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Sample records for alter alpine lake

  1. Is atmospheric phosphorus pollution altering global alpine Lake stoichiometry?

    NASA Astrophysics Data System (ADS)

    Brahney, Janice; Mahowald, Natalie; Ward, Daniel S.; Ballantyne, Ashley P.; Neff, Jason C.

    2015-09-01

    Anthropogenic activities have significantly altered atmospheric chemistry and changed the global mobility of key macronutrients. Here we show that contemporary global patterns in nitrogen (N) and phosphorus (P) emissions drive large hemispheric variation in precipitation chemistry. These global patterns of nutrient emission and deposition (N:P) are in turn closely reflected in the water chemistry of naturally oligotrophic lakes (r2 = 0.81, p < 0.0001). Observed increases in anthropogenic N deposition play a role in nutrient concentrations (r2 = 0.20, p < 0.05) however, atmospheric deposition of P appears to be major contributor to this pattern (r2 = 0.65, p < 0.0001). Atmospheric simulations indicate a global increase in P deposition by 1.4 times the preindustrial rate largely due to increased dust and biomass burning emissions. Although changes in the mass flux of global P deposition are smaller than for N, the impacts on primary productivity may be greater because, on average, one unit of increased P deposition has 16 times the influence of one unit of N deposition. These stoichiometric considerations, combined with the evidence presented here, suggest that increases in P deposition may be a major driver of alpine Lake trophic status, particularly in the Southern Hemisphere. These results underscore the need for the broader scientific community to consider the impact of atmospheric phosphorus deposition on the water quality of naturally oligotrophic lakes.

  2. Dust mediated transfer of phosphorus to alpine lake ecosystems

    NASA Astrophysics Data System (ADS)

    Brahney, J.; Ballantyne, A. P.; Kociolek, P.; Neff, J. C.

    2013-05-01

    Alpine lakes receive a large fraction of their nutrients from atmospheric sources; thus they are potentially sensitive to variations in atmospheric dust loading. Dust generation in western USA is thought to be increasing due to climate and land-use practices; however, the dust-mediated transfer of nutrients to alpine lakes and the potential for ecological consequences has not been extensively investigated in this region. Here, we explore the spatial changes in lake water chemistry and biology across a gradient of dust deposition in the Wind River Range, Wyoming, USA. Areas that receive more dust have altered lake and sediment water chemistries as well as altered planktonic communities. In particular, we found that phosphorus concentrations and primary productivity in dust-impacted alpine lakes were significantly greater than non-dust impacted lakes. The data illustrate the degree to which dust deposition may influence lake water chemistry and planktonic species composition, and the potential influence of human activities on remote alpine ecosystems.

  3. The potential for retreating alpine glaciers to alter alpine ecosystems in the Colorado Front Range

    NASA Astrophysics Data System (ADS)

    Hall, E.; Baron, J.

    2013-12-01

    Glaciers are retreating at an unprecedented rate. In mid-latitude alpine ecosystems the presence of glaciers and rock glaciers govern rates and ecology of alpine and sub-alpine ecosystems. Changes in the thermal environment due to the loss of isothermal habitat and inputs from glacier melt chemistry are altering alpine ecosystems in unpredictable ways. In particular, glacier may be a source of nitrogen that is altering alpine ecosystem dynamics. Loch Vale Watershed (LVWS) located within Rocky Mountain National Park. LVWS contains a surface glacier (Andrew's glacier) and a rock glacier (Taylor's glacier) at the headwater of each of the two drainages within the watershed. We collected precipitation from a National Atmospheric Deposition Site and surface water from multiple alpine lakes and streams during a particularly high and low snow year in the Colorado Front Range. We also sampled stream and lake sediments at each site to analyze the associated microbial community. Concentrations of nitrate and ammonium, relative abundance of amoA (the gene responsible for a key step in the microbial nitrification pathway), and the dual isotope signal to nitrate all point to snow melt as a key deliverer of nitrogen to ecosystems along the Colorado Front Range. However, late summer surface water chemistry is isotopically similar to the chemistry of glacial ice. This suggests that retreating glacier may be an additional source of N to alpine ecosystems and have the potential to alter microbial community composition, biogeochemical rate processes, and ecosystem function. These dynamics are most likely not unique to the Colorado Front Range and should be globally distributed as glaciers continue to retreat in high altitude ecosystems around the world.

  4. ALPINE LAKES WILDERNESS STUDY AREA, WASHINGTON.

    USGS Publications Warehouse

    Gualtieri, J.L.; Thurber, H.K.

    1984-01-01

    The Alpine Lakes Wilderness study area, located in the central part of the Cascade Mountains of Washington was examined for its mineral-resource potential. On the basis of that study the area was found to contain deposits of copper, other base metals, and gold and silver. Probable or substantiated mineral-resource potential exists for these commodities in the southwest-central, northwest, and southeast-central parts of the area. The geologic terrane precludes the occurrence of fossil fuel resources.

  5. Agriculture causes nitrate fertilization of remote alpine lakes

    NASA Astrophysics Data System (ADS)

    Hundey, E. J.; Russell, S. D.; Longstaffe, F. J.; Moser, K. A.

    2016-02-01

    Humans have altered Earth's nitrogen cycle so dramatically that reactive nitrogen (Nr) has doubled. This has increased Nr in aquatic ecosystems, which can lead to reduced water quality and ecosystem health. Apportioning sources of Nr to specific ecosystems, however, continues to be challenging, despite this knowledge being critical for mitigation and protection of water resources. Here we use Δ17O, δ18O and δ15N from Uinta Mountain (Utah, USA) snow, inflow and lake nitrate in combination with a Bayesian-based stable isotope mixing model, to show that at least 70% of nitrates in aquatic systems are anthropogenic and arrive via the atmosphere. Moreover, agricultural activities, specifically nitrate- and ammonium-based fertilizer use, are contributing most (~60%) Nr, and data from other North American alpine lakes suggest this is a widespread phenomenon. Our findings offer a pathway towards more effective mitigation, but point to challenges in balancing food production with protection of important water resources.

  6. Agriculture causes nitrate fertilization of remote alpine lakes.

    PubMed

    Hundey, E J; Russell, S D; Longstaffe, F J; Moser, K A

    2016-01-01

    Humans have altered Earth's nitrogen cycle so dramatically that reactive nitrogen (Nr) has doubled. This has increased Nr in aquatic ecosystems, which can lead to reduced water quality and ecosystem health. Apportioning sources of Nr to specific ecosystems, however, continues to be challenging, despite this knowledge being critical for mitigation and protection of water resources. Here we use Δ(17)O, δ(18)O and δ(15)N from Uinta Mountain (Utah, USA) snow, inflow and lake nitrate in combination with a Bayesian-based stable isotope mixing model, to show that at least 70% of nitrates in aquatic systems are anthropogenic and arrive via the atmosphere. Moreover, agricultural activities, specifically nitrate- and ammonium-based fertilizer use, are contributing most (∼60%) Nr, and data from other North American alpine lakes suggest this is a widespread phenomenon. Our findings offer a pathway towards more effective mitigation, but point to challenges in balancing food production with protection of important water resources. PMID:26853267

  7. Agriculture causes nitrate fertilization of remote alpine lakes

    PubMed Central

    Hundey, E. J.; Russell, S. D.; Longstaffe, F. J.; Moser, K. A.

    2016-01-01

    Humans have altered Earth's nitrogen cycle so dramatically that reactive nitrogen (Nr) has doubled. This has increased Nr in aquatic ecosystems, which can lead to reduced water quality and ecosystem health. Apportioning sources of Nr to specific ecosystems, however, continues to be challenging, despite this knowledge being critical for mitigation and protection of water resources. Here we use Δ17O, δ18O and δ15N from Uinta Mountain (Utah, USA) snow, inflow and lake nitrate in combination with a Bayesian-based stable isotope mixing model, to show that at least 70% of nitrates in aquatic systems are anthropogenic and arrive via the atmosphere. Moreover, agricultural activities, specifically nitrate- and ammonium-based fertilizer use, are contributing most (∼60%) Nr, and data from other North American alpine lakes suggest this is a widespread phenomenon. Our findings offer a pathway towards more effective mitigation, but point to challenges in balancing food production with protection of important water resources. PMID:26853267

  8. The use of invertebrates as indicators of environmental change in alpine rivers and lakes.

    PubMed

    Khamis, K; Hannah, D M; Brown, L E; Tiberti, R; Milner, A M

    2014-09-15

    In alpine regions climatic change will alter the balance between water sources (rainfall, ice-melt, snowmelt, and groundwater) for aquatic systems, particularly modifying the relative contributions of meltwater, groundwater and rain to both rivers and lakes. While these changes are expected to have implications for alpine aquatic ecosystems, little is known about potential ecological tipping points and associated indicator taxa. We examined changes in biotic communities along a gradient of glacier influence for two study systems: (1) a stream network in the French Pyrénées; and (2) a network of lakes in the Italian Alps, with the aim of identifying potential indicator taxa (macroinvertebrates and zooplankton) of glacier retreat in these environments. To assess parallels in biotic responses across streams and lakes, both primary data and findings from other publications were synthesised. Using TITAN (Threshold Indicator Taxa ANalysis) changes in community composition of river taxa were identified at thresholds of <5.1% glacier cover and <66.6% meltwater contribution. Below these thresholds the loss of cold stenothermic benthic invertebrate taxa, Diamesa spp. and the Pyrenean endemic Rhyacophila angelieri was apparent. Some generalist taxa including Protonemura sp., Perla grandis, Baetis alpinus, Rhithrogena loyolaea and Microspectra sp. increased when glacier cover was <2.7% and <52% meltwater. Patterns were not as distinct for the alpine lakes, due to fewer sampling sites; however, Daphnia longispina grp. and the benthic invertebrate groups Plectopera and Planaria were identified as potential indicator taxa. While further work is required to assess potential indicator taxa for alpine lake systems, findings from alpine river systems were consistent between methods for assessing glacier influence (meltwater contribution/glacier cover). Hence, it is clear that TITAN could become a useful management tool, enabling: (i) the identification of taxa particularly

  9. Estimating the volume of Alpine glacial lakes

    NASA Astrophysics Data System (ADS)

    Cook, S. J.; Quincey, D. J.

    2015-09-01

    Supraglacial, moraine-dammed and ice-dammed lakes represent a potential glacial lake outburst flood (GLOF) threat to downstream communities in many mountain regions. This has motivated the development of empirical relationships to predict lake volume given a measurement of lake surface area obtained from satellite imagery. Such relationships are based on the notion that lake depth, area and volume scale predictably. We critically evaluate the performance of these existing empirical relationships by examining a global database of measured glacial lake depths, areas and volumes. Results show that lake area and depth are not always well correlated (r2 = 0.38), and that although lake volume and area are well correlated (r2 = 0.91), there are distinct outliers in the dataset. These outliers represent situations where it may not be appropriate to apply existing empirical relationships to predict lake volume, and include growing supraglacial lakes, glaciers that recede into basins with complex overdeepened morphologies or that have been deepened by intense erosion, and lakes formed where glaciers advance across and block a main trunk valley. We use the compiled dataset to develop a conceptual model of how the volumes of supraglacial ponds and lakes, moraine-dammed lakes and ice-dammed lakes should be expected to evolve with increasing area. Although a large amount of bathymetric data exist for moraine-dammed and ice-dammed lakes, we suggest that further measurements of growing supraglacial ponds and lakes are needed to better understand their development.

  10. Estimating the volume of Alpine glacial lakes

    NASA Astrophysics Data System (ADS)

    Cook, S. J.; Quincey, D. J.

    2015-12-01

    Supraglacial, moraine-dammed and ice-dammed lakes represent a potential glacial lake outburst flood (GLOF) threat to downstream communities in many mountain regions. This has motivated the development of empirical relationships to predict lake volume given a measurement of lake surface area obtained from satellite imagery. Such relationships are based on the notion that lake depth, area and volume scale predictably. We critically evaluate the performance of these existing empirical relationships by examining a global database of glacial lake depths, areas and volumes. Results show that lake area and depth are not always well correlated (r2 = 0.38) and that although lake volume and area are well correlated (r2 = 0.91), and indeed are auto-correlated, there are distinct outliers in the data set. These outliers represent situations where it may not be appropriate to apply existing empirical relationships to predict lake volume and include growing supraglacial lakes, glaciers that recede into basins with complex overdeepened morphologies or that have been deepened by intense erosion and lakes formed where glaciers advance across and block a main trunk valley. We use the compiled data set to develop a conceptual model of how the volumes of supraglacial ponds and lakes, moraine-dammed lakes and ice-dammed lakes should be expected to evolve with increasing area. Although a large amount of bathymetric data exist for moraine-dammed and ice-dammed lakes, we suggest that further measurements of growing supraglacial ponds and lakes are needed to better understand their development.

  11. Differences in UV transparency and thermal structure between alpine and subalpine lakes: implications for organisms†

    PubMed Central

    Rose, Kevin C.; Williamson, Craig E.; Saros, Jasmine E.; Sommaruga, Ruben; Fischer, Janet M.

    2010-01-01

    Ultraviolet (UV) radiation is a globally important abiotic factor influencing ecosystem structure and function in multiple ways. While UV radiation can be damaging to most organisms, several factors act to reduce UV exposure of organisms in aquatic ecosystems, the most important of which is dissolved organic carbon (DOC). In alpine lakes, very low concentrations of DOC and a thinner atmosphere lead to unusually high UV exposure levels. These high UV levels combine with low temperatures to provide a fundamentally different vertical structure to alpine lake ecosystems in comparison to most lowland lakes. Here, we discuss the importance of water temperature and UV transparency in structuring alpine lake ecosystems and the consequences for aquatic organisms that inhabit them. We present transparency data on a global data set of alpine lakes and nearby analogous subalpine lakes for comparison. We also present seasonal transparency data on a suite of alpine and subalpine lakes that demonstrate important differences in UV and photosynthetically active radiation (PAR, 400–700 nm) transparency patterns even within a single region. These data are used to explore factors regulating transparency in alpine lakes, to discuss implications of future environmental change on the structure and function of alpine lakes, and ways in which the UV transparency of these lakes can be used as a sentinel of environmental change. PMID:19707613

  12. Catchment nitrogen saturation drives ecological change in an alpine lake in SW China (eastern margin of Tibet)

    NASA Astrophysics Data System (ADS)

    Anderson, N. J.; Hu, Z.; Yang, X.; Zhang, E.

