the least understood and most rapidly disappearing habitats of the Southeast. Forestry and agricultural clearage are current impacts.« less

Bacterial Abundance and Activity across Sites within Two Northern Wisconsin Sphagnum Bogs.

PubMed

Fisher; Graham; Graham

1998-11-01

Abstract Bacterial abundance, temperature, pH, and dissolved organic carbon (DOC) concentration were compared across surface sites within and between two northern Wisconsin Sphagnum peatlands over the summer seasons in 1995 and 1996. Sites of interest were the Sphagnum mat surface, the water-filled moat (lagg) at the bog margin, and the bog lake littoral zone. Significant differences in both bacterial populations and water chemistry were observed between sites. pH was highest in the lake and lowest in the mat at both bogs; the opposite was true for DOC. Large populations of bacteria were present in surface interstitial water from the mat; abundance in this site was consistently higher than in the moat or lake. Bacterial abundance also increased across sites of increasing DOC concentration and declining pH. Bacterial activities (rates of [3H]leucine incorporation) and growth in dilution cultures (with grazers removed) were also assessed in lake, moat, and mat sites. Results using these measures generally supported the trends observed in abundance, although high rates of [3H]leucine incorporation were recorded in the moat at one of the bogs. Our results indicate that bacterial populations in Sphagnum peatlands are not adversely affected by acidity, and that DOC may be more important than pH in determining bacterial abundance in these environments.

Dendrochronologically dated pine stumps document phase-wise bog expansion at a northwest German site between ca. 6700 and ca. 3400 BC

NASA Astrophysics Data System (ADS)

Maike Achterberg, Inke Elisabeth; Eckstein, Jan; Birkholz, Bernhard; Bauerochse, Andreas; Leuschner, Hanns Hubert

2018-01-01

The investigated northwest German mire site at Totes Moor is densely covered with subfossil pine stumps (Pinus sylvestris L.) from the fen-bog transition. This facilitates the spatio-temporal reconstruction of mire development, which is based on 212 in situ tree stumps in the case study presented here. Six dendrochronologically dated site chronologies together cover 2345 years between 6703 and 3403 BC. The gaps in between are 6 to 550 years long. Additionally, a floating chronology of 309 years, containing 30 trees, was radiocarbon-dated to the beginning of the 7th millennium cal BC. Peat-stratigraphical survey was carried out additionally, and elevations a.s.l. were determined at several locations. Tree dying-off phases, which indicate water level rise at the site, mostly in context of the local fen-bog transition, are evident for ca. 6600-6450, ca. 6350-5750, ca. 5300-4900, ca. 4700-4550, ca. 3900-3850, ca. 3700-3600, ca. 3500-3450 and ca. 3400 BC. The spatial distribution of the dated in situ trees illustrates the phase-wise expansion of raised bog over fen peat at the site. The documented bog expansion pulses likely correspond to climatic wet sifts.

Effects of permafrost aggradation on peat properties as determined from a pan-Arctic synthesis of plant macrofossils

USGS Publications Warehouse

Treat, C.C.; Jones, Miriam C.; Camill, P.; Gallego-Sala, A.; Garneau, M.; Harden, Jennifer W.; Hugelius, G.; Klein, E.S.; Kokfelt, U.; Kuhry, P.; Loisel, Julie; Mathijssen, J.H.; O'Donnell, J.A.; Oksanen, P.O.; Ronkainen, T.M.; Sannel, A.B.K.; Talbot, J. J.; Tarnocal, C.M.; Valiranta, M.

2016-01-01

Permafrost dynamics play an important role in high-latitude peatland carbon balance and are key to understanding the future response of soil carbon stocks. Permafrost aggradation can control the magnitude of the carbon feedback in peatlands through effects on peat properties. We compiled peatland plant macrofossil records for the northern permafrost zone (515 cores from 280 sites) and classified samples by vegetation type and environmental class (fen, bog, tundra and boreal permafrost, and thawed permafrost). We examined differences in peat properties (bulk density, carbon (C), nitrogen (N) and organic matter content, and C/N ratio) and C accumulation rates among vegetation types and environmental classes. Consequences of permafrost aggradation differed between boreal and tundra biomes, including differences in vegetation composition, C/N ratios, and N content. The vegetation composition of tundra permafrost peatlands was similar to permafrost-free fens, while boreal permafrost peatlands more closely resembled permafrost-free bogs. Nitrogen content in boreal permafrost and thawed permafrost peatlands was significantly lower than in permafrost-free bogs despite similar vegetation types (0.9% versus 1.5% N). Median long-term C accumulation rates were higher in fens (23 g C m−2 yr−1) than in permafrost-free bogs (18 g C m−2 yr−1) and were lowest in boreal permafrost peatlands (14 g C m−2 yr−1). The plant macrofossil record demonstrated transitions from fens to bogs to permafrost peatlands, bogs to fens, permafrost aggradation within fens, and permafrost thaw and reaggradation. Using data synthesis, we have identified predominant peatland successional pathways, changes in vegetation type, peat properties, and C accumulation rates associated with permafrost aggradation.

Local Spatial Heterogeneity of Holocene Carbon Accumulation throughout the Peat Profile of an Ombrotrophic Northern Minnesota Bog

DOE PAGES

McFarlane, Karis J.; Hanson, Paul J.; Iversen, Colleen M.; ...

2018-05-30

Here, we evaluated the spatial heterogeneity of historical carbon accumulation rates in a forested, ombrotrophic bog in Minnesota to aid understanding of responses to an ongoing decade-long warming manipulation. Eighteen peat cores indicated that the bog has been accumulating carbon for over 11,000 years, to yield 176±40 kg C m –2 to 225±58 cm of peat depth. Estimated peat basal ages ranged from 5100 to 11,100 cal BP. The long-term apparent rate of carbon accumulation over the entire peat profile was 22±2 kg C m –2yr –1. Plot location within the study area did not affect carbon accumulation rates, butmore » estimated basal ages were younger in profiles from plots closer to the bog lagg and farther from the bog outlet. In addition, carbon accumulation varied considerably over time. Early Holocene net carbon accumulation rates were 30±6 g C m –2yr –1. Around 3300 calendar BP, net carbon accumulation rates dropped to 15±8 g C m –2yr –1until the last century when net accumulation rates increased again to 74±57 g C m –2yr –1. During this period of low accumulation, regional droughts may have lowered the water table, allowing for enhanced aerobic decomposition and making the bog more susceptible to fire. These results suggest that experimental warming treatments, as well as a future warmer climate may reduce net carbon accumulation in peat in this and other southern boreal peatlands. Furthermore, our we caution against historical interpretations extrapolated from one or a few peat cores.« less

Microbial Community Structure and Activity Linked to Contrasting Biogeochemical Gradients in Bog and Fen Environments of the Glacial Lake Agassiz Peatland

PubMed Central

Lin, X.; Green, S.; Tfaily, M. M.; Prakash, O.; Konstantinidis, K. T.; Corbett, J. E.; Chanton, J. P.; Cooper, W. T.

2012-01-01

The abundances, compositions, and activities of microbial communities were investigated at bog and fen sites in the Glacial Lake Agassiz Peatland of northwestern Minnesota. These sites contrast in the reactivity of dissolved organic matter (DOM) and the presence or absence of groundwater inputs. Microbial community composition was characterized using pyrosequencing and clone library construction of phylogenetic marker genes. Microbial distribution patterns were linked to pH, concentrations of dissolved organic carbon and nitrogen, C/N ratios, optical properties of DOM, and activities of laccase and peroxidase enzymes. Both bacterial and archaeal richness and rRNA gene abundance were >2 times higher on average in the fen than in the bog, in agreement with a higher pH, labile DOM content, and enhanced enzyme activities in the fen. Fungi were equivalent to an average of 1.4% of total prokaryotes in gene abundance assayed by quantitative PCR. Results revealed statistically distinct spatial patterns between bacterial and fungal communities. Fungal distribution did not covary with pH and DOM optical properties and was vertically stratified, with a prevalence of Ascomycota and Basidiomycota near the surface and much higher representation of Zygomycota in the subsurface. In contrast, bacterial community composition largely varied between environments, with the bog dominated by Acidobacteria (61% of total sequences), while the Firmicutes (52%) dominated in the fen. Acetoclastic Methanosarcinales showed a much higher relative abundance in the bog, in contrast to the dominance of diverse hydrogenotrophic methanogens in the fen. This is the first quantitative and compositional analysis of three microbial domains in peatlands and demonstrates that the microbial abundance, diversity, and activity parallel with the pronounced differences in environmental variables between bog and fen sites. PMID:22843538

The stable carbon isotope composition of methane produced and emitted from northern peatlands

NASA Astrophysics Data System (ADS)

Hornibrook, Edward R. C.

Stable carbon isotope values, pore water concentration, and flux data for methane (CH4) were compiled for 26 peatlands situated in the northern hemisphere to explore relationships between trophic status and CH4 cycling. Methane produced in ombrotrophic bogs has δ13C values that are significantly more negative than CH4 formed in fens apparently because of poor dissociation of acetic acid or an absence of methanogenic archaea capable of metabolizing acetic acid under low pH conditions. The δ 13C values of CH4 in pore water of ombrotrophic and minerotrophic peatlands exhibit the opposite trend: δ13C(CH4) values become more positive with depth in rain-fed bogs and more negative with depth in fens. The key zone for methanogenesis occurs at shallow depths in both types of peatland and consequently, δ13C values of CH4 emitted from ombrotrophic bogs (-74.9 ± 9.8‰ n = 42) are more negative than from fens (-64.8 ± 4.0‰ n = 38). An abundance of graminoids in fens contributes to more positive δ13C(CH4) values in pore water through (1) release of root exudates which promotes aceticlastic methanogenesis, (2) rhizosphere oxidization of CH4 causing localized enrichment of 13CH4, and (3) preferential export of 12CH4 through aerenchyma, which also enriches pore water in 13CH4. Emissions from blanket bogs and raised bogs should be attributed more negative δ13C(CH4) values relative to fens in isotope-weighted mass balance budgets. Further study is needed of bogs that have an apparently low nutrient status but exhibit a pore water distribution of δ13C(CH4) values similar to fens.

Unveiling exceptional Baltic bog ecohydrology, autogenic succession and climate change during the last 2000 years in CE Europe using replicate cores, multi-proxy data and functional traits of testate amoebae

NASA Astrophysics Data System (ADS)

Gałka, Mariusz; Tobolski, Kazimierz; Lamentowicz, Łukasz; Ersek, Vasile; Jassey, Vincent E. J.; van der Knaap, Willem O.; Lamentowicz, Mariusz

2017-01-01

We present the results of high-resolution, multi-proxy palaeoecological investigations of two parallel peat cores from the Baltic raised bog Mechacz Wielki in NE Poland. We aim to evaluate the role of regional climate and autogenic processes of the raised bog itself in driving the vegetation and hydrology dynamics. Based on partly synchronous changes in Sphagnum communities in the two study cores we suggest that extrinsic factors (climate) played an important role as a driver in mire development during the bog stage (500-2012 CE). Using a testate amoebae transfer function, we found exceptionally stable hydrological conditions during the last 2000 years with a relatively high water table and lack of local fire events that allowed for rapid peat accumulation (2.75 mm/year) in the bog. Further, the strong correlation between pH and community-weighted mean of testate amoeba traits suggests that other variables than water-table depth play a role in driving microbial properties under stable hydrological conditions. There is a difference in hydrological dynamics in bogs between NW and NE Poland until ca 1500 CE, after which the water table reconstructions show more similarities. Our results illustrate how various functional traits relate to different environmental variables in a range of trophic and hydrological scenarios on long time scales. Moreover, our data suggest a common regional climatic forcing in Mechacz Wielki, Gązwa and Kontolanrahka. Though it may still be too early to attempt a regional summary of wetness change in the southern Baltic region, this study is a next step to better understand the long-term peatland palaeohydrology in NE Europe.

Local Spatial Heterogeneity of Holocene Carbon Accumulation throughout the Peat Profile of an Ombrotrophic Northern Minnesota Bog

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

McFarlane, Karis J.; Hanson, Paul J.; Iversen, Colleen M.

Here, we evaluated the spatial heterogeneity of historical carbon accumulation rates in a forested, ombrotrophic bog in Minnesota to aid understanding of responses to an ongoing decade-long warming manipulation. Eighteen peat cores indicated that the bog has been accumulating carbon for over 11,000 years, to yield 176±40 kg C m –2 to 225±58 cm of peat depth. Estimated peat basal ages ranged from 5100 to 11,100 cal BP. The long-term apparent rate of carbon accumulation over the entire peat profile was 22±2 kg C m –2yr –1. Plot location within the study area did not affect carbon accumulation rates, butmore » estimated basal ages were younger in profiles from plots closer to the bog lagg and farther from the bog outlet. In addition, carbon accumulation varied considerably over time. Early Holocene net carbon accumulation rates were 30±6 g C m –2yr –1. Around 3300 calendar BP, net carbon accumulation rates dropped to 15±8 g C m –2yr –1until the last century when net accumulation rates increased again to 74±57 g C m –2yr –1. During this period of low accumulation, regional droughts may have lowered the water table, allowing for enhanced aerobic decomposition and making the bog more susceptible to fire. These results suggest that experimental warming treatments, as well as a future warmer climate may reduce net carbon accumulation in peat in this and other southern boreal peatlands. Furthermore, our we caution against historical interpretations extrapolated from one or a few peat cores.« less

Temperature sensitivity differences with depth and season between carbon, nitrogen, and phosphorus cycling enzyme activities in an ombrotrophic peatland system

NASA Astrophysics Data System (ADS)

Steinweg, J. M.; Kostka, J. E.; Hanson, P. J.; Schadt, C. W.

2017-12-01

Northern peatlands have large amounts of soil organic matter due to reduced decomposition. Breakdown of organic matter is initially mediated by extracellular enzymes, the activity of which may be controlled by temperature, moisture, and substrate availability, all of which vary seasonally throughout the year and with depth. In typical soils the majority of the microbial biomass and decomposition occurs within the top 30cm due to reduced organic matter inputs in the subsurface however peatlands by their very nature contain large amounts of organic matter throughout their depth profile. We hypothesized that potential enzyme activity would be greatest at the surface of the peat due to a larger microbial biomass compared to 40cm and 175cm below the surface and that temperature sensitivity would be greatest at the surface during winter but lowest during the summer due to high temperatures and enzyme efficiency. Peat samples were collected in February, July, and August 2012 from the DOE Spruce and Peatland Responses Under Climatic and Environmental Change project at Marcell Experimental Forest S1 bog. We measured potential activity of hydrolytic enzymes involved in three different nutrient cycles: beta-glucosidase (carbon), leucine amino peptidase (nitrogen), and phosphatase (phosphorus) at 15 temperature points ranging from 3°C to 65°C. Enzyme activity decreased with depth as expected but there was no concurrent change in activation energy (Ea). The reduction in enzyme activity with depth indicates a smaller pool which coincided with a decreased microbial biomass. Differences in enzyme activity with depth also mirrored the changes in peat composition from the acrotelm to the catotelm. Season did play a role in temperature sensitivity with Ea of β-glucosidase and phosphatase being the lowest in August as expected but leucine amino peptidase (a nitrogen acquiring enzyme) Ea was not influenced by season. As temperatures rise, especially in winter months, enzymatic carbon and phosphorus acquisition in the Marcell bog may increase whereas nitrogen acquisition would remain unchanged. The lack of temperature response for leucine amino peptidase has been measured in other systems but may be less of a concern in the Marcell bog due to low microbial biomass and enzymatic activity at depth and relatively low peat C:N ratios.

SPRUCE Shrub-Layer Growth Assessments in S1-Bog Plots and SPRUCE Experimental Plots beginning in 2010

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

Hanson, P.J.; Phillips, J.R.; Brice, D.J.

This data set reports shrub layer growth assessments for the S1-Bog on the Marcell Experimental Forest in Minnesota from 2010 through 2017. Data were obtained by destructively harvesting two 0.25 m2 plots within defined plot areas of the S1-Bog or SPRUCE experimental plots. In 2015, SPRUCE plots 4, 6, 8, 10, 11, 13, 16, 17, 19 and 20 were enclosed in the SPRUCE enclosures. Prior to 2015 all data are for open ambient conditions. In early years a distinct hummock and a hollow sampling square were both collected, but in later years unsampled hollow areas became unavailable due to priormore » sampling or instrument installations. All vegetation material above the Sphagnum surface of the bog was clipped and transferred to plastic storage bags which were then frozen until the samples could be sorted. Sorting was done by species, tissue type (leaves vs. stems) and tissue age (current-year vs. older tissues).« less

Decadal changes in peat carbon accrual rates in bogs in Northern Minnesota

NASA Astrophysics Data System (ADS)

Fissore, C.; Nater, E. A.; McFarlane, K. J.

2017-12-01

Throughout the Holocene, peatland ecosystems have accumulated substantial amounts of carbon (C) and currently store about one third of all soil organic carbon (SOC) worldwide. Large uncertainty still persists on whether peatland ecosystems located in northern latitudes will continue to act as C sinks, or if the effects of global warming will have greater effects on decomposition processes than on net ecosystem production. We investigated decadal C accrual rates of the top 25 cm of peats in three Sphagnum-rich peatlands located in Northern Minnesota (two ombrotrophic bogs and one fen). We used radiocarbon analysis of Sphagnum cellulose and model fitting to determine peat ages, and peat FTIR spectroscopy to determine humification indices and relative decomposition of peat samples with depth. We had the scope to detect whether recent warming has had an effect on peat decomposition and C accumulation rates. Modeled C accumulation rates in the three peatlands during the past five decades ranged between 78 and 107 g C m-2 yr-1 in the top 25 cm analyzed in this study, values that are higher than the 22 to 29 g C m-2 yr-1 obtained for long-term (millennial) accumulations for the entire bog profiles. Peat IR spectra and C:N ratios confirm low levels of decomposition across the bog sites, especially in the uppermost parts of the peat. The fen site showed very limited decomposition across the entire sampled profile. Higher rates of C accumulation, combined with low decomposition rates close to the surface provide a good estimate of net primary productivity. As substrate decomposition progresses over time, net rates of accumulation decrease. Peat decomposition was more pronounced in the lower depths of the sampled cores in the two ombrotrophic bogs than in the fen, likely an effect of larger temporal variation in water table depth in the bogs than in the fen. Some of the variation in C accumulation and decomposition observed in our bogs and fen suggests that future C accumulation rates will also largely depend on the effect of warming on hydrology, rather than temperature alone.

Remediation System Evaluation, Bog Creek Farm Superfund Site

EPA Pesticide Factsheets

The Bog Creek Farm Superfund site is located in Howell Township, Monmouth County, New Jersey onCounty Road 547. The site is bordered by two residences to the west, the north branch of SquankumBrook to the north, and open fields to the south and east.

Can a bog drained for forestry be a stronger carbon sink than a natural bog forest?

NASA Astrophysics Data System (ADS)

Hommeltenberg, J.; Schmid, H. P.; Drösler, M.; Werle, P.

2014-07-01

This study compares the CO2 exchange of a natural bog forest, and of a bog drained for forestry in the pre-Alpine region of southern Germany. The sites are separated by only 10 km, they share the same soil formation history and are exposed to the same climate and weather conditions. In contrast, they differ in land use history: at the Schechenfilz site a natural bog-pine forest (Pinus mugo ssp. rotundata) grows on an undisturbed, about 5 m thick peat layer; at Mooseurach a planted spruce forest (Picea abies) grows on drained and degraded peat (3.4 m). The net ecosystem exchange of CO2 (NEE) at both sites has been investigated for 2 years (July 2010-June 2012), using the eddy covariance technique. Our results indicate that the drained, forested bog at Mooseurach is a much stronger carbon dioxide sink (-130 ± 31 and -300 ± 66 g C m-2 a-1 in the first and second year, respectively) than the natural bog forest at Schechenfilz (-53 ± 28 and -73 ± 38 g C m-2 a-1). The strong net CO2 uptake can be explained by the high gross primary productivity of the 44-year old spruces that over-compensates the two-times stronger ecosystem respiration at the drained site. The larger productivity of the spruces can be clearly attributed to the larger plant area index (PAI) of the spruce site. However, even though current flux measurements indicate strong CO2 uptake of the drained spruce forest, the site is a strong net CO2 source when the whole life-cycle since forest planting is considered. It is important to access this result in terms of the long-term biome balance. To do so, we used historical data to estimate the difference between carbon fixation by the spruces and the carbon loss from the peat due to drainage since forest planting. This rough estimate indicates a strong carbon release of +134 t C ha-1 within the last 44 years. Thus, the spruces would need to grow for another 100 years at about the current rate, to compensate the potential peat loss of the former years. In contrast, the natural bog-pine ecosystem has likely been a small but stable carbon sink for decades, which our results suggest is very robust regarding short-term changes of environmental factors.

Plant component features of forest-bog ecotones of eutrophic paludification in the south of boreal forest zone of West Siberia

NASA Astrophysics Data System (ADS)

Klimova, N. V.; Chernova, N. A.; Pologova, N. N.

2018-03-01

Paludified forests formed in transitional forest-bog zone aren’t studied enough, inspite of its high expected diversity and large areas in the south of boreal forest zone of West Siberia. In this article wet birch (Betula pubescens) forests of forest-bog ecotones of eutrophic paludification are investigated on Vasyugan plain with nutrient-rich calcareous clays as soil-forming rocks. Species diversity and ecocoenotic structure of these phytocoenoses are discussed. They correlated with wetness and nutrient-availability of habitats evaluated with indicator values of plants. The participation of hydrophylous species is increasing as wetness of habitats increasing in the forest-to-bog direction like in mesotrophic paludification series. However the number of species is higher in the phytocoenoses of eutrophic paludification. The share of species required to nutrient availability is also higher, both in number and in abundance. A lot of these species are usual for eutrophic boreal forested swamps with groundwater input and absent in forests of mesotrophic paludification. Accordingly the nutrient-availability of habitats is also higher. All these features we connect with birch to be a forest forming species instead of dark-coniferous and with the influence of nutrient-rich parent rocks, which is evident in forest-bog ecotones of Vasyugan plain gradually decreasing together with peat horizon thickening.

Nutrient availability at Mer Bleue bog measured by PRSTM probes

NASA Astrophysics Data System (ADS)

Wang, M.; Moore, T. R.; Talbot, J.

2015-12-01

Bogs, covering ~0.7 million km2 in Canada, store a large amount of C and N. As nutrient deficient ecosystems, it's critical to examine the nutrient availabilities and seasonal dynamics. We used Plant Root Simulators (PRSTM) at Mer Bleue bog to provide some baseline data on nutrient availability and its variability. In particular, we focused on ammonium, nitrate, phosphate, calcium, magnesium and potassium, iron, sulphate and aluminum. We placed PRS probes at a depth of 5 - 15 cm in pristine plots and plots with long term N, P and K fertilization for 4 weeks and determined the availability of these nutrients, from spring through to fall. Probes were also placed beneath the water table in hummock and hollow microtopography and along a transect including part of the bog which had been drained through the creation of a ditch 80 years ago. The result showed that there was limited available ammonium, nitrate and phosphate in the bog, the seasonal variation of nutrient availabilities probably due to mineralization, an increase in the availability of some nutrients between different water table depths or as a result of drainage, and the relative availability of nutrients compared to the input from fertilization. We suggest that PRS probes could be a useful tool to examine nutrient availability and dynamics in wetlands, with careful consideration of installing condition, for example, proper exposure period, depth relative to water table etc.

What rules GHG-(greenhouse gas)-fluxes in a prealpine bog - management or watertable?

NASA Astrophysics Data System (ADS)

Förster, Christoph; Drösler, Matthias

2010-05-01

Being an important sink of carbon, the small stripe of bogs in the foreland of the Alps plays an important role for the carbon balance of Germany. A big part was drained for peat-use and to get agricultural land in the last centuries. Restoration of these degraded bogs can help to rebuild this function, whereas the watertable is an important co-factor for the amount of mitigation of greenhouse gases (CO2, CH4 and N2O). To estimate GHG-balances gas-flux measurements, using the chamber method developed by Drösler (2005) were done in 2007 and 2008 on a degraded bog-meadow, which was partly rewetted in 1993 and which is still managed in large areas. This mosaic of restored, drained and managed areas showed big differences in their carbon-balances from a high source (~ 500 g CO2-C m-2 a-1) to a moderate sink (~ -200 g CO2-C m-2 a-1). Where the management was stopped in 1993, some Sphagnum-communities developed which helped to turn these areas from moderate sources (47 g CO2-C m-2 a-1) or sinks (-58 g CO2-C m-2 a-1) to permanent sinks with uptakes between (-150 and -250 g CO2-C m-2 a-1). Key words: bog, carbon-balance, greenhouse gases, restoration, watertable

Hatching success and predation of Bog Turtle (Glyptemys muhlenbergii) eggs in New Jersey and Pennsylvania

USGS Publications Warehouse

Zappalorti, Robert T.; Tutterow, Annalee M.; Pittman, Shannon E.; Lovich, Jeffrey E.

2017-01-01

Nest-site selection by most turtles affects the survival of females and their offspring. Although bog turtles (Glyptemys muhlenbergii) do not typically leave their wetlands for nesting, nest-site selection can impact hatching success and hatchling survival. Between 1974 and 2012, we monitored the fates of 258 bog turtle eggs incubated in the field and 91 eggs incubated under laboratory conditions from 11 different bogs, fens, or wetland complexes in New Jersey and Pennsylvania. Laboratory-incubated eggs exhibited the greatest hatching success (81%), but we did not detect a significant difference in hatching success between nests protected with predator excluder cages (43%) and unprotected nests (33%). However, we found significantly lower predation rates in protected nests, suggesting that while predator excluder cages successfully reduced predation, other environmental factors persisted to reduce egg survival in the field. Natural hatching success was potentially reduced by poor weather conditions, which may have resulted in embryo developmental problems, dehydration, or embryos drowning in the egg. Our results suggest that egg depredation, coupled with embryo developmental problems and infertility, are limiting factors to hatching success in our study populations. Using predator excluder cages to protect bog turtle eggs in the field, or incubating eggs in the laboratory and releasing hatchlings at original nesting areas, may be an effective conservation tool for recovering populations of this federally threatened species.

Contrasting approaches to determine the impact of permafrost thaw on C cycling in northern peatlands

NASA Astrophysics Data System (ADS)

Heffernan, L.; Estop Aragones, C.; Blodau, C.; Olefeldt, D.

2016-12-01

Northern peatlands are a globally significant pool of terrestrial carbon (C) and have acted as a major C sink since the last deglaciation. The peatland complexes found in western Canada are a mosaic of peat plateaus underlain by permafrost interspersed with permafrost free thermokarst bogs. Recent climate change has led to increased rates of thermokarst bog expansion due to permafrost thaw. In order to understand whether permafrost thaw causes net C loss or uptake, we studied both the variation in C stocks and of surface greenhouse gas fluxes along a pair of thermokarst chronosequences located in thick (>6 m) peatlands in the discontinuous permafrost zone of western Canada. Each zone of a chronosequence is characterized by permafrost conditions, including a zone where permafrost is still present (peat plateau), a zone of recent thermokarst development (dominated by Sphagnum riparium and sedges), and a mature thermokarst zone (dominated by Sphagnum fuscum and woody shrubs) where permafrost thaw occurred >50 years ago. Each zone has distinct hydrological conditions, with the recent thermokarst being much wetter. Increased wetness causes increased heat conduction and average July to November soil temperatures at 50, 100, and 200 cm were 1.6, 2.2, and 1.7 °C warmer, respectively, in the recent than in the mature thermokarst zone. This difference likely increases respiration rates at depth substantially. Our study aims to reconcile findings from other sites where investigations of C stock and greenhouse gas emissions have yielded disparate conclusions. By combining C stocks and C emissions along a thaw chronosequence, and highlighting the differences in C cycling between recently and older thawed thermokarst features, this current work aims to reconcile these contrasting views.

Effects of experimental nitrogen deposition on peatland carbon pools and fluxes: a modeling analysis

NASA Astrophysics Data System (ADS)

Wu, Y.; Blodau, C.; Moore, T. R.; Bubier, J. L.; Juutinen, S.; Larmola, T.

2014-07-01

Nitrogen (N) pollution of peatlands alters their carbon (C) balances, yet long-term effects and controls are poorly understood. We applied the model PEATBOG to analyze impacts of long-term nitrogen (N) fertilization on C cycling in an ombrotrophic bog. Simulations of summer gross ecosystem production (GEP), ecosystem respiration (ER) and net ecosystem exchange (NEE) were evaluated against 8 years of observations and extrapolated for 80 years to identify potential effects of N fertilization and factors influencing model behavior. The model successfully simulated moss decline and raised GEP, ER and NEE on fertilized plots. GEP was systematically overestimated in the model compared to the field data due to high tolerance of Sphagnum to N deposition in the model. Model performance regarding the 8 year response of GEP and NEE to N was improved by introducing an N content threshold shifting the response of photosynthesis capacity to N content in shrubs and graminoids from positive to negative at high N contents. Such changes also eliminated the competitive advantages of vascular species and led to resilience of mosses in the long-term. Regardless of the large changes of C fluxes over the short-term, the simulated GEP, ER and NEE after 80 years depended on whether a graminoid- or shrub-dominated system evolved. When the peatland remained shrub-Sphagnum dominated, it shifted to a C source after only 10 years of fertilization at 6.4 g N m-2 yr-1, whereas this was not the case when it became graminoid-dominated. The modeling results thus highlight the importance of ecosystem adaptation and reaction of plant functional types to N deposition, when predicting the future C balance of N-polluted cool temperate bogs.

Reflections on Doing Geography: Learning Observations from the Fourth Grade

ERIC Educational Resources Information Center

Delahunty, Tina

2010-01-01

The Nature Conservancy's (TNC) Orchard Bog site in Shady Valley, Tennessee, is a unique Appalachian mountain bog that provides many opportunities for student exploration. A biogeographer, a field technician, two biologists, and a historian combined their expertise to teach 100 fourth graders how historians and scientists learn about past…

A geospatial model to quantify mean thickness of peat in cranberry bogs

USDA-ARS?s Scientific Manuscript database

Commercial cranberry (Vaccinium macrocarpon Ait.) is cultivated on peatlands, which consist of sedimentary deposits of peat capped by a 0.3-1 m of artificial sand. Despite distinct soil layering, a general paucity of information exists on the physical properties of cranberry bogs. Field measurements...

A geospatial model to quantify mean thickness of peat in cranberry bogs

USDA-ARS?s Scientific Manuscript database

Commercial cranberry (Vaccinium macrocarpon Ait.) is cultivated on peatlands, which consist of sedimentary deposits of peat capped by a 0.3-1 m of artificial sand. Despite distinct soil layering, a general paucity of information exists on the physical properties of cranberry bogs. Field measurement...

SPRUCE S1 Bog Pretreatment Fungal Hyphae Carbon and Nitrogen Concentrations and Stable Isotope Composition from In-growth Cores, 2013-2014

DOE Data Explorer

Hofmockel, K. S. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; Chen, J. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; Hobbie, E. A. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.

2014-02-01

This data set reports fungal hyphal carbon and nitrogen concentrations and δ13C, and δ15N data for samples obtained from in-growth cores in the S1 Bog. Hyphae were collected using 40 μm in-growth bags (10 cm × 10 cm) filled with sterile sand. Bags were incubated in the field in paired hummock and hollows at six locations in the bog. In hummocks, bags were inserted at +10 to 0 cm above the adjacent hollow and in both locations from 0 to -10 cm and -10 to -20 cm below the hollow surface

Chromobacterium sphagni sp. nov., an insecticidal bacterium isolated from Sphagnum bogs

USDA-ARS?s Scientific Manuscript database

Sixteen isolates of Gram-negative, motile, violet-pigmented bacteria were isolated from Sphagnum bogs in West Virginia and Maine, USA. 16S rDNA sequences and fatty acid analysis (FAME) revealed a high degree of relatedness among the isolates, and genomic sequencing of two isolates, IIBBL 14B-1 and I...

Evapotranspiration from two peatland watersheds

Treesearch

Roger R. Bay

1968-01-01

Measurements of precipitation, runoff, and bog water table levels have provided data for the calculation of evapotranspiration from two forested peatland watersheds near Grand Rapids, Minnesota (ca. 47? 32'N, 93? 28'W). Continuous hydrologie records were collected on one experimental bog for 6 years (1961-1966) and on the other for the past 2 years (1965-1966...

Methane fluxes during the cold season: distribution and mass transfer in the snow cover of bogs

NASA Astrophysics Data System (ADS)

Smagin, A. V.; Shnyrev, N. A.

2015-08-01

Fluxes and profile distribution of methane in the snow cover and different landscape elements of an oligotrophic West-Siberian bog (Mukhrino Research Station, Khanty-Mansiisk autonomous district) have been studied during a cold season. Simple models have been proposed for the description of methane distribution in the inert snow layer, which combine the transport of the gas and a source of constant intensity on the soil surface. The formation rates of stationary methane profiles in the snow cover have been estimated (characteristic time of 24 h). Theoretical equations have been derived for the calculation of small emission fluxes from bogs to the atmosphere on the basis of the stationary profile distribution parameters, the snow porosity, and the effective methane diffusion coefficient in the snow layer. The calculated values of methane emission significantly (by 2-3 to several tens of times) have exceeded the values measured under field conditions by the closed chamber method (0.008-0.25 mg C/(m2 h)), which indicates the possibility of underestimating the contribution of the cold period to the annual emission cycle of bog methane.

Nest-site characteristics of Glyptemys muhlenbergii (Bog Turtle) in New Jersey and Pennsylvania

USGS Publications Warehouse

Zappalorti, Robert T.; Lovich, Jeffrey E.; Farrell, Ray F.; Torocco, Michael E.

2015-01-01

Nest-site selection can affect both the survival and fitness of female turtles and their offspring. In many turtle species, the nest environment determines the thermal regime during incubation, length of incubation period, sex ratio of the hatchlings, and exposure to predators and other forms of mortality for both mothers and their offspring. Between 1974 and 2012, we collected detailed data on habitat variables at 66 Glyptemys muhlenbergii (Bog Turtle) nests in 9 different bogs, fens, and wetland complexes in New Jersey and Pennsylvania. The nests had a mean elevation above the substrate of 8.2 cm, and many were shallow and located in raised tussocks of grass or sedges. Females covered most nests, but we also observed partially or completely uncovered eggs. Some females deposited eggs in communal nests; we found 4 nests with 2 separate clutches, and 2 nests with 3 clutches. Principal component analysis confirmed the importance of cover and vegetation to nest-site selection in this species. Availability of open, shade-free, wet nesting areas is an important habitat requirement for Bog Turtles.

Relative importance of local habitat complexity and regional factors for assemblages of oribatid mites (Acari: Oribatida) in Sphagnum peat bogs.

PubMed

Minor, M A; Ermilov, S G; Philippov, D A; Prokin, A A

2016-11-01

We investigated communities of oribatid mites in five peat bogs in the north-west of the East European plain. We aimed to determine the extent to which geographic factors (latitude, separation distance), local environment (Sphagnum moss species, ground water level, biogeochemistry) and local habitat complexity (diversity of vascular plants and bryophytes in the surrounding plant community) influence diversity and community composition of Oribatida. There was a significant north-to-south increase in Oribatida abundance. In the variance partitioning, spatial factors explained 33.1 % of variability in abundance across samples; none of the environmental factors were significant. Across all bogs, Oribatida species richness and community composition were similar in Sphagnum rubellum and Sphagnum magellanicum, but significantly different and less diverse in Sphagnum cuspidatum. Sphagnum microhabitat explained 52.2 % of variability in Oribatida species richness, whereas spatial variables explained only 8.7 %. There was no distance decay in community similarity between bogs with increased geographical distance. The environmental variables explained 34.9 % of the variance in community structure, with vascular plants diversity, bryophytes diversity, and ground water level all contributing significantly; spatial variables explained 15.1 % of the total variance. Overall, only 50 % of the Oribatida community variance was explained by the spatial structure and environmental variables. We discuss relative importance of spatial and local environmental factors, and make general inferences about the formation of fauna in Sphagnum bogs.

Lateral expansion and carbon exchange of a boreal peatland in Finland resulting in 7000 years of positive radiative forcing

NASA Astrophysics Data System (ADS)

Mathijssen, Paul J. H.; Kähkölä, Noora; Tuovinen, Juha-Pekka; Lohila, Annalea; Minkkinen, Kari; Laurila, Tuomas; Väliranta, Minna

2017-03-01

Data on past peatland growth patterns, vegetation development, and carbon (C) dynamics during the various Holocene climate phases may help us to understand possible future climate-peatland feedback mechanisms. In this study, we analyzed and radiocarbon dated several peat cores from Kalevansuo, a drained bog in southern Finland. We investigated peatland succession and C dynamics throughout the Holocene. These data were used to reconstruct the long-term atmospheric radiative forcing, i.e., climate impact of the peatland since initiation. Kalevansuo peat records revealed a general development from fen to bog, typical for the southern boreal zone, but the timing of ombrotrophication varied in different parts of the peatland. Peat accumulation patterns and lateral expansion through paludification were influenced by fires and climate conditions. Long-term C accumulation rates were overall lower than the average values found from literature. We suggest the low accumulation rates are due to repeated burning of the peat surface. Drainage for forestry resulted in a nearly complete replacement of typical bog mosses by forest species within 40 years after drainage. The radiative forcing reconstruction suggested positive values (warming) for the first 7000 years following initiation. The change from positive to negative forcing was triggered by an expansion of bog vegetation cover and later by drainage. The strong relationship between peatland area and peat type with radiative forcing suggests a possible feedback for future changing climate, as high-latitude peatlands may experience prominent regime shifts, such as fen to bog transitions.

Purple Pitcher Plant (Sarracenia rosea) Dieback and Partial Community Disassembly following Experimental Storm Surge in a Coastal Pitcher Plant Bog

PubMed Central

Abbott, Matthew J.; Battaglia, Loretta L.

2015-01-01

Sea-level rise and frequent intense hurricanes associated with climate change will result in recurrent flooding of inland systems such as Gulf Coastal pitcher plant bogs by storm surges. These surges can transport salt water and sediment to freshwater bogs, greatly affecting their biological integrity. Purple pitcher plants (Sarracenia rosea) are Gulf Coast pitcher plant bog inhabitants that could be at a disadvantage under this scenario because their pitcher morphology may leave them prone to collection of saline water and sediment after a surge. We investigated the effects of storm surge water salinity and sediment type on S. rosea vitality, plant community structure, and bog soil-water conductivity. Plots (containing ≥1 ramet of S. rosea) were experimentally flooded with fresh or saline water crossed with one of three sediment types (local, foreign, or no sediment). There were no treatment effects on soil-water conductivity; nevertheless, direct exposure to saline water resulted in significantly lower S. rosea cover until the following season when a prescribed fire and regional drought contributed to the decline of all the S. rosea to near zero percent cover. There were also significant differences in plant community structure between treatments over time, reflecting how numerous species increased in abundance and a few species decreased in abundance. However, in contrast to S. rosea, most of the other species in the community appeared resilient to the effects of storm surge. Thus, although the community may be somewhat affected by storm surge, those few species that are particularly sensitive to the storm surge disturbance will likely drop out of the community and be replaced by more resilient species. Depending on the longevity of these biological legacies, Gulf Coastal pitcher plant bogs may be incapable of fully recovering if they become exposed to storm surge more frequently due to climate change. PMID:25874369

Purple pitcher plant (Sarracenia rosea) Dieback and partial community disassembly following experimental storm surge in a coastal pitcher plant bog.

PubMed

Abbott, Matthew J; Battaglia, Loretta L

2015-01-01

Sea-level rise and frequent intense hurricanes associated with climate change will result in recurrent flooding of inland systems such as Gulf Coastal pitcher plant bogs by storm surges. These surges can transport salt water and sediment to freshwater bogs, greatly affecting their biological integrity. Purple pitcher plants (Sarracenia rosea) are Gulf Coast pitcher plant bog inhabitants that could be at a disadvantage under this scenario because their pitcher morphology may leave them prone to collection of saline water and sediment after a surge. We investigated the effects of storm surge water salinity and sediment type on S. rosea vitality, plant community structure, and bog soil-water conductivity. Plots (containing ≥1 ramet of S. rosea) were experimentally flooded with fresh or saline water crossed with one of three sediment types (local, foreign, or no sediment). There were no treatment effects on soil-water conductivity; nevertheless, direct exposure to saline water resulted in significantly lower S. rosea cover until the following season when a prescribed fire and regional drought contributed to the decline of all the S. rosea to near zero percent cover. There were also significant differences in plant community structure between treatments over time, reflecting how numerous species increased in abundance and a few species decreased in abundance. However, in contrast to S. rosea, most of the other species in the community appeared resilient to the effects of storm surge. Thus, although the community may be somewhat affected by storm surge, those few species that are particularly sensitive to the storm surge disturbance will likely drop out of the community and be replaced by more resilient species. Depending on the longevity of these biological legacies, Gulf Coastal pitcher plant bogs may be incapable of fully recovering if they become exposed to storm surge more frequently due to climate change.

Geochemical and mineralogical composition of bog iron ore as a resource for prehistoric iron production - A case study of the Widawa catchment area in Eastern Silesia, Poland

NASA Astrophysics Data System (ADS)

Thelemann, Michael; Bebermeier, Wiebke; Hoelzmann, Philipp

2016-04-01

Spreading from the Near East in the declining Bronze Age from the 2nd millennium BCE onwards, the technique of iron smelting reached Eastern Silesia, Poland, in approximately the 2nd century BCE (pre-Roman Iron Age). At this time the region of the Widawa catchment area was inhabited by the Przeworsk culture. While the older moraine landscape of the study area lacks ores from geological rock formations, bog iron ores were relatively widespread and, due to their comparatively easy accessibility, were commonly exploited for early iron production. In this poster the mineralogical and elemental composition of local bog iron ore deposits and iron slag finds, as a by-product of the smelting process, are investigated. The crystalline mineralogical composition of local bog iron ores is dominated by quartz (SiO2) and goethite (α FeO(OH)), in contrast to slag samples in which fayalite (Fe2SiO4), wüstite (FeO) and quartz, with traces of goethite, represent the main minerals. Ores and slags are both characterized by notable hematite (Fe2O3), magnetite (Fe3O4) and maghemite (γ-Fe2O3) contents. Analyzed bog iron ore samples show iron contents of up to 64.9 mass% Fe2O3 (45.4 mass% Fe), whereas the iron contents of bloomery slags vary between 48.7 and 72.0 mass% FeO (37.9 and 56.0 mass% Fe). A principal component analysis of the element contents, which were quantified by portable energy-dispersive X-ray fluorescence spectrometry (p-ED-XRF), indicates local variations in the elemental composition. Our results show that bog iron ores are relatively widely distributed with spatially varying iron contents along the Widawa floodplain but present-day formation conditions (e.g. different ground-water levels) are negatively affected by modern land-use practices, such as agriculture and melioration measures.

Accelerated rates of in situ microbial activity after permafrost collapse estimated from a porewater isotope model

NASA Astrophysics Data System (ADS)

Waldrop, M. P.; Neumann, R. B.; Jones, M.; Manies, K.; Mcfarland, J. W.; Blazewicz, S.; Turetsky, M. R.

2016-12-01

Permafrost thaw is expected to become widespread in interior Alaska over the coming century, resulting in increased CO2 and CH4 fluxes from soils and a positive feedback to global warming. However much of our understanding of the microbial response to thaw is predicated on simple laboratory incubations that preclude the multitude of interactions occurring in soils under field situations. Here, we utilize a time series of 13CO2 and 13CH4 measured in porewater collected from thermokarst bogs of different ages to estimate in-situ reaction rates of microbial respiration, methanogenesis from acetate, methanogenesis from CO2, homoacetogenesis, and methane oxidation from porewater concentrations and 13CO2 and 13CH4. We utilized this modeling technique to test the hypothesis that microbial activities are stimulated soon after permafrost thaw and this effect declines over time. Our field site is a chronosequence of thermokarst bogs at the Alaska Peatland Experiment (APEX) in interior AK where we have observed significant losses of peatland carbon since permafrost collapse over the last half century. Concentrations of dissolved CO2 and CH4 in porewater increased with depth, and were higher in the youngest bog compared to the older bogs. With increasing depth 13CH4 became more depleted while 13CO2 became more enriched. Preliminary modeling results, based upon these porewater gas concentrations and isotope values, indicate that microbial activities are higher in the youngest bogs compared to the older bogs, supporting the hypothesis that accelerated rates of microbial activities in young thermokarst features are responsible for high rates of C losses from these systems. Additionally, model results will be compared to variation in the abundance of methanogens, methane oxidizers, and acetogens as well as process rates measured in lab incubations, providing insights into the mechanisms responsible for these losses.

Insight into the Structure of Light Harvesting Complex II and its Stabilization in Detergent Solution

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

Cardoso, Mateus B; Smolensky, Dmitriy; Heller, William T

2009-01-01

The structure of spinach light-harvesting complex II (LHC II), stabilized in a solution of the detergent n-octyl-{beta}-d-glucoside (BOG), was investigated by small-angle neutron scattering (SANS). Physicochemical characterization of the isolated complex indicated that it was pure (>95%) and also in its native trimeric state. SANS with contrast variation was used to investigate the properties of the protein-detergent complex at three different H{sub 2}O/D{sub 2}O contrast match points, enabling the scattering properties of the protein and detergent to be investigated independently. The topological shape of LHC II, determined using ab initio shape restoration methods from the SANS data at the contrastmore » match point of BOG, was consistent with the X-ray crystallographic structure of LHC II (Liu et al. Nature 2004 428, 287-292). The interactions of the protein and detergent were investigated at the contrast match point for the protein and also in 100% D{sub 2}O. The data suggested that BOG micelle structure was altered by its interaction with LHC II, but large aggregate structures were not formed. Indirect Fourier transform analysis of the LHC II/BOG scattering curves showed that the increase in the maximum dimension of the protein-detergent complex was consistent with the presence of a monolayer of detergent surrounding the protein. A model of the LHC II/BOG complex was generated to interpret the measurements made in 100% D{sub 2}O. This model adequately reproduced the overall size of the LHC II/BOG complex, but demonstrated that the detergent does not have a highly regular shape that surrounds the hydrophobic periphery of LHC II. In addition to demonstrating that natively structured LHC II can be produced for functional characterization and for use in artificial solar energy applications, the analysis and modeling approaches described here can be used for characterizing detergent-associated {alpha}-helical transmembrane proteins.« less

Elevated Nitrogen Deposition Enhances the Net CO2 Sink Strength in Alberta Bogs along a Post-fire Chronosequence

NASA Astrophysics Data System (ADS)

Wieder, R. K.; Vile, M. A.; Albright, C. M.; Scott, K. D.

2014-12-01

About 30% of the landscape of northern Alberta, Canada is occupied by peatlands, which persist at the low end range of both mean annual precipitation (<500 mm/yr) and mean annual atmospheric nitrogen (N) deposition (< 1 kg/ha/yr) across which peatlands are found globally. Ombrotrophic bogs in this region function as a net sink for atmospheric CO2 of over 75 g/m2/yr, taking into consideration changes in CO2 sink strength as a function of time since fire. In addition to fire, a new disturbance is emerging in the Athabasca Oil Sands Region (AOSR) of northern Alberta, where development of the oil sands resource has increased atmospheric N deposition to as much as 2.5 kg/ha/yr. To examine the effects of elevated N deposition on bog C cycling, we experimentally applied N (as NH4NO3 solutions) to replicated plots at levels equivalent to 0 (water added with no N), 10, and 20 kg/ha/yr, and controls (no waher, no N added) at five bog sites, aged at 2, 12, 32, 73, and 113 years since fire in 2013 (6 plots per N treatment per site). Understory net ecosystem exchange of CO2 (NEE) was measured repeatedly throughout the 2013 and 2014 growing season (and in 2011 and 2012 at the most recently burned site) using the closed chamber approach. Using a rectangular hyperbola equation to characterize NEE as a function of photosynthetically active radiation (PAR) and near-surface air temperature (T), monthly and annual NEE was estimated based on hourly measurements of PAR and T at each site. Across all sites, a general pattern emerged that N additions enhanced the net CO2 sink strength of the bogs, with no effect on ecosystem respiration. Net primary production of Sphagnum fuscum, the dominant peat-forming moss, was not affected by N addition, suggesting that the overall response of NEE to N addition is the result of enhanced growth of ericaceous shrubs. These findings suggest that while elevated N deposition in the AOSR may enhance the strength of the overall CO2 sink of bogs in the short term, in the longer term, increased shrub growth has the potential to shade Sphagnum mosses, compromising the future bog CO2sink strength across the region.

Tracing of ca 800 yr old mining activity in peat bog using Pb elemental concentrations and isotope compositions.

NASA Astrophysics Data System (ADS)

Baron, S.; Carignan, J.; Ploquin, A.

2003-04-01

Sixty sites of slags have been documented on the Mont-Lozère in southern France. The petrographic analysis shows that slags are metallurgical wastes (800 to 850 yr BP) which certainly result from smelting activity for lead and silver extraction (Ploquin et al., 2001). The aims of this study are: 1) to trace the source of Pb ores which supplied the smelting sites, by using the Pb isotopic composition of several surrounding Pb deposits, 2) to evaluate the actual pollution caused by these slags, by using elemental and isotopic compositions of soils, water and vegetation, and 3) to document the pollution history of the region, by using elemental and isotopic compositions of peat bog cores collected in the neighbourhood of the historical smelting sites. The lead isotopic composition of galena collected in most surrounding ores is very similar to that of different slag samples. On the other hand, the high precision of the results allowed us to select the mineralised areas which were probably the ore sources. The Pb isotopic composition of slags is even more homogeneous: 208/206 Pb: 2.092±0.002; 206/207 Pb: 1.179±0.001; 208/204 Pb: 38.663±0.025; 207/204 Pb: 15.665±0.006; 206/204 Pb: 18.476±0.023, and will allow source tracing in the environment. The "Narses Mortes" peat bog, around which two smelting sites have been reported, is strongly minerotrophic and contains 8 to 60% ash. A 1.40 m core have been retrieved and divided into 58 individual samples. Minerotrophic peat bog records both atmospheric deposition, soils leaching and the grounwater influence. The measured metal concentrations are normalised to Al contents of peat bog samples and the metal/Al ratios are compared to that of the Mont-Lozère granite: relative excess in metal concentrations are found in peat bog samples. An increasing excess of most metals (Pb, Zn, Cd...) was measured for surface samples, from 55 cm depth to the top of the core (23 cm depth). This profil might be attributed to atmospheric input during the last centuries. Pb and As alone are also enriched in some deeper samples (between 120--90 cm depth). At the moment, no sedimentation rates are available for this section of the peat bog. However, according to palynological data (de Beaulieu, in progress), the bottom of the core might be as old as 5000 years BP. This would place the medieval activities at the base of the surface metal enrichment (˜55 cm depth), having no large effect in Pb concentrations measured in peat bog. The older Pb-As enrichment remain enigmatic and may correspond to earlier anthropogenic activities (2000--2500 BP), a period for which very few traces of metallurgical activities are found in Occidental Europe. 14C dating and Pb isotope works are going on peat bog samples trying to discriminate metals sources.

Geohydrology of the cross-Florida barge canal area, with special reference to the Ocala vicinity

USGS Publications Warehouse

Faulkner, Glen L.

1973-01-01

The Cross-Florida Barge Canal route commences at Palatka on the St. Johns River, about 75 miles upstream from the Atlantic Ocean, and extends 110 miles southwestward across Peninsular Florida into deep water in the Gulf of Mexico near Yankeetown. The canal will be equipped with five locks, each 600 feet long and 84 feet wide, and the channel will be a minimum of 12 feet deep and 150 feet wide. From near Ocala northeastward, the canal channel will replace much of the natural channel of the Oklawaha River, and will be excavated into beds of the so-called shallow sand aquifer of Miocene age and younger, which overlies limestone of the Floridan aquifer. Westward from Ocala, most of the canal will be excavated below the potentiometric surface into limestone and dolomite of the Floridan aquifer. Water levels of Rodman, Eureka, and Inglis Pools will be controlled by dams and spillways with the limited exchange of water between the pools and the aquifers. The water levels in the Summit Pools will fluctuate with the natural changes in the ground-water level of the Floridan aquifer, although the stage of the pool will be controlled partly by the stage held in the Eureka Pool. A dynamic inflow-outflow relationship will exist between the Summit Pool and the Floridan aquifer. The Floridan aquifer in the canal area is 1,000 to 1,200 feet thick and consists of limestone and dolomite of middle Eocene Miocene age, including from older to younger, the Lake City, Avon Park, and Ocala limestones plus permeable sandy, dolomitic limestone in the lower part of the Hawthorn Formation. It is possible that most of the flow to the two major springs in the area occurs in the upper 100 feet or so of the aquifer in the Ocala Limestone. The aquifer is underlain by the Oldsmar limestone of early Eocene age and is overlain by sand, clayey sand, clay and shell beds of Miocene through Holocene age, in thickness from a few feet to 300 feet. The permeable beds overlying the Floridan aquifer constitute the shallow aquifer, while the poorly permeable ones act as confining beds where the Floridan aquifer is under artesian conditions. A north-south line drawn separating the head of Silver Springs on the west from the Oklawaha River on the east marks the approximate western limit of a continuous blanket of materials of Miocene-Pliocene(?) age covering the rocks of the Floridan aquifer. East of the line, much of the aquifer is under artesian conditions, particularly in the Oklawaha River valley, although in some areas east of the valley, direct recharge through thick permeable Miocene-Pliocene(?) sands occurs. West of the line, only scattered remnants of a once continuous Miocene-Pliocene(?) cover remain. Lack of the cover is a result of erosion on the crest and flank of the Ocala Uplift, a broad northwest-southeast trending anticlinal upwarp, the axis of which is crossed by the canal route in the Dunnellon area. Over most of this area the Floridan aquifer is unconfined and receives direct recharge through a cover of a few tens of feet of sand and clayey sand of Quaternary age. Tensional stresses during the structural evolution of the Ocala Uplift produced an intersecting system of fractures and normal faults in rocks of the Floridan aquifer. The fractures and faults are important controls for orientation of solution channels and, therefore, for development of ground-water circulation patterns. When the system surface streams, which once drained the Barge Canal area, eroded the poorly permeable Miocene-Pliocene(?) cover from the flanks of the Ocala Uplift, surface runoff was reduced and precipitation began to directly infiltrate the underlying limestones. Now only principal streams remain, such as the Oklawaha and Withlacoochee Rivers and a few short tributaries, while one of the most highly developed subsurface drainage systems in the world has evolved in cavernous limestone of the Floridan aquifer. Two of the larger freshwater springs in the world now

Geohydrology of the Cross-Florida Barge Canal area, with special reference to the Ocala vicinity

USGS Publications Warehouse

Faulkner, Glen L.

1970-01-01

The Cross-Florida Barge Canal route commences at Palatka on the St. Johns River, about 75 miles upstream from the Atlantic Ocean, and extends 110 miles southwestward across Peninsular Florida into deep water in the Gulf of Mexico near Yankeetown. The canal will be equipped with five locks, each 600 feet long and 84 feet wide, and the channel will be a minimum of 12 feet deep and 150 feet wide. From near Ocala northeastward, the canal channel will replace much of the natural channel of the Oklawaha River, and will be excavated into beds of the so-called shallow sand aquifer of Miocene and younger age, which overlies limestone of the Floridan aquifer. Westward from Ocala most of the canal will be excavated below the potentiometric surface into limestone and dolomite of the Floridan aquifer. Water levels of Rodman, Eureka, and Inglis Pools will be controlled by dams and spillways with limited exchange of water between the pools and the aquifers. The water levels in the Summit Pool will fluctuate with the natural changes in the ground-water level of the Floridan aquifer, although the stage of the pool will be partially controlled by the stage held in the Eureka Pool. A dynamic inflow-outflow relationship will exist between the Sun, nit Pool and the Floridan aquifer. The Floridan aquifer in the canal area is 1,000 to 1,200 feet thick and consists of limestone and dolomite of middle Eocene to Miocene age, including, from older to younger the Lake City, Avon Park and Ocala limestones plus permeable sandy, dolomitic limestone in the lower part of the Hawthorn Formation. It is possible that most of the flow to the two major springs in the area occurs in the upper 100 feet or so of the aquifer in the Ocala Limestone. The aquifer is underlain by the Oldsmar Limestone of early Eocene age and is overlain by sand, clayey sand, clay and shell beds of Miocene through Holocene age, ranging from a few feet to two or three hundred feet thick. The permeable beds overlying the Floridan aquifer constitute the shallow aquifer, while the poorly permeable ones act as confining beds where the Floridan aquifer is under artesian conditions. A north-south line drawn separating the head of Silver Springs on the west from the Oklawaha River on the east marks the approximate westward limit of a continuous blanket of Miocene-Pliocene(?) age materials covering the rocks of the Floridan aquifer. East of the line much of the aquifer is under artesian conditions, particularly in the Oklawaha River valley, although in some areas east of the valley direct recharge through thick permeable Miocene-Pliocene(?) sands occurs. West of the line, only scattered remnants of a once continuous Miocene-Pliocene(?) cover remains. Lack of the cover is a result of erosion on the crest and flanks of the Ocala Uplift, a broad northwest-southeast trending anticlinal upwarp, the axis of which is crossed by the canal route in the Dunnellon area. Over most of this area the Floridan aquifer is unconfined, and receives direct recharge through a cover of a few tens of feet of sand and clayey sand of Quaternary age. Tensional stresses during the structural evolution of the Ocala Uplift produced an intersecting system of fractures and normal faults in rocks of the Florida Aquifer. The fractures and faults are important controls for orientation of solution channels, and, therefore, for development of ground-water circulation patterns. When the system of surface streams which once drained the Barge Canal area eroded the poorly permeable Miocene-Pliocene(?) cover from the flanks of the Ocala Uplift, surface runoff was reduced and precipitation began to directly infiltrate the underlying limestones. Now only principal rivers, such as the Oklawaha and Withlacoochee Rivers, and a few short tributaries remain, while one of the most highly developed subsurface drainage systems in the world has evolved in the cavernous limestones of the Floridan aquifer. Two of the larger fresh water spr

Ca isotopes reveal weak control of tectonic uplift on long-term climate change

NASA Astrophysics Data System (ADS)

Moore, J.; Jacobson, A. D.; Holmden, C. E.; Craw, D.

2010-12-01

Ca-Mg silicate weathering consumes atmospheric CO2 over geological timescales (≥106 yr) whereas carbonate weathering has no effect. High Ca fluxes from active orogens have been used to argue that mountain uplift is a disproportionately large CO2 sink. To test this hypothesis, it is essential to determine proportions of Ca from silicate versus carbonate weathering. High precision measurement of Ca isotopes (δ44/40Ca) provides a novel method to directly quantify Ca sources. To this end, we examined δ44/40Ca in rivers draining the Southern Alps of New Zealand. The Southern Alps have large tectonic and climatic gradients but nearly constant bedrock chemistry. West of the main topographic divide, uplift and precipitation rates are high, and steep, fast-flowing rivers drain schist. East of the divide, uplift and precipitation rates are low, and low-gradient, braided rivers drain either schist or greywacke. Both schist and greywacke contain up to 3% hydrothermal and metamorphic calcite. Glaciers feed several schist and greywacke catchments. Examined as δ44/40Ca versus Sr/Ca, values measured for carbonate and silicate end-members define two-component mixing envelopes. Rivers west of the divide plot within the envelope, ruling out isotopic fractionation as a factor for these streams. Several rivers east of the divide are 40Ca enriched relative to the envelope. In-situ fractionation of stream water Ca cannot explain this pattern because fractionation is expected to preferentially remove 40Ca. We measured δ42/44Ca ratios to test if chemical weathering preferentially releases 40Ca. When examined as δ40/44Ca versus δ42/44Ca, the data only display mass-dependent isotope effects. Ca in grass and the exchangeable pool of shallow soils is enriched in 40Ca relative to waters and bedrock. This Ca defines a third mixing end-member that contributes 15-30% of the Ca in rivers east of the divide. Evidence of the plant-fractionated signal likely reflects water residence times, which are longer on the eastern side of the main divide. After correcting for this input, we apportion Ca in all rivers to silicate versus carbonate weathering using a two-component mixing equation. For non-glaciated streams, the δ44/40Ca method and a conventional Ca/Na method agree within 2%. Silicate weathering contributes less Ca west of the main divide where uplift rates are highest. For actively glaciated catchments, the δ44/40Ca method attributes 26% more Ca to silicate weathering than the Ca/Na method. We ascribe this difference to non-stoichiometric leaching of Ca from freshly cleaved rock surfaces. This reaction must occur even faster than carbonate weathering, which dominates in adjacent non-glaciated watersheds. Our results support the assertion that mountain uplift does not dramatically elevate long-term atmospheric CO2 consumption rates compared to tectonically stable landscapes. However, δ44/40Ca reveals that glaciation, which is genetically linked to mountain uplift, yields moderately higher CO2 consumption rates than previously realized. Additionally, our study highlights how biological processes can influence the terrestrial Ca cycle.

76 FR 73609 - Cameron LNG, LLC; Notice of Application

Federal Register 2010, 2011, 2012, 2013, 2014

2011-11-29

... 3(a) of the Natural Gas Act (NGA) for authority to construct and operate a boil-off gas (BOG... install facilities consisting of a closed loop refrigeration system at the terminal to liquefy BOG and return such gas in the form of LNG to its storage tanks. Cameron states that the project will not require...

The hydrology of several peat deposits in northern Minnesota, U.S.A.

Treesearch

R.R. Bay

1968-01-01

A comprehensive peatland hydrology study has provided data on the climate, hydrogeology, water table levels, and run-off from forested peat deposits in northern Minnesota. Groundwater studies identified two types of hydrogeologic situations-perched bogs, independent of the underground flow system, and groundwater bogs, which were influenced by storage changes in the...

Fine-root growth in a forested bog is seasonally dynamic, but shallowly distributed in nutrient-poor peat

Treesearch

Colleen M. Iversen; Joanne Childs; Richard J. Norby; Todd A. Ontl; Randall K. Kolka; Deanne J. Brice; Karis J. McFarlane; Paul J. Hanson

2017-01-01

Background and aims. Fine roots contribute to ecosystem carbon, water, and nutrient fluxes through resource acquisition, respiration, exudation, and turnover, but are understudied in peatlands. We aimed to determine how the amount and timing of fine-root growth in a forested, ombrotrophic bog varied across gradients of vegetation density, peat...

Woodcock Bog Research Natural Area: guidebook supplement 40

Treesearch

Reid Schuller; Susan J. Fritts; Mark Mousseaux

2010-01-01

This guidebook describes Woodcock Bog Research Natural Area (RNA), a 114-ha (281-ac) area located within the Klamath-Siskiyou ecoregion in southwestern Oregon. The RNA includes a hanging fen and stream segment on ultramafic rock and derived soils. Numerous plant species occur within the fens that are endemic to the Klamath-Siskiyou Mountains of southwestern Oregon and...

Role and Responsibility of Board of Governors [BOG] in Ensuring Educational Quality in Colleges & Universities

ERIC Educational Resources Information Center

Naik, B. M.

2012-01-01

The paper presents in brief the need and importance of effective, imaginative and responsible governing boards in colleges and universities, so as to ensure educational quality. BOG should engage fruitfully with the principal and activities in college/ university. UGC, AICTE have now prescribed creation of effective boards for both government and…

Ecoenzymatic stoichiometry and microbial processing of organic matter in northern bogs and fens reveals a common P limitation among peatland types

EPA Science Inventory

We compared C, N, and P concentrations in atmospheric deposition, runoff, and soil standing stocks with microbial respiration (DHA) and ecoenzyme activity (EEA) in an ombrotrophic bog (S2) and a minerotrophic fen (S3) to investigate the environmental drivers of biogeochemical cyc...

Carbon dynamics in peatland pool systems: the role of light

NASA Astrophysics Data System (ADS)

Pickard, Amy; Heal, Kate; McLeod, Andy; Dinsmore, Kerry

2016-04-01

Open-water pools are widespread in peatlands and are considered to represent biogeochemical hotspots within the peatland landscape. However the contribution of pool systems to wider peatland C cycling has not been quantified fully and there is a lack of knowledge of the role of photochemical processes in such environments. In this study, light exposure experiments were conducted in two contrasting pools to test the reactivity of aquatic C. The first study site was located at Cross Lochs (CL), Forsinard, in the Flow Country of Northern Scotland, in a 412 m2 pool characterised by low dissolved organic carbon (DOC) concentrations (˜15 mg C L-1). The second site was located at Red Moss of Balerno (RM), a raised bog in central Scotland, in a 48 m2 pool with high DOC concentrations (˜35 mg C L-1). Experiments took place over 9 days in situ at each pool in mid-summer 2015, with 500 mL water samples contained in bags transparent to sunlight and in opaque control bags. After field exposure, optical, chemical and stable C isotope analyses were conducted on the samples. Significant differences in biogeochemical cycling of DOC were detected between the two systems, with DOC losses as a percentage of the total C pool 15% higher at RM than at CL after light exposure. The mean DOC concentration of light exposed samples at RM declined steeply initially, with 83% observed DOC degradation occurring by day 3 of the experiment. Total losses of 7.9 mg DOC L-1were observed in light exposed samples at RM, along with decreasing E4:E6 ratios, suggesting that material remaining at the end of the experiment was humified. Depletion of DOC was positively correlated with production of CO2 at both sites, with concentrations of up to 4.3 mg CO2-C L-1 recorded at RM. Stable C isotope signatures at both sites were altered under light treatment, as demonstrated by the production of enriched δ13C-DOC (+0.46 ‰ relative to opaque bags) and depleted δ13C-DIC (-0.97 ‰ relative to opaque bags) at RM. However, at CL, the δ13C-DOC signature in both the light exposed and opaque bags was depleted (-0.2‰ and -0.4 ‰ respectively), suggesting that microbial processing was the preferential DOC processing pathway in this system. These results show that C in peatland pools is highly reactive and further demonstrate the importance of photochemical processing of C, which should be considered as a significant driver of biogeochemical cycling.

Methane emission from Minnesota peatlands: Spatial and seasonal variability

NASA Astrophysics Data System (ADS)

Dise, Nancy. B.

1993-03-01

The variability of methane flux with season, year, and habitat type was investigated in northern Minnesota peatlands from September 1988 through September 1990. Average daily fluxes calculated by integration of annual data for an open poor fen, an open bog, a forested bog hollow, a fen lagg in the forested bog and a forested bog hummock were 180,118, 38, 35, and 10 mg CH4 m-2 d-1, respectively. Fluxes among the five ecosystems were significantly different from one another, although emission from all sites was highest in July and lowest in March. Winter fluxes occurred in all sites but the fen lagg. There was no difference in fluxes measured from the same sites in the spring of 1986, 1989, or 1990, but summer fluxes were significantly higher in the wetter year of 1989 than in 1990, and a summer pulse in methane emission occurred in 1989 that was not seen the next year. Concentrations of methane in pore water, reflecting the seasonal balance of production, oxidation, and release, declined during the month of peak flux, then increased to levels of about 500 μM in December. Consistent spatial and temporal differences in flux could be ascribed to differences in water table, temperature, and peat nutrient status, although additional variability remained. Integration gave an annual average flux of 20 g CH4, m-2 ot; for the three bog ecosystems and 39 g CH4, m-2 for the two fen ecosystems. This gives an estimate of 1-2 Tg CH4, yr-1 from peatlands in the Great Lake states of Minnesota, Wisconsin, and Michigan.

Delineation of peatland lagg boundaries from airborne LiDAR

NASA Astrophysics Data System (ADS)

Langlois, Melanie N.; Richardson, Murray C.; Price, Jonathan S.

2017-09-01

In Canada, peatlands are the most common type of wetland, but boundary delineation in peatland complexes has received little attention in the scientific literature. Typically, peatland boundaries are mapped as crisp, absolute features, and the transitional lagg zone—the ecotone found between a raised bog and the surrounding mineral land—is often overlooked. In this study, we aim (1) to advance existing approaches for detecting and locating laggs and lagg boundaries using airborne LiDAR surveys and (2) to describe the spatial distribution of laggs around raised bog peatlands. Two contrasting spatial analytical approaches for lagg detection were tested using five LiDAR-derived topographic and vegetation indices: topography, vegetation height, topographic wetness index, the standard deviation of the vegetation's height (as a proxy for the complexity of the vegetation's structure), and local indices of elevation variance. Using a dissimilarity approach (edge-detection, split-moving window analysis), no one variable accurately depicted both the lagg-mineral land and bog-lagg boundaries. Some indicators were better at predicting the bog-lagg boundary (i.e., vegetation height) and others at finding the lagg-mineral land boundary (i.e., topography). Dissimilarity analysis reinforces the usefulness of derived variables (e.g., wetness indices) in locating laggs, especially for those with weak topographic and vegetation gradients. When the lagg was confined between the bog and the adjacent upland, it took a linear form, parallel to the peatland's edge and was easier to predict. When the adjacent mineral land was flat or sloping away from the peatland, the lagg was discontinuous and intermittent and more difficult to predict.

Losses of Soil Carbon upon a Fire on a Drained Forested Raised Bog

NASA Astrophysics Data System (ADS)

Glukhova, T. V.; Sirin, A. A.

2018-05-01

We studied the consequences of a fire that affected 29 ha of a drained forested raised bog in Tver oblast, Central European Russia. The drainage network consisted of open 1-m-deep ditches with 60 to 160 m ditch spacing. The groundwater level (GWL) varied within the studied drained bog. We used the method of assessing the loss of soil carbon (C) based on the difference between the ash concentration in the burnt peat of the upper layer and underlying unburnt layers. The carbon loss was higher near the drainage ditches than in the sites remote from ditches. The sample median values of carbon loss (kg C/m2) were estimated at 0.37 near the drainage ditches and at 0.22 for the remote sites with a distance of 160 m between ditches. They increased to 2.23 and 0.79 near and far from the drainage ditches for 106 m ditch spacing, and ranged from 1.13 to 2.10 near the drainage ditches and were equal to 0.45 at the remote sites for 60 m ditch spacing. The maximum loss of C was at the bog margin with the 70-cm-deep GWL; the sample median was equal to 2.97 kg C/m2. The results obtained for C loss from the wildfire on the raised bog agree with the estimates obtained by other authors (1.45-4.90 kg C/m2) and confirm the importance of taking such loss into account in the estimates of the carbon budget of peat soils (Histosols).

Comparisons of soil nitrogen mass balances for an ombrotrophic bog and a minerotrophic fen in northern Minnesota

Treesearch

Brian H. Hill; Terri M. Jicha; LaRae L.P. Lehto; Colleen M. Elonen; Stephen D. Sebestyen; Randy Kolka

2016-01-01

Wecompared nitrogen (N) storage and flux in soils froman ombrotrophic bogwith that of a minerotrophic fen to quantify the differences in N cycling between these two peatlands types in northernMinnesota (USA). Precipitation, atmospheric deposition, and bog and fen outflowswere analyzed for nitrogen species. Upland and peatland soil sampleswere analyzed for N content,...

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

Rutherford, L.A.; Matthews, S.L.

A study was conducted to determine historical atmospheric mercury deposition patterns in the Maritime Provinces. Investigators measured mercury concentrations in peat cores from five ombrotrophic bogs in Kejimkujik, Fundy, Kouchibougouac, and Cape Breton Highlands national parks and in East Baltic Bog, Prince Edward Island. Results presented and discussed include deposition rates calculated using lead-210 date estimates, temporal trends in mercury concentrations, and spatial patterns of mercury deposition.

Ecoenzymatic stoichiometry and microbial processing of organic matter in northern bogs and fens reveals a common P-limitation between peatland types

Treesearch

Brian H. Hill; Colleen M. Elonen; Terri M. Jicha; Randall K. Kolka; LaRae L.P. Lehto; Stephen D. Sebestyen; Lindsey R. Seifert-Monson

2014-01-01

We compared carbon (C), nitrogen (N), and phosphorus (P) concentrations in atmospheric deposition, runoff, and soils with microbial respiration [dehydrogenase (DHA)] and ecoenzyme activity (EEA) in an ombrotrophic bog and a minerotrophic fen to investigate the environmental drivers of biogeochemical cycling in peatlands at the Marcell Experimental Forest in northern...

Effects of nutrient addition on leaf chemistry, morphology, and photosynthetic capacity of three bog shrubs

Treesearch

Jill L. Bubier; Rose Smith; Sari Juutinen; Tim R. Moore; Rakesh Minocha; Stephanie Long; Subash Minocha

2011-01-01

Plants in nutrient-poor environments typically have low foliar nitrogen (N) concentrations, long-lived tissues with leaf traits designed to use nutrients efficiently, and low rates of photosynthesis. We postulated that increasing N availability due to atmospheric deposition would increase photosynthetic capacity, foliar N, and specific leaf area (SLA) of bog shrubs. We...

[Financial Aid to Independent Students at the Post Secondary Level: The Federal Government's Role

ERIC Educational Resources Information Center

Dellenback, John

One of the new and complex issues related to student aid is the independent student controversy. The author wishes to increase the Basic Opportunity Grant (BOG) and substantially increase work study to help the independent student. For the immediate future the author would like to see: (1) The BOG refined as a major Federal grant program committed…

A keystone predator controls bacterial diversity in the pitcher-plant (Sarracenia purpurea) microecosystem.

PubMed

Peterson, Celeste N; Day, Stephanie; Wolfe, Benjamin E; Ellison, Aaron M; Kolter, Roberto; Pringle, Anne

2008-09-01

The community of organisms inhabiting the water-filled leaves of the carnivorous pitcher-plant Sarracenia purpurea includes arthropods, protozoa and bacteria, and serves as a model system for studies of food web dynamics. Despite the wealth of data collected by ecologists and zoologists on this food web, very little is known about the bacterial assemblage in this microecosystem. We used terminal restriction fragment length polymorphism (T-RFLP) analysis to quantify bacterial diversity within the pitchers as a function of pitcher size, pH of the pitcher fluid and the presence of the keystone predator in this food web, larvae of the pitcher-plant mosquito Wyeomyia smithii. Results were analysed at two spatial scales: within a single bog and across three isolated bogs. Pitchers were sterile before they opened and composition of the bacterial assemblage was more variable between different bogs than within bogs. Measures of bacterial richness and diversity were greater in the presence of W. smithii and increased with increasing pitcher size. Our results suggest that fundamental ecological concepts derived from macroscopic food webs can also be used to predict the bacterial assemblages in pitcher plants.

Nutrient limitation and morphological plasticity of the carnivorous pitcher plant Sarracenia purpurea in contrasting wetland environments.

PubMed

Bott, Terry; Meyer, Gretchen A; Young, Erica B

2008-01-01

* Plasticity of leaf nutrient content and morphology, and macronutrient limitation were examined in the northern pitcher plant, Sarracenia purpurea subsp. purpurea, in relation to soil nutrient availability in an open, neutral pH fen and a shady, acidic ombrotrophic bog, over 2 yr following reciprocal transplantation of S. purpurea between the wetlands. * In both wetlands, plants were limited by nitrogen (N) but not phosphorus (P) (N content < 2% DW(-1), N : P < 14) but photosynthetic quantum yields were high (F(V)/F(M) > 0.79). Despite carnivory, leaf N content correlated with dissolved N availability to plant roots (leaf N vs , r(2) = 0.344, P < 0.0001); carnivorous N acquisition did not apparently overcome N limitation. * Following transplantation, N content and leaf morphological traits changed in new leaves to become more similar to plants in the new environment, reflecting wetland nutrient availability. Changes in leaf morphology were faster when plants were transplanted from fen to bog than from bog to fen, possibly reflecting a more stressful environment in the bog. * Morphological plasticity observed in response to changes in nutrient supply to the roots in natural habitats complements previous observations of morphological changes with experimental nutrient addition to pitchers.

Relationship between peat geochemistry and depositional environments, Cranberry Island, Maine

USGS Publications Warehouse

Raymond, R.; Cameron, C.C.; Cohen, A.D.

1987-01-01

The Heath, Great Cranberry Island, Maine, offers a unique locality for studying lateral and vertical relationships between radically different peat types within 1 km2. The majority of The Heath is a Sphagnum moss-dominated raised bog. Surrounding the raised bog is a swamp/marsh complex containing grass, sedge, Sphagnum moss, alder, tamarack, and skunk cabbage. Swamp/ marsh-deposited peat occurs both around the margins of The Heath and under Sphagnum-dominated peat, which was deposited within the raised bog. A third peat type, dominated by herbaceous aquatics, is present underlying the swamp/marsh-dominated peat but is not present as a dominant botanical community of The Heath. The three peat types have major differences in petrographic characteristics, ash contents, and associated minerals. Sulfur contents range from a low of 0.19 wt.% (dry) within the raised bog to a high of 4.44 wt% (dry) near the west end of The Heath, where swamp/marsh peat occurring directly behind a storm beach berm has been influenced by marine waters. The presence of major geochemical variations within a 1-km2 peat deposit suggests the need for in-depth characterization of potential peat resources prior to use. ?? 1987.

Towards a universal description of cohesive-particle flows

NASA Astrophysics Data System (ADS)

Lamarche, Casey; Liu, Peiyuan; Kellogg, Kevin; Lattanzi, Aaron; Hrenya, Christine

2017-11-01

A universal framework for describing cohesive granular flows seems unattainable based on prior works, making a fundamental continuum theory to predict such flows appear unachievable. For the first time, universal behavior of cohesive-grain flows is demonstrated by linking the macroscopic (many-grain) behavior to grain-grain interactions via two dimensionless groups: a generalized Bond number BoG - ratio of maximum cohesive force to the force driving flow - and a new Agglomerate number Ag - ratio of critical cohesive energy to the granular energy. Cohesive-grain flow is investigated in several systems, and universal behavior is determined via collapse of a cohesion-dependent output variable from each system with the appropriate dimensionless group. Universal behavior is observed using BoG for dense (enduring-contact-dominated) flows and Ag for dilute (collision-dominated) flows, as BoG accounts for the cohesive contact force and Ag for increased collisional dissipation due to cohesion. Hence, a new physical picture is presented, namely, BoG dominates in dense flows, where force chains drive momentum transfer, and Ag dominates in dilute systems, where the dissipative collisions dominate momentum transfer. Apparent discrepancies with past treatments are resolved. Dow Corning Corporation.

Eutrophic mire, its characteristics and modern conditions of peat genesis

NASA Astrophysics Data System (ADS)

Inisheva, L. I.; Golubina, O. A.; Zaplatnikova, Yu. D.; Dubrovskaya, L. I.

2009-04-01

The study of structure functional organization of Siberian mire ecosystems is the base of after-effects influence of their reclamation on global changes of biosphere. The aim of this investigation is to study the structure functional organization of eutrophic mire ecosystem "Tagan". Peat deposit "Tagan" (West Siberia, 20 kilometers near Tomsk) is situated on the second flood-plain terrace of the river Tom of ancient flow channel. Maximum power of peat deposit is 9.3 meters. Subsoil is made up from sand, more seldom from loamy sand and loam. Eutrophic vegetation covers almost the whole mire. It is presented by woody sedge, sedge, sedge-moss and grass undershrub phytocenoses. The oligotrophic vegetation is presented by Sphagnum pine cotton-grass phytocenosis. There were organized three observation points on the mire in 2007. They watched dynamics of hydrothermic, redox, biological, hydrochemical regimes. There were studied physicochemical properties at given points. Peats with normal ash basically refer to grass, woody grass group of lowland type. They are characterized by high degree of decomposition which is increased down deposit. Group composition of organic matters of investigated peats showed that bitumen content in peat changes from 1.4 to 3.56%, and humid acids content is within the limits of 16.67 - 44.34 %. Water-soluble and hardly-hydrolyzed matters are contained in quantity of 19.04 - 49.76% of the whole dry peat mass. The overall nitrogen content changes within the limits of 1.76 - 3.52%. It is presented mainly by fraction of unhydrolyzed nitrogen (72.07 - 95.67% of the whole nitrogen). Highly-hydrolyzed nitrogen is the most available reserve of mineral compound of nitrogen and its content changes within the limits of 0.18 - 4.79 of the overall nitrogen. 2008 year is characterized as an average year at conditions of moistening and heat providing. Investigations, made during this year, revealed the following results. Bog waters were kept at a surface level of 20 - 69cm in summer. Peat deposit heating up to 10˚ C was observed at a depth of 120cm. Oxidizing conditions are traced up to 40 - 60cm deep. There is gradual change into restoring conditions deep in peat deposit. Very reduction conditions are observed at a depth of 60cm. Weather conditions of 2008 year were favorable for biological processes activation. In the result of their manifestation hydrochemical composition of bog waters was formed. First of all, one should pay attention to weak alkaline reaction of bog waters. Calcium content in bog waters changes from 70.2 to 150.9 mg/l. One may state calcium removal from peat deposit of eutrophic mire into an outfall. The latter is the river which is flowing along the mire. Magnesium concentration in bog waters changed within the limits of 8.5 - 42.5 mg/l. It is important to note high content of iron in individual months - up to 17.8 mg/l. Organic matters content in bog waters, which are presented by humid acids (HA) and fulvic acids (FA), is HA 3.4 - 24.65 mg/l, FA 11.0 - 58.3 mg/l. Let's, first of all, examine dynamics of individual components in bog waters. Thus, content of calcium, water-soluble carbon, and fulvic acids naturally increased in July, when it was marked combination of high temperature and minor precipitation. Active iron in bog waters had the highest concentration in spring which had gradually decreased by September (from 18 and 8 mg/l to 0.1 mg/l). Preliminary obtained results reveal bog drainage occurring at present. It is followed also from the fact that there are favorable redox conditions in a meter layer of peat deposit and high degree of peats decomposition. The examination of dynamics of hydrothermic, biological and hydrochemical regimes also is evidence of biological processes activity in eutrophic mire "Tagan". This fact, in its turn, influences on hydrochemical compound formation of bog waters.

SPRUCE Methylotrophic Methanogenesis in Sphagnum-dominated Peatland Soils – CH4 and CO2 Production in Laboratory Incubations

DOE Data Explorer

Zalman, Cassandra A.; Meade, N.; Chanton, J.; Kostka, J. E.; Bridgham, S. D.; Keller, J. K.

2017-12-01

This study investigated the potential for methylotrophic methanogenesis in three Sphagnum-dominated peatland soils in northern Minnesota. Collected soils were amended with 13C-labeled traditional substrates (acetate and sodium bicarbonate/ H2) and methylated substrates (methanol, monomethylamine (“MMA”), dimethylsulfide (“DMS”)) and monitored for δ13C-CH4, δ 13C-CO2, and net CH4 and CO2 production in laboratory incubations. The peatlands included in the study were (1) the S1 Bog, home to the SPRUCE Experiment and located at the Marcell Experimental Forest (MEF, U.S. Forest Service), (2) Bog Lake Fen, also located at the MEF, and (3) Zim Bog. These sites have been described in detail previously (Medvedeff et al., 2015)

Validating modelled data on major and trace element deposition in southern Germany using Sphagnum moss

NASA Astrophysics Data System (ADS)

Kempter, Heike; Krachler, Michael; Shotyk, William; Zaccone, Claudio

2017-10-01

Sphagnum mosses were collected from four ombrotrophic bogs in two regions of southern Germany: Upper Bavaria (Oberbayern, OB) and the Northern Black Forest (Nordschwarzwald, NBF). Surfaces of Sphagnum carpets were marked with plastic mesh and, one year later, plant matter was harvested and productivity determined. Major and trace element concentrations (Ag, Al, As, Ba, Bi, Cd, Co, Cr, Cu, Fe, Mn, Mo, Pb, Rb, Sb, Sc, Sr, Th, Ti, Tl, U, V, Zn) were determined in acid digests using sector field ICP-MS. Up to 12 samples (40 × 40 cm) were collected per site, and 6-10 sites investigated per bog. Variation in element accumulation rates within a bog is mostly the result of the annual production rate of the Sphagnum mosses which masks not only the impact of site effects, such as microtopography and the presence of dwarf trees, but also local and regional conditions, including land use in the surrounding area, topography, etc. The difference in productivity between peat bogs results in distinctly higher element accumulation rates at the NBF bogs compared to those from OB for all studied elements. The comparison with the European Monitoring and Evaluation Program (EMEP; wet-only and total deposition) and Modelling of Air Pollutants and Ecosystem Impact (MAPESI; total deposition) data shows that accumulation rates obtained using Sphagnum are in the same range of published values for direct measurements of atmospheric deposition of As, Cd, Cu, Co, Pb, and V in both regions. The accordance is very dependent on how atmospheric deposition rates were obtained, as different models to calculate the deposition rates may yield different fluxes even for the same region. In future studies of atmospheric deposition of trace metals, both Sphagnum moss and deposition collectors have to be used on the same peat bog and results compared. Antimony, however, shows considerable discrepancy, because it is either under-estimated by Sphagnum moss or over-estimated by both atmospheric deposition models. Atmospheric deposition data obtained from sampling in open fields is unlikely to always perfectly match data obtained using living Sphagnum moss from bogs. In fact, plant uptake and biochemical utilization by living moss may affect accumulation rates of those elements that are essential for plant nutrition (macro and micronutrients), which is clearly seen in the data presented here for Mn, Fe and Zn. Furthermore, Sphagnum moss is a unique receptor, with its characteristic roughness and chemical complexity. These two aspects, combined with conditions found on the bog surface (variations in microtopography, shrubs, trees, wetness, snow cover, etc.), result in a unique type of interception and retention. Despite all these factors, the comparison with modelled data shows that Sphagnum moss is a good indicator of atmospheric deposition at least in a semi-quantitative manner and certainly reflects inputs to terrestrial ecosystems.

The Paradox of Excess Nitrogen in Boreal Peatlands: Biogeochemical Gaps in Nitrogen Cycling Revealed

NASA Astrophysics Data System (ADS)

Vile, M. A.; Prsa, T.; Wieder, R.; Lamers, L. P.

2011-12-01

Globally, peatlands cover 3-4 % of the Earth's land surface (over 4 million km 2, yet they store 25-30 % of the world's soil carbon (C) and 9-16% of the world's soil nitrogen (N, 8-15 Pg) in peat. As in other terrestrial ecosystems, the cycling of C and N is closely linked, especially for ombrotrophic bogs. Bogs receive nutrient and water exclusively from the atmosphere, which ensures an N-limited, nutrient-poor habitat. In Alberta, NW Canada, peatlands have received exceptionally low atmospheric inputs of N (< 1 7 kg/ha/yr) from their first introduction on the landscape ~ 7000 yrs bp, up to the present time. Paradoxically, despite these low inputs of atmospheric N deposition, bases on 210-fixation Pb dating of peat cores, we have shown that over the past 50 years these bogs have accumulated approximately 11-21 times more N in peat than can be explained by inputs of atmospheric N. A likely missing input is N2-fixation from cyanobacteria associated with Sphagnum mosses, however this process has been largely overlooked in boreal peatlands. Here we demonstrate the importance of N2-fixation in explaining the high accumulation rates of N found in unpolluted, boreal bogs of western Canada. Calibrated (using theoretical ratio of 1.5-3:1) rates of N2-fixation for 4 bogs in northern Alberta ranged from 1.6 to 8.0 ± 0.7 kg/ha/yr, indicating that 42-58 % of the N accumulated over in peat, can be attributed to biological N2-fixation. Although most of northern Alberta's peatlands continue to receive exceptionally low atmospheric N deposition rates, over the last 3 decades, rapid development and industrial expansion of Alberta's Oil Sands Mining (OSM) potentially threaten the pristine nature of peatlands through regionally elevated deposition of N-compounds (NOx). Prior to OSM, N inputs to bogs were limited exclusively to (1) biological N fixation, and (2) bulk background deposition. We examined the response of peatlands located in the OSM area to enhanced N deposition. Despite the large accumulation rates of N in peat, mean N:P ratios in Sphagnum moss capitula (11.0 ± 3.4; mean ± stdev) suggest that peat of boreal western Canada is still severely N limited and not limited by phosphorus. Collectively, these data underscore the severity of N-limitation in pristine bogs and their potential sensitivity to increased N inputs from oils sands mining. Additionally, because the majority of the data generated for N stress in peatlands is from eastern Canada and western Europe, we stress the need to encompass the response of bogs to N deposition within the bounds of the low N deposition gradient. We postulate the loss of symbiosis between Sphagnum and N-fixing microorganisms (cyanobacteria, bacteria) in nitrogen-polluted areas, and indicate its consequences at the species level (trade-off) and ecosystem level (including C sequestration).

Seasonal variations in CO2 and CH4 fluxes of four different plant compositions of a Sphagnum-dominated Alpine peat bog

NASA Astrophysics Data System (ADS)

Drollinger, Simon; Maier, Andreas; Karer, Jasmin; Glatzel, Stephan

2017-04-01

Peatlands are the only type of ecosystems which have the ability to accumulate significant amounts of carbon (C) under undisturbed conditions. The amount of C sequestered in peatlands depends on the balance between gross primary production, ecosystem respiration and decomposition of plant material. Sphagnum-dominated bogs possess the greatest peat accumulation potential of all peatlands, thus in turn, feature highest C release potentials. Many studies report about the C balances of undisturbed northern peat bogs, however, little is known about the effects of peatland degradation on the C balance between different plant compositions within peat bog ecosystems. Particularly in the Alpine region, where temperature increase during the last century has been almost twice as high as the global mean. The investigated peat bog is located in the inner Alpine Enns valley in the Eastern Alps, Austria (N 47˚ 34.873' E 14˚ 20.810'). It is a pine peat bog covered by Sphagnum mosses and a present extent of about 62 ha. Due to increasing differences in surface height of the peatland compared to the surrounding areas and related lowered water retention capacity attributed to the subsidence of the adjacent intensively managed meadows on deeply drained peat soils, the function of the peatland as a carbon sink is strongly endangered. Hence, the current mean water table depth of the central peat bog area is about -12 cm. To reveal differences in peatland-atmosphere C exchanges within the peatland ecosystem, we investigated CO2 and CH4 fluxes of four different vegetation compositions (PM1-PM4) at the treeless central peat bog area. PM1 is dominated by the graminoids Rhynchospora alba and Eriophorum vaginatum. PM2 is inhabited by small individuals (< 35 cm) of the conifer Pinus mugo, whereas PM3 is dominated by the ericaceous plant Calluna vulgaris. PM4 again is populated by Pinus mugo, but higher growing (35 - 60 cm) and with corresponding higher amount of biomass. Fluxes were measured for at least 120 seconds with the closed dynamic chamber method using infrared gas analysers (UGGA, Los Gatos Research and LI-802, LI-COR Biosciences) at four study sites with three replicates each. Net ecosystem exchange was measured using transparent chambers, whereas soil respiration was revealed using opaque chambers. Measurements were conducted seasonally during the last two years with eight sampling periods. Here, we demonstrate the seasonal variations in CO2 and CH4 fluxes, evaluate the underlying factors being responsible for these variations, examine the differences in diurnal pattern during the seasons and compute the global warming potentials of the released greenhouse gases. Moreover, we estimate the annual C balance per site and revise the seasonal C fluxes by comparing the results with fluxes derived by eddy covariance method.

The impact of 90 years of drainage works on some chemical properties of raised peat bog organic soils - case study from valley of the Upper San river in Polish Bieszczady Mts. (Eastern Carpathians).

NASA Astrophysics Data System (ADS)

Stolarczyk, Mateusz

2016-04-01

Wetland ecosystems, including raised peat bogs are characterized by a specific water conditions and unique vegetation, which makes peatland highly important habitats due to protection of biodiversity. Transformation of peat bog areas is particularly related to changes in the environment e.g. according to reclamation works. Drainage of peatlands is directly associated to the decrease of groundwater levels and lead to a number of changes in the chemical and physical properties of peat material, included contents of exchangeable cations in the surface layers of peat soils in the decession phase of peat development and release above compounds from the soil to ground or surface waters. The aim of the research was to determine the impact of extended drainage works on chemical composition of sorption complex of raised peat bog organic soils and identification the potential environmental effects of alkaline cations leaching to the surface waters. Research was carried out on the peat bogs located in the Upper San valley in Polish Bieszczady Mts. (Eastern Carpathians). Soil samples used in this study were collected from 3 soil profiles in 10 or 20 cm intervals to the approximately 130 cm depth. Laboratory analyses included determination of basic properties of organic material such as the degree of peat decomposition, ash content, soil pH and carbon, hydrogen, nitrogen concentrations. Additionally the amount of alkaline cations, exchangeable and extractable acidity was determined. Furthermore, the degree of saturation of the sorption complex with alkaline cations (V) and cation exchange capacity (CEC) are calculated. In order to evaluate the impact of the examined peat bog to the environment, also water samples were collected and ions composition was measured. The obtained results show that studied organic soils are oligotrophic and strongly acidic. In the case of organic material related to decession phase of peat development, as a result of the lengthy drainage works, increased pH values, changes in the morphology of the peat, high nitrogen contents and lower values of C/N ratios are noticed. The increased contents of calcium, occurred in soil layers comprised of moorsh forming process are probably the effect of peat mineralization process or changes in the chemistry and fluctuations of groundwater levels. As a result of above factors, increased calcium and magnesium concentrations in surface waters in the immediate vicinity of investigated bogs are observed.

Southern Hemisphere bog persists as a strong carbon sink during droughts

NASA Astrophysics Data System (ADS)

Goodrich, Jordan P.; Campbell, David I.; Schipper, Louis A.

2017-10-01

Peatland ecosystems have been important global carbon sinks throughout the Holocene. Most of the research on peatland carbon budgets and effects of variable weather conditions has been done in Northern Hemisphere Sphagnum-dominated systems. Given their importance in other geographic and climatic regions, a better understanding of peatland carbon dynamics is needed across the spectrum of global peatland types. In New Zealand, much of the historic peatland area has been drained for agriculture but little is known about rates of carbon exchange and storage in unaltered peatland remnants that are dominated by the jointed wire rush, Empodisma robustum. We used eddy covariance to measure ecosystem-scale CO2 and CH4 fluxes and a water balance approach to estimate the sub-surface flux of dissolved organic carbon from the largest remaining raised peat bog in New Zealand, Kopuatai bog. The net ecosystem carbon balance (NECB) was estimated over four years, which included two drought summers, a relatively wet summer, and a meteorologically average summer. In all measurement years, the bog was a substantial sink for carbon, ranging from 134.7 to 216.9 gC m-2 yr-1, owing to the large annual net ecosystem production (161.8 to 244.9 gCO2-C m-2 yr-1). Annual methane fluxes were large relative to most Northern Hemisphere peatlands (14.2 to 21.9 gCH4-C m-2 yr-1), although summer and autumn emissions were highly sensitive to dry conditions, leading to very predictable seasonality according to water table position. The annual flux of dissolved organic carbon was similar in magnitude to methane emissions but less variable, ranging from 11.7 to 12.8 gC m-2 yr-1. Dry conditions experienced during late summer droughts led to significant reductions in annual carbon storage, which resulted nearly equally from enhanced ecosystem respiration due to lowered water tables and increased temperatures, and from reduced gross primary production due to vapor pressure deficit-related stresses to the vegetation. However, the net C uptake of Kopuatai bog during drought years was large relative to even the maximum reported NECB from Northern Hemisphere bogs. Furthermore, global warming potential fluxes indicated the bog was a strong sink for greenhouse gases in all years despite the relatively large annual methane emissions. Our results suggest that adaptations of E. robustum to dry conditions lead to a resilient peatland drought response of the NECB.

Atmospheric Inputs of Mercury and Organic Carbon into a Forested Upland/Bog Watershed

Treesearch

Randall K. Kolka; E.A. Nater; D.F. Grigal; E.S. Verry

1999-01-01

Inputs of mercury (Hg) and dissolved organic carbon (DOC) in throughfall and stemflow waters were measured for an upland/bog watershed in northern Minnesota, and were compared to the deposition in a nearby opening to determine the influence of tree canopies on Hg and DOC deposition. Twice as much Hg and seven times as much DOC was deposited in the forested watershed...

Dynamic vertical profiles of peat porewater chemistry in a northern peatland

Treesearch

Natalie A. Griffiths; Stephen D. Sebestyen

2016-01-01

We measured pH, cations, nutrients, and total organic carbon (TOC) over 3 years to examine weekly to monthly variability in porewater chemistry depth profiles (0–3.0 m) in an ombrotrophic bog in Minnesota, USA. We also compared temporal variation at one location to spatial variation in depth profiles at 16 locations across the bog. Most solutes exhibited large...

Towards a conceptual model of hydrological change on an abandoned cutover bog, Quebec

NASA Astrophysics Data System (ADS)

van Seters, Tim E.; Price, Jonathan S.

2002-07-01

Cutover bogs do not return to functional peatland ecosystems after abandonment because re-establishment of peat-forming mosses is poor. This paper presents a conceptual model of bog disturbance caused by peat harvesting (1942-1972), and the hydrological evolution that occurred after abandonment (1973-1998). Two adjacent bogs of similar size and origin, one harvested and the other essentially undisturbed, provide the basis for understanding what changes occurred. The model is based on historical trends evident from previous surveys of land-use, bog ecology and resource mapping; and from recent hydrological and ecological data that characterize the current condition. Water balance data and historical information suggest that runoff increased and evapotranspiration decreased following drainage, but tended towards pre-disturbance levels following abandonment, as vegetation recolonized the surface and drainage became less efficient over time. Dewatering of soil pores after drainage caused shrinkage and oxidation of the peat and surface subsidence of approximately 80 cm over 57 years. Comparisons with a nearby natural bog suggest that bulk density in the upper 50 cm of cutover peat increased from 0·07 to 0·13 g cm-3, specific yield declined from 0·14 to 0·07, water table fluctuations were 67% greater, and mean saturated hydraulic conductivity declined from 4·1 × 10-5 to 1·3 × 10-5 cm s-1. More than 25 years after abandonment, Sphagnum mosses were distributed over broad areas but covered less than 15% of the surface. Areas with good Sphagnum regeneration (>10% cover) were strongly correlated with high water tables (mean -22 cm), especially in zones of seasonal groundwater discharge, artefacts of the extraction history. Forest cover expanded from 5 to 20% of the study area following abandonment. The effect of forest growth (transpiration and interception) and drainage on lowering water levels eventually will be countered by slower water movement through the increasingly dense soil, and by natural ditch deterioration. However, without management intervention, full re-establishment of natural hydrological functions will take a very long time.

Water Table Depth Reconstruction in Ombrotrophic Peatlands Using Biomarker Abundance Ratios and Compound-Specific Hydrogen Isotope Composition

NASA Astrophysics Data System (ADS)

Nichols, J. E.; Jackson, S. T.; Booth, R. K.; Pendall, E. G.; Huang, Y.

2005-12-01

Sediment cores from ombrotrophic peat bogs provide sensitive records of changes in precipitation/evaporation (P/E) balance. Various proxies have been developed to reconstruct surface moisture conditions in peat bogs, including testate amoebae, plant macrofossils, and peat humification. Studying species composition of testate amoeba assemblages is time consuming and requires specialized training. Humification index can be influenced by environmental factors other than moisture balance. The plant macrofossil proxy is less quantitative and cannot be performed on highly decomposed samples. We demonstrate that the ratio of C23 alkane to C29 alkane abundance may provide a simple alternative or complementary means of tracking peatland water-table depth. Data for this proxy can be collected quickly using a small sample (100 mg dry). Water-table depth decreases during drought, and abundance of Sphagnum, the dominant peat-forming genus, decreases as vascular plants increase. Sphagnum moss produces mainly medium chain-length alkanes (C21-C25) while vascular plants (grasses and shrubs) produce primarily longer chain-length alkanes (C27-C31). Therefore, C23:C29 n-alkane ratios quantitatively track the water table depth fluctuations in peat bogs. We compared C23:C29 n-alkane ratios in a core from Minden Bog (southeastern Michigan) with water table depth reconstructions based on testate-amoeba assemblages and humification. The 184-cm core spans the past ~3kyr of continuous peat deposition in the bog. Our results indicate that the alkane ratios closely track the water table depth variations, with C29 most abundant during droughts. We also explored the use of D/H ratios in Sphagnum biomarkers as a water-table depth proxy. Compound-specific hydrogen isotope ratio analyses were performed on Sphagnum biomarkers: C23 and C25 alkane and C24 acid. Dry periods are represented in these records by an enrichment of deuterium in these Sphagnum-specific compounds. These events also correlate with drought events in the testate amoeba record and the alkane abundance ratio record. These biogeochemical proxies can be used in paleohydrological studies of ombrotrophic bogs and provide a new and complimentary source of data from these underutilized paleoclimate archives.

Holocene palaeohydrological history of the Tǎul Muced peat bog (Northern Carpathians, Romania) based on testate amoebae (Protozoa) and plant macrofossils

NASA Astrophysics Data System (ADS)

Cosmin Diaconu, Andrei; Feurdean, Angelica; Lamentowicz, Mariusz; Gałka, Mariusz; Tanţǎu, Ioan

2016-04-01

Knowledge of past local vs. regional hydro-climate variability is a priority in climate research. This is because ecosystems and human depend on local climatic conditions and the magnitude of these climate changes is more variable at local and regional rather than at global scales. Ombrotrophic bogs are highly suitable for hydro-climate reconstructions as they are entirely dependent on the water from precipitation. We used stratigraphy, radiocarbon dating, testate amoebae (TA) and plant macrofossils on a peat profile from an ombrotrophic bog (Tǎul Muced) located in the Biosphere Reserve of the Rodna National Park Romania. We performed quantitative reconstruction of the depth to water table (DWT) and pH over the last 8000 years in a continental area of CE Europe. We identified six main stages in the development of the bog based on changes in TA assemblages in time. Wet conditions and pH between 2 and 4.5 were recorded between 4600-2750 and 1300-400 cal. yr BP, by the occurrence of Archerella flavum, Amphitrema wrightianum and Hyalosphenia papilio. This was associated to a local vegetation primarily composed of Sphagnum magellanicum and S. angustifolium. Dry stages and pH of 2.5 to 5 were inferred between 7550-4600, 2750-1300 and -50 cal. yr BP, by the dominance of Nebela militaris, Difflugia pulex and Phryganella acropodia. These overall dry conditions were also connected with increased abundance of Eriophorum vaginatum. The period between 400 and -50 cal. yr BP was characterized by a rapid shift from dry to wet conditions on the surface of the bog. Vegetation shifted from Sphagnum magellanicum to Sphagnum russowii dominated community. Our reconstruction remains in relatively good agreement with other palaeohydrological records from Central Eastern Europe. However, it shows contrasting conditions to others particularly with records from NW Europe. The valuable information regarding bog hydrology offered by our record puts an accent on the need of more regional TA based reconstruction studies, to get a compressive picture of larger spatial scales of hydro-climate variability in Europe.

Detecting Changes in a Permafrost Peatland from 1943 to 2013 with Historical and Recent Remote Sensing Data.

NASA Astrophysics Data System (ADS)

Persson, A.; Connolly, J.

2016-12-01

Peatlands or mires contain about one third of the global terrestrial carbon pool and are located on between 3-6% of the global land area. In boreal and sub-arctic permafrost peatlands the soil organic carbon (SOC) pools are stable and decomposition is suspended only as long as the soil is frozen. Climate warming is projected to be greater in the high latitudes, observed mean annual air temperatures in northern Sweden have increased by 2-3oC since the 1950s. Thawing permafrost leads to new hydrological regimes potentially leading to increased production of methane. In this study, two sets of data were analysed: (i) a stereo-pair of black and white aerial photographs acquired in August 1943 by the Swedish Airforce, with a spatial resolution of 50cm, and (ii) a geo-rectified Worldview2 (WV2) multispectral image acquired on the 24th of July, 2013. The aerial photographs were digitized using a very high resolution camera, georeferenced and incorporated into a geodatabase. The analysis of image areas was performed by heads-up visual interpretation both on a computer monitor and through stereoscopes. The aim was to identify wet and dry areas in the palsa peatland. Feature Analyst (FA) object oriented image analysis (OBIA) was used with the WV2 dataset to extract features that are related to the hydrological state of the mire. Feature Analyst is an extension to ArcGIS. The method uses a black box algorithm that can be adjusted with several parameters to aid classification and feature extraction in an image. Previous studies that analysed aerial photographs from 1970 and 2000 showed that there was an increase in the amount of wet areas on the Swedish palsa bog mire Stordalen. In this study we determine the change in wet areas over a seventy-year period. The central part of the palsa mire has been extensively studied as it has been presumed that it has collapsed due to warmer temperatures in recent decades. However, our analysis shows that much of the internal hydrological patterns on this part of the palsa bog seem to be temporally stable, at least since 1943. Macro changes not identified in previous studies are observed here where it can be seen that the extent of the palsa has retreated, in areas contiguous to streamflow, possibly in response to contact with relatively warmer streamflow.

The Relative Importance of Methanogenesis in the Decomposition of Organic Matter in Northern Peatlands

NASA Technical Reports Server (NTRS)

Corbett, J. Elizabeth; Tfaily, Malak M.; Burdige, David J.; Glaser, Paul H.; Chanton, Jeffrey P.

2015-01-01

Using an isotope-mass balance approach and assuming the equimolar production of CO2 and CH4 from methanogenesis (e.g., anaerobic decomposition of cellulose), we calculate that the proportion of total CO2 production from methanogenesis varies from 37 to 83% across a variety of northern peatlands. In a relative sense, methanogenesis was a more important pathway for decomposition in bogs (80 +/- 13% of CO2 production) than in fens (64 +/- 5.7% of CO2 production), but because fens contain more labile substrates they may support higher CH4 production overall. The concentration of CO2 produced from methanogenesis (CO2-meth) can be considered equivalent to CH4 concentration before loss due to ebullition, plant-mediated transport, or diffusion. Bogs produced slightly less CO2-meth than fens (2.9 +/- 1.3 and 3.7 +/- 1.4 mmol/L, respectively). Comparing the quantity of CH4 present to CO2-meth, fens lost slightly more CH4 than bogs (89 +/- 2.8% and 82 +/- 5.3%, respectively) likely due to the presence of vascular plant roots. In collapsed permafrost wetlands, bog moats produced half the amount of CO2-meth (0.8 +/- 0.2mmol/L) relative to midbogs (1.6 +/- 0.6 mmol/L) and methanogenesis was less important (42 +/- 6.6% of total CO2 production relative to 55 +/- 8.1%).We hypothesize that the lower methane production potential in collapsed permafrost wetlands occurs because recently thawed organic substrates are being first exposed to the initial phases of anaerobic decomposition following collapse and flooding. Bog moats lost a comparable amount of CH4 as midbogs (63 +/- 7.0% and 64 +/- 9.3%).

Identification of runoff formation with two dyes in a mid-latitude mountain headwater

NASA Astrophysics Data System (ADS)

Vlček, Lukáš; Falátková, Kristýna; Schneider, Philipp

2017-06-01

Subsurface flow in peat bog areas and its role in the hydrologic cycle has garnered increased attention as water scarcity and floods have increased due to a changing climate. In order to further probe the mechanisms in peat bog areas and contextualize them at the catchment scale, this experimental study identifies runoff formation at two opposite hillslopes in a peaty mountain headwater; a slope with organic peat soils and a shallow phreatic zone (0.5 m below surface), and a slope with mineral Podzol soils and no detectable groundwater (> 2 m below surface). Similarities and differences in infiltration, percolation and preferential flow paths between both hillslopes could be identified by sprinkling experiments with Brilliant Blue and Fluorescein sodium. To our knowledge, this is the first time these two dyes have been compared in their ability to stain preferential flow paths in soils. Dye-stained soil profiles within and downstream of the sprinkling areas were excavated parallel (lateral profiles) and perpendicular (frontal profiles) to the slopes' gradients. That way preferential flow patterns in the soil could be clearly identified. The results show that biomat flow, shallow subsurface flow in the organic topsoil layer, occurred at both hillslopes; however, at the peat bog hillslope it was significantly more prominent. The dye solutions infiltrated into the soil and continued either as lateral subsurface pipe flow in the case of the peat bog, or percolated vertically towards the bedrock in the case of the Podzol. This study provides evidence that subsurface pipe flow, lateral preferential flow along decomposed tree roots or logs in the unsaturated zone, is a major runoff formation process at the peat bog hillslope and in the adjacent riparian zone.

Atmospheric Pb and Ti accumulation rates from Sphagnum moss: dependence upon plant productivity.

PubMed

Kempter, H; Krachler, M; Shotyk, W

2010-07-15

The accumulation rates of atmospheric Pb and Ti were obtained using the production rates of Sphagnum mosses collected in four ombrotrophic bogs from two regions of southern Germany: Upper Bavaria (Oberbayern, OB) and the Northern Black Forest (Nordschwarzwald, NBF). Surfaces of Sphagnum carpets were marked with plastic mesh and one year later the production of plant matter was harvested. Metal concentrations were determined in acid digests using sector field ICP-MS employing well established analytical procedures. Up to 12 samples (40 x 40 cm) were collected per site, and 6-10 sites were investigated per bog. Variations within a given sampling site were in the range 2.3-4x for Pb concentrations, 1.8-2.5x for Ti concentrations, 3-8.3x for Pb/Ti, 5.6-7.8x for Pb accumulation rates, and 2.3-6.4x for Ti accumulation rates. However, the median values of these parameters for the sites (6-10 per bog) were quite consistent. The mosses from the bogs in NBF exhibited significantly greater productivity (187-202 g m(-2) a(-1)) compared to the OB peat bogs (71-91 g m(-2) a(-1)), and these differences had a pronounced effect on the Pb and Ti accumulation rates. Highly productive mosses showed no indication of a "dilution effect" of Pb or Ti concentrations, suggesting that more productive plants were simply able to accumulate more particles from the air. The median rates of net Pb accumulation by the mosses are in excellent agreement with the fluxes obtained by direct atmospheric measurements at nearby monitoring stations in both regions (EMEP and MAPESI data).

Differential response of carbon fluxes to climate in three peatland ecosystems that vary in the presence and stability of permafrost

USGS Publications Warehouse

Euskirchen, Eugenie S; Edgar, C.W.; Turetsky, M.R.; Waldrop, Mark P.; Harden, Jennifer W.

2016-01-01

Changes in vegetation and soil properties following permafrost degradation and thermokarst development in peatlands may cause changes in net carbon storage. To better understand these dynamics, we established three sites in Alaska that vary in permafrost regime, including a black spruce peat plateau forest with stable permafrost, an internal collapse scar bog formed as a result of thermokarst, and a rich fen without permafrost. Measurements include year-round eddy covariance estimates of carbon dioxide (CO2), water, and energy fluxes, associated environmental variables, and methane (CH4) fluxes at the collapse scar bog. The ecosystems all acted as net sinks of CO2 in 2011 and 2012, when air temperature and precipitation remained near long-term means. In 2013, under a late snowmelt and late leaf out followed by a hot, dry summer, the permafrost forest and collapse scar bog were sources of CO2. In this same year, CO2 uptake in the fen increased, largely because summer inundation from groundwater inputs suppressed ecosystem respiration. CO2 exchange in the permafrost forest and collapse scar bog was sensitive to warm air temperatures, with 0.5 g C m−2 lost each day when maximum air temperature was very warm (≥29°C). The bog lost 4981 ± 300 mg CH4 m−2 between April and September 2013, indicating that this ecosystem acted as a significant source of both CO2 and CH4 to the atmosphere in 2013. These results suggest that boreal peatland responses to warming and drying, both of which are expected to occur in a changing climate, will depend on permafrost regime.

The relative importance of methanogenesis in the decomposition of organic matter in northern peatlands

NASA Astrophysics Data System (ADS)

Corbett, J. Elizabeth; Tfaily, Malak M.; Burdige, David J.; Glaser, Paul H.; Chanton, Jeffrey P.

2015-02-01

Using an isotope-mass balance approach and assuming the equimolar production of CO2 and CH4 from methanogenesis (e.g., anaerobic decomposition of cellulose), we calculate that the proportion of total CO2 production from methanogenesis varies from 37 to 83% across a variety of northern peatlands. In a relative sense, methanogenesis was a more important pathway for decomposition in bogs (80 ± 13% of CO2 production) than in fens (64 ± 5.7% of CO2 production), but because fens contain more labile substrates they may support higher CH4 production overall. The concentration of CO2 produced from methanogenesis (CO2-meth) can be considered equivalent to CH4 concentration before loss due to ebullition, plant-mediated transport, or diffusion. Bogs produced slightly less CO2-meth than fens (2.9 ± 1.3 and 3.7 ± 1.4 mmol/L, respectively). Comparing the quantity of CH4 present to CO2-meth, fens lost slightly more CH4 than bogs (89 ± 2.8% and 82 ± 5.3%, respectively) likely due to the presence of vascular plant roots. In collapsed permafrost wetlands, bog moats produced half the amount of CO2-meth (0.8 ± 0.2 mmol/L) relative to midbogs (1.6 ± 0.6 mmol/L) and methanogenesis was less important (42 ± 6.6% of total CO2 production relative to 55 ± 8.1%). We hypothesize that the lower methane production potential in collapsed permafrost wetlands occurs because recently thawed organic substrates are being first exposed to the initial phases of anaerobic decomposition following collapse and flooding. Bog moats lost a comparable amount of CH4 as midbogs (63 ± 7.0% and 64 ± 9.3%).

Late Holocene and modern pollen records from three sites in Shannon and Carter Counties, southeast Missouri Ozarks

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

Huber, J.K.

Palynological investigations of a small sinkhole bog (Buttonbush Bog) and two archaeological sites (Round Spring Shelter, Round Spring Site 23SH19 and Gooseneck Site 23CT54) located in Shannon and Carter counties, Missouri provide a 3,100 year record of vegetational change. Bryophytic polsters and surface samples were also collected in Shannon and Carter counties in the southeast Missouri Ozarks to determine modern pollen rain. A 302-cm core retrieved from Buttonbush Bog has a basal data of 3,130 [+-] 100 yr B.P. and a date of 1,400 [+-] 100 yr B.P. at 52--56 cm. The Buttonbush Bog pollen sequence is divided into threemore » pollen-assemblage zones. The pollen spectra from Buttonbush Bog indicate that pine did not become well established in the southeast Missouri Ozarks until after 3,100 yr B.P. Zone 1 (the oldest) represents a mixed oak forest with minor components of pine and hickory. In Zone 2, pine values increase, indicating a shift to a pine-oak forest. The pollen sequence from Round Spring Shelter is divided into two pollen-assemblage zones. The lower zone (Zone 1) suggests the presence of a pine-oak forest in the vicinity of Round Spring prior to an Ambrosia rise at the top of the sequence in Zone 2. Regional pollen rain and variation in the local pollen rain are reflected by modern pollen spectra extracted from the bryophytic polsters surface samples. In this area the average regional pollen rain is dominated by pine, oak, hickory, and Ambrosia. The data are consistent with the mosaic of pine-oak and oak-hickory-pine forests characteristic of this region.« less

Methane flux from Minnesota Peatlands

NASA Astrophysics Data System (ADS)

Crill, P. M.; Bartlett, K. B.; Harriss, R. C.; Gorham, E.; Verry, E. S.; Sebacher, D. I.; Madzar, L.; Sanner, W.

1988-12-01

Northern (>40°N) wetlands have been suggested as the largest natural source of methane (CH4) to the troposphere. To refine our estimates of source strengths from this region and to investigate climatic controls on the process, fluxes were measured from a variety of Minnesota peatlands during May, June, and August 1986. Sites included forested and unforested ombrotrophic bogs and minerotrophic fens in and near the U.S. Department of Agriculture Marcell Experimental Forest and the Red Lake peatlands. Late spring and summer fluxes ranged from 11 to 866 mg CH4 m-2 d-1, averaging 207 mg CH4 m-2 d-1 overall. At Marcell Forest, forested bogs and fen sites had lower fluxes (averages of 77 ± 21 mg CH4 m-2 d-1 and 142 ± 19 mg CH4 m-2 d-1) than open bogs (average of 294 ± 30 mg CH4 m-2 d-1). In the Red Lake peatland, circumneutral fens, with standing water above the peat surface, produced more methane than acid bog sites in which the water table was beneath the moss surface (325 ± 31 and 102 ± 13 mg CH4 m-2 d-1, respectively). Peat temperature was an important control. Methane flux increased in response to increasing soil temperature. For example, the open bog in the Marcell Forest with the highest CH4 flux exhibited a 74-fold increase in flux over a three-fold increase in temperature. We estimate that the methane flux from all peatlands north of 40° may be on the order of 70 to 90 Tg/yr though estimates of this sort are plagued by uncertainties in the areal extent of peatlands, length of the CH4 producing season, and the spatial and temporal variability of the flux.

A synthesis of methane emissions from 71 northern, temperate, and subtropical wetlands.

PubMed

Turetsky, Merritt R; Kotowska, Agnieszka; Bubier, Jill; Dise, Nancy B; Crill, Patrick; Hornibrook, Ed R C; Minkkinen, Kari; Moore, Tim R; Myers-Smith, Isla H; Nykänen, Hannu; Olefeldt, David; Rinne, Janne; Saarnio, Sanna; Shurpali, Narasinha; Tuittila, Eeva-Stiina; Waddington, J Michael; White, Jeffrey R; Wickland, Kimberly P; Wilmking, Martin

2014-07-01

Wetlands are the largest natural source of atmospheric methane. Here, we assess controls on methane flux using a database of approximately 19 000 instantaneous measurements from 71 wetland sites located across subtropical, temperate, and northern high latitude regions. Our analyses confirm general controls on wetland methane emissions from soil temperature, water table, and vegetation, but also show that these relationships are modified depending on wetland type (bog, fen, or swamp), region (subarctic to temperate), and disturbance. Fen methane flux was more sensitive to vegetation and less sensitive to temperature than bog or swamp fluxes. The optimal water table for methane flux was consistently below the peat surface in bogs, close to the peat surface in poor fens, and above the peat surface in rich fens. However, the largest flux in bogs occurred when dry 30-day averaged antecedent conditions were followed by wet conditions, while in fens and swamps, the largest flux occurred when both 30-day averaged antecedent and current conditions were wet. Drained wetlands exhibited distinct characteristics, e.g. the absence of large flux following wet and warm conditions, suggesting that the same functional relationships between methane flux and environmental conditions cannot be used across pristine and disturbed wetlands. Together, our results suggest that water table and temperature are dominant controls on methane flux in pristine bogs and swamps, while other processes, such as vascular transport in pristine fens, have the potential to partially override the effect of these controls in other wetland types. Because wetland types vary in methane emissions and have distinct controls, these ecosystems need to be considered separately to yield reliable estimates of global wetland methane release. © 2014 John Wiley & Sons Ltd.

A synthesis of methane emissions from 71 northern, temperate, and subtropical wetlands

USGS Publications Warehouse

Turetsky, Merritt R.; Kotowska, Agnieszka; Bubier, Jill; Dise, Nancy B.; Crill, Patrick; Hornibrook, Ed R.C.; Minkkinen, Kari; Moore, Tim R.; Myers-Smith, Isla H.; Nykanen, Hannu; Olefeldt, David; Rinne, Janne; Saarnio, Sanna; Shurpali, Narasinha; Tuittila, Eeva-Stiina; Waddington, J. Michael; White, Jeffrey R.; Wickland, Kimberly P.; Wilmking, Martin

2014-01-01

Wetlands are the largest natural source of atmospheric methane. Here, we assess controls on methane flux using a database of approximately 19 000 instantaneous measurements from 71 wetland sites located across subtropical, temperate, and northern high latitude regions. Our analyses confirm general controls on wetland methane emissions from soil temperature, water table, and vegetation, but also show that these relationships are modified depending on wetland type (bog, fen, or swamp), region (subarctic to temperate), and disturbance. Fen methane flux was more sensitive to vegetation and less sensitive to temperature than bog or swamp fluxes. The optimal water table for methane flux was consistently below the peat surface in bogs, close to the peat surface in poor fens, and above the peat surface in rich fens. However, the largest flux in bogs occurred when dry 30-day averaged antecedent conditions were followed by wet conditions, while in fens and swamps, the largest flux occurred when both 30-day averaged antecedent and current conditions were wet. Drained wetlands exhibited distinct characteristics, e.g. the absence of large flux following wet and warm conditions, suggesting that the same functional relationships between methane flux and environmental conditions cannot be used across pristine and disturbed wetlands. Together, our results suggest that water table and temperature are dominant controls on methane flux in pristine bogs and swamps, while other processes, such as vascular transport in pristine fens, have the potential to partially override the effect of these controls in other wetland types. Because wetland types vary in methane emissions and have distinct controls, these ecosystems need to be considered separately to yield reliable estimates of global wetland methane release.

Species Identification of Archaeological Skin Objects from Danish Bogs: Comparison between Mass Spectrometry-Based Peptide Sequencing and Microscopy-Based Methods

PubMed Central

Brandt, Luise Ørsted; Schmidt, Anne Lisbeth; Mannering, Ulla; Sarret, Mathilde; Kelstrup, Christian D.; Olsen, Jesper V.; Cappellini, Enrico

2014-01-01

Denmark has an extraordinarily large and well-preserved collection of archaeological skin garments found in peat bogs, dated to approximately 920 BC – AD 775. These objects provide not only the possibility to study prehistoric skin costume and technologies, but also to investigate the animal species used for the production of skin garments. Until recently, species identification of archaeological skin was primarily performed by light and scanning electron microscopy or the analysis of ancient DNA. However, the efficacy of these methods can be limited due to the harsh, mostly acidic environment of peat bogs leading to morphological and molecular degradation within the samples. We compared species assignment results of twelve archaeological skin samples from Danish bogs using Mass Spectrometry (MS)-based peptide sequencing, against results obtained using light and scanning electron microscopy. While it was difficult to obtain reliable results using microscopy, MS enabled the identification of several species-diagnostic peptides, mostly from collagen and keratins, allowing confident species discrimination even among taxonomically close organisms, such as sheep and goat. Unlike previous MS-based methods, mostly relying on peptide fingerprinting, the shotgun sequencing approach we describe aims to identify the complete extracted ancient proteome, without preselected specific targets. As an example, we report the identification, in one of the samples, of two peptides uniquely assigned to bovine foetal haemoglobin, indicating the production of skin from a calf slaughtered within the first months of its life. We conclude that MS-based peptide sequencing is a reliable method for species identification of samples from bogs. The mass spectrometry proteomics data were deposited in the ProteomeXchange Consortium with the dataset identifier PXD001029. PMID:25260035

SPRUCE Manual Phenology Observations and Photographs Beginning in 2010

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

Heiderman, Ryan R; Nettles, W. Robert; Ontl, Todd A

Periodic observations of the phenology of vegetation bud swell, leaf out, leaf off, flowering, fruiting and the nature of snow cover and ice presence have been assessed by SPRUCE project personnel since 2010. These observations are supplemented by the collection of images from periodic photographs. Annual summaries of vegetation phenology and snow and ice presence are also provided. Early observations were conducted throughout the S1-Bog with an emphasis on the southern end of the bog. Observations collected since the spring of 2013 have focused on the southern end of the S1-Bog and the plots 2 through 21 of the SPRUCEmore » experiment. Beginning in 2015 those observations included assessments within the enclosure space surrounding plots 4, 6, 8, 10, 11, 13, 16, 17, 19 and 20. Newly collected data will be appended annually.« less

A preliminary population study of alcove bog orchid (Platanthera zothecina) at Navajo National Monument, Arizona

Treesearch

Laura E. Hudson

2001-01-01

This study on Platanthera zothecina (alcove bog orchid) was initiated by the National Park Service after a recent threatened and endangered species survey at Navajo National Monument. It is listed as Category 2 (species of special concern) by the U.S. Fish and Wildlife Service, and Category 3 (likely to become endangered) by the Navajo Nation. Because P. zothecina is a...

Hydrologic cycling of mercury and organic carbon in a forested upland-bog watershed

Treesearch

R. K. Kolka; D. F. Grigal; E. A. Nater; E. S. Verry

2001-01-01

The hydrologic cyvling of total Hg (HgT) and organic C (OC) was studies for a 1-yr period in a northern Minnesota forested watershed, consisting of an upland surrounding a bog peatland with a narrow lagg at their interface. Throughfall and sternflow contributed twice as much HgT as seven times as much OC to the forested watershed than atmospheric deposition in a...

Fine-root growth in a forested bog is seasonally dynamic, but shallowly distributed in nutrient-poor peat

DOE PAGES

Iversen, Colleen M.; Childs, Joanne; Norby, Richard J.; ...

2017-03-30

Fine roots contribute to ecosystem carbon, water, and nutrient fluxes through resource acquisition, respiration, exudation, and turnover, but are understudied in peatlands. Here, we aimed to determine how the amount and timing of fine-root growth in a forested, ombrotrophic bog varied across gradients of vegetation density, peat microtopography, and changes in environmental conditions across the growing season and throughout the peat profile. We quantified fine-root peak standing crop and growth using non-destructive minirhizotron technology over a two-year period, focusing on the dominant woody species in the bog: Picea mariana, Larix laricina, Rhododendron groenlandicum, and Chamaedaphne calyculata. The fine roots ofmore » trees and shrubs were concentrated in raised hummock microtopography, with more tree roots associated with greater tree densities and a unimodal peak in shrub roots at intermediate tree densities. Fine-root growth tended to be seasonally dynamic, but shallowly distributed, in a thin layer of nutrient-poor, aerobic peat above the growing season water table level. Finally, the dynamics and distribution of fine roots in this forested ombrotrophic bog varied across space and time in response to biological, edaphic, and climatic conditions, and we expect these relationships to be sensitive to projected environmental changes in northern peatlands.« less

Numerical study of heat transfer characteristics in BOG heat exchanger

NASA Astrophysics Data System (ADS)

Yan, Yan; Pfotenhauer, John M.; Miller, Franklin; Ni, Zhonghua; Zhi, Xiaoqin

2016-12-01

In this study, a numerical study of turbulent flow and the heat transfer process in a boil-off liquefied natural gas (BOG) heat exchanger was performed. Finite volume computational fluid dynamics and the k - ω based shear stress transport model were applied to simulate thermal flow of BOG and ethylene glycol in a full-sized 3D tubular heat exchanger. The simulation model has been validated and compared with the engineering specification data from its supplier. In order to investigate thermal characteristics of the heat exchanger, velocity, temperature, heat flux and thermal response were studied under different mass flowrates in the shell-side. The shell-side flow pattern is mostly determined by viscous forces, which lead to a small velocity and low temperature buffer area in the bottom-right corner of the heat exchanger. Changing the shell-side mass flowrate could result in different distributions of the shell-side flow. However, the distribution in the BOG will remain in a relatively stable pattern. Heat flux increases along with the shell-side mass flowrate, but the increase is not linear. The ratio of increased heat flux to the mass flow interval is superior at lower mass flow conditions, and the threshold mass flow for stable working conditions is defined as greater than 0.41 kg/s.

Fine-root growth in a forested bog is seasonally dynamic, but shallowly distributed in nutrient-poor peat

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

Iversen, Colleen M.; Childs, Joanne; Norby, Richard J.

Fine roots contribute to ecosystem carbon, water, and nutrient fluxes through resource acquisition, respiration, exudation, and turnover, but are understudied in peatlands. Here, we aimed to determine how the amount and timing of fine-root growth in a forested, ombrotrophic bog varied across gradients of vegetation density, peat microtopography, and changes in environmental conditions across the growing season and throughout the peat profile. We quantified fine-root peak standing crop and growth using non-destructive minirhizotron technology over a two-year period, focusing on the dominant woody species in the bog: Picea mariana, Larix laricina, Rhododendron groenlandicum, and Chamaedaphne calyculata. The fine roots ofmore » trees and shrubs were concentrated in raised hummock microtopography, with more tree roots associated with greater tree densities and a unimodal peak in shrub roots at intermediate tree densities. Fine-root growth tended to be seasonally dynamic, but shallowly distributed, in a thin layer of nutrient-poor, aerobic peat above the growing season water table level. Finally, the dynamics and distribution of fine roots in this forested ombrotrophic bog varied across space and time in response to biological, edaphic, and climatic conditions, and we expect these relationships to be sensitive to projected environmental changes in northern peatlands.« less

Evaluation of heavy metal pollution in bogs of Tomsk region on change in biogeochemical activity of ericaceous shrubs

NASA Astrophysics Data System (ADS)

Gaskova, L. P.

2018-01-01

The article discusses the change in biogeochemical activity of plant species in bogs under the influence of various types of human impact (roads, cities, drainage of mires, fire). It has been established that ericaceous shrubs, depending on the species, react with varying degrees of intensity to anthropogenic influences. The biogeochemical activity of species increased by 2.5 to 4.8 times in polluted sites.

Differential effects of high atmospheric N and S deposition on bog plant/lichen tissue and porewater chemistry across the Athabasca Oil Sands Region

Treesearch

R. Kelman Wieder; Melanie A. Vile; Kimberli D. Scott; Cara M. Albright; Kelly J. McMillen; Dale H. Vitt; Mark E. Fenn

2016-01-01

Oil extraction and development activities in the Athabasca Oil Sands Region of northern Alberta, Canada, release NOx, SOx, and NHy to the atmosphere, ultimately resulting in increasing N and S inputs to surrounding ecosystems through atmospheric deposition. Peatlands are a major feature of the northern Alberta landscape, with bogs covering 6-10% of the land area, and...

The Effect of Overstory Removal Upon Surface WInd in a Black Spruce Bog

Treesearch

James M. Brown

1972-01-01

Wind passage was measured over a black spruce canopy, at the surface under the canopy, and in a clearcut strip in a northern Minnesota bog. During a 40-day period wind below the canopy was 10 percent of that above the canopy while the wind in the clearcut strip was 45 percent of the total above the canopy. Wind at the surface of the clearcut strip was of longer...

SPRUCE S1 Bog Tree Basal Area and Understory Community Composition Assessed in the Southern and Northern Ends of the S1 Bog

DOE Data Explorer

Iversen, C. M. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A; Garrett, A. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A; Martin, A. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A; Turetsky, M. R. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A; Norby, R. J. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A; Childs, J. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A; Ontl, T. A. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A

2017-01-01

The composition and cover of woody and understory species, along with the timing of stem growth, were characterized near minirhizotron installations at the south and north ends of the S1 bog in order to understand the relationship between root dynamics and the surrounding plant communities. There are three data streams: (1) Woody species basal area -- the number, basal area, and distance from the center point of all trees within a 5-m radius of each minirhizotron pair, which were quantified in 2011, (2) Understory cover -- the understory vascular plant community composition and percent cover, which were surveyed in 1 m2 areas at four cardinal directions adjacent to each pair of minirhizotrons in June 2011, and (3) Stem growth -- the basal area increment (stem growth) of nearby trees, which was quantified using automated or manual dendrobands in 2011 and 2012, respectively.

Effects of experimental nitrogen deposition on peatland carbon pools and fluxes: a modelling analysis

NASA Astrophysics Data System (ADS)

Wu, Y.; Blodau, C.; Moore, T. R.; Bubier, J.; Juutinen, S.; Larmola, T.

2015-01-01

Nitrogen (N) pollution of peatlands alters their carbon (C) balances, yet long-term effects and controls are poorly understood. We applied the model PEATBOG to explore impacts of long-term nitrogen (N) fertilization on C cycling in an ombrotrophic bog. Simulations of summer gross ecosystem production (GEP), ecosystem respiration (ER) and net ecosystem exchange (NEE) were evaluated against 8 years of observations and extrapolated for 80 years to identify potential effects of N fertilization and factors influencing model behaviour. The model successfully simulated moss decline and raised GEP, ER and NEE on fertilized plots. GEP was systematically overestimated in the model compared to the field data due to factors that can be related to differences in vegetation distribution (e.g. shrubs vs. graminoid vegetation) and to high tolerance of vascular plants to N deposition in the model. Model performance regarding the 8-year response of GEP and NEE to N input was improved by introducing an N content threshold shifting the response of photosynthetic capacity (GEPmax) to N content in shrubs and graminoids from positive to negative at high N contents. Such changes also eliminated the competitive advantages of vascular species and led to resilience of mosses in the long-term. Regardless of the large changes of C fluxes over the short-term, the simulated GEP, ER and NEE after 80 years depended on whether a graminoid- or shrub-dominated system evolved. When the peatland remained shrub-Sphagnum-dominated, it shifted to a C source after only 10 years of fertilization at 6.4 g N m-2 yr-1, whereas this was not the case when it became graminoid-dominated. The modelling results thus highlight the importance of ecosystem adaptation and reaction of plant functional types to N deposition, when predicting the future C balance of N-polluted cool temperate bogs.

Changes in dissolved organic matter quality in a peatland and forest headwater stream as a function of seasonality and hydrologic conditions

NASA Astrophysics Data System (ADS)

Broder, Tanja; Knorr, Klaus-Holger; Biester, Harald

2017-04-01

Peatlands and peaty riparian zones are major sources of dissolved organic matter (DOM), but are poorly understood in terms of export dynamics and controls thereof. Thereby quality of DOM affects function and behavior of DOM in aquatic ecosystems, but DOM quality can also help to track DOM sources and their export dynamics under specific hydrologic preconditions. The objective of this study was to elucidate controls on temporal variability in DOM concentration and quality in stream water draining a bog and a forested peaty riparian zone, particularly considering drought and storm flow events. DOM quality was monitored using spectrofluorometric indices for aromaticity (SUVA254), apparent molecular size (SR) and precursor organic material (FI), as well as PARAFAC modeling of excitation emission matrices (EEMs). Indices for DOM quality exhibited major changes due to different hydrologic conditions, but patterns were also dependent on season. Stream water at the forested site with mineral, peaty soils generally exhibited higher variability in DOM concentrations and quality compared to the outflow of an ombrotrophic bog, where DOM was less susceptible to changes in hydrologic conditions. During snowmelt and spring events, near-surface protein-like DOM pools were exported. A microbial DOM fraction originating from groundwater and deep peat layers was increasing during drought, while a strongly microbially altered DOM fraction was also exported by discharge events with dry preconditions at the forested site. This might be due to accelerated microbial activity in the peaty riparian zone of the forested site under these preconditions. Our study demonstrated that DOM export dynamics are not only a passive mixing of different hydrological sources, but monitoring studies have to consider that DOM quality depends on hydrologic preconditions and season. Moreover, the forested peaty riparian zone generated the most variability in headwater DOM quantity and quality, as could be tracked by the used spectrofluorometric indices.

Association between obesity and various parameters of physical fitness in Korean students.

PubMed

Kim, Jae-Woo; Seo, Dong-Il; Swearingin, B; So, Wi-Young

2013-01-01

The purpose of this study was to evaluate the association between the types of obesity classified according to the body mass index (BMI) and/or waist circumference (WC) and the various parameters of physical fitness in Korean college students. BMI, WC, and fitness assessments were performed on 726 male college student volunteers who visited a public health center in Seoul, Korea. Classification based on BMI and/or WC was established according to the data in the WHO's Asia-Pacific standard report, and the subjects were divided into the following 4 groups: (1) obese as determined by BMI, but not WC (BMI Obesity Group, BOG); (2) obese as determined by WC, but not BMI (WC Obesity Group, WOG); (3) obese as determined by both BMI and WC (BWOG); and (4) non-obese normal group (NG). Fitness assessment parameters such as cardiorespiratory endurance, cardiovascular function, muscular endurance, muscular strength, flexibility, power, agility, and balance were evaluated through the following measurements: time required to run 1.5 km, physical efficiency index (PEI), vital capacity (ℓ), push-ups (reps/2 min), sit-ups (reps/2 min), back strength (kg), grip strength (kg), sit and reach distance (cm), vertical jumps (cm), whole body reaction time (ms), side steps (reps/30 s), and maximum time of standing on 1 foot with closed eyes (s). The odds ratios (OR) (95% confidence interval [CI]) of the BOG and WOG for the 1.5-km run were 0.367 (0.192-0.701) and 0.168 (0.037-0.773), respectively; of the BWOG and WOG for vital capacity were 5.900 (1.298-26.827) and 5.364 (1.166-24.670), respectively; of the BOG for push-ups was 0.517 (0.279-0.959); of the WOG for back strength was 0.206 (0.045-0.945); of the BWOG and BOG for grip strength were 5.973 (1.314-27.157) and 2.036 (1.089-3.807), respectively; and of the BOG for the whole body reaction time was 0.405 (0.212-0.774), as compared to the NG. We conclude that all 3 types of obesity (classified into the BWOG, BOG, and WOG) result in reduced cardiorespiratory and muscular endurance, but increased muscular strength and vital capacity. © 2013 Asian Oceanian Association for the Study of Obesity . All rights reserved.

Geomorphology and landscape organization of a northern peatland complex

NASA Astrophysics Data System (ADS)

Richardson, M. C.

2012-12-01

The geomorphic evolution of northern peatlands is governed by complex ecohydrological feedback mechanisms and associated hydro-climatic drivers. For example, prevailing models of bog development (i.e. Ingram's groundwater mounding hypothesis and variants) attempt to explicitly link bog dome characteristics to the regional climate based on analytical and numerical models of lateral groundwater flow and the first-order control of water table position on rates of peat accumulation. In this talk I will present new results from quantitative geomorphic analyses of a northern peatland complex at the De Beers Victor diamond mine site in the Hudson Bay Lowlands of northern Ontario. This work capitalizes on spatially-extensive, high-resolution topographic (LiDAR) data to rigorously test analytical and numerical models of bog dome development in this landscape. The analysis and discussion are then expanded beyond individual bog formations to more broadly consider ecohydrological drivers of landscape organization, with implications for understanding and modeling catchment-scale runoff response. Results show that in this landscape, drainage patterns exhibit relatively well-organized characteristics consistent with observed runoff responses in six gauged research catchments. Interpreted together, the results of these geomorphic and hydrologic analyses help refine our understanding of water balance partitioning among different landcover types within northern peatland complexes. These findings can be used to help guide the development of appropriate numerical model structures for hydrologic prediction in ungauged peatland basins of northern Canada.

A new boil-off gas re-liquefaction system for LNG carriers based on dual mixed refrigerant cycle

NASA Astrophysics Data System (ADS)

Tan, Hongbo; Shan, Siyu; Nie, Yang; Zhao, Qingxuan

2018-06-01

A new boil-off gas (BOG) re-liquefaction system for LNG carriers has been proposed to improve the system energy efficiency. Two cascade mixed refrigerant cycles (or dual mixed refrigerant cycle, DMR) are used to provide the cooling capacity for the re-liquefaction of BOG. The performance of the new system is analysed on the basis of the thermodynamic data obtained in the process simulation in Aspen HYSYS software. The results show that the power consumed in the BOG compressor and the high-temperature mixed refrigerant compressor could be saved greatly due to the reduced mass flow rates of the processed fluids. Assuming the re-liquefaction capacity of the investigated system is 4557.6 kg/h, it is found that the total power consumption can be reduced by 25%, from 3444 kW in the existing system to 2585.8 kW in the proposed system. The coefficient of performance (COP) of 0.25, exergy efficiency of 41.3% and the specific energy consumption (SEC) of 0.589 kWh/kg(LNG) could be achieved in the new system. It exhibits 33% of improvement in the COP and exergy efficiency in comparison with the corresponding values of the existing system. It indicates that employing the DMR based BOG re-liquefaction system could improve the system energy efficiency of LNG carriers substantially.

Bottlenecks in bog pine multiplication by somatic embryogenesis and their visualization with the environmental scanning electron microscope.

PubMed

Vlašínová, Helena; Neděla, Vilem; Đorđević, Biljana; Havel, Ladislav

2017-07-01

Somatic embryogenesis (SE) is an important biotechnological technique used for the propagation of many pine species in vitro. However, in bog pine, one of the most endangered tree species in the Czech Republic, limitations were observed, which negatively influenced the development and further germination of somatic embryos. Although initiation frequency was very low-0.95 %, all obtained cell lines were subjected to maturation. The best responding cell line (BC1) was used and subjected to six different variants of the maturation media. The media on which the highest number of early-precotyledonary/cotyledonary somatic embryos was formed was supplemented with 121 μM abscisic acid (ABA) and with 6 % maltose. In the end of maturation experiments, different abnormalities in formation of somatic embryos were observed. For visualization and identification of abnormalities in meristem development during proliferation and maturation processes, the environmental scanning electron microscope was used. In comparison to the classical light microscope, the non-commercial environmental scanning electron microscope AQUASEM II has been found as a very useful tool for the quick recognition of apical meristem disruption and abnormal development. To our knowledge, this is the first report discussing somatic embryogenesis in bog pine. Based on this observation, the cultivation procedure could be enhanced and the method for SE of bog pine optimized.

A Record of Moisture History in Hawaii since the Arrival of Humans Inferred from Testate Amoebae and Cladocera Fossils Preserved in Bog Sediments

NASA Astrophysics Data System (ADS)

Barrett, K.; Kim, S. H.; Hotchkiss, S.

2015-12-01

Around AD 800, Polynesians arrived on the Hawaiian Islands where they expanded and intensified distinct agricultural practices in the islands' wet and dry regions. Dryland farming productivity in particular would have been sensitive to atmospheric rearrangements of the ENSO and PDO systems that affect rainfall in Hawaii. The few detailed terrestrial paleoclimate records in Hawaii are mainly derived from vegetation proxies (e.g. pollen, seeds, fruits, and plant biomarkers) which are heavily influenced by widespread landscape modification following human arrival. Here we present initial results of an independent paleomoisture proxy: fossil remains of moisture-sensitive testate amoebae (Protozoa: Rhizopoda) and cladocera (water fleas) preserved in continuous bog sediments on Kohala Volcano uplsope of the ancient Kohala agricultural field system, one of the largest dryland field systems in Hawaii. Hydrologic conditions inferred from testate amoebae and cladoceran fossil assemblages correlate with observed decadal moisture regimes in Hawaii and state changes of the PDO system during the last century. Testate ameoabe and cladoceran fossils in older sediments reveal an alternating history of very wet, lake-forming conditions on the bog surface to periods when bog soils were much drier than today's, demonstrating that this method can be paired with vegetation proxies to provide a better understanding of hydroclimate variability in prehistoric Hawaii.

The effects of music listening after a stressful task on immune functions, neuroendocrine responses, and emotional states in college students.

PubMed

Hirokawa, Eri; Ohira, Hideki

2003-01-01

The purpose of this study was to examine the effects of listening to high-uplifting or low-uplifting music after a stressful task on (a) immune functions, (b) neuroendocrine responses, and (c) emotional states in college students. Musical selections that were evaluated as high-uplifting or low-uplifting by Japanese college students were used as musical stimuli. Eighteen Japanese subjects performed stressful tasks before they experienced each of these experimental conditions: (a) high-uplifting music, (b) low-uplifting music, and (c) silence. Subjects' emotional states, the Secretory IgA (S-IgA) level, active natural killer (NK) cell level, the numbers of T lymphocyte CD4+, CD8+, CD16+, dopamine, norepinephrine, and epinephrine levels were measured before and after each experimental condition. Results indicated low-uplifting music had a trend of increasing a sense of well-being. High-uplifting music showed trends of increasing the norepinephrine level, liveliness, and decreasing depression. Active NK cells were decreased after 20 min of silence. Results of the study were inconclusive, but high-uplifting and low-uplifting music had different effects on immune, neuroendocrine, and psychological responses. Classification of music is important to research that examines the effects of music on these responses. Recommendations for future research are discussed.

Biological N2 fixation mainly controlled by Sphagnum tissue N:P ratio in ombrotrophic bogs

NASA Astrophysics Data System (ADS)

Zivkovic, Tatjana; Moore, Tim R.

2017-04-01

Most of the 18 Pg nitrogen (N) accumulated in northern nutrient-poor and Sphagnum-dominated peatlands (bogs and fens) can be attributed to N2-fixation by diazotrophs either associated with the live Sphagnum or non-symbiotically in the deeper peat such as through methane consumption close to the water table. Where atmospheric N deposition is low (< 0.2 g m-2 y-1), ombrotrophic bogs rely on N2-fixation as the primary source of N that sustains primary production. Due to high energetic requirements, N2-fixation depends on the available phosphorus (P). Anthropogenic impacts in the last 200 years increased atmospheric N deposition, resulting in a switch from N to P limitation in Sphagnum, suggested by the increase in tissue N:P to >16. It is unclear how Sphagnum-hosted diazotrophic activity may be affected by N deposition and thus changes in N:P ratio. First, we investigated the effects of long-term addition of different sources of nitrogen (0, 1.6, 3.2 and 6.4 g N m-2 y-1as NH4Cl and NaNO3), and phosphorus (5 g P m-2 y-1as KH2PO4) on Sphagnum nutrient status (N, P and N:P ratio), net primary productivity (NPP) and Sphagnum-associated N2fixation at Mer Bleue, a temperate ombrotrophic bog. We show that N concentration in Sphagnum tissue increased with larger rates of N addition, with a stronger effect on Sphagnum from NH4 than NO3. The addition of P created a 3.5 fold increase in Sphagnum P content compared to controls. Sphagnum NPP decreased linearly with the rise in N:P ratio, while linear growth declined exponentially with increase in Sphagnum N content. Rates of N2-fixation determined in the laboratory significantly decreased in response to even the smallest addition of both N species. In contrast, the addition of P increased N2 fixation by up to 100 times compared to N treatments and up to 5-30 times compared to controls. The change in N2-fixation was best modeled by the N:P ratio, across all experimental treatments. Secondly, to test the role of N:P ratio on N2-fixation across a range of bogs, eight study sites along the latitudinal gradient from temperate, boreal to subarctic zone in eastern Canada were selected. From each bog, two predominant microptopographies, hummocks and hollows, were tested for both N2-fixation activity in the laboratory and Sphagnum tissue concentrations of N, P and N:P ratio. We found that 65% of the variance in the increase of N2-fixation activity was explained by the decrease in N:P ratio in hollows (n = 73) but only about 20% in hummocks (n = 78). Changes in neither N or P concentration alone explained the increase in N2-fixation better than N:P ratio. We interpret that the difference between hollows and hummocks results from the availability of moisture that further limits N2-fixation. When moisture is not a limiting factor, i.e. in hollows, N:P ratio will be the best predictor of N2-fixation in bogs. Both studies suggest that the relative P availability to Sphagnum-associated diazotrophs, measured as a tissue N:P ratio, best describes N2-fixation activity in bogs, especially ones exposed to larger N deposition.

Carbon budget of oligotrophic mires in the Southern Taiga of Western Siberia under anthropogenic impact

NASA Astrophysics Data System (ADS)

Golovatskaya, Eugenia; Dyukarev, Egor

2010-05-01

Role of peatlands in the global greenhouse gases budget is highly relevant. According to present estimates peatlands in undisturbed conditions act as a sink for the atmospheric carbon. Anthropogenic impact on peatlands (melioration, changes in land use, influence of underground water catchments) results in water table lowering, changing in vegetation cover, and degradation of peat deposit. Peatlands could provide a significant positive feedback for climate changes if warming and peatlands drying stimulates bulk soil organic matter decomposition which enhances CO2 release to the atmosphere. Western Siberian peatlands usually represented big bog massifs. Big peatlands have higher stability to external influence. Small peatlands have all signs of big bogs but react on changes in environmental variables more quickly. The present study is devoted to investigation of primary carbon fluxes (CO2 emission and net primary productivity) and carbon balance at oligotrophic bogs in native condition (key area "Bakchar") and under anthropogenic impact (key area "Ob'-Tom'"). The key area "Bakchar" is located between the Iksa and Bakchar rivers (56o58`N 82o36`E) at the Bakcharskoe bog (area 1400 km2). The key area "Ob'-Tom'"is located in the northern part of Ob' and Tom' interfluve (56o21`N 82o31`E). The "Bakchar" key area includes the following ecosystems: pine- shrub-sphagnum community, a similar community with stunted (low) pine trees, and sedge-sphagnum fen. Two small peatlands were studied at Ob' and Tom' interfluve. Kirsanovskoe bog includes pine- shrub-sphagnum community and sedge fen. Timiryazevskoe bog was represented by pine- shrub-sphagnum (TPSS) community and sedge fen. An infrared gas analyzer OPTOGAS 500.4 (OPTEC Corp., St.-Petersburg, Russia) attached to a static opaque plastic been used for carbon dioxide emission measurements. The net primary productivity was measured by clipping method (Golovatskaya and Dyukarev, Plant Soil 2009). Peatlands at "Ob'-Tom'" key area are under impact of water catchments for Tomsk city supply. Changes in deep waters results in changes of hydrological regime and environment transformations. Water level drawdown leads to increase of aerobic layer thickness, intensification of plant remains decomposition, peat layers compacting and rises of CO2 emission from the surface. Carbon dioxide emission from bogs of "Ob'-Tom'" key area is about two times higher than emission from pristine bogs ("Bakchar" key area). Aboveground net primary productivity determined without tree layer at all studied peatlands has similar values. Belowground net primary productivity at "Ob'-Tom'" key area if 4-7 times higher than at "Bakchar" key area depending on the ecosystem type. An essential increase in root density after water level depletion results in increase on total net productivity by 2.4 times. Carbon budget for pristine peatlands ("Bakchar" key area) varies from 27 (open fen) to 46 (low ryam) gC/m2/yr. Peatlands of "Ob'-Tom'" key area accumulates about 210 gC/m2/yr in average. Our observations of the elements of carbon exchange have shown that at present all studied peatlands act as carbon sinks. Long-term water table lowering at least at first stage stipulates carbon removing from the atmosphere and accumulation in a form of peat. Work was partially supported by Russian Fund of Basic Researches (08-05-00426/a, 08-05-92501).

Landscape analysis of nutrient-enriched margins (lagg) in ombrotrophic peatlands.

PubMed

Langlois, Mélanie N; Price, Jonathan S; Rochefort, Line

2015-02-01

Scientific knowledge of the wet zone - the lagg - that tends to form at the edge of ombrotrophic peatlands is surprisingly limited. In this study, we aim to improve the understanding of the ecohydrological functions of this transition by describing the form and abiotic controls of the laggs and margins of bog peatlands. Data collected in wells and piezometers along 10 transects (within 6 bogs), of the New Brunswick Eastern Lowlands are used to analyse the hydraulic and hydrochemical gradients, while airborne LiDAR data provides new insight on the geomorphology and the vegetation patterns of the bog-lagg-mineral transition zone. Based on their geomorphic character, the study transects are placed into 2 categories: confined and unconfined. Laggs of confined transition are found in a topographic depression, between the bog and a mineral slope >1%, while laggs of unconfined transitions are adjacent to a flat (≤1%) or receding mineral slope (sloping away from the lagg). Water level (4 ± 9 cm vs. -3 ± 9 cm), pH (4.8 ± 0.9 vs. 4.2 ± 0.4), electrical conductivity (ECcorr) (105 ± 52 μS cm(-1) vs. 52 ± 28 μS cm(-1)) and peat depth (55 ± 9 cm vs. 30 ± 9 cm) are found to be higher, respectively, for the confined laggs than for the unconfined. Saturated hydraulic conductivity (Ksat) of the lagg's upper peat layer resembles that of bog environments, but quickly reduces with depth, impeding vertical water flow. The greatest abiotic control of the lagg appears to be topography, which affects water flow rates and direction, thus water chemistry, nutrient transport and availability, hence vegetation characteristics. Our results suggest that the features of the transition zone that include the lagg, influence the quantity and variability of water within the adjacent peatland, and should be considered as integral part of the peatland complex. Copyright © 2014 Elsevier B.V. All rights reserved.

Investigating the Influence of Vegetation Type on Modern Leaf Wax Hydrogen Isotopes from a High Latitude Ombrotrophic Bog to Inform Paleoclimate Interpretation

NASA Astrophysics Data System (ADS)

Balascio, N.; D'Andrea, W. J.; Anderson, R. S.

2016-12-01

Leaf wax hydrogen isotopes have been used to track changes in the isotopic composition of meteoric waters in a variety of locations. However, leaf wax compounds preserved in sedimentary environments reflect a mix of plant sources that can have a large range of molecular distributions and biosynthetic fractionation factors potentially complicating paleoclimate interpretations. Here we attempt to constrain the influence of vegetation type on leaf wax hydrogen isotope values at an ombrotrophic bog in northern Norway. We present: (i) δD values of n-alkanes from modern bog vegetation to establish the influence of vegetation type on n-alkane distributions and to provide a site-specific assessment of the biosynthetic isotopic fractionation, and (ii) δD values of n-alkanes from a sediment core spanning the last 10 ka where vegetation changes have been reconstructed based on pollen analysis. We found 14 different vegetation types growing on the bog surface that have average chain lengths from 25 to 30.5 and δD values of n-C25 to n-C33 ranging from -197‰ to -116‰. These samples also have a range of δD values among n-alkane homologues, from 1‰ to 33‰. Based on isotopic measurements of modern bog water, we calculate the average apparent fractionation of n-alkanes to be -108 ± 22‰. Sedimentary δD values of n-C25 to n-C33 over the last 10 ka range from -229 to -158‰ with distinct trends among mid- and long-chain length homologues. Changes in chain lengths and δD values, at times, correspond to vegetation shifts documented by pollen data, but also show unique trends that we interpret to represent variations in local precipitation isotopes related to past hydroclimate change.

Untangling climatic and autogenic signals in peat records

NASA Astrophysics Data System (ADS)

Morris, Paul J.; Baird, Andrew J.; Young, Dylan M.; Swindles, Graeme T.

2016-04-01

Raised bogs contain potentially valuable information about Holocene climate change. However, autogenic processes may disconnect peatland hydrological behaviour from climate, and overwrite and degrade climatic signals in peat records. How can genuine climate signals be separated from autogenic changes? What level of detail of climatic information should we expect to be able to recover from peat-based reconstructions? We used an updated version of the DigiBog model to simulate peatland development and response to reconstructed Holocene rainfall and temperature reconstructions. The model represents key processes that are influential in peatland development and climate signal preservation, and includes a network of feedbacks between peat accumulation, decomposition, hydraulic structure and hydrological processes. It also incorporates the effects of temperature upon evapotranspiration, plant (litter) productivity and peat decomposition. Negative feedbacks in the model cause simulated water-table depths and peat humification records to exhibit homeostatic recovery from prescribed changes in rainfall, chiefly through changes in drainage. However, the simulated bogs show less resilience to changes in temperature, which cause lasting alterations to peatland structure and function and may therefore be more readily detectable in peat records. The network of feedbacks represented in DigiBog also provide both high- and low-pass filters for climatic information, meaning that the fidelity with which climate signals are preserved in simulated peatlands is determined by both the magnitude and the rate of climate change. Large-magnitude climatic events of an intermediate frequency (i.e., multi-decadal to centennial) are best preserved in the simulated bogs. We found that simulated humification records are further degraded by a phenomenon known as secondary decomposition. Decomposition signals are consistently offset from the climatic events that generate them, and decomposition records of dry-wet-dry climate sequences appear to be particularly vulnerable to overwriting. Our findings have direct implications not only for the interpretation of peat-based records of past climates, but also for understanding the likely vulnerability of peatland ecosystems and carbon stocks to future climate change.

Representing northern peatland microtopography and hydrology within the Community Land Model

DOE PAGES

Shi, Xiaoying; Thornton, Peter E.; Ricciuto, Daniel M.; ...

2015-11-12

Predictive understanding of northern peatland hydrology is a necessary precursor to understanding the fate of massive carbon stores in these systems under the influence of present and future climate change. Current models have begun to address microtopographic controls on peatland hydrology, but none have included a prognostic calculation of peatland water table depth for a vegetated wetland, independent of prescribed regional water tables. We introduce here a new configuration of the Community Land Model (CLM) which includes a fully prognostic water table calculation for a vegetated peatland. Our structural and process changes to CLM focus on modifications needed to representmore » the hydrologic cycle of bogs environment with perched water tables, as well as distinct hydrologic dynamics and vegetation communities of the raised hummock and sunken hollow microtopography characteristic of peatland bogs. The modified model was parameterized and independently evaluated against observations from an ombrotrophic raised-dome bog in northern Minnesota (S1-Bog), the site for the Spruce and Peatland Responses Under Climatic and Environmental Change experiment (SPRUCE). Simulated water table levels compared well with site-level observations. The new model predicts hydrologic changes in response to planned warming at the SPRUCE site. At present, standing water is commonly observed in bog hollows after large rainfall events during the growing season, but simulations suggest a sharp decrease in water table levels due to increased evapotranspiration under the most extreme warming level, nearly eliminating the occurrence of standing water in the growing season. Simulated soil energy balance was strongly influenced by reduced winter snowpack under warming simulations, with the warming influence on soil temperature partly offset by the loss of insulating snowpack in early and late winter. Furthermore, the new model provides improved predictive capacity for seasonal hydrological dynamics in northern peatlands, and provides a useful foundation for investigation of northern peatland carbon exchange.« less

Representing northern peatland microtopography and hydrology within the Community Land Model

DOE PAGES

Shi, X.; Thornton, P. E.; Ricciuto, D. M.; ...

2015-02-20

Predictive understanding of northern peatland hydrology is a necessary precursor to understanding the fate of massive carbon stores in these systems under the influence of present and future climate change. Current models have begun to address microtopographic controls on peatland hydrology, but none have included a prognostic calculation of peatland water table depth for a vegetated wetland, independent of prescribed regional water tables. We introduce here a new configuration of the Community Land Model (CLM) which includes a fully prognostic water table calculation for a vegetated peatland. Our structural and process changes to CLM focus on modifications needed to representmore » the hydrologic cycle of bogs environment with perched water tables, as well as distinct hydrologic dynamics and vegetation communities of the raised hummock and sunken hollow microtopography characteristic of peatland bogs. The modified model was parameterized and independently evaluated against observations from an ombrotrophic raised-dome bog in northern Minnesota (S1-Bog), the site for the Spruce and Peatland Responses Under Climatic and Environmental Change experiment (SPRUCE). Simulated water table levels compared well with site-level observations. The new model predicts significant hydrologic changes in response to planned warming at the SPRUCE site. At present, standing water is commonly observed in bog hollows after large rainfall events during the growing season, but simulations suggest a sharp decrease in water table levels due to increased evapotranspiration under the most extreme warming level, nearly eliminating the occurrence of standing water in the growing season. Simulated soil energy balance was strongly influenced by reduced winter snowpack under warming simulations, with the warming influence on soil temperature partly offset by the loss of insulating snowpack in early and late winter. The new model provides improved predictive capacity for seasonal hydrological dynamics in northern peatlands, and provides a useful foundation for investigation of northern peatland carbon exchange.« less

Ferricrete, manganocrete, and bog iron occurrences with selected sedge bogs and active iron bogs and springs in the upper Animas River watershed, San Juan County, Colorado

USGS Publications Warehouse

Yager, Douglas B.; Church, Stan E.; Verplanck, Philip L.; Wirt, Laurie

2003-01-01

During 1996 to 2000, the Bureau of Land Management, National Park Service, Environmental Protection Agency, United States Department of Agriculture (USDA) Forest Service, and the U.S. Geological Survey (USGS) developed a coordinated strategy to (1) study the environmental effects of historical mining on Federal lands, and (2) remediate contaminated sites that have the greatest impact on water quality and ecosystem health. This dataset provides information that contributes to these overall objectives and is part of the USGS Abandoned Mine Lands Initiative. Data presented here represent ferricrete occurrences and selected iron bogs and springs in the upper Animas River watershed in San Juan County near Silverton, Colorado. Ferricretes (stratified iron and manganese oxyhydroxide-cemented sedimentary deposits) are one indicator of the geochemical baseline conditions as well as the effect that weathering of mineralized rocks had on water quality in the Animas River watershed prior to mining. Logs and wood fragments preserved in several ferricretes in the upper Animas River watershed, collected primarily along streams, yield radiocarbon ages of modern to 9,580 years B.P. (P.L. Verplanck, D.B. Yager, and S.E. Church, work in progress). The presence of ferricrete deposits along the current stream courses indicates that climate and physiography of the Animas River watershed have been relatively constant throughout the Holocene and that weathering processes have been ongoing for thousands of years prior to historical mining activities. Thus, by knowing where ferricrete is preserved in the watershed today, land-management agencies have an indication of (1) where metal precipitation from weathering of altered rocks has occurred in the past, and (2) where this process is ongoing and may confound remediation efforts. These data are included as two coverages-a ferricrete coverage and a bogs and springs coverage. The coverages are included in ArcInfo shapefile and ArcInfo interchange file format.

Contrasting perspectives on the Lava Creek Tuff eruption, Yellowstone, from new U–Pb and 40Ar/39Ar age determinations

USGS Publications Warehouse

Wilson, Colin J. N.; Stelten, Mark; Lowenstern, Jacob B.

2018-01-01

The youngest major caldera-forming event at Yellowstone was the ~ 630-ka eruption of the Lava Creek Tuff. The tuff as mapped consists of two major ignimbrite packages (members A and B), linked to widespread coeval fall deposits and formation of the Yellowstone Caldera. Subsequent activity included emplacement of numerous rhyolite flows and domes, and development of two structurally resurgent domes (Mallard Lake and Sour Creek) that accommodate strain due to continual uplift/subsidence cycles. Uplifted lithologies previously mapped on and adjacent to Sour Creek dome were thought to include the ~ 2.08-Ma Huckleberry Ridge Tuff, cropping out beneath Lava Creek Tuff members A and B. Mapped outcrops of this Huckleberry Ridge Tuff material were sampled as welded ignimbrite (sample YR345) on Sour Creek dome, and at nearby Bog Creek as welded ignimbrite (YR311) underlain by an indurated lithic lag breccia containing blocks of another welded ignimbrite (YR324). Zircon near-rim U–Pb analyses from these samples yield weighted mean ages of 661 ± 13 ka (YR345: 95% confidence), 655 ± 11 ka (YR311), and 664 ± 15 ka (YR324) (combined weighted mean of 658.8 ± 6.6 ka). We also studied two samples of ignimbrite previously mapped as Huckleberry Ridge Tuff on the northeastern perimeter of the Yellowstone Caldera, ~ 12 km ENE of Sour Creek dome. Sanidines from these samples yield 40Ar/39Ar age estimates of 634.5 ± 6.8 ka (8YC-358) and 630.9 ± 4.1 ka (8YC-359). These age data show that all these units represent previously unrecognized parts of the Lava Creek Tuff and do not have any relationship to the Huckleberry Ridge Tuff. Our observations and data imply that the Lava Creek eruption was more complex than is currently assumed, incorporating two tuff units additional to those currently mapped, and which themselves are separated by a time break sufficient for cooling and some reworking. The presence of a lag breccia suggests that a source vent lay nearby (< ~ 3 km) for some of the tuffs and that the Yellowstone Caldera boundary in this area could be reconsidered.

Contrasting perspectives on the Lava Creek Tuff eruption, Yellowstone, from new U-Pb and 40Ar/39Ar age determinations

NASA Astrophysics Data System (ADS)

Wilson, Colin J. N.; Stelten, Mark E.; Lowenstern, Jacob B.