    2011-12-01

    There is substantial evidence for recent (last ca. 120 years) ecological change in remote arctic and alpine lakes (increased productivity, altered biological structure). Initially, these changes were attributed to global warming which has altered the heat budgets of these lakes (stronger stratification, longer ice free periods). The emphasis on temperature, however, ignores that global environmental change is driven by a range of multiple stressors (e.g. altered biogeochemical cycles, land cover change). One of the characteristics of the observed change in remote lakes is the expansion of small species of the planktonic diatom genus Cyclotella. It is increasingly obvious that the recent success of this diatom genus is driven by other factors (nutrients, light, mixing depth) as much as temperature. SE Asia is a major hotspot for the emission of reactive nitrogen as a result of intensive agriculture and fossil fuel combustion. In this study we report recent ecological change in a small, oligotrophic alpine lake (ShadeCo; altitude 4423 m) located in Sichuan Province (SW China), one of many relatively unstudied alpine lakes on the eastern margin of Tibet. The lake is located above the tree-line and there is no cultural land-use; the catchment vegetation is dominated by alpine shrub (predominantly Rhododendron). We used a multi-proxy palaeolimnological approach (diatom, geochemical and stable isotope analyses of a 210-Pb dated core) coupled with regional long-term climate data to understand the pronounced 20th century changes in the diatom record, notably an expansion of Cyclotella spp from around 1920. This initial increase is coincident with warming in SW China but the maximum Cyclotella abundance occurs in in the 1970s and 1980s, a period of regional cooling and major changes in catchment-lake biogeochemistry as indicated by geochemical analyses. The possible drivers of the observed changes (nitrogen deposition, temperature) at this site are discussed in the context

  13. Small lakes in big landscape: Multi-scale drivers of littoral ecosystem in alpine lakes.

    PubMed

    Zaharescu, Dragos G; Burghelea, Carmen I; Hooda, Peter S; Lester, Richard N; Palanca-Soler, Antonio

    2016-05-01

    In low nutrient alpine lakes, the littoral zone is the most productive part of the ecosystem, and it is a biodiversity hotspot. It is not entirely clear how the scale and physical heterogeneity of surrounding catchment, its ecological composition, and larger landscape gradients work together to sustain littoral communities. A total of 113 alpine lakes from the central Pyrenees were surveyed to evaluate the functional connectivity between littoral zoobenthos and landscape physical and ecological elements at geographical, catchment and local scales, and to ascertain how they affect the formation of littoral communities. At each lake, the zoobenthic composition was assessed together with geolocation, catchment hydrodynamics, geomorphology and topography, riparian vegetation composition, the presence of trout and frogs, water pH and conductivity. Multidimensional fuzzy set models integrating benthic biota and environmental variables revealed that at geographical scale, longitude unexpectedly surpassed altitude and latitude in its effect on littoral ecosystem. This reflects a sharp transition between Atlantic and Mediterranean climates and suggests a potentially high horizontal vulnerability to climate change. Topography (controlling catchment type, snow coverage and lakes connectivity) was the most influential catchment-scale driver, followed by hydrodynamics (waterbody size, type and volume of inflow/outflow). Locally, riparian plant composition significantly related to littoral community structure, richness and diversity. These variables, directly and indirectly, create habitats for aquatic and terrestrial stages of invertebrates, and control nutrient and water cycles. Three benthic associations characterised distinct lakes. Vertebrate predation, water conductivity and pH had no major influence on littoral taxa. This work provides exhaustive information from relatively pristine sites, and unveils a strong connection between littoral ecosystem and catchment

  14. Evidence for local ciliate endemism in an alpine anoxic lake.

    PubMed

    Stoeck, Thorsten; Bruemmer, Franz; Foissner, Wilhelm

    2007-10-01

    Despite its long history, biogeography has received relatively little attention within the field of microbial ecology. Consequently, a fierce debate rages whether protists inhabit restricted geographic areas (endemism hypothesis) or are globally dispersed (ubiquitous dispersal hypothesis). The data presented in this article support the endemism hypothesis. We succeeded in isolating an oligohymenophorean ciliate from a microbial mat in a meromictic anoxic alpine lake (Alatsee) in Germany. The ciliary pattern and the morphometry of this isolate are remarkably similar to Urocentrum turbo (Mueller, 1786) Nitzsch, 1827. However, the organism does not possess trichocysts, a conspicuous and characteristic feature of U. turbo. Instead, the U. turbo-like isolate from lake Alatsee displays merely trichocyst anlagen ("ghosts") in the cytoplasm that are only visible after protargol impregnation and which become never attached to the cell's cortex. Despite the distinctness of this difference, such a morphospecies has not been described from any other environment. Thus, we suggest that the U. turbo-like isolate from lake Alatsee is a local endemic ecotype, although the sequences of the 18S rRNA, ITS1, 5.8S rRNA, and ITS2 genes are nearly identical to those of U. turbo (Mueller, 1786) Nitzsch, 1827. This indicates that neither 18S rDNA nor ITS1, ITS2, and 5.8S rDNA sequences are reliable means to conclusively resolve different morphospecies or ecotypes of ciliates. As a consequence, we argue that protist species richness can only be reliably accounted for by considering both molecular and morphological data. PMID:17323118

  15. Alpine Channel and Floodplain Dynamics in the Lake Tahoe Region, California

    NASA Astrophysics Data System (ADS)

    Liquori, M.; Chris, B.; Parris, A.; Heins, A.; Stofleth, J.; Wickland, M.

    2006-12-01

    Alpine floodplains provide diverse habitat components for terrestrial and aquatic species, and strongly influence bank stability and channel migration processes. They also present complex restoration challenges. Several systems in the Lake Tahoe region have been diagnosed with incised channel conditions that generate excessive mobile sediment from eroding banks, degrade riparian vegetation communities, and diminish floodplain wetland abundance and quality. Conventional efforts to restore these systems focus on reconnecting floodplains, primarily through channel or floodplain modifications designed to reestablish floodplain inundation frequency near a Q1.5 level. Recent observations along lower Squaw Creek and the Upper Truckee River suggest that human impacts and climate-induced shifts over the 20th Century appear to significantly change the processes and dynamics between channels and floodplains. Our observations highlight differences in alpine settings as compared with lowland environments. Increased rain-on-snow frequency appears to increase the importance of avulsion and channel widening processes over channel meander processes. Loss of channel sinuosity, increases in depth and changes in channel shape appear to follow rain-on-snow events. These changes affect the overall sediment transport regime, even as snowmelt duration continues to exert the primary influence over dominant discharge relationships. During floods, discontinuous, proximal deposition of coarse sediment replaces uniform, distal deposition of finer sediments, altering the structure of the channel bed and floodplain. Early snowmelt from developed hillslopes saturates floodplains even in the absence of regular flooding, potentially negating or eliminating the restorative benefit of increased flood frequency. These results suggest that effective long-term restoration strategies cannot rely on historic sinuosity patterns or simple flood frequency metrics, but must begin to understand how changes in

  16. Catchment-mediated atmospheric nitrogen deposition drives ecological change in two alpine lakes in SE Tibet.

    PubMed

    Hu, Zhujun; Anderson, Nicholas John; Yang, Xiangdong; McGowan, Suzanne

    2014-05-01

    The south-east margin of Tibet is highly sensitive to global environmental change pressures, in particular, high contemporary reactive nitrogen (Nr) deposition rates (ca. 40 kg ha(-1)  yr(-1) ), but the extent and timescale of recent ecological change is not well prescribed. Multiproxy analyses (diatoms, pigments and geochemistry) of (210) Pb-dated sediment cores from two alpine lakes in Sichuan were used to assess whether they have undergone ecological change comparable to those in Europe and North America over the last two centuries. The study lakes have contrasting catchment-to-lake ratios and vegetation cover: Shade Co has a relatively larger catchment and denser alpine shrub than Moon Lake. Both lakes exhibited unambiguous increasing production since the late 19th to early 20th. Principle component analysis was used to summarize the trends of diatom and pigment data after the little ice age (LIA). There was strong linear change in biological proxies at both lakes, which were not consistent with regional temperature, suggesting that climate is not the primary driver of ecological change. The multiproxy analysis indicated an indirect ecological response to Nr deposition at Shade Co mediated through catchment processes since ca. 1930, while ecological change at Moon Lake started earlier (ca. 1880) and was more directly related to Nr deposition (depleted δ(15) N). The only pronounced climate effect was evidenced by changes during the LIA when photoautotrophic groups shifted dramatically at Shade Co (a 4-fold increase in lutein concentration) and planktonic diatom abundance declined at both sites because of longer ice cover. The substantial increases in aquatic production over the last ca. 100 years required a substantial nutrient subsidy and the geochemical data point to a major role for Nr deposition although dust cannot be excluded. The study also highlights the importance of lake and catchment morphology for determining the response of alpine lakes to

  17. Soil development as trigger for lake productivity in a high alpine ecosystem

    NASA Astrophysics Data System (ADS)

    Koinig, Karin A.; Drescher, Ruth; Hirt, Ann; Ilyashuk, Elena; Lami, Andrea; Tessadri, Richard; Psenner, Roland

    2010-05-01

    In high alpine catchments, soil development significantly affects the lake's biogeochemistry and productivity. Here we present a Holocene multi-proxy sediment record of an oligothrophic high alpine lake. The multi-proxy analyses include geochemistry, mineralogy, magnetic properties, pollen, diatoms, chironomids, and pigment records. The sediment cores cover the entire lake history from the last deglaciation to present. The lake is located at 2800 m a.s.l., far above the potential tree line. Currently the catchment consists of bare rocks and scree and discontinuous small patches of thin soil. Alpine herbs and cushion plants account for the major part of the vegetation. After deglaciation, during a warm and presumably dry climate, the lake was rapidly colonized as seen from the diatom and chironomid record. However, it took over 2000 years (until 8000 cal BP) until the lake became more productive as reflected in an increase in organic carbon content and algae and chironomid concentrations. During this period the climate was still warm but wetter. The increase in productivity is consistent with a shift from a plankton dominated C/N ratio (between 9 and 12) to a higher C/N ratio that reflects a higher input of organic matter from terrestrial plants. This increase also triggered the development of anoxic - alkaline bottom water conditions and thus affected the whole biogeochemistry of the lake. With the onset of a colder period around 4500 cal BP, the C/N ratio decreased again and the lake became less productive. Although the catchment had only a scarce and thin soil layer, the development of a slightly more productive soil layer during favorable climatic conditions had significant effects on the lake properties.

  18. Satellite monitoring of dramatic changes at Hawai'i's only alpine lake: Lake Waiau on Mauna Kea volcano

    USGS Publications Warehouse

    Patrick, Matthew R.; Kauahikaua, James P.

    2015-01-01

    Lake Waiau is a small, typically 100-meter-long lake, located near the summit of Mauna Kea volcano, on the Island of Hawaiʻi. It is Hawaiʻi’s only alpine lake and is considered sacred in Hawaiian cultural tradition. Over the past few years, the lake has diminished in size, and, by October 2013, surface water had almost completely disappeared from the lake. In this study, we use high-resolution satellite images and aerial photographs to document recent changes at the lake. Based on our reconstructions covering the past 200 years, the historical lake surface area has typically ranged from 5,000 to 7,000 square meters, but in 2010 a dramatic plunge in lake area ensued. The lake area rebounded significantly in early 2014, following heavy winter storms. This near disappearance of the lake, judging from analysis of visitor photographs and field reports, appears to be highly unusual, if not unprecedented, in the historical record. The unusually low water levels in the lake are consistent with a recent severe drought in Hawaiʻi.

  19. Scalable Climate Forcing Optical Indices: How Effective Are They in Alpine Lakes?

    NASA Astrophysics Data System (ADS)

    Williamson, C. E.; Overholt, E.; Fischer, J.; Olson, M.; Brentrup, J.; Saros, J. E.; Melack, J. M.