2018-06-01

The youngest major caldera-forming event at Yellowstone was the 630-ka eruption of the Lava Creek Tuff. The tuff as mapped consists of two major ignimbrite packages (members A and B), linked to widespread coeval fall deposits and formation of the Yellowstone Caldera. Subsequent activity included emplacement of numerous rhyolite flows and domes, and development of two structurally resurgent domes (Mallard Lake and Sour Creek) that accommodate strain due to continual uplift/subsidence cycles. Uplifted lithologies previously mapped on and adjacent to Sour Creek dome were thought to include the 2.08-Ma Huckleberry Ridge Tuff, cropping out beneath Lava Creek Tuff members A and B. Mapped outcrops of this Huckleberry Ridge Tuff material were sampled as welded ignimbrite (sample YR345) on Sour Creek dome, and at nearby Bog Creek as welded ignimbrite (YR311) underlain by an indurated lithic lag breccia containing blocks of another welded ignimbrite (YR324). Zircon near-rim U-Pb analyses from these samples yield weighted mean ages of 661 ± 13 ka (YR345: 95% confidence), 655 ± 11 ka (YR311), and 664 ± 15 ka (YR324) (combined weighted mean of 658.8 ± 6.6 ka). We also studied two samples of ignimbrite previously mapped as Huckleberry Ridge Tuff on the northeastern perimeter of the Yellowstone Caldera, 12 km ENE of Sour Creek dome. Sanidines from these samples yield 40Ar/39Ar age estimates of 634.5 ± 6.8 ka (8YC-358) and 630.9 ± 4.1 ka (8YC-359). These age data show that all these units represent previously unrecognized parts of the Lava Creek Tuff and do not have any relationship to the Huckleberry Ridge Tuff. Our observations and data imply that the Lava Creek eruption was more complex than is currently assumed, incorporating two tuff units additional to those currently mapped, and which themselves are separated by a time break sufficient for cooling and some reworking. The presence of a lag breccia suggests that a source vent lay nearby (< 3 km) for some of the tuffs and that the Yellowstone Caldera boundary in this area could be reconsidered.

Seismic variability and structural controls on fluid migration in Northern Oklahoma

NASA Astrophysics Data System (ADS)

Lambert, C.; Keranen, K. M.; Stevens, N. T.

2016-12-01

The broad region of seismicity in northern Oklahoma encompasses distinct structural settings; notably, the area contains both high-length, high-offset faults bounding a major structural uplift (the Nemaha uplift), and also encompasses regions of distributed, low-length, low-offset faults on either side of the uplift. Seismicity differs between these structural settings in mode of migration, rate, magnitude, and mechanism. Here we use our catalog from 2015-2016, acquired using a dense network of 55 temporary broadband seismometers, complemented by data from 40+ regional stations, including the IRIS Wavefields stations. We compare seismicity between these structural settings using precise earthquake locations, focal mechanism solutions, and body-wave tomography. Within and along the dominant Nemaha uplift, earthquakes rarely occur on one of the primary uplift-bounding faults. Earthquakes instead occur within the uplift on isolated, discrete faults, and migrate gradually along these faults at 20-30 m/day. The regions peripheral to the uplift hosted the majority of earthquakes within the year, on multiple series of frequently unmapped, densely-spaced, subparallel faults. We did not detect a similar slow migration along these faults. Earthquakes instead occurred via progressive failure of individual segments along a fault, or jumped abruptly from one fault to another nearby. Mechanisms in both regions are dominantly strike-slip, with the interpreted dominant fault plane orientation rotating from N100E in the Wavefields area (west of the uplift) to N50E (within the uplift). We interpret that the distinct variation in seismicity may result from the variation in fault density and length between the uplift and the surrounding regions. Seismic velocity within the upper basement of the uplift is lower than the velocity on either side, possibly indicative of enhanced fracturing within the uplift, as seen in the Nemaha uplift to the north. The fracturing, along with the large faults, may create fluid pathways that facilitate pressure diffusion. Conversely, outside of the uplift, the numerous small-offset faults that are reactivated appear to be less efficient fluid pathways, inhibiting pressure diffusion and resulting in a higher seismicity rate.

Metabolism of nonparticulate phosphorus in an acid bog lake

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

Koenings, J. P.

1977-01-01

In North Gate Lake, an acid bog lake located on the northern Michigan-Wisconsin border, U.S.A., the algal nutrient inorganic phosphate (FRP) is not detectable by chemical means. Organic phosphorus (FUP) represents 100% of the detectable filterable phosphorus. The availability and cycling of this organic fraction are of considerable interest in regard to the primary productivity of this system. To clarify these relationships, the cycling of nonparticulate forms of phosphorus found in the epilimnion of this lake was studied.

Parameter Calculation Technique for the Waste Treatment Facilities Using Naturally-Aerated Blocks in the Bog Ecosystems

NASA Astrophysics Data System (ADS)

Akhmed-Ogly, K. V.; Savichev, O. G.; Tokarenko, O. G.; Pasechnik, E. Yu; Reshetko, M. V.; Nalivajko, N. G.; Vlasova, M. V.

2014-08-01

Technique for the domestic wastewater treatment in the small residential areas and oil and gas facilities of the natural and man-made systems including a settling tank for mechanical treatment and a biological pond with peat substrate and bog vegetation for biological treatment has been substantiated. Technique for parameters calculation of the similar natural and man-made systems has been developed. It was proven that effective treatment of wastewater can be performed in Siberia all year round.

No limits to peat bog growth? Transport and thermodynamic constraints on anaerobic organic matter decomposition

NASA Astrophysics Data System (ADS)

Blodau, C.; Julia, B.; Siems, M.

2009-05-01

In diffusion dominated systems, for which many thick peat deposits provide a model, slowness of transport and lack of free energy may pose a limit to methanogenic decomposition of organic matter and ultimately to closing the carbon cycle. To test this hypothesis we (I) conducted controlled column experiments with homogenized peat over an 18 month period, (II) investigated transport, in situ respiration pathways, rates and thermodynamic conditions in a nothern peatland, and (III) modelled depth profiles of CO2 and CH4 in the deposits. Vertical transport in the peatland was dominated by diffusion leading to the buildup of DIC and CH4 with depth (5500 µmol L 1 DIC, 500 µmol L 1 CH4). Highest DIC and CH4 production rates occurred close to the water table (decomposition constant kd ~10-3 to 10 4 a-1) and decreased to about kd = 10-7 a-1. The accumulation of metabolic end-products diminished in situ energy yields of acetoclastic methanogenesis to the threshold for microbially mediated processes (-20 to -25 kJ mol-1 CH4). The methanogenic precursor acetate also accumulated (150 µmol L 1). In line with these findings, CH4 was formed by hydrogenotrophic methanogenesis at Gibbs free energies of 35 to 40 kJ mol-1 CH4. This was indicated by an isotopic fractionation αCO2-CH4 of 1.069 to 1.079. Fermentative degradation of acetate, propionate and butyrate attained Gibbs free energies close to 0 kJ mol-1 substrate. In peat columns with homogenenous peat-sand mixtures of 50%, 15% and 5% dry weight, steady state CO2 production also decreased from about 10 to 0 nmol cm-3 d-1 and of CH4 from 1 to 0 nmol cm-3 d-1 with depth. Very similar depth profiles of concentrations and volumetric rates developed near endproduct thresholds of 600µmol CH4 and 10 mmol L-1 CO2, despite the differences in organic matter content. The modeling exercise showed that a consistent development of CH4 concentration profiles over time in the columns could only be accomplished with rates of acetoclastic methanogenesis decreasing to 0 near a critical Gibbs free energy of about -27 KJ mol-1. The results thus suggest that, even in absence of inorganic electron acceptors, respiration rates in peat bogs are likely higher near the redox interface to the atmosphere due to lower respiration endproduct concentrations. Similar effects ensue when rates of transport are elevated or pools of CO2 and CH4 are eliminated. With decomposition being constrained, peat bog growth may occur longer than previously thought.

Comparison between reverse Brayton and Kapitza based LNG boil-off gas reliquefaction system using exergy analysis

NASA Astrophysics Data System (ADS)

Kochunni, Sarun Kumar; Chowdhury, Kanchan

2017-02-01

LNG boil-off gas (BOG) reliquefaction systems in LNG carrier ships uses refrigeration devices which are based on reverse Brayton, Claude, Kapitza (modified Claude) or Cascade cycles. Some of these refrigeration devices use nitrogen as the refrigerants and hence nitrogen storage vessels or nitrogen generators needs to be installed in LNG carrier ships which consume space and add weight to the carrier. In the present work, a new configuration based on Kapitza liquefaction cycle which uses BOG itself as working fluid is proposed and has been compared with Reverse Brayton Cycle (RBC) on sizes of heat exchangers and compressor operating parameters. Exergy analysis is done after simulating at steady state with Aspen Hysys 8.6® and the comparison between RBC and Kapitza may help designers to choose reliquefaction system with appropriate process parameters and sizes of equipment. With comparable exergetic efficiency as that of an RBC, a Kaptiza system needs only BOG compressor without any need of nitrogen gas.

Cranberry flowering times and climate change in southern Massachusetts

NASA Astrophysics Data System (ADS)

Ellwood, Elizabeth R.; Playfair, Susan R.; Polgar, Caroline A.; Primack, Richard B.

2014-09-01

Plants in wild and agricultural settings are being affected by the warmer temperatures associated with climate change. Here we examine the degree to which the iconic New England cranberry, Vaccinium macrocarpon, is exhibiting signs of altered flowering phenology. Using contemporary records from commercial cranberry bogs in southeastern Massachusetts in the United States, we found that cranberry plants are responsive to temperature. Flowering is approximately 2 days earlier for each 1 °C increase in May temperature. We also investigated the relationship between cranberry flowering and flight dates of the bog copper, Lycaena epixanthe—a butterfly dependent upon cranberry plants in its larval stage. Cranberry flowering and bog copper emergence were found to be changing disproportionately over time, suggesting a potential ecological mismatch. The pattern of advanced cranberry flowering over time coupled with increased temperature has implications not only for the relationship between cranberry plants and their insect associates but also for agricultural crops in general and for the commercial cranberry industry.

Cranberry flowering times and climate change in southern Massachusetts.

PubMed

Ellwood, Elizabeth R; Playfair, Susan R; Polgar, Caroline A; Primack, Richard B

2014-09-01

Plants in wild and agricultural settings are being affected by the warmer temperatures associated with climate change. Here we examine the degree to which the iconic New England cranberry, Vaccinium macrocarpon, is exhibiting signs of altered flowering phenology. Using contemporary records from commercial cranberry bogs in southeastern Massachusetts in the United States, we found that cranberry plants are responsive to temperature. Flowering is approximately 2 days earlier for each 1 °C increase in May temperature. We also investigated the relationship between cranberry flowering and flight dates of the bog copper, Lycaena epixanthe-a butterfly dependent upon cranberry plants in its larval stage. Cranberry flowering and bog copper emergence were found to be changing disproportionately over time, suggesting a potential ecological mismatch. The pattern of advanced cranberry flowering over time coupled with increased temperature has implications not only for the relationship between cranberry plants and their insect associates but also for agricultural crops in general and for the commercial cranberry industry.

SPRUCE Tree Growth Assessments of Picea and Larix in S1-Bog Plots and SPRUCE Experimental Plots beginning in 2011

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

Hanson, P.J.,; Phillips, J.R.; Wullschelger, S.D.

This data set reports tree growth measurements of mature Picea mariana and Larix laricina located in the S1-Bog permanent plots and the SPRUCE experimental study plots, Annual data collections were initiated in February of 2011and have been continued on an annual basis during mid-winter observation periods at the end of February or early March. Data collections are anticipated to continue through February of 2025 and this data set will be appended annually. Initial observations in 2011 included measurements of circumference at 1.3 m (diameter at breast height assessments; DBH) above the nominal bog hollow surface, tree heights and crown diameters.more » Subsequent annual measurements have focused on the measures of circumference at DBH. Circumference measurements to the nearest 0.1 cm are converted to DBH in cm and basal area at DBH in (cm2). Tree height and crown diameter are measured to the nearest 0.1 m.« less

A modelling tool for capacity planning in acute and community stroke services.

PubMed

Monks, Thomas; Worthington, David; Allen, Michael; Pitt, Martin; Stein, Ken; James, Martin A

2016-09-29

Mathematical capacity planning methods that can take account of variations in patient complexity, admission rates and delayed discharges have long been available, but their implementation in complex pathways such as stroke care remains limited. Instead simple average based estimates are commonplace. These methods often substantially underestimate capacity requirements. We analyse the capacity requirements for acute and community stroke services in a pathway with over 630 admissions per year. We sought to identify current capacity bottlenecks affecting patient flow, future capacity requirements in the presence of increased admissions, the impact of co-location and pooling of the acute and rehabilitation units and the impact of patient subgroups on capacity requirements. We contrast these results to the often used method of planning by average occupancy, often with arbitrary uplifts to cater for variability. We developed a discrete-event simulation model using aggregate parameter values derived from routine administrative data on over 2000 anonymised admission and discharge timestamps. The model mimicked the flow of stroke, high risk TIA and complex neurological patients from admission to an acute ward through to community rehab and early supported discharge, and predicted the probability of admission delays. An increase from 10 to 14 acute beds reduces the number of patients experiencing a delay to the acute stroke unit from 1 in every 7 to 1 in 50. Co-location of the acute and rehabilitation units and pooling eight beds out of a total bed stock of 26 reduce the number of delayed acute admissions to 1 in every 29 and the number of delayed rehabilitation admissions to 1 in every 20. Planning by average occupancy would resulted in delays for one in every five patients in the acute stroke unit. Planning by average occupancy fails to provide appropriate reserve capacity to manage the variations seen in stroke pathways to desired service levels. An appropriate uplift from the average cannot be based simply on occupancy figures. Our method draws on long available, intuitive, but underused mathematical techniques for capacity planning. Implementation via simulation at our study hospital provided valuable decision support for planners to assess future bed numbers and organisation of the acute and rehabilitation services.

Nutrient additions in pristine Patagonian Sphagnum bog vegetation: can phosphorus addition alleviate (the effects of) increased nitrogen loads.

PubMed

Fritz, C; van Dijk, G; Smolders, A J P; Pancotto, V A; Elzenga, T J T M; Roelofs, J G M; Grootjans, A P

2012-05-01

Sphagnum-bog ecosystems have a limited capability to retain carbon and nutrients when subjected to increased nitrogen (N) deposition. Although it has been proposed that phosphorus (P) can dilute negative effects of nitrogen by increasing biomass production of Sphagnum mosses, it is still unclear whether P-addition can alleviate physiological N-stress in Sphagnum plants. A 3-year fertilisation experiment was conducted in lawns of a pristine Sphagnum magellanicum bog in Patagonia, where competing vascular plants were practically absent. Background wet deposition of nitrogen was low (≈ 0.1-0.2 g · N · m(-2) · year(-1)). Nitrogen (4 g · N · m(-2) · year(-1)) and phosphorus (1 g · P · m(-2) · year(-1)) were applied, separately and in combination, six times during the growing season. P-addition substantially increased biomass production of Sphagnum. Nitrogen and phosphorus changed the morphology of Sphagnum mosses by enhancing height increment, but lowering moss stem density. In contrast to expectations, phosphorus failed to alleviate physiological stress imposed by excess nitrogen (e.g. amino acid accumulation, N-saturation and decline in photosynthetic rates). We conclude that despite improving growth conditions by P-addition, Sphagnum-bog ecosystems remain highly susceptible to nitrogen additions. Increased susceptibility to desiccation by nutrients may even worsen the negative effects of excess nitrogen especially in windy climates like in Patagonia. © 2011 German Botanical Society and The Royal Botanical Society of the Netherlands.

Continuous uplift near the seaward edge of the Prince William Sound megathrust: Middleton Island, Alaska

USGS Publications Warehouse

Savage, James C.; Plafker, George; Svarc, Jerry L.; Lisowski, Michael

2014-01-01

Middleton Island, located at the seaward edge of the continental shelf 50 km from the base of the inner wall of the Aleutian Trench, affords an opportunity to make land-based measurements of uplift near the toe of the Prince William Sound megathrust, site of the 1964, M = 9.2, Alaska earthquake. Leveling surveys (1973–1993) on Middleton Island indicate roughly uniform tilting (~1 µrad/a down to the northwest) of the island, and GPS surveys (1993–2012) show an uplift rate of 14 mm/a of the island relative to fixed North America. The data are consistent with a combined (coseismic and postseismic) uplift (in meters) due to the 1964 earthquake as a function of time τ (years after the earthquake) u(τ) = (3.5 + 1.21 log10 [1 + 1.67 τ]) H(τ) where 3.5 is the coseismic uplift and H(τ) is 0 for τ < 0 and 1 otherwise. The current uplift on Middleton Island is attributed to continuous slip on a fault splaying off from the megathrust, and the long-term uplift is the superposition of the effects of past earthquakes, each earthquake being similar to the 1964 event. Then, the predicted uplift at time t due to a sequence of earthquakes at times tiwould be . From studies of strandlines associated with the uplifted terraces on Middleton Island, Plafker et al. (1992) estimated the occurrence times of the last six earthquakes and measured the present-day elevations of those strandlines. The predicted uplift is in rough agreement with those measurements. About half of the predicted uplift is due to postseismic relaxation from previous earthquakes.

Continuous uplift near the seaward edge of the Prince William Sound megathrust: Middleton Island, Alaska

NASA Astrophysics Data System (ADS)

Savage, J. C.; Plafker, G.; Svarc, J. L.; Lisowski, M.

2014-07-01

Middleton Island, located at the seaward edge of the continental shelf 50 km from the base of the inner wall of the Aleutian Trench, affords an opportunity to make land-based measurements of uplift near the toe of the Prince William Sound megathrust, site of the 1964, M = 9.2, Alaska earthquake. Leveling surveys (1973-1993) on Middleton Island indicate roughly uniform tilting ( 1 µrad/a down to the northwest) of the island, and GPS surveys (1993-2012) show an uplift rate of 14 mm/a of the island relative to fixed North America. The data are consistent with a combined (coseismic and postseismic) uplift (in meters) due to the 1964 earthquake as a function of time τ (years after the earthquake) u(τ) = (3.5 + 1.21 log10 [1 + 1.67 τ]) H(τ) where 3.5 is the coseismic uplift and H(τ) is 0 for τ < 0 and 1 otherwise. The current uplift on Middleton Island is attributed to continuous slip on a fault splaying off from the megathrust, and the long-term uplift is the superposition of the effects of past earthquakes, each earthquake being similar to the 1964 event. Then, the predicted uplift at time t due to a sequence of earthquakes at times ti would be ∑iut-ti. From studies of strandlines associated with the uplifted terraces on Middleton Island, Plafker et al. (1992) estimated the occurrence times of the last six earthquakes and measured the present-day elevations of those strandlines. The predicted uplift is in rough agreement with those measurements. About half of the predicted uplift is due to postseismic relaxation from previous earthquakes.

Quantitative dating of Pleistocene terrace deposits of the Kyrenia Range, northern Cyprus: implications for timing, rates of uplift and driving mechanisms in an incipient collision zone

NASA Astrophysics Data System (ADS)

Palamakumbura, Romesh; Robertson, Alastair; Kinnaird, Tim; van Calsteren, Peter; Kroon, Dick; Tait, Jenny

2016-04-01

The Kyrenia Range is a narrow E-W trending mountain range up to c. 180 km long by up to ca. 20 km wide, which is located <100 km south of the Anatolian orogenic plateau within the easternmost Mediterranean Sea. The Kyrenia Range structural lineament underwent tectonically driven uplift mainly during the Pleistocene in a setting dominated by incipient continental collision. The likely driver of the uplift was the collision of the Eratosthenes Seamount, an inferred promontory of north Africa, with a subduction zone located to the south of Cyprus. To help understand the tectonic processes driving the uplift of the Kyrenia Range several quantitative techniques have been used to date uplift-related terrace deposits exposed on the northern flank of the range. Uranium-series disequilibrium (U-series) dating provides ages of 127, 131 and 242 ka from solitary coral in shallow-marine deposits of the lowest terraces, whereas optically stimulated luminescence (OSL) dating gives ages of 53 and 76 ka from coastal aeolianite deposits. Prior to major tectonic uplift a shallow-marine carbonate-depositing sea existed in the vicinity of the Kyrenia Range. Some of the youngest pre-uplift marine carbonates yielded a reversed magnetic polarity, which constrains them as older than the last palaeomagnetic reversal (0.78 Ma). The combined evidence suggests that marine environments persisted into the Early Pleistocene, prior to major surface uplift of the Kyrenia Range lineament, which appears to have climaxed in the Mid-Pleistocene. The inferred uplift rates of the Kyrenia Range lineament range from >1.2 mm/yr during the Mid-Pleistocene to <0.2 mm/yr during the Late Pleistocene. The uplift rates of the Kyrenia Range appear to be, on average, significantly faster than those inferred for some adjacent regions of the Eastern Mediterranean during the Pleistocene (e.g. Lebanon coast; Anatolian plateau southern margin). The new data also suggest that the Kyrenia Range was uplifted contemporaneously with the ophiolitic Troodos Massif in southern Cyprus, which is in keeping with the model of regional-scale collision of the Eratosthenes Seamount with the Cyprus trench. The uplift of the Kyrenia Range lineament took place directly adjacent to the southern margin of the much larger Anatolian orogenic plateau, which was also mainly uplifted during the Pleistocene. The timing and processes involved in the uplift of the Kyrenia Range lineament are relevant to long-term processes of continental accretion and plateau uplift. On a longer timescale, the uplift of the Kyrenia Range in an incipient collisional setting can be seen as a step towards final accretion into a larger Anatolian orogenic plateau as collision intensifies. Terranes similar to the Kyrenia Range lineament may therefore exist embedded within the uplifted margins of orogenic plateaus in other areas of the world (e.g. southern Tibet).

Quaternary uplift and tilting of Amorgos Island (southern Aegean) and the 1956 earthquake

NASA Astrophysics Data System (ADS)

Stiros, Stathis C.; Marangou, Lila; Arnold, Maurice

1994-12-01

Uplifted Pleistocene marine sediments, submerged ancient ruins and raised beaches confirm earlier views that the asymmetry of the relief of Amorgos Island (southern Aegean) testifies to a fault-bounded block uplifted and tilted along a SW-NE trending horizontal axis; the uplifted coast corresponds to a high-gradient slope controlled by an oblique master normal fault. Furthermore, geomorphic and biological evidence, radiometric data and comparison of aerial photographs indicates that the 1956 earthquake (Ms = 7.4) uplifted the footwall of this normal fault by about 30 cm.

SPRUCE Epiphytic Lichen Annual Biomass Growth in Experimental Plots, 2013-2016.

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

Smith, R.J.; Nelson, P.R.; Jovan, S.

This data set provides annual biomass growth rates of epiphytic lichen transplants in the SPRUCE experimental plots at the S1 Bog of the Marcell Experimental Forest. Epiphytic lichens (Evernia mesomorpha, a boreal forest indicator species) were collected at S1 Bog outside the experimental enclosures and mounted on Picea mariana branches inside the 10 experimental enclosures and the 2 ambient plots without enclosures using transplant techniques. Lichen transplants were weighed annually, in August of 2013-2016, to measure biomass growth rates as a function of experimental temperature and CO2 treatments.

[Testate amoebae inhabiting middle taiga bogs in Western Siberia].

PubMed

Kur'ina, I V; Preĭs, Iu I; Bobrov, A A

2010-01-01

The population of testate amoebae from the most typical middle taiga bogs of Western Siberia have been studied. More than one hundred (103) species and intraspecific taxons of testate amoebae have been revealed in recent surface samples. The relation between ecological characteristics of habitats and the composition of a Protozoa population has been demonstrated. The ecological preferences of species concerning the index of wetness, ash level, and acidity have been revealed. Using the correspondence analysis, the ecological optimums and the tolerance of species and intraspecific taxons of testate amoebae have been established.

SPRUCE Bog Surface Elevation Assessments with SET Instrument Beginning in 2013

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

Hanson, Paul J; Phillips, Jana R; Brice, Deanne J

This data set reports plot-specific bog surface elevation measurements collected with the SPRUCE Elevation Transect (SET) instrument. Measurements are reported as absolute elevation in meters above mean sea level for two locations in each of the SPRUCE experimental treatment plots and additional ambient boardwalk plots -- 4, 5, 6, 7, 8, 9, 10, 11, 13, 14, 15, 16, 17, 19, 20 and 21. This data set reports measurements collected from June 2013 through August 2017, but it will be appended annually as new data are collected.

Soil data for a collapse-scar bog chronosequence in Koyukuk Flats National Wildlife Refuge, Alaska, 2008

USGS Publications Warehouse

O’Donnell, Jonathan A.; Harden, Jennifer W.; Manies, Kristen L.; Jorgenson, M. Torre

2012-01-01

Peatlands in the northern permafrost region store large amounts of organic carbon, most of which is currently stored in frozen peat deposits. Recent warming at high-latitudes has accelerated permafrost thaw in peatlands, which will likely result in the loss of soil organic carbon from previously frozen peat deposits to the atmosphere. Here, we report soil organic carbon inventories, soil physical data, and field descriptions from a collapse-scar bog chronosequence located in a peatland ecosystem at Koyukuk Flats National Wildlife Refuge in Alaska.

Daily hassles and uplifts: a diary study on understanding relationship quality.

PubMed

Totenhagen, Casey J; Serido, Joyce; Curran, Melissa A; Butler, Emily A

2012-10-01

In this investigation, we use the Conservation of Resources (CoR) theory as a guide to examine how both uplifts and hassles are associated with positive (e.g., satisfaction, commitment) and negative (ambivalence, conflict) relational quality on a daily basis. In previous studies of hassles and uplifts, the focus has been primarily on negative outcomes at the individual level (e.g., affect). Here, we build on this previous research in examining both positive and negative events (i.e., uplifts and hassles) in associations with positive and negative relational qualities. Further, we focus on examining social and nonsocial events that are external to the relationship (i.e., do not involve the romantic partner) and how they are linked with relational qualities. Finally, we examine which patterns are confined to the same day and which carry over to subsequent days (i.e., lagged effects). Contrary to previous literature, we find that both social and nonsocial hassles are largely unrelated to relationship quality after accounting for the effects of social and nonsocial uplifts. In contrast, nonsocial uplifts bolster positive feelings about the relationship on that day. Results also show that hassles and uplifts may work together to explain relational commitment. Finally, we find that nonsocial uplifts experienced on one day are associated with trend-level declines in next day positive feelings about the relationship. Our findings suggest that preserving relationship quality through daily experiences is best achieved by equipping couples to recognize the benefits of uplifts to the relationship, especially uplifts that are nonsocial, in tandem with managing hassles. (PsycINFO Database Record (c) 2012 APA, all rights reserved).

Episodic swell growth inferred from variable uplift of the Cape Verde hotspot islands

USGS Publications Warehouse

Ramalho, R.; Helffrich, G.; Cosca, M.; Vance, D.; Hoffmann, D.; Schmidt, D.N.

2010-01-01

On the Beagle voyage, Charles Darwin first noted the creation and subsidence of ocean islands, establishing in geology's infancy that island freeboard changes with time. Hotspot ocean islands have an obvious mechanism for freeboard change through the growth of the bathymetric anomaly, or swell, on which the islands rest. Models for swell development indicate that flexural, thermal or dynamic pressure contributions, as well as spreading of melt residue from the hotspot, can all contribute to island uplift. Here we test various models for swell development using the uplift histories for the islands of the Cape Verde hotspot, derived from isotopic dating of marine terraces and subaerial to submarine lava-flow morphologies. The island uplift histories, in conjunction with inter-island spacing, uplift rate and timing differences, rule out flexural, thermal or dynamic pressure contributions. We also find that uplift cannot be reconciled with models that advocate the spreading of melt residue in swell development unless swell growth is episodic. Instead, we infer from the uplift histories that two processes have acted to raise the islands during the past 6 Myr. During an initial phase, mantle processes acted to build the swell. Subsequently, magmatic intrusions at the island edifice caused 350 m of local uplift at the scale of individual islands. Finally, swell-wide uplift contributed a further 100 m of surface rise.

Episodic swell growth inferred from variable uplift of the Cape Verde hotspot islands

NASA Astrophysics Data System (ADS)

Ramalho, R.; Helffrich, G.; Cosca, M.; Vance, D.; Hoffmann, D.; Schmidt, D. N.

2010-11-01

On the Beagle voyage, Charles Darwin first noted the creation and subsidence of ocean islands, establishing in geology's infancy that island freeboard changes with time. Hotspot ocean islands have an obvious mechanism for freeboard change through the growth of the bathymetric anomaly, or swell, on which the islands rest. Models for swell development indicate that flexural, thermal or dynamic pressure contributions, as well as spreading of melt residue from the hotspot, can all contribute to island uplift. Here we test various models for swell development using the uplift histories for the islands of the Cape Verde hotspot, derived from isotopic dating of marine terraces and subaerial to submarine lava-flow morphologies. The island uplift histories, in conjunction with inter-island spacing, uplift rate and timing differences, rule out flexural, thermal or dynamic pressure contributions. We also find that uplift cannot be reconciled with models that advocate the spreading of melt residue in swell development unless swell growth is episodic. Instead, we infer from the uplift histories that two processes have acted to raise the islands during the past 6Myr. During an initial phase, mantle processes acted to build the swell. Subsequently, magmatic intrusions at the island edifice caused 350m of local uplift at the scale of individual islands. Finally, swell-wide uplift contributed a further 100m of surface rise.

Do Hassles and Uplifts Change with Age? Longitudinal Findings from the VA Normative Aging Study

PubMed Central

Aldwin, Carolyn M.; Jeong, Yu-Jin; Igarashi, Heidi; Spiro, Avron

2014-01-01

To examine emotion regulation in later life, we contrasted the modified hedonic treadmill theory with developmental theories, using hassles and uplifts to assess emotion regulation in context. The sample was 1,315 men from the VA Normative Aging Study aged 53 to 85 years, who completed 3,894 observations between 1989 and 2004. We computed three scores for both hassles and uplifts: intensity (ratings reflecting appraisal processes), exposure (count), and summary (total) scores. Growth curves over age showed marked differences in trajectory patterns for intensity and exposure scores. Although exposure to hassles and uplifts decreased in later life, intensity scores increased. Growth based modelling showed individual differences in patterns of hassles and uplifts intensity and exposure, with relative stability in uplifts intensity, normative non-linear changes in hassles intensity, and complex patterns of individual differences in exposure for both hassles and uplifts. Analyses with the summary scores showed that emotion regulation in later life is a function of both developmental change and contextual exposure, with different patterns emerging for hassles and uplifts. Thus, support was found for both hedonic treadmill and developmental change theories, reflecting different aspects of emotion regulation in late life. PMID:24660796

Do hassles and uplifts change with age? Longitudinal findings from the VA normative aging study.

PubMed

Aldwin, Carolyn M; Jeong, Yu-Jin; Igarashi, Heidi; Spiro, Avron

2014-03-01

To examine emotion regulation in later life, we contrasted the modified hedonic treadmill theory with developmental theories, using hassles and uplifts to assess emotion regulation in context. The sample was 1,315 men from the VA Normative Aging Study aged 53 to 85 years, who completed 3,894 observations between 1989 and 2004. We computed 3 scores for both hassles and uplifts: intensity (ratings reflecting appraisal processes), exposure (count), and summary (total) scores. Growth curves over age showed marked differences in trajectory patterns for intensity and exposure scores. Although exposure to hassles and uplifts decreased in later life, intensity scores increased. Group-based modeling showed individual differences in patterns of hassles and uplifts intensity and exposure, with relative stability in uplifts intensity, normative nonlinear changes in hassles intensity, and complex patterns of individual differences in exposure for both hassles and uplifts. Analyses with the summary scores showed that emotion regulation in later life is a function of both developmental change and contextual exposure, with different patterns emerging for hassles and uplifts. Thus, support was found for both hedonic treadmill and developmental change theories, reflecting different aspects of emotion regulation in late life. (c) 2014 APA, all rights reserved.

Evolution of stickleback in 50 years on earthquake-uplifted islands

PubMed Central

Lescak, Emily A.; Bassham, Susan L.; Catchen, Julian; Gelmond, Ofer; Sherbick, Mary L.; von Hippel, Frank A.

2015-01-01

How rapidly can animal populations in the wild evolve when faced with sudden environmental shifts? Uplift during the 1964 Great Alaska Earthquake abruptly created freshwater ponds on multiple islands in Prince William Sound and the Gulf of Alaska. In the short time since the earthquake, the phenotypes of resident freshwater threespine stickleback fish on at least three of these islands have changed dramatically from their oceanic ancestors. To test the hypothesis that these freshwater populations were derived from oceanic ancestors only 50 y ago, we generated over 130,000 single-nucleotide polymorphism genotypes from more than 1,000 individuals using restriction site-associated DNA sequencing (RAD-seq). Population genomic analyses of these data support the hypothesis of recent and repeated, independent colonization of freshwater habitats by oceanic ancestors. We find evidence of recurrent gene flow between oceanic and freshwater ecotypes where they co-occur. Our data implicate natural selection in phenotypic diversification and support the hypothesis that the metapopulation organization of this species helps maintain a large pool of genetic variation that can be redeployed rapidly when oceanic stickleback colonize freshwater environments. We find that the freshwater populations, despite population genetic analyses clearly supporting their young age, have diverged phenotypically from oceanic ancestors to nearly the same extent as populations that were likely founded thousands of years ago. Our results support the intriguing hypothesis that most stickleback evolution in fresh water occurs within the first few decades after invasion of a novel environment. PMID:26668399

landforms evolution in collisional-dominated settings: the case of Northern Sicily (Central Mediterranean)

NASA Astrophysics Data System (ADS)

Nigro, Fabrizio; Renda, Pietro; Favara, Rocco

2010-05-01

In the young mountain chains underwent to emersion, the different crustal blocks which compose the belt may be subjected to differentiate tilting during uplift. The tilting process may be revealed both by the stratal pattern of the syn-uplifting deposits or deduced by the function altitude/area ratio. The prevailing of the uplift rate with respect to the tilting rate (and vice versa) result from the shape of this function. So, in young mountains the hypsometric analysis may results a useful tool for decipher how the crustal blocks are underwent to uplift. An integrate analysis based on stratigraphy, structural and morphometric data represents the correctly approach for characterise the landform evolution in regions underwent to active tectonics. In the aim to evaluate the recent tectonic history from topography in regions underwent to active deformations, by deducing the effect of tectonisms on landforms, the definition of the boundary conditions (regarding the crustal deformation) is fundamental for morphometric analysis. In fact, the morphologic style and the morphometric pattern in tectonically active settings are closely related to the dominance of rock masses exceeding for uplift (or failure for subsidence) with respect to the exogenous erosional processes. Collisional geodynamic processes induce crustal growth for faulting and folding. In this earth's sectors, the uplift of crustal blocks is a very common effect of compressional deformation. It reflects for example fold amplification and thrusting, but it is a very common process also in settings dominated by crustal thinning, where the viscoelastic properties of the lithosphere induce tilting and localised uplift of normal-faulted crustal blocks. The uplift rate is rarely uniform for wide areas within the orogens on the passive margins, but it changes from adjacent crustal blocks as the effect of space-variation of kinematics conditions or density. It also may change within a single block, as the effect of tilting, which induces synchronously mass elevation and subsidence. Not considering sea-level fluctuations and the climatic-lithologic parameters, the 2D distribution of uplift rate influences the landmass evolution in time. The tendency of rock masses to equilibrium resulting from concurrent tectonic building and denudation forces defines the geomorphic cycle. This evolution is checked by different stages, each characterised by a well-recognisable morphometric patterns. The dominance of uplift or erosion and concurrent block tilting induce characteristic a landform evolution tendency, which may be evaluated with the morphometric analysis. A lot of morphometric functions describe the equilibrium stage of landmasses, providing useful tools for deciphering how tectonics acts in typology (e.g. inducing uplift uniformly or with crustal block tilting) and resulting effects on landforms (magnitude of uplift rate vs tilting rate). We aim to contribute in the description of landforms evolution in Sicily (Central Mediterranean) under different morphoevolutive settings, where may prevails uplift, tilting or erosion, each characterised by different morphometric trends. The present-day elevation of Pliocene to upper Pleistocene deposits suggests that Northen Sicily underwent neotectonic uplift. The recent non-uniform uplift of Northern Sicily coastal sector is suggested by the different elevation of the Pliocene-Upper Pleistocene marine deposits. The maximum uplift rate characterise the NE Sicily and the minimum the NW Sicily. The overall westwards decreasing trend of uplift is in places broken in the sectors where are located a lot of morphostructures. Localised uplift rates higher than the adjacent coastal plains are suggested by the present-day elevation of the beachshore deposits of Tyrrhenian age. Northern Sicily may be divided into a lot of crustal blocks, underwent to different tilting and uplift rates. Accentuate tilting and uplift results from transtensional active faulting of the already emplaced chain units, as also suggested by seismicity and the focal plane solutions of recent strong earthquakes.

The evolution of the southern California uplift, 1955 through 1976

USGS Publications Warehouse

Castle, Robert O.; Elliot, Michael R.; Church, Jack P.; Wood, Spencer H.

1984-01-01

The southern California uplift culminated in 1974 as a 150- km-wide crustal swell that extended about 600 km eastward and east-southeastward from Point Arguello to the Colorado River and Salton Sea, respectively; it was characterized by remarkably uniform height changes between 1959 and 1974 of 0.30-0.35 m over at least half of its 60,000-70,000 km2 area. At its zenith, the uplift included virtually the entire Transverse Ranges geologic province and parts of the Coast Ranges, San Joaquin Valley, Sierra Nevada, Basin and Range, Mojave Desert, Peninsular Ranges, and Salton Trough provinces. The alinement of the western part of the uplift closely paralleled the east-trending Transverse Ranges, whereas the southern flank of the eastern lobe roughly coincided with the west-northwest-trending San Andreas fault. The position and configuration of the uplift associate it with a singularly complex section of the boundary between the North American and Pacific plates that has certainly sustained major modification during the past 5 million years and probably during the past 1 million years. Surface deformation can be categorized as tectonic or nontectonic. Nontectonic vertical displacements associated with the activities of man have overwhelmed natural compaction and areally significant soil expansion in the southern California area. Because tectonic displacements are implicitly defined as those that cannot be otherwise explained, those vertical movements that can be reasonably attributed to artificial processes have been subtracted from our reconstructed configurations of the uplift. Hence this reconstruction has necessarily included the assembly and evaluation of an enormous volume of data on oil-field operations, changes in ground-water levels, and measured subsidence (or rebound) associated with changes in the underground fluid regimen. Measured changes in height at various stages in the evolution of the uplift have been based chiefly on first-order levelings carried out between 1953 and 1976. Exceptions to this generalization consist largely of the results of pre-1953 surveys through the western Transverse Ranges and the eastern Mojave Desert. Errors in measured height differences derive from blunders, systematic survey errors, random survey errors, improperly formulated orthometric corrections, and intrasurvey movement; the last of these has created the most serious problems encountered in our reconstruction of the basic data. A variety of independent tests indicate that survey error associated with the utilized levelings was generally small and fell largely within the predicted random-error range. Moreover, the redundancy and coherence displayed by the entire data set provide convincing evidence of survey accuracy and the virtual absence of height- and slope-dependent error in particular. Our reconstructions of the changing configuration of the uplift derive chiefly from comparisons among sequentially developed observed elevations along the same route. Most of the observed elevations from which the vertical displacements were computed have been reconstructed with respect to bench mark Tidal 8, San Pedro, as invariant in height. Because the San Pedro tide station has been characterized by a history of modest relative uplift, vertical displacements referred to this station are biased slightly toward the appearance of subsidence. Where the observed elevations cannot be conveniently tied to Tidal 8, they have been referred to secondary control points whose history with respect to Tidal 8 can be independently established. Each of the lines of observed elevation changes provides, accordingly, a section athwart or along the axis of the uplift from which the changes in the configuration of the uplift can be roughly generalized. Because relatively few surveys were run in 1955, which we choose as a representative temporal datum, we have commonly incorporated the results of earlier or of somewhat later levelings as the equivalents of 1955 surveys. Although this procedure introduces a certain subjectivity, the probable equivalence between the results of these earlier or later surveys with those that would have been obtained had this leveling been carried out in 1955, usually can be independently tested. Wherever the calculated vertical displacements are based on comparisons between the results of levelings over different routes, the observed elevations have been orthometrically corrected to agree with those that would have been produced had each of these surveys been along the same route. The growth of the southern California uplift consisted of two well-defined spasms of positive movement, the second of which was closely followed by partial collapse. Our reconstruction, although it clearly errs in detail, indicates that the uplift, together with marginal and apparently ephemeral tectonic subsidence, nucleated in the west-central Transverse Ranges near Ozena, sometime between the spring of 1959 and the spring of 1960. The uplift expanded rapidly eastward (and probably westward as well), and by the fall of 1961 much of the Transverse Ranges and the Mojave Desert at least as far east as Twentynine Palms had risen by as much as 0.25 m. Between 1962 and 1972 the area included by the initially developed (1959-61) uplift sustained additional but clearly decelerating uplift accompanied locally by oscillatory displacements. Between 1972/ 73 and 1974 a second crustal spasm extended the uplift eastward to the Colorado River and elevated much of the eastern Mojave Desert by values that equaled or exceeded those developed within the western lobe. Between 1974 and 1976, at least the central part of the uplift sustained partial collapse that nowhere amounted to less than 50 percent of the cumulative uplift since 1959. Whether this collapse affected the entire uplift is conjectural, but we now recognize well-defined evidence of major down-to-the-north tilting that must have occurred within the eastern part of the uplift at some time between 1974 and 1976. Accumulating evidence indicates that nearly all the area included with the southern California uplift underwent similar uplift and partial collapse during the early part of the 20th century. Thus we infer that the recent uplift represents but a single event in an ongoing, more or less cyclic deformational process characterized by a period of about 50 years. Even though less than two full cycles are expressed in the geodetic record, the cumulative rate of uplift near the center of the recent uplift probably has averaged about 5 mm/yr, a value that is roughly consistent with the uplift rates that have been deduced for the late Quaternary emergent marine terraces along the south flank of the Transverse Ranges. Although the evolution of the recent uplift is relatively well defined, its correlation with the regional seismicity is poorly defined. A comparison between the occurrence of southern California earthquakes of magnitude ≥4 during the period 1932 to 1976 with the 1974 configuration of the uplift demonstrates the existence of (1) relatively aseismic areas within the western lobe of the uplift (in the western Transverse Ranges), in the central part of the uplift (in the western Mojave Desert), and along an east-trending zone that extends into the eastern Mojave athwart the south flank of the uplift (north of the Salton Sea) and (2) localized concentrations of seismic activity along the flanks of the uplift. Moreover, 9 of the 10 largest earthquakes recorded within or around the area of the southern California uplift during the period 1932 to 1976 (the 1933 Long Beach, the 1941 Santa Barbara, the 1946 Walker Pass, the 1947 Manix, the 1948 Desert Hot Springs, and the four major 1952 Kern County shocks) occurred before the inception of the uplift in 1959 or 1960. The area embraced by the southern California uplift has been identified with geodetically defined horizontal strain, part of which may have accumulated as a major north-south contractional event that roughly coincided with the first spasm of uplift. Nonetheless, continuing contractional strain associated with regionally developed partial collapse argues that the uplift cannot be fully explained simply as the vertical expression of continuing north-south compression. Consideration of the two well-defined historical episodes of uplift and partial collapse indicate that the southern California uplift may be the product of decoupling and viscous flow beneath the seismogenic zone, presumably driven by continuing motion between the irregularly margined plates south of the great bend of the San Andreas fault. Because the magnitude of the maximum uplift associated with each episode was approximately the same, there may be some threshold value above which collapse (viscous flow) may ensue; the absence of total collapse may be a function of precollapse strain hardening within the postulated subseismogenic viscoelastic layer.

Extracting Uplift Rate Histories From Longitudinal River Profiles: Examples From North America and Africa

NASA Astrophysics Data System (ADS)

Roberts, Gareth G.; White, Nicky; Paul, Jonathan

2013-04-01

The physiography of the Earth's surface is a manifestation of vertical motions, erosion, and deposition of sediment. We show that a history of uplift rate of the continents during the last ~ 100 million years can be determined by jointly inverting the longitudinal profiles of rivers. We assume that the shape of a river profile is controlled by the history of uplift rate and moderated by the erosional process. We have parameterized fluvial erosion using a nonlinear advective-diffusive formulation. A river profile per se contains no information about the erosional timescale; values of erosional parameters must be calibrated. If either vertical incision rate or knickzone retreat rate is known independently, for example when palaeo-river profiles are preserved, we can calibrate the erosional model directly. Independent spot measurements of uplift offer another way to calibrate a regional model. In our inverse model, uplift rate is allowed to vary smoothly as a function of space and time, and upstream drainage area is invariant. Using this inverse methodology, we show that there exist time-correlative commonalities in the shapes of river profiles draining uplifted regions. We find that the rate at which knickzones propagate upstream is linearly dependent on slope in nearly all cases (i.e. n = 1 in the detachment-limited erosional model for ~ 600 North American and African rivers). The exponent on upstream drainage, m, which controls knickzone retreat rate, is typically < 0.5. Calculated retreat rates are therefore insensitive to large changes in upstream drainage area. Simultaneous inversion of profiles from the Colorado, Columbia, Mississippi and Rio Grande catchments shows that western North America experienced three regional phases of uplift during the last 100 Ma. The first phase of uplift occurred between 80-50 Ma, which generated ~ 1 km of topography at a rate of ~ 0.03 mm/yr. A second phase of uplift generated ~ 1.5 km of topography between 35-15 Ma at a rate of ~ 0.06 mm/yr. A final and smaller phase of uplift commenced ~ 5 Ma. These distinct phases of uplift are corroborated by spot estimates of palaeoaltimetry, timed growth of relief, thermochronometric data and by stratigraphic evidence of pulsed clastic efflux delivered to the Gulf of Mexico. An episodic uplift history is consistent with punctuated dynamic support of a large region, which is currently centred on Yellowstone. Inversion of the Congo, Nile, Niger, Ogooue, Orange, Zambezi rivers and their major tributaries indicates that domal swells in Africa have experienced a staged uplift history. The West African margin has experienced at least two phases of uplift during the last 30 Ma. Uplift in Afar began ~ 35 Ma. The Hoggar and Tibesti swells, in central North Africa, have an older history of uplift. These results are consistent with a staged magmatic history, delivery of sediment to the continental margins and stratigraphic observations, which suggest that the African landscape is responding to convection in the mantle.

Surface expression of Eastern Mediterranean slab dynamics: Uplift at the SW margin of the Central Anatolian Plateau

NASA Astrophysics Data System (ADS)

Schildgen, T. F.; Cosentino, D.; Caruso, A.; Yildirim, C.; Echtler, H.; Strecker, M. R.

2011-12-01

The Central Anatolian plateau in Turkey borders one of the most complex tectonic regions on Earth, where collision of the Arabian plate with Eurasia in Eastern Anatolia transitions to a cryptic pattern of subduction of the African beneath the Eurasian plate, with concurrent westward extrusion of the Anatolian microplate. Topographic growth of the southern margin of the Central Anatolian plateau has proceeded in discrete stages that can be distinguished based on the outcrop pattern and ages of uplifted marine sediments. These marine units, together with older basement rocks and younger continental sedimentary fills, also record an evolving nature of crustal deformation and uplift patterns that can be used to test the viability of different uplift mechanisms that have contributed to generate the world's third-largest orogenic plateau. Late Miocene marine sediments outcrop along the SW plateau margin at 1.5 km elevation, while they blanket the S and SE margins at up to more than 2 km elevation. Our new biostratigraphic data limit the age of 1.5-km-high marine sediments along the SW plateau margin to < 7.17 Ma, while regional lithostratigraphic correlations imply that the age is < 6.7 Ma. After reconstructing the post-Late Miocene surface uplift pattern from elevations of uplifted marine sediments and geomorphic reference surfaces, it is clear that regional surface uplift reaches maximum values along the modern plateau margin, with the SW margin experiencing less cumulative uplift compared to the S and SE margins. Our structural measurements and inversion modeling of faults within the uplifted region agree with previous findings in surrounding regions, with early contraction followed by strike-slip and extensional deformation. Shallow earthquake focal mechanisms show that the extensional phase has continued to the present. Broad similarities in the onset of surface uplift (after 7 Ma) and a change in the kinematic evolution of the plateau margin (after 8 Ma) suggest that these phenomena may have been linked with a change in the tectonic stress field associated with the process(es) causing post-7 Ma surface uplift. The complex geometry of lithospheric slabs beneath the southern plateau margin, early Pliocene to recent alkaline volcanism, and the localized uplift pattern with accompanying tensional/transtensional stresses point toward slab tearing and localized heating at the base of the lithosphere as a probable mechanism for post-7 Ma uplift of the SW margin. Considering previous work in the region, slab break-off is more likely responsible for non-contractional uplift along the S and SE margins. Overall there appears to be an important link between slab dynamics and surface uplift across the whole southern margin of the Central Anatolian plateau.

Pools and fluxes of organic matter in a boreal landscape: implications for a safety assessment of a repository for nuclear waste.

PubMed

Kumblad, Linda; Söderbäck, Björn; Löfgren, Anders; Lindborg, Tobias; Wijnbladh, Erik; Kautsky, Ulrik

2006-12-01

To provide information necessary for a license application for a deep repository for spent nuclear fuel, the Swedish Nuclear Fuel and Waste Management Co is carrying out site investigations, including extensive studies of different parts of the surface ecosystems, at two sites in Sweden. Here we use the output from detailed modeling of the carbon dynamics in the terrestrial, limnic and marine ecosystems to describe and compare major pools and fluxes of organic matter in the Simpevarp area, situated on the southeast coast of Sweden. In this study, organic carbon is used as a proxy for radionuclides incorporated into organic matter. The results show that the largest incorporation of carbon into living tissue occurs in terrestrial catchments. Carbon is accumulated in soil or sediments in all ecosystems, but the carbon pool reaches the highest values in shallow near-land marine basins. The marine basins, especially the outer basins, are dominated by large horizontal water fluxes that transport carbon and any associated contaminants into the Baltic Sea. The results suggest that the near-land shallow marine basins have to be regarded as focal points for accumulation of radionuclides in the Simpevarp area, as they receive a comparatively large amount of carbon as discharge from terrestrial catchments, having a high NPP and a high detrital accumulation in sediments. These focal points may constitute a potential risk for exposure to humans in a future landscape as, due to post-glacial land uplift, previous accumulation bottoms are likely to be used for future agricultural purposes.

Dynamic topography of the southern Central Anatolian Plateau, Turkey, and geodynamic driving mechanisms

NASA Astrophysics Data System (ADS)

Schildgen, T. F.; Cosentino, D.; Dudas, F. O.; Niedermann, S.; Strecker, M. R.; Echler, H.; Yildirim, C.

2010-12-01

Collision between Eurasia and Arabia and subsequent westward extrusion of the Anatolian microplate explains the development of major intracontinental fault systems in Anatolia that have remained active to the present-day. Concurrent, and probable episodic uplift of the Central and Eastern Anatolian plateaus (CAP and EAP), however, suggests that additional geodynamic mechanisms have contributed to the late Cenozoic morphologic development of the region. Sedimentary basins spanning the southern margin of the CAP provide insights on the timing and rates of different phases of surface uplift, giving constraints to test which geodynamic processes have contributed to surface uplift, orogenic plateau growth, and coupled landscape/climate evolution. Stratigraphic and geomorphic records of uplift and subsidence in the Mut Basin at the southern CAP margin and along the Göksu River record dynamic topographic development. Biostratigraphy and Sr isotope stratigraphy on the highest (ca. 2 km) uplifted marine sediments of the Mut basin furnish a maximum age of ca. 8 Ma for the onset of late Cenozoic uplift of the region. A Pliocene to early Pleistocene marine section, inset within the older stratigraphy at ca. 0.2 to 1.2 km elevation, reveals a history of subsidence and renewed uplift, following the initial uplift that occurred between ca. 8 Ma and Pliocene time. The most recent phase of uplift continued with possibly minor interruptions during the Quaternary, and is recorded by a series of fluvial terraces preserved between 30 and 143 m above the modern Göksu River. One terrace (143 m) reveals a 21Ne model exposure age of ca. 160 ka; ongoing exposure age determination will further constrain the uplift history. Different geodynamic mechanisms have likely contributed to surface uplift along the southern CAP margin. Initial uplift may have been associated with the predominantly sinistral Ecemis fault system that spans the southern and southeastern CAP margin. Neogene counter-clockwise rotation of Central Anatolia and changes in regional fault kinematics, which likely caused local compression along structures with previous sinistral strike-slip kinematics, may have contributed to early deformation and uplift of the region. Our stratigraphic and field data, together with regional geophysical anomalies, suggest that more recent uplift may be related to upwelling asthenosphere through a slab window, which formed when the initial slab detachment associated with the Bitlis-Zagros collision zone (southern margin of the EAP) propagated to the southwest. The intervening Pliocene to early Pleistocene subsidence was likely related to E-W stretching of the southern margin, possibly driven by oroclinal bending of the margin.

A New Appraisal of Northern Peatlands and Global Atmospheric Methane Over the Holocene

NASA Astrophysics Data System (ADS)

MacDonald, G. M.; Holmquist, J. R.; Kremenetski, K.; Loisel, J.

2015-12-01

Use of large databases of peat cores to examine linkages between northern peatlands and atmospheric CH4 over the Holocene has been prone to uncertainties regarding 1. comparability of radiocarbon techniques and material dated, 2. appropriate summed probability distributions, 3. spatial representativeness of the sites, particularly in capturing sites south of the subarctic, 4. potential impacts of local lateral peatland expansion versus continental-scale peatland initiation, particularly in the late Holocene, and 5. impacts of changes in the proportion of high methane-producing fens vs Sphagnum bogs. We present a comparison of radiocarbon measurements from conventional counts, atomic mass spectrometry and differing peat materials to demonstrate a general compatibility of the various types of dates. We compare and apply several summed probability distribution methods to minimize any statistical bias in our analysis. We then present our analysis of a new data set of 7571 peatland cores from 4420 sites that extend into the temperate zone. Of these, 3732 cores inform on lateral expansion and 329 dates constrain the timing of fen-bog transition. Based on these data in original and gridded form we show that widespread peat initiation commenced at 16 kcal yr BP and reached a maximum rate at 11-8 kcal yr BP. Most sites began as fens, and peak transition to bogs occurred between 5 and 3 kcal yr BP, with a 1000 year lag between Eurasia and North America. There is no global late Holocene increase in lateral expansion. Based on modeled northern peatland area and ratio of fen/bog sites, CH4 production from northern peatlands increased rapidly from 11 to 9 cal yr BP, followed by slower increase until reaching a maximum at 5 kcal yr BP at 25 Tg per yr. From 4 kcal yr BP to Present, bogs become a dominant feature in the northern peatland landscape and CH4 production decreased to reach modern-day levels at about 20 Tg per yr. Northern peatlands have been a key infleunce on global atmospheric methan variations but likely cannot account for the late Holocene increase in atmospheric CH4 experienced after 4 kcal yr BP.

In situ permafrost thaw due to climate change drives holistic microbial community shifts with implications for methane cycling

NASA Astrophysics Data System (ADS)

Mondav, Rhiannon; McCalley, Carmody; Hodgkins, Suzanne; Rich, Virginia; Frolking, Steve; Saleska, Scott; Barnes, Andrew; Chanton, Jeff; Crill, Patrick

2014-05-01

Thawing permafrost is a potentially significant source of radiative forcing feedback due to increased emissions of methane, a biogenic greenhouse gas (GHG). This study investigated changes in the microbial community along a permafrost thaw gradient at Stordalen Mire, Sweden using 16S rRNA gene amplicon and metagenomic methods. In situ measurements of geochemical parameters, including CH4 and C isotopes, enabled linkage of community dynamics to significant shifts in C balance. The thaw gradient ranged from intact at a palsa (low productivity and GHG emissions), through partially thawed in a bog (high productivity, low GHG emissions) to a completely thawed fen (high productivity and GHG emissions). Microbial assemblages in both the palsa and fen were highly diverse (in both richness and evenness), consistent with climax communities. The microbial community in the bog had distinctly lower diversity, characteristic of ecosystem disturbance. The palsa community was dominated by Acidobacteria and Proteobacteria, as is typical of a range of soils including permafrost. Methanogens dominated both the bog and fen and were most abundant within the zone of water table fluctuation. Inferring methanogens' production pathway from phylogeny showed a shift from mostly hydrogenotrophic methanogens in the bog towards acetotrophic methanogens in the fen. This corroborated porewater and flux emitted CH4 and CO2 carbon isotopic 13C signatures of CH4 and CO2. The fen, where the highest CH4 flux was recorded, was significantly richer in methanogenic archaea. A novel archaea, Candidatus Methanoflorens stordalenmirensis, was present at up to 70% relative abundance in the bog, enabling recovery of a population genome. The genome (and associated metaproteome) of 'M. stordalenmirensis' indicates that hydrogenotrophic methane production is its main energy conservation pathway. 'Methanoflorens' may be an indicator species of permafrost thaw, it is globally ubiquitous, and appears a major contributor to global methane production. Our results revealed a distinct difference in the microbial community structure and membership at each site, which can be directly associated with increasing methane emission and thaw state.

Radiometric age dating of peat cores from ombrotrophic bogs: challenges and opportunities presented by the Industrial Period

NASA Astrophysics Data System (ADS)

Shotyk, W.; Appleby, P.; Davies, L. J.; Froese, D. G.; Magnan, G.; Mullan-Boudreau, G.; Noernberg, T.; Bob, S.; van Bellen, S.; Zaccone, C.

2016-12-01

The upper layers of ombrotrophic (rain-fed) bogs are hydrologically isolated from surface waters and groundwaters and, in consequence, contaminants are supplied exclusively from the atmosphere. Peat cores from bogs have been used to reconstruct the history of heavy metal pollution since mining and metallurgy began, but the greatest changes have taken place since the start of the Industrial Revolution which was well underway by the middle of the 19th century. Dating peat, accumulated since this time has been made possible using 210Pb (t1/2 = 22.3 yr), but the validity of the age-depth relationship obtained must always be assessed using one or more chronostratigraphic markers. The post-industrial period provides an enormous range of possible time markers including various fallout radionuclides, numerous trace metals and their isotopes, and countless organic contaminants. Most of these have not yet been explored, and will be helpful only if they are immobile in the peat column; often, their fate during chemical diagenesis in anoxic, acidic bog waters is either unknown or at least poorly understood. The atmospheric bomb pulse curve of 14C for the period since AD 1950 has proved to be particularly valuable for validating 210Pb chronologies by providing accurate dates for individual plant macrofossils. Peat cores collected in northern Alberta, surrounding open pit mines and upgraders of Athabsca Bituminous Sands, were carefully dated using 210Pb and the age-depth relationship evaluated using both 241Am and 14C. The cores nearest industry (MIL, JPH4) show that atmospheric deposition of trace metals has been declining ever since industrial-scale mining and refining began in 1967. This includes all of the potentially toxic trace elements (Ag, Cd, Pb, Sb, Tl), but also the metals known for their enrichment in bitumen (V, Ni, Mo). In fact, the surface layers of these bogs today are comparable in composition to the "cleanest" peat samples ever found in the northern hemisphere. Our findings are completely opposed to recent claims about environmental pollution by metals from mining and upgrading in this region, illustrating the importance of reliable age dates and the value of robust age-depth models.

Monitoring of the active layer at Kapp Linne', SVALBARD 1972-2002

NASA Astrophysics Data System (ADS)

Akerman, J.

2003-04-01

The active layer has been monitored at ten sites in the vicinity of Kapp Linné, (78o03'42" 13o37'07") Svalbard during the period 1972 - 2002. The ten sites differ in elevation, distance from the sea, vegetation cover, substrate and active periglacial processes. From 1994 the International permafrost Association "CALM" standard grids, with measurement within 100x100m squares, has been applied. Microclimate and soil temperatures have been monitored by data logger covering levels form 2 m above to 7m below the ground. The macroclimate is covered by complete data series from the nearby weather station at Kapp Linne’, covering the period 1912 to 2002. A number of periglacial processes, especially slope processes, are monitored parallel with the active layer. The mean active layer for the sites varies between 1,13m and 0,43m. The deepest active layer is found in the exposed, well drained raised beach ridges and the shallowest in the bogs. The interannual variability during the observation period do not correlate well with the MAAT but better with the summer climate, June - August mean or DDT. The data clearly illustrate colder summers during the period 1972 to 1983 and after that steadily increasing summer temperatures. The active layer follows the same general pattern with good correlations. There are several surface indications as a response to the deepening active layer especially in the bogs. Thermokarst scars appear frequently and a majority of the palsa like mounds and pounus have disappeared. A drastic change in the vegetation on the bogs has also occurred, from dry heath to wet Carex vegetation. In summary the observations from Kapp Linne’ are; 1. A clear trend towards milder summers, 2. A clear trend towards deeper active layers, 3. All sites show a similar pattern, 4. The bogs are getting strikingly wetter, 5. Mounds in the bog sites are disappearing, 6. The slow slope processes are getting accelerated, 7. Thermokarst depressions and scars are appearing in a small scale at all sites, 8. Soil temperatures are increasing at all levels down to 7 m.

Quantification of Net Erosion and Uplift Experienced by the Barmer Basin, Rajasthan Using Sonic Log

NASA Astrophysics Data System (ADS)

Mitra, K.; Schulz, S.; Sarkar, A.

2015-12-01

Barmer Basin of Rajasthan, Western India is a hydrocarbon rich sedimentary basin currently being explored by Cairn India Limited. The hydrocarbon bearing Fatehgarh Formation is being found at different depths in different oil fields (e.g. From south to north: Guda, Vijaya & Vandana, Air field High) of the basin. The net uplift and erosion in the Barmer Basin has been quantified using compaction methodology. The sonic log, which is strongly controlled by porosity, is an appropriate indicator of compaction, and hence used for quantification of net uplift and erosion from compaction. The compaction methodology has been applied to the shale rich Dharvi Dungar Formation of Barmer Basin of Late Paleocene age. The net uplift and erosion is also being checked with the help of AFTA-VR and seismic sections. The results show relatively no uplift in the southernmost part of the basin and a Guda field well is thus taken to be the reference well with respect to which the uplifts in different parts of the basin have been calculated. The northern part of the basin i.e. Air Field High wells experienced maximum uplift (~2150m). Interestingly, a few wells further south of the reference well show evidence for uplift. The study was able to point out errors in the report produced with the help of AFTA-VR which found out less uplift in Vijaya & Vandana oil fields as opposed to sonic log data. The process of finding out uplift using sonic log has a standard deviation of 200m as compared to about 500m error in AFTA-VR method. This study has major implications for hydrocarbon exploration. Maturation of source rock will be higher for any given geothermal history if net uplift and erosion is incorporated in maturation modeling. They can also be used for porosity predictions of reservoir units in undrilled targets.

Vertical forearc tectonic displacements offer insights into underlying interplate thrust zone processes: 104-105 yr uplift/subsidence cycles in Southwest Pacific arcs may represent recoverable plastic deformation that is often falsely attributed to other causes

NASA Astrophysics Data System (ADS)

Taylor, F. W.; Lavier, L. L.; Frohlich, C.; Thirumalai, K.; Papabatu, A. K.

2015-12-01

In the forearcs of subduction zones, the characteristics of both short-term (temporary earthquake cycle) and longer-term permanent vertical deformation offer insights into processes by which plates subduct. But permanent vertical deformation may be a product of several simultaneous processes, including tectonic erosion/underplating, changing dip of the slab, upward displacement due to buoyancy or bathymetric features, and plastic shortening/extension of the forearc wedge. Here we note the rarely recognized, but possibly common, phenomenon of intermediate time scale transient vertical movements (TVM's). Both the central New Hebrides and Western Solomon forearcs have uplifted ≥500 m over time scales of 105 yr. Uplift started abruptly (over ≤10 ky) and proceeded at localized rates up to 7-8 mm/yr. Both initial uplifts terminated preceding rapid subsidence of similar dimensions and rates that, in turn, had followed yet older uplift. However, these uplifts and subsidences are superimposed on a yet longer-term trend of uplift on time scales >105 yr. The most recent uplifts extended 100-200 km along-arc and 60-90 km cross-arc while plate convergence was <10 km. These 105 yr vertical oscillations are most likely due to plastic shortening/extension driven by strong horizontal forces related to rugged seafloor bathymetry impinging on the outer forearc. Subsidence follows uplift when horizontal force abates temporarily and uplift is no longer supported by enhanced interplate coupling. Over the 105 yr time frame when interplate slip is <10 km, it is difficult to account for the timing, geography, and amounts of up and down motion by processes such as buoyancy or volumetric displacement of downgoing bathymetric features or by tectonic underplating/erosion. Instead, ~1% of shortening within the upper plate is sufficient to account for up to several hundred m of uplift across a large area of the forearc.

The peats of Costa Rica

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

Obando A, L.; Malavassi R, L.; Ramirez E, O.

The objectives of this investigation were: (1) to locate potential peat deposits in Costa Rica; (2) to estimate as closely as possible by representative sampling the amount of peat present in each deposit, and (3) to make a preliminary evaluation of the quality of the peat in each deposit. With information from soil maps and a 3-week survey of Costa Rica, it is estimated that a potential area of about 1000 km{sup 2} is covered by peat. Most of the peat area (about 830 km{sup 2}) is in northeastern Costa Rica in the Tortuguero area. An aerial survey identified themore » potential peat areas by the exclusive presence of the Yolillo palm. The next largest potential area of peat (about 175 km{sup 2}) is in the cloud-covered areas of the Talamanca Mountains. Some reconnaissance has been done in the Talamanca Mountains, and samples of the peat indicate that it is very similar to the sphagnum peat moss found in Canada and the northern US. Smaller bogs have been discovered at Medio Queso, El Cairo, Moin, and the Limon airport. Two bogs of immediate interest are Medio Queso and El Cairo. The Medio Queso bog has been extensively sampled and contains about 182,000 metric tons (dry) of highly decomposed peat, which is being used as a carrier for nitrogen-fixing bacteria. The El Cairo bog is sparsely sampled and contains about 1,300,000 metric tons of slightly decomposed dry peat. Plans are to use this peat in horticultural applications on nearby farms. 10 refs., 11 figs., 7 tabs.« less

Sphagnum-dwelling testate amoebae in subarctic bogs are more sensitive to soil warming in the growing season than in winter: the results of eight-year field climate manipulations.

PubMed

Tsyganov, Andrey N; Aerts, Rien; Nijs, Ivan; Cornelissen, Johannes H C; Beyens, Louis

2012-05-01

Sphagnum-dwelling testate amoebae are widely used in paleoclimate reconstructions as a proxy for climate-induced changes in bogs. However, the sensitivity of proxies to seasonal climate components is an important issue when interpreting proxy records. Here, we studied the effects of summer warming, winter snow addition solely and winter snow addition together with spring warming on testate amoeba assemblages after eight years of experimental field climate manipulations. All manipulations were accomplished using open top chambers in a dry blanket bog located in the sub-Arctic (Abisko, Sweden). We estimated sensitivity of abundance, diversity and assemblage structure of living and empty shell assemblages of testate amoebae in the living and decaying layers of Sphagnum. Our results show that, in a sub-arctic climate, testate amoebae are more sensitive to climate changes in the growing season than in winter. Summer warming reduced species richness and shifted assemblage composition towards predominance of xerophilous species for the living and empty shell assemblages in both layers. The higher soil temperatures during the growing season also decreased abundance of empty shells in both layers hinting at a possible increase in their decomposition rates. Thus, although possible effects of climate changes on preservation of empty shells should always be taken into account, species diversity and structure of testate amoeba assemblages in dry subarctic bogs are sensitive proxies for climatic changes during the growing season. Copyright © 2011 Elsevier GmbH. All rights reserved.

Temperature-Induced Increase in Methane Release from Peat Bogs: A Mesocosm Experiment

PubMed Central

van Winden, Julia F.; Reichart, Gert-Jan; McNamara, Niall P.; Benthien, Albert; Damsté, Jaap S. Sinninghe.

2012-01-01

Peat bogs are primarily situated at mid to high latitudes and future climatic change projections indicate that these areas may become increasingly wetter and warmer. Methane emissions from peat bogs are reduced by symbiotic methane oxidizing bacteria (methanotrophs). Higher temperatures and increasing water levels will enhance methane production, but also methane oxidation. To unravel the temperature effect on methane and carbon cycling, a set of mesocosm experiments were executed, where intact peat cores containing actively growing Sphagnum were incubated at 5, 10, 15, 20, and 25°C. After two months of incubation, methane flux measurements indicated that, at increasing temperatures, methanotrophs are not able to fully compensate for the increasing methane production by methanogens. Net methane fluxes showed a strong temperature-dependence, with higher methane fluxes at higher temperatures. After removal of Sphagnum, methane fluxes were higher, increasing with increasing temperature. This indicates that the methanotrophs associated with Sphagnum plants play an important role in limiting the net methane flux from peat. Methanotrophs appear to consume almost all methane transported through diffusion between 5 and 15°C. Still, even though methane consumption increased with increasing temperature, the higher fluxes from the methane producing microbes could not be balanced by methanotrophic activity. The efficiency of the Sphagnum-methanotroph consortium as a filter for methane escape thus decreases with increasing temperature. Whereas 98% of the produced methane is retained at 5°C, this drops to approximately 50% at 25°C. This implies that warming at the mid to high latitudes may be enhanced through increased methane release from peat bogs. PMID:22768100

The complex relationships between methane emissions and water table at an ombrotrophic bog

NASA Astrophysics Data System (ADS)

Humphreys, Elyn; Roulet, Nigel; Moore, Tim

2017-04-01

Broad spatial and temporal variations in methane emissions from peatlands have been related to many variables including water table position, temperature and vegetation characteristics and functioning. In general, wetter peatlands tend to have greater methane emissions. However, over shorter periods of time and space, the relationship between water table and methane emissions can reverse, show hysteresis or be absent entirely. These relationships are investigated at the Mer Bleue Bog, a temperate ombrotrophic bog near Ottawa, Canada. Six years of concurrent growing season eddy covariance and automated chamber fluxes reveal the expected broad patterns. During the wettest growing season, the water table remained within 40 cm of the bog's hummock surfaces. Methane emissions were upwards of 20 to 45 mg C m-2 d-1 and exceeded the emission rates from two drier growing seasons which saw periods where the water table dropped to nearly 80 cm below the hummock surface. In those periods, methane emission rates declined to about 5 mg C m-2 d-1 or less. Lawn plots with aerenchymatous Eriophorum vegetation and high water tables had greatest emissions (exceeding 200 mg C m-2 d-1) compared to hummock plots vegetated by ericaceous shrubs, which had emissions rates similar to those measured by eddy covariance. However, within a growing season, hysteresis and inverse relationships between water table and methane emissions were observed at both ecosystem and chamber plot scales. These included periods between rainfall events where methane emissions increased while the water table deepened. The potential roles of methane production, consumption, storage and transport processes on these patterns will be discussed.

Research Spotlight: Extraordinary uplift of Yellowstone caldera

NASA Astrophysics Data System (ADS)

Tretkoff, Ernie

2011-02-01

In Yellowstone National Park, located in Wyoming, Montana, and Idaho, the Yellow­stone caldera, which extends about 40 kilometers by 60 kilometers, began in 2004 a period of accelerated uplift, with rates of uplift as high as 7 centimeters per year. From 2006 to 2009 the uplift rate slowed. Global Positioning System (GPS) and interferometric synthetic aperture radar (InSAR) ground deformation measurements described by Chang et al. show that in the northern caldera, uplift decreased from 7 centimeters per year in 2006 to 5 in 2008 and 2 in 2009. In the southwestern portion of the caldera, uplift decreased from 4 centimeters per year in 2006 to 2 in 2008 and 0.5 in 2009, demonstrating a spatial pattern of ground motion decrease from southwest to northeast along the caldera. (”Geophysical Research Letters, doi:10.1029/2010GL045451, 2010)

Spatial and temporal variation of tectonic uplift in the southeastern Ethiopian Plateau from morphotectonic analysis

NASA Astrophysics Data System (ADS)

Xue, Liang; Alemu, Tadesse; Gani, Nahid D.; Abdelsalam, Mohamed G.

2018-05-01

We use morphotectonic analysis to study the tectonic uplift history of the southeastern Ethiopian Plateau (SEEP). Based on studies conducted on the Northwestern Ethiopian Plateau, steady-state and pulsed tectonic uplift models were proposed to explain the growth of the plateau since 30 Ma. We test these two models for the largely unknown SEEP. We present the first quantitative morphotectonic study of the SEEP. First, in order to infer the spatial distribution of the tectonic uplift rates, we extract geomorphic proxies including normalized steepness index ksn, hypsometric integral HI, and chi integral χ from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) digital elevation model (DEM). Second, we compare these rates with the thickness of flood basalt that we estimated from geological maps. Third, to constrain the timing of regional tectonic uplift, we develop a knickpoint celerity model. Fourth, we compare our results to those from the Northwestern Ethiopian Plateau to suggest a possible mechanism to explain regional tectonic uplift of the entire Ethiopian Plateau. We find an increase in tectonic uplift rates from the southeastern escarpments of the Afar Depression in the northeast to that of the Main Ethiopian Rift to the southwest. We identify three regional tectonic uplift events at 11.7, 6.5, and 4.5 Ma recorded by the development of regionally distributed knickpoints. This is in good agreement with ages of tectonic uplift events reported from the Northwestern Ethiopian Plateau.

Can footwall unloading explain late Cenozoic uplift of the Sierra Nevada crest?

USGS Publications Warehouse

Thompson, G.A.; Parsons, T.

2009-01-01

Globally, normal-fault displacement bends and warps rift flanks upwards, as adjoining basins drop downwards. Perhaps the most evident manifestations are the flanks of the East African Rift, which cuts across the otherwise minimally deformed continent. Flank uplift was explained by Vening Meinesz (1950, Institut Royal Colonial Belge, Bulletin des Seances, v. 21, p. 539-552), who recognized that isostasy should cause uplift of a normal-faulted footwall and subsidence of its hanging wall. Uplift occurs because slip on a dipping normal fault creates a broader root of less-dense material beneath the footwall, and a narrowed one beneath the hanging wall. In this paper, we investigate the potential influence of this process on the latest stages of Sierra Nevada uplift. Through theoretical calculations and 3D finite element modelling, we find that cumulative slip of about 4km on range-front faults would have produced about 1.3km peak isostatic uplift at the ridge crest. Numerical models suggest that the zone of uplift is narrow, with the width controlled by bending resistance of the seismogenic crust. We conclude that footwall unloading cannot account for the entire elevation of the Sierran crest above sea level, but if range-front faulting initiated in an already elevated plateau like the adjacent Basin and Range Province, then a hybrid model of pre-existing regional uplift and localized footwall unloading can account for the older and newer uplift phases suggested by the geologic record.

GPS Imaging of vertical land motion in California and Nevada: Implications for Sierra Nevada uplift

NASA Astrophysics Data System (ADS)

Hammond, William C.; Blewitt, Geoffrey; Kreemer, Corné

2016-10-01

We introduce Global Positioning System (GPS) Imaging, a new technique for robust estimation of the vertical velocity field of the Earth's surface, and apply it to the Sierra Nevada Mountain range in the western United States. Starting with vertical position time series from Global Positioning System (GPS) stations, we first estimate vertical velocities using the MIDAS robust trend estimator, which is insensitive to undocumented steps, outliers, seasonality, and heteroscedasticity. Using the Delaunay triangulation of station locations, we then apply a weighted median spatial filter to remove velocity outliers and enhance signals common to multiple stations. Finally, we interpolate the data using weighted median estimation on a grid. The resulting velocity field is temporally and spatially robust and edges in the field remain sharp. Results from data spanning 5-20 years show that the Sierra Nevada is the most rapid and extensive uplift feature in the western United States, rising up to 2 mm/yr along most of the range. The uplift is juxtaposed against domains of subsidence attributable to groundwater withdrawal in California's Central Valley. The uplift boundary is consistently stationary, although uplift is faster over the 2011-2016 period of drought. Uplift patterns are consistent with groundwater extraction and concomitant elastic bedrock uplift, plus slower background tectonic uplift. A discontinuity in the velocity field across the southeastern edge of the Sierra Nevada reveals a contrast in lithospheric strength, suggesting a relationship between late Cenozoic uplift of the southern Sierra Nevada and evolution of the southern Walker Lane.

Multi-omics of permafrost, active layer and thermokarst bog soil microbiomes

NASA Astrophysics Data System (ADS)

Hultman, Jenni; Waldrop, Mark P.; Mackelprang, Rachel; David, Maude M.; McFarland, Jack; Blazewicz, Steven J.; Harden, Jennifer; Turetsky, Merritt R.; McGuire, A. David; Shah, Manesh B.; Verberkmoes, Nathan C.; Lee, Lang Ho; Mavrommatis, Kostas; Jansson, Janet K.

2015-05-01

Over 20% of Earth's terrestrial surface is underlain by permafrost with vast stores of carbon that, once thawed, may represent the largest future transfer of carbon from the biosphere to the atmosphere. This process is largely dependent on microbial responses, but we know little about microbial activity in intact, let alone in thawing, permafrost. Molecular approaches have recently revealed the identities and functional gene composition of microorganisms in some permafrost soils and a rapid shift in functional gene composition during short-term thaw experiments. However, the fate of permafrost carbon depends on climatic, hydrological and microbial responses to thaw at decadal scales. Here we use the combination of several molecular `omics' approaches to determine the phylogenetic composition of the microbial communities, including several draft genomes of novel species, their functional potential and activity in soils representing different states of thaw: intact permafrost, seasonally thawed active layer and thermokarst bog. The multi-omics strategy reveals a good correlation of process rates to omics data for dominant processes, such as methanogenesis in the bog, as well as novel survival strategies for potentially active microbes in permafrost.

Drainage and fertilization effects on nutrient availability in an ombrotrophic peatland.

PubMed

Wang, Meng; Talbot, Julie; Moore, Tim R

2018-04-15

Nutrient availability is an important control on the vegetation distribution, productivity and functioning of peatland ecosystems and we examined spatial and temporal patterns of nutrient availability through ion exchange at Mer Bleue bog, southeast Ontario, Canada. We installed ion exchange probes at 5-15cm for 4weeks and determined nutrient sorption at undisturbed sites as well as those affected by nitrogen (N), phosphorus (P), potassium (K) fertilization and drainage. Under undisturbed conditions, the bog had very small amount of available nutrients, especially N (ammonium>nitrate) and P, and exhibited small variations in nutrient availability during the growing season (May to October). The increase in NPK availability upon fertilization was short-lived over the season and the stoichiometry of available NPK captured by the probes was mismatched with the vegetation. The increase in nutrient availability with drainage was confounded by substantial changes in vegetation. We compare these results with data from other Canadian bogs and fens to provide baseline data on nutrient availability in peatlands. Copyright © 2017 Elsevier B.V. All rights reserved.

Groundwater flow with energy transport and water-ice phase change: Numerical simulations, benchmarks, and application to freezing in peat bogs

USGS Publications Warehouse

McKenzie, J.M.; Voss, C.I.; Siegel, D.I.

2007-01-01

In northern peatlands, subsurface ice formation is an important process that can control heat transport, groundwater flow, and biological activity. Temperature was measured over one and a half years in a vertical profile in the Red Lake Bog, Minnesota. To successfully simulate the transport of heat within the peat profile, the U.S. Geological Survey's SUTRA computer code was modified. The modified code simulates fully saturated, coupled porewater-energy transport, with freezing and melting porewater, and includes proportional heat capacity and thermal conductivity of water and ice, decreasing matrix permeability due to ice formation, and latent heat. The model is verified by correctly simulating the Lunardini analytical solution for ice formation in a porous medium with a mixed ice-water zone. The modified SUTRA model correctly simulates the temperature and ice distributions in the peat bog. Two possible benchmark problems for groundwater and energy transport with ice formation and melting are proposed that may be used by other researchers for code comparison. ?? 2006 Elsevier Ltd. All rights reserved.

Multi-omics of permafrost, active layer and thermokarst bog soil microbiomes.

PubMed

Hultman, Jenni; Waldrop, Mark P; Mackelprang, Rachel; David, Maude M; McFarland, Jack; Blazewicz, Steven J; Harden, Jennifer; Turetsky, Merritt R; McGuire, A David; Shah, Manesh B; VerBerkmoes, Nathan C; Lee, Lang Ho; Mavrommatis, Kostas; Jansson, Janet K

2015-05-14

Over 20% of Earth's terrestrial surface is underlain by permafrost with vast stores of carbon that, once thawed, may represent the largest future transfer of carbon from the biosphere to the atmosphere. This process is largely dependent on microbial responses, but we know little about microbial activity in intact, let alone in thawing, permafrost. Molecular approaches have recently revealed the identities and functional gene composition of microorganisms in some permafrost soils and a rapid shift in functional gene composition during short-term thaw experiments. However, the fate of permafrost carbon depends on climatic, hydrological and microbial responses to thaw at decadal scales. Here we use the combination of several molecular 'omics' approaches to determine the phylogenetic composition of the microbial communities, including several draft genomes of novel species, their functional potential and activity in soils representing different states of thaw: intact permafrost, seasonally thawed active layer and thermokarst bog. The multi-omics strategy reveals a good correlation of process rates to omics data for dominant processes, such as methanogenesis in the bog, as well as novel survival strategies for potentially active microbes in permafrost.