    2014-12-01

    As the world gets warmer and wetter, it is important to identify sentinel systems to resolve the response of ecosystems to climate change across drivers and complex landscapes. Recently developed climate forcing optical indices (CFOI) related to the quality and quantity of dissolved organic carbon (DOC) have been shown to be scalable from short-term storm events to interdecadal periods in diverse lakes in lowland landscapes. Are these CFOI metrics effective in alpine ecosystems, which are often viewed as more responsive sentinels of climate change than lowland ecosystems? DOC-related optical data from a series of alpine lakes in North America are used here to address this question. The response of these CFOI metrics followed the same tight relationship in alpine lakes as in lowland lakes, with a seasonal increase in spectral slope between 275 and 295 nm (S275-295) and a decrease in DOC-specific absorbance at 320 nm (a*320) as well as in the ratio of these two indices (a*320/S275-295, a composite climate forcing index, CF). These changes are likely driven largely by photobleaching of terrestrial DOC during the ice-free season. Closer analysis of five years of data for Lake Oesa in the Canadian Rockies revealed marginally significant relationships between precipitation and the CFOI metrics. Specifically, S275-295 decreased with increasing cumulative precipitation for the 15 day period preceding water sample collection. a*320 increased with cumulative precipitation for the 45 day period preceding water sample collection. Relationships between CFOI metrics and precipitation at other time scales were not significant. While the DOC-quality related CFOI metrics were responsive to precipitation, DOC concentration alone was not. The time scale of precipitation effects on CFOI metrics in Lake Oesa was shorter than those previously observed for lowland lakes. This contrasting response is likely related to differences in the characteristics of the hydrology and catchments of

  20. UV-induced DNA damage in Cyclops abyssorum tatricus populations from clear and turbid alpine lakes

    PubMed Central

    Tartarotti, Barbara; Saul, Nadine; Chakrabarti, Shumon; Trattner, Florian; Steinberg, Christian E. W.; Sommaruga, Ruben

    2014-01-01

    Zooplankton from clear alpine lakes thrive under high levels of solar UV radiation (UVR), but in glacially turbid ones they are more protected from this damaging radiation. Here, we present results from experiments done with Cyclops abyssorum tatricus to assess UV-induced DNA damage and repair processes using the comet assay. Copepods were collected from three alpine lakes of differing UV transparency ranging from clear to glacially turbid, and exposed to artificial UVR. In addition, photoprotection levels [mycosporine-like amino acids (MAAs) and lipophilic antioxidant capacity] were estimated in the test populations. Similar UV-induced DNA damage levels were observed among the copepods from all lakes, but background DNA damage (time zero and dark controls) was lowest in the copepods from the glacially turbid lake, resulting in a higher relative DNA damage accumulation. Most DNA strand breaks were repaired after recovery in the dark. Low MAA concentrations were found in the copepods from the glacially turbid lake, while the highest levels were observed in the population from the most UV transparent lake. However, the highest lipophilic antioxidant capacities were measured in the copepods from the lake with intermediate UV transparency. Photoprotection and the ability to repair DNA damage, and consequently reducing UV-induced damage, are part of the response mechanisms in zooplankton to changes in water transparency caused by glacier retreat. PMID:24616551

  1. Photochemical reactivities of dissolved organic matter (DOM) in a sub-alpine lake revealed by EEM-PARAFAC: An insight into the fate of allochthonous DOM in alpine lakes affected by climate change.

    PubMed

    Du, Yingxun; Zhang, Yuanyuan; Chen, Feizhou; Chang, Yuguang; Liu, Zhengwen

    2016-10-15

    Due to climate change, tree line advance is occurring in many alpine regions. Within the next 50 to 100years, alpine lake catchments are expected to develop increased vegetation cover similar to that of sub-alpine lake catchments which currently exist below the tree line. Such changes in vegetation could trigger increased allochthonous DOM inputs to alpine lakes. To understand the fate of allochthonous DOM in alpine lakes impacted by climate change, the photochemical reactivity of DOM in sub-alpine Lake Tiancai (located 200m below the tree line) was investigated by excitation emission matrix fluorescence combined with parallel factor analysis (EEM-PARAFAC) and UV-Vis spectra analysis. With photo-exposure, a decrease in apparent DOM molecular weight was observed and 32% DOM was photomineralized to CO2. Interestingly, the aromaticity of DOM increased after photodegradation, as evidenced by increases in both the specific UV absorbance at 254nm (SUVA254) and the humification index (HIX). Five EEM-PARAFAC components were identified, including four terrestrially-derived substances (C1, C2, C3 and C4; allochthonous) and one tryptophan-like substance (C5; autochthonous). Generally, allochthonous DOM represented by C2 and C3 exhibited greater photoreactivity than autochthonous DOM represented by C5. C4 was identified as a possible photoproduct with relatively high aromaticity and photorefractive tendencies and contributed to the observed increase in SUVA254 and HIX. UV light facilitated the photodegradation of DOM and had the greatest effect on the removal of C3. This study provides information on the transformation of EEM-PARAFAC components in a sub-alpine lake, which is important in understanding the fate of increased allochthonous DOM inputs to alpine lakes impacted by climate change. PMID:27300561

  2. Are lake sediments mere archives of degraded organic matter? - evidence of rapid biotic changes tracked in sediments of pre-alpine Lake Lunz, Austria

    NASA Astrophysics Data System (ADS)

    Hollaus, Lisa-Maria; Khan, Samiullah; Schelker, Jakob; Ejarque, Elisabet; Battin, Tom; Kainz, Martin

    2016-04-01

    Lake sediments are used as sentinels of changes in organic matter composition and dynamics within lakes and their catchments. In an effort to investigate how past and recent hydrological extreme events have affected organic matter composition in lake sediments, we investigated the biogeochemical composition of sediment cores and settling particles, using sediment traps in the pre-alpine, oligotrophic Lake Lunz, Austria. We assessed annual sedimentation rates using 137Cs and 210Pb, time integrated loads of settling particles, analyze stable carbon (δ13C) and nitrogen (δ15N) isotopes to track changes of carbon sources and trophic compositions, respectively, and use source-specific fatty acids as indicators of allochthonous, bacterial, and algal-derived organic matter. Preliminary results indicate that settling particles of Lake Lunz (33 m depth) contain high algae-derived organic matter, as assessed by long-chain polyunsaturated fatty acids (LC-PUFA), indicating low degradation of such labile organic matter within the water column of this lake. However, LC-PUFA decreased rapidly in sediment cores below the sediment-water interface. Concentrations of phosphorous remained stable throughout the sediment cores (40 cm), suggesting that past changes in climatic forcing did not alter the load of this limiting nutrient in lakes. Ongoing work reveals dramatic biotic changes within the top layers of the sediment cores as evidenced by high numbers of small-bodied cladocerans (e.g., Bosmina) and large-bodied zooplankton (e.g., Daphnia) are only detected at lower sediment layers. Current research on these lake sediments is aimed at investigating how organic matter sources changed during the past century as a result of recorded weather changes.

  3. Promise and Pitfalls of Using Grain Size Analysis to Identify Glacial Sediments in Alpine Lake Cores.

    NASA Astrophysics Data System (ADS)

    Clark, D. H.

    2011-12-01

    Lakes fed by glacier outwash should have a clastic particle-size record distinct from non-glacial lakes in the same area, but do they? The unique turquoise color of alpine glacial lakes reflects the flux of suspended clastic glacial rock flour to those lakes; conversely, lakes not fed by outwash are generally clear with sediments dominated by organics or slope-wash from nearby hillslopes. This contrast in sediment types and sources should produce a distinct and measureable different in grain sizes between the two settings. Results from a variety of lakes suggest the actual situation is often more subtle and complex. I compare grain size results to other proxies to assess the value of grain size analysis for paleoglacier studies. Over the past 10 years, my colleagues and I have collected and analyzed sediment cores from a wide variety of lakes below small alpine glaciers in an attempt to constrain the timing and magnitude of alpine glaciation in those basins. The basic concept is that these lakes act as continuous catchments for any rock flour produced upstream by glacier abrasion; as a glacier grows, the flux of rock flour to the lake will also increase. If the glacier disappears entirely, rock flour deposition will also cease in short order. We have focused our research in basins with simple sedimentologic settings: mostly small, high-altitude, stripped granitic or metamorphic cirques in which the cirque glaciers are the primary source of clastic sediments. In most cases, the lakes are fed by meltwater from a modern glacier, but were ice free during the earlier Holocene. In such cases, the lake cores should record formation of and changes in activity of the glacier upstream. We used a Malvern Mastersizer 2000 laser particle size analyzer for our grain size analyses, as well as recording magnetic susceptibility, color, and organics for the same cores. The results indicate that although lakes often experience increases in silt and clay-size (<0.63 mm) clastic

  4. Abundance, Activity, and Diversity of Ammonia-oxidizing Bacteria and Archaea in Oligotrophic Alpine Lakes of Yosemite National Park, California

    NASA Astrophysics Data System (ADS)

    Beman, J.; Hayden, C.

    2013-12-01

    Lakes play critical roles in biogeochemical cycles as integrators of carbon and nitrogen cycling across watersheds. They are also ';sentinels' that may be strongly affected by environmental change--yet the responses of lake biogeochemical processes are dictated by microbial communities that we still know little about. We quantified nitrification rates, carbon respiration rates, and the abundance and diversity of involved microbes, within lakes located along an elevational gradient in Yosemite National Park, USA. Temperature, atmospheric nitrogen (N) deposition, and exposure to UV all vary along this transect, allowing us to test how these variables may act together to influence microbial biogeochemical processes. We found surprisingly high abundances of ammonia-oxidizing bacteria (AOB)--despite low nutrient conditions and high light levels that may favor other organisms, and/or inhibit AOB. We also examined community composition and diversity of AOB and ammonia-oxidizjng archaea (AOA) using Illumina sequencing of 16S rRNA genes, and measured ammonia oxidation rates using 15N tracer. All of these data are indicative of active N cycling by a dynamic microbial community. In Yosemite and other wilderness areas, atmospheric N deposition supplies a critical nutrient that may alter naturally nutrient-poor ecosystems; in the Sierra Nevada, much of this deposition occurs in the form of ammonium, suggesting a key role for nitrification in converting deposited N into more mobile forms. Our data indicate that oligotrophic alpine lakes may be nitrification hotspots in Yosemite.

  5. Bacterial GDGTs in Holocene sediments and catchment soils of a high Alpine lake: application of the MBT/CBT-paleothermometer

    NASA Astrophysics Data System (ADS)

    Niemann, H.; Stadnitskaia, A.; Wirth, S. B.; Gilli, A.; Anselmetti, F. S.; Sinninghe Damsté, J. S.; Schouten, S.; Hopmans, E. C.; Lehmann, M. F.

    2012-05-01

    A novel proxy for continental mean annual air temperature (MAAT) and soil pH, the MBT/CBT-paleothermometer, is based on the temperature (T) and pH-dependent distribution of specific bacterial membrane lipids (branched glycerol dialkyl glycerol tetraethers - GDGTs) in soil organic matter. Here, we tested the applicability of the MBT/CBT-paleothermometer to sediments from Lake Cadagno, a high Alpine lake in southern Switzerland with a small catchment of 2.4 km2. We analysed the distribution of bacterial GDGTs in catchment soils and in a radiocarbon-dated sediment core from the centre of the lake, covering the past 11 000 yr. The distribution of bacterial GDGTs in the catchment soils is very similar to that in the lake's surface sediments, indicating a common origin of the lipids. Consequently, their transfer from the soils into the sediment record seems undisturbed, probably without any significant alteration of their distribution through in situ production in the lake itself or early diagenesis of branched GDGTs. The MBT/CBT-inferred MAAT estimates from soils and surface sediments are in good agreement with instrumental values for the Lake Cadagno region (~0.5 °C). Moreover, downcore MBT/CBT-derived MAAT estimates match in timing and magnitude other proxy-based T reconstructions from nearby locations for the last two millennia. Major climate anomalies recorded by the MBT/CBT-paleothermometer are, for instance, the Little Ice Age (~14th to 19th century) and the Medieval Warm Period (MWP, ~9th to 14th century). Together, our observations indicate the quantitative applicability of the MBT/CBT-paleothermometer to Lake Cadagno sediments. In addition to the MWP, our lacustrine paleo T record indicates Holocene warm phases at about 3, 5, 7 and 11 kyr before present, which agrees in timing with other records from both the Alps and the sub-polar North-East Atlantic Ocean. The good temporal match of the warm periods determined for the central Alpine region with north

  6. Climate regulates alpine lake ice cover phenology and aquatic ecosystem structure

    NASA Astrophysics Data System (ADS)

    Preston, Daniel L.; Caine, Nel; McKnight, Diane M.; Williams, Mark W.; Hell, Katherina; Miller, Matthew P.; Hart, Sarah J.; Johnson, Pieter T. J.

    2016-05-01

    High-elevation aquatic ecosystems are highly vulnerable to climate change, yet relatively few records are available to characterize shifts in ecosystem structure or their underlying mechanisms. Using a long-term data set on seven alpine lakes (3126 to 3620 m) in Colorado, USA, we show that ice-off dates have shifted 7 days earlier over the past 33 years and that spring weather conditions—especially snowfall—drive yearly variation in ice-off timing. In the most well studied lake, earlier ice-off associated with increases in water residence times, thermal stratification, ion concentrations, dissolved nitrogen, pH, and chlorophyll a. Mechanistically, low spring snowfall and warm temperatures reduce summer stream flow (increasing lake residence times) but enhance melting of glacial and permafrost ice (increasing lake solute inputs). The observed links among hydrological, chemical, and biological responses to climate factors highlight the potential for major shifts in the functioning of alpine lakes due to forecasted climate change.

  7. Climate regulates alpine lake ice cover phenology and aquatic ecosystem structure

    USGS Publications Warehouse

    Preston, Daniel L.; Caine, Nel; McKnight, Diane M.; Williams, Mark W.; Hell, Katherina; Miller, Matthew P.; Hart, Sarah J.; Johnson, Pieter T.J.

    2016-01-01

    High-elevation aquatic ecosystems are highly vulnerable to climate change, yet relatively few records are available to characterize shifts in ecosystem structure or their underlying mechanisms. Using a long-term dataset on seven alpine lakes (3126 to 3620 m) in Colorado, USA, we show that ice-off dates have shifted seven days earlier over the past 33 years and that spring weather conditions – especially snowfall – drive yearly variation in ice-off timing. In the most well-studied lake, earlier ice-off associated with increases in water residence times, thermal stratification, ion concentrations, dissolved nitrogen, pH, and chlorophyll-a. Mechanistically, low spring snowfall and warm temperatures reduce summer stream flow (increasing lake residence times) but enhance melting of glacial and permafrost ice (increasing lake solute inputs). The observed links among hydrological, chemical, and biological responses to climate factors highlight the potential for major shifts in the functioning of alpine lakes due to forecasted climate change.