Functioning of microbial complexes in aerated layers of a highmoor peat bog

NASA Astrophysics Data System (ADS)

Golovchenko, A. V.; Bogdanova, O. Yu.; Stepanov, A. L.; Polyanskaya, L. M.; Zvyagintsev, D. G.

2010-09-01

Monitoring was carried out using the luminescent-microscopic method of the abundance parameters of different groups of microorganisms in a monolith and in the mixed layers of a highmoor peat bog (oligotrophic residual-eutrophic peat soil) in a year-long model experiment. The increase of the aeration as a result of mixing of the layers enhanced the activity of the soil fungi. This was attested to by the following changes: the increase of the fungal mycelium length by 6 times and of the fungal biomass by 4 times and the double decrease of the fraction of spores in the fungal complex. The response of the fungal complex to mixing was different in the different layers of the peat bog. The maximal effect was observed in the T1 layer and the minimal one in the T2 layer. The emission of CO2 in the mixed samples was 1.5-2 times higher than that from the undisturbed peat samples. In contrast with the fungi, the bacteria and actinomycetes were not affected by the aeration of the highmoor layers.

Regional uplift associated with continental large igneous provinces: The roles of mantle plumes and the lithosphere

USGS Publications Warehouse

Saunders, A.D.; Jones, S.M.; Morgan, L.A.; Pierce, K.L.; Widdowson, M.; Xu, Y.G.

2007-01-01

The timing and duration of surface uplift associated with large igneous provinces provide important constraints on mantle convection processes. Here we review geological indicators of surface uplift associated with five continent-based magmatic provinces: Emeishan Traps (260??million years ago: Ma), Siberian Traps (251??Ma), Deccan Traps (65??Ma), North Atlantic (Phase 1, 61??Ma and Phase 2, 55??Ma), and Yellowstone (16??Ma to recent). All five magmatic provinces were associated with surface uplift. Surface uplift can be measured directly from sedimentary indicators of sea-level in the North Atlantic and from geomorpholocial indicators of relative uplift and tilting in Yellowstone. In the other provinces, surface uplift is inferred from the record of erosion. In the Deccan, North Atlantic and Emeishan provinces, transient uplift that results from variations in thermal structure of the lithosphere and underlying mantle can be distinguished from permanent uplift that results from the extraction and emplacement of magma. Transient surface uplift is more useful in constraining mantle convection since models of melt generation and emplacement are not required for its interpretation. Observations of the spatial and temporal relationships between surface uplift, rifting and magmatism are also important in constraining models of LIP formation. Onset of surface uplift preceded magmatism in all five of the provinces. Biostratigraphic constraints on timing of uplift and erosion are best for the North Atlantic and Emeishan Provinces, where the time interval between significant uplift and first magmatism is less than 1??million years and 2.5??million years respectively. Rifting post-dates the earliest magmatism in the case of the North Atlantic Phase 1 and possibly in the case of Siberia. The relative age of onset of offshore rifting is not well constrained for the Deccan and the importance of rifting in controlling magmatism is disputed in the Emeishan and Yellowstone Provinces. In these examples, rifting is not a requirement for onset of LIP magmatism but melting rates are significantly increased when rifting occurs. Models that attempt to explain emplacement of these five LIPs without hot mantle supplied by mantle plumes often have difficulties in explaining the observations of surface uplift, rifting and magmatism. For example, small-scale convection related to craton or rift boundaries (edge-driven convection) cannot easily explain widespread (1000??km scale) transient surface uplift (Emeishan, Deccan, North Atlantic), and upper mantle convection initiated by differential incubation beneath cratons (the hotcell model) is at odds with rapid onset of surface uplift (Emeishan, North Atlantic). The start-up plume concept is still the most parsimonious way of explaining the observations presented here. However, observations of surface uplift cannot directly constrain the depth of origin of the hot mantle in a plume head. The short time interval between onset of transient surface uplift and magmatism in the North Atlantic and Emeishan means that the associated starting plume heads were probably not large (??? 1000??km diameter) roughly spherical diapirs and are likely to have formed narrow (??? 100??km radius) upwelling jets, with hot mantle then spreading rapidly outward within the asthenosphere. In cases where rifting post-dates magmatism (N Atlantic Phase 1) or where the degree of lithospheric extension may not have been great (Siberia), a secondary mechanism of lithospheric thinning, such as gravitational instability or delamination of the lower lithosphere, may be required to allow hot mantle to decompress sufficiently to explain the observed volume of magma with a shallow melting geochemical signature. Any such additional thinning mechanisms are probably a direct consequence of plume head emplacement. ?? 2007 Elsevier B.V. All rights reserved.

Role of erosion and isostasy in the Cordillera Blanca uplift: Insights from landscape evolution modeling (northern Peru, Andes)

NASA Astrophysics Data System (ADS)

Margirier, Audrey; Braun, Jean; Robert, Xavier; Audin, Laurence

2018-03-01

The processes driving uplift and exhumation of the highest Peruvian peaks (the Cordillera Blanca) are not well understood. Uplift and exhumation seem closely linked to the formation and movement on the Cordillera Blanca normal fault (CBNF) that delimits and shapes the western flank of the Cordillera Blanca. Several models have been proposed to explain the presence of this major normal fault in a compressional setting, but the CBNF and the Cordillera Blanca recent rapid uplift remain enigmatic. Whereas the Cordillera Blanca morphology demonstrates important erosion and thus a significant mass of rocks removal, the impact of erosion and isostasy on the evolution of the Cordillera Blanca uplift rates has never been explored. We address the role of erosion and associated flexural rebound in the uplift and exhumation of the Cordillera Blanca with numerical modeling of landscape evolution. We perform inversions of the broad features of the present-day topography, total exhumation and thermochronological data using a landscape evolution model (FastScape) to provide constraints on the erosion efficiency factor, the uplift rate and the temperature gradient. Our results evidence the not negligible contribution of erosion and associated flexural rebound to the uplift of the Cordillera Blanca and allow us to question the models previously proposed for the formation of the CBNF.

Geophysical investigations of the tectonic boundary between East and West Antarctica

USGS Publications Warehouse

ten Brink, Uri S.; Bannister, S.; Beaudoin, B.C.; Stern, T.A.

1993-01-01

The Transantarctic Mountains (TAM), which separate the West Antarctic rift system from the stable shield of East Antarctica, are the largest mountains developed adjacent to a rift. The cause of uplift of mountains bordering rifts is poorly understood. One notion based on observations of troughs next to many uplifted blocks is that isostatic rebound produces a coeval uplift and subsidence. The results of an over-snow seismic experiment in Antarctica do not show evidence for a trough next to the TAM but indicate the extension of rifted mantle lithosphere under the TAM. Furthermore, stretching preceded the initiation of uplift, which suggests thermal buoyancy as the cause for uplift.

Modern Uplift of the Transantarctic Mountains: Preliminary Results of an Autonomous GPS Array

NASA Technical Reports Server (NTRS)

Raymond, C. A.; Heflin, M. B.; Ivins, E. R.; James, T. S.

1998-01-01

An autonomous GPS array is being implemented in the Transantarctic Mountains, sponsored by NSF and NASA, for the purpose of measuring uplift resulting from post-glacial rebound (PGR). The rebound of the solid earth due to unloading of ice since the Last Glacial Maximum is expected to dominate the measured uplift for most of West Antarctica, dwarfing the signals due to present-day ice sheet mass balance changes and tectonic motion, as long as mantle viscosity is greater than about 10(exp 20) Pa-s. Predicted uplift patterns have been calculated for a range of model scenarios, which illustrate how the uplift pattern might distinguish between different-sized ice sheets and deglaciation histories as represented by the competing models. The scenarios considered by James and Ivins (1998) include ICE-3G, CLIMAP and a variation of the CLIMAP model by Denton et al. For these models, peak uplift rates occur in the Transantarctic Mountains, and differences between models is often large there. Thus, the Transantarctic Mountains are an ideal place to obtain uplift measurements to constrain deglaciation models.

Sediment geochemistry as potential sea-level indicators to assess coseismic vertical displacements above the Alaska-Aleutian megathrust

NASA Astrophysics Data System (ADS)

Bender, A. M.; Witter, R. C.; Munk, L. A.

2012-12-01

Nearly the entire 4000-km-long Alaska-Aleutian megathrust has ruptured in large or great (Mw ≥8) earthquakes in the past 100 years, yet paleoseismic records of earlier events are only documented east of Kodiak Is. in the region of the 1964 Alaska earthquake. The Mw 9.2 1964 earthquake dropped the coast along Cook Inlet and Turnagain Arm by ≤1.8 m and raised shore platforms around Prince William Sound by ≤3 m. Evidence of sudden (coseismic) vertical displacements during megathrust earthquakes are archived in coastal sediments as sharp stratigraphic contacts that record rapid relative sea-level (RSL) changes. We use geochemical analyses of coastal sediments to detect sudden RSL changes at 2 sites above the Alaska-Aleutian megathrust. One site on Knik Arm near Anchorage subsided ~0.6 m during the 1964 earthquake. The other site overlies the Shumagin Islands segment of the megathrust, without rupture since before 1903. Relative to terrestrial sources of sediment, marine sources should be enriched in δ13C, δ15N, and have higher C:N, and Cl- concentrations. Our analyses will test whether these geochemical proxies can provide evidence for sudden RSL change across stratigraphic contacts that record coseismic uplift or subsidence. Coseismic subsidence should be represented by contacts that place sediment with enriched δ13C, δ15N signatures, elevated C:N and Cl- concentrations over sediment with lower values of these geochemical proxies and the reverse for coseismic uplift. A 1-2 m tall, ~0.5-km-long bluff along Knik Arm exposes three buried wetland soils overlain by gray mud. The soils become faint and pinch out to the northeast near a large tidal channel. Other studies of similar buried soils at adjacent sites suggest the youngest soil at Knik Arm subsided in 1964. 14C analyses of plant fossils in two older soils will provide age estimates for earlier events. We will apply the proposed geochemical methods to 20 samples collected along a forested upland to tidal mud flat transect to distinguish terrestrial from marine sediment. On Simeonof Is., stratigraphy beneath a peat bog adjacent to a tidal lagoon consists of basal marine sand overlain by ~0.6-1.5 m of peat. The presence of Arachnoidiscus japonicas, benthic marine diatom, implies a marine sand source. Sphagnum spp. and absence of marine foraminifera indicate freshwater peat. We analyzed δ13C, δ15N, and C:N from bulk sediment, and Cl- from water soluble fraction of sediment in a 1.3-m bog core. Freshwater peat at depths of 0.0-26.0, and 33.0-78.5 cm have δ13C ranging from -25.02 to -27.35 ‰, δ15N from 3.30-9.93‰, C:N of 10.16-17.89, and Cl- concentrations of 0.9-25.9 mg/L. Sand dominated intervals at 26.0-33.0, and 78.5-130 cm have δ13C ranging from -17.24 to -26.50‰, δ15N from 8.30-11.11‰ , C:N of 0.30-29.6 and Cl- concentrations of 0.7-19.3 mg/L. The data also indicate that average δ13C and δ15N values are enriched in marine sand relative to freshwater peat, respectively by 3.27‰ and 3.10‰. Also C:N ratios and Cl- concentrations are lower in marine sand, respectively by 23.1 and 0.1 mg/L. Hence, δ13C and δ15N show promise as geochemical proxies to distinguish terrestrial from marine sediment for future Alaska-Aleutian paleoseismic studies west of Kodiak Is.

Terrain Analysis Procedural Guide for Soil. Report Number 6 in the ETL Series on Guides for Army Terrain Analysts

DTIC Science & Technology

1981-02-01

01 T3 Swamp Pt. OH. CH. MH. OL T4 Peat Bog Pt T5 . - Peat Cuttings Pt T6 Cranberry Bog Pt. OH. CH. MH, OL T7 Rice holds Pt. OH, CH, MH, OL ’ ~Known...Commonly Associated Soils Landlorm/erc Climate Horizon USCS Symbol Coastal Plain unspecified unspecified OL. ML. CL. ML-CL, MH. Depressions CH, OH...total sample. SALINA A salt marsh or pond located adjacent to the sea, but not open to the sea. SALT PAN Any flat area or natural depression where water

Glacial isostatic uplift of the European Alps

PubMed Central

Mey, Jürgen; Scherler, Dirk; Wickert, Andrew D.; Egholm, David L.; Tesauro, Magdala; Schildgen, Taylor F.; Strecker, Manfred R.

2016-01-01

Following the last glacial maximum (LGM), the demise of continental ice sheets induced crustal rebound in tectonically stable regions of North America and Scandinavia that is still ongoing. Unlike the ice sheets, the Alpine ice cap developed in an orogen where the measured uplift is potentially attributed to tectonic shortening, lithospheric delamination and unloading due to deglaciation and erosion. Here we show that ∼90% of the geodetically measured rock uplift in the Alps can be explained by the Earth’s viscoelastic response to LGM deglaciation. We modelled rock uplift by reconstructing the Alpine ice cap, while accounting for postglacial erosion, sediment deposition and spatial variations in lithospheric rigidity. Clusters of excessive uplift in the Rhône Valley and in the Eastern Alps delineate regions potentially affected by mantle processes, crustal heterogeneity and active tectonics. Our study shows that even small LGM ice caps can dominate present-day rock uplift in tectonically active regions. PMID:27830704

Glacial isostatic uplift of the European Alps.

PubMed

Mey, Jürgen; Scherler, Dirk; Wickert, Andrew D; Egholm, David L; Tesauro, Magdala; Schildgen, Taylor F; Strecker, Manfred R

2016-11-10

Following the last glacial maximum (LGM), the demise of continental ice sheets induced crustal rebound in tectonically stable regions of North America and Scandinavia that is still ongoing. Unlike the ice sheets, the Alpine ice cap developed in an orogen where the measured uplift is potentially attributed to tectonic shortening, lithospheric delamination and unloading due to deglaciation and erosion. Here we show that ∼90% of the geodetically measured rock uplift in the Alps can be explained by the Earth's viscoelastic response to LGM deglaciation. We modelled rock uplift by reconstructing the Alpine ice cap, while accounting for postglacial erosion, sediment deposition and spatial variations in lithospheric rigidity. Clusters of excessive uplift in the Rhône Valley and in the Eastern Alps delineate regions potentially affected by mantle processes, crustal heterogeneity and active tectonics. Our study shows that even small LGM ice caps can dominate present-day rock uplift in tectonically active regions.

Growing the Anatolian plateau: Coupled tectonic deformation and lithospheric slab dynamics

NASA Astrophysics Data System (ADS)

Schildgen, T. F.; Cosentino, D.; Yildirim, C.; Echtler, H.; Strecker, M. R.

2011-12-01

The Anatolian plateau marks the western end of the high topography associated with collision of the African and Arabian plates with Eurasia. The Eastern and Central Anatolian plateaus have been considered separate entities, with crustal shortening in the east resulting in a 1.5- to 2.5-km high and more rugged plateau compared to the strike-slip bounded, 1- to 1.5-km high, relatively undeformed plateau in the west. Uplift mechanisms for the Eastern Anatolian plateau have been discussed for decades, and a mounting body of evidence supports an important role of both crustal shortening and lithospheric slab dynamics. In contrast, fewer studies have been focused on Central Anatolia. Our recent data constraining the timing, magnitude, pattern, and style of uplift in Central Anatolia helps not only to elucidate details of what may be an early stage in orogenic plateau development, but also highlights ways in which the two plateau realms may be closely linked. Approaches to determining paleoaltimetry in Central Anatolia differ from those in other major orogenic plateaus, as its modest elevations and low Neogene exhumation imply that stable isotope and thermochronological methods have limited applicability. Nonetheless, sedimentary basins within the plateau interior, preserved along the high-relief margins, and in basins flanking the plateau archive the deformation and uplift history, particularly where the uplifted strata include fossil-rich marine sediments. Combined with manifestations of river incision in response to surface uplift, these deposits offer one of the world's best-constrained records of long-term, km-scale surface uplift. However, assessing uplift along the plateau margins is complex, because the timing of the 1 to 1.5 km lowering of sea level in the Mediterranean and Black seas during the Messinian Salinity Crisis overlaps with the onset of regional surface uplift. Although a number of major questions remain concerning the relative timing of uplift of Eastern and Central Anatolia, how sea-level lowering and climate change affected records interpreted as an uplift signal, and to what extent upper mantle processes can be linked to surface uplift patterns, both the Central and Eastern Anatolia appear to have been impacted by lithospheric slab dynamics. Specifically, uplift of the southern margin of Central Anatolia starting between 7 and 5.45 Ma appears to postdate uplift of Eastern Anatolia, which may be explained by slab break-off and tearing that initiated in the east and subsequently propagated westward. In contrast to the processes forcing plateau uplift along the southern flank, we link growth of the northern margin of Central Anatolia to westward extrusion of the Anatolian microplate and the restraining bend in the North Anatolian Fault. These disparate underlying mechansims may be linked if the evolution of the subducting lithospheric slab helped to initiate westward extrusion of Central Anatolia.

GPS Imaging of vertical land motion in California and Nevada: Implications for Sierra Nevada uplift

PubMed Central

Blewitt, Geoffrey; Kreemer, Corné

2016-01-01

Abstract We introduce Global Positioning System (GPS) Imaging, a new technique for robust estimation of the vertical velocity field of the Earth's surface, and apply it to the Sierra Nevada Mountain range in the western United States. Starting with vertical position time series from Global Positioning System (GPS) stations, we first estimate vertical velocities using the MIDAS robust trend estimator, which is insensitive to undocumented steps, outliers, seasonality, and heteroscedasticity. Using the Delaunay triangulation of station locations, we then apply a weighted median spatial filter to remove velocity outliers and enhance signals common to multiple stations. Finally, we interpolate the data using weighted median estimation on a grid. The resulting velocity field is temporally and spatially robust and edges in the field remain sharp. Results from data spanning 5–20 years show that the Sierra Nevada is the most rapid and extensive uplift feature in the western United States, rising up to 2 mm/yr along most of the range. The uplift is juxtaposed against domains of subsidence attributable to groundwater withdrawal in California's Central Valley. The uplift boundary is consistently stationary, although uplift is faster over the 2011–2016 period of drought. Uplift patterns are consistent with groundwater extraction and concomitant elastic bedrock uplift, plus slower background tectonic uplift. A discontinuity in the velocity field across the southeastern edge of the Sierra Nevada reveals a contrast in lithospheric strength, suggesting a relationship between late Cenozoic uplift of the southern Sierra Nevada and evolution of the southern Walker Lane. PMID:27917328

GPS Imaging of vertical land motion in California and Nevada: Implications for Sierra Nevada uplift.

PubMed

Hammond, William C; Blewitt, Geoffrey; Kreemer, Corné

2016-10-01

We introduce Global Positioning System (GPS) Imaging, a new technique for robust estimation of the vertical velocity field of the Earth's surface, and apply it to the Sierra Nevada Mountain range in the western United States. Starting with vertical position time series from Global Positioning System (GPS) stations, we first estimate vertical velocities using the MIDAS robust trend estimator, which is insensitive to undocumented steps, outliers, seasonality, and heteroscedasticity. Using the Delaunay triangulation of station locations, we then apply a weighted median spatial filter to remove velocity outliers and enhance signals common to multiple stations. Finally, we interpolate the data using weighted median estimation on a grid. The resulting velocity field is temporally and spatially robust and edges in the field remain sharp. Results from data spanning 5-20 years show that the Sierra Nevada is the most rapid and extensive uplift feature in the western United States, rising up to 2 mm/yr along most of the range. The uplift is juxtaposed against domains of subsidence attributable to groundwater withdrawal in California's Central Valley. The uplift boundary is consistently stationary, although uplift is faster over the 2011-2016 period of drought. Uplift patterns are consistent with groundwater extraction and concomitant elastic bedrock uplift, plus slower background tectonic uplift. A discontinuity in the velocity field across the southeastern edge of the Sierra Nevada reveals a contrast in lithospheric strength, suggesting a relationship between late Cenozoic uplift of the southern Sierra Nevada and evolution of the southern Walker Lane.

Analysis of Microbial Community Composition and Methane Production From Northern Peatlands Across a Climate Gradient

NASA Astrophysics Data System (ADS)

Sarno, A. F.; Humphreys, E.; Olefeldt, D.; Heffernan, L.; Roman, T. D.; Sebestyen, S.; Kolka, R.; Yavitt, J. B.; Finn, D.; Cadillo-Quiroz, H.

2017-12-01

Northern peatland ecosystems allow for the accumulation of a carbon (C) pool as the rate of photosynthesis exceeds the rate of organic carbon decomposition. Under current climate conditions, many northern peatlands act as a C sink; however, changes in climate and other environmental conditions, such as soil permafrost melting, are capable of changing the decomposition cascade. Here we take advantage of four peatlands situated along a climate gradient from tundra (Daring Lake, Canada) to boreal forest (Lutose, Canada) to temperate broadleaf and mixed forest (Bog Lake, MN and Chicago Bog, NY) biomes to assess how the relative abundance of microbial functional groups and substrate availability within the microbial community might impact the decomposition of soil organic matter to methane. The four peatlands had similar hydrology and geochemistry and were poor fen types. Soil, water and gas samples were collected at the water table level. Microbial community composition, derived from Illumina amplicon sequencing of the 16S rRNA gene, and geochemical and climate variables were analyzed with principal component regression analysis to determine major drivers of community variation. Mean annual temperature (r2=0.53), mean annual precipitation (r2=0.36), water table level (r2=0.43) and soil temperature (r2=0.49), were all statistically significant drivers of both general microbial and methanogen community composition (p value < 0.001). The relative abundance of Methanocella, Methanosarcina and Methanobacterium varied significantly across the climate gradient (p value < 0.05), however the majority of methanogen genera did not. Interestingly, dissolved methane (r2=0.24) was statistically significant at the general community level (p value < 0.001), but not significant when tested against only the methanogen community. The results demonstrate that environmental factors predicted to change over time due to climate change will have a significant impact on microbial community composition and C sinks within Northern peatlands. Further analyses of microbial processes that produce methanogenic substrates such as fermentation and syntrophic reactions, in tandem with the further identification and quantification of methanogens, will elucidate other drivers of methane production in Northern peatlands.

Peatland classification of West Siberia based on Landsat imagery

NASA Astrophysics Data System (ADS)

Terentieva, I.; Glagolev, M.; Lapshina, E.; Maksyutov, S. S.

2014-12-01

Increasing interest in peatlands for prediction of environmental changes requires an understanding of its geographical distribution. West Siberia Plain is the biggest peatland area in Eurasia and is situated in the high latitudes experiencing enhanced rate of climate change. West Siberian taiga mires are important globally, accounting for about 12.5% of the global wetland area. A number of peatland maps of the West Siberia was developed in 1970s, but their accuracy is limited. Here we report the effort in mapping West Siberian peatlands using 30 m resolution Landsat imagery. As a first step, peatland classification scheme oriented on environmental parameter upscaling was developed. The overall workflow involves data pre-processing, training data collection, image classification on a scene-by-scene basis, regrouping of the derived classes into final peatland types and accuracy assessment. To avoid misclassification peatlands were distinguished from other landscapes using threshold method: for each scene, Green-Red Vegetation Indices was used for peatland masking and 5th channel was used for masking water bodies. Peatland image masks were made in Quantum GIS, filtered in MATLAB and then classified in Multispec (Purdue Research Foundation) using maximum likelihood algorithm of supervised classification method. Training sample selection was mostly based on spectral signatures due to limited ancillary and high-resolution image data. As an additional source of information, we applied our field knowledge resulting from more than 10 years of fieldwork in West Siberia summarized in an extensive dataset of botanical relevés, field photos, pH and electrical conductivity data from 40 test sites. After the classification procedure, discriminated spectral classes were generalized into 12 peatland types. Overall accuracy assessment was based on 439 randomly assigned test sites showing final map accuracy was 80%. Total peatland area was estimated at 73.0 Mha. Various ridge-hollow and ridge-hollow-pool bog complexes prevail here occupying 34.5 Mha. They are followed by lakes (11.1 Mha), fens (10.7 Mha), pine-dwarf-shrub sphagnum bogs (9.3 Mha) and palsa complexes (7.4 Mha).

An ecohydrological sketch of climate change impacts on water and natural ecosystems for the Netherlands: bridging the gap between science and society

NASA Astrophysics Data System (ADS)

Witte, J. P. M.; Runhaar, J.; van Ek, R.; van der Hoek, D. C. J.; Bartholomeus, R. P.; Batelaan, O.; van Bodegom, P. M.; Wassen, M. J.; van der Zee, S. E. A. T. M.

2012-11-01

For policy making and spatial planning, information is needed about the impacts of climate change on natural ecosystems. To provide this information, commonly hydrological and ecological models are used. We give arguments for our assessment that modelling only is insufficient for determining the impacts of climate changes on natural ecosystems at regional scales. Instead, we proposed a combination of hydrological simulations, a literature review and process-knowledge on climate-hydrology-vegetation interactions, to compile a sketch map that indicates climate change effects on a number of ecosystems in the Netherlands. Soon after a first version of our sketch map was published by a Dutch professional journal, copies appeared in policy documents, and also in a commercial and popular atlas of the Netherlands. Moreover, the map led to a question in the Dutch parliament about the sustainability of bog reserves under the future climate. Apparently, there was an urgent need for the information provided by the map. The map shows that climate change will presumably have the largest influence on ecosystems in the Netherlands that depend on precipitation as the major water source, like heathlands, dry grasslands, rain-fed moorland pools and raised bogs. Also highly susceptible are fens in reserves surrounded by deeply drained polders, because such fens depend on the inlet of surface water, of which quality is likely to deteriorate upon climate change. While the map is indicative for directions of change, in view of the uncertainties of our study, no conclusions should be drawn that may have far-reaching consequences, such as giving up certain nature targets that might no longer be feasible in the future climate. Instead, we advise to anticipate the potential threats from climate change by taking a number of adaptation measures that enhance the robustness of nature reserves. To improve climate change projections on hydrology and ecosystems, future research should especially focus on feedbacks of vegetation on the water balance, on processes that directly influence plant performance and on the ecological effects of weather extremes.

Regional uplift episodes along the NE Atlantic margin constrained by stratigraphic and thermochronologic data

NASA Astrophysics Data System (ADS)

Holford, S. P.; Green, P. F.; Hillis, R. R.; Duddy, I. R.; Turner, J. P.; Stoker, M. S.

2008-12-01

The magma-rich NE Atlantic passive margin provides a superb natural laboratory for studying vertical motions associated with continental rifting and the rift-drift transition. Here we present an extensive apatite fission-track analysis (AFTA) database from the British Isles which we combine with a detailed stratigraphic framework for the Cretaceous-Cenozoic sedimentary record of the NE Atlantic margin to constrain the uplift history along and inboard of this margin during the past 120 Myr. We show that the British Isles experienced a series of uplift episodes which began between 120 and 115 Ma, 65 and 55 Ma, 40 and 25 Ma and 20 and 15 Ma, respectively. Each episode is of regional extent (~100,000 sq km) and represents a major period of exhumation involving removal of up to 1 km or more of section. These uplift episodes can be correlated with a number of major tectonic unconformities recognised within the sedimentary succession of the NE Atlantic margin, suggesting that the margin was also affected by these uplift episodes. Anomalous syn- and post-rift uplift along this margin have been interpreted in terms of permanent and/or transient movements controlled by the Iceland plume, but neither the timing nor distribution of the uplift episodes, with the exception of the 65 to 55 Ma episode, supports a first-order control by plume activity on vertical motions. Each uplift episode correlates closely with key deformation events at adjacent plate boundaries, suggesting a causative link, and we examine the ways in which plate boundary forces can account for the observed uplift episodes. Similar km-scale uplift events are revealed by thermochronological studies in other magma-rich and magma-poor continental margins, e.g. SE Australia, South Africa, Brazil. The low angle unconformities which result from these regional episodes of km-scale burial and subsequent uplift are often incorrectly interpreted as representing periods of non-deposition and tectonic stability. Similar considerations have also led to an erroneous view of the post-rift stability of many continental margins. Our results indicate that km-scale regional uplift has affected many regions previously interpreted as areas of long-term stability, and that plate boundary deformation exerts the primary control on such episodes.

Coastal uplift west of Algiers (Algeria): pre- and post-Messinian sequences of marine terraces and rasas and their associated drainage pattern

NASA Astrophysics Data System (ADS)

Authemayou, Christine; Pedoja, Kevin; Heddar, Aicha; Molliex, Stéphane; Boudiaf, Azzedine; Ghaleb, Bassam; Van Vliet Lanoe, Brigitte; Delcaillau, Bernard; Djellit, Hamou; Yelles, Karim; Nexer, Maelle

2017-01-01

The North Africa passive margin is affected by the ongoing convergence between the African and Eurasian plates. This convergence is responsible for coastal uplift, folding, and reverse faulting on new and reactivated faults on the margin. The active deformation is diffuse and thus rather difficult to locate precisely. We aim to determine how a coastal landscape evolve in this geodynamic setting and gain insights into active tectonics. More particularly, we evidence and quantify coastal uplift pattern of the Chenoua, Sahel, and Algiers reliefs (Algeria), using sequences of marine terraces and rasas and computing several morphometric indices from the drainage pattern. Upper and Middle Pleistocene uplift rates are obtained by fossil shoreline mapping and preliminary U/Th dating of associated coastal deposits. Extrapolation of these rates combined to analyses of sea-level referential data and spatial relationships between marine terraces/rasas and other geological markers lead us to tentatively propose an age for the highest coastal indicators (purported the oldest). Values of morphometric indices showing correlations with uplift rate allow us to analyze uplift variation on area devoid of coastal sequence. Geological and geomorphological data suggest that coastal uplift probably occurred since the Middle Miocene. It resulted in the emergence of the Algiers massif, followed by the Sahel ridge massif. The Sahel ridge has asymmetrically grown by folding from west to east and was affected by temporal variation of uplift. Compared to previous study, the location of the Sahel fold axis has been shifted offshore, near the coast. The Chenoua fault vertical motion does not offset significantly the coastal sequence. Mean apparent uplift rates and corrected uplift rates since 120 ka are globally steady all along the coast with a mean value of 0.055 ± 0.015 mm/year (apparent) and of 0.005 ± 0.045 mm/year (corrected for eustasy). Mean apparent coastal uplift rates between 120 and 400 ka increase eastward from 0.045 ± 0.025 to 0.19 ± 0.12 mm/year (without correction for eustasy) or from 0.06 ± 0.06 to 0.2 ± 0.15 mm/year (with correction for eustasy). In addition, the combination of structural and geomorphic data suggests a low uplift rate for the southern part of the Algiers massif.

Mode and mechanisms of plateau uplifts

NASA Technical Reports Server (NTRS)

Mcgetchin, T. R.; Burke, K. C.; Thompson, G. A.; Young, R. A.

1980-01-01

The mode and mechanisms of plateau uplifts are reported, based on discussions which occurred as part of a conference on plateau uplifts sponsored by the Inter-Union Commission on Geodynamics and the Lunar and Planetary Institute. Major plateaus and high plains of the world are discussed with emphasis on the Colorado Plateau, which possesses a shield-like crust 45 km thick and occupies most of eastern Utah and parts of Colorado, Arizona, and New Mexico. Several uplift mechanisms are described, including thermal expansion due to a deep mantle plume or hot spot, and hydration reactions such as serpentinization. It is concluded that uplifts are most commonly associated with either subduction and its direct effects, or deep-seated thermal disturbances.

Emergence and evolution of Santa Maria Island (Azores)—The conundrum of uplifted islands revisited

USGS Publications Warehouse

Ramalho, Ricardo; Helffrich, George; Madeira, Jose; Cosca, Michael A.; Thomas, Christine; Quartau, Rui; Hipolito, Ana; Rovere, Alessio; Hearty, Paul; Avila, Sergio

2017-01-01

The growth and decay of ocean-island volcanoes are intrinsically linked to vertical movements. While the causes for subsidence are better understood, uplift mechanisms remain enigmatic. Santa Maria Island in the Azores Archipelago is an ocean-island volcano resting on top of young lithosphere, barely 480 km away from the Mid-Atlantic Ridge. Like most other Azorean islands, Santa Maria should be experiencing subsidence. Yet, several features indicate an uplift trend instead. In this paper, we reconstruct the evolutionary history of Santa Maria with respect to the timing and magnitude of its vertical movements, using detailed field work and 40Ar/39Ar geochronology. Our investigations revealed a complex evolutionary history spanning ∼6 m.y., with subsidence up to ca. 3.5 Ma followed by uplift extending to the present day. The fact that an island located in young lithosphere experienced a pronounced uplift trend is remarkable and raises important questions concerning possible uplift mechanisms. Localized uplift in response to the tectonic regime affecting the southeastern tip of the Azores Plateau is unlikely, since the area is under transtension. Our analysis shows that the only viable mechanism able to explain the uplift is crustal thickening by basal intrusions, suggesting that intrusive processes play a significant role even on islands standing on young lithosphere, such as in the Azores.

Investigating uplift in the South-Western Barents Sea using sonic and density well log measurements

NASA Astrophysics Data System (ADS)

Yang, Y.; Ellis, M.

2014-12-01

Sediments in the Barents Sea have undergone large amounts of uplift due to Plio-Pleistoncene deglaciation as well as Palaeocene-Eocene Atlantic rifting. Uplift affects the reservoir quality, seal capacity and fluid migration. Therefore, it is important to gain reliable uplift estimates in order to evaluate the petroleum prospectivity properly. To this end, a number of quantification methods have been proposed, such as Apatite Fission Track Analysis (AFTA), and integration of seismic surveys with well log data. AFTA usually provides accurate uplift estimates, but the data is limited due to its high cost. While the seismic survey can provide good uplift estimate when well data is available for calibration, the uncertainty can be large in areas where there is little to no well data. We estimated South-Western Barents Sea uplift based on well data from the Norwegian Petroleum Directorate. Primary assumptions include time-irreversible shale compaction trends and a universal normal compaction trend for a specified formation. Sonic and density logs from two Cenozoic shale formation intervals, Kolmule and Kolje, were used for the study. For each formation, we studied logs of all released wells, and established exponential normal compaction trends based on a single well. That well was then deemed the reference well, and relative uplift can be calculated at other well locations based on the offset from the normal compaction trend. We found that the amount of uplift increases along the SW to NE direction, with a maximum difference of 1,447 m from the Kolje FM estimate, and 699 m from the Kolmule FM estimate. The average standard deviation of the estimated uplift is 130 m for the Kolje FM, and 160 m for the Kolmule FM using the density log. While results from density logs and sonic logs have good agreement in general, the density log provides slightly better results in terms of higher consistency and lower standard deviation. Our results agree with published papers qualitatively with some differences in the actual amount of uplifts. The results are considered to be more accurate due to the higher resolution of the log scale data that was used.

Temporal variability of methane fluxes in West Siberian taiga bogs and its implications for estimating regional methane emission

NASA Astrophysics Data System (ADS)

Sabrekov, Alexander; Ilyasov, Danil; Terentieva, Irina; Glagolev, Mikhail; Maksyutov, Shamil

2017-04-01

The West Siberia Lowland (WSL) is the biggest peatland area in Eurasia and is situated in the high latitudes experiencing enhanced rate of climate change. During 2015-16 summer periods, seasonal measurements of methane emission were made at the field station «Mukhrino» in the WSL middle taiga zone. The study was made at 3 wetland ecosystem types covering 80% of the taiga wetland area: i) waterlogged hollows or depressed areas with water level above the moss surface, ii) oligotrophic hollows or depressed parts of bogs with water level beneath the moss surface, iii) forested bogs with dwarf shrubs-sphagnum vegetation. Seven series of measurements were made by a static chamber method in 2016 and four series - in 2015. In 2015, we observed non-typical weather conditions including early dry spring and short cold rainy summer. Oppositely, weather conditions in 2016 were closer to average long-term with warmer drier summer. Significant difference between these years allowed analyzing the temporal variability and its sources. Average methane flux rates from forested bogs were 0.57 mgCH4/m2/h in 2016 and 0.33 mgCH4/m2/h in 2015. Seasonal dynamic during both years had similar concave downward shape. The highest fluxes were observed in June and were corresponded to the highest WTL, the main limiting factor of emission from forested bogs. The lowest fluxes in July were related to the low WTL combining with the highest temperature of upper methanotrophy layer. Average methane flux rates from oligotrophic hollows were 7.18 mgCH4/m2/h in 2016 and 4.28 mgCH4/m2/h in 2015. Seasonal dynamic of methane emission was indistinct in 2015. On the contrary, in 2016 it had regular seasonal pattern with peak emissions in July, which were four times higher than in 2015. WTL was not the limiting factor for CH4 emission from oligotrophic hollows, because even in the driest ones it was only 10 cm below the surface. Thus, the difference between peak emissions in 2015 and 2016 was mainly related to the temperature, which was considerably higher in 2016. Average methane flux rates from waterlogged hollows were 2.19 mgCH4/m2/h in 2016 and 4.07 mgCH4/m2/h in 2015. Seasonal dynamic had prominent shape in both years, however, peak emissions were observed in different months. Overall, patterns of emission in these ecosystems had more complicate nature and needs future investigations. Regional methane emission was estimated using new wetland map by Terentieva et al. (2016). Seasonal dynamic data for 2015-16 years gave the regional flux of 161 and 1257 ktCH4/yr for forested bogs and oligotrophic hollows, respectively. Similar values were obtained using not seasonal dynamic but only flux medians for 2015-16 years. However, the usage of old dataset gave only 32 and 841 ktCH4/yr for forested bogs and oligotrophic hollows, respectively. Thus, seasonal dynamics data had lower impact on regional methane emission estimate comparing to interannual variability data. Terentieva, I.E., Glagolev, M.V., Lapshina, E.D., Sabrekov, A.F., Maksyutov, S. Mapping of West Siberian taiga wetland complexes using Landsat imagery: implications for methane emissions // Biogeosciences. 2016. V. 13. № 16. P. 4615-4626.

Uplift Patterns in the Forearc of the Middle America Trench, Costa Rica: Implications for Mass Balance and Fore-arc Kinematics

NASA Astrophysics Data System (ADS)

Fisher, D. M.; Gardner, T. W.; Sak, P.; Marshall, J. S.; Protti, M.

2001-12-01

Uplift patterns along the Pacific Coast of Costa Rica provide insight into the balance of mass in the fore arc and depict an inner forearc that thickens nonuniformly at the expense of a subsiding margin wedge. Offshore, incoming seamounts and ridges on the subducting Cocos plate result in embayment of the trench axis and scarring that reflects downdropping of fault bounded blocks in the wake of subducting seamounts. The upper slope displays a regional unconformity that records late Tertiary subsidence and arcward displacement of the trench axis. Uplifted marine wavecut benches along the coast of Costa Rica, combined with analysis of fault populations, indicate that the inner fore arc has experienced a history that is in marked contrast to the subsidence and erosion observed in the margin wedge. Regionally, the inner forearc, from Osa to Nicaragua, has experienced uplift. One way to produce this regional uplift signal is movement on an out-of-sequence fault, or an active fault arcward of the frontal thrust. The longitudinal fault that marks the front of the Fila Costena may be an example of such a fault. Wood from a raised wavecut platform along this thrust front was radiocarbon dated at 5540 yrs. A balanced cross section of the Fila Costena indicates a detachment at a depth of ~ 2 km near the contact between upper slope sediments of the Terraba basin and the underlying basement of the margin wedge. This cross section also requires a >10 km of shortening accomplished by underthrusting of the outer fore arc. Crustal thickening by this mechanism could explain the dichotomy between uplift of the mountainous Fila Costena and Talamanca Ranges and subsidence of the slope apron offshore. Superimposed on this regional uplift of the Costa Rican coast is a pattern of faster uplift within fault-bounded blocks that lie inboard of incoming seamount chains. Offshore of Nicoya, the subducting plate displays two parallel ridges: a ridge coincident with the trace of the Coc-Naz- East Pacific Rise junction and a ridge defined by the Fisher Seamount chain. Inboard of both these bathymetric features there are raised wavecut benches and headlands that expose Tertiary upper slope sediments. Radiocarbon dates for these platforms indicate maximum uplift rates of ~ 6 mm yr-1 with slower uplift rates between these regions. The largest scar in the Costa Rican forearc is a trough oriented parallel to the Car-Coc relative plate motion vector that extends from the trench to near the coastline. Inboard of this scar is the Herradura block, a block that has experienceed more uplift than adjacent regions. A wavecut platform near the faulted margin of the Herradura block yields radiocarbon dates of 1010-1650 yrs and uplift rates of ~2.5 mm yr-1. The Osa Peninsula inboard of the Cocos Ridge records some of the fastest uplift rates measured in the Costa Rican fore arc based on marine sediments deposited around the margins of this peninsula and radiocarbon (AMS)-dated as 27000 to 49000 yrs. The most striking aspect of uplift patterns is that the local areas of fastest uplift in the forearc lie inboard of the areas with the most scarring and erosion in the margin wedge offshore. This pattern of uplift requires either underplating of seamounts beneath the inner forearc or enhanced shortening and crustal thickening inboard of subducting seamounts.

Three Novel Herpesviruses of Endangered Clemmys and Glyptemys Turtles

PubMed Central

Ossiboff, Robert J.; Raphael, Bonnie L.; Ammazzalorso, Alyssa D.; Seimon, Tracie A.; Newton, Alisa L.; Chang, Tylis Y.; Zarate, Brian; Whitlock, Alison L.; McAloose, Denise

2015-01-01

The rich diversity of the world’s reptiles is at risk due to significant population declines of broad taxonomic and geographic scope. Significant factors attributed to these declines include habitat loss, pollution, unsustainable collection and infectious disease. To investigate the presence and significance of a potential pathogen on populations of critically endangered bog turtles (Glyptemys muhlenbergii) as well sympatric endangered wood (G. insculpta) and endangered spotted (Clemmys guttata) turtles in the northeastern United States, choanal and cloacal swabs collected from 230 turtles from 19 sites in 5 states were screened for herpesvirus by polymerase chain reaction. We found a high incidence of herpesvirus infection in bog turtles (51.5%; 105/204) and smaller numbers of positive wood (5) and spotted (1) turtles. Sequence and phylogenetic analysis revealed three previously uncharacterized alphaherpesviruses. Glyptemys herpesvirus 1 was the predominant herpesvirus detected and was found exclusively in bog turtles in all states sampled. Glyptemys herpesvirus 2 was found only in wood turtles. Emydid herpesvirus 2 was found in a small number of bog turtles and a single spotted turtle from one state. Based on these findings, Glyptemys herpesvirus 1 appears to be a common infection in the study population, whereas Glyptemys herpesvirus 2 and Emydid herpesvirus 2 were not as frequently detected. Emydid herpesvirus 2 was the only virus detected in more than one species. Herpesviruses are most often associated with subclinical or mild infections in their natural hosts, and no sampled turtles showed overt signs of disease at sampling. However, infection of host-adapted viruses in closely related species can result in significant disease. The pathogenic potential of these viruses, particularly Emydid herpesvirus 2, in sympatric chelonians warrants additional study in order to better understand the relationship of these viruses with their endangered hosts. PMID:25875510

Three novel herpesviruses of endangered Clemmys and Glyptemys turtles.

PubMed

Ossiboff, Robert J; Raphael, Bonnie L; Ammazzalorso, Alyssa D; Seimon, Tracie A; Newton, Alisa L; Chang, Tylis Y; Zarate, Brian; Whitlock, Alison L; McAloose, Denise

2015-01-01

The rich diversity of the world's reptiles is at risk due to significant population declines of broad taxonomic and geographic scope. Significant factors attributed to these declines include habitat loss, pollution, unsustainable collection and infectious disease. To investigate the presence and significance of a potential pathogen on populations of critically endangered bog turtles (Glyptemys muhlenbergii) as well sympatric endangered wood (G. insculpta) and endangered spotted (Clemmys guttata) turtles in the northeastern United States, choanal and cloacal swabs collected from 230 turtles from 19 sites in 5 states were screened for herpesvirus by polymerase chain reaction. We found a high incidence of herpesvirus infection in bog turtles (51.5%; 105/204) and smaller numbers of positive wood (5) and spotted (1) turtles. Sequence and phylogenetic analysis revealed three previously uncharacterized alphaherpesviruses. Glyptemys herpesvirus 1 was the predominant herpesvirus detected and was found exclusively in bog turtles in all states sampled. Glyptemys herpesvirus 2 was found only in wood turtles. Emydid herpesvirus 2 was found in a small number of bog turtles and a single spotted turtle from one state. Based on these findings, Glyptemys herpesvirus 1 appears to be a common infection in the study population, whereas Glyptemys herpesvirus 2 and Emydid herpesvirus 2 were not as frequently detected. Emydid herpesvirus 2 was the only virus detected in more than one species. Herpesviruses are most often associated with subclinical or mild infections in their natural hosts, and no sampled turtles showed overt signs of disease at sampling. However, infection of host-adapted viruses in closely related species can result in significant disease. The pathogenic potential of these viruses, particularly Emydid herpesvirus 2, in sympatric chelonians warrants additional study in order to better understand the relationship of these viruses with their endangered hosts.

Ecophysiological adaptations of anaerobic bacteria to low pH: analysis of anaerobic digestion in acidic bog sediments. [Lactobacillus; Clostridium; Sarcina ventriculi

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

Goodwin, S.; Zeikus, G.J.

1987-01-01

The dynamics of anaerobic digestion were examined in the low-pH sediments of Crystal Bog in Wisconsin. The sediments (pH 4.9) contained 71% organic matter and the following concentrations of dissolved gases (micromoles per liter):CO/sub 2/, 1140; CH/sub 4/, 490; and H/sub 2/, 0.01. The rate of methane production was 6.2 ..mu..mol/liter of sediment per h, which is slower than eutrophic, neutral sediments. Microbial metabolic processes displayed the following pH optima: hydrolysis reactions, between 4.2 and 5.6; aceticlastic methanogenesis, 5.2; and hydrogen-consuming reactions, 5.6. The turnover rate constants for key intermediary metabolites were (h/sup -1/): glucose, 1.10; lactate, 0.277; acetate, 0.118;more » and ethanol, 0.089. The populations of anaerobes were low, with hydrolytic groups (10/sup 6//ml) several orders of magnitude higher than methanogens (10/sup 2//ml). The addition of carbon electron donors to the sediment resulted in the accumulation of hydrogen, whereas the addition of hydrogen resulted in the accumulation of fatty acids and the inhibition of hydrogen-producing acetogenic reactions. Strains of Lactobacillus, Clostridium, and Sarcina ventriculi were isolated from the bog, and their physiological attributes were characterized in relation to hydrolytic process functions in the sediments. The present studies provide evidence that the pH present in the bog sediments alter anaerobic digestion processes s, that total biocatalytic activity is lower bu the general carbon and electron flow pathways are similar to those of neutral anoxic sediments.« less

2000 Years of Grazing History and the Making of the Cretan Mountain Landscape, Greece.

PubMed

Jouffroy-Bapicot, Isabelle; Vannière, Boris; Iglesias, Virginia; Debret, Maxime; Delarras, Jean-François

2016-01-01

Understanding the processes that led to the recent evolution of Mediterranean landscapes is a challenging question that can be addressed with paleoecological data. Located in the White Mountains of Crete, Asi Gonia peat bog constitutes an exceptional 2000-years-long sedimentary archive of environmental change. In this study, we document the making of the White Mountains landscape and assess human impact on ecosystem trajectories. The paleoenvironmental reconstruction is based on high-resolution analyses of sediment, pollen, dung fungal spores and charcoal obtained from a 6-m core collected from the bog. Multiproxy analyses and a robust chronological control have shed light on anthropogenic and natural processes that have driven ecological changes, giving rise to the present-day Mediterranean ecosystem. Our results suggest that sediment accumulation began during the transition from the Hellenistic to the Roman period, likely due to watershed management. The evolution of the peat bog as well as vegetation dynamics in the surrounding area were linked to past climate changes but were driven by human activities, among which breeding was of great importance. Charcoal analysis reveals that fire was largely used for the construction and maintenance of sylvo-agropastoral areas. Pollen data allow the identification of three main vegetation assemblages: 1) evergreen oak forest (before ca. 850 AD), 2) heather maquis (ca. 850 to 1870 AD), 3) phrygana/steppe landscape. Rapid changes between phases in vegetation development are associated with tipping-points in ecosystem dynamics resulting from anthropogenic impact. The modern ecosystem did not get established until the 20th century, and it is characterized by biodiversity loss along with a dramatic drying of the peat bog.

2000 Years of Grazing History and the Making of the Cretan Mountain Landscape, Greece

PubMed Central

Jouffroy-Bapicot, Isabelle; Vannière, Boris; Iglesias, Virginia; Debret, Maxime; Delarras, Jean-François

2016-01-01

Understanding the processes that led to the recent evolution of Mediterranean landscapes is a challenging question that can be addressed with paleoecological data. Located in the White Mountains of Crete, Asi Gonia peat bog constitutes an exceptional 2000-years-long sedimentary archive of environmental change. In this study, we document the making of the White Mountains landscape and assess human impact on ecosystem trajectories. The paleoenvironmental reconstruction is based on high-resolution analyses of sediment, pollen, dung fungal spores and charcoal obtained from a 6-m core collected from the bog. Multiproxy analyses and a robust chronological control have shed light on anthropogenic and natural processes that have driven ecological changes, giving rise to the present-day Mediterranean ecosystem. Our results suggest that sediment accumulation began during the transition from the Hellenistic to the Roman period, likely due to watershed management. The evolution of the peat bog as well as vegetation dynamics in the surrounding area were linked to past climate changes but were driven by human activities, among which breeding was of great importance. Charcoal analysis reveals that fire was largely used for the construction and maintenance of sylvo-agropastoral areas. Pollen data allow the identification of three main vegetation assemblages: 1) evergreen oak forest (before ca. 850 AD), 2) heather maquis (ca. 850 to 1870 AD), 3) phrygana/steppe landscape. Rapid changes between phases in vegetation development are associated with tipping-points in ecosystem dynamics resulting from anthropogenic impact. The modern ecosystem did not get established until the 20th century, and it is characterized by biodiversity loss along with a dramatic drying of the peat bog. PMID:27280287

Demographic and genetic status of an isolated population of bog turtles (Glyptemys muhlenbergii): Implications for managing small populations of long-lived animals

USGS Publications Warehouse

Pittman, Shannon E.; King, T.L.; Faurby, S.; Dorcas, M.E.

2011-01-01

In this study, we sought to determine the population stability and genetic diversity of one isolated population of the federally-threatened bog turtle (Glyptemys muhlenbergii) in North Carolina. Using capture-recapture data, we estimated adult survival and population growth rate from 1992 to 2007. We found that the population decreased from an estimated 36 adult turtles in 1994 to approximately 11 adult turtles in 2007. We found a constant adult survival of 0. 893 (SE = 0. 018, 95% confidence interval, 0. 853-0. 924) between 1992 and 2007. Using 18 microsatellite markers, we compared the genetic status of this population with five other bog turtle populations. The target population displayed allelic richness (4. 8 ?? 0. 5) and observed heterozygosity (0. 619 ?? 0. 064) within the range of the other bog turtle populations. Coalescent analysis of population growth rate, effective population size, and timing of population structuring event also indicated the genetics of the target population were comparable to the other populations studied. Estimates of effective population size were a proportion of the census size in all populations except the target population, in which the effective population size was larger than the census size (30 turtles vs. 11 turtles). We attribute the high genetic diversity in the target population to the presence of multiple generations of old turtles. This study illustrates that the demographic status of populations of long-lived species may not be reflected genetically if a decline occurred recently. Consequently, the genetic integrity of populations of long-lived animals experiencing rapid demographic bottlenecks may be preserved through conservation efforts effective in addressing demographic problems. ?? 2011 Springer Science+Business Media B.V.

Control of paleoshorelines by trench forebulge uplift, Loyalty Islands

NASA Astrophysics Data System (ADS)

Dickinson, William R.

2013-07-01

Unlike most tropical Pacific islands, which lie along island arcs or hotspot chains, the Loyalty Islands between New Caledonia and Vanuatu owe their existence and morphology to the uplift of pre-existing atolls on the flexural forebulge of the New Hebrides Trench. The configuration and topography of each island is a function of distance from the crest of the uplifted forebulge. Both Maré and Lifou are fully emergent paleoatolls upon which ancient barrier reefs form highstanding annular ridges that enclose interior plateaus representing paleolagoon floors, whereas the partially emergent Ouvea paleoatoll rim flanks a drowned remnant lagoon. Emergent paleoshoreline features exposed by island uplift include paleoreef flats constructed as ancient fringing reefs built to past low tide levels and emergent tidal notches incised at past high tide levels. Present paleoshoreline elevations record uplift rates of the islands since last-interglacial and mid-Holocene highstands in global and regional sea levels, respectively, and paleoreef stratigraphy reflects net Quaternary island emergence. The empirical uplift rates vary in harmony with theoretical uplift rates inferred from the different positions of the islands in transit across the trench forebulge at the trench subduction rate. The Loyalty Islands provide a case study of island environments controlled primarily by neotectonics.

Ecology of testate amoebae in an Amazonian peatland and development of a transfer function for palaeohydrological reconstruction.

PubMed

Swindles, Graeme T; Reczuga, Monika; Lamentowicz, Mariusz; Raby, Cassandra L; Turner, T Edward; Charman, Dan J; Gallego-Sala, Angela; Valderrama, Elvis; Williams, Christopher; Draper, Frederick; Honorio Coronado, Euridice N; Roucoux, Katherine H; Baker, Tim; Mullan, Donal J

2014-08-01

Tropical peatlands represent globally important carbon sinks with a unique biodiversity and are currently threatened by climate change and human activities. It is now imperative that proxy methods are developed to understand the ecohydrological dynamics of these systems and for testing peatland development models. Testate amoebae have been used as environmental indicators in ecological and palaeoecological studies of peatlands, primarily in ombrotrophic Sphagnum-dominated peatlands in the mid- and high-latitudes. We present the first ecological analysis of testate amoebae in a tropical peatland, a nutrient-poor domed bog in western (Peruvian) Amazonia. Litter samples were collected from different hydrological microforms (hummock to pool) along a transect from the edge to the interior of the peatland. We recorded 47 taxa from 21 genera. The most common taxa are Cryptodifflugia oviformis, Euglypha rotunda type, Phryganella acropodia, Pseudodifflugia fulva type and Trinema lineare. One species found only in the southern hemisphere, Argynnia spicata, is present. Arcella spp., Centropyxis aculeata and Lesqueresia spiralis are indicators of pools containing standing water. Canonical correspondence analysis and non-metric multidimensional scaling illustrate that water table depth is a significant control on the distribution of testate amoebae, similar to the results from mid- and high-latitude peatlands. A transfer function model for water table based on weighted averaging partial least-squares (WAPLS) regression is presented and performs well under cross-validation (r(2)(apparent)= 0.76, RMSE = 4.29; r(2)(jack)= 0.68, RMSEP =5.18). The transfer function was applied to a 1-m peat core, and sample-specific reconstruction errors were generated using bootstrapping. The reconstruction generally suggests near-surface water tables over the last 3,000 years, with a shift to drier conditions at c. cal. 1218-1273 AD.

Late Miocene uplift in the Romagnan Apennines and the detachment of subducted lithosphere

NASA Astrophysics Data System (ADS)

van der Meulen, M. J.; Kouwenhoven, T. J.; van der Zwaan, G. J.; Meulenkamp, J. E.; Wortel, M. J. R.

1999-12-01

We report part of a test of the hypothesis that detachment of subducted lithosphere may be a process of lateral propagation of a horizontal tear [Wortel and Spakman, Proc. Kon. Ned. Akad. Wetensch., 95 (1992) 325-347]. We have used the Apennines as a test area. The test procedure consists of the comparison of hypothetical vertical motions, predicted from the expected redistribution of slab pull forces, with observed vertical motions. We demonstrate that a Late Miocene depocentre migration from the Northern towards the Central Apennines is associated with uplift of (the fore-arc of) the Northern Apennines. Such a combination of a depocentre shift and uplift is thought to be diagnostic for lateral migration of slab detachment. The depocentre migration was identified in earlier work [van der Meulen et al., Earth Planet. Sci. Lett., 154 (1998) 203-219]. This contribution focuses on uplift, which has primarily been identified through the geohistory analysis of the Monte del Casino Section (Romagnan Apennines, Northern Italy). Owing to methodological problems, the start and duration of the uplift phase could not be constrained, and only a minimum estimate of the total amount of uplift (483±180 m) is obtained. The data do allow for an estimate of the uplift rate: 163±61 cm/ky. A review of regional data results in better constraints on the timing of the above lateral reorganisation of the fore-arc, and on the spatial extent of the uplifted area. Depocentre development in the Central Apennines began between 8.6 and 8.3 Ma B.P. Uplift started between 9 and 8 Ma B.P., and affected the entire northernmost Apennines.

A Literature Survey and Experimental Evaluation of the State-of-the-Art in Uplift Modeling: A Stepping Stone Toward the Development of Prescriptive Analytics.

PubMed

Devriendt, Floris; Moldovan, Darie; Verbeke, Wouter

2018-03-01

Prescriptive analytics extends on predictive analytics by allowing to estimate an outcome in function of control variables, allowing as such to establish the required level of control variables for realizing a desired outcome. Uplift modeling is at the heart of prescriptive analytics and aims at estimating the net difference in an outcome resulting from a specific action or treatment that is applied. In this article, a structured and detailed literature survey on uplift modeling is provided by identifying and contrasting various groups of approaches. In addition, evaluation metrics for assessing the performance of uplift models are reviewed. An experimental evaluation on four real-world data sets provides further insight into their use. Uplift random forests are found to be consistently among the best performing techniques in terms of the Qini and Gini measures, although considerable variability in performance across the various data sets of the experiments is observed. In addition, uplift models are frequently observed to be unstable and display a strong variability in terms of performance across different folds in the cross-validation experimental setup. This potentially threatens their actual use for business applications. Moreover, it is found that the available evaluation metrics do not provide an intuitively understandable indication of the actual use and performance of a model. Specifically, existing evaluation metrics do not facilitate a comparison of uplift models and predictive models and evaluate performance either at an arbitrary cutoff or over the full spectrum of potential cutoffs. In conclusion, we highlight the instability of uplift models and the need for an application-oriented approach to assess uplift models as prime topics for further research.

Uplifting Leadership

ERIC Educational Resources Information Center

Hargreaves, Andy; Boyle, Alan

2015-01-01

To find out how organizations turn failure into success, Andrew Hargreaves and his colleagues studied more than 15 business, sports, and education organizations. They found that the secret to these organizations' success came down to just two words: uplifting leadership. Uplifting leadership, write Hargreaves and Boyle in this article, raises the…

Rise of the central Andean coast by earthquakes straddling the Moho

NASA Astrophysics Data System (ADS)

Melnick, Daniel

2016-05-01

Surface movements during the largest subduction zone earthquakes commonly drown coastlines. Yet, on geological timescales, coastlines above subduction zones uplift. Here I use a morphometric analysis combined with a numerical model of landscape evolution to estimate uplift rates along the central Andean rasa--a low-relief coastal surface bounded by a steep cliff formed by wave erosion. I find that the rasa has experienced steady uplift of 0.13 +/- 0.04 mm per year along a stretch of more than 2,000 km in length, during the Quaternary. These long-term uplift rates do not correlate with Global Positioning System (GPS) measurements of interseismic movements over the decadal scale, which implies that permanent uplift is not predominantly accumulated during the interseismic period. Instead, the rate of rasa uplift correlates with slip during earthquakes straddling the crust-mantle transition, the Moho. Such deeper earthquakes with magnitude 7 to 8 that occurred between 1995 and 2012 resulted in decimetres of coastal uplift. Slip during these earthquakes is located below the locked portion of the plate interface, and therefore may translate into permanent deformation of the overlying plate, where it causes uplift of the coastline. Thus, lower parts of the plate boundary are stably segmented over hundreds to millions of years. I suggest the coastline marks the surface expression of the transition between the shallow, locked seismogenic domain and the deeper, conditionally stable domain where modest earthquakes build up topography.

Upper Pleistocene uplifted shorelines as tracers of (local rather than global) subduction dynamics

NASA Astrophysics Data System (ADS)

Henry, Hadrien; Regard, Vincent; Pedoja, Kevin; Husson, Laurent; Martinod, Joseph; Witt, Cesar; Heuret, Arnauld

2014-08-01

Past studies have shown that high coastal uplift rates are restricted to active areas, especially in a subduction context. The origin of coastal uplift in subduction zones, however, has not yet been globally investigated. Quaternary shorelines correlated to the last interglacial maximum (MIS 5e) were defined as a global tectonic benchmark (Pedoja et al., 2011). In order to investigate the relationships between the vertical motion and the subduction dynamic parameters, we cross-linked this coastal uplift database with the “geodynamical” databases from Heuret (2005), Conrad and Husson (2009) and Müller et al. (2008). Our statistical study shows that: (1) the most intuitive parameters one can think responsible for coastal uplift (e.g., subduction obliquity, trench motion, oceanic crust age, interplate friction and force, convergence variation, dynamic topography, overriding and subducted plate velocity) are not related with the uplift (and its magnitude); (2) the only intuitive parameter is the distance to the trench which shows in specific areas a decrease from the trench up to a distance of ˜300 km; (3) the slab dip (especially the deep slab dip), the position along the trench and the overriding plate tectonic regime are correlated with the coastal uplift, probably reflecting transient changes in subduction parameters. Finally we conclude that the first order parameter explaining coastal uplift is small-scale heterogeneities of the subducting plate, as for instance subducting aseismic ridges. The influence of large-scale geodynamic setting of subduction zones is secondary.

Erosion and landscape development decouple strontium and sulfur in the transition to dominance by atmospheric inputs

USGS Publications Warehouse

Bern, C.R.; Porder, S.; Townsend, A.R.

2007-01-01

Weathering and leaching can progressively deplete the pools of soluble, rock-derived elements in soils and ecosystems over millennial time-scales, such that productivity increasingly relies on inputs from atmospheric deposition. This transition has been explored using strontium isotopes, which have been widely assumed to be a proxy for the provenance of other rock-derived elements. We compared rock versus atmospheric proportions of strontium to those for sulfur, a plant macronutrient, at several tropical forest sites in Hawaii and Costa Rica. Isotopic analyses reveal that sulfur is often decoupled from strontium in the transition to atmospheric dependence. Decoupling is likely the result of differences in chemical factors such as atmospheric input rates, mobility in the soil environment, and mineral weathering susceptibility. Strontium and sulfur decoupling appears to be accentuated by the physical process of erosion. Erosion rates are presumed to be high on the Osa Peninsula of Costa Rica, where the recent onset of rapid tectonic uplift has placed the landscape in a transient state. Decoupling is strong there, as erosion has rejuvenated the supply of rock-derived strontium but not sulfur. The landscape response to changes in tectonic uplift on the Osa Peninsula has produced decoupling at the landscape scale. Decoupling is more variable along a Hawaiian catena, presumably due to smaller scale variations in erosion rates and their influence on rejuvenation of rock-strontium inputs. These results illustrate how chemical and physical processes can interact to produce contrasting origins for different nutrient elements in soils and the ecosystems they support. ?? 2007 Elsevier B.V. All rights reserved.

Ultrafast holographic technique for 3D in situ documentation of cultural heritage

NASA Astrophysics Data System (ADS)

Frey, Susanne; Bongartz, Jens; Giel, Dominik M.; Thelen, Andrea; Hering, Peter

2003-10-01

A novel 3d reconstruction method for medical application has been applied for the examination and documentation of a 2000-year-old bog body. An ultra-fast pulsed holographic camera has been modified to allow imaging of the bog body from different views. Full-scale daylight copies of the master holograms give a detailed impressive three-dimensional view of the mummy and can be exhibited instead of the object. In combination with a rapid prototyping model (built by the Rapid Prototyping group of the Stiftung caesar, Bonn, Germany) derived from computer tomography (CT) data our results are an ideal basis for a future facial reconstruction.

Intercomparison of radiocarbon bomb pulse and 210Pb age models. A study in a peat bog core from North Poland

NASA Astrophysics Data System (ADS)

Piotrowska, Natalia; De Vleeschouwer, François; Sikorski, Jarosław; Pawlyta, Jacek; Fagel, Nathalie; Le Roux, Gaël; Pazdur, Anna

2010-04-01

Radiocarbon and 210Pb were measured on the uppermost 40 cm of a Wardenaar peat core retrieved from a Baltic raised bog at Słowińskie Błota (Pomerania, North Poland). This site is the subject of ongoing multiproxy studies covering the last 1300 years. Radiocarbon age model was constructed on the basis of 14 AMS dates obtained on selected Sphagnum spp. fragments, with use of P_Sequence tool. We present here a comparison of this model with the age model obtained using CRS model classically applied to 210Pb measurements.

SPRUCE S1 Bog Sphagnum CO2 Flux Measurements and Partitioning into Re and GPP

DOE Data Explorer

Walker, A. P. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; Carter, K. R. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; Hanson, P. J. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; Nettles, W. R. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; Philips, J. R. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; Sebestyen, S. D. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; Weston, D. J. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.

2015-06-01

This data set provides (1) the results of in-situ Sphagnum-peat hourly net ecosystem exchange (NEE) measured using a LICOR 8100 gas exchange system and (2) the component fluxes -- gross primary production (GPP) and ecosystem respiration (Re), derived using empirical regressions.NEE measurements were made from 6 June to 6 November 2014 and 20 March to 10 May 2015. Three 8100 chambers per dominant species (S. magellanicum or S. fallax) were placed in the S1 Bog in relatively open ground where there was no obvious hummock-hollow microtopography. The 8100 chambers were not located in the SPRUCE experimental enclosures.

Net ecosystem exchange and energy fluxes measured with the eddy covariance technique in a western Siberian bog

NASA Astrophysics Data System (ADS)

Alekseychik, Pavel; Mammarella, Ivan; Karpov, Dmitry; Dengel, Sigrid; Terentieva, Irina; Sabrekov, Alexander; Glagolev, Mikhail; Lapshina, Elena

2017-08-01

Very few studies of ecosystem-atmosphere exchange involving eddy covariance data have been conducted in Siberia, with none in the western Siberian middle taiga. This work provides the first estimates of carbon dioxide (CO2) and energy budgets in a typical bog of the western Siberian middle taiga based on May-August measurements in 2015. The footprint of measured fluxes consisted of a homogeneous mixture of tree-covered ridges and hollows with the vegetation represented by typical sedges and shrubs. Generally, the surface exchange rates resembled those of pine-covered bogs elsewhere. The surface energy balance closure approached 100 %. Net CO2 uptake was comparatively high, summing up to 202 gC m-2 for the four measurement months, while the Bowen ratio was seasonally stable at 28 %. The ecosystem turned into a net CO2 source during several front passage events in June and July. The periods of heavy rain helped keep the water table at a sustainably high level, preventing a usual drawdown in summer. However, because of the cloudy and rainy weather, the observed fluxes might rather represent the special weather conditions of 2015 than their typical magnitudes.

Anomalous concentrations of zinc and copper in highmoor peat bog, southeast coast of Lake Baikal

NASA Astrophysics Data System (ADS)

Bobrov, V. A.; Bogush, A. A.; Leonova, G. A.; Krasnobaev, V. A.; Anoshin, G. N.

2011-08-01

When examining the peat deposit discovered in Vydrinaya bog, South Baikal region, the authors encountered anomalous Zn and Cu concentrations for highmoors being up to 600-500 ppm on a dry matter basis in the Early Holocene beds (360-440 cm) formed 11 000-8500 years ago. It has been demonstrated that Zn and Cu are present inside the plant cells of peat moss in the form of authigenic sulfide minerals of micron size. Apart from Zn and Cu, native Ag particles (5-7 um) have been encountered in the peat of the Vydrinaya bog at a depth of 390-410 cm; these particles formed inside the organic matter of the plasma membrane of peat moss containing Ca, Al, S, and Cu. This study suggests probable patterns of the formation of zinc sulfides, copper sulfides, and native silver in peat moss. The results obtained indicate that biogenic mineral formation plays a significant role in this system, which is a very important argument in the discussion on the ore genesis, in which physicochemical processes are normally favored, while the role of living matter is quite frequently disregarded.

Comparative Analysis of Phenolic Content and Profile, Antioxidant Capacity and Anti-inflammatory Bioactivity in Wild Alaskan and Commercial Vaccinium Berries

PubMed Central

Grace, Mary H.; Esposito, Debora; Dunlap, Kriya L.; Lila, Mary Ann

2014-01-01

Wild Alaskan Vaccinium berries, V. vitis-idaea (lowbush cranberry) and V. uliginosum (bog blueberry), were investigated in parallel to their commercial berry counterparts; V. macrocarpon (cranberry) and V. angustifolium (lowbush blueberry). Lowbush cranberry accumulated about twice the total phenolics (624.4 mg/100 g FW) and proanthocyanidins (278.8 mg/100 g) content as commercial cranberries, but A-type proanthocyanidins were more prevalent in the latter. Bog blueberry anthocyanin and total phenolic contents of 220 and 504.5 mg/100 g, respectively, significantly exceeded those of the lowbush blueberry. Chlorogenic acid, however, was quite high in lowbush blueberry (83.1 mg/100 g), but undetected in bog blueberry, and the proanthocyanidins of lowbush blueberry had significantly higher levels of polymerization. Antioxidant capacity (DPPH, APTS and FRAP) correlated with phenolic content for each berry. A polyphenol-rich fraction from lowbush cranberry exhibited dose-dependent inhibition of LPS-elicited induction of IL-1β in RAW 264.7 cells, indicative of strong anti-inflammatory activity. These results corroborate the historic use of wild Alaskan berries as medicinally-important foods in Alaska Native communities. PMID:24219831

Comparative analysis of phenolic content and profile, antioxidant capacity, and anti-inflammatory bioactivity in wild Alaskan and commercial Vaccinium berries.

PubMed

Grace, Mary H; Esposito, Debora; Dunlap, Kriya L; Lila, Mary Ann

2014-05-07

Wild Alaskan Vaccinium berries, V. vitis-idaea (lowbush cranberry) and V. uliginosum (bog blueberry), were investigated in parallel with their commercial berry counterparts, V. macrocarpon (cranberry) and V. angustifolium (lowbush blueberry). Lowbush cranberry accumulated about twice the total phenolics (624.4 mg/100 g FW) and proanthocyanidins (278.8 mg/100 g) content as commercial cranberries, but A-type proanthocyanidins were more prevalent in the latter. Bog blueberry anthocyanin and total phenolic contents of 220 and 504.5 mg/100 g, respectively, significantly exceeded those of the lowbush blueberry. Chlorogenic acid, however, was quite high in lowbush blueberry (83.1 mg/100 g), but undetected in bog blueberry, and the proanthocyanidins of lowbush blueberry had significantly higher levels of polymerization. Antioxidant capacity (DPPH, APTS, and FRAP) correlated with phenolic content for each berry. A polyphenol-rich fraction from lowbush cranberry exhibited dose-dependent inhibition of LPS-elicited induction of IL-1β in RAW 264.7 cells, indicative of strong anti-inflammatory activity. These results corroborate the historic use of wild Alaskan berries as medicinally important foods in Alaska Native communities.

Historical peat loss explains limited short-term response of drained blanket bogs to rewetting.

PubMed

Williamson, Jennifer; Rowe, Edwin; Reed, David; Ruffino, Lucia; Jones, Peter; Dolan, Rachel; Buckingham, Helen; Norris, David; Astbury, Shaun; Evans, Chris D

2017-03-01

This study assessed the short-term impacts of ditch blocking on water table depth and vegetation community structure in a historically drained blanket bog. A chronosequence approach was used to compare vegetation near ditches blocked 5 years, 4 years and 1 year prior to the study with vegetation near unblocked ditches. Plots adjacent to and 3 m away from 70 ditches within an area of blanket bog were assessed for floristic composition, aeration depth using steel bars, and topography using LiDAR data. No changes in aeration depth or vegetation parameters were detected as a function of ditch-blocking, time since blocking, or distance from the ditch, with the exception of non-Sphagnum bryophytes which had lower cover in quadrats adjacent to ditches that had been blocked for 5 years. Analysis of LiDAR data and the observed proximity of the water table to the peat surface led us to conclude that the subdued ecosystem responses to ditch-blocking were the result of historical peat subsidence within a 4-5 m zone either side of each ditch, which had effectively lowered the peat surface to the new, ditch-influenced water table. We estimate that this process led to the loss of around 500,000 m 3 peat within the 38 km 2 study area following drainage, due to a combination of oxidation and compaction. Assuming that 50% of the volume loss was due to oxidation, this amounts to a carbon loss of 11,000 Mg C over this area, i.e. 3 Mg C ha -1 . The apparent 'self-rewetting' of blanket bogs in the decades following drainage has implications for their restoration as it suggests that there may not be large quantities of dry peat left to rewet, and that there is a risk of inundation (potentially leading to high methane emissions) along subsided ditch lines. Many peatland processes are likely to be maintained in drained blanket bog, including support of typical peatland vegetation, but infilling of lost peat and recovery of original C stocks are likely to take longer than is generally anticipated. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.

GPR attenuation analyses using spectral ratios of primary and multiple arrivals: examples from Welsh peat bogs

NASA Astrophysics Data System (ADS)

Booth, A.; Carless, D.; Kulessa, B.

2014-12-01

Ground penetrating radar (GPR) is widely applied to qualitative and quantitative interpretation of near-surface targets. Surface deployments of GPR most widely characterise physical properties in terms of some measure of GPR wavelet velocity. Wavelet amplitude is less-often considered, potentially due to difficulties in measuring this quantity: amplitudes are distorted by the anisotropic radiation pattern of antennas, and the ringy GPR wavelet can make successive events difficult to isolate. However, amplitude loss attributes could provide a useful means of estimating the physical properties of a target. GPR energy loss is described by the bandwidth-limited quality factor Q* which, for low-loss media, is proportional to the ratio of dielectric permittivity, ɛ, and electrical conductivity, σ. Comparing the frequency content of two arrivals yields an estimate of interval Q*, but only if they are sufficiently distinct. There may be sufficient separation between a primary reflection and its long-path multiple (i.e. a 'repeat path' of the primary reflection) therefore a dataset that is rich in multiples may be suitable for robust Q* analysis. The Q* between a primary and multiple arrival describes all frequency-dependent loss mechanisms in the interval between the free-surface and the multiple-generating horizon: assuming that all reflectivity is frequency-independent, Q* can be used to estimate ɛ and/or σ. We measure Q* according to the spectral ratio method, for synthetic and real GPR datasets. Our simulations are performed using the finite-difference algorithm GprMax, and represent our example data of GPR acquisitions over peat bogs. These data are a series of 100 MHz GPR acquisitions over sites in the Brecon Beacons National Park of South Wales. The base of the bogs (the basal peat/mineral soil contact) is often a strong multiple-generating horizon. As an example, data from Waun Ddu bog show these events lagging by ~75 ns: GPR velocity is measured here at 0.034 m/ns (relative ɛ of 77.9) and spectral ratios suggest Q* of 19.9 [-6.6 +19.4]. This Q* implies that the bulk σ of the bog is 21.7 [-10.7 +10.8] mS/m. Our measurements require in situ verification (e.g. comparison with co-located electrical resistivity profiles) but our method provides a promising addition to the suite of GPR analysis tools.

Environmental and biogeochemical controls on N2 fixation in ombrotrophic peatlands

NASA Astrophysics Data System (ADS)

Zivkovic, T.; Moore, T. R.

2017-12-01

Northern peatlands have low atmospheric nitrogen (N) inputs and acquire N mostly via biological, microbially-driven N2-fixation. Little is known about rates and controls on N2-fixation in ombrotrophic bogs. We conducted two studies to test environmental and biogeochemical controls on N2-fixation. First, we used acetylene reduction assay (ARA) calibrated with 15N2 tracer to measure N2-fixation rates in three species of Sphagnum mosses along a hydrological gradient (beaver pond, hollow and hummock in bog margin and in bog) at Mer Bleue bog from June-October 2013 and May - November 2014. We tested the following controls: moisture availability, temperature, and PAR. The largest ARA rates throughout both seasons occurred in the pond in floating Sphagnum cuspidatum mats (50.3 ± 12.9 μmol m-2 d-1 Mean ± SE), which were up to 2.5 times larger than the rates found in the driest hummock site. There was a significant seasonal peak in both years in July and early August that coincided with the peak of the air temperature. In fact, 45% of the variance of N2 fixation rates over the two field seasons was explained by rain events, water table fluctuations and the surface peat temperature (multiple regression analysis, n = 539). Our results highlight the potential impact of climate change, namely negative effects due to potential droughts and positive effect of warming, on N2 fixation patterns in ombrotrophic peatlands. Secondly, we tested stoichiometric controls (Sphagnum tissue N and phosphorous (P) ratio) of N2-fixation. In a controlled environment, we selected eight study sites along a latitudinal gradient from temperate, boreal to subarctic zone in eastern Canada. We found that decreasing N:P ratio corresponded to increasing N2-fixation. N:P explained 65% of the variance in N2-fixation in hollows but only 20% in hummocks. Changes in neither N or P concentration alone explained the increase in N2-fixation better than N:P ratio. We interpret that the difference between hollows and hummocks results from the availability of moisture that further limits N2-fixation. When moisture is not a limiting factor, i.e. in hollows, N:P is the best predictor of N2-fixation in bogs.

Carbon Fluxes in Dissolved and Gaseous Forms for a Restored Peatland in British Columbia, Canada

NASA Astrophysics Data System (ADS)

D'Acunha, B.; Johnson, M. S.; Lee, S. C.; Christen, A.

2016-12-01

Peatlands are wetlands where gross primary production exceeds organic matter decomposition causing an accumulation of partially decomposed matter, also called peat. These ecosystems can accumulate more carbon than tropical rainforests. However, dissolved and gaseous fluxes of carbon (as dissolved organic carbon (DOC), CO2 and methane (CH4)) must also be considered to determine if these ecosystems are net sinks or sources of greenhouse gases (GHGs) to the atmosphere, which depends in part on the environmental conditions and the state of the ecosystem. We conducted research in Burns Bog, Delta, BC, Canada, a raised domed peat bog located in the Fraser River Delta and one of the largest raised peat bogs on the west coast of the Americas, but which has been heavily impacted by a range of human activities. Currently, ecological restoration efforts are underway by a large-scale ditch blocking program, with the aim to re-establish a high water table. This is approached in partnership with research on the ecosystem services that the bog provides, including its role in a regional GHG inventory. Here we present data on ecosystem-scale fluxes of CO2 and CH4 determined by eddy covariance (EC) on a floating tower platform, and complementary data on (i) evasion fluxes of CO2, CH4 and nitrous oxide (N2O) from the water surface to the atmosphere, and (ii) the flux and composition of dissolved organic carbon in water draining Burns Bog. Concentrations of dissolved CO2, CH4 and N2O were determined by headspace equilibration, and evasion rates from the water surface were quantified and are used to estimate the role of the hydrosphere in the ecosystem-scale measurements. Water samples collected from five saturated areas in the flux tower footprint were analyzed for DOC concentrations and composition. Results indicated that, even though the whole system is a net C sink, the water surface behaved as a source of CO2 and CH4, and a sink for N2O throughout the study period. Drainage waters were high in DOC (> 30 mg L-1). DOC export was found to offset about 20% of the apparent net C uptake determined by EC, indicating that the EC system overestimates carbon accumulation by not accounting for DOC drainage.

Greenhouse gas balance of blanket peat bog restoration from forestry in the Flow Country, Scotland

NASA Astrophysics Data System (ADS)

Hermans, Renée; Subke, Jens-Arne; Cowie, Neil; Arn Teh, Yit; Andersen, Roxane

2017-04-01

The Flow country in the far north of Scotland has the largest expanse of blanket peat bog in Europe. With peat depths of up to several metres, this area represents a significant carbon store. Large parts of the Flows were drained for afforestation with non-native conifers during the 1980s, which resulted in considerable damage to the peat, leading to significant carbon loss. To restore the peatland, the Royal Society for the Protection of Birds (RSPB) started in the late 1990s to fell trees and block drains. Over 2200 ha of forestry are felled. The main objective of this study is to measure the impact of forest removal on the budget of three main greenhouse gases, CO2, CH4 and N2O. Local variations in fluxes were measured using dark closed chambers. In order to capture abiotic conditions likely to determine microbial activity and therefor CO2, CH4 and N2O production, I record water table depth as well as soil moisture and soil temperature (both measured at 5 and 20 cm deep). These measurements are done in near pristine bog (control plot), in forest (control plot), in recently felled areas and in areas that were felled up to 19 years ago, creating a chronosequence to follow the effects of restoration. Results indicate only small differences in annual CO2 flux to the atmosphere between sites, with only the 19-year old restored site showing higher fluxes than forest control plots. However some seasonal differences in CO2 flux between land cover are evident. CH4 fluxes from forest are significantly lower than from bog and the site restored 17 years ago, and N2O fluxes are very low in all sites with no significant differences between sites. Sites where forests were removed recently (< 1 year previously) show a high degree of variability in CH4 fluxes, indicating potential flux spikes from disturbance. There is a positive correlation between soil temperature and CO2 and CH4 flux. Soil moisture varies a lot between bog, restored sites and forest, however there does not seem to be a direct correlation between soil moisture at the surface and CO2 and CH4 fluxes. Peatlands store big amounts of carbon, therefore there is a high level of importance to quantify the impact of various restoration techniques used.

Experimental Nitrogen Deposition Alters Post-fire Carbon Balance Recovery in Alberta Bogs

NASA Astrophysics Data System (ADS)

Wieder, R. K.; Vile, M. A.; Scott, K. D.; Albright, C. M.; McMillen, K.

2016-12-01

Bogs and fens occupy about 30% of the landscape across northern Alberta, Canada and function regionally as a net sink for atmospheric CO2-C, the strength of which is strongly influenced by the frequency and extent of wildfires. Alberta peatlands have persisted at the low end of the global range of annual atmospheric nitrogen (N) deposition (< 2 kg ha-1 yr-1), but oil sands development in the Athabasca Oil Sands Region has led to regionally elevated atmospheric N deposition. To examine the effects of elevated N deposition on bog net CO2 exchange, we experimentally applied N (as NH4NO3 solutions) to replicated plots at levels equivalent to controls (C: no water additions), 0 (water only), 10, and 20 kg/ha/yr at five bog sites, aged at 2, 12, 32, 73, and 113 years since fire in 2013 (hummocks and hollows in 6 plots per N treatment per site). Understory net ecosystem exchange of CO2 (NEE) was measured repeatedly throughout the 2013-2016 growing seasons using the closed chamber approach. Averaged across all years, sites, plots, and hummocks versus hollows, N addition stimulated NEE rates (C and 0 treatments: 0.46 µmol m-2 s-1; 10 and 20 treatments: 1.16 µmol m-2 s-1) and to a much lesser extent understory dark respiration (ER) rates (C and 0 treatments: -3.26 µmol m-2 s-1; 10 and 20 treatments: -3.43 µmol m-2 s-1). On an annual basis, averaged across all years, sites, and plots, N addition also stimulated NEE for hummocks (C and 0 treatments: -1.0 mol C m-2 yr-1; 10 and 20 treatments: 15.7 mol C m-2 yr-1), but not hollows. Experimental N addition had minimal effects on annual ER. The nature of the N response, however, differed between sites and years. Further, experimental N addition had no effect on the net primary production of Sphagnum fuscum, the dominant peat-forming moss. Thus, the enhancement of the net CO2-C sink through N addition occurs through stimulation of short-statured vascular shrub growth and biomass, with implications for the structure and function of bog understories as they recover after fire under different N deposition regimes.

Late Twentieth-Century Racial Uplift Work.

ERIC Educational Resources Information Center

Logan, Shirley Wilson

This paper presents a description and brief history of the concept of "racial uplift" and describes its implications for a contemporary, Black college professor. The phrase "racial uplift," for 19th-century Black women, describes almost any type of political activity designed to improve conditions for Black people during the…

Magmatic activity beneath the quiescent Three Sisters volcanic center, central Oregon Cascade Range, USA

USGS Publications Warehouse

Wicks, Charles W.; Dzurisin, Daniel; Ingebritsen, Steven E.; Thatcher, Wayne R.; Lu, Zhong; Iverson, Justin

2002-01-01

Images from satellite interferometric synthetic aperture radar (InSAR) reveal uplift of a broad ~10 km by 20 km area in the Three Sisters volcanic center of the central Oregon Cascade Range, ~130 km south of Mt. St. Helens. The last eruption in the volcanic center occurred ~1500 years ago. Multiple satellite images from 1992 through 2000 indicate that most if not all of ~100 mm of observed uplift occurred between September 1998 and October 2000. Geochemical (water chemistry) anomalies, first noted during 1990, coincide with the area of uplift and suggest the existence of a crustal magma reservoir prior to the uplift. We interpret the uplift as inflation caused by an ongoing episode of magma intrusion at a depth of ~6.5 km.

Uplift of quaternary shorelines in eastern Patagonia: Darwin revisited

NASA Astrophysics Data System (ADS)

Pedoja, Kevin; Regard, Vincent; Husson, Laurent; Martinod, Joseph; Guillaume, Benjamin; Fucks, Enrique; Iglesias, Maximiliano; Weill, Pierre

2011-04-01

During his journey on the Beagle, Darwin observed the uniformity in the elevation of coastal Eastern Patagonia along more than 2000 km. More than one century later, the sequences of Quaternary shorelines of eastern Patagonia have been described and their deposits dated but not yet interpreted in terms of geodynamics. Consequently, we i) mapped the repartition of the Quaternary coastal sequences in Argentinean Patagonia, ii) secured accurate altitudes of shoreline angles associated with erosional morphologies (i.e. marine terraces and notches), iii) took into account previous chrono-stratigraphical interpretations in order to calculate mean uplift rates since ~ 440 ka (MIS 11) and proposed age ranges for the higher and older features (up to ~ 180 m), and iv) focused on the Last Interglacial Maximum terrace (MIS 5e) as the best constrained marine terrace (in terms of age and altitude) in order to use it as a tectonic benchmark to quantify uplift rates along the entire passive margin of Eastern South America. Our results show that the eastern Patagonia uplift is constant through time and twice the uplift of the rest of the South American margin. We suggest that the enhanced uplift along the eastern Patagonian coast that interested Darwin during his journey around South America on the Beagle could originate from the subduction of the Chile ridge and the associated dynamic uplift.

Topographic form of the Coast Ranges of the Cascadia Margin in relation ot coastal uplift rates and plate subduction

NASA Technical Reports Server (NTRS)

Kelsey, Harvey M.; Engebretson, David C.; Mitchell, Clifton E.; Ticknor, Robert L.

1994-01-01

The Coast Ranges of the Cascadia margin are overriding the subducted Juan de Fuca/Gorda plate. We investigate the extent to which the latitudinal change in attributes related to the subduction process. These attributes include the varibale age of the subducted slab that underlies the Coast Ranges and average vertical crustal velocities of the western margin of the Coast Rnages for two markedly different time periods, the last 45 years and the last 100 kyr. These vertical crustal velocities are computed from the resurveying of highway bech marks and from the present elevation of shore platforms that have been uplifted in the late Quaternary, respectively. Topogarphy of the Coast Ranges is in part a function of the age and bouyancy of the underlying subducted plate. This is evident in the fact that the two highest topographic elements of the Coast Rnages, the Klamath Mountains and the Olympic Mountains, are underlain by youngest subducted oceanic crust. The subducted Blanco Fracture Zone in southernmost Oregon is responsible for an age discontinuity of subducted crust under the Klamath Mountains. The norhtern terminus of hte topographically higher Klamaths is offset to the north relative to the position of the underlying Blanco Fracture Zone, teh offset being in the direction of migration of the farcture zone, as dictated by relative plate motions. Vertical crustal velocities at the coast, derived from becnh mark surveys, are as much as an order of magnitude greater than vertical crustal velocities derived from uplifted shore platforms. This uplift rate discrepancy indicates that strain is accumulating on the plate margin, to be released during the next interplate earthquake. In a latitudinal sense, average Coast Rnage topography is relatively high where bench mark-derived, short-term vertical crustal velocities are highest. Becuase the shore platform vertical crustal velocities reflect longer-term, premanent uplift, we infer that a small percentage of the interseismic strain that accumulates as rapid short-term uplift is not recovered by subduction earthquakes but rather contributes to rock uplift of the Coast Ranges. The conjecture that permanent rock uplift is related to interseismic uplift is consistent with the observation that those segments of the subduction zone subject to greater interseismic uplift rates are at approximately the same latitudes as those segments of the Coast Ranges that have higher magnitudes of rock uplift over the long term.

Surface Uplift Rate Constrained by Multiple Terrestrial Cosmogenic Nuclides: Theory and Application from the Central Andean Plateau

NASA Astrophysics Data System (ADS)

McPhillips, D. F.; Hoke, G. D.; Niedermann, S.; Wittmann, H.

2015-12-01

There is widespread interest in quantifying the growth and decay of topography. However, prominent methods for quantitative determinations of paleoelevation rely on assumptions that are often difficult to test. For example, stable isotope paleoaltimetry relies on the knowledge of past lapse rates and moisture sources. Here, we demonstrate how cosmogenic 10Be - 21Ne and/or 10Be - 26Al sample pairs can be applied to provide independent estimates of surface uplift rate using both published data and new data from the Atacama Desert. Our approach requires a priori knowledge of the maximum age of exposure of the sampled surface. Ignimbrite surfaces provide practical sampling targets. When erosion is very slow (roughly, ≤1 m/Ma), it is often possible to constrain paleo surface uplift rate with precision comparable to that of stable isotopic methods (approximately ±50%). The likelihood of a successful measurement is increased by taking n samples from a landscape surface and solving for one regional paleo surface uplift rate and n local erosion rates. In northern Chile, we solve for surface uplift and erosion rates using three sample groups from the literature (Kober et al., 2007). In the two lower elevation groups, we calculate surface uplift rates of 110 (+60/-12) m/Myr and 160 (+120/-6) m/Myr and estimate uncertainties with a bootstrap approach. The rates agree with independent estimates derived from stream profile analyses nearby (Hoke et al., 2007). Our calculated uplift rates correspond to total uplift of 1200 and 850 m, respectively, when integrated over appropriate timescales. Erosion rates were too high to reliably calculate the uplift rate in the third, high elevation group. New cosmogenic nuclide analyses from the Atacama Desert are in progress, and preliminary results are encouraging. In particular, a replicate sample in the vicinity of the first Kober et al. (2007) group independently yields a surface uplift rate of 110 m/Myr. Compared to stable isotope proxies, cosmogenic nuclides potentially provide better constraints on surface uplift in places where assumptions about paleo-atmospheric conditions are hard to constrain and justify. F. S. Kober et al. (2007), Geomorphology, 83, 97-110. G. D. Hoke et al. (2007), Tectonics, 26, doi:10.1029/2006TC002082.

Geochronological and sedimentological evidences of Panyangshan foreland basin for tectonic control on the Late Paleozoic plate marginal orogenic belt along the northern margin of the North China Craton

NASA Astrophysics Data System (ADS)

Li, Jialiang; Zhou, Zhiguang; He, Yingfu; Wang, Guosheng; Wu, Chen; Liu, Changfeng; Yao, Guang; Xu, Wentao; Zhao, Xiaoqi; Dai, Pengfei

2017-08-01

There is a wide support that the Inner Mongolia Palaeo-uplift on the northern margin of the North China Craton has undergone an uplifting history. However, when and how did the uplift occurred keeps controversial. Extensive field-based structural, metamorphic, geochemical, geochronological and geophysical investigations on the Inner Mongolia Palaeo-uplift, which suggested that the Inner Mongolia Palaeo-uplift was an uplifted region since the Early Precambrian or range from Late Carboniferous-Early Jurassic. The geochemical characteristics of the Late Paleozoic to Early Mesozoic intrusive rocks indicated that the Inner Mongolia Palaeo-uplift was an Andean-type continental margin that is the extensional tectonic setting. To address the spatial and temporal development of the Inner Mongolia Palaeo-uplift, we have carried out provenance analysis of Permian sedimentary rocks which collected from the Panyangshan basin along the northern margin of the North China Craton. The QFL diagram revealed a dissected arc-recycled orogenic tectonic setting. Moreover, the framework grains are abundant with feldspar (36-50%), indicating the short transport distance and unstable tectonic setting. Detrital zircon U-Pb analysis ascertained possible provenance information: the Precambrian basement ( 2490 and 1840 Ma) and continental arc magmatic action ( 279 and 295 Ma) along the northern margin of the North China Craton. The projection in rose diagrams of the mean palaeocurrent direction, revealing the SSW and SSE palaeoflow direction, also shows the provenance of the Panyangshan basin sources mainly from the Inner Mongolia Palaeo-uplift. The andesite overlying the Naobaogou Formation has yielded U-Pb age of 277.3 ± 1.4 Ma. The additional dioritic porphyry dike intruded the Naobaogou and Laowopu Formations, which has an emplacement age of 236 ± 1 Ma. The above data identify that the basin formed ranges from Early Permian to Middle Triassic (277-236 Ma). Accordingly, the Inner Mongolia Palaeo-uplift also was developed in the Early Permian to Middle Triassic (277-236 Ma), related to the final closure of the Paleo-Asian Ocean. Furthermore, we advocate that the tectonic setting of Inner Mongolia Palaeo-uplift probably belonged to the plate marginal orogenic belt during Early Permian-Middle Triassic.

Elastic expansion of the lithosphere caused by groundwater withdrawal in south-central Arizona

USGS Publications Warehouse

Holzer, T.L.

1979-01-01

Relative crustal uplift observed from 1948-1949 to 1967 in the Lower Santa Cruz River Basin in south-central Arizona is attributed at least in part to elastic expansion of the lithosphere induced by the removal, and subsequent loss by evapo transpiration, of 4.35 ?? 1013 kg of groundwater from alluvium. The area of unloading is approximately 8070 km2. Uplift, relative to an apparently stable area west of the unloaded area, was observed in two areas near Casa Grande and Florence where crystalline bedrock is either close to the land surface or crops out through alluvium from which groundwater was withdrawn. The magnitudes of uplift were approximately 6.3 and 7.5 cm respectively. The observations are based on first-order leveling. The observations are significant at three standard deviations for random surveying errors, and are not believed to be affected by systematic errors. However, the 7.5-cm uplift observed at Florence may be from 1 to 2 cm in excess of the actual uplift because of the possibility of subsidence of a tie point due to groundwater pumping during the leveling in 1948-1949. Uplift is attributed to groundwater withdrawal on three bases. First, the observed uplift is consistent with a theoretical evaluation of elastic expansion based on linear elasticity theory. For the observed distribution of unloading and uplift and a Poisson's ratio of 0.25, a Young's modulus for the lithosphere of approximately 0.68 Mbar is implied. This value is comparable to values of the lithosphere reported elsewhere. Second, the magnitude of uplift compares favorably with the magnitude of elastic depression caused by the formation of Lake Mead, Arizona-Nevada, 430 km northwest of the study area, when allowance is made for the different magnitudes and areal distributions of surface (un)loading. And third, in the area near Casa Grande, a reversal in the sense of bedrock displacement form subsidence of tectonic origin to uplift approximately coincided with the beginning of large groundwater overdraft. The uplift from 1948 to 1967 near Casa Grande was preceded from 1905 to 1948 by 7-8 cm of tectonic subsidence; no precise data for the area near Florence are available before 1948. ?? 1979.

Geochronological and sedimentological evidences of Panyangshan foreland basin for tectonic control on the Late Paleozoic plate marginal orogenic belt along the northern margin of the North China Craton

NASA Astrophysics Data System (ADS)

Li, Jialiang; Zhou, Zhiguang; He, Yingfu; Wang, Guosheng; Wu, Chen; Liu, Changfeng; Yao, Guang; Xu, Wentao; Zhao, Xiaoqi; Dai, Pengfei

2018-06-01

There is a wide support that the Inner Mongolia Palaeo-uplift on the northern margin of the North China Craton has undergone an uplifting history. However, when and how did the uplift occurred keeps controversial. Extensive field-based structural, metamorphic, geochemical, geochronological and geophysical investigations on the Inner Mongolia Palaeo-uplift, which suggested that the Inner Mongolia Palaeo-uplift was an uplifted region since the Early Precambrian or range from Late Carboniferous-Early Jurassic. The geochemical characteristics of the Late Paleozoic to Early Mesozoic intrusive rocks indicated that the Inner Mongolia Palaeo-uplift was an Andean-type continental margin that is the extensional tectonic setting. To address the spatial and temporal development of the Inner Mongolia Palaeo-uplift, we have carried out provenance analysis of Permian sedimentary rocks which collected from the Panyangshan basin along the northern margin of the North China Craton. The QFL diagram revealed a dissected arc-recycled orogenic tectonic setting. Moreover, the framework grains are abundant with feldspar (36-50%), indicating the short transport distance and unstable tectonic setting. Detrital zircon U-Pb analysis ascertained possible provenance information: the Precambrian basement ( 2490 and 1840 Ma) and continental arc magmatic action ( 279 and 295 Ma) along the northern margin of the North China Craton. The projection in rose diagrams of the mean palaeocurrent direction, revealing the SSW and SSE palaeoflow direction, also shows the provenance of the Panyangshan basin sources mainly from the Inner Mongolia Palaeo-uplift. The andesite overlying the Naobaogou Formation has yielded U-Pb age of 277.3 ± 1.4 Ma. The additional dioritic porphyry dike intruded the Naobaogou and Laowopu Formations, which has an emplacement age of 236 ± 1 Ma. The above data identify that the basin formed ranges from Early Permian to Middle Triassic (277-236 Ma). Accordingly, the Inner Mongolia Palaeo-uplift also was developed in the Early Permian to Middle Triassic (277-236 Ma), related to the final closure of the Paleo-Asian Ocean. Furthermore, we advocate that the tectonic setting of Inner Mongolia Palaeo-uplift probably belonged to the plate marginal orogenic belt during Early Permian-Middle Triassic.

Plate-mantle interaction through time explains two-phase uplift history of the eastern Australian passive margin

NASA Astrophysics Data System (ADS)

Dietmar Müller, R.; Flament, Nicolas; Matthews, Kara J.; Williams, Simon E.; Gurnis, Michael

2015-04-01

The origin of passive margin mountains is a hotly debated topic in geodynamics. The Eastern Highlands of Australia are a type example whose uplift history has been investigated for several decades, with suggested mechanisms ranging from flexural rift shoulder uplift, volcanism and underplating to mantle-convection driven dynamic topography. Most of the highlands have experienced a distinct two-phase uplift history, with the first phase being Late Cretaceous in age, followed by a mid-late Cenozoic renewal in uplift, but the timing and magnitude of uplift differs along strike. We investigate the origin of the Eastern Highlands with a coupled plate-mantle model, using a thorough parameter space analysis, including two alternative subduction boundary evolution models. The first model includes a large (~1000 km width at its maximum extent) Early Cretaceous (140-120 Ma) back-arc basin east of the Lord Howe Rise, representing the now subducted South Loyalty Basin which may have formed due to eastward rollback of the long-lived west-dipping eastern Gondwanaland subduction zone; the alternative scenario is based on the premise that west-dipping subduction is continuous to the East of the Lord Howe Rise between 140-85 Ma, without a large back-arc basin, and the South Loyalty Basin opening as a back arc basin from 85-55 Ma, which is subsequently consumed by subduction. We further investigate the influence of a low-viscosity asthenosphere and of the viscosity profile of the lower mantle on dynamic topography, as well as the effect of changing the buoyancy of the basal dense layer (LLSVP) that contributes to the long-wavelength Pacific superswell. Our best-fit model produces a total uplift up to ~400 m in the interval between 120 and 90-70 Ma, well-matched with recent published estimates from river profile inversion for the Snowy Mountains, New England and the Central Highlands. The driving mechanism is rebound from the eastwards motion of Australia over a sinking slab, first leading to transient subsidence and continental flooding followed by rebound and uplift. Our model predicts cessation of uplift from 70-40 Ma (Snowy Mountains), 90-60 Ma (New England), followed by renewed uplift of up to 200 m. In the Central Highlands we model continuing, but distinctly slower uplift from 90Ma to the present, also totaling ~200m. The mechanism represents the gradual motion of Eastern Australia over the edge of the southwest Pacific superswell. The Central Highlands experienced the influence of the perimeter of the superswell first, due to their more northerly location, more proximal to the swell's edge, resulting in a continuous history of uplift since the mid-Cretaceous, whereas the Snowy Mountains started interacting with the superswell edge ~40-50 my later, resulting in a distinct break in uplift. The magnitude of the 2nd phase of uplift from river profile inversion versus geodynamic modeling matches well for the Central Highlands, but not further south. We attribute this to the lack of plumes in our current geodynamic models; plumes have clearly played an additional, important role in exacerbating uplift in the Late Cenozoic in the southern highlands, as indicated by the abundant, time-progressive Late Cenozoic volcanism in Eastern Australia.

Mid- and late Holocene human impact recorded by the Coltrondo peat bog (NE Italian Alps)

NASA Astrophysics Data System (ADS)

Segnana, Michela; Poto, Luisa; Gabrieli, Jacopo; Martino, Matteo; Oeggl, Klaus; Barbante, Carlo

2016-04-01

Peat bogs are ideal archives for the study of environmental changes, whether these are natural or human induced. Indeed, receiving water and nutrients exclusively from dry and wet atmospheric depositions, they are among the most suitable matrices for palaeoenvironmental reconstruction. The present study is focused on the Eastern sector of the Italian Alps, where we sampled the Coltrondo peat bog, in the Comelico area (ca. 1800 m a.s.l.) The knowledge of the human history in this area is rather scarce: the only pieces of archaeological evidence found in this area dates back to the Mesolithic and the absence of later archaeological finds makes it difficult to reconstruct the human settlement in the valley. With the main aim to obtain information about the human settlement in that area we selected a multi-proxy approach, combining the study of biotic and abiotic sedimentary components archived in the 7900 years-peat bog record. Pollen analysis is performed along the core registering human impacts on the area from ca. 2500 cal BP, when land-use changes are well evidenced by the presence of human-related pollen and non-pollen palynomorphs (NPPs), as well as by the increase in micro-charcoal particles. Periods of increased human impact are recorded at the end of the Middle Ages and later, at the end of the 19th century. The analysis of trace elements, such as lead, is performed by means of ICP-MS technique and its enrichment factor (EF) is calculated. A first slight increase of Pb EF during Roman Times is possibly related to mining activities carried out by the Romans. Mining activities carried out in the area are registered during the Middle Ages, while the advent of the industrialization in the 20th century is marked by the highest EF values registered on the top of the core. To help and support the interpretation of geochemical data, lead isotopes ratios are also measured using ICP-MS to discriminate between natural and anthropogenic sources of lead. The 206Pb/207Pb ratio clearly records a pre-anthropogenic period from 7800 to 2500 cal BP, followed by a period in which humans impacted on the environment. During the Middle Ages the 206Pb/207Pb ratio values are attributable to mining activities, while during Modern Times they are mostly linked to industrial activities and to the introduction of leaded gasoline in Italy. The phasing out of leaded gasoline in the 1980s is also registered by the peat bog. Finally, the still on-going analysis of organic biomarkers in the peat seems to corroborate the results achieved, adding information about local disturbances on the bog. The multi-proxy approach selected for this study allows us to discriminate between different aspects of the past human presence, such as forest clearance, fires, agriculture, pasture, mining and industrial activities, giving new insights into the history of the Comelico area, still scarcely investigated.

The geology, botany and chemistry of selected peat-forming environments from temperate and tropical latitudes

USGS Publications Warehouse

Cameron, C.C.; Esterle, J.S.; Palmer, C.A.

1989-01-01

Peat has been studied in several geologic settings: (1) glaciated terrain in cold temperate Maine and Minnesota, U.S.A.; (2) an island in the Atlantic Ocean off the coast of Maine, where sea level is rising; (3) the warm temperate U.S. Atlantic and Gulf Coastal Plains, where sea level has changed often; and (4) the tropical coast of Sarawak, Malaysia, and the tropical delta of the Batang Hari River, Sumatra, Indonesia. Most of these deposits are domed (ombrotrophic or partly ombrotrophic) bogs in which peat accumulation continued above the surface of the surrounding soil. However, the bogs of the U.S. Atlantic and Gulf Coastal Plains are comparatively not as domed, and many have almost level surfaces. In some bogs, aquatic or semi-aquatic plant materials accumulated, replaced water in the depressions, and formed a surface on which marsh or swamp vegetation could subsequently live, die, and accumulate. In others, the plant materials accumulated initially on level silt or sand surfaces supporting marshes or swamps. As the peat dome formed, plants growing on it changed from luxuriant ones near the base of the dome, where nutrients were brought into the bog by surface and ground water, to stunted ones at the top of the dome, where the raised bogs are fed by nutrient-poor precipitation. The physical and chemical changes that take place in the sequence of environments from the pond stage of deposit development, through the grassy marsh stage, through the forested swamp stage, and finally through the heath dome stage can be measured in terms of acidity and ash, volatile matter, carbon, hydrogen, nitrogen, sulfur and oxygen contents, as well as in the kind and distribution of trace elements. The organic and inorganic contents of the deposits relate to geomorphology, and geomorphology relates to their settings. As models of coal formation, some domed peat deposits may help in solving problems of distribution and character of ancient coal beds. But clearly not all peat deposits are precursors of coal. Most Holocene peat deposits are subject to destruction by erosion, fire and decomposition through microbial and chemical oxidation before burial. The best environments for coal precursors have biomass accumulation, a continuously rising water table within the mass, and minimum influx of clay and silt until preservation by burial. The most suitable settings for future economic coal deposits are domed bogs that accumulate thick, widespread peat having low ash and low sulfur contents. The ombrotrophic peat deposits of tropical Sarawak and Sumatra are thick and extensive, contain low-ash and low-sulfur peat, and have high heating values. They are considered to be the best tropical coal analogs because of their extent and chances of preservation; the base of the peat is below adjacent river levels, and chemical and structural conditions are favorable for accumulation. ?? 1989.

Linking erosion history and mantle processes in southern Africa

NASA Astrophysics Data System (ADS)

Stanley, J. R.; Braun, J.; Flowers, R. M.; Baby, G.; Wildman, M.; Guillocheau, F.; Robin, C.; Beucher, R.; Brown, R. W.

2017-12-01

The large, low relief, high elevation plateau of southern Africa has been the focus of many studies, but there is still considerable debate about how it formed. Lack of tectonic convergence and crustal thickening suggests mantle dynamics play an important role in the evolution of topography there, but the time and specific mechanisms of topographic development are still contested. Many mantle mechanisms of topographic support have been suggested including dynamic topography associated with either deep or shallow mantle thermal anomalies, thermochemical modification of the lithosphere, and plume tails related to Mesozoic magmatic activity. These mechanisms predict different timing and patterns of surface uplift such that better constraints on the uplift history have the potential to constrain the nature of the source of topographic support. Here we test several of these geodynamic hypotheses using a landscape evolution model that is used to predict the erosional response to surface uplift. Several recent studies have provided a clearer picture of the erosion history of the plateau surface and margins using low temperature thermochronology and the geometries of the surrounding offshore depositional systems. Model results are directly compared with these data. We use an inversion method (the Neighborhood Algorithm) to constrain the range in erosional and uplift parameters that can best reproduce the observed data. The combination of different types of geologic information including sedimentary flux, landscape shape, and thermochronolology is valuable for constraining many of these parameters. We show that both the characteristics of the geodynamic forcing as well as the physical characteristics of the eroding plateau have significant control on the plateau erosion patterns. Models that match the erosion history data well suggest uplift of the eastern margin in the Cretaceous ( 100 Ma) followed by uplift of the western margin 20 Myr later. The amplitude of this uplift is on the order of 1000 m. The data cannot resolve whether there was smaller amplitude phase of uplift in the Cenozoic. These results suggest that the scenario proposed by Braun et al. (2014) of uplift caused by the continent moving over the African superswell is viable. We are currently investigating the compatibility of other uplift geometries.

Linear Inverse Modeling and Scaling Analysis of Drainage Inventories.

NASA Astrophysics Data System (ADS)

O'Malley, C.; White, N. J.

2016-12-01

It is widely accepted that the stream power law can be used to describe the evolution of longitudinal river profiles. Over the last 5 years, this phenomenological law has been used to develop non-linear and linear inversion algorithms that enable uplift rate histories to be calculated by minimizing the misfit between observed and calculated river profiles. Substantial, continent-wide inventories of river profiles have been successfully inverted to yield uplift as a function of time and space. Erosional parameters can be determined by independent geological calibration. Our results help to illuminate empirical scaling laws that are well known to the geomorphological community. Here we present an analysis of river profiles from Asia. The timing and magnitude of uplift events across Asia, including the Himalayas and Tibet, have long been debated. River profile analyses have played an important role in clarifying the timing of uplift events. However, no attempt has yet been made to invert a comprehensive database of river profiles from the entire region. Asian rivers contain information which allows us to investigate putative uplift events quantitatively and to determine a cumulative uplift history for Asia. Long wavelength shapes of river profiles are governed by regional uplift and moderated by erosional processes. These processes are parameterised using the stream power law in the form of an advective-diffusive equation. Our non-negative, least-squares inversion scheme was applied to an inventory of 3722 Asian river profiles. We calibrate the key erosional parameters by predicting solid sedimentary flux for a set of Asian rivers and by comparing the flux predictions against published depositional histories for major river deltas. The resultant cumulative uplift history is compared with a range of published geological constraints for uplift and palaeoelevation. We have found good agreement for many regions across Asia. Surprisingly, single values of erosional constants can be shown to produce reliable uplift histories. However, these erosional constants appear to vary from continent to continent. Future work will investigate the global relationship between our inversion results, scaling laws, climate models, lithological variation and sedimentary flux.

Shelf width and river base level on active margins controlled by a combination of eustasy and local uplift rate, illustration from the Pacific NW of the United States.

NASA Astrophysics Data System (ADS)

Malatesta, L. C.; Finnegan, N. J.; Kushwaha, G.

2017-12-01

Sea level defines the elevation where wave-base erosion is the dominant erosive process. Hence, submarine erosion of the margin and creation of a continental shelf depend on the time distribution of sea level relative to bedrock by correcting eustasy for local rock uplift. Eustasy and wave-base erosion also impact most fluvial systems on Earth by affecting the vertical and lateral position of their lower boundary condition, the coastline. When uplift rate is slow, the concentration of wave-base erosion on a restricted range of elevation promotes the creation of wide shelves and of a relatively stable average base level for coastal rivers. While interfluves above the shelf are steep, fluvial valleys in slow uplift regions grade into the shelf and form estuaries that trap sediment at high stand. Alternatively, a fast coastal uplift rate distributes wave-base erosion over a wide range of bedrock elevations that are quickly uplifted above the eustatic range, preventing the beveling of a shelf and the establishment of a river profile equilibrated around an average sea-level. In that case, river base level is highly dependent on the gradient of the continental slope. We show that the width of the shelf is inversely correlated with the uplift rate along the Oregon and northern California coast. The extent of the shelf can be a valuable counterpart to (often absent) marine terraces that provides a record for coastline retreat, local uplift rate and river base level.

Mechanism for generating the anomalous uplift of oceanic core complexes: Atlantis Bank, southwest Indian Ridge

NASA Astrophysics Data System (ADS)

Baines, A. Graham; Cheadle, Michael J.; Dick, Henry J. B.; Hosford Scheirer, Allegra; John, Barbara E.; Kusznir, Nick J.; Matsumoto, Takeshi

2003-12-01

Atlantis Bank is an anomalously uplifted oceanic core complex adjacent to the Atlantis II transform, on the southwest Indian Ridge, that rises >3 km above normal seafloor of the same age. Models of flexural uplift due to detachment faulting can account for ˜1 km of this uplift. Postdetachment normal faults have been observed during submersible dives and on swath bathymetry. Two transform-parallel, large-offset (hundreds of meters) normal faults are identified on the eastern flank of Atlantis Bank, with numerous smaller faults (tens of meters) on the western flank. Flexural uplift associated with this transform-parallel normal faulting is consistent with gravity data and can account for the remaining anomalous uplift of Atlantis Bank. Extension normal to the Atlantis II transform may have occurred during a 12 m.y. period of transtension initiated by a 10° change in spreading direction ca. 19.5 Ma. This extension may have produced the 120-km-long transverse ridge of which Atlantis Bank is a part, and is consistent with stress reorientation about a weak transform fault.

Mechanism for generating the anomalous uplift of oceanic core complexes: Atlantis Bank, southwest Indian Ridge

USGS Publications Warehouse

Baines, A.G.; Cheadle, Michael J.; Dick, H.J.B.; Scheirer, A.H.; John, Barbara E.; Kusznir, N.J.; Matsumoto, T.

2003-01-01

Atlantis Bank is an anomalously uplifted oceanic core complex adjacent to the Atlantis II transform, on the southwest Indian Ridge, that rises >3 km above normal seafloor of the same age. Models of flexural uplift due to detachment faulting can account for ???1 km of this uplift. Postdetachment normal faults have been observed during submersible dives and on swath bathymetry. Two transform-parallel, large-offset (hundreds of meters) normal faults are identified on the eastern flank of Atlantis Bank, with numerous smaller faults (tens of meters) on the western flank. Flexural uplift associated with this transform-parallel normal faulting is consistent with gravity data and can account for the remaining anomalous uplift of Atlantis Bank. Extension normal to the Atlantis II transform may have occurred during a 12 m.y. period of transtension initiated by a 10?? change in spreading direction ca. 19.5 Ma. This extension may have produced the 120-km-long transverse ridge of which Atlantis Bank is a part, and is consistent with stress reorientation about a weak transform fault.

Determination of sub-daily glacier uplift and horizontal flow velocity with time-lapse images using ImGRAFT

NASA Astrophysics Data System (ADS)

Egli, Pascal; Mankoff, Ken; Mettra, François; Lane, Stuart

2017-04-01

This study investigates the application of feature tracking algorithms to monitoring of glacier uplift. Several publications have confirmed the occurrence of an uplift of the glacier surface in the late morning hours of the mid to late ablation season. This uplift is thought to be caused by high sub-glacial water pressures at the onset of melt caused by overnight-deposited sediment that blocks subglacial channels. We use time-lapse images from a camera mounted in front of the glacier tongue of Haut Glacier d'Arolla during August 2016 in combination with a Digital Elevation Model and GPS measurements in order to investigate the phenomenon of glacier uplift using the feature tracking toolbox ImGRAFT. Camera position is corrected for all images and the images are geo-rectified using Ground Control Points visible in every image. Changing lighting conditions due to different sun angles create substantial noise and complicate the image analysis. A small glacier uplift of the order of 5 cm over a time span of 3 hours may be observed on certain days, confirming previous research.

Uplifting behavior of shallow buried pipe in liquefiable soil by dynamic centrifuge test.

PubMed

Huang, Bo; Liu, Jingwen; Lin, Peng; Ling, Daosheng

2014-01-01

Underground pipelines are widely applied in the so-called lifeline engineerings. It shows according to seismic surveys that the damage from soil liquefaction to underground pipelines was the most serious, whose failures were mainly in the form of pipeline uplifting. In the present study, dynamic centrifuge model tests were conducted to study the uplifting behaviors of shallow-buried pipeline subjected to seismic vibration in liquefied sites. The uplifting mechanism was discussed through the responses of the pore water pressure and earth pressure around the pipeline. Additionally, the analysis of force, which the pipeline was subjected to before and during vibration, was introduced and proved to be reasonable by the comparison of the measured and the calculated results. The uplifting behavior of pipe is the combination effects of multiple forces, and is highly dependent on the excess pore pressure.

Abrupt uplift within the past 1700 years at Southern Puget Sound, Washington

USGS Publications Warehouse

Bucknam, R.C.; Hemphill-Haley, E.; Leopold, E.B.

1992-01-01

Shorelines rose as much as 7 meters along southern Puget Sound and Hood Canal between 500 and 1700 years ago. Evidence for this uplift consists of elevated wave-cut shore platforms near Seattle and emerged, peat-covered tidal flats as much as 60 kilometers to the southwest. The uplift was too rapid for waves to leave intermediate shorelines on even the best preserved platform. The tidal flats also emerged abruptly; they changed into freshwater swamps and meadows without first becoming tidal marshes. Where uplift was greatest, it adjoined an inferred fault that crosses Puget Sound at Seattle and it probably accompanied reverse slip on that fault 1000 to 1100 years ago. The uplift and probable fault slip show that the crust of the North America plate contains potential sources of damaging earthquakes in the Puget Sound region.

Present-day vertical deformation of the Cascadia margin, Pacific Northwest, United States

NASA Astrophysics Data System (ADS)

Mitchell, Clifton E.; Vincent, Paul; Weldon, Ray J., III; Richards, Mark A.

1994-06-01

We estimate present-day uplift rates along hte Cascadia Subduction Zone in California, Oregon, and Washington in the Pacific Northwest, United States, by utilizing repeated leveling surveys and tide guage records. These two independent data sets give similar profiles for latitudinal variation of contemporary uplift rates along the coast. Uplift rates are extended inland through east-west leveling lines that connect the north-south line along hte coast to the north-south line along the inland valleys just west of the Cascades. The results are summarized as a contour map of present day uplift rates for the western Pacific Northwest. We find that rates of present day uplift vary latitudinally along the coast to the inland valleys. Long-term tial records of Neah Bay, Astoria, and Crescent City indicate uplift of land relative to sea level of 1.6 +/- 0.2, 0.0 +/- 0.2, 0.9 +/- 0.2 mm/yr, respectively (+/- 1 standard error). Unlike previous estimates of relative sea level change at Astoria, we adjust for discharge effects of the Columbia River, including human managment influences. After approximating an absolute framework by using 1.8 +/- 0.1 mm/yr to compensate for global sea level rise, results indicate that much of the western Pacific Northwest is rising at rates between 0 and 5 mm/ur. The most rapid uplift rates are near the coast, particularly near the Olympic Peninsula, the mouth of the Columbia River, Cape Blanco, and Cape Mendocino. Two axes of uplift are identified: one trends northeast from the southwest Oregon coast, and the other strends south-southeasterly from the Olympic Peninsula to the Columbia River. The Puget Sound vicinity and a small east-west region from the north cnetral Oregon coast ot he inland Willamette Valley are subiding at rates up to 1 mm/ur. We interpret the overall pattern of rapid present day uplift to be generated by interseismic strain accumulation in the subduction zone. This interseismic elastic strain accumulation implies significant seismic hazard.

Identification of Patients Expected to Benefit from Electronic Alerts for Acute Kidney Injury.

PubMed

Biswas, Aditya; Parikh, Chirag R; Feldman, Harold I; Garg, Amit X; Latham, Stephen; Lin, Haiqun; Palevsky, Paul M; Ugwuowo, Ugochukwu; Wilson, F Perry

2018-06-07

Electronic alerts for heterogenous conditions such as AKI may not provide benefit for all eligible patients and can lead to alert fatigue, suggesting that personalized alert targeting may be useful. Uplift-based alert targeting may be superior to purely prognostic-targeting of interventions because uplift models assess marginal treatment effect rather than likelihood of outcome. This is a secondary analysis of a clinical trial of 2278 adult patients with AKI randomized to an automated, electronic alert system versus usual care. We used three uplift algorithms and one purely prognostic algorithm, trained in 70% of the data, and evaluated the effect of targeting alerts to patients with higher scores in the held-out 30% of the data. The performance of the targeting strategy was assessed as the interaction between the model prediction of likelihood to benefit from alerts and randomization status. The outcome of interest was maximum relative change in creatinine from the time of randomization to 3 days after randomization. The three uplift score algorithms all gave rise to a significant interaction term, suggesting that a strategy of targeting individuals with higher uplift scores would lead to a beneficial effect of AKI alerting, in contrast to the null effect seen in the overall study. The prognostic model did not successfully stratify patients with regards to benefit of the intervention. Among individuals in the high uplift group, alerting was associated with a median reduction in change in creatinine of -5.3% ( P =0.03). In the low uplift group, alerting was associated with a median increase in change in creatinine of +5.3% ( P =0.005). Older individuals, women, and those with a lower randomization creatinine were more likely to receive high uplift scores, suggesting that alerts may benefit those with more slowly developing AKI. Uplift modeling, which accounts for treatment effect, can successfully target electronic alerts for AKI to those most likely to benefit, whereas purely prognostic targeting cannot. Copyright © 2018 by the American Society of Nephrology.

Aseismic fold growth in southwestern Taiwan detected by InSAR and GNSS

NASA Astrophysics Data System (ADS)

Tsukahara, Kotaro; Takada, Youichiro

2018-03-01

We report very rapid and aseismic fold growth detected by L-band InSAR images and GNSS data in southwestern Taiwan where is characterized by high convergence rate and low seismicity. Six independent interferograms acquired from ascending orbit during 2007-2011 commonly indicate large line-of-sight (LOS) shortening. For descending orbit, one interferogram spanning 21 months also indicates the LOS shortening at the same location. After removing long-wavelength noise and height-dependent phase component from these interferograms using GNSS velocity field and DEM, we obtained the quasi-vertical and the quasi-east velocity fields. We found very rapid uplift (quasi-vertical movement) in the fold and thrust belt to the east of the Tainan city. The uplifted area stretches about 25 km in the N-S direction and about 5 km in the E-W direction. At the southern part of the uplifted area, the uplift rate obtained by InSAR is consistent with that measured by the leveling survey, which takes 18 mm/year at a maximum. On the other hand, at the northern part, the maximum uplift rate detected by InSAR reaches up to 37 mm/year, more than twice as large as the rate along the levelling route. Judging from very low seismicity in this region, the severe crustal deformation we detected with InSAR is aseismic. At the eastern flank of the uplifted area, we found a sharp discontinuity in the uplift rate from the ALOS/PALSAR interferometry, and a sharp discontinuity in the amount of uplift in response to the 2016 Meinong earthquake (M6.4) from ALOS-2/PALSAR2 interferometry, which implies the existence of a shallow active fault. The stable slip of this active fault would be due to the high pore fluid pressure reported in this region. The aseismic uplift before the Meinong earthquake would be mainly due to the mud diapirs at the depth, which is perturbed by the aseismic movement of the shallow active fault.

Modelling and simulation of Holocene marine terrace development in Boso Peninsula, central Japan

NASA Astrophysics Data System (ADS)

Noda, Akemi; Miyauchi, Takahiro; Sato, Toshinori; Matsu'ura, Mitsuhiro

2018-04-01

In the southern part of Boso Peninsula, central Japan, we can observe a series of well-developed Holocene marine terraces. We modeled the development of these marine terraces by considering sea-level fluctuation and steady land uplift. The evolution of coastal landform is generally described as follows: altitude change = - erosion + deposition - sea-level rise + land uplift. In this study, the erosion rate is supposed to be proportional to the dissipation rate of wave energy, and the deposition rate of eroded materials to decay exponentially as they are transported seaward. The rate of sea-level rise is given by the time derivative of a sea-level curve obtained from the sediment core records of oxygen isotope ratios. Steady plate subduction generally brings about steady crustal uplift/subsidence independently of earthquake occurrence, and so the land-uplift rate is regarded as time independent on a long-term average. Our simulation results show that a pair of sea cliff and abrasion platform is efficiently formed about a stationary point of the sea-level curve. The Holocene sea-level curve has four peaks and three troughs, and so basically seven terraces are formed one by one during the past 10,000 yr. However, when the land-uplift rate is low, most of the terraces formed at older times sink in the sea. When the land-uplift rate is high, the overlap and/or reverse of older and younger terraces occur frequently, and so the correspondence between the age and present altitude of terraces is not necessarily one-to-one. Taking the land-uplift rate to be 3-4 mm/yr, we can reproduce a series of well-developed Holocene marine terraces in Boso Peninsula independently of coseismic uplifts. From these simulation results, we may conclude that the Holocene marine terraces in Boso Peninsula were developed as a result of the composite process of sea-level fluctuation and steady coastal uplift.

From ocean depths to mountain tops: uplift of the Troodos Massif (Cyprus) constrained by (U-Th)/He thermochronology and geomorphic analysis

NASA Astrophysics Data System (ADS)

Morag, N.; Haviv, I.; Katzir, Y.

2013-12-01

The Troodos Massif of Cyprus, rising to nearly 2000 meters above sea level, encompasses one of the world's classic ophiolites. Following its formation at a seafloor spreading center in Late Cretaceous times, this slice of the NeoTethyan oceanic lithosphere was uplifted and eventually exposed on mountain tops during the Neogene. The final uplift and exhumation of the Troodos was previously assigned to Pleistocene age by observations in the circum-Troodos sedimentary strata. However, quantitative thermochronological and geomorphological data from the Massif itself were not available. Here we use apatite (U-Th)/He low-temperature thermochronology complemented by zircon (U-Th)/He and apatite fission track data, and combined with geomorphic analysis to constrain the exhumation and uplift history of the Troodos ophiolite. Apatite (U-Th)/He ages vary with depth from ~ 22 Ma at the top of the Gabbro sequence to ~ 6 Ma at the bottom of the sequence. The deepest sample from a Gabbro pegmatitic dyke intruding the ultramafic sequence yielded an age of ~ 3 Ma. Thermal modeling of apatite (U-Th)/He and fission track data delineates Plio - Pleistocene initiation of rapid uplift and exhumation of the Troodos ophiolite. The estimated cumulative exhumation since its initiation is 2-3 km. No evidence was found for significant uplift of the central Troodos area prior to that time. The geomorphic analysis delineates a bull's-eye zone at the center of the Troodos Massif, where local relief and channel steepness index are highest. The boundaries of this zone roughly correspond with the Mt. Olympus mantle outcrop and suggest recent, differential uplift of this zone relative to its surroundings. The most likely mechanism, which could drive such a focused bull's-eye uplift pattern is hydration of ultramafic rocks (serpentinization) leading to a decrease in rock density and subsequent diapiric uplift of the serpentinized lithospheric mantle.

Structural Evolution of Martin Crater Thaumasia Planum, Mars

NASA Astrophysics Data System (ADS)

Dolan, Daniel J.

A detailed structural map of the central uplift of Martin Crater in western Thaumasia Planum, Mars, reveals highly folded and fractured geology throughout the 15-km diameter uplift. The stratigraphy in the central uplift of the crater has been rotated to near vertical dip and imaged by high-definition cameras aboard the Mars Reconnaissance Orbiter (MRO). These unique factors allow individual geologic beds in Martin Crater to be studied and located across the length of the uplift. Bedding in Martin Crater primarily strikes SSE-NNW and dips near vertically. Many units are separated by a highly complex series of linear faults, creating megablocks of uplifted material. Faulting is dominantly left-slip in surface expression and strikes SW-NE, roughly perpendicular to bedding, and major fold axes plunge toward the SW. Coupled with infrared imagery of the ejecta blanket, which shows an "exclusion zone" northeast of the crater, these structural indicators provide strong support for a low-angle impactor (approximately 10-20°) originating from the northeast. Acoustic fluidization is the prevailing theoretical model put forth to explain complex crater uplift. The theory predicts that uplifted megablocks in craters are small, discrete, separated and highly randomized in orientation. However, megablocks in Martin Crater are tightly interlocked and often continuous in lithology across several kilometers. Thus, the model of acoustic fluidization, as it is currently formulated, does not appear to be supported by the structural evidence found in Martin Crater.

Late Pleistocene and Holocene uplift history of Cyprus: implications for active tectonics along the southern margin of the Anatolian microplate

USGS Publications Warehouse

Harrison, R.W.; Tsiolakis, E.; Stone, B.D.; Lord, A.; McGeehin, J.P.; Mahan, S.A.; Chirico, P.

2013-01-01

The nature of the southern margin of the Anatolian microplate during the Neogene is complex, controversial and fundamental in understanding active plate-margin tectonics and natural hazards in the Eastern Mediterranean region. Our investigation provides new insights into the Late Pleistocene uplift history of Cyprus and the Troodos Ophiolite. We provide isotopic (14C) and radiogenic (luminescence) dates of outcropping marine sediments in eastern Cyprus that identify periods of deposition during marine isotope stages (MIS) 3, 4, 5 and 6. Past sea-levels indicated by these deposits are c. 95±25 m higher in elevation than estimates of worldwide eustatic sea-level. An uplift rate of c. 1.8 mm/year and possibly as much as c. 4.1 mm/year in the past c. 26–40 ka is indicated. Holocene marine deposits also occur at elevations higher than those expected for past SL and suggest uplift rates of c. 1.2–2.1 mm/year. MIS-3 marine deposits that crop out in southern and western Cyprus indicate uniform island-wide uplift. We propose a model of tectonic wedging at a plate-bounding restraining bend as a mechanism for Late Pleistocene to Holocene uplift of Cyprus; uplift is accommodated by deformation and seismicity along the margins of the Troodos Ophiolite and re-activation of its low-angle, basal shear zone.

Spatial and temporal variation of Cenozoic surface elevation in the Great Basin and Sierra Nevada

USGS Publications Warehouse

Horton, T.W.; Sjostrom, D.J.; Abruzzese, M.J.; Poage, M.A.; Waldbauer, J.R.; Hren, M.; Wooden, J.; Chamberlain, C.P.

2004-01-01

The surface uplift of mountain belts caused by tectonism plays an important role in determining the long-term climate evolution of the Earth. However, the general lack of information on the paleotopography of mountain belts limits our ability to identify the links and feedbacks between topography, tectonics, and climate change on geologic time-scales. Here, we present a ??18O and ??D record of authigenic minerals for the northern Great Basin that captures the timing and magnitude of regional surface uplift and subsidence events in the western United States during the Cenozoic. Authigenic calcite, smectite, and chert ??18O values suggest the northern Great Basin region experienced ???2km of surface uplift between the middle Eocene and early Oligocene followed by ???1 to 2km of surface subsidence in the southern Great Basin and/or Sierra Nevada since the middle Miocene. These data when combined with previously published work show that the surface uplift history varied in both space and time. Surface uplift migrated from north to south with high elevations in southern British Columbia and northeastern Washington in the middle Eocene and development of surface uplift in north and central Nevada in the Oligocene. This pattern of north to south surface uplift is similar to the timing of magmatism in the western Cordillera, a result that supports tectonic models linking magamtism with removal of mantle lithosphere and/or a subducting slab.

In vitro decomposition of Sphagnum by some microfungi resembles white rot of wood.

PubMed

Rice, Adrianne V; Tsuneda, Akihiko; Currah, Randolph S

2006-06-01

The abilities of some ascomycetes (Myxotrichaceae) from a Sphagnum bog in Alberta to degrade cellulose, phenolics, and Sphagnum tissue were compared with those of two basidiomycetes. Most Myxotrichaceae degraded cellulose and tannic acid, and removed cell-wall components simultaneously from Sphagnum tissues, whereas the basidiomycetes degraded cellulose and insoluble phenolics, and preferentially removed the polyphenolic matrix from Sphagnum cell walls. Mass losses from Sphagnum varied from up to 50% for some ascomycetes to a maximum of 35% for the basidiomycetes. The decomposition of Sphagnum by the Myxotrichaceae was analogous to the white rot of wood and indicates that these fungi have the potential to cause significant mineralization of carbon in bogs.

Uplift of the Kenai Peninsula, Alaska, since the 1964 Prince William Sound earthquake

NASA Technical Reports Server (NTRS)

Cohen, Steven; Holdahl, Sandford; Caprette, Douglas; Hilla, Stephen; Safford, Robert; Schultz, Donald

1995-01-01

Using Global Positioning System (GPS) receivers, we reoccupied several leveling benchmarks on the Kenai Peninsula of Alaska which had been surveyed by conventional leveling immediately following the March 27, 1964, Prince William Sound earthquake (M(sub w) = 9.3). By combining the two sets of measurements with a new, high-resolution model of the geoid in the region, we were able to determine the cumulative 1993-1964 postseismic vertical displacement. We find uplift at all of our benchmarks, relative to Seward, Alaska, a point that is stable according to tide gauge data. The maximum uplift of about 1 m occurs near the middle of the peninsula. The region of maximum uplift appears to be shifted northwest relative to the point of maximum coseismic subsidence. If we use tide gauge data at Nikishka and Seward to constrain the vertical motion, then the observed uplift has a trenchward tilt (down to the southeast) as well as an arching component. To explain the observations, we use creep-at-depth models. Most acceptable models require a fault slip of about 2.75 m, although this result is not unique. If the slip has been continuous since the 1964 earthquake, then the average slip rate is nearly 100 mm/yr, twice the plate convergence rate. Comparing the net uplift achieved in 29 years with that observed over 11 years in an adjacent region southeast of Anchorage, Alaska, we conclude that the rate of uplift is decreasing. A further decrease in the uplift rate is expected as the 29-year averaged displacement rate is about twice the plate convergence rate and therefore cannot be sustained over the entire earthquake cycle.

The distribution and tectonic framework of Late Paleozoic volcanoes in the Junggar basin and its adjacent area, NW China

NASA Astrophysics Data System (ADS)

Mao, X.; Li, J. H.

2012-04-01

We analyse the distribution and characteristics of 145 late Paleozoic volcanoes in north Xinjiang, NW China, including 32 volcanoes on the edge of the Junggar basin. These volcanoes are clustered and can be divided into calderas, volcanic domes, and volcanic necks. There are also 85 volcanoes inside the Junggar basin, which are dominantly distributed in the Ke-Bai fractured zone of the northwestern margin of Junggar Basin, 4 depressions (Dongdaohaizi Depression, Dishuiquan Depression, Sannan Depression and Wucaiwan Depression) and 7 uplifts (Baijiahai uplift, Beisantai uplift, Dibei uplift, Dinan uplift, Sangequan uplift, Shixi uplift and Xiayan uplift). The volcanoes inside the basin are principally controlled by Hercynian Fault Systems, along NE and nearly EW trending faults and most developed in the interjunctions of the faults. The long modification by late-stage weathering and leaching made the volcanoes difficult to identify. Remaining volcanic landforms, changing trends of the volcanic lithofacies and the typical volcanic rock, such as the crypto- explosive breccia, are the typical marks of the late Paleozoic volcanoes in the field; and the concealed volcanic edifices are identified by the techniques of seismic identification, such as seismic slicing, analysis of the attribute and tectonic trend plane. The ages of the volcanic rocks are focused on from 340 Ma to 320Ma and from 300 Ma to 295 Ma, corresponding to the subducting periods of West Junggar and East Junggar. From early Carboniferous to late Carboniferous, the volcanic activities in Junggar Basin and its adjacent areas show a variation trend from undersea to continental, from deep water to shallow water and from continental margin to intracontinental.

Radiogenic isotopes of arc lavas constrain uplift of the Andes

NASA Astrophysics Data System (ADS)

Scott, Erin; Allen, Mark B.; Macpherson, Colin; McCaffrey, Ken; Davidson, Jon; Saville, Christopher

2017-04-01

Orogenic plateaux are an ultimate expression of continental tectonics, but the timings and mechanisms of their formation are far from understood. The elevation history of the Andes is of particular importance for climatic reconstructions, as they pose the only barrier to atmospheric circulation in the Southern Hemisphere. Many varied techniques have been utilized over the last two decades to constrain Andean Plateau (AP) surface uplift. Two conflicting schools of thought are prominent: (1) recent, rapid rise since 10-6 Ma (Late Miocene), and (2) slow, continued uplift from 40 Ma. We propose a new, independent, approach to constrain AP surface uplift through time. By comparing isotopic compositions of Andean Quaternary arc lavas to present day crustal thickness and topography, we show that Sr and Nd isotopes are effective discriminants for the modern extent of the AP. As previously described, these isotopic systems are sensitive to crustal contamination, which in turn relates to crustal thickness, and, via isostasy, to regional surface elevation. We apply this relationship to a new compilation of published, age corrected, isotopic compositions of arc lavas, to constrain the surface uplift history of the Andes from the Jurassic to present day. Our results are consistent with significant AP surface uplift beginning in the Mid to Late Paleogene. We show that by 23 Ma, the AP was established at close to its modern elevations between at least 16-28 deg. S, thereby predating models for Late Miocene surface uplift. Between 23-10 Ma, surface uplift propagated south of 28 deg. S by a further 400 km. Our model has implications for understanding magma plumbing systems in regions of thick, wide crust, especially other orogenic plateaux.

GPS Imaging of Sierra Nevada Uplift

NASA Astrophysics Data System (ADS)

Hammond, W. C.; Blewitt, G.; Kreemer, C.

2015-12-01

Recent improvements in the scope and precision of GPS networks across California and Nevada have allowed for uplift of the Sierra Nevada to be observed directly. Much of the signal, in the range of 1 to 2 mm/yr, has been attributed to lithospheric scale rebound following massive groundwater withdrawal in the San Joaquin Valley in southern California, exacerbated by drought since 2011. However, natural tectonic deformation associated with long term uplift of the range may also contribute to the observed signal. We have developed new algorithms that enhance the signal of Sierra Nevada uplift and improve our ability to interpret and separate natural tectonic signals from anthropogenic contributions. We apply our new Median Interannual Difference Adjusted for Skewness (MIDAS) algorithm to the vertical times series and a inverse distance-weighted median spatial filtering and Delaunay-based interpolation to despeckle the rate map. The resulting spatially continuous vertical rate field is insensitive to outliers and steps in the GPS time series, and omits isolated features attributable to unstable stations or unrepresentative rates. The resulting vertical rate field for California and Nevada exhibits regionally coherent signals from the earthquake cycle including interseismic strain accumulation in Cascadia, postseismic relaxation of the mantle from recent large earthquakes in central Nevada and southern California, groundwater loading changes, and tectonic uplift of the Sierra Nevada and Coast Ranges. Uplift of the Sierra Nevada extends from the Garlock Fault in the south to an indefinite boundary in the north near the latitude of Mt. Lassen to the eastern Sierra Nevada range front in Owen's Valley. The rates transition to near zero in the southern Walker Lane. The eastern boundary of uplift coincides with the highest strain rates in the western Great Basin, suggesting higher normal fault slip rates and a component of tectonic uplift of the Sierra Nevada.

Uplifting Behavior of Shallow Buried Pipe in Liquefiable Soil by Dynamic Centrifuge Test

PubMed Central

Liu, Jingwen; Ling, Daosheng

2014-01-01

Underground pipelines are widely applied in the so-called lifeline engineerings. It shows according to seismic surveys that the damage from soil liquefaction to underground pipelines was the most serious, whose failures were mainly in the form of pipeline uplifting. In the present study, dynamic centrifuge model tests were conducted to study the uplifting behaviors of shallow-buried pipeline subjected to seismic vibration in liquefied sites. The uplifting mechanism was discussed through the responses of the pore water pressure and earth pressure around the pipeline. Additionally, the analysis of force, which the pipeline was subjected to before and during vibration, was introduced and proved to be reasonable by the comparison of the measured and the calculated results. The uplifting behavior of pipe is the combination effects of multiple forces, and is highly dependent on the excess pore pressure. PMID:25121140

Ice cap melting and low-viscosity crustal root explain the narrow geodetic uplift of the Western Alps

NASA Astrophysics Data System (ADS)

Chéry, J.; Genti, M.; Vernant, P.

2016-04-01

More than 10 years of geodetic measurements demonstrate an uplift rate of 1-3 mm/yr of the high topography region of the Western Alps. By contrast, no significant horizontal motion has been detected. Two uplift mechanisms have been proposed: (1) the isostatic response to denudation responsible for only a fraction of the observed uplift and (2) the rebound induced by the Wurmian ice cap melting which predicts a broader uplifting region than the one evidenced by geodetic observations. Using a numerical model to fit the geodetic data, we show that a crustal viscosity contrast between the foreland and the central part of the Alps, the latter being weaker with a viscosity of 1021 Pa s, is needed. The vertical rates are enhanced if the strong uppermost mantle beneath the Moho is interrupted across the Alps, therefore allowing a weak vertical rheological anomaly over the entire lithosphere.

Effects of long-term drainage on microbial community composition vary between peatland types

NASA Astrophysics Data System (ADS)

Urbanová, Zuzana; Barta, Jiri

2016-04-01

Peatlands represent an important reservoir of carbon, but their functioning can be threatened by water level drawdown caused by climate or land use change. Knowledge of how microbial communities respond to long-term drainage in different peatland types could help improve predictions of the effect of climate change on these ecosystems. We investigated the effect of long-term drainage on microbial community composition in bog, fen and spruce swamp forests (SSF) in the Sumava Mountains (Czech Republic), using high-throughput barcoded sequencing, in relation to peat biochemical properties. Longterm drainage had substantial effects, which depended strongly on peatland type, on peat biochemical properties and microbial community composition. The effect of drainage was most apparent on fen, followed by SSF, and lowest on bog. Long-term drainage led to lower pH, reduced peat decomposability and increased bulk density, which was reflected by reduced microbial activity. Bacterial diversity decreased and Acidobacteria became the dominant phylum on drained sites, reflecting a convergence in bacterial community composition across peatlands after long-term drainage. The archaeal communities changed very strongly and became similar across drained peatlands. Overall, the characteristic differences between distinct peatland types under natural conditions were diminished by long-term drainage. Bog represented a relatively resilient system while fen seemed to be very sensitive to environmental changes.

Features of seasonal temperature variations in peat soils of oligotrophic bogs in south taiga of Western Siberia

NASA Astrophysics Data System (ADS)

Kiselev, M. V.; Dyukarev, E. A.; Voropay, N. N.

2018-03-01

The work presents the results of the study of the peculiarities of the temperature regime in the five basic ecosystems of oligotrophic bogs in the south taiga zone of Western Siberia in 2011-2016. The soil temperature regime was studied using the atmospheric-soil measuring complex at different depths from surface down to 240 cm. All sites were divided into two groups according to the bog water level: flooded sites (hollow and open fen) and drained sites (ridge, tall and low ryam). The waterlogged sites are better warmed in the summer period and slowly freeze in the winter period. The analysis of the annual cycle of temperature showed that the maximum surface temperature is in July. The minimum temperature on the surface is observed in February or January. The greatest temperature gradient was recorded in the upper 2 cm layer. The gradient at the open fen was -2 °C/cm in February and 1.1 °C/cm in October. The peak of formation of the seasonally frozen layer occurs at the end of autumn or in the beginning of winter. The degradation of the seasonally frozen layer was observed both from top and bottom, but the degradation rate from the top is faster.

Ebullition, Plant-Mediated Transport, and Subsurface Horizontal Water Flow Dominate Methane Transport in an Arctic Sphagnum Bog

NASA Astrophysics Data System (ADS)

Wehr, R. A.; McCalley, C. K.; Logan, T. A.; Chanton, J.; Crill, P. M.; Rich, V. I.; Saleska, S. R.

2017-12-01

Emission of the greenhouse gas methane from wetlands is of prime concern in the prediction of climate change - especially emission associated with thawing permafrost, which may drive a positive feedback loop of emission and warming. In addition to the biochemistry of methane production and consumption, wetland methane emission depends critically on the transport mechanisms by which methane moves through and out of the ecosystem. We therefore developed a model of methane biochemistry and transport for a sphagnum bog representing an intermediate permafrost thaw stage in Stordalen Mire, Sweden. In order to simultaneously reproduce measured profiles of both the concentrations and isotopic compositions of both methane and carbon dioxide in the peat pore water (Fig. 1) - as well as the surface methane emission - it was necessary for the model to include ebullition, plant-mediated transport via aerenchyma, and subsurface horizontal water flow. Diffusion of gas through the pore water was relatively unimportant. As a result, 90% of the produced methane escaped the wetland rather than being consumed by methanotrophic organisms in the near-surface pore water. Our model provides a comprehensive picture of methane emission from this bog site by quantifying the vertical profiles of: acetoclastic methanogenesis, hydrogenotrophic methanogenesis, methane oxidation, aerobic respiration, ebullition, plant-mediated transport, subsurface horizontal water flow, and diffusion.

Antioxidant properties, phenolic composition and potentiometric sensor array evaluation of commercial and new blueberry (Vaccinium corymbosum) and bog blueberry (Vaccinium uliginosum) genotypes.

PubMed

Kraujalytė, Vilma; Venskutonis, Petras Rimantas; Pukalskas, Audrius; Česonienė, Laima; Daubaras, Remigijus

2015-12-01

Antioxidant properties of juices of newly bred and known blueberry (Vaccinium corymbosum) genotypes and wild bog blueberry (Vaccinium uliginosum) were evaluated by ABTS(+) scavenging capacity (RSC), ferric reducing antioxidant power (FRAP), oxygen radical absorbance capacity (ORAC), total phenolic content (TPC) and total anthocyanin content (TAC) assays. TPC varied in the range of 0.85-2.81 mg gallic acid equiv./mL, RSC, FRAP and ORAC values were 6.38-20.9, 3.07-17.8 and 4.21-45.68 μmol Trolox equiv./g, respectively. New blueberry genotypes and bog blueberry demonstrated stronger antioxidant properties and TAC than other studied genotypes. The content of quinic (203-3614 μg/mL), chlorogenic (20.0-346.8 μg/mL) acids and rutin (0.00-26.88 μg/mL) measured by UPLC/ESI-QTOF-MS varied depending on the genotype. Juices were evaluated by electronic tongue; PCA score plot showed that the method discriminates different genotypes although some juice samples were located very closely and overlapping. Significant differences were observed between L(∗), a(∗), b(∗) colour parameters of some genotypes. Copyright © 2015 Elsevier Ltd. All rights reserved.

Decreasing concentrations of metals in Sphagnum mosses in ombrotrophic mires of the Sudety mountains (SW Poland) since late 1980s.

PubMed

Wojtuń, Bronisław; Samecka-Cymerman, Aleksandra; Kolon, Krzysztof; Kempers, Alexander J

2013-06-01

In this investigation we focus on the evaluation of changes in metal pollution between 1986 until 2011 by Sphagnum species as bioindicators in 100 km part of the Sudety mountains influenced by the former Black Triangle Region. Concentrations of Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn were measured in various Sphagnum species all from ombrotrophic bogs in the Sudety mountains (SW Poland). The tested hypothesis was that overall improvements in pollution control in the former Black Triangle Region between 1986 until recent reduced the amount of metals deposited and accumulated by these plants. Concentrations of Cd, Cr, Cu, Fe, Pb and Zn in Sphagnum species were very high in 1986 indicating a heavy pollution of the examined bogs in this period, and significantly higher than in samples collected in 2011. The PCCA ordination showed the similar pattern in all bogs. In 2011 concentration of the Co was significantly higher in hollow species and concentration of Mn was significantly higher in those from hummocks. Differences between hollow/hummock sites were more important than species-specific abilities of Sphagnum mosses to accumulate metals. Species from hollows were better bioindicators of Co and those from hummocks were better bioindicators of Mn pollution. Copyright © 2012 Elsevier Ltd. All rights reserved.

Flourish or flush: effects of simulated extreme rainfall events on Sphagnum-dwelling testate amoebae in a subarctic bog (Abisko, Sweden).

PubMed

Tsyganov, Andrey N; Keuper, Frida; Aerts, Rien; Beyens, Louis

2013-01-01

Extreme precipitation events are recognised as important drivers of ecosystem responses to climate change and can considerably affect high-latitude ombrotrophic bogs. Therefore, understanding the relationships between increased rainfall and the biotic components of these ecosystems is necessary for an estimation of climate change impacts. We studied overall effects of increased magnitude, intensity and frequency of rainfall on assemblages of Sphagnum-dwelling testate amoebae in a field climate manipulation experiment located in a relatively dry subarctic bog (Abisko, Sweden). The effects of the treatment were estimated using abundance, species diversity and structure of living and empty shell assemblages of testate amoebae in living and decaying layers of Sphagnum. Our results show that increased rainfall reduced the mean abundance and species richness of living testate amoebae. Besides, the treatment affected species structure of both living and empty shell assemblages, reducing proportions of hydrophilous species. The effects are counterintuitive as increased precipitation-related substrate moisture was expected to have opposite effects on testate amoeba assemblages in relatively dry biotopes. Therefore, we conclude that other rainfall-related factors such as increased infiltration rates and frequency of environmental disturbances can also affect testate amoeba assemblages in Sphagnum and that hydrophilous species are particularly sensitive to variation in these environmental variables.

Simulation of the hydrogeologic effects of oil-shale mining on the neighbouring wetland water balance: case study in north-eastern Estonia

NASA Astrophysics Data System (ADS)

Marandi, Andres; Karro, Enn; Polikarpus, Maile; Jõeleht, Argo; Kohv, Marko; Hang, Tiit; Hiiemaa, Helen

2013-11-01

The water balance of wetlands plays an integral role in their function. Developments adjacent to wetlands can affect their water balance through impacts on groundwater flow and increased discharge in the area, and they can cause lowering of the wetland water table. A 430 km2 area was selected for groundwater modelling to asses the effect of underground mining on the water balance of wetlands in north-eastern Estonia. A nature conservation area (encompassing Selisoo bog) is within 3 km of an underground oil-shale mine. Two future mining scenarios with different areal extents of mining were modeled and compared to the present situation. Results show that the vertical hydraulic conductivity of the subsurface is of critical importance to potential wetland dewatering as a result of mining. Significant impact on the Selisoo bog water balance will be caused by the approaching mine but there will be only minor additional impacts from mining directly below the bog. The major impact will arise before that stage, when the underground mine extension reaches the border of the nature conservation area; since the restriction of activities in this area relates to the ground surface, the conservation area’s border is not sufficiently protective in relation to underground development.

The influence of avian biovectors on mercury speciation in a bog ecosystem.

PubMed

Kickbush, Jocelyn C; Mallory, Mark L; Murimboh, John D; Rand, Jennie; Klapstein, Sara J; Loder, Amanda L; Hill, Nicholas M; O'Driscoll, Nelson J

2018-05-08

Methylmercury (MeHg) is a neurotoxin and endocrine disruptor that bioaccumulates and biomagnifies through trophic levels, resulting in potentially hazardous concentrations. Although wetlands are known hotspots for mercury (Hg) methylation, the effects of avian biovectors on these processes are poorly understood. We examined Hg speciation and distribution in shallow groundwater and surface water from a raised-bog with over 30years of avian biovector (herring gulls Larus argentatus and great black-backed gulls Larus marinus) colonization and guano input. Compared to the reference site, the avian-impacted bog had elevated concentrations of total dissolved organic carbon (TOC), total Hg, MeHg, phosphate (PO 4 3- ), and other trace metals, notably Pb, As, Cd and Ni. Spatial interpolation showed that the densest area of gull nesting was co-located with areas that had the highest concentrations of PO 4 3- , MeHg, As and Cd, but not total mercury (THg), and models suggested that Mn, PO 4 3- , and dissolved TOC were strong predictors of MeHg. Our findings suggest that while these gulls may not be a significant source of Hg, the excess of PO 4 3- (a well recognised component of guano) and the subsequent changes in water chemistry due to avian biovector subsidies may increase net Hg methylation. Copyright © 2018 Elsevier B.V. All rights reserved.

How Does Tree Density Affect Water Loss of Peatlands? A Mesocosm Experiment

PubMed Central

Limpens, Juul; Holmgren, Milena; Jacobs, Cor M. J.; Van der Zee, Sjoerd E. A. T. M.; Karofeld, Edgar; Berendse, Frank

2014-01-01

Raised bogs have accumulated more atmospheric carbon than any other terrestrial ecosystem on Earth. Climate-induced expansion of trees and shrubs may turn these ecosystems from net carbon sinks into sources when associated with reduced water tables. Increasing water loss through tree evapotranspiration could potentially deepen water tables, thus stimulating peat decomposition and carbon release. Bridging the gap between modelling and field studies, we conducted a three-year mesocosm experiment subjecting natural bog vegetation to three birch tree densities, and studied the changes in subsurface temperature, water balance components, leaf area index and vegetation composition. We found the deepest water table in mesocosms with low tree density. Mesocosms with high tree density remained wettest (i.e. highest water tables) whereas the control treatment without trees had intermediate water tables. These differences are attributed mostly to differences in evapotranspiration. Although our mesocosm results cannot be directly scaled up to ecosystem level, the systematic effect of tree density suggests that as bogs become colonized by trees, the effect of trees on ecosystem water loss changes with time, with tree transpiration effects of drying becoming increasingly offset by shading effects during the later phases of tree encroachment. These density-dependent effects of trees on water loss have important implications for the structure and functioning of peatbogs. PMID:24632565

Heat transport in the Red Lake Bog, Glacial Lake Agassiz Peatlands

USGS Publications Warehouse

McKenzie, J.M.; Siegel, D.I.; Rosenberry, D.O.; Glaser, P.H.; Voss, C.I.

2007-01-01

We report the results of an investigation on the processes controlling heat transport in peat under a large bog in the Glacial Lake Agassiz Peatlands. For 2 years, starting in July 1998, we recorded temperature at 12 depth intervals from 0 to 400 cm within a vertical peat profile at the crest of the bog at sub-daily intervals. We also recorded air temperature 1 m above the peat surface. We calculate a peat thermal conductivity of 0.5 W m-1 ??C-1 and model vertical heat transport through the peat using the SUTRA model. The model was calibrated to the first year of data, and then evaluated against the second year of collected heat data. The model results suggest that advective pore-water flow is not necessary to transport heat within the peat profile and most of the heat is transferred by thermal conduction alone in these waterlogged soils. In the spring season, a zero-curtain effect controls the transport of heat through shallow depths of the peat. Changes in local climate and the resulting changes in thermal transport still may cause non-linear feedbacks in methane emissions related to the generation of methane deeper within the peat profile as regional temperatures increase. Copyright ?? 2006 John Wiley & Sons, Ltd.

Holocene vegetation and climate change recorded in alpine bog sediments from the Borreguiles de la Virgen, Sierra Nevada, southern Spain

NASA Astrophysics Data System (ADS)

Jiménez-Moreno, Gonzalo; Anderson, R. Scott

2012-01-01

High-resolution pollen and magnetic susceptibility (MS) analyses have been carried out on a sediment core taken from a high-elevation alpine bog area located in Sierra Nevada, southern Spain. The earliest part of the record, from 8200 to about 7000 cal yr BP, is characterized by the highest abundance of arboreal pollen and Pediastrum, indicating the warmest and wettest conditions in the area at that time. The pollen record shows a progressive aridification since 7000 cal yr BP that occurred in two steps, first shown by a decrease in Pinus, replaced by Poaceae from 7000 to 4600 cal yr BP and then by Cyperaceae, Artemisia and Amaranthaceae from 4600 to 1200 cal yr BP. Pediastrum also decreased progressively and totally disappeared at ca. 3000 yr ago. The progressive aridification is punctuated by periodically enhanced drought at ca. 6500, 5200 and 4000 cal yr BP that coincide in timing and duration with well-known dry events in the Mediterranean and other areas. Since 1200 cal yr BP, several changes are observed in the vegetation that probably indicate the high-impact of humans in the Sierra Nevada, with pasturing leading to nutrient enrichment and eutrophication of the bog, Pinus reforestation and Olea cultivation at lower elevations.

Vulnerability of the peatland carbon sink to sea-level rise

NASA Astrophysics Data System (ADS)

Whittle, Alex; Gallego-Sala, Angela V.

2016-06-01

Freshwater peatlands are carbon accumulating ecosystems where primary production exceeds organic matter decomposition rates in the soil, and therefore perform an important sink function in global carbon cycling. Typical peatland plant and microbial communities are adapted to the waterlogged, often acidic and low nutrient conditions that characterise them. Peatlands in coastal locations receive inputs of oceanic base cations that shift conditions from the environmental optimum of these communities altering the carbon balance. Blanket bogs are one such type of peatlands occurring in hyperoceanic regions. Using a blanket bog to coastal marsh transect in Northwest Scotland we assess the impacts of salt intrusion on carbon accumulation rates. A threshold concentration of salt input, caused by inundation, exists corresponding to rapid acidophilic to halophilic plant community change and a carbon accumulation decline. For the first time, we map areas of blanket bog vulnerable to sea-level rise, estimating that this equates to ~7.4% of the total extent and a 0.22 Tg yr-1 carbon sink. Globally, tropical peatlands face the proportionally greatest risk with ~61,000 km2 (~16.6% of total) lying ≤5 m elevation. In total an estimated 20.2 ± 2.5 GtC is stored in peatlands ≤5 m above sea level, which are potentially vulnerable to inundation.

Permanent uplift in magmatic systems with application to the Tharsis region of Mars

NASA Astrophysics Data System (ADS)

Phillips, R. J.; Sleep, N. H.; Banerdt, W. B.

1990-04-01

A model is derived for predicting both crustal displacement (leading to permanent uplift) and topographic elevation in regional large-scale magmatic systems associated with partial melting of mantle rocks. The model is then applied to the Tharsis region of Mars to test the uplift versus construction. It was found that a lower bound estimate of the fraction of intrusives necessary for any uplift at all is about 85 percent of the total magmatic products at Tharsis. Thus, it is proposed that most of the magmas associated with Tharsis evolution ended up as intrusive bodies in the crust and upper mantle.

Uplift in the Fiordland region, New Zealand: implications for incipient subduction.

PubMed

House, M A; Gurnis, M; Kamp, P J J; Sutherland, R

2002-09-20

Low-temperature thermochronometry reveals regional Late Cenozoic denudation in Fiordland, New Zealand, consistent with geodynamic models showing uplift of the overriding plate during incipient subduction. The data show a northward progression of exhumation in response to northward migration of the initiation of subduction. The locus of most recent uplift coincides with a large positive Bouguer gravity anomaly within Fiordland. Thermochronometrically deduced crustal thinning, anomalous gravity, and estimates of surface uplift are all consistent with approximately 2 kilometers of dynamic support. This amount of dynamic support is in accord with geodynamic predictions, suggesting that we have dated the initiation of subduction adjacent to Fiordland.

An assessment of the accuracy of the geodetic measurements that define the southern California uplift.

USGS Publications Warehouse

Mark, R.K.; Tinsley, J. C.; Newman, E.B.; Gilmore, T.D.; Castle, R.O.

1981-01-01

Examination of the charge that the geodetic measurements which define the southern California uplift are seriously flawed by height-dependent systematic errors indicates that this charge is unfounded. Comparisons between the results of measurements in which the correlation between topography and signal is generally poor reveal large aseismic tilts in a number of places within and around the margins of the uplift. Especially significant in this context are the results of preuplift and postuplift levellings over routes characterized by diverse length, topography, and atmospheric conditions that produce closely matching, temporally equivalent heights for a representative bench mark within the uplift.-from Authors

Permanent uplift in magmatic systems with application to the Tharsis region of Mars

NASA Technical Reports Server (NTRS)

Phillips, Roger J.; Sleep, Norman H.; Banerdt, W. Bruce

1990-01-01

A model is derived for predicting both crustal displacement (leading to permanent uplift) and topographic elevation in regional large-scale magmatic systems associated with partial melting of mantle rocks. The model is then applied to the Tharsis region of Mars to test the uplift versus construction. It was found that a lower bound estimate of the fraction of intrusives necessary for any uplift at all is about 85 percent of the total magmatic products at Tharsis. Thus, it is proposed that most of the magmas associated with Tharsis evolution ended up as intrusive bodies in the crust and upper mantle.

Colorado Plateau magmatism and uplift by warming of heterogeneous lithosphere.

PubMed

Roy, Mousumi; Jordan, Thomas H; Pederson, Joel

2009-06-18

The forces that drove rock uplift of the low-relief, high-elevation, tectonically stable Colorado Plateau are the subject of long-standing debate. While the adjacent Basin and Range province and Rio Grande rift province underwent Cenozoic shortening followed by extension, the plateau experienced approximately 2 km of rock uplift without significant internal deformation. Here we propose that warming of the thicker, more iron-depleted Colorado Plateau lithosphere over 35-40 Myr following mid-Cenozoic removal of the Farallon plate from beneath North America is the primary mechanism driving rock uplift. In our model, conductive re-equilibration not only explains the rock uplift of the plateau, but also provides a robust geodynamic interpretation of observed contrasts between the Colorado Plateau margins and the plateau interior. In particular, the model matches the encroachment of Cenozoic magmatism from the margins towards the plateau interior at rates of 3-6 km Myr(-1) and is consistent with lower seismic velocities and more negative Bouguer gravity at the margins than in the plateau interior. We suggest that warming of heterogeneous lithosphere is a powerful mechanism for driving epeirogenic rock uplift of the Colorado Plateau and may be of general importance in plate-interior settings.

Use of TOPSAR digital elevation data to determine the 3-dimensional shape of an alluvial fan

NASA Technical Reports Server (NTRS)

Farr, Tom G.

1995-01-01

Landforms in arid regions record the interplay between tectonic forces and climate. Alluvial fans are a common landform in desert regions where the rate of uplift is greater than weathering or sedimentation. Changes in uplift rate or climatic conditions can lead to isolation of the currently forming fan surface through entrenchment and construction of another fan either further from the mountain front (decreased uplift or increased runoff) or closer to the mountain front (increased uplift or decreased runoff). Thus, many alluvial fans are made up of a mosaic of fan units of different age, some older than 1 million years. For this reason, determination of the stages of fan evolution can lead to a history of uplift and runoff. In an attempt to separate the effects of tectonic (uplift) and climatic (weathering, runoff, sedimentation) processes on the shapes of alluvial fan units, a modified conic equation developed by Troeh (1965) was fitted to TOPSAR digital topographic data for the Trail Canyon alluvial fan in Death Valley, California. This allows parameters for the apex position, slope, and radial curvature to be compared with unit age.

The Sedimentary History of Southern Central Crete: Implications for Neogene Uplift

NASA Astrophysics Data System (ADS)

Kröger, K.; Brachert, T. C.; Reuter, M.

2003-04-01

The tectonic setting of Crete was largely extensional since Lower Miocene uplift and exhumation of HP/LT rocks. Erosion of uplifted areas resulted in the deposition of terrestrial to marine sediments in the Messara and Iraclion Basins. There are several concurring models that discuss Late Neogene uplift of the basinal margins. Neogene near shore sediments in the south of the Messara Basin record fault movements contemporaneous to sedimentation and sedimentary input from the hinterland. Therefore they provide information on the paleogeographic situation and the resulting amount of subsidence and uplift of mountain areas since the Upper Miocene. The studied sediments consist of terrestrial to shallow marine, floodplain related sediments of the Upper Miocene Ambelouzos Formation that are overlain by platform limestones of the Upper Miocene Varvara Formation. In the Messara Basin these units are overlain by the Pliocene Kourtes Formation. The stratigraphic architecture of these deposits indicates fragmentation of the basinal margin. Proximal boulder conglomerates and reworked blocks of the Ambelouzos formation indicate fault activity during the deposition of the Varvara Formation. Contents of terrigenous clastics, provided by rivers and distributed by longshore currents, are high in the Ambelouzos and the lower Varvara Formations but decrease rapidly upsection within the Varvara Formation. This indicates drowning of the fault bounded blocks and little topography of the hinterland (Asteroussia Mountains) at that time. The Pliocene marls at the southern margin of the Messara Basin contain lithoclasts of the Upper Miocene limestones and thus indicate uplift of the carbonate platform. The modern topographic elevation of formerly drowned fault bounded blocks requires a minimum uplift of 400m. Main uplift occurred at approximately orthogonal NW-SE and SW-NE striking normal to oblique faults. The present elevation of the Asteroussia Mountains indicates net uplift of at least 1000m since the Early Pliocene. At the Central Iraklion Ridge that separates the Messara and Iraclion Basins a similar history is indicated for the Psiloritis Mountains by fault movements within Neogene near shore sediments and their subsequent drowning. A structural model of the Neogene evolution of Crete therefore has to explain successive phases of uplift and subsidence in an over all extensional setting only slightly oblique to the modern direction of convergence between Africa and the Aegean microplate.