  8. Unexpected response of high Alpine Lake waters to climate warming.

    PubMed

    Thies, Hansjörg; Nickus, Ulrike; Mair, Volkmar; Tessadri, Richard; Tait, Danilo; Thaler, Bertha; Psenner, Roland

    2007-11-01

    Over the past two decades, we have observed a substantial rise in solute concentration at two remote high mountain lakes in catchments of metamorphic rocks in the European Alps. At Rasass See, the electrical conductivity increased 18-fold. Unexpectedly high nickel concentrations at Rasass See, which exceeded the limit in drinking water by more than 1 order of magnitude, cannot be related to catchment geology. We attribute these changes in lake water quality to solute release from the ice of an active rock glacier in the catchment as a response to climate warming. Similar processes occurred at the higher elevation lake Schwarzsee ob Sölden, where electrical conductivity has risen 3-fold during the past two decades. PMID:18044521

  9. Fluorscence signatures of dissolved organic material in an alpine lake ecosystem: responses to interannual climate variation and nutrient cycling

    NASA Astrophysics Data System (ADS)

    McKnight, Diane; Olivier, Matt; Hell, Katherina

    2016-04-01

    During snowmelt alpine lakes receive lower concentrations of dissolved organic material (DOM) that originates from the surrounding watershed than sub-alpine and montane lakes at lower elevations. Alpine lakes also have a shorter ice-free period that constrains the summer season of phytoplankton growth. Nonetheless, previous study of the reactive transport and production of DOM in an alpine lake in the Colorado Front Range during snowmelt and the summer ice-free season has shown that changes in DOM sources and the influence of biogeochemical processes can be resolved using fluorescence spectroscopy. Here we examine inter-annual variations in DOM fluorescence signatures during the snowmelt and summer periods in comparison to records of climate, residence time and primary production in the lake during the summer. Our analysis shows that variation in chlorophyll a concentration is a driver for variations in the fluorescence index (FI), as well as for specific ultra-violet absorbance. This result supports the predictions from the previous reactive transport modeling. We also conducted mesocosm experiments with nutrient enrichment to explore the role of nitrogen and phosphorus availability in influencing the fluorescence signature of DOM in summer. These results suggest that monitoring of simple spectroscopic properties of DOM can provide a means to track the biogeochemical consequences for alpine lakes of "too much" summer as climate continues to change.

  10. Anthropogenic nitrogen deposition induces rapid ecological changes in alpine lakes of the Colorado Front Range (USA)

    USGS Publications Warehouse

    Wolfe, A.P.; Baron, J.S.; Cornett, R.J.

    2001-01-01

    Recent sediments from two alpine lakes (> 3300 m asl) in the Colorado Front Range (USA) register marked and near-synchronous changes that are believed to represent ecological responses to enhanced atmospheric deposition of fixed nitrogen from anthropogenic sources. Directional shifts in sediment proxies include greater representations of mesotrophic diatoms and increasingly depleted ??15N values. These trends are particularly pronounced since ??? 1950, and appear to chronicle lake responses to excess N derived from agricultural and industrial sources to the east. The rate and magnitude of recent ecological changes far exceed the context of natural variability, as inferred from comparative analyses of a long core capturing the entire 14,000-year postglacial history of one of the lakes. Nitrogen deposition to these seemingly pristine natural areas has resulted in subtle but detectable limnological changes that likely represent the beginning of a stronger response to nitrogen enrichment.

  11. Diatom Community Changes in Five Sub-alpine Mountain Lakes in Northern California

    NASA Astrophysics Data System (ADS)

    Johnson, B.; Noble, P. J.; Howard, K.; Heyvaert, A.

    2012-12-01

    Sediment cores and/or phytoplankton sampling of five sub-alpine lakes within three northern California mountain ranges show a major shift in diatom phytoplankton communities over the past 20-60 years; however, specific causes of these changes are still under investigation. Diatom analysis of a 20-cm sediment core taken from Castle Lake, a meso-oligotrophic lake located on the eastern slope of the Klammath Mountains, shows the phytoplankton community shifted from being cyclotelloid-dominated to having a larger component of araphids beginning around 1997. In the lower 14 cm of the core, the phytoplankton are dominated by centric diatoms, including the Discostella stelligera-pseudostelligera group (>50% of total diatoms), and the Cyclotella occelata-rossii-tripartita complex (9-18%). The top 6 cm show an increasing shift towards araphids, including Asterionella formosa and the Fragilaria tenera-nanana group, which is consistent with phytoplankton in the lake's epilimnion today. Fallen Leaf Lake (FLL), located at the southern end of the Lake Tahoe basin, has also undergone a similar shift. Presently, A. formosa, the F. tenera-nananna group, and Tabellaria dominate the phytoplankton. Examination of a sediment core from FLL indicates that A. formosa has been present in high abundances since at least 1812. The most prominent shift in the FLL diatom population began in the 1950s when the centric diatoms (eg. Aulacoseira subarctica) declined significantly in favor of araphids. The F. tenera-nanana group was present in trace amounts before 1812 and dramatically increased in abundance after the 1950s. Sediment accumulation rates have increased steadily since 1950 and coincide with increases in lake development and recreational use. A. formosa is also present today in Gilmore Lake, a minimally human-impacted lake located in the watershed above FLL, and in the heavily impacted Manzanita Lake in the northwestern corner of Lassen Volcanic National Park (LAVO) at the southern end

  12. Climate Change and its Potential Consequences to the Thermodynamics of an Alpine Lake

    NASA Astrophysics Data System (ADS)

    Fink, G.

    2012-04-01

    The characteristics of mixing processes as well as duration, frequency, and stability of an alpine lake's stratification are strongly coupled to the local climate conditions. These physical processes then again define the way in which life - from bacteria to human being - develops in this environment. Hence, probably economic and cultural lake uses are affected by climate change. Studies discovered reactions of lake physics due to global warming in central Europe in measured time series. The question is: What changes in alpine lake's thermodynamic processes do we have to expect in the next decades? This question is directed at first to general lake properties like water temperature, metalimnion depth, and heat balance and their behavior in space and time. Secondly, there is a need for information about mixing processes in these monomictic lakes. Mixing is important for the distribution of e.g. nutrients and oxygen. Thus, it is necessary to know how mixing intensity changes under likely future climate conditions. For this purpose three representative lakes were selected: Lake Constance (international), Lago di Viverone (Italy), and Woerthersee (Austria). For each lake a 1dv hydrodynamic model was built up, calibrated with an evolutionary algorithm, and finally validated. The model's source code is in an experimental state and it was provided by Deltares (Netherlands). During calibration the calculated mean monthly temperatures in different depths were compared to measurements. Then, based upon measured meteorological data "what if"-scenarios of air temperature, wind speed, cloud cover and relative humidity were developed by changing the mean value or by removing the old trend and adding a new one. When driving the model with this broad range of meteorology the result is a sensitivity study. This allows the determination of the lake's sensitivity e.g. regarding mixing intensity on changing climate, in a way that is independent from rough regional climate projections

  13. Alpine Warming induced Nitrogen Export from Green Lakes Valley, Colorado Front Range, USA

    NASA Astrophysics Data System (ADS)

    Barnes, R. T.; Williams, M. W.; Parman, J.

    2012-12-01

    Alpine ecosystems are particularly susceptible to disturbance due to their short growing seasons, sparse vegetation and thin soils. Atmospheric nitrogen deposition and warming temperatures currently affect Green Lakes Valley (GLV) within the Colorado Front Range. Research conducted within the alpine links chronic nitrogen inputs to a suite of ecological impacts, resulting in increased nitrate export. According to NADP records at the site, the atmospheric flux of nitrogen has decreased by 0.56 kg ha-1 yr-1 since 2000, due to a decrease in precipitation. Concurrent with this decrease, alpine nitrate yields have continued to increase; by 32% relative to the previous decade (1990-1999). In order to determine the source(s) of the sustained nitrate increases we utilized long term datasets to construct a mass balance model for four stream segments (glacier to subalpine) for nitrogen and weathering product constituents. We also compared geochemical fingerprints of various solute sources (glacial meltwater, thawing permafrost, snow, and stream water) to alpine stream water to determine if sources had changed over time. Long term trends indicate that in addition to increases in nitrate; sulfate, calcium, and silica have also increased over the same period. The geochemical composition of thawing permafrost (as indicated by rock glacial meltwater) suggests it is the source of these weathering products. Mass balance results indicate the high ammonium loads within glacial meltwater are rapidly nitrified, contributing approximately 0.45 kg yr-1 to the NO3- flux within the upper reaches of the watershed. The sustained export of these solutes during dry, summer months is likely facilitated by thawing cryosphere providing hydraulic connectivity late into the growing season. In a neighboring catchment, lacking permafrost and glacial features, there were no long term weathering or nitrogen solute trends; providing further evidence that the changes in alpine chemistry in GLV are likely

  14. Particle-Dissolved Phase Partition of Polychlorinated Biphenyls in High Altitude Alpine Lakes.

    PubMed

    Nellier, Yann-Michel; Perga, Marie-Elodie; Cottin, Nathalie; Fanget, Philippe; Naffrechoux, Emmanuel

    2015-08-18

    We investigated whether polychlorinated biphenyls (PCBs) partitioning between the dissolved and particulate phases in two high altitude alpine lakes was determined by the quantity, size structure, or composition of suspended particles. Within- and between-lakes differences in water-particulate phase partition coefficient (Kp) were not related to total suspended matter, phytoplankton biomass, or taxonomic composition. Yet, a seasonal relationship between Kp and Kow was detected for both lakes, revealing equilibrium of PCBs partition when lakes were ice covered. On the contrary, PCBs partitioning between particles and water appeared kinetically limited during the open water season. Partition is therefore mainly governed by thermodynamic laws during the ice-covered period, while none of the tested physical or biological parameters seemed to explain the distribution of these particle-reactive contaminants in the open water period. PCBs were always mainly associated with particulate matter, but partitioning within different particulate size-fractions varied between seasons and between years during open water periods. When ice cover is absent, PCBs were mainly adsorbed on microplankton, the largest phytoplanktonic size fraction, which is the least likely to get grazed by pelagic microconsumers. PMID:26189929

  15. Aerosol Generation and Circulation in the Shore Zone of a Large Alpine Lake - Lake Tahoe, CA.

    NASA Astrophysics Data System (ADS)

    Vancuren, R. A.; Pederson, J. R.; Lashgari, A.; Dolislager, L.; McCauley, E.

    2007-12-01

    The temporal, spatial, and size-distribution patterns of particles in ambient air over shore areas and the surface of Lake Tahoe (Nevada and California) were studied as part of the 2003-2004 Lake Tahoe Atmospheric Deposition Study (LTADS). The concentration of population along the shoreline of Lake Tahoe makes accurate characterization of local aerosol generation and transport especially important in estimation of annual particle flux onto the surface of the lake. Road dust and smoke are major components of aerosols around the lake, and strong gradients in concentrations and size distributions occur as functions of location, land use, traffic activity, and time of day. Measurements taken while cruising on the lake show that aerosol concentrations in near-shore areas are primarily controlled by a combination of diurnal cycling of land- and lake- breezes coupled with varying particle emissions driven by cycles of human activity. Source-associated particle size distributions were shown to be conserved over wide ranges of particle concentrations. Particle concentrations over water were shown to be highly localized, with highest concentrations just offshore from urbanized areas, lowest concentrations along undeveloped shoreline, and low-to-intermediate concentrations over the middle areas of the lake. Based in part on these observations, particle deposition to the lake is seen to be dominated by mesoscale processes, with only minor contributions from regional or large scale atmospheric circulation.

  16. Effects of oligotrophication on primary production in peri-alpine lakes

    NASA Astrophysics Data System (ADS)

    Finger, David; Wüest, Alfred; Bossard, Peter

    2013-08-01

    During the second half of the 20th century untreated sewage released from housing and industry into natural waters led to a degradation of many freshwater lakes and reservoirs worldwide. In order to mitigate eutrophication, wastewater treatment plants, including Fe-induced phosphorus precipitation, were implemented throughout the industrialized world, leading to reoligotrophication in many freshwater lakes. To understand and assess the effects of reoligotrophication on primary productivity, we analyzed 28 years of 14C assimilation rates, as well as other biotic and abiotic parameters, such as global radiation, nutrient concentrations and plankton densities in peri-alpine Lake Lucerne, Switzerland. Using a simple productivity-light relationship, we estimated continuous primary production and discussed the relation between productivity and observed limnological parameters. Furthermore, we assessed the uncertainty of our modeling approach based on monthly 14C assimilation measurements using Monte Carlo simulations. Results confirm that monthly sampling of productivity is sufficient for identifying long-term trends in productivity and that conservation management has successfully improved water quality during the past three decades via reducing nutrients and primary production in the lake. However, even though nutrient concentrations have remained constant in recent years, annual primary production varies significantly from year to year. Despite the fact that nutrient concentrations have decreased by more than an order of magnitude, primary production has decreased only slightly. These results suggest that primary production correlates well to nutrients availability but meteorological conditions lead to interannual variability regardless of the trophic status of the lake. Accordingly, in oligotrophic freshwaters meteorological forcing may reduce productivity impacting on the entire food chain of the ecosystem.

  17. Transport of pollutants from cow feedlots in eastern Colorado into Rocky Mountain alpine lakes

    NASA Astrophysics Data System (ADS)

    Pina, A.; Denning, S.; Schumacher, R. S.

    2012-12-01

    Concentrated Animal Feeding Operations (CAFOs), also called factory farms, are known for raising tens of millions head of livestock including cows (beef and dairy), swine, and poultry. With as many as 250 head of cattle per acre, a United States Department of Agriculture's (USDA) Agricultural Research Service (ARS) report showed beef cattle from CAFOs in the United States produce as much as 24.1 million tons of manure annually. Gases released from cow manure include methane (CH4), nitrous oxide (N2O), hydrogen sulfide (H2S), and ammonia (NH3). During boreal summers Colorado experiences fewer synoptic weather systems, allowing the diurnal cycle to exert greater control of meteorological events along the mountain-plains interface. Anabatic, or upslope winds induced by the diurnal cycle, contribute largely to the transport of gases and particulates from feedlots in eastern Colorado into the Rocky Mountains, presenting a potential harm to natural alpine ecosystems. This study focuses on locating the source of transport of gases from feedlots along the eastern Front Range of Colorado into alpine lakes of the Rocky Mountains. Source regions are approximated using backward time simulation of a Lagrangian Transport model.

  18. Tropical high-altitude Andean lakes located above the tree line attenuate UV-A radiation more strongly than typical temperate alpine lakes.