Forearc Morphotectonics and Megathrust Earthquakes Along the Middle America Convergent Margin, Nicoya Peninsula, Costa Rica

NASA Astrophysics Data System (ADS)

Marshall, J. S.; Spotila, J. A.; Gardner, T.; Protti, M.; LaFromboise, E. J.; Morrish, S.; Robinson, M.; Barnhart, A.; Butcher, A.; Khaw, F.; Piestrzeniewicz, P.; Ritzinger, B.; Utick, J.; Wellington, K.

2015-12-01

The Nicoya Peninsula, Costa Rica forms a prominent morphologic high along the Middle America forearc where the Cocos plate subducts beneath the Caribbean plate at 8.5 cm/yr. This emergent coastal landmass lies directly above the megathrust along a seismogenic zone that produces frequent major earthquakes. Along the Nicoya coast, Quaternary marine and fluvial terraces record net uplift in a pattern that shadows the peninsula's overall topographic form. Terrace mapping, surveying, and age dating (14C, OSL, TCN) reveal uplift variations that coincide with three contrasting domains of subducting seafloor (EPR, CNS-1, CNS-2). Uplift rates vary between 0.1-0.2 m/ky inboard of older EPR crust in the north; 0.2-0.5 m/ky inboard of younger CNS-1 crust along the central coast; and 1.5-2.5 m/ky inboard of CNS-2 seamounts impacting the peninsula's southern tip. GIS digital terrain analysis reveals a deformation pattern consistent with field geomorphic and geologic observations. The two largest Nicoya earthquakes in the past century (1950 Mw7.8; 2012 Mw7.6) each generated decimeter-scale coseismic uplift along the central coast. The 2012 uplift pattern coincides with the area of pre-event locking, mainshock slip, prior 1950 rupture, and 1950 coseismic uplift. Most of the 1950 uplift was recovered by gradual interseismic subsidence during six decades of strain accumulation leading to the 2012 rupture. Paleoseismic sediment coring in Nicoya coastal wetlands reveals fragmentary stratigraphic evidence consistent with earlier Holocene earthquake induced changes in land level. While elastic strain accumulation and release produce short-term cycles of uplift and subsidence, long-term net uplift results in gradual coastal emergence and the growth of topographic relief. Net uplift along the central Nicoya segment may be the product of irrecoverable seismic cycle strain (shortening), coupled with tectonic erosion near the trench and subsequent underplating of eroded material at depth beneath the peninsula. Our results are consistent with geophysical observations that indicate along-strike segmentation of the Nicoya seismogenic zone and the presence of three principal source areas for large earthquakes: 1) Papagayo (1916, M>7.0), 2) Nicoya (1950, Mw7.8; 2012 Mw7.6), and 3) Cobano (1990 Mw7.3).

Coastal tectonics on the eastern margin of the Pacific Rim: Late Quaternary sea-level history and uplift rates, Channel Islands National Park, California, USA

USGS Publications Warehouse

Muhs, Daniel R.; Simmons, Kathleen R.; Schumann, R. Randall; Groves, Lindsey T.; DeVogel, Stephen B.; Minor, Scott A.; Laurel, Deanna

2014-01-01

The Pacific Rim is a region where tectonic processes play a significant role in coastal landscape evolution. Coastal California, on the eastern margin of the Pacific Rm, is very active tectonically and geomorphic expressions of this include uplifted marine terraces. There have been, however, conflicting estimates of the rate of late Quaternary uplift of marine terraces in coastal California, particularly for the orthern Channel Islands. In the present study, the terraces on San Miguel Island and Santa Rosa Island were mapped and new age estimates were generated using uranium-series dating of fossil corals and amino acid geochronology of fossil mollusks. Results indicate that the 2nd terrace on both islands is ~120 ka and the 1st terrace on Santa Rosa Island is ~80 ka. These ages correspond to two global high-sea stands of the Last Interglacial complex, marine isotope stages (MIS) 5.5 and 51, respectively. The age estimates indicate that San Miguel Island and Santa Rosa Island have been tectonically uplifted at rates of 0.12e0.20 m/ka in the late Quaternary, similar to uplift rates inferred from previous studies on neighboring San Cruz Island. The newly estimated uplift rates for the northern Channel Islands are, however, an order of magnitude lower than a recent study that generated uplift rates from an offshore terrace dating to the Last Glacial period. The differences between the estimated uplift rates in the present study and the offshore study are explained by the magnitude of glacial isostatic adjustment (GIA) effects that were not known at the time of the earlier study. Set in the larger context of northeastern Pacific Rim tectonics, Channel Islands uplift rates are higher than those coastal localities on the margin of the East Pacific Rise spreading center, but slightly lower than those of most localities adjacent to the Cascadia subduction zone. The uplift rates reported here for the northern Channel Islands are similar to those reported for most other localities where strike-slip tectonics are dominant, but lower than localities where restraining bends (such as the Big Bend of the San Andreas Fault) result in crustal shortening.

Patterns and average rates of late Neogene Recent uplift of the Betic Cordillera, SE Spain

NASA Astrophysics Data System (ADS)

Braga, Juan C.; Martín, José M.; Quesada, Cecilio

2003-02-01

The facies distribution in the sedimentary units infilling a series of Neogene basins has been used to reconstruct the relief generation and uplift across the Internal Zone of the Betic Cordillera in southern Spain. Uplift amounts and average rates can be estimated using the current elevation of the outcrops of well-dated deposits indicative of ancient sea-level positions. Coral reefs and coastal conglomerates record the initial development of emergent Betic relief during the Langhian. Continental and marginal marine deposits indicate the existence of a large island centred on the present Sierra Nevada-Sierra de los Filabres chain by the end of the Middle Miocene. The precursor of the Sierra Nevada-Sierra de los Filabres chain, originally part of this large island, remained emerged whilst the surrounding areas were re-invaded by the sea during the early Tortonian. At the end of the Tortonian the inland basins (Granada and Guadix basins) became continental, while the Sierras de la Contraviesa, Sierra de Gádor and Sierra Alhamilla emerged, separating the Alborán Basin from the Alpujarra, Tabernas and Sorbas basins, which became narrow passages of the Mediterranean Sea. In contrast, the Sierra Cabrera emerged during the late Messinian, suggesting a progressive uplift from west to east of the sierras south of the Sierra Nevada-Sierra de los Filabres chain. During the Pliocene, only the low areas closest to the present-day coast remained as marine basins and progressively emerged throughout this stage. The highest average uplift rate recorded is 280 m/Ma for the Sierra de Gádor, although the average uplift rates of upper-Neogene coastal marine rocks since depositon have maximum values of approximately 200 m/Ma. Most of the uplift of the Betic mountains took place before the early Pliocene. The recorded uplift of Neogene rocks was highest at the margins of western Sierra Nevada, where peaks higher than 3000 m occur. The average rates of uplift were lower to the east of this major relief. The main sierras and depressions in the present-day landscape correspond respectively to the emergent land, in which uplift was concentrated, and to the marine basins that existed before the final emergence of the region. The altitude of the sierras reflects the time at which they became emergent, the highest mountains being the first to rise above sea level.

Nutrient Addition Leads to a Weaker CO2 Sink and Higher CH4 Emissions through Vegetation-Microclimate Feedbacks at Mer Bleue Bog, Canada

NASA Astrophysics Data System (ADS)

Bubier, J. L.; Arnkil, S.; Humphreys, E.; Juutinen, S.; Larmola, T.; Moore, T. R.

2015-12-01

Atmospheric nitrogen (N) deposition has led to nutrient enrichment in wetlands globally, affecting plant community composition, carbon (C) cycling, and microbial dynamics. Nutrient-limited boreal bogs are long-term sinks of carbon dioxide (CO2), but sources of methane (CH4), an important greenhouse gas. We fertilized Mer Bleue Bog, a Sphagnum moss and evergreen shrub-dominated ombrotrophic bog near Ottawa, Ontario, for 10-15 years with N as NO3 and NH4 at 5, 10 and 20 times ambient N deposition (0.6-0.8 g N m-2 y-1), with and without phosphorus (P) and potassium (K). Treatments were applied to triplicate plots (3 x 3 m) from May - August 2000-2015 and control plots received distilled water. We measured net ecosystem CO2 exchange (NEE), ecosystem photosynthesis and respiration, and CH4 flux with climate-controlled chambers; leaf-level CO2 exchange and biochemistry; substrate-induced respiration, CH4 production and consumption potentials with laboratory incubations; plant species composition and abundance; and microclimate (peat temperature, moisture, light interception). After 15 years, we have found that NEE has decreased, and CH4 emissions have increased, in the highest nutrient treatments owing to changes in vegetation, microtopography, and peat characteristics. Vegetation changes include a loss of Sphagnum moss and introduction of new deciduous species. Simulated atmospheric N deposition has not benefitted the photosynthetic apparatus of the dominant evergreen shrubs, but resulted in higher foliar respiration, contributing to a weaker ecosystem CO2 sink. Loss of moss has led to wetter near-surface substrate, higher rates of decomposition and CH4 emission, and a shift in microbial communities. Thus, elevated atmospheric deposition of nutrients may endanger C storage in peatlands through a complex suite of feedbacks and interactions among vegetation, microclimate, and microbial communities.

Identification of runoff formation with two dyes in a mid-latitude mountain headwater

NASA Astrophysics Data System (ADS)

Vlcek, Lukas; Schneider, Philipp; Falatkova, Kristyna

2017-04-01

There have been numerous studies on subsurface flow in peat bog areas, as both water scarcity and floods have led to increased attention to this specific environment and its role within the hydrological cycle. In contrast, this experimental study identifies runoff formation at two opposite hillslopes in a peaty mountain headwater; a slope with organic soils (Peat / Histosol) and shallow groundwater ( 0.5 m below surface) complemented by a slope with mineral soils (Podzol) and no detectable groundwater within 2 m below surface. Differences in infiltration, percolation, and preferential flowpaths between both hillslopes could be identified by sprinkling experiments with two dyes - Brilliant Blue FCF and Fluorescein. By excavating dye-stained soil profiles parallel ("lateral") and perpendicular ("frontal") to the slopes' gradients - both within and downstream of the sprinkling plots - dye stained flow patterns in the soil could be clearly identified. The results show that biomat flow occurred at both hillslopes. The dye solutions infiltrated into the soil and continued either as lateral subsurface pipeflow (SSF), in the case of the Peat Bog, or percolated vertically towards the bedrock in the case of the Podzol. The study provides evidence that biomat flow (BMF) - shallow, lateral preferential flowpaths along decomposed tree roots or logs - is a major runoff formation process at the Peat Bog hillslope and in the adjacent riparian zone. This lateral flow through the organic soil hillslope (Peat Bog) towards the stream occurred mainly as shallow subsurface flow in organic layers above the groundwater level (BMF and SSF), but water partly percolates to the shallow groundwater via vertical macropores as well . In contrast, the mineral soil hillslope (Podzol) was mostly dominated by vertical percolation. Lateral flow occurred only on short distances in the organic topsoil as biomat flow (BMF). The sorptive tracer Brilliant Blue FCF successfully stained flowpaths in the soil at both hillslopes, whereas the identification of soil staining patterns by the relatively conservative tracer Fluorescein was limited on organic soil profiles.

Branched GDGT-based paleotemperature reconstruction of the last 30,000 years in humid monsoon region of Southeast China

NASA Astrophysics Data System (ADS)

Wang, M.

2017-12-01

The use of bacterial branched glycerol dialkyl glycerol tetraethers (brGDGTs) to reconstruct mean annual air temperatures (MAATs) and environmental pH from soils has sparked significant interest in the terrestrial paleoclimate community. However, the reconstruction of these climate proxies from peat bogs is rare in monsoonal regions of the East Asia. This research was carried out on a core from the Shuizhuyang (SZY) peat bog located in Fujian Province. Branched GDGT (brGDGT) indexes were used for reconstructing the paleoclimate of the last 30 cal ka. The aim was to evaluate quantitatively the MAAT and pH values since the Last Glacial Maximum (LGM) in the subtropical zone of China. Results show that the CBT-MBT'-derived MAAT at MIS 3 is about 15.6 °C on average, which is followed by a significant fall at the LGM (11.7-12.1 °C). The temperature difference between the LGM and the present-day value is as high as 5.8 °C. The synchronous variation of biomarker and pollen proxies indicates that replacement of subtropical evergreen broadleaved forests by coldtolerant, deciduous broadleaved forests was driven by the significant drop in air temperature. Our results also indicate that the Younger Dryas event lasted from about 12.9 to about 11.3 cal ka, and cooling event at 3.2 cal ka in the late Holocene was detected, showing the sensitivity of peat bogs to rapid cooling. Our pH reconstructions indicate that the pH of the bog rose during Heinrich 1 and Bølling-Allerød periods, probably due to low precipitation, and were lowest in the Holocene thermal maximum between 8 ka and 2.5 ka, probably due to higher precipitation. The decoupling of reconstructed MAAT and pH during particularly deglaciation and YD periods supports the hypothesis that the variations in temperature and precipitation are not always synchronous.

Factors Controlling Diffusive CO2 Transport and Production in the Cedarburg Bog, Saukville, Wisconsin

NASA Astrophysics Data System (ADS)

Joynt, E.; Grundl, T.; Han, W. S.; Gulbranson, E. L.

2016-12-01

Wetlands are vital components of the carbon cycle containing an estimated 20-30% of the global soil carbon store. The Cedarburg Bog of southeastern Wisconsin contains multiple wetland types, including the southernmost string bog found in North America. Carbon dioxide (CO2) behavior in wetland systems respond to multiple interdependent variables that are collectively not well understood. Modeling CO2 behavior in wetland environments requires a detailed representation of these variables. In 2014 a LI-COR 8100A automated soil gas flux system was installed in the string bog, measuring CO2 concentration and flux. Groundwater data, soil temperature, and weather data (temperature, pressure, precipitation, etc.) were included to reveal correlations between soil CO2 flux/concentration and external forces. In 2015 field data were complemented with soil moisture data and depth profiles of pore water chemistry and stable carbon isotopes from peat and soil gas to discern source and evolution of CO2 at depth. Initial gaseous δ13C(CO2) average -18‰ and deplete overnight suggesting increasing microbial metabolic efficiency. δ13C soil microbial biomass measure roughly -21‰ to -22‰. LI-COR data show diurnal and seasonal trends; CO2 concentration builds overnight while flux increases during the day. CO2 flux magnitude and CO2 concentration range peak in mid-summer, but frequency of increased CO2 flux events varies seasonally each year. Flux averages 7.55 mgCO2/min-m2 during the day but reaches 530 mgCO2/min-m2. Increased atmospheric and soil temperatures and decreasing atmospheric pressure prelude increasing CO2 flux intensity, though correlation strengths vary. Water level may influence CO2 flux, but observations suggest a mobile peat surface with the water table. 2016 imagery from trail cameras will determine extent of peat/well casing movement with water level changes. Further interpretation of data trends will utilize HYDRUS-1D to quantify relationships under changing environmental conditions.

Holocene climate variability in the western Mediterranean through a multiproxy analysis from Padul peat bog (Sierra Nevada, Spain)

NASA Astrophysics Data System (ADS)

Ramos-Román, María J.; Jiménez-Moreno, Gonzalo; Camuera, Jon; García-Alix, Antonio; Anderson, R. Scott; Jiménez-Espejo, Francisco J.; Sachse, Dirk

2017-04-01

The Iberian Peninsula, located in the Mediterranean area, is an interesting location for paleoclimate studies due to its geographic situation between arid and humid climates. Sediments from peat bogs and lakes from Sierra Nevada, in southeastern Iberian Peninsula, have been very informative in terms of how vegetation and wetland environments were impacted by Holocene climate change. These studies are essential if we want to understand the past climate change in the area, which is the key to identify the possible environmental response of the Sierra Nevada ecosystems to future climate scenarios. Padul basin, located in the southwest of the Sierra Nevada mountain range, contains a ca. 100 m-thick peat bog sedimentary sequence that was deposited during the past 1 Ma making this area interesting for paleoenvironmental and paleoclimatic reconstructions. A new 43 m-long sedimentary record has recently been retrieved from the Padul peat bog. In this study we have developed a multiproxy analysis of the Holocene part of the Padul-15-05 core including pollen analysis, XRF-core scanner, magnetic susceptibility and organic geochemistry, supported by an age control based on AMS radiocarbon dates, providing with information about vegetation and climate variability during the past 9.9 cal ka BP. This multiproxy reconstruction of the Padul-15-05 evidences the Mediterranean as a sensitive area with respect to global-scale climate system, showing relevant climate episodes such as the ca. 8, 7.5, 6.5 and 5.5 cal ka BP events during the early and middle Holocene. The trend to aridification to the late Holocene is interrupted by more arid and humid periods as the Iberian Roman Humid Period (from ca. 3 to 1.6 cal ka BP), the Dark Ages (from ca. 1.5 to 1.1 cal ka BP), the Medieval Climate Anomaly (from ca. 1.1 to 1.3 cal ka BP) and the Little Ice Age period (from ca. 500 to 100 cal yr BP).

Charring temperatures are driven by the fuel types burned in a peatland wildfire

PubMed Central

Hudspith, Victoria A.; Belcher, Claire M.; Yearsley, Jonathan M.

2014-01-01

Peatlands represent a globally important carbon store; however, the human exploitation of this ecosystem is increasing both the frequency and severity of fires on drained peatlands. Yet, the interactions between the hydrological conditions (ecotopes), the fuel types being burned, the burn severity, and the charring temperatures (pyrolysis intensity) remain poorly understood. Here we present a post-burn assessment of a fire on a lowland raised bog in Co. Offaly, Ireland (All Saints Bog). Three burn severities were identified in the field (light, moderate, and deeply burned), and surface charcoals were taken from 17 sites across all burn severities. Charcoals were classified into two fuel type categories (either ground or aboveground fuel) and the reflectance of each charcoal particle was measured under oil using reflectance microscopy. Charcoal reflectance shows a positive relationship with charring temperature and as such can be used as a temperature proxy to reconstruct minimum charring temperatures after a fire event. Resulting median reflectance values for ground fuels are 1.09 ± 0.32%Romedian, corresponding to estimated minimum charring temperatures of 447°C ± 49°C. In contrast, the median charring temperatures of aboveground fuels were found to be considerably higher, 646°C ± 73°C (3.58 ± 0.77%Romedian). A mixed-effects modeling approach was used to demonstrate that the interaction effects of burn severity, as well as ecotope classes, on the charcoal reflectance is small compared to the main effect of fuel type. Our findings reveal that the different fuel types on raised bogs are capable of charring at different temperatures within the same fire, and that the pyrolysis intensity of the fire on All Saints Bog was primarily driven by the fuel types burning, with only a weak association to the burn severity or ecotope classes. PMID:25566288

Vertical Stratification of Peat Pore Water Dissolved Organic Matter Composition in a Peat Bog in Northern Minnesota: Pore Water DOM composition in a peat bog

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

Tfaily, Malak M.; Wilson, Rachel M.; Cooper, William T.

We characterized dissolved organic matter (DOM) composition throughout the peat column at the Marcell S1 forested bog in northern Minnesota and tested the hypothesis that redox oscillations associated with cycles of wetting and drying at the surface of the fluctuating water table correlate with increased carbon, sulfur and nitrogen turn over. We found significant vertical stratification of DOM molecular composition and EEM-PARAFAC components within the peat column. In particular the intermediate depth zone (~ 50 cm) was identified as a zone where maximum decomposition and turnover is taking place. Surface DOM was dominated by inputs from surface vegetation. The intermediate-depthmore » zone was an area of high organic matter reactivity and increased microbial activity with diagenetic formation of many unique compounds, among them polycyclic aromatic compounds (PAC) that contain both nitrogen and sulfur heteroatoms. These compounds have been previously observed in coal-derived compounds and were assumed to be responsible for coal's biological activity. Biological processes triggered by redox oscillations taking place at the intermediate depth zone of the peat profile at the S1 bog are assumed to be responsible for the formation of these heteroatomic PACs in this system. Alternatively these compounds could stem from black carbon and nitrogen derived from fires that have occurred at the site in the past. Surface and deep DOM exhibited more similar characteristics, compared to the intermediate-depth zone, with the deep layer exhibiting greater input of microbially degraded organic matter than the surface suggesting that the entire peat profile consists of similar parent material at different degrees of decomposition and that lateral and vertical advection of pore water from the surface to the deeper horizons is responsible for such similarities. Our findings suggest that molecular composition of DOM in peatland pore water is dynamic and is a function of ecosystem activity, water table and redox oscillation and porewater advection.« less

Peatland Microbial Communities and Decomposition Processes in the James Bay Lowlands, Canada

PubMed Central

Preston, Michael D.; Smemo, Kurt A.; McLaughlin, James W.; Basiliko, Nathan

2012-01-01

Northern peatlands are a large repository of atmospheric carbon due to an imbalance between primary production by plants and microbial decomposition. The James Bay Lowlands (JBL) of northern Ontario are a large peatland-complex but remain relatively unstudied. Climate change models predict the region will experience warmer and drier conditions, potentially altering plant community composition, and shifting the region from a long-term carbon sink to a source. We collected a peat core from two geographically separated (ca. 200 km) ombrotrophic peatlands (Victor and Kinoje Bogs) and one minerotrophic peatland (Victor Fen) located near Victor Bog within the JBL. We characterized (i) archaeal, bacterial, and fungal community structure with terminal restriction fragment length polymorphism of ribosomal DNA, (ii) estimated microbial activity using community level physiological profiling and extracellular enzymes activities, and (iii) the aeration and temperature dependence of carbon mineralization at three depths (0–10, 50–60, and 100–110 cm) from each site. Similar dominant microbial taxa were observed at all three peatlands despite differences in nutrient content and substrate quality. In contrast, we observed differences in basal respiration, enzyme activity, and the magnitude of substrate utilization, which were all generally higher at Victor Fen and similar between the two bogs. However, there was no preferential mineralization of carbon substrates between the bogs and fens. Microbial community composition did not correlate with measures of microbial activity but pH was a strong predictor of activity across all sites and depths. Increased peat temperature and aeration stimulated CO2 production but this did not correlate with a change in enzyme activities. Potential microbial activity in the JBL appears to be influenced by the quality of the peat substrate and the presence of microbial inhibitors, which suggests the existing peat substrate will have a large influence on future JBL carbon dynamics. PMID:22393328

Small-scale variability in peatland pore-water biogeochemistry, Hudson Bay Lowland, Canada.

PubMed

Ulanowski, T A; Branfireun, B A

2013-06-01

The Hudson Bay Lowland (HBL) of northern Ontario, Manitoba and Quebec, Canada is the second largest contiguous peatland complex in the world, currently containing more than half of Canada's soil carbon. Recent concerns about the ecohydrological impacts to these large northern peatlands resulting from climate change and resource extraction have catalyzed a resurgence in scientific research into this ecologically important region. However, the sheer size, heterogeneity and elaborate landscape arrangements of this ecosystem raise important questions concerning representative sampling of environmental media for chemical or physical characterization. To begin to quantify such variability, this study assessed the small-scale spatial (1m) and short temporal (21 day) variability of surface pore-water biogeochemistry (pH, dissolved organic carbon, and major ions) in a Sphagnum spp.-dominated, ombrotrophic raised bog, and a Carex spp.-dominated intermediate fen in the HBL. In general, pore-water pH and concentrations of dissolved solutes were similar to previously reported literature values from this region. However, systematic sampling revealed consistent statistically significant differences in pore-water chemistries between the bog and fen peatland types, and large within-site spatiotemporal variability. We found that microtopography in the bog was associated with consistent differences in most biogeochemical variables. Temporal changes in dissolved solute chemistry, particularly base cations (Na(+), Ca(2+) and Mg(2+)), were statistically significant in the intermediate fen, likely a result of a dynamic connection between surficial waters and mineral-rich deep groundwater. In both the bog and fen, concentrations of SO4(2-) showed considerable spatial variability, and a significant decrease in concentrations over the study period. The observed variability in peatland pore-water biogeochemistry over such small spatial and temporal scales suggests that under-sampling in northern peatland environments could lead to erroneous conclusions concerning the abundance and distribution of natural elements and pollutants alike. Copyright © 2013 Elsevier B.V. All rights reserved.

Fire severity is more sensitive to low fuel moisture content on Calluna heathlands than on peat bogs.

PubMed

Grau-Andrés, Roger; Davies, G Matt; Gray, Alan; Scott, E Marian; Waldron, Susan

2018-03-01

Moorland habitats dominated by the dwarf shrub Calluna vulgaris provide important ecosystem services. Drought is projected to intensify throughout their range, potentially leading to increased fire severity as moisture is a key control on severity. We studied the effect of low fuel moisture content (FMC) on fire severity by using 2×2m rain-out shelters prior to completing 19 experimental fires in two sites in Scotland (UK): a dry heath with thin organic soils and a raised bog with deep, saturated peat, both dominated by Calluna vulgaris. Reduced FMC of the moss and litter (M/L) layer at both sites, and the soil moisture of the dry heath, increased fire-induced consumption of the M/L layer and soil heating at both sites. Increase in fire severity was greater at the dry heath than at the raised bog, e.g. average maximum temperatures at the soil surface increased from 31°C to 189°C at the dry heath, but only from 10°C to 15°C at the raised bog. Substantial M/L layer consumption was observed when its FMC was below 150%. This led to larger seasonal and daily soil temperature fluctuation, particularly at the dry heath during warm months. The results suggest that low FMC following predicted changes in climate are likely to increase wildfire severity and that the impact on vegetation composition and carbon stores may be greater at heathlands than at peatlands. Managed burning aiming to minimise fire severity (e.g. ignition of the M/L layer and exposure to lethal temperatures of ericoid seeds) should be carried out when the FMC of the M/L layer is above 150% and the FMC of the soil is above 200-300%. Copyright © 2017 Elsevier B.V. All rights reserved.

Reduction of atmospheric polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) during the 2008 Beijing Olympic games.

PubMed

Li, Yingming; Wang, Thanh; Wang, Pu; Ding, Lei; Li, Xiaomin; Wang, Yawei; Zhang, Qinghua; Li, An; Jiang, Guibin

2011-04-15

A total of 120 air samples were collected at three urban and one rural location in Beijing, China in the summers of 2007-2010, and before, during, and after the Beijing 2008 Olympic Games (BOG), in order to assess the effectiveness of long-term and short-term emission-control measures in reducing polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in the atmosphere. During the BOG (August, 2008), the PCDD/Fs concentrations decreased to an average value of 1150 fg m(-3) (63 fg I-TEQ m(-3)), which was reduced by approximately 70% from the average in 2007 and by 29% from that in July 2008, before the Olympic event began. Although 2009-2010 levels of PCDD/Fs were significantly higher than 2008, the overall temporal trend was decreasing for summer months during the sampling campaign period. The apparent half-lives of atmospheric PCDD/Fs were estimated to be 3.2-5.8 years by statistically regressing the logarithm PCDD/Fs concentrations versus the number of years passed since 2006. The air concentrations of total suspended particulates (TSP) during the BOG ranged between 135 and 183 μg m(-3), showing a 52% reduction from 2007 and 26% decrease from those prior to the Olympic event. No significant relationships were found between meteorological parameters (temperature, humidity, and wind speed) and PCDD/Fs or TSP during the BOG, whereas the PCDD/Fs concentrations were significantly dependent on the air quality (p < 0.05, positive against TSP and negative against visibility). This work is one of few temporal trend studies of atmospheric PCDD/Fs in mainland China, and provides unique insight into the effects of large-scale control measures in improving air quality and reducing one of the most ubiquitous and toxic organic pollutants in the environment.

Holocene coseismic and aseismic uplift of Isla Mocha, south-central Chile

USGS Publications Warehouse

Nelson, A.R.; Manley, W.F.

1992-01-01

During the past 6000 years Isla Mocha, a 12 km-long island 30 km off the coast of south-central Chile, experienced a 38 m fall of relative sea level caused primarily by rapid tectonic uplift of the island. As many as 18 raised shorelines (strandlines) record this uplift. Historic accounts of uplift during the great earthquakes (M > 8) of 1835 and 1960 suggest some of the more prominent prehistoric strandlines also emerged during great earthquakes on the interface between the Nazca and South America plates. But the close elevational spacing of strandlines, subdued morphology of strandline beaches, scarcity of exposed bedrock wave-cut platforms, and the extremely high rates of aseismic uplift (ca. 70 mm/yr) of the island since the last great earthquake suggest that many strandlines were raised by aseismic rather than coseismic uplift. Strandline heights and 14 new radiocarbon ages on marine shells show that the present-day uplift rate is more than three times the net rate (ca. 20 mm/yr) of the past 1000 years. The recent high rate probably reflects increased aseismic slip on an inferred thrust fault in the overriding South America plate. Isla Mocha overlies an area of high stress concentration between two major segments of the Chilean subduction zone. The inferred high rate of slip on the thrust fault may be a response to stress changes on the plate interface near the boundary between the segments. ?? 1992.

Geomorphic Response to Spatial and Temporal Tectonic uplift on the Kenya Rift of East African Rift System

NASA Astrophysics Data System (ADS)

Xue, L.; Abdelsalam, M. G.

2017-12-01

Tectonic uplifts of the shoulders of the East Africa Rift System (EARS) have significant impact on the geological record by reorganizing drainage systems, increasing sediment supply, and changing climate and biogeography. Recent studies in geochronology, geomorphology and geophysics have provided some understanding of the timing of tectonic uplift and its distribution pattern of the (EARS). We do not know how the vertical motion is localized along the rift axis and the relative roles of upwelling of magma and rift extensional processes play in tectonic uplift history. This work presents detailed morphometric study of the fluvial landscape response to the tectonic uplift and climate shifting of the Kenya Rift shoulders in order to reconstruct their incision history, with special attention to timing, location, and intensity of uplift episodes. This work compiles the Shuttle Radar Topography Mission (SRTM) Digital Elevation Model (DEM) and Sentinel-2A data, summarized previous 39Ar-40Ar and thermochronology data, and calculates long-term incision rate and geomorphic proxies (normalized steepness and chi-integral) along the Kenya Rift. It also models the age of tectonic/climatic events by using knickpoint celerity model and R/SR integrative approach. It found that the maximum long-term incision rates of 300 mm/kyr to be at the central Kenya Rift, possibly related to the mantle-driven process and rapid tectonic uplift. The geomorphic proxies indicate southward decreasing pattern of the short-term incision rate, possibly related to the migration of the mantle plume.

Geologic history of the Colorado River: Chapter C in The Colorado River region and John Wesley Powell (Professional Paper 669)

USGS Publications Warehouse

Hunt, Charles B.

1969-01-01

John Wesley Powell clearly recognized that the spectacular features of the Colorado River - its many grand canyons - were dependent upon the structural history of the mountainous barriers crossed by the river. He conceived of three different historical relationships between rivers and structural features: (1) Newly uplifted land surfaces have rivers that flow down the initial slope of the uplift; these relationships he termed consequent. (2) A river may be older than an uplift that it crosses because it has been able to maintain its course by eroding downward as the uplift progresses; this relationship he named antecedent. (3) An uplifted block may have been buried by younger deposits upon which a river becomes established. The river, in cutting downward, uncovers the uplifted block and becomes incised into it; this relationship he called superimposed.The geologic history of the Colorado River involves all three relationships. In addition, although the position of the river course through a particular structural barrier may have been the result of superposition, the depth of the canyon at that point may be largely due to renewed uplift of the barrier; such deepening of the canyon, therefore, is due to antecedence. The problem of the Colorado River remains today very much as G. K. Gilbert stated it nearly 100 years ago: "How much is antecedent and how much is superimposed?" The question must be asked separately for each stretch of the river.

Differential Effects of High Atmospheric N and S Deposition on Bog Plant/Lichen Tissue and Porewater Chemistry across the Athabasca Oil Sands Region.

PubMed

Wieder, R Kelman; Vile, Melanie A; Scott, Kimberli D; Albright, Cara M; McMillen, Kelly J; Vitt, Dale H; Fenn, Mark E

2016-12-06

Oil extraction and development activities in the Athabasca Oil Sands Region of northern Alberta, Canada, release NO x , SO x , and NH y to the atmosphere, ultimately resulting in increasing N and S inputs to surrounding ecosystems through atmospheric deposition. Peatlands are a major feature of the northern Alberta landscape, with bogs covering 6-10% of the land area, and fens covering 21-53%. Bulk deposition of NH 4 + -N, NO 3 - -N, dissolved inorganic N (DIN), and SO 4 2- -S, was quantified using ion-exchange resin collectors deployed at 23 locations, over 1-6 years. The results reveal maximum N and S deposition of 9.3 and 12.0 kg ha -1 yr -1 , respectively, near the oil sands industrial center (the midpoint between the Syncrude and Suncor upgrader stacks), decreasing with distance to a background deposition of 0.9 and 1.1 kg ha -1 yr -1 , respectively. To assess potential influences of high N and S deposition on bogs, we quantified N and S concentrations in tissues of two Sphagnum species, two lichen species, and four vascular plant species, as well as surface porewater concentrations of H + , NH 4 + -N, NO 3 - -N, SO 4 2- -S and dissolved organic N in 19 ombrotrophic bogs, distributed across a 3255 km 2 sampling area surrounding the oil sands industrial center. The two lichen species (Evernia mesomorpha and Cladonia mitis), two vascular plant species (Rhododendron groenlandicum and Picea mariana), and to a lesser extent one moss (Sphagnum fuscum), showed patterns of tissue N and S concentrations that were (1) highest near the oil sands industrial center and (2) positively correlated with bulk deposition of N or S. Concentrations of porewater H + and SO 4 2- -S, but not of NH 4 + -N, NO 3 - -N, DIN, or dissolved inorganic N, also were higher near the oil sands industrial center than at more distant locations. The oil sands region of northern Alberta is remote, with few roads, posing challenges to the monitoring of oil sands-related N and S deposition. Quantification of N and S concentrations in bog plant/lichen tissues and porewaters may serve as a monitoring tool to assess both the local intensity and the spatial extent of bulk N and S deposition, and as harbingers of potential shifts in ecosystem structure and function.

Multiproxy records of Holocene climate and glacier variability from sediment cores in the Cordillera Vilcabamba of southern Peru

NASA Astrophysics Data System (ADS)

Schweinsberg, A. D.; Licciardi, J. M.; Rodbell, D. T.; Stansell, N.; Tapia, P. M.

2012-12-01

Sediments contained in glacier-fed lakes and bogs provide continuous high-resolution records of glacial activity, and preserve multiproxy evidence of Holocene climate change. Tropical glacier fluctuations offer critical insight on regional paleoclimatic trends and controls, however, continuous sediment records of past tropical climates are limited. Recent cosmogenic 10Be surface exposure ages of moraine sequences in the Cordillera Vilcabamba of southern Peru (13°20'S latitude) reveal a glacial culmination during the early Holocene and a less extensive glaciation coincident with the Little Ice Age of the Northern Hemisphere. Here we supplement the existing 10Be moraine chronology with the first continuous records of multiproxy climate data in this mountain range from sediment cores recovered from bogs in direct stratigraphic contact with 10Be-dated moraines. Radiocarbon-dated sedimentological changes in a 2-meter long bog core reveal that the Holocene is characterized by alternating inorganic and organic-rich laminae, suggesting high-frequency climatic variability. Carbon measurements, bulk density, and bulk sedimentation rates are used to derive a record of clastic sediment flux that serves as a proxy indicator of former glacier activity. Preliminary analyses of the bog core reveal approximately 70 diatom taxa that indicate both rheophilic and lentic environments. Initial results show a general decrease in magnetic susceptibility and clastic flux throughout the early to mid-Holocene, which suggests an interval of deglaciation. An episode of high clastic flux from 3.8 to 2.0 ka may reflect a late Holocene glacial readvance. Volcanic glass fragments and an anomalous peak in magnetic susceptibility may correspond to the historical 1600 AD eruption of Huaynaputina. Ten new bog and lake sediment cores were collected during the 2012 field expedition and analytical measurements are underway. Ongoing efforts are focused on analyzing diatom assemblage data, developing detailed records of biogenic silica, clastic sediment flux, and magnetic susceptibility, and augmenting the 10Be moraine chronology with precise limiting radiocarbon ages to provide a more comprehensive assessment of regional climate and environmental indicators. These new paleoclimatic records will fill a large geographic gap in available proxy data and contribute toward a more complete understanding of Holocene climate variability in southern Peru. In addition, the basal radiocarbon ages being developed from sediments in contact with 10Be-dated moraines will place limits on the cosmogenic 10Be production rate in the high Andes.

Eddy covariance measurements of greenhouse gases from a restored and rewetted raised bog ecosystem.

NASA Astrophysics Data System (ADS)

Lee, S. C.; Christen, A.; Black, T. A.; Johnson, M. S.; Ketler, R.; Nesic, Z.; Merkens, M.

2015-12-01

Wetland ecosystems play a significant role in the global carbon (C) cycle. Wetlands act as a major long-term storage of carbon by sequestrating carbon-dioxide (CO2) from the atmosphere. Meanwhile, they can emit significant amounts of methane (CH4) due to anaerobic microbial decomposition. The Burns Bog Ecological Conservancy Area (BBECA) is recognized as one of Canada's largest undeveloped natural areas retained within an urban area. Historically, it has been substantially reduced in size and degraded by peat mining and agriculture. Since 2005, the bog has been declared a conservancy area, and the restoration efforts in BBECA focus on rewetting the disturbed ecosystems to promote a transition back to a raised bog. A pilot study measured CH4, CO2 and N2O exchanges in 2014 and concluded to monitor CO2, CH4 fluxes continuously. From the perspective of greenhouse gas (GHG) emissions, CO2 sequestered in bog needs to be protected and additional CO2 and CH4 emissions due to land-cover change need to be reduced by wise management. In this study, we measured the growing-season (June-September) fluxes of CO2 and CH4 exchange using eddy covariance (EC). A floating platform with an EC system for both CO2 (closed-path) and CH4 (open-path) began operation in June 2015. During the growing-season, gross ecosystem photosynthesis (GEP) and ecosystem respiration (Re) averaged 5.87 g C m-2 day-1 and 2.02 g C m-2 day-1, respectively. The magnitude of GEP and Re were lower than in previous studies of pristine northern peatlands. The daily average CH4 emission was 0.99 (±1.14) g C m-2 day-1 and it was higher than in most previous studies. We also characterized how environmental factors affected the seasonal dynamics of these exchanges in this disturbed peatland. Our measurements showed that soil temperature and soil water content were major drivers of seasonal changes of GHG fluxes. The daily average GHG warming potential (GWP) of the emissions in the growing seasons (from CO2 and CH4) totals to 37.09 g CO2e m-2 day-1. CH4 was the significant constributor (99 % of GHG emissions) indicating that GHG exchange due to photosynthesis and respiration was of secondary order. Although oxygen limitation due to the high water table caused by the restoration strategy suppressed the Re it also promoted substantial CH4 formation under anoxic conditions.

Microbial communities of the deep unfrozen: Do microbes in taliks increase permafrost carbon vulnerability? (Invited)

NASA Astrophysics Data System (ADS)

Waldrop, M. P.; Blazewicz, S.; Jones, M.; Mcfarland, J. W.; Harden, J. W.; Euskirchen, E. S.; Turetsky, M.; Hultman, J.; Jansson, J.

2013-12-01

The vast frozen terrain of northern latitude ecosystems is typically thought of as being nearly biologically inert for the winter period. Yet deep within the frozen ground of northern latitude soils reside microbial communities that can remain active during the winter months. As we have shown previously, microbial communities may remain active in permafrost soils just below the freezing point of water. Though perhaps more importantly, microbial communities persist in unfrozen areas of water, soil, and sediment beneath water bodies the entire year. Microbial activity in taliks may have significant impacts on biogeochemical cycling in northern latitude ecosystems because their activity is not limited by the winter months. Here we present compositional and functional data, including long term incubation data, for microbial communities within permafrost landscapes, in permafrost and taliks, and the implications of these activities on permafrost carbon decomposition and the flux of CO2 and CH4. Our experiment was conducted at the Alaska Peatland Experiment (APEX) within the Bonanza Creek LTER in interior Alaska. Our site consists of a black spruce forest on permafrost that has degraded into thermokarst bogs at various times over the last five hundred years. We assume the parent substrate of the deep (1-1.5m) thermokarst peat was similar to the nearby forest soil and permafrost C before thaw. At this site, flux tower and autochamber data show that the thermokarst bog is a sink of CO2 , but a significant source of CH4. Yet this does not tell the whole story as these data do not fully capture microbial activity within the deep unfrozen talik layer. There is published evidence that within thermokarst bogs, relatively rapid decomposition of old forest floor material may be occurring. There are several possible mechanisms for this pattern; one possible mechanism for accelerated decomposition is the overwintering activities of microbial communities in taliks of thermokarst soils. To test this idea, we conducted anaerobic incubations of deep (1m) bog soils at two different temperatures to determine microbial temperature response functions. We also measured soil profile CO2 and CH4 concentrations and functional gene assays of the deep bog microbial community. Incubation data in combination with overwinter temperature profiles show that the talik has high potential rates of CO2 and CH4 production compared to the mass of C from forest floor and permafrost C to 1m depth. Results highlight the potential importance of taliks affecting the vulnerability of permafrost carbon to decomposition and reduction to methane.

Atmospheric trace metal inputs in the Misten bog (East Belgium): Special attention to sampling techniques and site-spatial variability.

NASA Astrophysics Data System (ADS)

Allan, Mohammed; Fagel, Nathalie; de Vleeschouwer, François; Mattielli, Nadine; Piotrowska, Natalia; Sikorski, Jarek; Sonke, Jeroen E.; Le Roux, Gaël.

2010-05-01

Peat bogs have a great potential to record anthropogenic inputs via their constituting mosses, because they draw their nutrients only from the atmosphere. These atmospheric inputs can be studied thanks to geochemical characteristics such as trace metal concentrations. Coupling lead isotopes to elemental geochemistry allows one to decipher between natural (erosion of rocks) and anthropogenic (pollution due to industrial development, vehicles...) inputs. The purpose of our work was to study the pollution history of trace metals in the region of Misten (Belgium) at a local and a regional level, and to place modern industrial pollution in this region in a wider historical perspective. Four peat cores (01W, 04W, 05W and 06W) were collected in 2008 in the Misten bog (Hautes-Fagnes plateau, E-Belgium) and studied for their trace metal and lead isotopic signatures. Analyses were accompanied by coupled 210Pb-14C age models in order to estimate the mercury and lead accumulation rates in each core and compare them to other European records. The Hg record was compared to the various anthropogenic sources as determined by Pb isotopes. The Hg concentration profiles resemble those of Pb, an element known to be immobile in peatlands. The correlation between these two metals suggests a predominant anthropogenic source of Hg (and Pb). In the W06 core, low and stable Hg accumulation rates (0.9-3.1 μg m-2 yr-1) are found in the lower layers (503-1823AD). High Hg accumulation rates are found in the surface and sub-surface layers (post-1823AD) and peak at 123.3 μg m-2 yr-1 (1969AD). In 01W, the lead enrichment factor (Pb E.F.) coupled with the continuous drop in 206Pb/204Pb, 207Pb/204Pb, 208Pb/204Pb isotopic ratios since 539 AD until 1973AD indicates the growing importance of the non-radiogenic Pb released from anthropogenic activities. The highest concentrations of Pb (613-662 µg g-1) have been found near the surface of the bog dated between 1902 and 1954AD. The Pb E.F. also significantly increased during the Industrial Revolution, and subsequently decreased due to the phasing out of leaded gasoline. Main results for Pb in 01W and Hg in 06W will be compared with the 2 other cores and previously published results collected in 2007 at another location in the same peatland. Differences in concentrations and chronology will be discussed in terms of (1) differences in the topography of the bog, (2) differences in the surface vegetation of the bog, which could have led to differential trapping and retention of lead, for example, and different retention of vegetation during sampling at the sites where the corers were inserted, (3) different effects induced by the operating mechanism of the corers, (4) operator-induced effects, e.g. leading to loss of surface material before or during coring.

Annual greenhouse gas budget for a bog ecosystem undergoing restoration by rewetting

NASA Astrophysics Data System (ADS)

Lee, Sung-Ching; Christen, Andreas; Black, Andrew T.; Johnson, Mark S.; Jassal, Rachhpal S.; Ketler, Rick; Nesic, Zoran; Merkens, Markus

2017-06-01

Many peatlands have been drained and harvested for peat mining, agriculture, and other purposes, which has turned them from carbon (C) sinks into C emitters. Rewetting of disturbed peatlands facilitates their ecological recovery and may help them revert to carbon dioxide (CO2) sinks. However, rewetting may also cause substantial emissions of the more potent greenhouse gas (GHG) methane (CH4). Our knowledge of the exchange of CO2 and CH4 following rewetting during restoration of disturbed peatlands is currently limited. This study quantifies annual fluxes of CO2 and CH4 in a disturbed and rewetted area located in the Burns Bog Ecological Conservancy Area in Delta, BC, Canada. Burns Bog is recognized as the largest raised bog ecosystem on North America's west coast. Burns Bog was substantially reduced in size and degraded by peat mining and agriculture. Since 2005, the bog has been declared a conservancy area, with restoration efforts focusing on rewetting disturbed ecosystems to recover Sphagnum and suppress fires. Using the eddy covariance (EC) technique, we measured year-round (16 June 2015 to 15 June 2016) turbulent fluxes of CO2 and CH4 from a tower platform in an area rewetted for the last 8 years. The study area, dominated by sedges and Sphagnum, experienced a varying water table position that ranged between 7.7 (inundation) and -26.5 cm from the surface during the study year. The annual CO2 budget of the rewetted area was -179 ± 26.2 g CO2-C m-2 yr-1 (CO2 sink) and the annual CH4 budget was 17 ± 1.0 g CH4-C m-2 yr-1 (CH4 source). Gross ecosystem productivity (GEP) exceeded ecosystem respiration (Re) during summer months (June-August), causing a net CO2 uptake. In summer, high CH4 emissions (121 mg CH4-C m-2 day-1) were measured. In winter (December-February), while roughly equal magnitudes of GEP and Re made the study area CO2 neutral, very low CH4 emissions (9 mg CH4-C m-2 day-1) were observed. The key environmental factors controlling the seasonality of these exchanges were downwelling photosynthetically active radiation and 5 cm soil temperature. It appears that the high water table caused by ditch blocking suppressed Re. With low temperatures in winter, CH4 emissions were more suppressed than Re. Annual net GHG flux from CO2 and CH4 expressed in terms of CO2 equivalents (CO2 eq.) during the study period totalled -22 ± 103.1 g CO2 eq. m-2 yr-1 (net CO2 eq. sink) and 1248 ± 147.6 g CO2 eq. m-2 yr-1 (net CO2 eq. source) by using 100- and 20-year global warming potential values, respectively. Consequently, the ecosystem was almost CO2 eq. neutral during the study period expressed on a 100-year time horizon but was a significant CO2 eq. source on a 20-year time horizon.

Linking major and trace element headwater stream concentrations to DOC release and hydrologic conditions in a bog and peaty riparian zone

NASA Astrophysics Data System (ADS)

Broder, Tanja; Biester, Harald

2017-04-01

Peatlands and organic-rich riparian zones are known to export large amounts of dissolved organic carbon (DOC) to surface water. In organic-rich, acidic headwater streams main carriers for element export are dissolved organic matter (DOM) and organic-iron complexes. In this environment DOM might also act as major carrier for metals, which otherwise may have a low solubility. This study examines annual and short term event-based variations of major and trace elements in a headwater catchment. Patterns are used to trace hydrological pathways and element sources under different hydrologic preconditions. Furthermore, it elucidates the importance of DOC as carrier of different elements in a bog and a peaty riparian catchment. The study was conducted in a small headwater stream draining an ombrotrophic peatland with an adjacent forested area with peaty riparian soils in the Harz Mountains (Germany). Discharge sampling was conducted weekly at two sites from snowmelt to begin of snowfall and in high resolution during selected discharge events in 2013 and 2014. Element concentrations were measured by means of ICP-MS and ICP-OES. A PCA was performed for each site and for annual and event datasets. Results show that a large number of element concentrations strongly correlate with DOC concentrations at the bog site. Even elements like Ca and Mg, which are known to have a low affinity to DOC. Congruently, the first principal component integrates the DOC pattern (element loadings > 0.8: Ca, Fe, Mg, Mn, Zn, As, Sr, Cd, DOC) and explained about 35 % of total variance and even 50 % during rain events (loadings > 0.8: Al, Ca, Fe, Mg, Mn, Zn, Li, Co, As, Sr, Cd, Pb, DOC). The study cannot verify that all correlating elements bind to DOC. It is likely that also a common mobilization pattern in the upper peat layer by plant decomposition causes the same response to changes in hydrologic pathways. Additionally, a low mineral content and an enrichment of elements like Fe and Mn in the upper peat layers due to prevailing redox conditions might play a major role in a bog environment. At the peaty riparian zone only Ca, Fe, and Sr strongly correlated with DOC over the annual record. The PCA of the annual record display no clear DOC component here, but indicates that DOC is influenced by Component one (element loadings > 0.8: Ca, Mg, Zn, Co, Sr) and two (Al, V, La, Pb, U) suggesting different DOC sources in the peaty riparian zone. A large number of elements correlate with DOC during rain event sampling at the riparian zone. In contrast to the bog site the event-based riparian zone PCA distinguished a clear discharge related component with mineral, groundwater related elements (K, Rb, In, Cs, NO3- and SO42-). Pattern of the mineral and DOC components prove that during base flow discharge is generated in a shallow groundwater layer and successively increases upward to the organic-rich upper soil layer with increasing discharge. Contrarily, bog element pattern confirm a dominating surface-near discharge, due to high hydraulic conductivities.

Modeling the Climatic Effect of Convergent Tectonics During the Middle to Late Miocene: Effective Closure of the Indonesian Seaway, Himalayan Uplift and the East Asian Monsoon

NASA Astrophysics Data System (ADS)

DeConto, R. M.; MacConnell, A.; Leckie, R.

2001-05-01

During the middle to late Miocene, the northward drift of Australia and New Guinea progressively restricted Indonesian throughflow (ITF). Today, ITF plays an important role in modulating inter-basin fresh water flux, heat transport, and the volume of the Western Pacific Warm Pool (WPWP). Today's WPWP is a center for deep convection that contributes considerable diabatic heating to the tropical atmosphere, affecting both the Walker and Hadley circulation. The WPWP fuels the East Asian Monsoon with moisture and latent heat and is an important component of ENSO. As the Indonesian Seaway became restricted, India was impinging on Asia. Asian continentality was increased and Himalayan/Tibetan uplift begun affecting zonal atmospheric flow and land-surface albedo. In order to better understand the climate system's response to changing Miocene paleogeography (horizontal and vertical tectonics), we have begun a series of climate model experiments using atmosphere, ocean, and coupled atmosphere-ocean general circulation models (GCMs). The GCM experiments are designed to isolate the possible response to effective Indonesian gateway closure within the framework of evolving Miocene Paleogeography between 11 and 7 Ma. In the first phase of our modeling study, an AGCM was used to test the sensitivity of tropical Indo-Pacific and Asian climate (including monsoonal intensity) to the presence of a WPWP in a pre and post Himalayan/Tibetan Plateau world. The results of the GCM simulations will be discussed in the context of the hypotheses that 1) a proto-WPWP became established as the Indonesian Seaway became increasingly restricted during the late middle to late Miocene; and 2) the growth of the WPWP had a first order affect on tropical Pacific climate and the East Asian monsoon.

LiDAR Mapping of Earthquake Uplifted Paleo-shorelines, Southern Wairarapa Coast, North Island, New Zealand

NASA Astrophysics Data System (ADS)

Valenciano, J.; Angenent, J.; Marshall, J. S.; Clark, K.; Litchfield, N. J.

2017-12-01

The Hikurangi subduction margin along the east coast of the North Island, New Zealand accommodates oblique convergence of the Pacific Plate westward beneath the Australian plate at 45 mm/yr. Pronounced forearc uplift occurs at the southern end of the margin along the Wairarapa coast, onshore of the subducting Hikurangi plateau. Along a narrow coastal lowland, a series of uplifted Holocene marine terraces and beach ridges preserve a geologic record of prehistoric coseismic uplift events. In January 2017, we participated in the Research Experience for Undergraduates (REU) program of the NSF SHIRE Project (Subduction at Hikurangi Integrated Research Experiment). We visited multiple coastal sites for reconnaissance fieldwork to select locations for future in-depth study. For the coastline between Flat Point and Te Kaukau Point, we used airborne LiDAR data provided by Land Information New Zealand (LINZ) to create ArcGIS digital terrain models for mapping and correlating uplifted paleo-shorelines. Terrace elevations derived from the LiDAR data were calibrated through the use of Real Time Kinematic (RTK) GPS surveying at one field site (Glenburn Station). Prior field mapping and radiocarbon dating results (Berryman et al., 2001; Litchfield and Clark, 2015) were used to guide our LiDAR mapping efforts. The resultant maps show between four and seven uplifted terraces and associated beach ridges along this coastal segment. At some sites, terrace mapping and lateral correlation are impeded by discontinuous exposures and the presence of landslide debris, alluvial fan deposits, and sand dunes. Tectonic uplift along the southern Hikurangi margin is generated by a complex interaction between deep megathrust slip and shallow upper-plate faulting. Each uplifted Holocene paleo-shoreline is interpreted to represent a single coseismic uplift event. Continued mapping, surveying, and age dating may help differentiate between very large margin-wide megathrust earthquakes (M8.0-9.0+) and smaller, more localized upper-plate thrust events (M7.0-8.0). Both of these earthquake types pose a significant seismic and tsunami hazard for New Zealand residents.

Neogene Uplift and Magmatism of Anatolia: New Insights from Drainage Analysis and Basalt Geochemistry

NASA Astrophysics Data System (ADS)

McNab, F.; Ball, P.; Hoggard, M.; White, N.

2017-12-01

The origin of Anatolia's high elevation and low relief plateaux has been the subject of much recent debate. Marine sedimentary rocks distributed across Central and Eastern Anatolia require significant regional uplift in Neogene times. This uplift cannot be explained by the present-day pattern of crustal deformation which, particularly across Central and Western Anatolia, is dominanted by strike-slip and extensional faulting. Positive long wavelength free-air gravity anomalies combined with slow upper mantle seismic wave speeds suggest that the sub-lithospheric mantle provides substantial topographic support. A range of geodynamic processes have been invoked, including complex slab fragmentation and lithospheric delamination. The temporal and spatial evolution of the Anatolian landscape should be recorded by drainage networks. Indeed, major catchments contain prominent knickzones with heights of hundreds of meters and length scales of several hundred kilometers. The stream power formulation for fluvial erosion permits these knickzones to be interpreted in terms of uplift history along a river's length. Here, we jointly invert an inventory of 1,844 river profiles to determine a spatial and temporal uplift rate history. When calibrated against independent observations of uplift rate, the resultant history provides significant new constraints for the evolution of Anatolian topography. In our model, the bulk of this topography appears to grow in Neogene times. Uplift initiates in Eastern Anatolia and propagates westward at uplift rates of up to 0.5 mm/yr. Coeval with this phase of uplift, abundant basaltic magmatism has occurred throughout Anatolia. We have compiled an extensive database of published geochemical analyses. Using this database, we analyse spatial and temporal patterns of basaltic compositions to discriminate between different modes of melt generation. Two independent techniques for estimating asthenospheric potential temperatures from the compositions of high-Mg basalts have been used. Elevated temperatures of c. 1380 ºC occur beneath Eastern Anatolia with a notable decrease towards the west. Overall, our results imply that the spatial and temporal evolution Anatolian topography is controlled by temperature variations within the asthenospheric mantle.

GPS Imaging suggests links between climate, magmatism, seismicity, and tectonics in the Sierra Nevada-Long Valley Caldera-Walker Lane system, western United States

NASA Astrophysics Data System (ADS)

Hammond, W. C.; Blewitt, G.; Kreemer, C.; Smith, K.

2017-12-01

The Walker Lane is a region of complex active crustal transtension in the western Great Basin of the western United States, accommodating about 20% of the 50 mm/yr relative motion between the Pacific and North American plates. The Long Valley caldera lies in the central Walker Lane in eastern California, adjacent to the eastern boundary of the Sierra Nevada/Great Valley microplate, and experiences intermittent inflation, uplift, and volcanic unrest from the magma chamber that resides at middle crustal depths. Normal and transform faults accommodating regional tectonic transtension pass by and through the caldera, complicating the interpretation of the GPS-measured strain rate field, estimates of fault slip rates, and seismic hazard. Several dozen continuously recording GPS stations measure strain and uplift in the area with mm precision. They observe that the most recent episode of uplift at Long Valley began in mid-2011, continuing until late 2016, raising the surface by 100 mm in 6 years. The timing of the initiation of uplift coincides with the beginning of severe drought in California. Furthermore, the timing of a recent pause in uplift coincides with the very wet 2016-2017 winter, which saw approximately double normal snow pack. In prior studies, we showed that the timing of changes in geodetically measured uplift rate of the Sierra Nevada coincides with the timing of drought conditions in California, suggesting a link between hydrological loading and Sierra Nevada elevation. Here we take the analysis three steps further to show that changes in Sierra Nevada uplift rate coincide in time with 1) enhanced inflation at the Long Valley caldera, 2) shifts in the patterns and rates of horizontal tensor strain rate, and 3) seismicity patterns in the central Walker Lane. We use GPS solutions from the Nevada Geodetic Laboratory and the new GPS Imaging technique to produce robust animations of the time variable strain and uplift fields. The goals of this work are to document links between climate, Sierra Nevada uplift rates, response of the magmatic system, and seismicity in the Central Walker Lane, and to explore the physical mechanisms that may be behind these correlations.

39 CFR 776.3 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... buildings, structures and improvements. Contending site means a site or existing building for a proposed... saturated soil conditions. Wetlands generally include swamps, marshes, bogs, and similar areas. ...

Subtle shifts in microbial communities occur alongside the release of carbon induced by drought and rewetting in contrasting peatland ecosystems.

PubMed

Potter, Caitlin; Freeman, Chris; Golyshin, Peter N; Ackermann, Gail; Fenner, Nathalie; McDonald, James E; Ehbair, Abdassalam; Jones, Timothy G; Murphy, Loretta M; Creer, Simon

2017-09-12

Peat represents a globally significant pool of sequestered carbon. However, peatland carbon stocks are highly threatened by anthropogenic climate change, including drought, which leads to a large release of carbon dioxide. Although the enzymatic mechanisms underlying drought-driven carbon release are well documented, the effect of drought on peatland microbial communities has been little studied. Here, we carried out a replicated and controlled drought manipulation using intact peat 'mesocosm cores' taken from bog and fen habitats, and used a combination of community fingerprinting and sequencing of marker genes to identify community changes associated with drought. Community composition varied with habitat and depth. Moreover, community differences between mesocosm cores were stronger than the effect of the drought treatment, emphasising the importance of replication in microbial marker gene studies. While the effect of drought on the overall composition of prokaryotic and eukaryotic communities was weak, a subset of the microbial community did change in relative abundance, especially in the fen habitat at 5 cm depth. 'Drought-responsive' OTUs were disproportionately drawn from the phyla Bacteroidetes and Proteobacteria. Collectively, the data provide insights into the microbial community changes occurring alongside drought-driven carbon release from peatlands, and suggest a number of novel avenues for future research.

Refining soil organic carbon stock estimates for China’s palustrine wetlands

NASA Astrophysics Data System (ADS)

Ma, Kun; Liu, Junguo; Zhang, Ying; Parry, Lauren E.; Holden, Joseph; Ciais, Philippe

2015-12-01

Palustrine wetlands (PWs) include all bogs, fens, swamps and marshes that are non-saline and which are not lakes or rivers. They therefore form a highly important group of wetlands which hold large carbon stocks. If these wetlands are not protected properly they could become a net carbon source in the future. Compilation of spatially explicit wetland databases, national inventory data and in situ measurement of soil organic carbon (SOC) could be useful to better quantify SOC and formulate long-term strategies for mitigating global climate change. In this study, a synergistic mapping approach was used to create a hybrid map for PWs for China and to estimate their SOC content. Total SOC storage in PWs was estimated to be 4.3 ± 1.4 Pg C, with a SOC density of 31.17 (±10.55) kg C m-2 in the upper 1 m of the soil layer. This carbon stock is concentrated in Northeast China (49%) and the Qinghai-Tibet Plateau (41%). Given the large pool of carbon stored in PWs compared to other soil types, we suggest that urgent monitoring programmes on SOC should be established in regions with very few datasets, but where PWs appear to be common such as the Tibet region and Northwest China.

CH4 production via CO2 reduction in a temperate bog - A source of (C-13)-depleted CH4

NASA Technical Reports Server (NTRS)

Lansdown, J. M.; Quay, P. D.; King, S. L.

1992-01-01

The paper reports measurements, taken over two annual cycles, of the flux and delta(C-13) of CH4 released from an acidic peat bog located in the foothills of the Cascade Range in Washington state, U.S. Measurements of the rate of aceticlastic methanogenesis and CO2 reduction in peat soil, using (C-14)-labeled acetate and sodium bicarbonate, show that acetate was not an important CH4 precursor and that CO2 reduction could account for all of the CH4 production. The in situ kinetic isotope effect for CO2 reduction, calculated using the delta-(C-13) of soil water CO2 and CH4 flux, was 0.932 +/- 0.007.

Sombrero uplift above the Altiplano-Puna Magma Body: evidence of a ballooning mid-crustal diapir.

PubMed

Fialko, Yuri; Pearse, Jill

2012-10-12

The Altiplano-Puna ultralow-velocity zone in the central Andes, South America, is the largest active magma body in Earth's continental crust. Space geodetic observations reported an uplift in the Altiplano-Puna proper at a rate of ~10 mm/year; however, the nature of the inferred inflation source has been uncertain. We present data showing that the uplift has persisted at a nearly constant rate over the past two decades, and is surrounded by a broad zone of subsidence. We show that the ongoing uplift and peripheral subsidence may result from a large mid-crustal diapir fed by partial melt from the Altiplano-Puna Magma Body.

Respite Care, Stress, Uplifts, and Marital Quality in Parents of Children with Down Syndrome.

PubMed

Norton, Michelle; Dyches, Tina Taylor; Harper, James M; Roper, Susanne Olsen; Caldarella, Paul

2016-12-01

Parents of children with disabilities are at risk for high stress and low marital quality; therefore, this study surveyed couples (n = 112) of children with Down syndrome (n = 120), assessing whether respite hours, stress, and uplifts were related to marital quality. Structural equation modeling indicated that respite hours were negatively related to wife/husband stress, which was in turn negatively related to wife/husband marital quality. Also, wife uplifts were positively related to both wife and husband marital quality. Husband uplifts were positively related to husband marital quality. Therefore, it is important that respite care is provided and accessible to parents of children with Down syndrome.

Accelerating late Quaternary uplift of the New Georgia Island Group (Solomon island arc) in response to subduction of the recently active Woodlark spreading center and Coleman seamount

NASA Astrophysics Data System (ADS)

Mann, Paul; Taylor, Frederick W.; Lagoe, Martin B.; Quarles, Andrew; Burr, G.

1998-10-01

The New Georgia Island Group of the Solomon Islands is one of four places where an active or recently active spreading ridge has subducted beneath an island arc. We have used coral reef terraces, paleobathymetry of Neogene sedimentary rocks, and existing marine geophysical data to constrain patterns of regional Quaternary deformation related to subduction of the recently active Woodlark spreading center and its overlying Coleman seamount. These combined data indicate the following vertical tectonic history for the central part of the New Georgia Island Group: (1) subsidence of the forearc region (Tetepare and Rendova Islands) to water depths of ˜1500 m and deposition of marine turbidites until after 270 ka; (2) late Quaternary uplift of the forearc to sea level and erosion of an unconformity; (3) subsidence of the forearc to ˜500 m BSL and deposition of bathyal sediments; and (4) uplift of the forearc above sea level with Holocene uplift rates up to at least 7.5 mm/yr on Tetepare and 5 mm/yr on Rendova. In the northeastern part of the New Georgia Island Group, our combined data indicate a slightly different tectonic history characterized by lower-amplitude vertical motions and a more recent change from subsidence to uplift. Barrier reefs formed around New Georgia and Vangunu Islands as they subsided >300 m. By 50-100 ka, subsidence was replaced by uplift that accelerated to Holocene rates of ˜1 mm/yr on the volcanic arc compared with rates up to ˜7.5 mm/yr in the forearc area of Tetepare and Rendova. Uplift mechanisms, such as thermal effects due to subduction of spreading ridges, tectonic erosion, or underplating of deeply subducted bathymetric features, are not likely to function on the 270-ka period that these uplift events have occurred in the New Georgia Island Group. A more likely uplift mechanism for the post-270-ka accelerating uplift of the forearc and volcanic arc of the New Georgia Island Group is progressive impingement of the Coleman seamount or other topographically prominent features on the subducting plate. Regional effects we relate to this ongoing subduction-related process include: (1) late Quaternary (post-270 ka), accelerating uplift of the Rendova-Tetepare forearc area in response to initial impingement of the Coleman seamount followed by exponentially increasing collisional contact between the forearc and seamount; (2) later Quaternary propagation of uplift arcward to include the volcanic arc as the area of collisional contact between the forearc and seamount increased; and (3) large-wavelength folding that has produced regional variations in late Holocene uplift rates observed in both forearc (southern Rendova, Tetepare) and volcanic arc (New Georgia Island) areas. We propose that the dominant tectonic effect of Coleman seamount impingement is horizontal shortening of the forearc and arc crust that is produced by strong coupling between the subducting seamount and the unsedimented crystalline forearc of the New Georgia Island Group. The horizontal forces due to mechanical resistance to subducting rugged ridge and seamount topography may have terminated spreading of the Woodlark spreading center entering the trench (Ghizo ridge) and converted it to a presently active strike-slip fault zone.

Variable uplift rate through time: Holocene coral reef and neotectonics of Lutao, eastern Taiwan

NASA Astrophysics Data System (ADS)

Shen, Chuan-Chou; Wu, Chung-Che; Dai, Chang-Feng; Gong, Shou-Yeh

2018-05-01

Significant discrepancies have existed regarding rate and timing of the uplift of Lutao (Green Island), located at the border of the ongoing collision between the Eurasia continental plate and the Philippine Sea Plate. To document its neotectonic history, two cores were drilled into Holocene coral reefs exposed at the southeastern coast of Lutao. Twelve pristine fossil corals, nine taken from cores and three on the surface, were 230Th dated. The results show that the coral reefs started to develop at 8,736 ± 56 yr BP (before 1950 CE) with uplift rate varying from 3.6 mm/yr during 8.7-6.0 kyr BP to 1.2 mm/yr in the past six thousand years. Our study strongly suggests that the uplift rate can vary significantly on millennial time scale. Caution should be used when extrapolating uplift rate estimates based on Mid-late Holocene corals to early times for tectonic active locations, such as Lutao.

Present-day uplift of the western Alps.

PubMed

Nocquet, J-M; Sue, C; Walpersdorf, A; Tran, T; Lenôtre, N; Vernant, P; Cushing, M; Jouanne, F; Masson, F; Baize, S; Chéry, J; van der Beek, P A

2016-06-27

Collisional mountain belts grow as a consequence of continental plate convergence and eventually disappear under the combined effects of gravitational collapse and erosion. Using a decade of GPS data, we show that the western Alps are currently characterized by zero horizontal velocity boundary conditions, offering the opportunity to investigate orogen evolution at the time of cessation of plate convergence. We find no significant horizontal motion within the belt, but GPS and levelling measurements independently show a regional pattern of uplift reaching ~2.5 mm/yr in the northwestern Alps. Unless a low viscosity crustal root under the northwestern Alps locally enhances the vertical response to surface unloading, the summed effects of isostatic responses to erosion and glaciation explain at most 60% of the observed uplift rates. Rock-uplift rates corrected from transient glacial isostatic adjustment contributions likely exceed erosion rates in the northwestern Alps. In the absence of active convergence, the observed surface uplift must result from deep-seated processes.

Marine Terrace Deposits along the Mediterranean Coast on the Southeastern Turkey and Their Implications for Tectonic Uplift and Sea Level Change

NASA Astrophysics Data System (ADS)

Tari, U.; Tüysüz, O.; Blackwell, B. A. B.; Genç, Ş. C.; Florentin, J. A.; Mahmud, Z.; Li, G. L.; Blickstein, J. I. B.; Skinner, A. R.

2016-12-01

Tectonic movements among the African, Arabian and Anatolian Plates have deformed the eastern Mediterranean. These movements caused transtensional opening of the NE-trending Antakya Graben since the late Pliocene. Tectonic uplift coupled with Quaternary sealevel fluctuations has produced several stacked marine terraces along the Mediterranean coasts on the graben. Here, marine terrace deposits that sit on both flanks of the graben at elevations between 3 and 175 m were dated using electron spin resonance (ESR) method in order to calculate uplift rates. The ESR ages range from 12 ka in late MIS 2 to 457 ka in MIS 9-11, but most of the terraces contain molluscs reworked from several earlier deposits due to successive tectonic movements and sealevel fluctuations. By dating in situ fossils, along the basal contacts of the marine terraces, uplift rates were calculated on both sides of the Antakya Graben. Results indicate that these deposits were mainly uplifted by local active faults rather than regional movements.

Short-Term Uplift Rates and the Mountain Building Process in Southern Alaska

NASA Technical Reports Server (NTRS)

Sauber, Jeanne; Herring, Thomas A.; Meigs, Andrew; Meigs, Andrew

1998-01-01

We have used GPS at 10 stations in southern Alaska with three epochs of measurements to estimate short-term uplift rates. A number of great earthquakes as well as recent large earthquakes characterize the seismicity of the region this century. To reliably estimate uplift rates from GPS data, numerical models that included both the slip distribution in recent large earthquakes and the general slab geometry were constructed.

A lithospheric instability origin for Columbia River flood basalts and Wallowa Mountains uplift in northeast Oregon.

PubMed

Hales, T C; Abt, D L; Humphreys, E D; Roering, J J

2005-12-08

Flood basalts appear to form during the initiation of hotspot magmatism. The Columbia River basalts (CRB) represent the largest volume of flood basalts associated with the Yellowstone hotspot, yet their source appears to be in the vicinity of the Wallowa Mountains, about 500 km north of the projected hotspot track. These mountains are composed of a large granitic pluton intruded into a region of oceanic lithosphere affinity. The elevation of the interface between Columbia River basalts and other geological formations indicates that mild pre-eruptive subsidence took place in the Wallowa Mountains, followed by syn-eruptive uplift of several hundred metres and a long-term uplift of about 2 km. The mapped surface uplift mimics regional topography, with the Wallowa Mountains in the centre of a 'bull's eye' pattern of valleys and low-elevation mountains. Here we present the seismic velocity structure of the mantle underlying this region and erosion-corrected elevation maps of lava flows, and show that an area of reduced mantle melt content coincides with the 200-km-wide topographic uplift. We conclude that convective downwelling and detachment of a compositionally dense plutonic root can explain the timing and magnitude of Columbia River basalt magmatism, as well as the surface uplift and existence of the observed melt-depleted mantle.

Spatial and temporal uplift history of South America from calibrated drainage analysis

NASA Astrophysics Data System (ADS)

Rodríguez Tribaldos, V.; White, N. J.; Roberts, G. G.; Hoggard, M. J.

2017-06-01

A multidisciplinary approach is used to analyze the Cenozoic uplift history of South America. Residual depth anomalies of oceanic crust abutting this continent help to determine the pattern of present-day dynamic topography. Admittance analysis and crustal thickness measurements indicate that the elastic thickness of the Borborema and Altiplano regions is ≤10 km with evidence for sub-plate support at longer wavelengths. A drainage inventory of 1827 river profiles is assembled and used to investigate landscape development. Linear inverse modeling enables river profiles to be fitted as a function of the spatial and temporal history of regional uplift. Erosional parameters are calibrated using observations from the Borborema Plateau and tested against continent-wide stratigraphic and thermochronologic constraints. Our results predict that two phases of regional uplift of the Altiplano plateau occurred in Neogene times. Regional uplift of the southern Patagonian Andes also appears to have occurred in Early Miocene times. The consistency between observed and predicted histories for the Borborema, Altiplano, and Patagonian plateaux implies that drainage networks record coherent signals that are amenable to simple modeling strategies. Finally, the predicted pattern of incision across the Amazon catchment constrains solid sedimentary flux at the Foz do Amazonas. Observed and calculated flux estimates match, suggesting that erosion and deposition were triggered by regional Andean uplift during Miocene times.

Mechanical behaviour of the lithosphere beneath the Adamawa uplift (Cameroon, West Africa) based on gravity data

NASA Astrophysics Data System (ADS)

Poudjom Djomani, Y. H.; Diament, M.; Albouy, Y.

1992-07-01

The Adamawa massif in Central Cameroon is one of the African domal uplifts of volcanic origin. It is an elongated feature, 200 km wide. The gravity anomalies over the Adamawa uplift were studied to determine the mechanical behaviour of the lithosphere. Two approaches were used to analyse six gravity profiles that are 600 km long and that run perpendicular to the Adamawa trend. Firstly, the coherence function between topography and gravity was interpreted; secondly, source depth estimations by spectral analysis of the gravity data was performed. To get significant information for the interpretation of the experimental coherence function, the length of the profiles was varied from 320 km to 600 km. This treatment allows one to obtain numerical estimates of the coherence function. The coherence function analysis points out that the lithosphere is deflected and thin beneath the Adamawa uplift, and the Effective Elastic Thickness is of about 20 km. To fit the coherence, a load from below needs to be taken into account. This result on the Adamawa massif is of the same order of magnitude as those obtained on other African uplifts such as Hoggar, Darfur and Kenya domes. For the depth estimation, three major density contrasts were found: the shallowest depth (4-15 km) can be correlated to shear zone structures and the associated sedimentary basins beneath the uplift; the second density contrast (18-38 km) corresponds to the Moho; and finally, the last depth (70-90 km) would be the top of the upper mantle and demotes the low density zone beneath the Adamawa uplift.

Possible origin of the Bighorn uplift, WY, by lithospheric buckling during the Laramide orogeny

NASA Astrophysics Data System (ADS)

Tikoff, B.; Siddoway, C. S.; Worthington, L. L.; Anderson, M. L.

2017-12-01

The EarthScope Bighorn Project investigated the Bighorn uplift, Wyoming, a foreland structure developed during the 75-55 Ma Laramide orogeny. Any model for the Bighorn uplift must account for several geological and geophysical results from the EarthScope broadband and passive-active seismic study, the broader context provided by USArray, and legacy datasets: 1) The Moho is bulged up below portions of the surface exposure of the basement arch; 2) a high-velocity, high-density material (the "7.x layer") is absent in the lower crust beneath the arch culmination; 3) Shear wave splitting analysis shows distinct mantle fabrics on either side of the uplift; 4) Crustal thicknesses varied widely prior to the Laramide-age deformation; 5) A lack of reflectors associated with a regional decollement; 6) The Bighorn arch forms one in an array of low-amplitude, large-wavelength folds throughout the High Plains region. The uplift borders a NNW-trending (E-dipping?) geophysical anomaly inferred to be Proterozoic suture. A lithospheric buckling model offers a framework that accommodates most of the geological and geophysical data. Lithospheric buckling is the concept of low-amplitude, large-wavelength (150-350 km) lithospheric folding developed in response to an end-load, replicated in scaled physical models. A buckling instability focuses initial deformation, with faults developed in layered media/crustal section as shortening progresses. The strength/age of the mantle controls the fold wavelength, based on examples from multiple orogens (e.g. Urals, central Asia). Rarely does the geometry of the upward Moho deflection identically mirror the surface uplift in scaled models, nor does it in the Bighorn uplift, where fold localization is likely controlled by a pre-existing Proterozoic suture and/or mantle asperity. Indicated by shear wave SKS splitting data, distinct mantle fabrics on either side of the uplift extend into the lithospheric mantle, indicated the presence of a deep-rooted structure of a type that has not been incorporated in physical models.

Uplifting the Stable Crust of the Colorado Plateau through Crustal Hydration and Warming

NASA Astrophysics Data System (ADS)

Porter, R. C.; Holt, W. E.

2016-12-01

The Colorado Plateau (CP) is a high ( 2 km above sea level), low-relief, orogenic plateau located within the interior of the southwestern United States that presents several outstanding geologic questions, most notably about the timing and mechanism(s) for uplift. The CP was located below sea level during the Cretaceous and was uplifted to its modern elevation with little crustal shortening, making the cause of uplift enigmatic. Numerous mechanisms have been hypothesized to explain the uplift of this stable block and include delamination, mantle heating/phase changes, mantle convection, volatile addition, and various combinations of these. In order to better understand the crustal contribution to uplift, we utilize data from the EarthScope Transportable Array network to image the CP lithosphere and inform thermodynamic models of CP lower crustal composition. Rayleigh wave phase velocities calculated using ambient noise tomography and surface wave gradiometry were inverted for shear velocity resulting in a high-resolution velocity model of the CP crust and upper mantle. In order to provide greater context to these results, the thermodynamic modeling code Perple_X was utilized to forward model crustal densities, seismic velocities, and water content based on psuedosections calculated using published major element chemistry. Our seismic and modeling results show that uplift of the plateau is partially driven by hydration and extension of the lower crust, both of which reduce its density. Hydration of the CP crust likely occurred due to dewatering of the Farallon slab during flat-slab subduction and reduced lower crustal density by 70 kg/m3. Warming and extension further reduced the lower crustal density by 90 kg/m3 at the CP margins. Though these processes played a role in the uplift of the CP, additional mechanisms, likely due to mantle processes, are required to fully explain its high elevation. Additionally, hydration and subsequent dehydration may play an important role in the recent encroachment of deformation and volcanism into the interior of the CP.

Climatic vs. tectonic control on glacial relief

NASA Astrophysics Data System (ADS)

Prasicek, Günther; Herman, Frederic; Robl, Jörg

2017-04-01

The limiting effect of a climatically-induced glacial buzz-saw on the height of mountain ranges has been extensively discussed in the geosciences. The buzz-saw concept assumes that solely climate controls the amount of topography present above the equilibrium line altitude (ELA), while the rock uplift rate plays no relevant role. This view is supported by analyses of hypsometric patterns in orogens worldwide. Furthermore, numerical landscape evolution models show that glacial erosion modifies the hypsometry and reduces the overall relief of mountain landscapes. However, such models often do not incorporate tectonic uplift and can only simulate glacial erosion over a limited amount of time, typically one or several glacial cycles. Constraints on glacial end-member landscapes from analytical, time-independent models are widely lacking. Here we present a steady-state solution for a glacier equilibrium profile in an active orogen modified from the mathematical conception presented by Headley et al. (2012). Our approach combines a glacial erosion law with the shallow ice approximation, specifically the formulations of ice sliding and deformation velocities and ice flux, to calculate ice surface and bed topography from prescribed specific mass balance and rock uplift rate. This solution allows the application of both linear and non-linear erosion laws and can be iteratively fitted to a predefined gradient of specific mass balance with elevation. We tested the influence of climate (fixed rock uplift rate, different ELAs) and tectonic forcing (fixed ELA, different rock uplift rates) on steady-state relief. Our results show that, similar to fluvial orogens, both climate and rock uplift rate exert a strong influence on glacial relief and that the relation among rock uplift rate and relief is governed by the glacial erosion law. This finding can provide an explanation for the presence of high relief in high latitudes. Headley, R.M., Roe, G., Hallet, B., 2012. Glacier longitudinal profiles in regions of active uplift. Earth and Planetary Science Letters, 317-318, 354-362.

Modelling of oil spills in confined maritime basins: The case for early response in the Eastern Mediterranean Sea.

PubMed

Alves, Tiago M; Kokinou, Eleni; Zodiatis, George; Lardner, Robin; Panagiotakis, Costas; Radhakrishnan, Hari

2015-11-01

Oil spill models are combined with bathymetric, meteorological, oceanographic, and geomorphological data to model a series of oil spill accidents in the Eastern Mediterranean Sea. A total of 104 oil spill simulations, computed for 11 different locations in the Levantine Basin, show that oil slicks will reach the coast of Cyprus in four (4) to seven (7) days in summer conditions. Oil slick trajectories are controlled by prevailing winds and current eddies. Based on these results, we support the use of chemical dispersants in the very few hours after large accidental oil spills. As a corollary, we show shoreline susceptibility to vary depending on: a) differences in coastline morphology and exposure to wave action, b) the existence of uplifted wave-cut platforms, coastal lagoons and pools, and c) the presence of tourist and protected environmental areas. Mitigation work should take into account the relatively high susceptibility of parts of the Eastern Mediterranean. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Life in Ice: Microbial Growth Dynamics and Greenhouse Gas Production During Winter in a Thermokarst Bog Revealed by Stable Isotope Probing Targeted Metagenomics

NASA Astrophysics Data System (ADS)

Blazewicz, S.; White, R. A., III; Tas, N.; Euskirchen, E. S.; Mcfarland, J. W.; Jansson, J.; Waldrop, M. P.

2016-12-01

Permafrost contains a reservoir of frozen C estimated to be twice the size of the current atmospheric C pool. In response to changing climate, permafrost is rapidly warming which could result in widespread seasonal thawing. When permafrost thaws, soils that are rich in ice and C often transform into thermokarst wetlands with anaerobic conditions and significant production of atmospheric CH4. While most C flux research in recently thawed permafrost concentrates on the few summer months when seasonal thaw has occurred, there is mounting evidence that sizeable portions of annual CO2 and CH4 efflux occurs over winter or during a rapid burst of emissions associated with seasonal thaw. A potential mechanism for such efflux patterns is microbial activity in frozen soils over winter where gasses produced are partially trapped within ice until spring thaw. In order to better understand microbial transformation of soil C to greenhouse gas over winter, we applied stable isotope probing (SIP) targeted metagenomics combined with process measurements and field flux data to reveal activities of microbial communities in `frozen' soil from an Alaskan thermokarst bog. Field studies revealed build-up of CO2 and CH4 in frozen soils suggesting that microbial activity persisted throughout the winter in soils poised just below the freezing point. Laboratory incubations designed to simulate in-situ winter conditions (-1.5 °C and anaerobic) revealed continuous CH4 and CO2 production. Strikingly, the quantity of CH4 produced in 6 months in frozen soil was equivalent to approximately 80% of CH4 emitted during the 3 month summer `active' season. Heavy water SIP targeted iTag sequencing revealed growing bacteria and archaea in the frozen anaerobic soil. Growth was primarily observed in two bacterial phyla, Firmicutes and Bacteroidetes, suggesting that fermentation was likely the major C mineralization pathway. SIP targeted metagenomics facilitated characterization of the primary metabolic pathways in growing organisms that likely drove C mineralization. Results indicate that winter microbial activities can play an important role in controlling seasonal C flux in recent thawed permafrost and characterization of growing organisms leads to stronger mechanistic linkages between the soil microbial community and ecosystem processes.

Drainage Analysis of the South American Landscape and its Tectonic Implications

NASA Astrophysics Data System (ADS)

Rodríguez Tribaldos, Verónica; White, Nicholas J.; Roberts, Gareth G.

2016-04-01

The majority of studies aimed at investigating topographic growth and landscape evolution have limited spatial coverage. Frequently, spot measurements of uplift and denudation are only available, which hampers spatial resolution of the growth of regional topographic features. This limitation can be overcome by quantitatively analysing substantial, continent-wide, drainage networks. The shapes of long wavelength longitudinal river profiles appear to be mainly controlled by regional uplift and moderated by erosional processes, both of which can vary as a function of space and time. By parametrizing erosional histories, it is feasible to develop inverse models that permit spatial and temporal patterns of regional uplift to be reliably retrieved. Here, a drainage inventory for South America consisting of 1827 rivers has been inverted. River profiles were extracted from the SRTM topographic dataset and modelled using a simplified version of the stream-power law, in which erosional processes are described using a linear advective formulation. The inverse problem is then solved by seeking smooth uplift rate histories that minimize the misfit between observed and calculated river profiles using a linearized, damped, non-negative, least squares algorithm. Calibration of erosional processes is achieved by inverting the complete drainage inventory and seeking a calculated uplift history that best honours independent geological observations from the Borborema Province of northeast Brazil. This province experienced regional Cenozoic uplift. Calculated uplift rate histories for South America suggest that the bulk of its topography developed during Cenozoic times. The model suggests, for instance, that the Andean mountain chain mostly arose in late Eocene-Oligocene (i.e. 40-28 Ma) times with an increase in elevation during Miocene times (i.e. the last 20 Ma). Uplift of the Central Andean Altiplano from an elevation of ~ 1 km to its present-day height of ~ 4 km occurred within the last 25-30 Ma. Our results are consistent with a wide range of independent geological observations across South America (e.g. elevated marine deposits, thermochronology, paleoelevation estimates from paleobotany, standard/clumped isotopes analyses). Finally, an important test of our thesis concerns offshore sedimentary flux. For example, our calculated uplift history can be used to predict the history of sedimentary flux into the Foz do Amazonas basin. This prediction agrees with offshore studies of the Amazon delta which suggest a rapid increase in clastic deposition since middle Miocene times. In summary, we propose that South American drainage contains useful information about spatial and temporal patterns of regional uplift which can help our understanding of regional topographic growth and landscape evolution.

Deconvolving regional and fault-driven uplift in Calabria using drainage inversion techniques and field observations

NASA Astrophysics Data System (ADS)

Quye-Sawyer, Jennifer; Whittaker, Alexander; Roberts, Gareth; Rood, Dylan

2017-04-01

A key challenge in the Earth Sciences is to understand the timing and extent of the coupling between geodynamics, tectonics, and surface processes. In principle, the landscape adjusts to surface uplift or tectonic events, and present-day topography records a convolution of these processes. The inverse problem, the ability to find the 'best fit' theoretical scenario to match present day observations, is particularly desirable as it makes use of real data, encompasses the complexity of natural systems and quantifies model uncertainty through misfit. The region of Calabria, Italy, is known to have experienced geologically rapid uplift ( 1 mm/yr) since the Early Pleistocene, inferred from widespread marine terraces (ca. 1 Myr old) at elevations greater than 1 km. In addition, this is a tectonically active area of normal faulting with several highly destructive earthquakes in recent centuries. Since there has been some debate about the relative magnitudes of the uplift caused by regional processes or by faulting, the ability to model these effects on a regional scale may help resolve this problem. Therefore, Calabria is both a suitable and important site to model large magnitude recent geomorphic change. 1368 river longitudinal profiles have been generated from satellite digital elevation models (DEMs). These longitudinal profiles were compared to aerial photography to confirm the accuracy of this automated process. The longitudinal profiles contain numerous non-lithologically controlled knickpoints. Field observations support the presence of knickpoints extracted from the DEM and measurements of pebble imbrication from fluvial terraces suggest the planform stability of the drainage network in the last 1 Myr. By assuming fluvial erosion obeys stream power laws with an exponent of upstream area of 0.5 ± 0.1, the evolution of the landscape is computed using a linearized joint inversion of the longitudinal profiles. This has produced a spatially and temporally continuous model of cumulative uplift for the Calabria region. We have used independently-collated stratigraphic data to provide absolute ages for the inversion model. In particular, uplift rates of well-dated marine terraces constrain the inversion near the coastline and we are using cosmogenic isotope isochron burial dating to refine the timing of the onset of uplift. Preliminary inversion results show the initiation of uplift at approximately 1.9 Ma. The model output is consistent with field observations of regional uplift, later combined with fault related extension. Furthermore, these results are consistent with an increase in regional uplift rate prior to fault initiation.

Aseismic uplift in California

USGS Publications Warehouse

Castle, Robert O.; Elliot, Michael R.; Gilmore, Thomas D.; Mark, Robert K.; Newman, Evelyn B.; Tinsley, John C.; Jackson, D.D.; Lee, W.B.; Liu, C.-C.

1981-01-01

We disagree with several of the arguments cited by Jackson et al. in support of their view that "the inference of wide-spread aseismic uplift in southern California is not justified" (1). Specifically, the striking correlation shown in figure 1 of Jackson et al. (1) is an artifact of the construction, the rod calibration data are atypical, the cited regression techniques are of doubtful value, and the geologically and geodetically determined uplift rates are inappropriately compared.

A multiproxy study of Holocene water-depth and environmental changes in Lake St Ana, Eastern Carpathian Mountains, Romania

NASA Astrophysics Data System (ADS)

Magyari, E. K.; Buczkó, K.; Braun, M.; Jakab, G.

2009-04-01

This study presents the results of a multi-disciplinary investigation carried out on the sediment of a crater lake (Lake Saint Ana, 950 m a.s.l.) from the Eastern Carpathian Mountains. The lake is set in a base-poor volcanic environment with oligotrophic and slightly acidic water. Loss-on-ignition, major and trace element, pollen, plant macrofossil and siliceous algae analyses were used to reconstruct Holocene environmental and water-depth changes. Diatom-based transfer functions were applied to estimate the lake's trophic status and pH, while reconstruction of the water-depth changes was based on the plant macrofossil and diatom records. The lowest Holocene water-depths were found between 9,000 and 7,400 calibrated BP years, when the crater was occupied by Sphagnum-bog and bog-pools. The major trend from 7,400 years BP was a gradual increase, but the basin was still dominated by poor-fen and poor fen-pools. Significant increases in water-depth, and meso/oligotrophic lake conditions were found from 5,350(1), 3,300(2) and 2,700 years BP. Of these, the first two coincided with major terrestrial vegetation changes, namely the establishment of Carpinus betulus on the crater slope (1), and the replacement of the lakeshore Picea abies forest by Fagus sylvatica (2). The chemical record clearly indicated significant soil changes along with the canopy changes (from coniferous to deciduous), that in turn led to increased in-lake productivity and pH. A further increase in water-depth around 2,700 years BP resulted in stable thermal stratification and hypolimnetic anoxia that via P-release further increased in-lake productivity and eventually led to phytoplankton blooms with large populations of Scenedesmus cf. S. brasiliensis. High productivity was depressed by anthropogenic lakeshore forest clearances commencing from ca. 1,000 years BP that led to the re-establishment of Picea abies on the lakeshore and consequent acidification of the lake-water. On the whole, these data allow the following main inference to be made: Lake Saint Ana is a vulnerable ecosystem; hydrological, biological and chemical processes in the lake are heavily influenced by the lakeshore forest and the soil underlying it. In-lake productivity is higher under deciduous canopy and litter, and considerably repressed by coniferous canopy and litter. The lake today subsists in a managed environment, that is however far from its natural state. This would be a dense Fagus sylvatica forest supplying more nutrients and keeping up a more productive in-lake flora and fauna. An overview of the regional Holocene lake-level records suggests that the general lake-level trends of this study agree with other records in the region, except for the lat 2,700 years, for which conflicting trends were found. The pollen based palaeo-precipitation record in NW Romania signals lower precipitation, while our, and some other records, signal significant increase in available moisture. Further studies are needed to resolve this problem.

Contrasting species-environment relationships in communities of testate amoebae, bryophytes and vascular plants along the fen-bog gradient.

PubMed

Lamentowicz, Mariusz; Lamentowicz, Lukasz; van der Knaap, Willem O; Gabka, Maciej; Mitchell, Edward A D

2010-04-01

We studied the vegetation, testate amoebae and abiotic variables (depth of the water table, pH, electrical conductivity, Ca and Mg concentrations of water extracted from mosses) along the bog to extremely rich fen gradient in sub-alpine peatlands of the Upper Engadine (Swiss Alps). Testate amoeba diversity was correlated to that of mosses but not of vascular plants. Diversity peaked in rich fen for testate amoebae and in extremely rich fen for mosses, while for testate amoebae and mosses it was lowest in bog but for vascular plants in extremely rich fen. Multiple factor and redundancy analyses (RDA) revealed a stronger correlation of testate amoebae than of vegetation to water table and hydrochemical variables and relatively strong correlation between testate amoeba and moss community data. In RDA, hydrochemical variables explained a higher proportion of the testate amoeba and moss data than water table depth. Abiotic variables explained a higher percentage of the species data for testate amoebae (30.3% or 19.5% for binary data) than for mosses (13.4%) and vascular plants (10%). These results show that (1) vascular plant, moss and testate amoeba communities respond differently to ecological gradients in peatlands and (2) testate amoebae are more strongly related than vascular plants to the abiotic factors at the mire surface. These differences are related to vertical trophic gradients and associated niche differentiation.

Development of the mixed conifer forest in northern New Mexico and its relationship to Holocene environmental change

NASA Astrophysics Data System (ADS)

Anderson, R. Scott; Jass, Renata B.; Toney, Jaime L.; Allen, Craig D.; Cisneros-Dozal, Luz M.; Hess, Marcey; Heikoop, Jeff; Fessenden, Julianna

2008-03-01

Chihuahueños Bog (2925 m) in the Jemez Mountains of northern New Mexico contains one of the few records of late-glacial and postglacial development of the mixed conifer forest in southwestern North America. The Chihuahueños Bog record extends to over 15,000 cal yr BP. An Artemisia steppe, then an open Picea woodland grew around a small pond until ca. 11,700 cal yr BP when Pinus ponderosa became established. C/N ratios, δ13C and δ15N values indicate both terrestrial and aquatic organic matter was incorporated into the sediment. Higher percentages of aquatic algae and elevated C/N ratios indicate higher lake levels at the opening of the Holocene, but a wetland developed subsequently as climate warmed. From ca. 8500 to 6400 cal yr BP the pond desiccated in what must have been the driest period of the Holocene there. C/N ratios declined to their lowest Holocene levels, indicating intense decomposition in the sediment. Wetter conditions returned after 6400 cal yr BP, with conversion of the site to a sedge bog as groundwater levels rose. Higher charcoal influx rates after 6400 cal yr BP probably result from greater biomass production rates. Only minor shifts in the overstory species occurred during the Holocene, suggesting that mixed conifer forest dominated throughout the record.

A Mycoplasma species of Emydidae turtles in the northeastern USA.

PubMed

Ossiboff, Robert J; Raphael, Bonnie L; Ammazzalorso, Alyssa D; Seimon, Tracie A; Niederriter, Holly; Zarate, Brian; Newton, Alisa L; McAloose, Denise

2015-04-01

Mycoplasma infections can cause significant morbidity and mortality in captive and wild chelonians. As part of a health assessment of endangered bog turtles (Glyptemys muhlenbergii) in the northeastern US, choanal and cloacal swabs from these and other sympatric species, including spotted turtles (Clemmys guttata), eastern box turtles (Terrapene carolina carolina), wood turtles (Glyptemys insculpta), and common snapping turtles (Chelydra serpentina) from 10 sampling sites in the states (US) of Delaware, New Jersey, and Pennsylvania, were tested by PCR for Mycoplasma. Of 108 turtles tested, 63 (58.3%) were PCR positive for Mycoplasma including 58 of 83 bog turtles (70%), three of three (100%) eastern box turtles, and two of 11 (18%) spotted turtles; all snapping turtles (n = 7) and wood turtles (n = 4) were negative. Sequence analysis of portions of the 16S-23S intergenic spacer region and the 16S ribosomal RNA gene revealed a single, unclassified species of Mycoplasma that has been previously reported in eastern box turtles, ornate box turtles (Terrapene ornata ornata), western pond turtles (Emys marmorata), and red-eared sliders (Trachemys scripta elegans). We document a high incidence of Mycoplasma, in the absence of clinical disease, in wild emydid turtles. These findings, along with wide distribution of the identified Mycoplasma sp. across a broad geographic region, suggest this bacterium is likely a commensal inhabitant of bog turtles, and possibly other species of emydid turtles, in the northeastern US.

Sphagnum Moss as an Indicator of Contemporary Rates of Atmospheric Dust Deposition in the Athabasca Bituminous Sands Region.

PubMed

Mullan-Boudreau, Gillian; Belland, Rene; Devito, Kevin; Noernberg, Tommy; Pelletier, Rick; Shotyk, William

2017-07-05

Sphagnum moss was collected from ombrotrophic (rain-fed) peat bogs to quantify dust emissions from the open-pit mining and upgrading of Athabasca bituminous sands (ABS). A total of 30 bogs were sampled in the ABS region, and 5 were sampled in central Alberta. Ash was separated into the acid-insoluble ash (AIA) and acid-soluble ash (ASA) fractions using HCl. The AIA concentrations increase toward industry from 0.4 ± 0.5% to 4.7 ± 2.0% over a distance of 30 km; the control site at the Utikuma Region Study Area (URSA) yielded 0.29 ± 0.07% (n = 30). Mass accumulations rates showed similar spatial variation. The morphology and mineralogy of the AIA particles were studied using scanning electron microscopy and energy-dispersive X-ray analysis and the particle size distributions using optical methods. Particle size was more variable in moss closer to industry. Major ions in the ASA fraction showed elevated accumulation rates of Ca, K, Fe, Mg, P, and S, with P being up to 5 times greater in samples nearest industry compared to those in distal locations. Given that P has been regarded as the growth-limiting nutrient in bogs, fertilization of nutrient-poor ecosystems, such as these from fugitive emissions of dusts from open-pit mining, may have long-term ecological ramifications.

High specificity but contrasting biodiversity of Sphagnum-associated bacterial and plant communities in bog ecosystems independent of the geographical region.

PubMed

Opelt, Katja; Berg, Christian; Schönmann, Susan; Eberl, Leo; Berg, Gabriele

2007-10-01

Mosses represent ecological niches that harbor a hitherto largely uncharacterized microbial diversity. To investigate which factors affect the biodiversity of bryophyte-associated bacteria, we analyzed the bacterial communities associated with two moss species, which exhibit different ecological behaviors and importance in bog ecosystems, Sphagnum magellanicum and Sphagnum fallax, from six temperate and boreal bogs in Germany and Norway. Furthermore, their surrounding plant communities were studied. Molecular analysis of bacterial communities was determined by single-strand conformation polymorphism (SSCP) analysis using eubacterial and genus-specific primers for the dominant genera Burkholderia and Serratia as well as by sequence analysis of a Burkholderia 16S rRNA gene clone library. Plant communities were analyzed by monitoring the abundance and composition of bryophyte and vascular plant species, and by determining ecological indicator values. Interestingly, we found a high degree of host specificity for associated bacterial and plant communities of both Sphagnum species independent of the geographical region. Calculation of diversity indices on the basis of SSCP gels showed that the S. fallax-associated communities displayed a statistically significant higher degree of diversity than those associated with S. magellanicum. In contrast, analyses of plant communities of Sphagnum-specific habitats resulted in a higher diversity of S. magellanicum-specific habitats for all six sites. The higher content of nutrients in the S. fallax-associated ecosystems can explain higher diversity of microorganisms.

Sphagnum mosses from 21 ombrotrophic bogs in the athabasca bituminous sands region show no significant atmospheric contamination of "heavy metals".

PubMed

Shotyk, William; Belland, Rene; Duke, John; Kempter, Heike; Krachler, Michael; Noernberg, Tommy; Pelletier, Rick; Vile, Melanie A; Wieder, Kelman; Zaccone, Claudio; Zhang, Shuangquan

2014-11-04

Sphagnum moss was collected from 21 ombrotrophic (rain-fed) peat bogs surrounding open pit mines and upgrading facilities of Athabasca bituminous sands in Alberta (AB). In comparison to contemporary Sphagnum moss from four bogs in rural locations of southern Germany (DE), the AB mosses yielded lower concentrations of Ag, Cd, Ni, Pb, Sb, and Tl, similar concentrations of Mo, but greater concentrations of Ba, Th, and V. Except for V, in comparison to the "cleanest", ancient peat samples ever tested from the northern hemisphere (ca. 6000-9000 years old), the concentrations of each of these metals in the AB mosses are within a factor of 3 of "natural, background" values. The concentrations of "heavy metals" in the mosses, however, are proportional to the concentration of Th (a conservative, lithophile element) and, therefore, contributed to the plants primarily in the form of mineral dust particles. Vanadium, the single most abundant trace metal in bitumen, is the only anomaly: in the AB mosses, V exceeds that of ancient peat by a factor of 6; it is therefore enriched in the mosses, relative to Th, by a factor of 2. In comparison to the surface layer of peat cores collected in recent years from across Canada, from British Columbia to New Brunswick, the Pb concentrations in the mosses from AB are far lower.

Holocene climate variability revealed by oxygen isotope analysis of Sphagnum cellulose from Walton Moss, northern England

NASA Astrophysics Data System (ADS)

Daley, T. J.; Barber, K. E.; Street-Perrott, F. A.; Loader, N. J.; Marshall, J. D.; Crowley, S. F.; Fisher, E. H.

2010-07-01

Stable isotope analyses of Sphagnum alpha-cellulose, precipitation and bog water from three sites across northwestern Europe (Raheenmore, Ireland, Walton Moss, northern England and Dosenmoor, northern Germany) over a total period of 26 months were used to investigate the nature of the climatic signal recorded by Sphagnum moss. The δ18O values of modern alpha-cellulose tracked precipitation more closely than bog water, with a mean isotopic fractionation factor αcellulose-precipitation of 1.0274 ± 0.001 (1 σ) (≈27‰). Sub-samples of isolated Sphagnum alpha-cellulose were subsequently analysed from core WLM22, Walton Moss, northern England yielding a Sphagnum-specific isotope record spanning the last 4300 years. The palaeo-record, calibrated using the modern data, provides evidence for large amplitude variations in the estimated oxygen isotope composition of precipitation during the mid- to late Holocene. Estimates of palaeotemperature change derived from statistical relationships between modern surface air temperatures and δ18O precipitation values for the British Isles give unrealistically large variation in comparison to proxies from other archives. We conclude that use of such relationships to calibrate mid-latitude palaeo-data must be undertaken with caution. The δ18O record from Sphagnum cellulose was highly correlated with a palaeoecologically-derived index of bog surface wetness (BSW), suggesting a common climatic driver.

Vulnerability of the peatland carbon sink to sea-level rise

PubMed Central

Whittle, Alex; Gallego-Sala, Angela V.

2016-01-01

Freshwater peatlands are carbon accumulating ecosystems where primary production exceeds organic matter decomposition rates in the soil, and therefore perform an important sink function in global carbon cycling. Typical peatland plant and microbial communities are adapted to the waterlogged, often acidic and low nutrient conditions that characterise them. Peatlands in coastal locations receive inputs of oceanic base cations that shift conditions from the environmental optimum of these communities altering the carbon balance. Blanket bogs are one such type of peatlands occurring in hyperoceanic regions. Using a blanket bog to coastal marsh transect in Northwest Scotland we assess the impacts of salt intrusion on carbon accumulation rates. A threshold concentration of salt input, caused by inundation, exists corresponding to rapid acidophilic to halophilic plant community change and a carbon accumulation decline. For the first time, we map areas of blanket bog vulnerable to sea-level rise, estimating that this equates to ~7.4% of the total extent and a 0.22 Tg yr−1 carbon sink. Globally, tropical peatlands face the proportionally greatest risk with ~61,000 km2 (~16.6% of total) lying ≤5 m elevation. In total an estimated 20.2 ± 2.5 GtC is stored in peatlands ≤5 m above sea level, which are potentially vulnerable to inundation. PMID:27354088

Cirque glacier on South Georgia shows centennial variability over the last 7000 years

NASA Astrophysics Data System (ADS)

Oppedal, Lea T.; Bakke, Jostein; Paasche, Øyvind; Werner, Johannes P.; van der Bilt, Willem G. M.

2018-02-01

A 7000 year-long cirque glacier reconstruction from South Georgia, based on detailed analysis of fine-grained sediments deposited downstream in a bog and a lake, suggests continued presence during most of the Holocene. Glacier activity is inferred from various sedimentary properties including magnetic susceptibility (MS), dry bulk density (DBD), loss-on-ignition (LOI) and geochemical elements (XRF), and tallied to a set of terminal moraines. The two independently dated sediment records document concurring events of enhanced glacigenic sediment influx to the bog and lake, whereas the upstream moraines afford the opportunity to calculate past Equilibrium Line Altitudes (ELA) which has varied in the order of 70 m altitude. Combined, the records provide new evidence of cirque glacier fluctuations on South Georgia. Based on the onset of peat formation, the study site was deglaciated prior to 9900±250 years ago when Neumayer tidewater glacier retreated up-fjord. Changes in the lake and bog sediment properties indicate that the cirque glacier was close to its maximum Holocene extent between 7200±400 and 4800±200 cal BP, 2700±150 and 2000±200 cal BP, 500±150-300±100 cal BP, and in the 20th century (likely 1930s). The glacier fluctuations are largely in-phase with reconstructed Patagonian glaciers, implying that they respond to centennial climate variability possibly connected to corresponding modulations of the Southern Westerly Winds.

Development of the mixed conifer forest in northern New Mexico and its relationship to Holocene environmental change

USGS Publications Warehouse

Anderson, R. Scott; Jass, R.B.; Toney, J.L.; Allen, Craig D.; Cisneros-Dozal, L. M.; Hess, M.; Heikoop, Jeff; Fessenden, J.

2008-01-01

Chihuahueños Bog (2925 m) in the Jemez Mountains of northern New Mexico contains one of the few records of late-glacial and postglacial development of the mixed conifer forest in southwestern North America. The Chihuahueños Bog record extends to over 15,000 cal yr BP. AnArtemisiasteppe, then an openPiceawoodland grew around a small pond until ca. 11,700 cal yr BP whenPinus ponderosabecame established. C/N ratios,δ 13C andδ 15N values indicate both terrestrial and aquatic organic matter was incorporated into the sediment. Higher percentages of aquatic algae and elevated C/N ratios indicate higher lake levels at the opening of the Holocene, but a wetland developed subsequently as climate warmed. From ca. 8500 to 6400 cal yr BP the pond desiccated in what must have been the driest period of the Holocene there. C/N ratios declined to their lowest Holocene levels, indicating intense decomposition in the sediment. Wetter conditions returned after 6400 cal yr BP, with conversion of the site to a sedge bog as groundwater levels rose. Higher charcoal influx rates after 6400 cal yr BP probably result from greater biomass production rates. Only minor shifts in the overstory species occurred during the Holocene, suggesting that mixed conifer forest dominated throughout the record.

40 CFR 230.96 - Monitoring.

Code of Federal Regulations, 2010 CFR

2010-07-01

... required for aquatic resources with slow development rates (e.g., forested wetlands, bogs). Following..., and may include plans (such as as-built plans), maps, and photographs to illustrate site conditions...

33 CFR 332.6 - Monitoring.

Code of Federal Regulations, 2010 CFR

2010-07-01

...., forested wetlands, bogs). Following project implementation, the district engineer may reduce or waive the... performance standards, and may include plans (such as as-built plans), maps, and photographs to illustrate...

40 CFR 503.9 - General definitions.

Code of Federal Regulations, 2013 CFR

2013-07-01

... site. (t) Pollutant is an organic substance, an inorganic substance, a combination of organic and... typically adapted for life in saturated soil conditions. Wetlands generally include swamps, marshes, bogs...

40 CFR 503.9 - General definitions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... site. (t) Pollutant is an organic substance, an inorganic substance, a combination of organic and... typically adapted for life in saturated soil conditions. Wetlands generally include swamps, marshes, bogs...

40 CFR 503.9 - General definitions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... site. (t) Pollutant is an organic substance, an inorganic substance, a combination of organic and... typically adapted for life in saturated soil conditions. Wetlands generally include swamps, marshes, bogs...

40 CFR 503.9 - General definitions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... site. (t) Pollutant is an organic substance, an inorganic substance, a combination of organic and... typically adapted for life in saturated soil conditions. Wetlands generally include swamps, marshes, bogs...

Late Cenozoic Colorado River Incision and Implications for Neogene Uplift of the Colorado Rockies

NASA Astrophysics Data System (ADS)

Aslan, A.; Karlstrom, K. E.; Kirby, E.; Heizler, M. T.

2012-12-01

Basalt flows and volcanic ashes serve as a datum for calculating post-10 Ma river incision rates in western Colorado. The main picture that emerges from the data is one of regional variability of incision rates, which we hypothesize to reflect differential uplift of the Colorado Rockies during the Neogene. Maximum rates (90-180 m/Ma) and magnitudes (750-1500 m) of river incision are recorded between Grand Mesa and Glenwood Canyon, and in the Flat Tops. Minimum rates (<30 m/Ma) and magnitudes (<250 m) of river incision are associated post-Laramide normal faults within the Browns Park-Sand Wash basin in northwestern Colorado and in Middle Park of north-central Colorado. Differential uplift of the Colorado Rockies during the late Cenozoic can be inferred by comparing incision rates and magnitudes at locations upstream and downstream of knickzones. Along the Colorado River, post-10 Ma incision rates and magnitudes incision remain fairly constant (rates >100 m/Ma; magnitudes >1000 m) from Grand Mesa upstream to Gore Canyon, and then decrease markedly in Middle Park (rates <10 m/Ma; magnitudes <100 m) across the Gore Canyon knickzone. Normal-faulting of ca. 10 Ma deposits in Middle Park shows that incision rate variations partly reflect late Cenozoic faulting. Along the Yampa River, post-10 Ma incision rates and magnitudes are low (rates 15-27 m/Ma; magnitudes < 230 m) immediately upstream of Yampa Canyon, and then increase significantly (rates 96-132 m/Ma; magnitudes ~1250 m) upstream near the headwaters. We interpret this upstream increase in river incision rate and magnitude to reflect Neogene uplift of the Yampa River headwaters relative to its lower reaches. Lastly, differential late Cenozoic uplift of the Colorado Rockies is suggested by differences in the timing of regional exhumation and river incision within different drainage basins. Colorado River incision and regional exhumation occurred between 9.8 and 7.8 Ma. In contrast, Yampa River incision began between 8 and 6 Ma. Because incision in both the Colorado and Yampa River systems began prior to integration of the Colorado River through Grand Canyon, it is plausible that differences in the timing of river incision in the upper Colorado Basin are related to Neogene differential uplift. Assuming river incision and rock uplift magnitudes are subequal, flexural isostatic modeling suggests that isostatic adjustments account for only 33-50% of the post-10 Ma rock uplift recorded in western Colorado, and that there has been 0.75 to 1.0 km of post-10 Ma epeirogenic rock uplift. Areas with the largest magnitudes of post-10 Ma rock uplift generally overlie areas of basaltic magmatism and anomalously low mantle P-wave velocities. We support the hypothesis that mantle buoyancy has produced 0.75-1.0 km of Neogene uplift of the Colorado Rockies.

Evidence of Himalayan uplift as seen in Neogene records of Indian monsoon variability from ODP Hole 722B, NW Arabian Sea

NASA Astrophysics Data System (ADS)

Muthusamy, Prakasam; Gupta, Anil K.; Saini, Naresh K.

2013-04-01

The Indian monsoon is one of the most interesting climatic features on Earth impacting most populous countries of South and East Asia. It is marked by seasonal reversals of wind direction with southwesterly winds in summer (June-September) and northeasterly winds in winter (December-February). The monsoon not only impacts socioeconomic conditions of Asia but also brings important changes in fauna and flora, ocean upwelling and primary productivity in the Arabian Sea. The Himalaya has undergone several phases of rapid uplift and exhumation since the early Miocene which led to major intensification of the Indian monsoon. The monsoon is driven by the thermal contrast between land and sea, and is intimately linked with the latitudinal movement of the Inter-Tropical Convergence Zone (ITCZ). The effect of Indian monsoon variability and the Himalayan uplift can be seen in numerous proxy records across the region. In this study we discussed about the Indian monsoon intensification and the Himalayan uplift since the early Miocene based on multi proxy records such as planktic foraminiferal relative abundances (Globigerina bulloides, Globigerinita glutinata and mixed layer species), total organic carbon (TOC), CaCO3 and elemental data from ODP Hole 722B (2028 mbsf), northwestern Arabian Sea. The TOC, CaCO3 and elemental variations of the ODP Hole 722B suggest multi phase of monsoonal intensification and Himalayan uplifts. Our results suggest that in the early Miocene (23.03 Ma) to ~15Ma, the wind strength and productivity were low. A major change is observed at ~15 Ma, during which time numerous proxies show abrupt changes. TOC, CaCO3 and Elemental analyses results reveal that a major change in the productivity, wind strength and chemical weathering starts around 15 Ma and extends up to 10 Ma. This suggests that a major Himalayan uplift occurred during ~15-10 Ma that drove Indian monsoon intensification. A similar change is also observed during 5 to 1 Ma. These long-term paleoclimatic trends correlated to Himalayan uplift. Major peaks in various proxy records correspond with enhanced monsoonal strength and the Himalayan uplift. Keywords: Indian monsoon; Himalayan uplift; Arabian Sea; Productivity; Planktic foraminifera; Total Organic Carbon

Uplifted Terraces along the Southeastern Coast of Bangladesh Reveal the Extent of 1762 Earthquake Surface Deformation and Potentially Document Prior Earthquakes

NASA Astrophysics Data System (ADS)

Mondal, D. R.; McHugh, C.; Steckler, M. S.; Seeber, L.; Akhter, S. H.; Mustaque, S.; Knappett, P. S.

2016-12-01

To better understand geohazards for Bangladesh, the surface expression of the 1762 earthquake and previous earthquakes, we surveyed the coast of Teknaf for evidence of uplift with high precision NetR9, RTX GPS. Previous studies by Aung et al. (2006; 2008) and Wang et al. (2013) documented uplifted terraces along the west coast of Myanmar and linked the youngest terrace to the 1762 Arakan earthquake. Previous studies by Mondal et al. (2015) documented 2.5 m uplifted microatoll corals in the Saint Martin anticline, 10 km southwest from the Teknaf coastline, and linked their uplift by U/Th ages to the 1762 earthquake. Along the southeast Bangladesh coastline, we mapped three geomorphic terraces for 70 km from Teknaf to Cox's Bazar. While GPS measured the location and elevation, an optical level (Theodolite) was used to survey across the different terraces from the beach to the Teknaf anticline foothills. The terraces were also characterized by slope analysis using 30 m SRTM DEM to understand the relation between the terrace geomorphology and potential influence from slope aprons derived from the erosion of the anticline. Our results show that the elevation of three terraces is consistent along the coast, and that terrace elevation ranges from 2-5 m, 5 -7 m and 11-13 m for the youngest, intermediate and oldest terrace, respectively. The youngest terrace, previously dated by McHugh et al. (2015) using C-14 from marine shells obtained from the terrace top, is linked to uplift from the 1762 earthquake. Marine fossils are present in the oldest terrace, and we will present the C-14 age results. Results also suggest that the higher terrace is not prominent in those locations where the slope of the anticline aprons is very high, and they are in a close proximity to each other. The present geomorphic evidence suggests that these terraces were uplifted by three paleoearthquakes, and C-14 ages will provide timing for the uplift. Evidence of terrace uplift derived from our GPS survey extends the 1762 surface deformation and megathrust rupture for at least 550 km along the Arakan segment of the Sunda subduction boundary.

Ice cap melting and low viscosity crustal root explain narrow geodetic uplift of the Western Alps

NASA Astrophysics Data System (ADS)

Chery, Jean; Genti, Manon; Vernant, Philippe

2016-04-01

More than 10 years of geodetic measurements demonstrate an uplift rate of 1-3 mm/yr of the high topography region of the Western Alps. By contrast, no significant horizontal motion has been detected. Three uplift mechanisms have been proposed so far: (1) the isostatic response to denudation. However this process is responsible for only a fraction of the observed uplift and (2) the rebound induced by the Wurmian ice cap melting. This process leads to a broader uplifting region than the one evidenced by geodetic observations. (3) a deep source motion associated with slab motion or some deep isostatic unbalance. Using a numerical model accounting for crustal and mantle rheology of the Alps and its foreland, we model the response to Wurmian ice cap melting. We show that a crustal viscosity contrast between the foreland and the central part of the Alps, the later being weaker with a viscosity of 1021 Pa.s, is needed to produce a narrow uplift. The vertical rates are enhanced if the strong uppermost mantle beneath the Moho is interrupted across the Alps, therefore allowing a weak vertical rheological anomaly thanks to the continuity between the low viscosity parts of the crust and mantle. References: Champagnac, J.-D., F. Schlunegger, K. Norton, F. von Blanckenburg, L. M. Abbühl, and M. Schwab (2009), Erosion-driven uplift of the modern Central Alps, Tectonophysics, 474(1-2), 236-249. Vernant, P., F. Hivert, J. Chéry, P. Steer, R. Cattin, and A. Rigo (2013), Erosion-induced isostatic rebound triggers extension in low convergent mountain ranges, geology, 41(4), 467-470.

Caregiving burden and uplifts: a contradiction or a protective partnership for the quality of life of parents and their children with asthma?

PubMed

Silva, Neuza; Carona, Carlos; Crespo, Carla; Canavarro, Maria Cristina

2015-04-01

Parental caregiving in the context of pediatric chronic conditions is a multifaceted experience that encompasses negative (burdens) and positive dimensions (uplifts), which may support risk and protective processes that influence family adaptation. This study aimed to examine the caregiving experience of parents caring for a child with asthma and the moderating role of caregiving uplifts on the associations between caregiving burden and quality of life (QoL) of parents and their children. Participants were 180 dyads of children/adolescents with asthma between 8 and 18 years of age and one of their parents. The parents reported on caregiving burden and uplifts and on their QoL, and the children/adolescents completed a self-report measure of generic QoL. Results showed that although parents of children with intermittent asthma and parents of younger children presented higher levels of caregiving burden, noncontrolled asthma was the only clinical variable representing a significant risk factor for decreased QoL in children. Significant negative and positive associations were found between burden dimensions and QoL and between caregiving uplifts and QoL, respectively, in parents and children. Additionally, caregiving uplifts moderated the negative link between relationship burden and parents' QoL. These results suggest that, far from being contradictory, caregiving uplifts may co-occur with high levels of burden and may constitute a protective factor against the deleterious effect of the caregiving burden on parents' QoL and a resource that directly contributes to children's QoL. This risk-resistance approach to family caregiving may contribute to operationalizing strength-based interventions in the context of pediatric asthma. (c) 2015 APA, all rights reserved).

Architecture and morphology of coral reef sequences. Modeling and observations from uplifting islands of SE Sulawesi, Indonesia

NASA Astrophysics Data System (ADS)

Pastier, Anne-Morwenn; Husson, Laurent; Bezos, Antoine; Pedoja, Kevin; Elliot, Mary; Hafidz, Abdul; Imran, Muhammad; Lacroix, Pascal; Robert, Xavier

2016-04-01

During the Late Neogene, sea level oscillations have profoundly shaped the morphology of the coastlines of intertropical zones, wherein relative sea level simultaneously controlled reef expansion and erosion of earlier reef bodies. In uplifted domains like SE Sulawesi, the sequences of fossil reefs display a variety of fossil morphologies. Similarly, the morphologies of the modern reefs are highly variable, including cliff notches, narrow fringing reefs, wide flat terraces, and barriers reefs. In this region, where uplift rates vary rapidly laterally, the entire set of morphologies is displayed within short distances. We developed a numerical model that predicts the architecture of fossil reefs sequences and apply it to observations from SE Sulawesi, accounting -amongst other parameters- for reef growth, coastal erosion, and uplift rates. The observations that we use to calibrate our models are mostly the morphology of both the onshore (dGPS and high-resolution Pleiades DEM) and offshore (sonar) coast, as well as U-Th radiometrically dated coral samples. Our method allows unravelling the spatial and temporal evolution of large domains on map view. Our analysis indicates that the architecture and morphology of uplifting coastlines is almost systematically polyphased (as attested by samples of different ages within a unique terrace), which assigns a primordial role to erosion, comparable to reef growth. Our models also reproduce the variety of modern morphologies, which are chiefly dictated by the uplift rates of the pre-existing morphology of the substratum, itself responding to the joint effects of reef building and subsequent erosion. In turn, we find that fossil and modern morphologies can be returned to uplift rates rather precisely, as the parametric window of each specific morphology is often narrow.

Role of erosion and isostasy in the Cordillera Blanca uplift: insights from Low-T thermochronology and landscape evolution modeling (northern Peru, Andes)

NASA Astrophysics Data System (ADS)

Margirier, A.; Robert, X.; Braun, J.; Laurence, A.

2017-12-01

The uplift and exhumation of the highest Peruvian peaks seems closely linked to the Cordillera Blanca normal fault that delimits and shape the western flank of the Cordillera Blanca. Two models have been previously proposed to explain the occurrence of extension and the presence of this active normal fault in a compression setting but the Cordillera Blanca normal fault and the uplift and exhumation of the Cordillera Blanca remain enigmatic. Recent studies suggested an increase of exhumation rates during the Quaternary in the Cordillera Blanca and related this increase to a change in climate and erosion process (glacial erosion vs. fluvial erosion). The Cordillera Blanca granite has been significantly eroded since its emplacement (12-5 Ma) indicating a significant mass of rocks removal. Whereas it has been demonstrated recently that the effect of eroding denser rocks can contribute to an increase of uplift rate, the impact of erosion and isostasy on the increase of the Cordillera Blanca uplift rates has never been explored. Based on numerical modeling of landscape evolution we address the role of erosion and isostasy in the uplift and exhumation of the Cordillera Blanca. We performed inversions of the present-day topography, total exhumation and thermochronological data using a landscape evolution model (FastScape). Our results evidence the contribution of erosion and associated flexural rebound to the uplift of the Cordillera Blanca. Our models suggest that the erosion of the Cordillera Blanca dense intrusion since 3 Ma could also explain the Quaternary exhumation rate increase in this area. Finally, our results allow to question the previous models proposed for the formation of the Cordillera Blanca normal fault.

Uplift of symmetrical anchor plates by using grid-fixed reinforced reinforcement in cohesionless soil

NASA Astrophysics Data System (ADS)

Niroumand, Hamed; Kassim, Khairul Anuar

2014-03-01

Uplift response of symmetrical anchor plates with and without grid fixed reinforced (GFR) reinforcement was evaluated in model tests and numerical simulations by Plaxis. Many variations of reinforcement layers were used to reinforce the sandy soil over symmetrical anchor plates. In the current research, different factors such as relative density of sand, embedment ratios, and various GFR parameters including size, number of layers, and the proximity of the layer to the symmetrical anchor plate were investigated in a scale model. The failure mechanism and the associated rupture surface were observed and evaluated. GFR, a tied up system made of fiber reinforcement polymer (FRP) strips and end balls, was connected to the geosynthetic material and anchored into the soil. Test results showed that using GFR reinforcement significantly improved the uplift capacity of anchor plates. It was found that the inclusion of one layer of GFR, which rested directly on the top of the anchor plate, was more effective in enhancing the anchor capacity itself than other methods. It was found that by including GFR the uplift response was improved by 29%. Multi layers of GFR proved more effective in enhancing the uplift capacity than a single GFR reinforcement. This is due to the additional anchorage provided by the GFR at each level of reinforcement. In general, the results show that the uplift capacity of symmetrical anchor plates in loose and dense sand can be significantly increased by the inclusion of GFR. It was also observed that the inclusion of GFR reduced the requirement for a large L/D ratio to achieve the required uplift capacity. The laboratory and numerical analysis results are found to be in agreement in terms of breakout factor and failure mechanism pattern.

Ancestral Rocky Mountian Tectonics: A Sedimentary Record of Ancestral Front Range and Uncompahgre Exhumation

NASA Astrophysics Data System (ADS)

Smith, T. M.; Saylor, J. E.; Lapen, T. J.

2015-12-01

The Ancestral Rocky Mountains (ARM) encompass multiple crustal provinces with characteristic crystallization ages across the central and western US. Two driving mechanisms have been proposed to explain ARM deformation. (1) Ouachita-Marathon collision SE of the ARM uplifts has been linked to an E-to-W sequence of uplift and is consistent with proposed disruption of a larger Paradox-Central Colorado Trough Basin by exhumation of the Uncompahgre Uplift. Initial exhumation of the Amarillo-Wichita Uplift to the east would provide a unique ~530 Ma signal absent from source areas to the SW, and result in initial exhumation of the Ancestral Front Range. (2) Alternatively, deformation due to flat slab subduction along a hypothesized plate boundary to the SW suggests a SW-to-NE younging of exhumation. This hypothesis suggests a SW-derived Grenville signature, and would trigger uplift of the Uncompahgre first. We analyzed depositional environments, sediment dispersal patterns, and sediment and basement zircon U-Pb and (U-Th)/He ages in 3 locations in the Paradox Basin and Central Colorado Trough (CCT). The Paradox Basin exhibits an up-section transition in fluvial style that suggests a decrease in overbank stability and increased lateral migration. Similarly, the CCT records a long-term progradation of depositional environments from marginal marine to fluvial, indicating that sediment supply in both basins outpaced accommodation. Preliminary provenance results indicate little to no input from the Amarillo-Wichita uplift in either basin despite uniformly westward sediment dispersal systems in both basins. Results also show that the Uncompahgre Uplift was the source for sediment throughout Paradox Basin deposition. These observations are inconsistent with the predictions of scenario 1 above. Rather, they suggest either a synchronous response to tectonic stress across the ARM provinces or an SW-to-NE pattern of deformation.

Crustal Uplift in the Southcentral Alaska Subduction Zones: A New Analysis and Interpretation of Tide Gauge Observations

NASA Technical Reports Server (NTRS)

Cohen, Steven C.; Freymueller, Jeffrey T.

1999-01-01

We have examined the sea level height tide records at seven tide gauge sites in the region of southcentral Alaska that were affected by the 1964 Prince William Sound earthquake to determine the history of crustal uplift subsequent to the earthquake. There is considerable variation in the behavior depending on the location of the site relative to the 1964 rupture. At Seward, on the eastern side of the Kenai Peninsula we find a slow uplift that is consistent with elastic strain accumulation while at Seldovia and Nikiski on the western side of the Kenai we find a persistent rapid uplift of about 1 cm/yr that most likely represents a long term transient response to the earthquake, but which cannot be sustained over the expected recurrence interval for a great earthquake of several hundred years. Further to the southwest, at Kodiak, we find evidence that the rate of uplift, which is still several mm/yr, has slowed significantly over the past three and a half decades. To the east of the Kenai Peninsula we find subsidence at Cordova and an uncertain behavior at Valdez. At both of these sites there is a mathematically significant time-dependence to the uplift behavior, but the data confirming this time dependence are not as convincing as at Kodiak. At Anchorage, to the north there is little evidence of vertical motion since the earthquake. We compare these long term tide gauge records to recent GPS observations. In general there is reasonable consistency except at Anchorage and Cordova where the GPS measurement indicate somewhat more rapid uplift and subsidence, respectively.

Late Quaternary Uplift Rates and Geomorphology of the Santa Fe Springs and West Coyote Folds, Los Angeles Basin, California

NASA Astrophysics Data System (ADS)

Sundermann, S. T.; Mueller, K. J.

2001-12-01

We mapped Quaternary aquifers with water wells and 5 m DEM's from IFSAR to define rates of folding along the Puente Hills blind thrust system. A cross section across Santa Fe Springs along Carfax Ave suggests 100 and 165 m of uplift of the 330 ka Gage and 650 ka Lynwood aquifers, yielding uplift rates of 0.2 mm/yr between 330-650 ka and 0.27 mm/yr beween 0-330 ka. For a 27° thrust, this yields a slip rate of 0.44 - 0.59 mm/yr. Surface folding is discernable across the Santa Fe Springs segment in the DEM, to a point 4 km west of the San Gabriel River. Aquifers correlated with reflectors in a USGS seismic profile along Carfax suggests lower relief for the Lynwood (85 m) and the Gage (59 m). We suggest the 1 km-long USGS profile images only part of the fold limb and that additional structural relief is accommodated further north, as defined by our subsurface mapping. Correlation of a shallow reflector in the seismic profile with the 15-20 ka Gaspur aquifer suggests Holocene uplift of 1.0 mm/yr. A similar analysis undertaken for the Coyote fold near Trojan Ave. suggests 85 and 229 m of uplift for the Gage and Lynwood, yielding uplift rates of 0.26 mm/yr between 0-330 ka and 0.45 mm/yr between 330-650 ka. Correlation of the Gage with a reflector on another USGS seismic profile along Trojan suggests equivalent uplift (86 m), indicating the profile images the entire width of the Coyote forelimb at this site.

Influence of orographic precipitation on the incision within a mountain-piedmont system

NASA Astrophysics Data System (ADS)

Zavala, Valeria; Carretier, Sébastien; Bonnet, Stephane

2017-04-01

The geomorphological evolution of a mountain-piedmont system depends both on tectonics and climate, as well as on couplings between the mountain and its piedmont. Although the interactions between climate and tectonics are a fundamental point for understanding the landscape evolution, the erosion of a mountain range and the sediment deposition at the mountain front, or piedmont, have been poorly studied as a coupled system. Here we focus on the conditions driving an incision within such a system. Classically, it is thought that incision results from a change in climate or uplift rates. However, it is not clear which are the specific conditions that favor the occurrence of river incision in the piedmont. In particular, studies have shown that the presence of a piedmont can modify the incision patterns, and even drive autogenic incision, without any change in external forcings. This is a crucial issue in order to interpret natural incisions in terms of uplift or climatic modifications. Such a problem is further complicated by the modification of local precipitations and temperatures during uplift, because the progressive effect of climate change may superimpose to uplift. In this work we explore the hypothesis that a mountain-piedmont coupled system may develop incision in its piedmont as a result of enhanced orographic precipitations during surface uplift. We use a landscape evolution model, Cidre, in order to explore the response of a mountain-piemont system in which the mountain is continuously uplifted but in which precipitation rates depend on elevations. Thus precipitation amounts change during the mountain uplift. We test different peaks and amplitudes of the orographic precipitation pattern, maintaining the other conditions constant. Preliminary results show that elevation-dependent precipitations drive temporary but pronounced incisions of the main rivers within the piedmont, contrary to experiments without orographic precipitations.

Measurement of tectonic surface uplift rate in a young collisional mountain belt

USGS Publications Warehouse

Abbott, L.D.; Silver, E.A.; Anderson, R. Scott; Smith, R.; Ingle, J.C.; Kling, S.A.; Haig, D.; Small, E.; Galewsky, J.; Sliter, W.

1997-01-01

Measurement of the rate of tectonically driven surface uplift is crucial to a complete understanding of mountain building dynamics. The lack of a suitable rock record typically prevents determination of this quantity, but the unusual geology of Papua New Guinea's Finisterre mountains makes measurement of this rate possible. The tectonic surface uplift rate at the Finisterre range is 0.8-2.1 mm yr-1, approximately that expected to arise from crustal thickening.

Short-term standard litter decomposition across three different ecosystems in middle taiga zone of West Siberia

NASA Astrophysics Data System (ADS)

Filippova, Nina V.; Glagolev, Mikhail V.

2018-03-01

The method of standard litter (tea) decomposition was implemented to compare decomposition rate constants (k) between different peatland ecosystems and coniferous forests in the middle taiga zone of West Siberia (near Khanty-Mansiysk). The standard protocol of TeaComposition initiative was used to make the data usable for comparisons among different sites and zonobiomes worldwide. This article sums up the results of short-term decomposition (3 months) on the local scale. The values of decomposition rate constants differed significantly between three ecosystem types: it was higher in forest compared to bogs, and treed bogs had lower decomposition constant compared to Sphagnum lawns. In general, the decomposition rate constants were close to ones reported earlier for similar climatic conditions and habitats.

Effects of power-line construction on wetland vegetation in Massachusetts, USA

NASA Astrophysics Data System (ADS)

Nickerson, Norton H.; Dobberteen, Ross A.; Jarman, Nancy M.

1989-07-01

Utility rights-of-way corridors through wetland areas generate long-term impacts from construction activities to these valuable ecosystems. Changes to and recovery of the vegetation communities of a cattail marsh, wooded swamp, and shrub/bog wetland were documented through measurements made each growing season for two years prior, five years following, and again on the tenth year after construction of a 345-kV transmission line. While both the cattail marsh and wooded swamp recovered within a few years, measures of plant community composition in the shrub/bog wetland were still lower, compared to controls, after ten years. Long-term investigations such as the one reported here help decrease uncertainty and provide valuable information for future decision making regarding construction of power utility lines through valuable and dwindling wetland resources.

An approximate fluvial equilibrium topography for the Alps

NASA Astrophysics Data System (ADS)

Stüwe, K.; Hergarten, S.

2012-04-01

This contribution addresses the question whether the present topography of the Alps can be approximated by a fluvial equilibrium topography and whether this can be used to determine uplift rates. Based on a statistical analysis of the present topography we use a stream-power approach for erosion where the erosion rate is proportional to the square root of the catchment size for catchment sizes larger than 12 square kilometers and a logarithmic dependence to mimic slope processes at smaller catchment sizes. If we assume a homogeneous uplift rate over the entire region (block uplift), the best-fit fluvial equilibrium topography differs from the real topography by about 500 m RMS (root mean square) with a strong systematic deviation. Regions of low elevation are too high in the equilibrium topography, while high-mountain regions are too low. The RMS difference significantly decreases if a spatially variable uplift function is allowed. If a strong variation of the uplift rate on a scale of 5 km is allowed, the systematic deviation becomes rather small, and the RMS difference decreases to about 150 m. A significant part of the remaining deviation apparently arises from glacially-shaped valleys, while another part may result from prematurity of the relief (Hergarten, Wagner & Stüwe, EPSL 297:453, 2010). The best-fit uplift function can probably be used for forward or backward simulation of the landform evolution.

Causes of rapid uplift and exceptional topography of Gongga Shan on the eastern margin of the Tibetan Plateau

NASA Astrophysics Data System (ADS)

Cook, Kristen L.; Hovius, Niels; Wittmann, Hella; Heimsath, Arjun M.; Lee, Yuan-Hsi

2018-01-01

Erosion and tectonic uplift are widely thought to be coupled through feedbacks involving orographic precipitation, relief development, and crustal weakening. In many orogenic systems, it can be difficult to distinguish whether true feedbacks exist, or whether observed features are a consequence of tectonic forcing. To help elucidate these interactions, we examine Gongga Shan, a 7556 m peak on the eastern margin of the Tibetan Plateau where cosmogenic 10Be basin-wide erosion rates reach >5 mm/yr, defining a region of localized rapid erosion associated with a restraining bend in the left-lateral Xianshuihe Fault. Erosion rates are consistent with topography, thermochronometry, and geodetic data, suggesting a stable pattern of uplift and exhumation over at least the past 2-3 My. Transpression along the Xianshuihe Fault, orographically enhanced precipitation, thermally weakened crust, and substantial local relief all developed independently in the Gongga region and existed there prior to the uplift of Gongga Shan. However, only where all of these conditions are present do the observed topographic and erosional extremes exist, and their relative timing indicates that these conditions are not a consequence of rapid uplift. We conclude that their collocation at 3-4 Ma set into motion a series of feedbacks between erosion and uplift that has resulted in the exceptionally high topography and rapid erosion rates observed today.

Episodic yo-yo movements (epeirogeny) on continental platform intracratonic basins: Need for reinterpretation of paleogeography, faunal extinctions, and source rock maturity

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

Friedman, G.M.

1989-08-01

In the Appalachian basin and Mississippi Valley, dates for epeirogeny cluster between 250 and 300 Ma, with the completion of the uplifts at about the Permian-Triassic boundary. In the Fennoscandian shield and elsewhere, uplifts appear to be of comparable age. This was the time when the continents had collided to become supercontinent Pangea which, as a result of uplift, stood high above sea level; environments became stressful, weather patterns changed, and faunal extinctions occurred. Large-scale epeirogeny began again at about 100 Ma, with some dates at about 60 Ma marking Cretaceous-Tertiary boundary extinctions. Precambrian basements, such as the Adirondacks, themore » Canadian shield, and the Arabo-Nubian shield suffered domal uplift during the Oligocene-Miocene, especially in the Miocene to Holocene interval. Oceanic sedimentation rates were elevated in the Miocene to accommodate this increased continental erosion. Active Holocene uplift in the Arabo-Nubian shield involving several meters or even tens of meters occurred as recently as between 3,405 {plus minus} 90 years and 2,465 {plus minus} 155 years ago.« less

Ongoing drought-induced uplift in the western United States.

USGS Publications Warehouse

Borsa, Adrian Antal; Agnew, Duncan Carr; Cayan, Daniel R.

2014-01-01

The western United States has been experiencing severe drought since 2013. The solid earth response to the accompanying loss of surface and near-surface water mass should be a broad region of uplift. We use seasonally adjusted time series from continuously operating global positioning system stations to measure this uplift, which we invert to estimate mass loss. The median uplift is 5 millimeters (mm), with values up to 15 mm in California’s mountains. The associated pattern of mass loss, ranging up to 50 centimeters (cm) of water equivalent, is consistent with observed decreases in precipitation and streamflow. We estimate the total deficit to be ~240 gigatons, equivalent to a 10-cm layer of water over the entire region, or the annual mass loss from the Greenland Ice Sheet.

Initiation and development of the southern California uplift along its northern margin

USGS Publications Warehouse

Stein, R.S.; Thatcher, W.; Castle, R.O.

1979-01-01

Analysis of three first-order leveling lines that traverse the White Wolf fault (site of the 1952 M = 7.7 earthquake), each resurveyed nine times between 1926 and 1974, reveals probable preseismic tilting, major coseismic movements, and a spatial association between these movements and the subsequently recognized southern California uplift. In examining the vertical control record, we have both searched for evidence of systematic errors and excluded from consideration portions of the lines contaminated by subsurface fluid and gas extraction. Movements have been referred to an invariant datum based on the 1926 position of tidal BM 8 in San Pedro, corrected for subsequent eustatic sea-level change. An 8 ??rad up-to-the-north preseismic tilt (6 cm/7.5 km) was apparently recorded on two adjacent line segments within 10 km of the 1952 epicenter between 1942 and 1947. It is possible, however, that this tilt was in part caused by extraction-induced subsidence at one of the six releveled benchmarks. Data also show evidence of episodic tilts that are not earthquake related. At the junction of the Garlock and San Andreas faults, for example, an ???5 ??rad up-to-the-north tilt (7.2 cm/???16 km) took place between Lebec and Grapevine within three months during 1964. Comparison of the 1947 and 1953 surveys, which includes the coseismic interval, shows that the SW-fault end (nearest the epicenter) and the central fault reach sustained four times the uplift recorded at the NE end of the fault (+72 cm SW, +53 cm Central, +16 cm NE). A regional postseismic uplift of 4 cm extended ???25 km to either side of the fault after the main event, from 1953 to 1956. An interval of relative quiescence followed at least through 1959, in which the elevation change did not exceed ??3 cm. The detailed pattern of aseismic uplift demonstrates that movement proceeded in space-time pulses: one half of the uplift at the SW-fault end and extending southward occurred between 1959 and 1961, one half of the uplift at the NE-fault end and extending eastward occurred between 1961 and 1965, while the central fault reach sustained successive pulses of subsidence, uplift, and collapse (-4 cm, 1953-1960; +7 cm, 1960-1965; -2 cm, 1965-1970). In addition, the number of aftershocks concentrated near the fault ends increased in the NE relative to the SW from 1952 to 1974. These observations suggest that the aseismic uplift may have migrated northeastward from 1959 to 1965 at an approximate rate of 7-16 km/yr. Evidence for a mechanical coupling between the earthquake and the subsequent aseismic uplift is equivocal. At both fault ends, the major NWbounding flexure or tilted front of the southern California uplift is spatially coincident with the coseismic flexure that preceded it. In addition, the postulated migration of vertical deformation is similar to the 1952 seismic event in which the rupture initiated at the SW end of the fault and then propagated to the NE-fault end. However, the spatial distribution of aseismic uplift, nearly identical at both fault ends and to the south and east, and near zero in the central fault reach, is distinctly different from the nonuniform and localized coseismic deformation. ?? 1979.

Quaternary Tectonic and Climatic Processes shaping the Central Andean hyperarid forearc (southern Peru)

NASA Astrophysics Data System (ADS)

Audin, Laurence; Benavente, Carlos; Zerathe, Swann; Saillard, Marianne; Hall, Sarah R.; Farber, Daniel L.

2015-04-01

Understanding the forearc structure and processes related to Quaternary evolution and uplift of the Western Andean Cordillera remains an outstanding scientific issue. Models of Andean Plateau evolution based on Tertiary volcanic stratigraphy since 5Ma suggest that the deformation was focused along the eastern margin of the plateau and that minimal uplift occurred along the Pacific margin. On the contrary, new tectonic data and Quaternary surface 10Be dating highlight the presence of recently active deformation, incision and alluvial processes within the upper Andean forearc together with a regional uplift of the coastal zone. Additionally, the high obliquity observed in the northern Arica Bend region makes it an ideal target to discuss whether partitioning of the oblique convergence is accommodated by the neotectonic features that dissect the Quaternary forearc. Our goals are both to decipher the Quaternary tectonic and climatic processes shaping the hyperarid forearc along strike and across strike. Finally, we aim to quantify the respective influence of these factors in the overall uplift of the Western Andes. Indeed, sequences of pediment surfaces, landslide products, paleolake deposits and marine terraces found along the oblique Peruvian margin are a unique set of datable markers that can be used to quantify the rates of Quaternary processes. In this study, we focus on the southern Peru hyperarid Atacama area where regional surfaces and tectonic markers (scarps, folds, temporary streams and paleolake levels offsets…) are well preserved for the Quaternary timescale. Numerous landsliding events align on the major fault segments and reflect Plio-Pleistocene climatic and tectonic activity together with filled and strath terraces. As the present day sea-level is one of the highest levels recorded for Quaternary time span, any emerged marine terrace is preserved by tectonic coastal uplift. In particular, the geomorphic and chronologic correlation between marine and continental planation surfaces or terraces permit to deduce net vertical rates and suggests that the along strike uplift affected not only the coast but also the overall ~50 km-wide forearc of the Western Andes. We produced a chronology of remnant low-relief surfaces and a new neotectonic map of the Central Andean forearc between ~14° and 18°S based on detailed field mapping and 10Be cosmogenic dating. We address 1) the spatial and temporal correlations of various markers, and 2) the correlation of the surface abandonment ages to various regional climatic events and 3) the description of neotectonic activity accommodating both uplift and partitioning. Multiple markers yield 10Be surface abandonment ages that spanning 35 ka to >2 Ma. Erosion surfaces >2 Ma yield low erosion rates of <0.1mm/yr. However uplift rates of ~0.1-1mm/yr and multiple surfaces dated at ~35 ka suggest that the hyperarid forearc landscape has been recently modified through Quaternary surface uplift and climatic events, contradicting the Miocene fossil forearc hypothesis. Generally, surface abandonment ages and activated landslides periods tend to correlate with cold wet periods preceding Plio Pleistocene deglaciation on the Altiplano. Finally, neotectonic oblique faults connecting at depth participate to topography building in the Arica Bend region and suggest that Quaternary surface abandonment is the result of both surface uplift in the forearc and specific high-discharge climate periods in the high Andes. Obtained Quaternary regional uplift rates and individual slip-rates suggest that the Andean forearc may accommodate as much as 0.5 to 1 mm/yr of regional uplift for the Quaternary time period.

Preliminary stable isotope results from the Mohos peat bog, East-Carpathians

NASA Astrophysics Data System (ADS)

Túri, Marianna; Palcsu, László; Futó, István; Hubay, Katalin; Molnár, Mihály; Rinyu, László; Braun, Mihály

2016-04-01

This work provides preliminary results of an isotope investigation carried out on a peat core drilled in the ombrotrophic Mohos peat bog, Ciomadul Mountain, (46°8'3.60"N, 25°54'19.43"E, 1050 m.a.s.l.), East Carpathians, Romania. The Ciomadul is a single dacitic volcano with two craters: the younger Saint Ana and the older Mohos which is a peat bog, and surrounded by a number of individual lava domes as well as a narrow volcaniclastic ring plain volcano. A 10 m long peat core has been taken previously, and is available for stable oxygen and carbon isotope analysis. It is known from our previous work (Hubay et al., 2015) that it covers a period from 11.500 cal year B.P. to present. The peat bog is composed mainly of Sphagnum, which has a direct relationship with the environment, making it suitable for examine the changes in the surrounding circumstances. Isotopic analysis of the prepared cellulose from Sphagnum moss has the attribute to provide such high resolution quantitative estimates of the past climate and there is no such climate studies in this area where the past climate investigations based on oxygen isotope analysis of the Sphagnum. Oxygen and carbon stable isotope analysis were carried out on the hemicellulose samples, which were chemically prepared for 14C dating and taken from every 30 cm of the 10 m long peat core. The oxygen isotope composition of the precipitation can be revealed from the δ18O values of the prepared cellulose samples, since, while carbon isotope ratio tells more about the wet and dry periods of the past. Studying both oxygen and carbon isotope signatures, slight fluctuations can be seen during the Holocene like some of the six periods of significant climate changes can be seen in this resolution during the time periods of 9000-8000, 6000-5000, 4200-3800, 3500-2500, 1200-1000, and 600-150 cal yr B.P. Additionally, the late Pleistocene - early Holocene environmental changes can be clearly observed as Pleistocene peat samples have increasingly negative delta values as going back in time. All measurements were carried out in Hertelendi Laboratory of Environmental Studies, Institute for Nuclear Research, Hungarian Academy of Sciences. Katalin Hubay, Mihály Braun, Sándor Harangi, László Palcsu, Marianna Túri, László Rinyu, Mihály Molnár, 2015. European Geosciences Union (EGU) General Assembly 2015, Radiocarbon dating of Sphagnum cellulose from Mohos peat bog, East Carpathians, accepted in CL5.10/GM1.10 Geophysical Research Abstracts Vol. 17, EGU2015-10813, 2015

THE BOG TURTLE: Georgia's Rarest Turtle.

ERIC Educational Resources Information Center

Wilson, Lawrence

1991-01-01

This article discusses the description and range, the status, the habitat, the natural history, and the proper management of the diminutive, rare, and endangered species known as the box turtle. (JJK)

Effects of Caledonian tectonism in Arctic Canada

NASA Astrophysics Data System (ADS)

Miall, Andrew D.

1986-11-01

Several north-trending structures in the Canadian Arctic islands are interpreted as Caledonian in origin, in the sense that they probably represent intraplate tectonism triggered by the closing of the Iapetus Ocean along the Greenland-Scandinavia-Svalbard Caledonian suture. These structures include the Boothia uplift, Rens Fiord uplift, Inglefield uplift (redefined unit, replacing Bache Peninsula arch), and possibly several other structures, such as the Cornwall arch, which are now expressed mainly in Mesozoic-Cenozoic strata but may represent rejuvenated Caledonian lineaments.

Evidence for Holocenic uplift at Somma-Vesuvius

NASA Astrophysics Data System (ADS)

Marturano, Aldo; Aiello, Giuseppe; Barra, Diana; Fedele, Lorenzo; Grifa, Celestino; Morra, Vincenzo; Berg, Ria; Varone, Antonio

2009-07-01

Detailed stratigraphical, archaeological, micropalaeontological, archaeometrical and petrochemical analyses of samples from trenches and boreholes at insula of Casti Amanti, in Pompeii, allowed a faithful reconstruction of the recent environmental evolution of the site. The present data clearly indicate the alternation of both subaerial and shallow marine conditions during Holocene times. Taking into account the relative local sea level variations, a ~ 30 m ground uplift event in the last 6 kyr (with an average vertical uplift rate of ~ 5 mm/yr) was inferred for the first time.

Quarternary Pollen Analysis in Secondary School Ecology

ERIC Educational Resources Information Center

Slater, F. M.

1972-01-01

Describes techniques for studying historic changes in climate by analysis of pollen preserved in peat bogs. Illustrates the methodology and data analysis techniques by reference to results from English research. (AL)

Seismic Reflection Characteristic and Structure Unit Division of Nanwei Uplift in the Nansha Waters, South China Sea

NASA Astrophysics Data System (ADS)

Guo, L.; Zhan, W.; Yao, Y.

2016-12-01

Nanwei uplift is located in the continent-ocean transition zone at the southern margin of the South China Sea (SCS). It has the structural characteristics in typical passive margin models. Attributed to squeezing action, the anticline and faulted anticline structure were well developed since Oligocene. The development of organic reef and marine mudstone deposit indicated the drifting and subsidence stage. In this area, the structural evolution is not only related to the dynamic systems of rifting, basin spreading and expansion ending, but also to the collisions between different plates. Meanwhile, a large number of continental margin rifting basins with rich oil and gas resources developed in Nanwei uplift. It is meaningful to analyze the characteristics of seismic reflection waves. Also, two main structural unit were divided for studying the special structures and stratigraphic features in this paper. Two high-resolution single-channel seismic Line Nan-1 and Line Nan-2 in the Nansha Waters, acquired by the trial vessel "Shiyan 2" of the South China Sea Institute of Oceanology in 2013, is interpreted and analyzed in this study. The profiles show that there are a lot of normal fault half-garben systems and depressions in NE direction. Five seismic interfaces have been distinguished, named T0,T3,T4,T5 and Tg respectively. It corresponds to different regional unconformities in different geological age which indicated the characteristics of regional tectonics. On the basis of tectonic shape and previous geophysical data, it is believed that the Nanwei uplift zone is mainly composed of two structural units, the southern subsidence belt and northern buried volcanic uplift belt. The general range of zoning is also discussed in this paper. It is considered that the buried volcanic uplift belt mainly involved the marginal area along the southern ocean basin from 63-72 km wide in SE direction, the neighboring subsidence belt in rifting stage is parallel to the buried volcanic uplift belt with 57.5-128 km wide. In addition, the epicenter distributions of sporadic and larger than 4 magnitude earthquakes suggest that the entire Nanwei uplift is still a relatively stable tectonic activity zone, the crustal stability is good.

InSAR detection of aquifer recovery: Case studies of Koehn Lake (central California) and Lone Tree Gold Mine (Basin and Range)

NASA Astrophysics Data System (ADS)

Wdowinski, S.; Greene, F.; Amelung, F.

2013-12-01

Anthropogenic intervention in groundwater flow and aquifer storage often results in vertical movements of Earth's surface, which are well detected by InSAR observations. Most anthropogenic intervention occurs due to groundwater extraction for both agriculture and human consumption and results in land subsidence. However in some cases, ending anthropogenic intervention can lead to aquifer recovery and, consequently, surface uplift. In this study we present two such cases of aquifer recovery. The first case is the aquifer beneath Koehn Lake in Central California, which was overused to meet agricultural demands until the 1990's. The second case is the Lone Tree Gold Mine in Nevada that during active mining in the 1991-2006 groundwater pumping disrupted the aquifer and cause subsidence. But after mining ceased, groundwater flow was recovered and resulted in uplift. In both cases we studied the surface uplift using InSAR time series observations. We conduct an ERS and Envisat InSAR survey over Koehn Lake in California and Lone Tree Gold Mine in Nevada between 1992 and 2010. We followed the SBAS algorithm to generate a time-series of ground displacements and average velocities of pixels, which remain coherent through time in the SAR dataset. A total of 100 and 80 combined ERS and Envisat SAR dates are inverted for Koehn Lake and Lone Tree Gold Mine respectively. Results for the Koehn Lake area indicate a rapid uplift of about 3.5 mm/yr between 1992-2000 and a slower uplift rate of 1.6 mm/yr between 2000-2004, suggesting a decrease in the recovery process. The observed uplift correlates well with groundwater level increase in the Koehn Lake area. Results for the Lone Tree Gold Mine show a constant subsidence (~ 1 cm/yr) due to groundwater extraction between 1992-2006, but uplift of ~1 cm/yr since the beginning of 2007. In both case studies, InSAR observations reveal that the aquifer recovery is accompanied by surface uplift. We plan to use the InSAR observations and the groundwater level records to model and better understand aquifer recovery processes.

Vertical Stratification of Peat Pore Water Dissolved Organic Matter Composition in a Peat Bog in Northern Minnesota: Pore Water DOM composition in a peat bog

DOE PAGES

Tfaily, Malak M.; Wilson, Rachel M.; Cooper, William T.; ...

2018-01-29

Here, we characterized dissolved organic matter (DOM) composition throughout the peat column at the Marcell S1 forested bog in northern Minnesota and tested the hypothesis that redox oscillations associated with cycles of wetting and drying at the surface of the fluctuating water table correlate with increased carbon, sulfur, and nitrogen turn over. We found significant vertical stratification of DOM molecular composition and excitation-emission matrix parallel factor analysis components within the peat column. In particular, the intermediate depth zone (~ 50 cm) was identified as a zone where maximum decomposition and turnover is taking place. Surface DOM was dominated by inputsmore » from surface vegetation. The intermediate depth zone was an area of high organic matter reactivity and increased microbial activity with diagenetic formation of many unique compounds, among them polycyclic aromatic compounds that contain both nitrogen and sulfur heteroatoms. These compounds have been previously observed in coal-derived compounds and were assumed to be responsible for coal's biological activity. Biological processes triggered by redox oscillations taking place at the intermediate depth zone of the peat profile at the S1 bog are assumed to be responsible for the formation of these heteroatomic PACs in this system. Alternatively, these compounds could stem from black carbon and nitrogen derived from fires that have occurred at the site in the past. Surface and deep DOM exhibited more similar characteristics, compared to the intermediate depth zone, with the deep layer exhibiting greater input of microbially degraded organic matter than the surface suggesting that the entire peat profile consists of similar parent material at different degrees of decomposition and that lateral and vertical advection of pore water from the surface to the deeper horizons is responsible for such similarities. Lastly, our findings suggest that molecular composition of DOM in peatland pore water is dynamic and is a function of ecosystem activity, water table, redox oscillation, and pore water advection.« less

Vertical Stratification of Peat Pore Water Dissolved Organic Matter Composition in a Peat Bog in Northern Minnesota: Pore Water DOM composition in a peat bog

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

Tfaily, Malak M.; Wilson, Rachel M.; Cooper, William T.

Here, we characterized dissolved organic matter (DOM) composition throughout the peat column at the Marcell S1 forested bog in northern Minnesota and tested the hypothesis that redox oscillations associated with cycles of wetting and drying at the surface of the fluctuating water table correlate with increased carbon, sulfur, and nitrogen turn over. We found significant vertical stratification of DOM molecular composition and excitation-emission matrix parallel factor analysis components within the peat column. In particular, the intermediate depth zone (~ 50 cm) was identified as a zone where maximum decomposition and turnover is taking place. Surface DOM was dominated by inputsmore » from surface vegetation. The intermediate depth zone was an area of high organic matter reactivity and increased microbial activity with diagenetic formation of many unique compounds, among them polycyclic aromatic compounds that contain both nitrogen and sulfur heteroatoms. These compounds have been previously observed in coal-derived compounds and were assumed to be responsible for coal's biological activity. Biological processes triggered by redox oscillations taking place at the intermediate depth zone of the peat profile at the S1 bog are assumed to be responsible for the formation of these heteroatomic PACs in this system. Alternatively, these compounds could stem from black carbon and nitrogen derived from fires that have occurred at the site in the past. Surface and deep DOM exhibited more similar characteristics, compared to the intermediate depth zone, with the deep layer exhibiting greater input of microbially degraded organic matter than the surface suggesting that the entire peat profile consists of similar parent material at different degrees of decomposition and that lateral and vertical advection of pore water from the surface to the deeper horizons is responsible for such similarities. Lastly, our findings suggest that molecular composition of DOM in peatland pore water is dynamic and is a function of ecosystem activity, water table, redox oscillation, and pore water advection.« less

Dissolved organic matter degradation by sunlight coagulates organo-mineral colloids and produces low-molecular weight fraction of metals in boreal humic waters

NASA Astrophysics Data System (ADS)

Oleinikova, Olga V.; Drozdova, Olga Yu.; Lapitskiy, Sergey A.; Demin, Vladimir V.; Bychkov, Andrey Yu.; Pokrovsky, Oleg S.

2017-08-01

Photochemical degradation of dissolved organic matter (DOM) is recognized as the major driver of CO2 emission to the atmosphere from the inland waters of high latitudes. In contrast to numerous studies of photo-induced DOM transformation, the behavior of trace element (TE) during photodegradation of boreal DOM remains virtually unknown. Towards a better understanding of concentration, size fractionation and speciation change of DOM and TE in boreal waters subjected to solar radiation, we conducted on-site photo-degradation experiments in stream and bog water collected from a pristine zone of the Northern Karelia (Russian subarctic). The removal of Fe and Al occurred only in the bog water (90% and 50% respectively, over 5 days of reaction), whereas no detectable decrease of dissolved (<0.22 μm) Al and Fe concentration was observed in the boreal stream. A number of low-soluble TE linked to Fe-rich organo-mineral colloids followed the behavior of Fe during bog water exposure to sunlight: Al, P, Ti, V, Cr, As, Y, Zr, REEs, Hf, Th, Pb and U. The second group of elements (Li, B, Mg, Ca, Sr, Ba, Na, K, Rb, Si, Mn, Ni, Cu, Co, Cd, Sb) was indifferent to photodegradation of DOM and exhibited a non-systematic variation (±10-15% from the control) of <0.22 μm fraction in the course of sunlight exposure. The bog water insolation yielded a factor of 3 ± 1 increase of low molecular weight (LMW < 1 kDa) fraction of organic carbon, Al, Fe, U, Mg, Ca, Mn, Co, Ni, Sr, Cd and Ba after 200 h of sunlight exposure compared to the dark control. The LMW< 1 kDa fraction was preferentially enriched in Fe, Al, Ca, Mg and other divalent metals relative to Corg. The climate warming leading to water temperature rise in the boreal zone will intensify the Fe and Al hydroxide coagulation while increasing the production of LMW organic ligands and free metals and metal - organic complexes.

Variations in the long-term uplift rate due to the Altiplano-Puna magma body observed with Sentinel-1 interferometry

NASA Astrophysics Data System (ADS)

Lau, Nicholas; Tymofyeyeva, Ekaterina; Fialko, Yuri

2018-06-01

We present new Interferometric Synthetic Aperture Radar (InSAR) observations of surface deformation in the Altiplano-Puna region (South America) where previous studies documented a broad uplift at an average rate of ∼10 mm/yr. We use data from the Sentinel-1 satellite mission to produce high-resolution velocity maps and time series of surface displacements between years 2014-2017. The data reveal that the uplift has slowed down substantially compared to the 1992-2010 epoch and is characterized by short-term fluctuations on time scales of months to years. The observed variations in uplift rate may indicate a non-steady supply of melt and/or volatiles from the partially molten Altiplano-Puna Magma Body (APMB) into an incipient diapir forming in the roof of the APMB.

Wilcox group (Paleocene to Eocene) coals of the Sabine Uplift area, Texas and Louisiana

USGS Publications Warehouse

Hook, Robert W.; Warwick, Peter D.; SanFilipo, John R.; Warwick, Peter D.; Karlsen, Alexander K.; Merrill, Matthew D.; Valentine, Brett J.

2011-01-01

The Wilcox Group (Paleocene to Eocene) of the Sabine uplift, a structural arch in northeastern Texas and northwestern Louisiana (Figure 1), has lignite zones that approach subbituminous rank (see Chapter 4, this publication). These coals are among the highest quality resources known within the Gulf Coastal Plain because of their low ash yield and sulfur content. The surface expression of the Sabine uplift is defined by the contact between coal-bearing rocks of the Wilcox Group and overlying fluvial rocks of the Carrizo Sand, which is the basal unit of the Claiborne Group (Figures 2, 3). The Sabine uplift study area includes parts of Harrison, Marion, Nacogdoches, Panola, Rusk, Sabine, San Augustine, and Shelby Counties in Texas and Bossier, Caddo, De Soto, Natchitoches, Red River, and Sabine Parishes in Louisiana (Figure 1). Adjacent counties and parishes that include the subsurface Wilcox Group extend the regional Sabine uplift area. The Wilcox in the subsurface is underlain by the Midway Group (Figure 3), a mudstone-dominated marine sequence of Paleocene age. Quaternary alluvium and terrace deposits overlying the Wilcox Group at the surface are limited to areas of modern drainage.The total thickness of the Wilcox Group within the Sabine uplift area ranges from approximately 400 ft on outcrop to 2500 ft in subsurface (Kaiser, 1990). In a few places, the contact between the overlying Carrizo Sand and Wilcox Group is erosional, but in other places, the contact is gradational.

New insights on multiple seismic uplift on the Main Frontal Thrust near the Ratu river, Eastern Nepal using high-resolution topography

NASA Astrophysics Data System (ADS)

Karakas, Cagil; Tapponnier, Paul; Nath Sapkota, Soma; Coudurier Curveur, Aurelie; Ildefonso, Sorvigenaleon; Gao, Mingxing; Bollinger, Laurent; Klinger, Yann

2016-04-01

The number of localities along the Main Frontal Thrust, between 85°49' to 86°27' E, where new data corroborates the surface emergence of the great M ≈ 8.4, 1934 Bihar-Nepal and 1255 AD earthquakes has increased over the past years. Here we show new high-resolution, quantitative evidences of surface rupture and co-seismic uplift near the Ratu river area. We present a refined map of uplifted terrace surfaces and abandoned paleo-channels truncated by the MFT, obtained by the combination of newly acquired high resolution Digital Elevation Models from Total station, Terrestrial Lidar Scanner (TLS), Unmanned Aerial Vehicle (UAV) and kinematic GPS surveys. In the Ratu valley, using these new high-resolution topographic datasets, we identify six and possibly seven distinct terrace levels uplifted parallel to the riverbed, lying unconformably on top of folded Siwaliks. Several sets of measurements may be taken to imply broadly characteristic increments of throw during sequences of at least six to seven events of riverbed abandonment related to co-seismic uplifts. Newly collected detrital charcoals from several pits and from a rejuvenated paleoseismological wall will help assess more precisely uplift and shortening rates over the length of segments of the MFT east and west of Bardibas. A regional comparison of comparable long-term paleoseismological data at other sites along the 1934 rupture length is in progress.