    PubMed

    Aguilera, Ximena; Lazzaro, Xavier; Coronel, Jorge S

    2013-09-01

    Tropical high-altitude Andean lakes are physically harsh ecosystems. Located above the treeline (≥4000 m a.s.l.), they share common features with temperate alpine lakes, which impose extreme conditions on their aquatic organisms: e.g., strong winds, broad diel variations in water temperature, and intense solar ultraviolet radiation (UVR). However, because of their latitude, they differ in two major ecological characteristics: they lack ice cover during the winter and they do not present summer water column stratification. We sampled 26 tropical high-altitude Andean lakes from three regions of the Bolivian Eastern Andes Cordillera during the wet period (austral summer). We performed an ordination to better describe the typology of Andean lakes in relation to the environmental variables, and we assessed the relationships among them, focussing on the UV-A transparency (360 nm) throughout the water column. We found a positive correlation between UV-A transparency calculated as Z(1%) (the depth which reaches 1% of the surface UV-A), the lake maximum depth and Secchi transparency (r = 0.61). Z(1%) of UV-A was smaller in shallow lakes than in deep lakes, indicating that shallow lakes are less transparent to UV-A than deep lakes. We hypothesize that, compared to shallow lakes, deep lakes (maximum depth > 10 m) may have lower dissolved organic carbon (DOC) concentrations (that absorb UV radiation) due to lower temperature and reduced macrophyte cover. Based on our data, tropical high-altitude Andean lakes are less transparent to UV-A (K(d) range = 1.4-11.0 m(-1); Z(1%) depth range = 0.4-3.2 m) than typical temperate alpine lakes (1-6 m(-1), 3-45 m, respectively). Moreover, they differ in vertical profiles of UV-A, chlorophyll-a, and temperature, suggesting that they may have a distinct ecological functioning. Such peculiarities justify treating tropical high-altitude Andean lakes as a separate category of alpine lakes. Tropical high-altitude Andean lakes have been poorly

  19. Rock glaciers as a source of nitrate to alpine streams, Green Lakes Valley, Colorado, USA.

    NASA Astrophysics Data System (ADS)

    Knauf, M.; Williams, M. W.; Caine, N.

    2003-12-01

    An ongoing concern in alpine areas of the western United States is the high concentrations of nitrate in surface waters. A number of research scientists have shown that talus areas are one source of this elevated nitrate (Williams et al., 1997; Campbell et al., 2002). Here we evaluate the potential contribution of nitrate to surface waters from a previously overlooked source: rock glaciers. Water draining from the Green Lake 5 rock glacier in the Colorado Front Range has been sampled for nitrate and ammonium since 1998 as part of the Niwot Ridge LTER program. The mean concentration of nitrate in stream waters in the Green Lakes Valley is 16.12 ueq/L, and for talus streams is 20 ueq/L. In comparison, the stream draining the rock glacier has an average nitrate concentration of 54 ueq/L. Moreover, nitrate values from the stream draining the rock glacier peak in the late summer at over 100 ueq/L. The sources of these high nitrate values from the rock glacier are unknown at this time; we evaluate several hypotheses. Increased nitrate could be a result of dry deposition on the rock glacier that is flushed during snowmelt and rain events. Another hypothesis is that microbial processes within the rock glacier have contribute to higher nitrate concentrations. Here we evaluate the sources and fate of nitrate in waters draining the Green Lake 5 rock glacier in 2003 using a combination of stable (delta O18) and radiogenic (tritium) water isotopes, fractionation of dissolved organic matter, fluorescence index of dissolved organic matter, and mineralization experiments. These site-specific results are then placed in a regional context through a synoptic sampling of streams draining rock glaciers throughout the Rocky Mountain region. Works Cited Williams, M. W., T. Davinroy, and P. D. Brooks. 1997. Organic and inorganic nitrogen pools in talus soils and water, Green Lakes Valley, Colorado Front Range, Hydrologic Processes, 11(13): 1747-1760. Campbell, Donald H., Carol Kendall

  20. Long-term EC measurements over a pre-alpine lake

    NASA Astrophysics Data System (ADS)

    Scholz, Katharina; Hammerle, Albin; Wohlfahrt, Georg

    2016-04-01

    Recent research indicates that inland waters are significant contributors to the global carbon cycle. However, up to now long-term measurements of carbon dioxide (CO2) and methane (CH4) fluxes above freshwater ecosystems are sparse and the knowledge on the magnitude of the fluxes and the involved processes needs to be improved. Most of the research has focused on tropical and boreal regions. Furthermore, many findings were based on short-term measurements or relied on non-continuous floating chamber measurements. This study is part of a cooperation project with the overarching aim to study possible effects of past, present and future hydrological extremes on carbon fluxes at catchment scale. The first step is to establish the complete carbon balance of a lake and therefore also to measure CO2 exchange between the atmosphere and the surface of a temperate lake for the first time continuously all year round. The eddy covariance method is a technique widely used for long-term, continuous measurements of energy and trace gas exchange between the atmosphere and terrestrial ecosystems. Here, we employ this method for year-round monitoring of CO2-, sensible and latent heat fluxes above Lake Lunz, a small pre-alpine lake in lower Austria. In addition, the water temperature profile was measured with high temporal resolution in order to capture the heat storage change of the lake during the ice free period. This together with measurements of the net radiation allows us to also evaluate the energy balance closure. The measurements started in December 2014 and here we present flux data as well as data on the energy balance closure of the first year. A preliminary analysis of the data indicated that the lake acts as a net source of CO2 with stronger emissions during night. The monthly mean amplitudes of the sensible (H) and latent (LE) heat flux were highest during the summer month (July, August), with a clear peak of H in the early morning hours. The water temperature profile

  1. Biogeochemical responses of two alpine lakes to climate change and atmospheric deposition, Jasper and Banff National Parks, Canadian Rocky Mountains

    NASA Astrophysics Data System (ADS)

    Hobbs, W.; Vinebrooke, R. D.; Wolfe, A. P.

    2012-12-01

    The sensitivity of remote alpine ecosystems to global change has been documented by 20th century changes in climate, glacial recession, and terrestrial and aquatic ecosystems. In many cases the magnitude and dominance of abiotic drivers on recent changes in alpine lakes is often mediated by processes within the hydrologic catchment. Here we present sedimentary records of biogeochemical responses in two alpine lake ecosystems to multiple environmental drivers over the last ~ 500 years in Banff and Jasper National parks. We combine paleoecological measures of primary production (fossil microbial pigments) and diatom community structure with geochemical proxies of reactive N (Nr) deposition to describe the nature and rate of recent ecosystem changes. Curator Lake in Jasper shows a strong diatom response to the limnological effects of climate warming (e.g. thermal stratification), but little evidence of changes in Nr cycling over the last ~500 years. The response of McConnell Lake in Banff to climate change is strongly mediated by glacial activity within the catchment, and changing inputs of Nr. Our findings highlight the range of limnological responses that may be expressed by similar ecosystems subjected to comparable abiotic stressors, while further documenting the magnitude of the ecological footprint associated with recent environmental change in mountain park environments.

  2. A satellite-based climatology of European alpine lake surface water temperature for the period 1989-2013

    NASA Astrophysics Data System (ADS)

    Riffler, M.; Lieberherr, G.; Wunderle, S.

    2014-12-01

    Lake water temperature (LWT) is an important driver of lake ecosystems and it has been identified as an indicator of climate change. At some European lakes LWT has been observed over several decades, but the majority of lakes is not monitored, or only on a non-regular basis, which is insufficient to track a climate signal. Satellite observations might be utilized to fill these gaps, however, only few satellite sensors offer the possibility to analyze time series which cover 25 years or more. The Advanced Very High Resolution Radiometer (AVHRR) is among these and has been flown as a heritage instrument for almost 35 years. It will be carried on for at least ten more years finally offering a unique opportunity for satellite-based climate studies. We present a satellite-based lake surface water temperature (LSWT) data set for European (pre-alpine) water bodies based on the extensive AVHRR 1 km data record (1989-2013) of the Remote Sensing Research Group at the University of Bern, Switzerland. It has been compiled out of AVHRR/2 (NOAA-07, -09, -11, -14) and AVHRR/3 (NOAA-16, -17, -18, -19 and Metop-A) day and night time data. We will discuss the processing steps (e.g. geolocation, calibration, LSWT algorithm, etc.) which are necessary to obtain the accuracy needed for climate related studies. The resulting climatology covers pre-alpine and alpine lakes with sizes between 14 and 580 km2. We will present and discuss the analysis of trends for some sample lakes in various regions of the Alps.

  3. Long-term trends of chemical and modelled photochemical parameters in four Alpine lakes.

    PubMed

    Minella, Marco; Leoni, Barbara; Salmaso, Nico; Savoye, Liliane; Sommaruga, Ruben; Vione, Davide

    2016-01-15

    Based on long-term trends of water chemistry parameters of photochemical significance from four lakes located in the Alps (Iseo, Garda, Piburgersee, Geneva), we calculated the corresponding steady-state concentrations of photoinduced transient species with an ad-hoc photochemical model. Such transients were the hydroxyl ((•)OH) and carbonate (CO3(-•)) radicals, singlet oxygen ((1)O2), and the triplet states of chromophoric dissolved organic matter ((3)CDOM*). Among the investigated lakes, Lake Iseo, for example, showed a long-term near-stability in chemical parameters that resulted in a photochemical stability. By contrast, Piburgersee underwent important chemical modifications, but the interplay of compensation (parallel increase of both inorganic and organic carbon) and near-saturation effects (organic matter as main (•)OH source and sink) prevented the modelled photochemistry to undergo significant shifts over time. This result suggests the occurrence of a sort of "photochemical buffering" in some lake ecosystems, which would dampen modifications of the steady-state concentration of the photochemically-formed reactive transients, even in the case of significant changes in water chemistry. Finally, in lakes Garda and Geneva, long-term changes in water chemistry had an effect on photochemistry. While in Lake Garda the small increase in DOM was associated to a small increase in (1)O2 and (3)CDOM*, in Lake Geneva, the increases in pH and bicarbonate and the decrease in nitrite resulted in an (•)OH decrease. Overall, our results predict very different lake photochemistry patterns in relation to alterations in water chemistry parameters caused by climate change, such as changes in water alkalinity and dissolved organic carbon concentration. PMID:26410700

  4. An Investigation of the Impacts of Climate and Environmental Change on Alpine Lakes in the Uinta Mountains, Utah

    NASA Astrophysics Data System (ADS)

    Moser, K. A.; Hundey, E. J.; Porinchu, D. F.

    2007-12-01

    Aquatic systems in alpine and sub-alpine areas of the western United States are potentially impacted by atmospheric pollution and climate change. Because these mountainous regions are an important water resource for the western United States, it is critical to monitor and protect these systems. The Uinta Mountains are an east- west trending mountain range located on the border between Utah, Wyoming and Colorado and downwind of the Wasatch Front, Utah, which is characterized by a rapidly expanding population, as well as mining and industry. This alpine area provides water to many areas in Utah, and contributes approximately nine percent of the water supply to the Upper Colorado River. Our research is focused on determining the impacts of climate change and pollution on alpine lakes in the Uinta Mountains. The results presented here are based on limnological measurements made at 64 Uinta Mountain lakes spanning a longitude gradient of one degree and an elevation gradient of 3000 feet. At each lake maximum depth, conductivity, salinity, pH, Secchi depth, temperature, alkalinity, and concentrations of major anions, cations and trace metals were measured. Principal Components Analysis (PCA) was performed to determine relationships between these variables and to examine the variability of the values of these variables. Our results indicate that steep climate gradients related to elevation and longitude result in clear differences in limnological properties of the study sites, with high elevation lakes characterized by greater amounts of nitrate and nitrite compared to low elevation sites. As well, diatoms in these lakes indicate that many high elevation sites are mesotrophic to eutrophic, which is unexpected for such remote aquatic ecosystems. We hypothesize that elevated nitrate and nitrite levels at high elevation sites are related to atmospherically derived nitrogen, but are being exacerbated relative to lower elevation sites by greater snow cover and reduced plant

  5. Dissolved greenhouse gas concentrations as proxies for emissions: First results from a survey of 43 Alpine lakes

    NASA Astrophysics Data System (ADS)

    Pighini, Sylvie; Wohlfahrt, Georg; Miglietta, Franco

    2015-04-01

    Up to very recently, freshwater ecosystems were neglected in assessments of the global carbon cycle and considered merely as passive 'pipes' which transport carbon from the land to the oceans. This view has been challenged by an increasing number of studies showing that freshwater ecosystems may negate a substantial fraction of the carbon sink through carbon dioxide (CO2) and in particular methane (CH4) emissions and thus rather should be viewed as 'reactors' which process a large fraction of the terrigenous carbon. Most of our knowledge on freshwater CO2 and CH4 emissions to date derives from studies in tropical and boreal regions, while temperate freshwater ecosystems are understudied. This study is focused on lakes from the Alpine area and their content in dissolved greenhouse gases, CH4 and CO2. We mostly aim to assess the content of dissolved methane and carbon dioxide from the Alpine lakes in order to understand whether Alpine lakes could be potential CH4 and CO2 emitters. We also would like to relate concentrations to lake characteristics and potential biotic and abiotic driving forces. A diverse set of 43 lakes, from Trentino, South Tirol (Italy) and North Tirol (Austria), was selected resulting in a gradient with respect to elevation (from 240 to 1700 m a.s.l.) and latitude (from 45.52° to 47.38°). Complementary to dissolved CH4 and CO2 surface water samples, dissolved oxygen and temperature were measured. Only water surface samples were considered. Analyses were done with a gas chromatographer equipped with a flame ionization detector (FID) for CH4 and a thermal conductivity detector (TCD) for CO2 determination. The first results show that all the sampled lakes were super-saturated in dissolved methane and carbon dioxide concentrations, at least partly to a degree that in the literature has been shown to result in substantial emissions to the atmosphere. To estimate emissions, CO2 and CH4 fluxes will be quantified using the eddy covariance and floating

  6. Climate and Environmental Changes Over the Past 150 years Inferred from Two Alpine Lakes in the Eastern Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Zhao, C.; Yang, X.