A case of rapid rock riverbed incision in a coseismic uplift reach and its implications

NASA Astrophysics Data System (ADS)

Huang, Ming-Wan; Pan, Yii-Wen; Liao, Jyh-Jong

2013-02-01

During the 1999 Chi-Chi earthquake (Mw = 7.6) in Taiwan, the coseismic displacement induced fault scarps and a pop-up structure in the Taan River. The fault scarps across the river experienced maximum vertical slip of 10 m, which disturbed the dynamic equilibrium of the fluvial system. As a result, rapid incision in the weak bedrock, with a maximum depth of 20 m, was activated within a decade after its armor layer was removed. This case provides an excellent opportunity for closely tracking and recording the progressive evolution of river morphology that is subjected to coseismic uplift. Based on multistaged orthophotographs and digital elevation model (DEM) data, the process of morphology evolution in the uplift reach was divided into four consecutive stages. Plucking is the dominant mechanism of bedrock erosion associated with channel incision and knickpoint migration. The astonishingly high rate of knickpoint retreat (KPR), as rapid as a few hundred meters per year, may be responsible for the rapid incision in the main channel. The reasons for the high rate of KPR are discussed in depth. The total length of the river affected by the coseismic uplift is 5 km: 1 km in the uplift reach and 4 km in the downstream reach. The downstream reach was affected by a reduction in sediment supply and increase in stream power. The KPR cut through the uplift reach within roughly a decade; further significant flooding in the future will mainly cause widening instead of deepening of the channel.

New insights on timing of oil and gas generation in the central Gulf Coast interior zone based on hydrous-pyrolysis kinetic parameters

USGS Publications Warehouse

Lewan, Michael D.; Dutton, Shirley P.; Ruppel, Stephen C.; Hentz, Tucker F.

2002-01-01

Timing of oil and gas generation from Turonian and Smackover source rocks in the central Gulf CoastInterior Zone was determined in one-dimensional burial-history curves (BHCs) using hydrous-pyrolysis kinetic parameters. The results predict that basal Smackover source-rock intervals with Type-IIS kerogen completed oil generation between 121 and 99 Ma, and Turonian source-rocks with Type-II kerogen remain immature over most of the same area. The only exception to the latter occurs in the northwestern part of the Mississippi salt basin, where initial stages of oil generation have started as a result of higher thermal gradients. This maturity difference between Turonian and Smackover source rocks is predicted with present-day thermal gradients. Predicted oil generation prior to the Sabine and Monroe uplifts suggests that a significant amount of the oil emplaced in Cretaceous reservoirs of these uplifts would have been lost during periods of erosion. Hydrous-pyrolysis kineticparameters predict that cracking of Smackover oil to gas started 52 Ma, which postdates major uplift and erosional events of the Sabine and Monroe uplifts. This generated gas would accumulate and persist in these uplift areas as currently observed. The predicted timing of oil and gas generation with hydrous-pyrolysis kinetic parameters is in accordance with the observed scarcity of oil from Turonian source rocks, predominance of gas accumulations on the Sabine and Monroe uplifts, and predominance of oil accumulations along the northern rim of the Interior Zone.

Tectonic uplift, threshold hillslopes, and denudation rates in a developing mountain range

USGS Publications Warehouse

Binnie, S.A.; Phillips, W.M.; Summerfield, M.A.; Fifield, L.K.

2007-01-01

Studies across a broad range of drainage basins have established a positive correlation between mean slope gradient and denudation rates. It has been suggested, however, that this relationship breaks down for catchments where slopes are at their threshold angle of stability because, in such cases, denudation is controlled by the rate of tectonic uplift through the rate of channel incision and frequency of slope failure. This mechanism is evaluated for the San Bernardino Mountains, California, a nascent range that incorporates both threshold hill-slopes and remnants of pre-uplift topography. Concentrations of in situ-produced cosmogenic 10Be in alluvial sediments are used to quantify catchment-wide denudation rates and show a broadly linear relationship with mean slope gradient up to ???30??: above this value denudation rates vary substantially for similar mean slope gradients. We propose that this decoupling in the slope gradient-denudation rate relationship marks the emergence of threshold topography and coincides with the transition from transport-limited to detachment-limited denudation. The survival in the San Bernardino Mountains of surfaces formed prior to uplift provides information on the topographic evolution of the range, in particular the transition from slope-gradient-dependent rates of denudation to a regime where denudation rates are controlled by rates of tectonic uplift. This type of transition may represent a general model for the denudational response to orogenic uplift and topographic evolution during the early stages of mountain building. ?? 2007 The Geological Society of America.

A geomorphic and tectonic model for the formation of the flight of Holocene marine terraces at Mahia Peninsula, New Zealand

NASA Astrophysics Data System (ADS)

Berryman, Kelvin; Clark, Kate; Cochran, Ursula; Beu, Alan; Irwin, Sarah

2018-04-01

At Table Cape, Mahia Peninsula, North Island, New Zealand, four marine terraces have been uplifted coseismically during the past 3500 years. Detailed facies assessment of the terrace coverbed sequence coupled with identification of modern analogues on the active shore platform were used to infer the process of marine terrace formation and to estimate the timing and amount of past uplift events (earthquakes). The modern platform can be subdivided into seven depositional zones: subtidal, outer platform, intertidal sand pockets, inner platform, high-tide, mid-storm, and storm beach. Terrace coverbeds were characterised from two trenches excavated across the full width of the uplifted terrace sequence. Off-lapping packages of high tidal, mid-storm, and storm beach sediments were most common. Outer platform sediments occurred only rarely near the base of some uplifted shore platforms. Overlying the marine sediments were near-horizontal terrestrial deposits of airfall tephra (on the two highest terraces), subsoil, topsoil, rare wedges of colluvial sediment (slopewash) shed from terrace risers, and an anomalous deposit possibly emplaced by a tsunami. Fifty-one radiocarbon ages, obtained from molluscs in the marine coverbeds, showed a general pattern of seaward-younging across the coastal plain and across each terrace and a less pronounced pattern of decreasing age upward in each coverbed sequence. The distinctive stepped geomorphology of the terraces, the facies and age structure of the terrace deposits and historical earthquake causation of similar terraces elsewhere in New Zealand provided the data to invoke an earthquake-driven model for terrace formation. Marine terrace development following an uplift event involved rapid cutting of a new intertidal shore platform and generally regressive deposition of high-tide to storm beach deposits. Following further uplift, the platform became a geomorphic terrace (above marine influence) and was then mantled by terrestrial sediments. On the two highest terraces at Table Cape, airfall tephras mantling the marine coverbeds provided a minimum age for terrace uplift. The youngest radiocarbon ages from high-tide deposits high in the stratigraphy and near the seaward edge of each terrace provided the best estimates for the timing of uplift. Based on the new radiocarbon ages and the constraining airfall tephra ages, we revised the earthquake ages to 3530-3350, 1810-1730, 1560-1300 and 300-100 cal. YBP. Associated best estimates of the coseismic uplift amounts were 2.1, 1.4, 1.8, and 3.1 m respectively, once we accounted for eustatic sea level changes through the late Holocene.

Feedbacks Between Channel Adjustment, Sediment Calibre and Landscape Dynamics in Tectonically Perturbed Landscapes (Invited)

NASA Astrophysics Data System (ADS)

Attal, M.; Cowie, P. A.; Whittaker, A. C.; Tucker, G. E.; Mudd, S. M.; Hurst, M. D.

2010-12-01

Knowledge of the coupling between channel geometry and sediment input to rivers is central to understanding the mechanisms and timescales over which landscapes respond to a tectonic perturbation. Here, we document changes to channel geometry and sediment calibre in catchments experiencing a well-constrained increase in relative uplift rate in the Central Apennines (Italy) and the Sierra Nevada (California). In both landscapes, channels and hillslopes steepen and knickpoints propagate upstream through the catchments, leading to the formation of a break in both hillslope and channel gradient that separates the steepened landscape from lower relief topography which has not yet responded to the change in uplift rate. Downstream of this break in slope, channels narrow markedly as river gradient increases. In addition, they are supplied with coarser sediment from the steepened hillslopes, in particular when sediment is supplied via landslides and debris fans. In Italy, channel narrowing can be explained using the equation proposed by Finnegan et al. [2005]: W = kQ3/8S-3/16, where W is channel width, k is a constant, Q is river discharge and S is channel slope. However, to model our field data, the prefactor k must be strongly dependent on uplift rate: the higher the uplift rate, the smaller the prefactor k. Using the Channel-Hillslope Integrated Landscape Development (CHILD) model, we show that the location of the main break in slope along the river profiles in Italy (in terms of height and along stream distance) can be fitted using a detachment-limited model with dynamic channel adjustment (equation above), k dependent on uplift rate and a threshold for erosion. A threshold corresponding to the shear stress required to entrain the median grain size of the sediment along the steepened reaches of the channels best fits the data. Our modelling results show that the response time of the landscape in this setting is strongly dependent on relative uplift rate, since knickpoint retreat rate in the detachment-limited model is a function of channel width and that the higher the relative uplift rate, the narrower the river. In a catchment uplifted at 1.5 mm/yr, knickpoint retreat rate can be up to 3 times higher than in a catchment uplifted at 0.25 mm/yr. This result is in agreement with measurements of knickpoint retreat rates using field data in the Apennines [Whittaker et al., 2008]. Steepened hillslopes along the rapidly incising Feather River, Sierra Nevada, California

The pitcher plant flesh fly exhibits a mixture of patchy and metapopulation attributes.

PubMed

Rasic, Gordana; Keyghobadi, Nusha

2012-01-01

We investigated the pattern of spatial genetic structure and the extent of gene flow in the pitcher plant flesh fly Fletcherimyia fletcheri, the largest member of the inquiline community of the purple pitcher plant Sarracenia purpurea. Using microsatellite loci, we tested the theoretical predictions of different hypothesized population models (patchy population, metapopulation, or isolated populations) among 11 bogs in Algonquin Provincial Park (Canada). Our results revealed that the pitcher plant flesh fly exhibits a mixture of patchy and metapopulation characteristics. There is significant differentiation among bogs and limited gene flow at larger spatial scales, but local populations do not experience frequent local extinctions/recolonizations. Our findings suggest a strong dispersal ability and stable population sizes in F. fletcheri, providing novel insights into the ecology of this member of a unique ecological microcosm.

Environmental factors explaining the vegetation patterns in a temperate peatland.

PubMed

Pellerin, Stéphanie; Lagneau, Louis-Adrien; Lavoie, Martin; Larocque, Marie

2009-08-01

Although ombrotrophic temperate peatlands are important ecosystems for maintaining biodiversity in eastern North America, the environmental factors influencing their flora are only partly understood. The relationships between plant species distribution and environmental factors were thus studied within the oldest temperate peatland of Québec. Plant assemblages were identified by cluster analysis while CCA was used to related vegetation gradients to environmental factors. Five assemblages were identified; three typical of open bog and two characterized by more minerotrophic vegetation. Thicker peat deposit was encounter underlying the bog assemblages while higher water table level and percentage of free surface water distinguished the minerotrophic assemblages. Overall, the floristic patterns observed were spatially structured along the margins and the expanse. The most important environmental factors explaining this spatial gradient were the percentage of free surface water and the highest water-table level.

SPRUCE Peat Physical and Chemical Characteristics from Experimental Plot Cores, 2012

DOE Data Explorer

Iversen, C. M. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; Hanson, P. J. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; Brice, D. J. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; Phillips, J. R. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; McFarlane, K. J. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; Hobbie, E. A. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; Kolka, R. K. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.

2012-01-01

This data set reports the results of physical and chemical analyses of peat core samples from the SPRUCE experimental study plots located in the S1-Bog. On August 13-15, 2012, a team of SPRUCE investigators and collaborators collected core samples of peat in the SPRUCE experimental plots. The goal was to characterize the biological, physical, and chemical characteristics of peat, and how those characteristics changed throughout the depth profile of the bog, prior to the initialization of the SPRUCE experimental warming and CO2 treatments. Cores were collected from 16 experimental plots; samples were collected from the hummock and hollow surfaces to depths of 200-300 cm in defined increments. Three replicate cores were collected from both hummock and hollow locations in each plot. The coring locations within each plot were mapped

The peats of Costa Rica (in English; Spanish)

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

Thayer, G.R.

Peat has been identified in Cost Rica, and an economic analysis of energy applications for peat has been done. About 1000 km{sup 2} of Cost Rica has the potential of being covered by peat. The Talamanca Mountains and the northeastern plains contain most of the Costa Rican peat. Specific bogs have been identified by the Medio Queso River in north-central Costa Rica and near El Cairo, Moin, and the Limon airport in northeastern Costa Rica. The Medio Queso bog, which is supplying peat for use as a carrier for nitrogen-fixing bacteria, and the El Cairo bog, which has been identifiedmore » as a source of horticultural peat for nearby ornamental plant farms, are of special interest. The economics of three energy applications of peat were examined -- as a fuel in large boilers, as a fuel in small boilers, and as an oil substitute in a cement plant. A facility using coal would have the same total costs as one using peat if coal prices were $45 and $30 per metric ton (used for large boilers and a cement plant, respectively). A facility using Bunker C or diesel would have the same total cost as one using peat if oil prices were $0.11, $0.08, and $0.06 per liter (used for large boilers, small boilers, and a cement plant, respectively). In all three cases, the costs for peat were comparable or less than the costs for coal and oil at 1987 prices. 6 refs., 8 figs.« less

Mapping raised bogs with an iterative one-class classification approach

NASA Astrophysics Data System (ADS)

Mack, Benjamin; Roscher, Ribana; Stenzel, Stefanie; Feilhauer, Hannes; Schmidtlein, Sebastian; Waske, Björn

2016-10-01

Land use and land cover maps are one of the most commonly used remote sensing products. In many applications the user only requires a map of one particular class of interest, e.g. a specific vegetation type or an invasive species. One-class classifiers are appealing alternatives to common supervised classifiers because they can be trained with labeled training data of the class of interest only. However, training an accurate one-class classification (OCC) model is challenging, particularly when facing a large image, a small class and few training samples. To tackle these problems we propose an iterative OCC approach. The presented approach uses a biased Support Vector Machine as core classifier. In an iterative pre-classification step a large part of the pixels not belonging to the class of interest is classified. The remaining data is classified by a final classifier with a novel model and threshold selection approach. The specific objective of our study is the classification of raised bogs in a study site in southeast Germany, using multi-seasonal RapidEye data and a small number of training sample. Results demonstrate that the iterative OCC outperforms other state of the art one-class classifiers and approaches for model selection. The study highlights the potential of the proposed approach for an efficient and improved mapping of small classes such as raised bogs. Overall the proposed approach constitutes a feasible approach and useful modification of a regular one-class classifier.

Distribution and speciation of mercury in the peat bog of Xiaoxing'an Mountain, northeastern China.

PubMed

Liu, Ruhai; Wang, Qichao; Lu, Xianguo; Fang, Fengman; Wang, Yan

2003-01-01

Most reports on mercury (Hg) in boreal ecosystems are from the Nordic countries and North America. Comparatively little information is available on Hg in wetlands in China. We present here a study on Hg in the Tangwang River forested catchment of the Xiaoxing'an Mountain in the northeast of China. The average total Hg (THg) in peat profile ranged from 65.8 to 186.6 ng g(-1) dry wt with the highest at the depth of 5-10 cm. THg in the peat surface was higher than the background in Heilongjiang province, the Florida Everglades, and Birkeness in Sweden. MethylHg (MeHg) concentration ranged from 0.16 to 1.86 ng g(-1) dry wt, with the highest amount at 10-15 cm depth. MeHg content was 0.2-1.2% of THg. THg and MeHg all decreased with the depth. THg in upland layer of soil (0-20 cm) was comparable to the peat surface, but in deeper layers THg concentration in peat was much higher than that in the forested mineral soil. THg in the peat bog increased, but MeHg decreased after it was drained. THg content in plant was different; THg contents in moss (119 ng g(-1) dry wt, n=12) were much higher than in the herbage, the arbor, and the shrubs. The peat bog has mainly been contaminated by Hg deposition from the atmosphere.

Paludification and forest retreat in northern oceanic environments.

PubMed

Crawford, R M M; Jeffree, C E; Rees, W G

2003-01-01

Examination of temperature variations over the past century for Europe and the Arctic from northern Norway to Siberia suggests that variations in the North Atlantic Oscillation are associated with an increase in oceanicity in certain maritime regions. A southward depression of the tree line in favour of wet heaths, bogs and wetland tundra communities is also observed in northern oceanic environments. The physiological basis for this change in ecological succession from forest to bog is discussed in relation to the long-term effects of flooding on tree survival. The heightened values currently detected in the North Atlantic Oscillation Index, together with rising winter temperatures, and increased rainfall in many areas in northern Europe, presents an increasing risk of paludification with adverse consequences for forest regeneration, particularly in areas with oceanic climates. Climatic warming in oceanic areas may increase the area covered by bogs and, contrary to general expectations, lead to a retreat rather than an advance in the northern limit of the boreal forest. High water-table levels are not automatically detrimental to forest survival as can be seen in swamp, bottom land and mangrove forests. Consequently, the inhibitory effects of flooding on tree survival and regeneration in northern regions should not be uncritically accepted as merely due to high water levels. Evidence is discussed which suggests that physiological and ecological factors may interact to inhibit forest regeneration in habitats where there is a risk of prolonged winter-flooding combined with warmer winters and cool moist summers.

Paludification and Forest Retreat in Northern Oceanic Environments

PubMed Central

CRAWFORD, R. M. M.; JEFFREE, C. E.; REES, W. G.

2003-01-01

Examination of temperature variations over the past century for Europe and the Arctic from northern Norway to Siberia suggests that variations in the North Atlantic Oscillation are associated with an increase in oceanicity in certain maritime regions. A southward depression of the treeline in favour of wet heaths, bogs and wetland tundra communities is also observed in northern oceanic environments. The physiological basis for this change in ecological succession from forest to bog is discussed in relation to the long‐term effects of flooding on tree survival. The heightened values currently detected in the North Atlantic Oscillation Index, together with rising winter temperatures, and increased rainfall in many areas in northern Europe, presents an increasing risk of paludification with adverse consequences for forest regeneration, particularly in areas with oceanic climates. Climatic warming in oceanic areas may increase the area covered by bogs and, contrary to general expectations, lead to a retreat rather than an advance in the northern limit of the boreal forest. High water‐table levels are not automatically detrimental to forest survival as can be seen in swamp, bottomland and mangrove forests. Consequently, the inhibitory effects of flooding on tree survival and regeneration in northern regions should not be uncritically accepted as merely due to high water levels. Evidence is discussed which suggests that physiological and ecological factors may interact to inhibit forest regeneration in habitats where there is a risk of prolonged winter‐flooding combined with warmer winters and cool moist summers. PMID:12509342

Mountain uplift explains differences in Palaeogene patterns of mammalian evolution and extinction between North America and Europe

PubMed Central

Eronen, Jussi T.; Janis, Christine M.; Chamberlain, C. Page; Mulch, Andreas

2015-01-01

Patterns of late Palaeogene mammalian evolution appear to be very different between Eurasia and North America. Around the Eocene–Oligocene (EO) transition global temperatures in the Northern Hemisphere plummet: following this, European mammal faunas undergo a profound extinction event (the Grande Coupure), while in North America they appear to pass through this temperature event unscathed. Here, we investigate the role of surface uplift to environmental change and mammalian evolution through the Palaeogene (66–23 Ma). Palaeogene regional surface uplift in North America caused large-scale reorganization of precipitation patterns, particularly in the continental interior, in accord with our combined stable isotope and ecometric data. Changes in mammalian faunas reflect that these were dry and high-elevation palaeoenvironments. The scenario of Middle to Late Eocene (50–37 Ma) surface uplift, together with decreasing precipitation in higher-altitude regions of western North America, explains the enigma of the apparent lack of the large-scale mammal faunal change around the EO transition that characterized western Europe. We suggest that North American mammalian faunas were already pre-adapted to cooler and drier conditions preceding the EO boundary, resulting from the effects of a protracted history of surface uplift. PMID:26041349

Denudation rates and tectonic geomorphology of the Spanish Betic Cordillera

NASA Astrophysics Data System (ADS)

Bellin, N.; Vanacker, V.; Kubik, P. W.

2014-03-01

The tectonic control on landscape morphology and long-term denudation is largely documented for settings with high uplift rates. Relatively little is known about the rates of geomorphic response in areas of low tectonic uplift. Here, we evaluate spatial variations in denudation of the Spanish Betic Cordillera based on cosmogenic 10Be-derived denudation rates. Denudation rates are compared to published data on rock uplift and exhumation of the Betic Cordillera to evaluate steady-state topography. The spatial patterns of catchment-wide denudation rates (n=20) are then analysed together with topographic metrics of hillslope and channel morphology. Catchments draining the Betic ranges have relatively low denudation rates (64±54 mm kyr), but also show large variation as they range from 14 to 246 mm kyr-1. Catchment-wide denudation is linearly proportional to the mean hillslope gradient and local relief. Despite large spatial variation in denudation, the magnitude and spatial pattern of denudation rates are generally consistent with longer-term local uplift rates derived from elevated marine deposits, fission-track measurements and vertical fault slip rates. This might be indicative of a steady-state topography where rock uplift is balanced by denudation.

A stable isotope record of late Cenozoic surface uplift of southern Alaska

NASA Astrophysics Data System (ADS)

Bill, Nicholas S.; Mix, Hari T.; Clark, Peter U.; Reilly, Sean P.; Jensen, Britta J. L.; Benowitz, Jeffrey A.

2018-01-01

Although the timing of an acceleration in late-Cenozoic exhumation of southern Alaska is reasonably well constrained as beginning ∼5-∼6 Ma, the surface uplift history of this region remains poorly understood. To assess the extent of surface uplift relative to rapid exhumation, we developed a stable isotope record using the hydrogen isotope composition (δD) of paleo-meteoric water over the last ∼7 Ma from interior basins of Alaska and Yukon Territory. Our record, which is derived from authigenic clays (δDclay) in silicic tephras, documents a ∼50-60‰ increase in δD values from the late Miocene (∼6-∼7 Ma) through the Plio-Pleistocene transition (∼2-∼3 Ma), followed by near-constant values over at least the last ∼2 Ma. Although this enrichment trend is opposite that of a Rayleigh distillation model typically associated with surface uplift, we suggest that it is consistent with indirect effects of surface uplift on interior Alaska, including changes in aridity, moisture source, and seasonality of moisture. We conclude that the δDclay record documents the creation of a topographic barrier and the associated changes to the climate of interior Alaska and Yukon Territory.

Widespread uplift and 'trapdoor' faulting on Galápagos volcanoes observed with radar interferometry.

PubMed

Amelung, F; Jónsson, S; Zebker, H; Segall, P

2000-10-26

Volcanic uplift, caused by the accumulation of magma in subsurface reservoirs, is a common precursor to eruptions. But, for some volcanoes, uplift of metres or more has not yet led to an eruption. Here we present displacement maps of volcanoes in the Galápagos Islands, constructed using satellite radar interferometry, that might help explain this dichotomy. We show that all but one of the seven volcanoes on the islands of Isabela and Fernandina deformed during 1992-99. Cerro Azul and Fernandina erupted during the observation period and show evidence of inflation, co-eruptive deflation and shallow dyke intrusion. In contrast, the largest volcano, Sierra Negra, has not erupted, yet exhibits spatially and temporally variable deformation, with a maximum uplift of 2.7 m between 1992 and 1999, which can be modelled by a shallow inflating sill. Inflation during 1997-98, however, was accompanied by 'trapdoor' faulting on a steeply dipping fracture system within the caldera. Repeated trapdoor faulting over geological time has formed an arcuate intra-caldera ridge within Sierra Negra and may have acted to relax stresses above the magma chamber, inhibiting summit eruptions. Similar processes may help explain large uplift unaccompanied by eruptive activity at other volcanoes.

River profile response to normal fault growth and linkage: an example from the Hellenic forearc of south-central Crete, Greece

NASA Astrophysics Data System (ADS)

Gallen, Sean F.; Wegmann, Karl W.

2017-02-01

Topography is a reflection of the tectonic and geodynamic processes that act to uplift the Earth's surface and the erosional processes that work to return it to base level. Numerous studies have shown that topography is a sensitive recorder of tectonic signals. A quasi-physical understanding of the relationship between river incision and rock uplift has made the analysis of fluvial topography a popular technique for deciphering relative, and some argue absolute, histories of rock uplift. Here we present results from a study of the fluvial topography from south-central Crete, demonstrating that river longitudinal profiles indeed record the relative history of uplift, but several other processes make it difficult to recover quantitative uplift histories. Prior research demonstrates that the south-central coastline of Crete is bound by a large ( ˜ 100 km long) E-W striking composite normal fault system. Marine terraces reveal that it is uplifting between 0.1 and 1.0 mm yr-1. These studies suggest that two normal fault systems, the offshore Ptolemy and onshore South-Central Crete faults, linked together in the recent geologic past (ca. 0.4-1 My BP). Fault mechanics predict that when adjacent faults link into a single fault the uplift rate in footwalls of the linkage zone will increase rapidly. We use this natural experiment to assess the response of river profiles to a temporal jump in uplift rate and to assess the applicability of the stream power incision model to this setting. Using river profile analysis we show that rivers in south-central Crete record the relative uplift history of fault growth and linkage as theory predicts that they should. Calibration of the commonly used stream power incision model shows that the slope exponent, n, is ˜ 0.5, contrary to most studies that find n ≥ 1. Analysis of fluvial knickpoints shows that migration distances are not proportional to upstream contributing drainage area, as predicted by the stream power incision model. Maps of the transformed stream distance variable, χ, indicate that drainage basin instability, drainage divide migration, and river capture events complicate river profile analysis in south-central Crete. Waterfalls are observed in southern Crete and appear to operate under less efficient and different incision mechanics than assumed by the stream power incision model. Drainage area exchange and waterfall formation are argued to obscure linkages between empirically derived metrics and quasi-physical descriptions of river incision, making it difficult to quantitatively interpret rock uplift histories from river profiles in this setting. Karst hydrology, break down of assumed drainage area discharge scaling, and chemical weathering might also contribute to the failure of the stream power incision model to adequately predict the behavior of the fluvial system in south-central Crete.

Middle Proterozoic uplift events in the Dunbar dome of northeastern Wisconsin, USA

USGS Publications Warehouse

Peterman, Z.E.; Sims, P.K.; Zartman, R.E.; Schulz, K.J.

1985-01-01

Isotopic ages of granitic and metamorphic rocks exposed in the Dunbar structural dome of northeastern Wisconsin identify a protracted series of tectonic and "hydrothermal" events that culminated in major regional uplift during Middle Proterozoic (Keweenawan; ca 1,100 Ma) continental rifting and volcanism. The major rock-forming events and the structural development of the dome occurred during the interval 1,862+/-4 Ma to 1,836+/-6 Ma. Whole-rock Rb-Sr ages are partly reset in response to a widely recognized but cryptic event in Wisconsin and Michigan at about 1,630 Ma. The scale and systematic character of the whole-rock resetting strongly suggests the presence of a fluid phase derived in situ from water dissolved in the silicates or externally from a subthrust plate of low-grade metamorphic rocks. The regional nature of the 1,630-Ma disturbance possibly indicates that it is related to a major tectonic event such as an active plate margin far to the south. Rb-Sr biotite ages for the Dunbar dome (this study), the southern complex of the Marquette district (Van Schmus and Woolsey 1975) and the Felch trough area (Aldrich and others 1965) provide a remarkably coherent pattern that reflects multiple episodes of differential uplift. Younger events superimposed on a regional 1,630-Ma imprint are recorded at 1,330 Ma and 1,140 Ma. The 1,330 Ma disturbance could reflect stabilization following intrusion of the Wolf River batholith at 1,485 Ma. The 1,140-Ma uplift event occurred during Keweenawan rifting and volcanism as a result of stresses imposed on a mosaic of fault-bounded blocks with possible subcrustal influence. The remarkably small variance in the 1,140-Ma biotite age peak argues for rapid uplift and cooling, and hence rapid erosion. Detritus from the uplift probably was being shed into nearby tectonic basins most of which did not survive subsequent uplift and erosion. ?? 1985 Springer-Verlag.

Constraining the age and magnitude of uplift in the northern National Petroleum Reserve in Alaska (NPRA)-apatite fission-track analysis of samples from three wells

USGS Publications Warehouse

Houseknecht, David W.; Bird, Kenneth J.; O'Sullivan, Paul

2011-01-01

A broad, post-mid-Cretaceous uplift is defined in the northern National Petroleum Reserve in Alaska (NPRA) by regional truncation of Cretaceous strata, thermal maturity patterns, and amounts of exhumation estimated from sonic logs. Apatite fission-track (AFT) analysis of samples from three wells (South Meade No. 1, Topagoruk No. 1, and Ikpikpuk No. 1) across the eastern flank of the uplift indicates Tertiary cooling followed by Quaternary heating. Results from all three wells indicate that cooling, presumably caused by uplift and erosion, started about 75-65 Ma (latest Cretaceous-earliest Tertiary) and continued through the Tertiary Period. Data from South Meade indicate more rapid cooling after about 35-15 Ma (latest Eocene-middle Miocene) followed by a significant increase in subsurface temperature during the Quaternary, probably the result of increased heat flow. Data from Topagoruk and Ikpikpuk include subtle evidence of accelerated cooling starting in the latest Eocene-middle Miocene and possible evidence of increased temperature during the Quaternary. Subsurface temperature perturbations related to the insulating effect of permafrost may have been responsible for the Quaternary temperature increase at Topagoruk and Ikpikpuk and may have been a contributing factor at South Meade. Multiple lines of geologic evidence suggest that the magnitude of exhumation resulting from uplift and erosion is 5,000-6,500 ft at South Meade, 4,000-5,500 ft at Topagoruk, and 2,500-4,000 ft at Ikpikpuk. The results from these wells help to define the broad geometry of the uplift, which increases in magnitude from less than 1,000 ft at the Colville River delta to perhaps more than 7,000 ft along the northwestern coast of NPRA, between Point Barrow and Peard Bay. Neither the origin nor the offshore extent of the uplift, west and north of the NPRA coast, have been determined.

Time-varying interseismic strain rates and similar seismic ruptures on the Nias-Simeulue patch of the Sunda megathrust

USGS Publications Warehouse

Meltzner, Aron J.; Sieh, Kerry E.; Chiang, Hong-Wei; Wu, Chung-Che; Tsang, Louisa L.H.; Shen, Chuan-Chou; Hill, Emma M.; Suwargadi, Bambang W.; Natawidjaja, Danny H.; Philibosian, Belle; Briggs, Richard

2015-01-01

Fossil coral microatolls from fringing reefs above the great (MW 8.6) megathrust rupture of 2005 record uplift during the historically reported great earthquake of 1861. Such evidence spans nearly the entire 400-km strike length of the 2005 rupture, which was previously shown to be bounded by two persistent barriers to seismic rupture. Moreover, at sites where we have constrained the 1861 uplift amplitude, it is comparable to uplift in 2005. Thus the 1861 and 2005 ruptures appear to be similar in both extent and magnitude. At one site an uplift around AD 1422 also appears to mimic the amount of uplift in 2005. The high degree of similarity among certain ruptures of this Nias–Simeulue section of the Sunda megathrust contrasts with the substantial disparities amongst ruptures along other sections of the Sumatran portion of the Sunda megathrust. At a site on the northwestern tip of Nias, reefs also rose during an earthquake in AD 1843, known historically for its damaging tsunami along the eastern coast of the island.The coral microatolls also record interseismic vertical deformation, at annual to decadal resolution, spanning decades to more than a century before each earthquake. The corals demonstrate significant changes over time in the rates of interseismic deformation. On southern Simeulue, interseismic subsidence rates were low between 1740 and 1820 but abruptly increased by a factor of 4–10, two to four decades before the 1861 rupture. This may indicate that full coupling or deep locking of the megathrust began only a few decades before the great earthquake. In the Banyak Islands, near the pivot line separating coseismic uplift from subsidence in 2005, ongoing interseismic subsidence switched to steady uplift from 1966 until 1981, suggesting a 15-year-long slow slip event, with slip velocities at more than 120% of the plate convergence rate

Erosive processes after tectonic uplift stimulate vicariant and adaptive speciation: evolution in an Afrotemperate-endemic paper daisy genus

PubMed Central

2014-01-01

Background The role of tectonic uplift in stimulating speciation in South Africa’s only alpine zone, the Drakensberg, has not been explicitly examined. Tectonic processes may influence speciation both through the creation of novel habitats and by physically isolating plant populations. We use the Afrotemperate endemic daisy genus Macowania to explore the timing and mode (geographic versus adaptive) of speciation in this region. Between sister species pairs we expect high morphological divergence where speciation has happened in sympatry (adaptive) while with geographic (vicariant) speciation we may expect to find less morphological divergence and a greater degree of allopatry. A dated molecular phylogenetic hypothesis for Macowania elucidates species’ relationships and is used to address the potential impact of uplift on diversification. Morphological divergence of a small sample of reproductive and vegetative characters, used as a proxy for adaptive divergence, is measured against species’ range distributions to estimate mode of speciation across two subclades in the genus. Results The Macowania crown age is consistent with the hypothesis of post-uplift diversification, and we find evidence for both vicariant and adaptive speciation between the two subclades within Macowania. Both subclades exhibit strong signals of range allopatry, suggesting that geographic isolation was important in speciation. One subclade, associated with dry, rocky environments at high altitudes, shows very little morphological and ecological differentiation but high range allopatry. The other subclade occupies a greater variety of habitats and exhibits far greater morphological differentiation, but contains species with overlapping distribution ranges. Conclusions Species in Macowania are likely to have diversified in response to tectonic uplift, and we invoke uplift and uplift-mediated erosion as the main drivers of speciation. The greater relative morphological divergence in sympatric species of Macowania indicates that speciation in the non-sympatric taxa may not have required obvious adaptive differences, implying that simple geographic isolation was the driving force for speciation (‘neutral speciation’). PMID:24524661

Temporal and Spatial Evolution of Dynamic Support From River Profiles: A Framework for Madagascar and Africa

NASA Astrophysics Data System (ADS)

Paul, J. D.; Roberts, G. G.; White, N.

2012-04-01

It is generally accepted that the surface topography of Africa is a manifestation of convective circulation in the sub-lithospheric mantle. Here, we present an inverse method whereby longitudinal river profiles are interrogated to extract quantitative estimates of spatial and temporal variations in the rate of tectonic uplift. Surface processes can provide an important window into transient convective circulation in the sub-lithospheric mantle. River profiles act as 'tectonic tape recorders': we assume the generation of broad, convex-upward knickzones to represent the effect of tectonic uplift shifting the river system into a state of disequilibrium. Profiles evolve through time primarily via the headward retreat of these knickzones. We use a conjugate gradient inverse algorithm to minimise the misfit between observed river profiles - derived from a regional Digital Elevation Model (DEM) - and calculated profiles obtained by varying the uplift rate history. We jointly invert a total of 98 Malagasy and 570 African river profiles to obtain a history of the cumulative tectonic uplift through geological time. We show that Africa has undergone two phases of rapid uplift: first in Eocene times; secondly, since 10 Ma. While the first gave rise to broad, long wavelength topography, the second led to more localised domal swells of high relief. We propose the existence of two wavelengths of dynamic support, reflecting a change in the style of convection in the upper mantle since 50 Ma. Our results correlate strongly with independent geological estimates of uplift across Africa and Madagascar, while our calculated landscape surface following 50 Myr of uplift corresponds closely to a surface fit across present-day drainage divides. Finally we calculate the solid sediment flux delivered to major African deltas as a function of time. This onshore record provides an important indirect constraint on the history of vertical motions at the surface, and agrees well with the offshore flux record, obtained from mapping the thickness of chronostratigraphic sediment packages at the deltas.

Late Quaternary uplift rate inferred from marine terraces, Shimokita Peninsula, northeastern Japan: A preliminary investigation of the buried shoreline angle

NASA Astrophysics Data System (ADS)

Matsu'ura, Tabito; Kimura, Haruo; Komatsubara, Junko; Goto, Norihisa; Yanagida, Makoto; Ichikawa, Kiyoshi; Furusawa, Akira

2014-03-01

After estimating tectonic uplift rates along the northern part of the northeast Japan forearc (the overriding plate in the northeast Japan subduction zone) by mapping the elevation of the inner edges of marine terrace surfaces, we refined this estimate through elevation measurements of the buried shoreline angle beneath well-dated marine terrace surfaces, from which we could derive more accurate paleo-sea levels. The uplift rate initially inferred from the inner edge of marine terrace T4, correlated with marine isotope stage MIS 5e by tephrochronology, increases eastward from 0.11-0.22 m ky- 1 around the backarc volcanic front to 0.17-0.32 m ky- 1 in the forearc on the peninsula of Shiriyazaki. We refined the uplift rates for T4, on the basis of the shoreline angle elevation, from the reconstructed profile of the paleo-sea cliff and wave-cut platform on a rocky coast and the reconstructed profile of the swash zone sediments and terrace deposits on a sandy coast. The refined uplift rates were 0.14-0.25 m ky- 1 on the rocky coast and 0.14-0.23 m ky- 1 on the sandy coast, slightly slower than the rates we inferred from the height of T4 and about one-half to three-fourths of previously reported rates. By extrapolation from the example of the sandy coast, the refined uplift rate around the volcanic front was 0.09-0.18 m ky- 1. The vertical deformation across the forearc of the Shimokita Peninsula since MIS 5e is possibly associated with regional isostatic uplift of 0.09-0.18 m ky- 1 and anticlinal deformation by an offshore fault, interpreted from acoustic profiles, of 0.05-0.07 m ky- 1.

Post-glacial inflation-deflation cycles, tilting, and faulting in the Yellowstone Caldera based on Yellowstone Lake shorelines

USGS Publications Warehouse

Pierce, Kenneth L.; Cannon, Kenneth P.; Meyer, Grant A.; Trebesch, Matthew J.; Watts, Raymond D.

2002-01-01

The Yellowstone caldera, like many other later Quaternary calderas of the world, exhibits dramatic unrest. Between 1923 and 1985, the center of the Yellowstone caldera rose nearly one meter along an axis between its two resurgent domes (Pelton and Smith, 1979, Dzurisin and Yamashita, 1987). From 1985 until 1995-6, it subsided at about two cm/yr (Dzurisin and others, 1990). More recent radar interferometry studies show renewed inflation of the northeastern resurgent dome between 1995 and 1996; this inflation migrated to the southwestern resurgent dome from 1996 to 1997 (Wicks and others, 1998). We extend this record back in time using dated geomorphic evidence of postglacial Yellowstone Lake shorelines around the northern shore, and Yellowstone River levels in the outlet area. We date these shorelines using carbon isotopic and archeological methods. Following Meyer and Locke (1986) and Locke and Meyer (1994), we identify the modern shoreline as S1 (1.9 ? 0.3 m above the lake gage datum), map paleoshoreline terraces S2 to S6, and infer that the prominent shorelines were cut during intracaldera uplift episodes that produced rising water levels. Doming along the caldera axis reduces the gradient of the Yellowstone River from Le Hardys Rapids to the Yellowstone Lake outlet and ultimately causes an increase in lake level. The 1923-1985 doming is part of a longer uplift episode that has reduced the Yellowstone River gradient to a ?pool? with a drop of only 0.25 m over most of this 5 km reach. We also present new evidence that doming has caused submergence of some Holocene lake and river levels. Shoreline S5 is about 14 m above datum and estimated to be ~12.6 ka, because it post-dates a large hydrothermal explosion deposit from the Mary Bay area (MB-II) that occurred ~13 ka. S4 formed about 8 m above datum ~10.7 ka as dated by archeology and 14C, and was accompanied by offset on the Fishing Bridge fault. About 9.7 ka, the Yellowstone River eroded the ?S-meander?, followed by a ~5 m rise in lake level to S2. The lowest generally recognizable shoreline is S2. It is ~5 m above datum (3 m above S1) and is ~8 ka, as dated on both sides of the outlet. Yellowstone Lake and the river near Fishing Bridge were 5-6 m below their present level about 3-4 ka, as indicated by 14C ages from submerged beach deposits, drowned valleys, and submerged Yellowstone River gravels. Thus, the lake in the outlet region has been below or near its present level for about half the time since a 1 km-thick icecap melted from the Yellowstone Lake basin about 16 ka. The amplitude of two rises in lake and river level can be estimated based on the altitude of Le Hardys Rapids, indicators of former lake and river levels, and reconstruction of the river gradient from the outlet to Le Hardys Rapids. Both between ~9.5 ka and ~8.5 ka, and after ~3 ka, Le Hardys Rapids (LHR) was uplifted about 8 meters above the outlet, suggesting a cyclic deformation process. Older possible rises in lake level are suggested by locations where the ~10.7 ka S4 truncates older shorelines, and valleys truncated by the ~12.6 ka S5 shoreline. Using these controls, a plot of lake level through time shows 5-7 millennial-scale oscillations since 14.5 ka. Major cycles of inflation and deflation are thousands of years long. Le Hardys Rapids has twice been uplifted ~8 m relative to the lake outlet. These two locations span only the central 25% of the historic caldera doming, so that if we use historic doming as a model, total projected uplift would be ~32 m. This ?heavy breathing? of the central part of the Yellowstone caldera may reflect a combination of several possible processes: magmatic inflation, tectonic stretching and deflation, and hydrothermal fluid sealing and inflation followed by cracking of the seal, pressure release, and deflation. Over the entire postglacial period, subsidence has balanced or slightly exceeded uplift as shown by older shorelines that descend towards the caldera axis. We

Local magnetic fields, uplift, gravity, and dilational strain changes in Southern California ( USA).

USGS Publications Warehouse

Johnston, M.J.S.

1986-01-01

Measurements of regional magnetic field near the San Andreas fault at Cajon, Palmdale and Tejon are strongly correlated with changes in gravity, areal strain, and uplift in these regions during the period 1977-1984. Because the inferred relationships between these parameters are in approximate agreement with those obtained from simple deformation models, the preferred explanation appeals to short-term strain episodes independently detected in each data set. Transfer functions from magnetic to strain, gravity, and uplift perturbations, obtained by least-square linear fits to the data, are -0.98 nT/ppm, -0.03 nT/mu Gal, and 9.1 nT/m respectively. Tectonomagnetic model calculations underestimate the observed changes and those reported previously for dam loading and volcano-magnetic observations. A less likely alternative explanation of the observed data appeals to a common source of meteorologically generated crustal or instrumental noise in the strain, gravity, magnetic, and uplift data.-from Author

Uplift and subsidence reveal a nonpersistent megathrust rupture boundary (Sitkinak Island, Alaska)

USGS Publications Warehouse

Briggs, Richard W.; Engelhart, Simon E.; Nelson, Alan R.; Dura, Tina; Kemp, Andrew C.; Haeussler, Peter J.; Corbett, D. Reide; Angster, Stephen J.; Bradley, Lee-Ann

2014-01-01

We report stratigraphic evidence of land-level change and tsunami inundation along the Alaska-Aleutian megathrust during prehistoric and historical earthquakes west of Kodiak Island. On Sitkinak Island, cores and tidal outcrops fringing a lagoon reveal five sharp lithologic contacts that record coseismic land-level change. Radiocarbon dates, 137Cs profiles, CT scans, and microfossil assemblages are consistent with rapid uplift ca. 290-0, 520-300, and 1050-790 cal yr BP, and subsidence in AD 1964 and ca. 640-510 cal yr BP. Radiocarbon, 137Cs, and 210Pb ages bracketing a sand bed traced 1.5 km inland and evidence for sudden uplift are consistent with Russian accounts of an earthquake and tsunami in AD 1788. The mixed uplift and subsidence record suggests that Sitkinak Island sits above a non-persistent boundary near the southwestern limit of the AD 1964 Mw 9.2 megathrust rupture.

Quarternary evolution of fluvial systems in the northern Rio Grande rift: Implications for vertical crustal uplift and rift tectonics. Final report, October 1, 1988--September 30, 1989

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

Harrington, C.D.; Wells, S.G.

1994-09-01

We propose to establish the late Cenozoic history of incision of the Rio Grande in the northern rift and to relate the variations of drainage incision to vertical uplift and rift tectonics. Our objectives are to establish the nature and timing of Rio Grande gorge development across the boundary between the Espanola/Taos-San Luis basins using isotopic and varnish cation ratio dating, establishing isochrons along gorge walls and isoleths of incision rates throughout the gorge, and documenting spatial and temporal variations in the isopleth data that might reflect deformation resulting from crustal uplift. The results of this study will be significantmore » because the derived isochrons and incision rates can be used to date periods and to document the areal extent of vertical crustal uplift which may reflect asthenospheric and lithospheric interactions beneath the rift.« less

Isostatic and dynamic support of high topography on a North Atlantic passive margin

NASA Astrophysics Data System (ADS)

Pedersen, Vivi K.; Huismans, Ritske S.; Moucha, Robert

2016-07-01

Substantial controversy surrounds the origin of high topography along passive continental margins. Here we focus on the well-documented elevated passive margin in southwestern Scandinavia, and quantify the relative contributions of crustal isostasy and dynamic topography in controlling the present topography. We find that majority of the topography is compensated by the crustal structure, suggesting a topographic age that is in accord with the 400 Myr old Caledonian orogenesis. In addition, we propose that dynamic uplift of ∼300 m has rejuvenated existing topography locally in the coastal region over the last 10 Myr. Such uplift, combined with a general sea level fall, can help explain a variety of observations that have traditionally been interpreted in favor of a peneplain uplift model. We conclude that high topography along the Scandinavian margin cannot represent remnants of a peneplain uplifted within the last 20 Myr. The topography must have been high since the Caledonian orogeny.

Renewed uplift of the Central Andes Forearc revealed by coastal evolution during the Quaternary

NASA Astrophysics Data System (ADS)

Regard, Vincent; Saillard, Marianne; Martinod, Joseph; Audin, Laurence; Carretier, Sébastien; Pedoja, Kevin; Riquelme, Rodrigo; Paredes, Paola; Hérail, Gérard

2010-08-01

Most of the Pacific coast of the Central Andes, between 15°S and 30°S, display a wide (a couple of kilometres) planar feature, gently dipping oceanwards and backed by a cliff. This morphology, usually of marine origin, is called rasa, and argues for a recent and spatially continuous uplift of the margin over the 1500-km-long coastal region we describe. The cliff foot is found at a similar elevation (˜ 110 m amsl) all over the studied area, with the exception of peninsulas such as the Mejillones Peninsula. The compilation of published chronological data and the extrapolation of re-appraised uplift rates provide evidence for a common cliff foot age of around 400 ka (i.e., Marine Isotopic Stage MIS 11). This, together with other geological constraints, indicates a Quaternary renewal of uplift in the Central Andes Forearc after a late Pliocene quiescence or subsidence.

Buoyancy, Uplift, and AGN Feedback - Deep Chandra and XMM-Newton Observations of the Radio Outbursts in NGC 4472 and NGC 1399

NASA Astrophysics Data System (ADS)

Kraft, R.; Su, Y.; Gendron Marsolais, M.; Roediger, E.; Nulsen, P.; Hlavacek-Larrondo, J.; Forman, W.; Jones, C.; Randall, S.; Machacek, M.

2017-10-01

We present results from deep Chandra and XMM-Newton observations of the AGN outbursts in the nearby early-type galaxies NGC 4472 and NGC 1399. Both pairs of radio bubbles are surrounded by rims of enhanced X-ray emission. Spectral analysis shows that the temperatures of these rims are less than that of the surrounding medium, suggesting that they are gas uplifted from the group center by the buoyant rise of the radio bubbles and not shocks due to the supersonic inflation of the lobes. The energy required to uplift these shells can be a significant fraction of the total outburst energy, and thus may play an important role in the thermodynamic evolution of the galaxy core. Buoyant uplift could also be a very efficient means of transporting metals from the galaxy core to the halo.

Drip tectonics and the enigmatic uplift of the Central Anatolian Plateau.

PubMed

Göğüş, Oğuz H; Pysklywec, Russell N; Şengör, A M C; Gün, Erkan

2017-11-16

Lithospheric drips have been interpreted for various regions around the globe to account for the recycling of the continental lithosphere and rapid plateau uplift. However, the validity of such hypothesis is not well documented in the context of geological, geophysical and petrological observations that are tested against geodynamical models. Here we propose that the folding of the Central Anatolian (Kırşehir) arc led to thickening of the lithosphere and onset of "dripping" of the arc root. Our geodynamic model explains the seismic data showing missing lithosphere and a remnant structure characteristic of a dripping arc root, as well as enigmatic >1 km uplift over the entire plateau, Cappadocia and Galatia volcanism at the southern and northern plateau margins since ~10 Ma, respectively. Models show that arc root removal yields initial surface subsidence that inverts >1 km of uplift as the vertical loading and crustal deformation change during drip evolution.

Ongoing Uplift Rates and Topography Across the Aleutian Forearc Region on Kodiak Island, Alaska.

NASA Astrophysics Data System (ADS)

Sauber, J. M.; Carver, G. A.

2002-12-01

The Kodiak Islands are part of a large subduction complex that comprises the eastern Aleutian forearc; the islands form the subaerial part of a broad topographic ridge that includes a Mesozoic-Cenozoic accretionary complex. To explore the relation between the ongoing subduction process, uplift rates and topographic characteristics, we have used a 30 m digital elevation map (DEM) derived from the Shuttle Radar Topography Mission (SRTM), an older 90 m DEM and ocean bathymetry. The topographic characteristics of Kodiak Island vary along strike and as a function of distance from the trench. From the northern to southern part of island, the distance from the 5800 m bathymetric contour (Aleutian Trench) and the eastern coast of Kodiak Island, as well as the width of the island, narrows by about 10% and probably reflects a steepening of the dip of the downgoing Pacific plate under the southern part of the island. The northern and central part of the island have similar topographic profiles as a function of distance from the trench; the highest peaks are located in the central part of the island. Although most of the island was glaciated during the last glacial maximum, the southwest portion of the island remained unglaciated; this region is distinctly less dissected. Preliminary uplift rates across the forearc region have been estimated from coastal marine terraces and short-term geodetic observations. Elevation changes over the last 103 - 104 years are being obtained from kinematic GPS observations across two sets of Holocene marine terrace sequences and from elevation measurements in northern Kodiak of an extensive late Pleistocene marine terrace (probably an oxygen isotope stage 5a, 120 - 130 ka). Initial measurements from the older terrace in northern Kodiak suggest an average uplift rate for the eastern side of Kodiak, above the down-dip end of the locked zone on the megathrust, to be about 1.2 mm/yr; on the western side of the island the uplift rate decreases by an order of magnitude. GPS observations of short-term uplift rates from a northern Kodiak geodetic network [Sauber et al.,2002] and a southern Kodiak geodetic network, (Katmai network of Savage et al., 1999), indicate similar uplift rates of 2-5 mm/yr along the eastern coast, 9-11 mm/yr near the city of Kodiak and 3-5 mm/yr along the western coast. These geodetically determined rates are an order of magnitude greater than the long-term rates derived from the raised coastal terraces. Numerical modeling of both sets of observations suggest that these short-term uplift rates are primarily due to interseismic strain associated with a shallow, locked, main thrust zone and down-dip, post-seismic processes following the 1964 earthquake, while the long-term rates include both interseismic and coseismic vertical motions over many seismic cycles. Except for the extreme eastern side of the island where active upper plate faults are present, uplift, as reflected by the elevation of the late Pleistocene marine terraces, decreases toward the west at a relatively uniform rate over long trench-normal distances. The region of highest short-term uplift does correspond to the region of highest topography. However, the elevation of the marine terraces on the eastern margin of the island indicate late Quaternary faulting and folding produce localized areas of anomalously high rates of uplift.

Episodes of subsidence and uplift of the conjugate margins of Greenland and Norway after opening of the NE Atlantic

NASA Astrophysics Data System (ADS)

Japsen, Peter; Green, Paul F.; Bonow, Johan M.; Chalmers, James A.

2016-04-01

We have undertaken a regional study of the thermo-tectonic development of East Greenland (68-75°N; Bonow et al. 2014; Japsen et al. 2014) and of southern Norway (58-64°N) based on integration of apatite fission-track analysis (AFTA), stratigraphic landscape analysis and the geological record onshore and offshore. Volcanic and sedimentary rocks accumulated on the subsiding, East Greenland margin during and following breakup and then began to be exhumed during late Eocene uplift that preceded a major, early Oligocene plate reorganization in the NE Atlantic. The Norwegian margin also experienced Eocene subsidence and burial; there are hemipelagic, deep-marine sediments of Eocene age along the coast of southern Norway. End-Eocene uplift of the NW European margin led to the formation of a major unconformity along the entire margin and to progradation of clastic wedges from Norway towards the south. Our AFTA data from East Greenland and southern Norway reveal a long history of Mesozoic burial and exhumation across the region, with a number of broadly synchronous events being recorded on both margins. AFTA data from East Greenland show clear evidence for uplift at the Eocene-Oligocene transition whereas the data from Norway do not resolve any effects of exhumation related to this event. AFTA data from the East Greenland margin show evidence of two Neogene events of uplift and incision of the in the late Miocene and Pliocene whereas results from southern Norway define Neogene uplift and erosion which began in the early Miocene. A Pliocene uplift phase in southern Norway is evident from the stratigraphic landscape analysis and from the sedimentary sequences offshore. In East Greenland, a late Eocene phase of uplift led to formation of a regional erosion surface near sea level (the Upper Planation Surface, UPS). Uplift of the UPS in the late Miocene led to formation of the Lower Planation Surface (LPS) by incision below the uplifted UPS, and a Pliocene phase led to incision of valleys and fjords below the uplifted LPS, leaving mountain peaks reaching 3.7 km above sea level. In southern Norway (as also in southern Sweden), the sub-horizontal Palaeic surfaces truncate the tilted, sub-Mesozoic erosion surface along the coasts. Lidmar-Bergström et al. (2013) used this relationship to conclude that the Palaeic relief is of Cenozoic age. In Greenland, definition of the chronology of events benefits from the availability of AFTA data from boreholes onshore where the plateau surfaces truncate Palaeogene basalts, and thus make it possible to date formation of these surfaces and correlate them with offshore unconformities. In Norway, the absence of post-rift rocks onshore precludes such integrated analysis. However, the presence of offshore unconformities, coupled with similar onshore landscapes and Cenozoic cooling history suggest a similar overall style of evolution. The similarities between the two margins lead us to us suggest that these margins developed in broadly similar fashion, and that the mountains of Norway also reached their present elevation long after Atlantic breakup. Bonow, Japsen, Nielsen 2014. Global and Planetary Change 116. Japsen, Green, Bonow, Nielsen, Chalmers 2014. Global and Planetary Change 116. Lidmar-Bergström, Bonow, Japsen 2013. Global and Planetary Change 100.

Geomorphological evolution of western Sicily, Italy

NASA Astrophysics Data System (ADS)

Di Maggio, Cipriano; Madonia, Giuliana; Vattano, Marco; Agnesi, Valerio; Monteleone, Salvatore

2017-02-01

This paper proposes a morphoevolutionary model for western Sicily. Sicily is a chain-foredeep-foreland system still being built, with tectonic activity involving uplift which tends to create new relief. To reconstruct the morphoevolutionary model, geological, and geomorphological studies were done on the basis of field survey and aerial photographic interpretation. The collected data show large areas characterized by specific geological, geomorphological, and topographical settings with rocks, landforms, and landscapes progressively older from south to north Sicily. The achieved results display: (1) gradual emersion of new areas due to uplift, its interaction with the Quaternary glacio-eustatic oscillations of the sea level, and the following production of a flight of stair-steps of uplifted marine terraces in southern Sicily, which migrates progressively upward and inwards; in response to the uplift (2) triggering of down-cutting processes that gradually dismantle the oldest terraces; (3) competition between uplift and down-cutting processes, which is responsible for the genesis of river valleys and isolated rounded hills in central Sicily; (4) continuous deepening over time that results in the exhumation of older and more resistant rocks in northern Sicily, where the higher heights of Sicily are realized and the older forms are retained; (5) extensional tectonic event in the northern end of Sicily, that produces the collapse of large blocks drowned in the Tyrrhenian Sea and sealed by coastal-marine deposits during the Calabrian stage; (6) trigger of uplift again in the previously subsiding blocks and its interaction with coastal processes and sea level fluctuations, which produce successions of marine terraces during the Middle-Upper Pleistocene stages.

The Waqf as Suwwan crater, Eastern Desert of Jordan: aspects of the deep structure of an oblique impact from reflection seismic and gravity data

NASA Astrophysics Data System (ADS)

Heinrichs, Till; Salameh, Elias; Khouri, Hani

2014-01-01

The deeply eroded Waqf as Suwwan ring structure was recently discovered to be a large impact, the first identified in the near east. Large-scale reflection seismic structure shows the impact situated high on the northeastern flank of the Jordan Uplift sloping into Wadi Sirhan Basin. If exhumation is linked to the Arabia-Eurasia collision, a likely time window for the impact event may be latest Eocene to Late Oligocene. Impact into a shallow sea seems an optional scenario. Old reflection seismic lines offer limited insight into the deep structure of the rim and part of the central uplift of the complex crater. An important structural clue is provided by a well-resolved seismic horizon of a yet tentative correlation with a Paleozoic black shale. The central gravity high is compatible with a mass surplus by the uplift of denser Paleozoic basement below the central uplift. The gravity model further indicates a ring of dense Paleozoic sediments rising from below into the ring syncline. Seismics show presumably radial synclines in the central uplift which are interpreted by centripetal constrictional flow during crater collapse. Beneath the final crater's outer boundary, a shallow-dip normal fault zone, subtle seismic structure in uncollapsed footwall segments reveal an asymmetry of strain. The asymmetry is attributed to the cratering flow by an oblique impact directed toward NE. The finding provides independent support to an earlier suggestion of impact obliquity based on vergency of folds exposed on the central uplift.

Seventeenth-century uplift in eastern Hokkaido, Japan

USGS Publications Warehouse

Atwater, B.F.; Furakawa, R.; Hemphill-Haley, E.; Ikeda, Y.; Kashima, K.; Kawase, K.; Kelsey, H.M.; Moore, A.L.; Nanayama, F.; Nishimura, Y.; Odagiri, S.; Ota, Y.; Park, S.-C.; Satake, K.; Sawai, Y.; Shimokawa, K.

2004-01-01

Shores of eastern Hokkaido rose by perhaps 1 m a few centuries ago. The uplifted area extended at least 50 km along the southern Kuril Trench. It included the estuaries Akkeshi-ko and Hichirippu, on the Pacific coast, and Fu??ren-ko and Onneto??, which open to the Okhotsk Sea. At each estuary, intertidal and subtidal flats rose with respect to tide level; wetland plants colonized the emerging land; and peaty wetland deposits thereby covered mud and sand of the former flats. Previous work at Akkeshi-ko and Onneto?? showed that such emergence occurred at least three times in the past 3000 years. Volcanic-ash layers date the youngest emergence to the seventeenth century AD. New evidence from Akkeshi-ko, Hichirippu and Fu??ren-ko clarifies the age and amount of this youngest emergence. Much of it probably dates from the century's middle decades. Some of the newly emerged land remained above high tides into the middle of the eighteenth century or later. The emergence in the last half of the seventeenth century probably exceeded 0.5 m (inferred from stratigraphy and diatom palaeoecology) without far exceeding 1 m (estimated by comparing seventeenth- and eighteenth-century descriptions of Akkeshi-ko). The stratigraphy and palaeoecology of the emergence are better explained by tectonic uplift than by bay-mouth blockage, tidal-flat accretion or sea-level fall. Eastern Hokkaido needs occasional uplift, moreover, to help reconcile its raised marine terraces with its chronic twentieth-century subsidence. Because it took place above forearc mantle, eastern Hokkaido's seventeenth-century uplift probably lacks analogy with coseismic uplift that occurs above typical plate-boundary ruptures at subduction zones.

Origin and structural development of the LaSalle Arch, Louisiana

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

Lawless, P.N.

1990-05-01

The LaSalle arch is a basement high separating the Louisiana and Mississippi interior salt basins. Using reflection seismic data, an area located on the southern end of the LaSalle arch was shown to be composed of relict Paleozoic continental crust that was left behind and partially rifted during the breakup of Pangea during the Triassic. Rifting preferentially occurred to the north of a Paleozoic thrust fault nose, and crustal extension took place in a northeast-southwest direction. The LaSalle arch, as seen in post-Triassic stratigraphy, formed by a two-part process. The western limb developed syndepositionally due to differential subsidence, and themore » eastern limb developed due to relative regional tilting to the east after deposition of the Claibornian Sparta Formation. The LaSalle arch acted as only a minor impediment to sediment transport with a very low relief except during the Tayloran Stage of the Upper Cretaceous. A single truncational unconformity in post-Triassic stratigraphy is present in the Taylora Demopolis Formation, indicating a period of relatively major uplift by the LaSalle arch. This contrast, with the Sabine arch in eastern Texas; the Sabine arch experienced uplift during the Eagle Fordian and Sabinian stages. A recently proposed hypothesis calling for overthrusting in the Western Cordillera as the mechanism for uplift on the Sabine arch cannot explain movement of the LaSalle arch because horizontal stress would predict synchronous uplift of basement highs. A more satisfactory uplift mechanism calls upon lateral heat flow from the mantle as the driving force for uplift.« less

Crustal uplift in the south central Alaska subduction zone: New analysis and interpretation of tide gauge observations

NASA Astrophysics Data System (ADS)

Cohen, Steven C.; Freymueller, Jeffrey T.

2001-06-01

We have examined tide gauge measurements of apparent sea level height in south central Alaska to determine the history of crustal uplift subsequent to the 1964 Prince William Sound earthquake. There are spatial and temporal variations in the uplift rate since the 1994 earthquake that depend on the location of the tide gauge relative to the coseismic rupture features. At Seward, on the eastern side of the Kenai Peninsula, we find slow uplift that is consistent with elastic strain accumulation at the locked North American-Pacific Plate boundary. Conversely, at Seldovia and Nikiski, on the western side of the Kenai Peninsula, we find persistent rapid uplift of ˜10 mm yr-1 that may be longterm transient response to the earthquake but that cannot be sustained over the entire several hundred year recurrence interval for a great earthquake. Farther to the southwest, at Kodiak, the rate of uplift is several millimeters per year but has slowed significantly over the past three and a half decades. To the east of the Kenai Peninsula we find subsidence at Cordova and an uncertain behavior at Valdez. At Cordova, and to a lesser extent Valdez, there is a mathematically significant time dependence, although the evidence for the time dependence is less compelling than at Kodiak. At Anchorage, there is little evidence of vertical motion since the earthquake. The along-strike spatial variability in the relaxation time of the rates of vertical motion since the 1964 earthquake may be related to variations in the updip coseismic slip during the megathrust event.

Evidence and biogeochemical implications for glacially-derived sediments in an active margin cold seep

USGS Publications Warehouse

Pohlman, John W.; Riedel, Michael; Novosel, Ivana; Bauer, James E.; Canuel, Elizabeth A.; Paull, Charles K.; Coffin, Richard B.; Grabowski, Kenneth S.; Knies, David L.; Hyndman, Roy D.; Spence, George D.

2011-01-01

Delineating sediment organic matter origins and sediment accumulation rates at gas hydratebearing and hydrocarbon seeps is complicated by the microbial transfer of 13C-depleted and 14Cdepleted methane carbon into sedimentary pools. Sediment 13C and 14C measurements from four cores recovered at Bullseye vent on the northern Cascadia margin are used to identify methane carbon assimilation into different carbon pools. While the total organic carbon (TOC) is mostly unaltered and primarily terrigenous in origin, planktonic foraminifera and the bulk carbonate display evidence of methane overprinting. Mass balance models are applied to determine the extent to which methane overprinting increased the radiocarbon ages of the biogenic foraminifera. The corrected and calibrated foraminifera ages between sediment depths of 70 and 573 cm are from 14.9 to 15.9 ka BP, which coincides with the retreat of the late Quaternary Cordilleran Ice Sheet from Vancouver Island. Uniform TOC _13C values of -24.5 ± 0.5‰ from the upper 8 meters of sediment at Bullseye vent suggest all cored material is Pleistocene-derived glacimarine material deposited as the ice edge retreated landward. Bullseye vent is located within an uplifted sediment block isolated from turbidite deposition and has been a site of non-deposition since the ice sheet retreated from the shelf. Biogeochemical implications of seep sediments being dominated by aged, organic-poor (<0.4 wt% TOC) material are that methane is the primary energy source, and microbes directly and indirectly associated with the anaerobic oxidation of methane (AOM) will dominate the seep microbial community.

Geomorphic Evidence of a Complex late-Cenozoic Uplift and Lateral Displacement History Along the 2013 M7.7 Baluchistan, Pakistan Strike-slip Rupture

NASA Astrophysics Data System (ADS)

Harbor, D. J.; Barnhart, W. D.

2017-12-01

The 2013 M7.7 Baluchistan earthquake in southern Pakistan ruptured 200 km of the north-dipping Hoshab reverse fault with dominantly lateral motion, clearly at odds with the regional topography created by previous reverse fault offsets. The kinematics of this earthquake led to the hypotheses that the Hoshab fault may alternatively slip in a reverse and lateral sense (bi-modal slip), and that the southeast Makran rotates as a uniform block around the fault (ball-and-socket rotation). Here, we use river profiles, regional relief, fault locations, and detailed geomorphic maps derived from optical imagery and DEMs to evaluate the recent uplift history of this region. We find that late Cenozoic fault zone geomorphology supports a spatially complex transition from lateral-dominated offsets in the NE to reverse-dominated offsets in the SW. Additionally, fault zone geomorphology suggests that the location of the Hoshab fault itself may change through time, leading to active incision of footwall alluvial fans and pediments. Stream profiles likewise record incision patterns that vary along the Hoshab fault. Incision and deposition in the SW are illustrative of relative footwall subsidence, consistent with recent uplift on the Hoshab fault; whereas incision and deposition in the NE are illustrative of relative footwall uplift consistent with ongoing regional uplift due to ball-and-socket rotations and dominantly lateral offsets along the northern Hoshab fault. The largest streams also record multiple, discrete, base-level drops, including the presence of convex-up river profiles in the hanging wall of the Hoshab fault. These profiles along hanging wall streams highlight a complex spatial and temporal history of reverse offset, lateral channel offset, and base-level resetting in regional streams that are altogether inconsistent with the kinematics of the 2013 earthquake alone, but that are consistent with the bi-modal slip model. Additionally, the evidence of footwall uplift in the NE is consistent with regional uplift due to ball-and-socket rotations superimposed on the Hoshab fault. These results indicate that the styles of fault slip in the Makran change in time and space in response to ongoing convergence and block rotations despite negligible uplift during the 2013 earthquake.

Depositional Architecture of Late Pleistocene-Holocene Coastal Alluvial-fan System in the Coastal Range, Taiwan

NASA Astrophysics Data System (ADS)

Chen, S. T.; Chen, W. S.

2016-12-01

Since late Pleistocene, the Coastal Range (Philippine Sea plate) collided and overridden on the Central Range (Eurasian Plate) along the Longitudinal Valley Fault. Therefore, the Coastal Range is exposed widely the late Pleistocene-Holocene marine and fluvial terraces caused by the tectonic uplift. Based on the estimation of paleosea-level elevations (Δh), depositional paleodepth, altitude distribution of Holocene deposits (D), altitude of outcrops (H), and 14C dating of marine deposits (t), the uplift rate (=(Δh+H +d-D)/t) is about 5-10 mm/yr in the southern Coastal Range. In this study, we suggest through field logging that the deposits can be divided into alluvial, foreshore (intertidal), shoreface, and offshore environments. In Dulan area in the southern Coastal Range, the uplift rate was 6-7 mm/yr during 16,380-10,000 cal yr BP and 3-4 mm/yr after 7,000 cal yr BP. Results from the Dulan Coastal alluvial-fan system can be divided into five depositional stages: (1) 16,380-14,300 cal yr BP: The rate of global sea level rise (SLR) has averaged about 6-7 mm/yr, similar to the tectonic uplift rate. In this stage, the bedrock was eroded and formed a wide wave-cut platform. (2) 14,300-10,000 cal yr BP: SLR of about 14 mm/yr that was faster than tectonic uplift rate of 6-7 mm/yr. As a result of transgression, the beach-lagoon deposits about 5 m thick were unconformably overlain on the wave-cut platform. (3) 10,000-8,200 cal yr BP: The ongoing sea level rise (SLR: 11 mm/yr), the lagoon deposits were overlain by an offshore slump deposits representing a gradual deepening of the depositional environment. (4) 8,200-7,930 cal yr BP (SLR: 6-7 mm/yr): The tectonic uplift rate may occur at similar SLR. The alluvial-fan deposits have prograded over the shallow marine deposits. (5) After 7,000 cal yr BP (SLR: 1-0 mm/yr): SLR was much slower than tectonic uplift rate of 3-4 mm/yr. Thus, Holocene marine terraces are extensively developed in the coastal region, showing that the Holocene marine deposits rest above the fluvial deposits. The crustal high uplift rates of relative sea-level changes led to form a well-developed multiple Holocene marine terraces.

Tectonic influences on the preservation of marine terraces: Old and new evidence from Santa Catalina Island, California

USGS Publications Warehouse

Schumann, R. Randall; Minor, Scott A.; Muhs, Daniel R.; Groves, Lindsey T.; McGeehin, John P.

2012-01-01

The California Channel Islands contain some of the best geologic records of past climate and sea-level changes, recorded in uplifted, fossil-bearing marine terrace deposits. Among the eight California Channel Islands and the nearby Palos Verdes Hills, only Santa Catalina Island does not exhibit prominent emergent marine terraces, though the same terrace-forming processes that acted on the other Channel Islands must also have occurred on Santa Catalina. We re-evaluated previous researchers' field evidence and examined new topographic, bathymetric, and stream-profile data in order to find possible explanations for the lack of obvious marine terrace landforms or deposits on the island today. The most likely explanation is associated with the island's unresolved tectonic history, with evidence for both recent uplift and subsidence being offered by different researchers. Bathymetric and seismic reflection data indicate the presence of submerged terrace-like landforms from a few meters below present sea level to depths far exceeding that of the lowest glacial lowstand, suggesting that the Catalina Island block may have subsided, submerging marine terraces that would have formed in the late Quaternary. Similar submerged marine terrace landforms exist offshore of all of the other California Channel Islands, including some at anomalously great depths, but late Quaternary uplift is well documented on those islands. Therefore, such submarine features must be more thoroughly investigated and adequately explained before they can be accepted as definitive evidence of subsidence. Nevertheless, the striking similarity of the terrace-like features around Santa Catalina Island to those surrounding the other, uplifting, Channel Islands prompted us to investigate other lines of evidence of tectonic activity, such as stream profile data. Recent uplift is suggested by disequilibrium stream profiles on the western side of the island, including nickpoints and profile convexities. Rapid uplift is also indicated by the island's highly dissected, steep topography and abundant landslides. A likely cause of uplift is a restraining bend in the offshore Catalina strike-slip fault. Our analysis suggests that Santa Catalina Island has recently experienced, and may still be experiencing, relatively rapid uplift, causing intense landscape rejuvenation that removed nearly all traces of marine terraces by erosion. A similar research approach, incorporating submarine as well as subaerial geomorphic data, could be applied to many tectonically active coastlines in which a marine terrace record appears to be missing.

Paleokarst on the top of the Maokou Formation: Further evidence for domal crustal uplift prior to the Emeishan flood volcanism

NASA Astrophysics Data System (ADS)

He, Bin; Xu, Yi-Gang; Guan, Jun-Peng; Zhong, Yu-Ting

2010-09-01

The ~ 260 Ma Emeishan Large Igneous Province (ELIP) in southwest China has previously been demonstrated to provide compelling evidence for pre-volcanic crustal doming in support of the mantle plume hypothesis. However this has been questioned by Ukstins-Peate and Bryan (2008) by showing hydrothermal magmatic activity at the Daqiao section. To solve this argument, a detailed characterization of the contact between the Emeishan basalts and the Maokou Formation was carried out. The contact is shown to be an unconformity, which is characterized by paleokarst on top of the Maokou Formation, including paleokarst relief, sinkholes, caves, tower karst and its corresponding rocks (such as kaolinite, bauxite and ferruginous duricrust and collapsed breccias, etc.). This paleokarst unconformity was in turn covered or infilled by the Emeishan basalts and tuffs, suggesting that uplift and erosion occurred prior to the eruption of the ELIP. The extent of erosion of the Maokou Formation indicates the ELIP can be divided into three roughly concentric zones: the inner, intermediate, and outer zones. The paleokarst features on the top of Maokou Formation vary across the ELIP. In the inner zone, a likely sinkhole and an incision valley with 450 m relief in height are found. In the intermediate zone, various paleokarst landforms such as karst relief, sinkholes and tower karsts are well developed. Some sinkholes that developed in the Qixia Formation below the Maokou Formation imply that the paleorelief is more than 350 m in height. In the outer zone, the paleokarstic surface is a paleo-weathering layer with minor karstification and development of caves at 10-50 m. This spatial variation of the paleokarst reflects variation of uplift height across the ELIP. The extent of minimal uplift is estimated to be at least 450 m in the inner zone, 350 m in the intermediate zone, whereas uplift is minor (tens-50 m) in the outer zone. The magnitude and shape of the uplift is roughly consistent with that predicted by mantle plume models. The paleokarst was formed after the deposition of the Maokou Formation and the eruption of the Emeishan basalts at the end-Guadalupian and indicates a short duration of uplift. Thus this study lends further support to domal uplift prior to the Emeishan flood volcanism, but also to the mantle plume initiation model for the generation of the ELIP.

Effects of the Laramide Structures on the Regional Distribution of Tight-Gas Sandstone in the Upper Mesaverde Group, Uinta Basin, Utah

NASA Astrophysics Data System (ADS)

Sitaula, R. P.; Aschoff, J.

2013-12-01

Regional-scale sequence stratigraphic correlation, well log analysis, syntectonic unconformity mapping, isopach maps, and depositional environment maps of the upper Mesaverde Group (UMG) in Uinta basin, Utah suggest higher accommodation in northeastern part (Natural Buttes area) and local development of lacustrine facies due to increased subsidence caused by uplift of San Rafael Swell (SRS) in southern and Uinta Uplift in northern parts. Recently discovered lacustrine facies in Natural Buttes area are completely different than the dominant fluvial facies in outcrops along Book Cliffs and could have implications for significant amount of tight-gas sand production from this area. Data used for sequence stratigraphic correlation, isopach maps and depositional environmental maps include > 100 well logs, 20 stratigraphic profiles, 35 sandstone thin sections and 10 outcrop-based gamma ray profiles. Seven 4th order depositional sequences (~0.5 my duration) are identified and correlated within UMG. Correlation was constructed using a combination of fluvial facies and stacking patterns in outcrops, chert-pebble conglomerates and tidally influenced strata. These surfaces were extrapolated into subsurface by matching GR profiles. GR well logs and core log of Natural Buttes area show intervals of coarsening upward patterns suggesting possible lacustrine intervals that might contain high TOC. Locally, younger sequences are completely truncated across SRS whereas older sequences are truncated and thinned toward SRS. The cycles of truncation and thinning represent phases of SRS uplift. Thinning possibly related with the Uinta Uplift is also observed in northwestern part. Paleocurrents are consistent with interpretation of periodic segmentation and deflection of sedimentation. Regional paleocurrents are generally E-NE-directed in Sequences 1-4, and N-directed in Sequences 5-7. From isopach maps and paleocurrent direction it can be interpreted that uplift of SRS changed route of sediment supply from west to southwest. Locally, paleocurrents are highly variable near SRS further suggesting UMG basin-fill was partitioned by uplift of SRS. Sandstone composition analysis also suggests the uplift of SRS causing the variation of source rocks in upper sequences than the lower sequences. In conclusion, we suggest that Uinta basin was episodically partitioned during the deposition of UMG due to uplift of Laramide structures in the basin and accommodation was localized in northeastern part. Understanding of structural controls on accommodation, sedimentation patterns and depositional environments will aid prediction of the best-producing gas reservoirs.

Uplifting of the Jiamusi Block in the eastern Central Asian Orogenic Belt, NE China: evidence from basin provenance and geochronology

NASA Astrophysics Data System (ADS)

Liu, Yongjiang; Wen, Quanbo; Han, Guoqing; Li, Wei

2010-05-01

The main part of Jiamusi Block, named as Huanan-Uplift, is located in the northeastern Heilongjiang, China. The Huanan-Uplift is surrounded by many relatively small Mesozoic-Cenozoic basins, e.g. Sanjiang Basin, Hulin Basin, Boli Basin, Jixi Basin, Shuangyashan Basin and Shuanghua Basin. However previous research works were mainly focused on stratigraphy and palaeontology of the basins, therefore, the coupling relation between the uplift and the surrounding basins have not been clear. Based on the field investigations, conglomerate provenance studies of the Houshigou Formation in Boli Basin, geochronology of the Huanan-Uplift basement, we have been studied the relationships between Huanan-Uplift and the surrounding basins. The regional stratigraphic correlations indicates that the isolated basins in the area experienced the same evolution during the period of the Chengzihe and the Muling Formations (the Early Cretaceous). The paleogeography reconstructions suggest that the area had been a large-scale basin as a whole during the Early Cretaceous. The Huanan-Uplift did not exist. The paleocurrent directions, sandstone and conglomerate provenance analyses show that the Huanan-Uplift started to be the source area of the surrounding basins during the period of Houshigou Formation (early Late Cretaceous), therefore, it suggests that the Jiamusi Block commenced uplift in the early Late Cretaceous. The granitic gneisses in Huanan-Uplift give 494-415 Ma monazite U-Th-total Pb ages, 262-259 Ma biotite and 246-241 Ma K-feldspar 40Ar/39Ar ages. The cooling rates of 1-2 ℃/Ma from 500-260 Ma and 10-11 ℃/Ma from 260-240 Ma have been calculated based on the ages. This suggests that the Jiamusi Block had a rapid exhumation during late Permian, which should be related to the closure of the Paleo-Asian Ocean between the Siberian and North China continents. It is concluded that during the late Paleozoic the Jiamusi Block was stable with a very slow uplifting. With the closure of the Paleo-Asian Ocean the Jiamusi Block underwent a very rapid exhumation in the late Permian. In the early Mesozoic the area went into a basin developing stage and formed a large basin as a whole during the Early Cretaceous. In the Late Cretaceous the Jiamusi Block started uplifting and the basin was broken into isolate small basins. References: Bureau of Geology and Mineral Resources of Heilongjiang Province. Regional geology of Heilongjiang Province. Beijing: Geological Publishing House, 1993.578-581. Cao Chengrun, Zheng Qingdao. Structural evolution feature and its significance of hydrocarbon exploration in relict basin formation, Eastern Heilongjiang province. Journal of Jilin university (Earth Science Edition), 2003, 33(2):167-172. Lang Xiansheng. Biologic Assemblage features of Coal-bearing Strata in Shuangyashan-Jixian coal-field. Coal geology of China, 2002, 14(2):7-12. Piao Taiyuan , Cai Huawei , Jiang Baoyu. On the Cretaceous coal-bearing Strata in Eastern Heilongjiang. Journal Of Stratigraphy, 2005, 29:489-496. Wang Jie , He Zhonghua , Liu Zhaojun , Du Jiangfeng , Wang Weitao. Geochemical characteristics of Cretaceous detrital rocks and their constraint on provenance in Jixi Basin. Global Geology，2006, 25(4):341-348. DickinsonW R and Christopher A. Suczek. Plate Tectonics and Sandstone Composition. AAPG B. 1979,63(12 ):2164-2182. DickinsonW R, Beard L S, Brakenridge G R, et al. Provenance of North American Phanerozoic sandstones in relation to tectonic setting. Bull Geo-Soc Amer, 1983, 94: 222-235. Maruyama S, Seno T. Orogeny and relative plate motions: Example of the Japanese Islands. Tectonophysics, 1986，127(3-4):305-329. Maruyama S, Isozaki Y, Kimura Gand Terabayashi M C.Paleogeographic maps of the Japanese Islands: plate tectonic systhesis from 750 Ma to the present. Island Arc, 1997,6:121-142.

Changes in vegetation, peat properties and peat accumulation in Swedish peatlands as revealed by archive data.

NASA Astrophysics Data System (ADS)

Schoning, Kristian; Sohlenius, Gustav

2016-04-01

In this investigation we have studied patterns in peat accumulation and changes in mire status since the early 1900s for two areas in Sweden. In the early 1900s the Geological Survey of Sweden collected a vast amount of peat and peatland data, including information on vegetation and land-use. We have used this archive data to evaluate changes in mire vegetation, mire wetness and surface peat properties, rates of peat accumulation, succession in young wetlands and the effects of cultivation on peatlands. In total 156 mires in an uplift area of eastern middle Sweden were included in the data-set, including both pristine mires and peatlands used for agricultural purposes. In this area new peatlands have continuously been formed during the past 7 000 years making it possible to evaluate changes in peat accumulation over time. The other study area is situated in the south Swedish Uplands where we have revisited some larger bogs. The results from our investigation show that many of the peatlands have underwent major changes since the early 1900s. In most of the small peatlands we have found important changes in vegetation where mire vegetation has been replaced by nutrient demanding and/or dry species flora while the tree stand on large mires in south Sweden have increased. In some mires humification has increased in the uppermost peat-layers and the mire surface have become drier compared to the early 1900s. In eastern middle Sweden there are indications that the peat accumulation is lower 0,5 mm/year in older peatlands compared with younger ones 1,2 mm/year, although the mire vegetation in the older peatlands is dominated by sphagnum. The peat depth of the cultivated mires in this area shows a mean decrease of 40 cm since the early 1900s.