    2014-12-01

    Current global warming and human activities may exert profound effects on lacustrine environment and ecosystem. However, limited data have been reported to show how lake systems have responded to changes in climate and human disturbances. Here we report multi-proxy climate and environmental data for the past ~150 years from two small alpine lakes with similar size and hydrology at the eastern margin of the Tibetan Plateau, a place influenced by the Indian summer monsoon. One is Jiren Lake (4500 m asl), above the modern tree line and undisturbed by any human activity in history. Another is Cuoqia Lake (3900 m asl), just below the tree line and only experienced an deforestation and reforestation process by human activity over the past centuries. We use hydrogen isotopes of C28-fatty acid and TOC as proxies for changes in monsoon precipitation and lake productivity, respectively. Our data indicate both lakes have experienced similar variations in monsoon precipitation over the past 150 years, resembling the temperature variations in the northern Hemisphere. On the other hand, both lakes show very different changes in lake productivity. Productivity at Jiren Lake was stable before 1920AD and then shifted to an increasing trend, which coincides with our precipitation record and reveals the lake ecosystem being largely controlled by natural climate change. At Cuoqia Lake, the lake productivity gradually decreased until ~1980AD and then increased until now, largely following the local deforestation and reforestation process. Overall, our preliminary data probably indicate that human activities may have a stronger influence than natural climate change on lacustrine ecosystems.

  7. Genetic Diversity and Hybridisation between Native and Introduced Salmonidae Fishes in a Swedish Alpine Lake.

    PubMed

    Faulks, Leanne; Östman, Örjan

    2016-01-01

    Understanding the processes underlying diversification can aid in formulating appropriate conservation management plans that help maintain the evolutionary potential of taxa, particularly under human-induced activities and climate change. Here we assessed the microsatellite genetic diversity and structure of three salmonid species, two native (Arctic charr, Salvelinus alpinus and brown trout, Salmo trutta) and one introduced (brook charr, Salvelinus fontinalis), from an alpine lake in sub-arctic Sweden, Lake Ånn. The genetic diversity of the three species was similar and sufficiently high from a conservation genetics perspective: corrected total heterozygosity, H'T = 0.54, 0.66, 0.60 and allelic richness, AR = 4.93, 5.53 and 5.26 for Arctic charr, brown trout and brook charr, respectively. There were indications of elevated inbreeding coefficients in brown trout (GIS = 0.144) and brook charr (GIS = 0.129) although sibling relationships were likely a confounding factor, as a high proportion of siblings were observed in all species within and among sampling locations. Overall genetic structure differed between species, Fst = 0.01, 0.02 and 0.04 in Arctic charr, brown trout and brook charr respectively, and there was differentiation at only a few specific locations. There was clear evidence of hybridisation between the native Arctic charr and the introduced brook charr, with 6% of individuals being hybrids, all of which were sampled in tributary streams. The ecological and evolutionary consequences of the observed hybridisation are priorities for further research and the conservation of the evolutionary potential of native salmonid species. PMID:27032100

  8. Genetic Diversity and Hybridisation between Native and Introduced Salmonidae Fishes in a Swedish Alpine Lake

    PubMed Central

    Faulks, Leanne; Östman, Örjan

    2016-01-01

    Understanding the processes underlying diversification can aid in formulating appropriate conservation management plans that help maintain the evolutionary potential of taxa, particularly under human-induced activities and climate change. Here we assessed the microsatellite genetic diversity and structure of three salmonid species, two native (Arctic charr, Salvelinus alpinus and brown trout, Salmo trutta) and one introduced (brook charr, Salvelinus fontinalis), from an alpine lake in sub-arctic Sweden, Lake Ånn. The genetic diversity of the three species was similar and sufficiently high from a conservation genetics perspective: corrected total heterozygosity, H’T = 0.54, 0.66, 0.60 and allelic richness, AR = 4.93, 5.53 and 5.26 for Arctic charr, brown trout and brook charr, respectively. There were indications of elevated inbreeding coefficients in brown trout (GIS = 0.144) and brook charr (GIS = 0.129) although sibling relationships were likely a confounding factor, as a high proportion of siblings were observed in all species within and among sampling locations. Overall genetic structure differed between species, Fst = 0.01, 0.02 and 0.04 in Arctic charr, brown trout and brook charr respectively, and there was differentiation at only a few specific locations. There was clear evidence of hybridisation between the native Arctic charr and the introduced brook charr, with 6% of individuals being hybrids, all of which were sampled in tributary streams. The ecological and evolutionary consequences of the observed hybridisation are priorities for further research and the conservation of the evolutionary potential of native salmonid species. PMID:27032100

  9. Bacterial GDGTs in Holocene sediments and catchment soils of a high-alpine lake: application of the MBT/CBT-paleothermometer

    NASA Astrophysics Data System (ADS)

    Niemann, H.; Stadnitskaia, A.; Wirth, S. B.; Gilli, A.; Anselmetti, F. S.; Sinninghe Damsté, J. S.; Schouten, S.; Hopmans, E. C.; Lehmann, M. F.

    2012-04-01

    A novel proxy for continental mean annual air temperature (MAAT) and soil-pH, the MBT/CBT-paleothermometer, is based on the temperature (T) and pH-dependent distribution of specific bacterial membrane lipids (branched glycerol dialkyl glycerol tetraethers - GDGTs) in soil organic matter. Here, we tested the applicability of the MBT/CBT-paleothermometer to sediments from Lake Cadagno, a small high-alpine lake in southern Switzerland with a small catchment of 2.4 km2. We analysed the distribution of bacterial GDGTs in catchment soils and in a radiocarbon-dated sediment core, which covers the entire Holocene. The composition of bacterial GDGTs in soils are almost identical to that in the lake's surface sediments, indicating a common origin of the lipids. Consequently, the transfer of GDGTs from the soils into the sediment record seems undisturbed, probably without any significant alteration through in situ production or early diagenesis. This could be related to the euxinic conditions of Lake Cadagno, which persisted over the entire Holocene. The MBT/CBT-inferred MAAT-estimates from soils and surface sediments are in good agreement with instrumental values for the Lake Cadagno region (~ 0.5 °C). Moreover, downcore MBT/CBT-derived MAAT-estimates match in timing and magnitude other proxy-based T-reconstructions from nearby locations for the last two millennia. Major climate anomalies recorded by the MBT/CBT-paleothermometer are, for instance, the Little Ice Age (~14th to 19th century) and the Medieval Warm Period (~10th to14th century). Together, our observations indicate a high potential to use branched GDGTs in Lake Cadagno sediments for paleo-climate reconstructions. Consistent with other T-records from both the Alps and from the subpolar NE-Atlantic, our lacustrine paleotemperature record indicates Holocene MAAT-variations with T-highs at ~1, 3, 5, 7, and 11 kyr BP. The good temporal match of the warm periods determined for the S-Alpine region with NW

  10. Persistent organic pollutants, brominated flame retardants and synthetic musks in fish from remote alpine lakes in Switzerland.

    PubMed

    Schmid, Peter; Kohler, Martin; Gujer, Erika; Zennegg, Markus; Lanfranchi, Marco

    2007-04-01

    Remote alpine lakes do not receive any direct aquatic inputs from anthropogenic activities. Therefore, these ecosystems may receive persistent organic compounds (POPs) by direct atmospheric deposition, only. Consequently, fish dwelling in these ecosystems represent an excellent indicator for the long-term atmospheric input of bioaccumulating and persistent contaminants. In the present study, fish from seven remote alpine lakes, located between 2062 and 2637 m above sea level in south eastern Switzerland (Grisons), were investigated. Lipid-based fish tissue concentrations of pesticides including dichlorodiphenyltrichloroethane (DDT) and its transformation products (2,4'-DDT, 4,4'-DDT, 2,4'-dichlorodiphenyldichloroethane (DDD), 4,4'-DDD, 2,4'-dichlorodiphenyldichloroethene (DDE), 4,4'-DDE), as well as dieldrin, heptachlor exo-epoxide (HPEX), hexachlorobenzene (HCB), hexachlorocyclohexanes (HCH), polychlorinated biphenyls (PCB), polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F), and polybrominated diphenyl ethers (PBDE) were measured. In addition, seven synthetic musk compounds (Crysolide (ADBI), Phantolide (AHMI), Fixolide (AHTN), Traseolide (ATII), Galaxolide (HHCB), musk ketone (MK), and musk xylene (MX)) were determined. Concentrations of PCB, PCDD/F, and PBDE were in the same range as in fish from the major lakes situated in the Swiss plateau, indicating mainly atmospheric input of these persistent compounds. In contrast, concentrations of synthetic musks which are used as fragrances in laundry detergents and cosmetic products were distinctly lower than concentrations in fish from Swiss plateau lakes which receive inputs from waste water treatment plants. PMID:17207835

  11. Historical trends of anthropogenic metals in Eastern Tibetan Plateau as reconstructed from alpine lake sediments over the last century.

    PubMed

    Bing, Haijian; Wu, Yanhong; Zhou, Jun; Li, Rui; Wang, Jipeng

    2016-04-01

    Reconstructing trace metal historical trends are essential for better understanding anthropogenic impact on remote alpine ecosystems. We present results from an alpine lake sediment from the Eastern Tibetan Plateau to decipher the accumulation history of cadmium (Cd), lead (Pb) and zinc (Zn) over last century, from the preindustrial to the modern period. Cd, Pb and Zn in the sediment of Caohaizi Lake clearly suffered from atmospheric deposition, and the mining and smelting were regarded as the main anthropogenic sources. Since the mid-1990s, over 80% of trace metals were quantified from anthropogenic emissions. The temporal trends of anthropogenic metal fluxes showed that the contamination history of Pb was earlier than that of Cd and Zn, which was in agreement with the regional Pb emission history, but lagged behind the Pb decline in Europe and North America. The fluxes of anthropogenic Cd and Zn were relatively constant until the 1980s, increased sharply between the 1980s and the mid-1990s, and then kept the high values. The anthropogenic fluxes of Pb showed a marked rise around 1950, and increased sharply in the 1980s. In the mid-1990s, this flux reached the peak, and then decreased gradually. The Pb deposition flux at present in comparison with other lake records in the areas of Tibetan Plateau further demonstrated that trace metals in the Caohaizi Lake region were probably from Southwest China and South Asia. Economic development in these regions still puts pressure on the remote alpine ecosystems, and thus the impact of trace metals merits more attention. PMID:26807941

  12. Lakes as organic matter upgraders - seasonal variation in biochemical compositions of in- and outflowing particles in pre-alpine Lake Lunz, Austria

    NASA Astrophysics Data System (ADS)

    Khan, Samiullah; Hollaus, Lisa-Maria; Schelker, Jakob; Ejarque, Elisabet; Battin, Tom; Kainz, Martin

    2016-04-01

    Lakes are typically recharged by inflowing stream water and discharge into outflowing streams. In this multiannual field study on pre-alpine, oligotrophic Lake Lunz, Lower Austria, we hypothesized that, irrespective of seasons, stream water recharging the lake contains predominantly recalcitrant particular organic matter (POM; >1.2 um particle size), whereas outflowing lake water is mostly composed of more labile, algae-derived POM. We collected POM for 3 years (2013-2015) at a monthly basis from the inflowing and outflowing streams of Lake Lunz, analyzed POM content, its carbon and nitrogen, their stable isotopes, and fatty acids as biochemical indicators of POM sources. Preliminary results show that, independent of seasons, inflowing POM is rich in terrestrial markers, as evidenced by long-chain saturated fatty acids (>C22:0), with little contribution of autochthonous stream POM, such as algae-derived long-chain polyunsaturated fatty acids (LC-PUFA). However, POM in outflowing water contained considerably less terrestrial markers, but clearly higher contents of highly nutritious, algae-derived LC-PUFA. These results suggest that oligotrophic Lake Lunz acts as a biochemical upgrader within the fluvial network of this drainage basin and supplies highly nutritional POM to consumers further downstream. Ongoing research is aimed at identifying how much of the terrestrial and autochthonous POM is retained and processed in the lake (biota, sediments, or respired).

  13. Holocene lake level fluctuations of a small alpine lake in the Qilian Mountains, NW China: a comparison of chironomid, ostracod, pollen and geochemistry data.

    NASA Astrophysics Data System (ADS)

    Mischke, S.; Herzschuh, U.

    2003-04-01

    A core of 14 m length was drilled in a small alpine lake in the Qilian Mountains, NW China. The lake Luanhaizi has a drainage area of about 30 km2 and is situated at an altitude of 3200 m which represents the altitude of the present regional upper timberline. Due to the small size of the open-basin lake (surface area about 1 km2) and the sharply outlined catchment area the lake is regarded as a very sensitively and rapidly responding ecosystem. Analyses of ostracod shells, head capsules of larval chironomids and pollen and spores were conducted and the organic and carbonate content (LOI), element concentrations and magnetic susceptibility of core samples determined. Ostracod taxa mainly comprise Candona candida, C. neglecta, C. rawsoni, Cyclocypris ovum, Cypridopsis vidua, Fabaeformiscandona caudata, F. danielopoli, F. hyalina, Herpetocypris chevreuxi, Heterocypris salina, Ilyocypris cf. bradyi, I. echinata, I. lacustris and Limnocythere inopinata. They may be used to distinguish periods of low lake levels corresponding to a dense cover of aquatic plants at the lake bottom from stages of higher lake levels and a corresponding decrease in macrophytes at the core site. Chironomid taxa belonging to Chironomus, Cladopelma, Glyptotendipes, Micropsectra, Paratanytarsus, Polypedilum, Psectrocladius and Tanytarsus further provide information on variations in benthic oxygen availability and lake level fluctuations. Several units of the core show high abundances of pollen and spores of higher aquatic and wetland plants and fungi (Cyperaceae, Hippuris, Myriophyllum and Glomus) indicating low lake levels. In contrast, algae such as Botryococcus, Pediastrum and Tetraedron were regarded to reflect higher water levels. Typha angustifolia-type, Typha latifolia, Alisma and Potamogeton were recorded in low abundances as well. The organic content of core samples averages 6 % displaying four alternating stages of distinct minima and maxima. Lowest values of about 1 % occur at the core

  14. Responses of arctic and alpine ecosystems to altered seasonality under climate change

    NASA Astrophysics Data System (ADS)

    Ernakovich, J. G.; Hopping, K. A.; Berdanier, A.; Simpson, R. T.; Kachergis, E. J.; Steltzer, H.; Wallenstein, M. D.

    2012-12-01

    Arctic and alpine ecosystems are largely structured by strong seasonal patterns in abiotic drivers, including solar radiation and air and soil temperature. Because air temperature and precipitation patterns are changing rapidly, the length of the growing season is increasing due to shifts in snowfall, earlier snowmelt in spring, and delayed snowfall in autumn. Although arctic and alpine environments are both characterized by short growing seasons, they differ in fundamental ways that will affect their responses to changing seasonality. We compare meteorological data from sixteen arctic and alpine sites and biological data from two arctic and two alpine sites. We propose that although alpine and arctic ecosystems appear similar under historical climate conditions, especially during the growing season, winter conditions and climate change will result in divergent responses. Biotic responses to changing seasonality will affect belowground and aboveground community composition, trophic dynamics, and the functioning of these ecosystems, including net carbon balance.

  15. New homogenized daily lake surface water temperature data of three decades from multiple sensors confirm warming of large sub-alpine lake Garda

    NASA Astrophysics Data System (ADS)

    Pareeth, Sajid; Salmaso, Nico; Adrian, Rita; Neteler, Markus

    2016-04-01

    Availability of remotely sensed multi-spectral images from the early eighties covering three decades of voluminous data could help researchers to study the change dynamics in bio-physical characteristics of land and water. However it is very important to homogenize these data originating from multiple sources which follow different standards and quality. In this study, we explored the thermal dynamics of a large sub-alpine lake Garda over last twentyeight years (1986 - 2014) using Lake Surface Water Temperature (LSWT) derived from the thermal bands of moderate resolution sensors - AVHRR/2, AVHRR/3, ATSR1, ATSR2, A(A)TSR and MODIS aboard multiple satellites. We developed a homogenized daily LSWT dataset (12:00 P.M) at 1km spatial resolution combining the data from these sensors using split window technique and performing an acquisition time correction. The gaps in the temporal database due to clouds were filled by applying Harmonic ANalysis of Time Series (HANTS). The results show high correlation (R2 > 90) between satellite derived LSWT (taken into account both individual sensors and the combined data) and the in-situ data. The time correction enable us to perform a trend analysis on unified datasets corrected for its acquisition times. The trend analysis using non-parametric tests shows significant warming in annual trend at the rate of 0.01K yr-1 (p<0.05), while in summer the increasing trend is 0.02K yr-1(p<0.1). The results are in line with similar findings on warming of Alpine lakes. Moreover, the advantage of the spatial coverage at 1 km resolution we are able to characterize the thermal dynamics of the lake Garda at multiple locations of this large lake.

  16. Seasonal changes in CH4 emissions from an alpine reservoir, Lake Klöntal, Switzerland

    NASA Astrophysics Data System (ADS)

    Sollberger, S.; Eugster, W.; Schubert, C.; Wehrli, B.

    2012-04-01

    Atmospheric methane (CH4) concentration doubled since the pre-industrialized era and its potential as a greenhouse gas is 25 higher than CO2 over a 100-year horizon. Recent studies showed an important contribution of inland waters, including hydropower reservoirs, to the global CH4 cycle. However, the large seasonal and latitudinal variability of emissions reported in the literature highlights the necessity for a better understanding of CH4 emission mechanisms. The aim of this study was to investigate physical factors (water level and temperature) that trigger the seasonal pattern of CH4 emissions in a Swiss alpine reservoir, Lake Klöntal, using multiple methods. Atmospheric CH4 flux was measured using a fast methane analyzer (FMA, Los Gatos Research) and an eddy covariance tower set on a floating platform from April to December 2011 (before ice sets). Emissions were also measured monthly via chambers and calculated from surface water concentrations using Henry's law. Methane ebullition was examined over the lake surface of 5 km2 using a split-beam echosounder. Typical daily variations of CH4 were measured with the eddy covariance setup within the range of 0.23 and 7.4 mg CH4 m-2 d-1 (95% confidence interval) and were mainly related to temperature and solar radiation variability. The seasonal trend shows that average fluxes increase from 3.0 (April) to 3.7 mg CH4 m-2 d-1 in November. Much larger fluctuations can be observed in comparison to the chamber results where the emissions typically increase throughout the day. Furthermore, highest chamber fluxes were measured in July and October, which does not correspond with the FMA results (November). This inconsistency is also observed in the flux estimates calculated from surface concentrations of which the highest fluxes were in September. Ebullition was only observed (Jul., Sep. and Nov.) in a very shallow area where it was not possible to use the echosounder. Hence, our measurements may slightly underestimate the

  17. Compound-Specific Stable Isotopes of Organic Compounds From Lake Sediments Track Recent Environmental Changes in an Alpine Ecosystem, Rocky Mountain National Park, Colorado (United States of America)

    NASA Astrophysics Data System (ADS)

    Enders, S. K.; Pagani, M.; Pantoja, S.; Baron, J. S.; Wolfe, A. P.; Pedentchouk, N.; Nuñez, L.

    2007-12-01

    Sediments from high altitude lakes in the North American Cordillera reveal rapid changes in both the composition of diatom communities and bulk organic δ15N over the past c. 60 years. In this study, compound- specific nitrogen, carbon, and hydrogen isotope records from Sky Pond, an alpine lake in Rocky Mountain National Park (Colorado, United States of America), were used to identify the factors contributing to ecological change. Our results from the nitrogen isotopic compositions of purified algal chlorins indicate that the magnitude of isotopic change is larger than implied from bulk organic δ15N, and support a substantial shift in nitrogen (N)-cycling in the region. Temporal changes in the growth characteristics of lichen surrounding Sky Pond, as well as a -60‰ excursion in δD values of algal-derived palmitic acid, are coincident with changes in N-cycling, indicating alterations in catchment hydrology and nutrient delivery. The confluence of these trends is attributed to an increase in anthropogenic N deposition caused by both expansion anthropogenic influences and temporal changes in regional hydrology associated with snow, glacier, and permafrost melt.

  18. Where have all the females gone? Male biased sex-ratio in Arctodiaptomus alpinus (Imhof, 1885) in alpine lakes

    NASA Astrophysics Data System (ADS)

    Žibrat, U.; Brancelj, A.

    2009-04-01

    In populations with both males and females sex-ratio is one of the driving forces of population dynamics. It influences fecundity, inbreeding and social interactions. Sex-ratio is affected by several biotic and abiotic factors, either by selective killing of one sex or by inducing migrations. In alpine lakes of Triglav National Park, Slovenia, an extremely male biased sex-ratio in Arctodiaptomus alpinus (Imhof, 1885) was regularly observed since 1992. We analysed population dynamics and sex-ratio of A. alpinus in three alpine lakes (Jezero v Ledvicah, Rjavo jezero and Zgornje Kriško jezero) from Triglav National Park in Slovenia. In addition to seasonal dynamics we also researched long-term changes in sex-ratio (in a period of 11 years from autumn samples) as a result of increased air-temperature, and zooplankton diurnal vertical migrations. Adults of both sexes were found to appear at the same time in the water collumn with males prevailing throughout the season. A similar trend was found in copepodites CV. The percent of adult females began increasing in late summer, when there were no more copepodites and recrutation from copepodites CV to adults stopped, while male mortality increased. All cohorts of A. alpinus were found to perform diurnal vertical migrations. Both adult and CV females remained close to the bottom during the day and migrated vertically during the night. Results of the long-term study show no changes in sex-ratio in autumn.

  19. 20th century acidification and warming as recorded in two alpine lakes in the Tatra Mountains (South Poland, Europe).

    PubMed

    Gasiorowski, Michał; Sienkiewicz, Elwira

    2010-02-01

    Sediment profiles of two alpine lakes located in the Tatra Mountains, the Toporowy Staw Nizni (TSN) and the Zielony Staw Gasienicowy (ZSG), were studied for their chronology, lithology, diatom and cladoceran remains. The sediment sequences, 50cm long from TSN and 30cm long from ZSG, were deposited during the last 1000 and 300 years, respectively. Vertical changes in lithology, diatom and Cladocera allow the reconstruction of three periods in the lakes' evolution: mild climatic conditions during Medieval Warm Period (MWP, only in TSN), severe conditions between the end of 14th and 19th centuries, identified as the Little Ice Age (LIA), and 20th century warming. The LIA was recorded in the sediments of both lakes in the form of intensified erosion and lower lake ecosystem productivity, as indicated by organic matter lower content, changes in diatom species composition, and decline in Daphnia. The 20th century was a time of acidification in both lakes. The scale of acidification was assessed based on the decline in diatom-inferred pH (DI-pH). DI-pH dropped by 1.2 pH units during the last century in TSN and by 0.4 pH unit in ZSG. The decline of DI-pH was noted in both lakes, but its intensity was clearly higher in TSN due to the lower acid neutralisation capacity (ANC) of this lake. The lower pH during the final decades of the 20th century was lethal to some water organisms while attracting others, such as Daphnia. The Daphnia population increased after the pH drop, probably due to the high food flexibility of this genus. A similar increase was not observed in ZSG, where planktonivorous fishes were introduced in the 1940s, which effectively limited the crustacean plankton density. PMID:19896170

  20. Increased accuracy of species lists developed for alpine lakes using morphology and cytochrome oxidase I for identification of specimens.

    PubMed

    Deiner, Kristy; Knapp, Roland A; Boiano, Daniel M; May, Bernie

    2013-09-01

    The first step in many community ecology studies is to produce a species list from a sample of individuals. Community ecologists now have two viable ways of producing a species list: morphological and barcode identification. In this study, we compared the taxonomic resolution gained by a combined use of both methods and tested whether a change in taxonomic resolution significantly impacted richness estimates for benthic macroinvertebrates sampled from ten lakes in Sequoia National Park, USA. Across all lakes, 77 unique taxa were identified and 42% (32) were reliably identified to species using both barcode and morphological identification. Of the 32 identified to species, 63% (20) were identified solely by comparing the barcode sequence from cytochrome oxidase I to the Barcode of Life reference library. The increased resolution using a combined identification approach compared to identifications based solely on morphology resulted in a significant increase in estimated richness within a lake at the order, family, genus and species levels of taxonomy (P < 0.05). Additionally, young or damaged individuals that could not be identified using morphology were identified using their COI sequences to the genus or species level on average 75% of the time. Our results demonstrate that a combined identification approach improves accuracy of benthic macroinvertebrate species lists in alpine lakes and subsequent estimates of richness. We encourage the use of barcodes for identification purposes and specifically when morphology is insufficient, as in the case of damaged and early life stage specimens of benthic macroinvertebrates. PMID:23773698

  1. Historical deposition of persistent organic pollutants in Lake Victoria and two alpine equatorial lakes from East Africa: Insights into atmospheric deposition from sedimentation profiles.

    PubMed

    Arinaitwe, Kenneth; Rose, Neil L; Muir, Derek C G; Kiremire, Bernard T; Balirwa, John S; Teixeira, Camilla

    2016-02-01

    Information on historical deposition of persistent organic pollutants (POPs) for African lakes is very limited. We investigated historical deposition trends and sources of POPs in sediment cores from Lakes Victoria (SC1), Bujuku (Buju2) and Mahoma (Maho2). The latter two lakes are situated in the Rwenzori mountain range in western Uganda. SC1 was taken from a central depositional area within the Ugandan part of the lake. Profiles in Buju2 and Maho2 were used as a reference for historical atmospheric deposition. For the post-1940 sediment deposits in SC1, average focusing factor-adjusted fluxes (FFFs) of ΣDDTs, polychlorinated biphenyls (ΣPCBs), hexachlorocyclohexanes (ΣHCHs) and chlordanes (ΣCHLs) were 390, 230, 210 and 120 ng m(-2) yr(-1). Higher fluxes of ΣDDTs, ΣPCBs, and ΣCHLs were observed in Buju2 and Maho2. The average FFF of HCB in Buju2 was the highest while the values for Maho2 and SC1 were similar. The endosulfan FFFs in SC1 were lower than in the alpine lake cores. Generally, Buju2 was a better reference for historical atmospheric deposition of POPs than Maho2 probably due to distortion of the latter's profile by Lake Mahoma's forested catchment. Profiles of p,p'-DDE, ΣCHLs and HCB in SC1 were consistent with atmospheric deposition while profiles of PCBs and HCHs were indicative of particle-bound loadings from additional sources. Profiles of endosulfans, DDTs, and chlordanes were consistent with influence of other factors such as anoxia, and dilution. Further studies of spatial resolution of historical deposition, especially in near-shore deposition areas of the lake are recommended. PMID:26539705

  2. Numerical simulation of local atmospheric circulations in the pre-Alpine area between Lake Garda and Verona

    NASA Astrophysics Data System (ADS)

    Laiti, L.; Serafin, S.; Zardi, D.

    2010-09-01

    The pre-Alpine area between Lake Garda and Verona displays a very complex and heterogeneous territory, allowing the development of several interacting systems of thermally driven local winds, the major being the lake/land breeze system on the coasts of Lake Garda and the up/down-valley wind system between the plain and the river Adige Valley. In order to investigate the local wind patterns, a series of nested numerical simulations with a horizontal resolution of 500 m were carried out using the ARPS 5.2.9 model (Xue et al. 2000, 2001), considering a fair weather day suitable for a clear development of the expected circulations (15th July 2003). The simulated wind speed and direction, pressure, temperature and water vapour mixing ratio were compared to synoptic scale meteorological charts, to vertical profiles from radiosoundings taken at the major sounding stations of the alpine region and to local scale measurements performed at the surface station of Dolcè (at the inlet of the Adige Valley). Numerical results at all scales were found to be in very good agreement with the available sets of meteorological observations. The analysis of the diurnal evolution of the 3D fields of temperature, moisture content, wind and turbulent kinetic energy allowed the identification of a very shallow and clearly defined breeze front of cold and humid air moving from off-shore towards the Lake Garda coast, from the late morning (10:00 LST) until the evening (20:00 LST). The diurnal up-valley breeze was also well reproduced: the valley atmosphere displays a thick mixed layer dominated by shallow turbulent convection between 11:00 LST and 21:00 LST. Lateral slope winds were also recognized, as they created cross-valley convective cells. While no clear evidence of a nocturnal land breeze was found in the simulations, the nocturnal down-valley wind in the Adige Valley was clearly reproduced. Finally, a scalar transport equation was added to the ARPS model in order to simulate transport

  3. Assessing the response of Emerald Lake, an alpine watershed in Sequoia National Park, California, to acidification during snowmelt by using a simple hydrochemical model. Final report

    SciTech Connect

    Hooper, R.P.; West, C.T.; Peters, N.E.

    1990-08-01

    The authors constructed a simple, process-oriented model, called the Alpine Lake Forecaster (ALF), using data collected during the Integrated Watershed Study at Emerald Lake, Sequoia National Park, CA. The model was designed to answer questions concerning the impact of acid deposition on high-elevation watersheds in the Sierra Nevada, CA. ALF is able to capture the basic solute patterns in stream water during snowmelt in this alpine catchment where ground water is a minor contributor to stream flow. It includes an empirical representation of primary mineral weathering as the only alkalinity-generating mechanism. Hydrologic and chemical data from a heavy snow year were used to calibrate the model. Watershed processes during a light snow year appeared to be different from the calibration year. The model forecast concludes that stream and lake water are most likely to experience a loss of ANC and depression in pH during spring rain storms that occur during the snowmelt dilution phase.

  4. Benthic Diatoms of an Alpine Stream/Lake Network in Switzerland

    NASA Astrophysics Data System (ADS)

    Rueegg, J.; Robinson, C. T.; Kawecka, B.

    2005-05-01

    We compared the benthic diatom composition of lakes, and lake inlet and outlet streams in a high elevation catchment (~2600 m a.s.l.). The catchment was separated in a southern and northern basin with different water sources. Streams in both basins flowed through a series of small lakes before converging into a lake with a primary outlet. The south basin had lower water temperatures and 2× higher nitrate-N levels (up to 300 μg/L) while the north basin had 2-4× higher levels of particulate-P, particulate-N, and particulate organic matter. 143 and 109 diatom species was identified in streams and lakes, respectively, with a similar number of species found in each basin. PCA showed a clear separation between basins. Of the 10 most common species, Psammothidium helveticum, Achnanthes helvetica var. minor, Achnanthes marginulata, Achnanthes subatomoides, and Diatoma mesodon were more abundant in south basin, whereas Achnanthidium minutissimum, Aulacoseira alpigena and Luticola goeppertiana were more abundant in the north. In general, lake outlet assemblages were similar to respective downstream lake inlet assemblages. Composition shifted along each basins longitudinal flow path. The spatial patterns in species composition reflected the hierarchical interaction of landscape features (geology, hydrology) on longitudinal gradients (lake position) in the stream/lake network.

  5. Effects of Short-Term Warming and Altered Precipitation on Soil Microbial Communities in Alpine Grassland of the Tibetan Plateau

    PubMed Central

    Zhang, Kaoping; Shi, Yu; Jing, Xin; He, Jin-Sheng; Sun, Ruibo; Yang, Yunfeng; Shade, Ashley; Chu, Haiyan

    2016-01-01

    Soil microbial communities are influenced by climate change drivers such as warming and altered precipitation. These changes create abiotic stresses, including desiccation and nutrient limitation, which act on microbes. However, our understanding of the responses of microbial communities to co-occurring climate change drivers is limited. We surveyed soil bacterial and fungal diversity and composition after a 1-year warming and altered precipitation manipulation in the Tibetan plateau alpine grassland. In isolation, warming and decreased precipitation treatments each had no significant effects on soil bacterial community structure; however, in combination of both treatments altered bacterial community structure (p = 0.03). The main effect of altered precipitation specifically impacted the relative abundances of Bacteroidetes and Gammaproteobacteria compared to the control, while the main effect of warming impacted the relative abundance of Betaproteobacteria. In contrast, the fungal community had no significant response to the treatments after 1-year. Using structural equation modeling (SEM), we found bacterial community composition was positively related to soil moisture. Our results indicate that short-term climate change could cause changes in soil bacterial community through taxonomic shifts. Our work provides new insights into immediate soil microbial responses to short-term stressors acting on an ecosystem that is particularly sensitive to global climate change. PMID:27446064

  6. Effects of Short-Term Warming and Altered Precipitation on Soil Microbial Communities in Alpine Grassland of the Tibetan Plateau.

    PubMed

    Zhang, Kaoping; Shi, Yu; Jing, Xin; He, Jin-Sheng; Sun, Ruibo; Yang, Yunfeng; Shade, Ashley; Chu, Haiyan

    2016-01-01

    Soil microbial communities are influenced by climate change drivers such as warming and altered precipitation. These changes create abiotic stresses, including desiccation and nutrient limitation, which act on microbes. However, our understanding of the responses of microbial communities to co-occurring climate change drivers is limited. We surveyed soil bacterial and fungal diversity and composition after a 1-year warming and altered precipitation manipulation in the Tibetan plateau alpine grassland. In isolation, warming and decreased precipitation treatments each had no significant effects on soil bacterial community structure; however, in combination of both treatments altered bacterial community structure (p = 0.03). The main effect of altered precipitation specifically impacted the relative abundances of Bacteroidetes and Gammaproteobacteria compared to the control, while the main effect of warming impacted the relative abundance of Betaproteobacteria. In contrast, the fungal community had no significant response to the treatments after 1-year. Using structural equation modeling (SEM), we found bacterial community composition was positively related to soil moisture. Our results indicate that short-term climate change could cause changes in soil bacterial community through taxonomic shifts. Our work provides new insights into immediate soil microbial responses to short-term stressors acting on an ecosystem that is particularly sensitive to global climate change. PMID:27446064

  7. Submicron Organic Matter in a Peri-alpine, Ultra-oligotrphic Lake

    SciTech Connect

    Chanudet,V.; Filella, M.

    2007-01-01

    Combining organic carbon (OC) measurements with the classic MBTH (3-methyl-2-benzothiazolinone hydrochloride) method for carbohydrate determination and a new voltammetric method for the determination of refractory organic matter (ROM) made it possible, for the first time, to quantify the types, sources and fate of submicron organic matter present in an ultra-oligotrophic lake (Lake Brienz, Switzerland). The lake is extremely rich in suspended glacial flour in summer (glacier melting season). Measurements were taken from June 2004 to October 2005 from 1.2 {mu}m filtered samples. OC concentration remained extremely low throughout the year (below 1 mg C L{sup -1}). MBTH carbohydrate concentration was very low in the lake (0.06-0.43 mg C L{sup -1}) and in the two tributary rivers (0.06-0.25 mg C L{sup -1}). Lake carbohydrate concentration only correlated with phytoplanktonic biomass at the onset of the productivity period. The results suggest that differences in MBTH concentration may sometimes reflect differences in the nature of the carbohydrates rather than differences in carbon concentration. Extensive fibril formation was evidenced by transmission electron microscopy (TEM) observations. ROM concentration in the lake was also very low (0.1-0.2 mg C L{sup -1}). Significant variation in ROM riverine input was due to either annual occurrences (snow melting) or irregular episodes (floods). Melting snow was responsible for about 30% of the lake's annual ROM input. One box mass balance calculations showed that about 25% of ROM was lost within the lake. Evidence gleaned from TEM and STXM (scanning transmission X-ray microscopy) observations clearly indicates that this is mainly caused by ROM sedimentation after association with inorganic colloids.

  8. Experimental soil warming alters the sources of DOM in alpine treeline soils

    NASA Astrophysics Data System (ADS)

    Hagedorn, Frank; Dawes, Melissa; Rixen, Christian

    2013-04-01

    The aim of our study was to quantify the sources of DOM in alpine treeline soils and to estimate how soil warming affects DOM generation. In order to track new carbon through the plant and soil system, we made use of a 9-year CO2 enrichment experiment, in which the added CO2 carried another 13C signature than normal air and provided a 13C-label for new plant-derived C. The CO2 enrichment study was combined with a six year long experimental soil warming by 4°C with heating cables on the soil surface. This approach gave insights into the effects of soil warming on the production of DOM from 'new' (root and litter) and old (SOM) sources. Our 13C tracing showed that significant amounts of recent assimilates were allocated to the belowground as soil-respired CO2 consisted approximately to 60% of new, less than 9 year-old C. In DOM of the organic layer at 5 cm depth, however, the contribution of new plant-derived C was less than 30%; in mineral soil's DOM the 13C label was even not detectable. The 13C-based mean ages of DOC in the Oa horizon were 22 to 30 years and four times greater than that of the litter layer. Therefore, DOM in the Oa horizon was dominated by 'older' C, while new C from throughfall, fresh litter, and root exudates contributed little to Oa-DOM. We attribute the small leaching rates of new DOM to (1) low input of fresh organic matter as compared to the total soil organic matter in alpine ecosystems; (2) rapid biodegradation of labile new DOM such as root exudates. Experimental soil warming increased soil CO2 effluxes instantaneously and continuously for six years (+45%; +120 g C m y-1). In contrast, DOM leaching showed only a negligible initial response (<+10%), indicating that DOM production is less temperature sensitive than soil respiration. One reason might be that the production and consumption of DOM were tightly balanced, resulting in small net changes in DOM leaching. Another explanation was given by the 13C tracing, showing that soil warming

  9. Forest Gaps Alter the Total Phenol Dynamics in Decomposing Litter in an Alpine Fir Forest

    PubMed Central

    Li, Han; Xu, Liya; Wu, Fuzhong; Yang, Wanqin; Ni, Xiangyin; He, Jie; Tan, Bo; Hu, Yi

    2016-01-01

    The total phenol content in decomposing litter not only acts as a crucial litter quality indicator, but is also closely related to litter humification due to its tight absorption to clay particles. However, limited attention has been focused on the total phenol dynamics in foliar litter in relation to forest gaps. Here, the foliar litter of six representative tree species was incubated on the forest floor from the gap center to the closed canopy of an alpine Minjiang fir (Abies faxoniana) forest in the upper reaches of the Yangtze River and eastern Tibetan Plateau. The dynamics of total phenol concentration in the incubated litter was measured from November 2012 to October 2014. Over two-year incubation, 78.22% to 94.06% of total phenols were lost from the foliar litter, but 52.08% to 86.41% of this occurred in the first year. Forest gaps accelerated the loss of total phenols in the foliar litter in the winter, although they inhibited the loss of total phenols during the growing season in the first year. In comparison with the effects of forest gaps, the variations of litter quality among different species were much stronger on the dynamics of total phenols in the second year. Overall, the loss of total phenols in the foliar litter was slightly higher in both the canopy gap and the expanded gap than in the gap center and under the closed canopy. The results suggest that the predicted decline in snow cover resulting from winter warming or vanishing gaps caused by forest regeneration will retard the loss of total phenol content in the foliar litter of alpine forest ecosystems, especially in the first decomposition year. PMID:26849120

  10. Forest Gaps Alter the Total Phenol Dynamics in Decomposing Litter in an Alpine Fir Forest.

    PubMed

    Li, Han; Xu, Liya; Wu, Fuzhong; Yang, Wanqin; Ni, Xiangyin; He, Jie; Tan, Bo; Hu, Yi

    2016-01-01

    The total phenol content in decomposing litter not only acts as a crucial litter quality indicator, but is also closely related to litter humification due to its tight absorption to clay particles. However, limited attention has been focused on the total phenol dynamics in foliar litter in relation to forest gaps. Here, the foliar litter of six representative tree species was incubated on the forest floor from the gap center to the closed canopy of an alpine Minjiang fir (Abies faxoniana) forest in the upper reaches of the Yangtze River and eastern Tibetan Plateau. The dynamics of total phenol concentration in the incubated litter was measured from November 2012 to October 2014. Over two-year incubation, 78.22% to 94.06% of total phenols were lost from the foliar litter, but 52.08% to 86.41% of this occurred in the first year. Forest gaps accelerated the loss of total phenols in the foliar litter in the winter, although they inhibited the loss of total phenols during the growing season in the first year. In comparison with the effects of forest gaps, the variations of litter quality among different species were much stronger on the dynamics of total phenols in the second year. Overall, the loss of total phenols in the foliar litter was slightly higher in both the canopy gap and the expanded gap than in the gap center and under the closed canopy. The results suggest that the predicted decline in snow cover resulting from winter warming or vanishing gaps caused by forest regeneration will retard the loss of total phenol content in the foliar litter of alpine forest ecosystems, especially in the first decomposition year. PMID:26849120

  11. Comparison of optical properties of chromophoric dissolved organic matter (CDOM) in alpine lakes above or below the tree line: insights into sources of CDOM.

    PubMed

    Su, Yaling; Chen, Feizhou; Liu, Zhengwen

    2015-05-01

    Here we investigated absorption and fluorescence properties of chromophoric dissolved organic matter (CDOM) in 15 alpine lakes located below or above the tree line to determine its source and composition. The results indicate that the concentrations of CDOM in below-tree-line lakes are significantly higher than in above-tree-line lakes, as evidenced from the absorption coefficients of a250 and a365. The intensities of the protein-like and humic-like fluorescence in below-tree-line lakes are higher than in above-tree-line lakes as well. Three fluorescent components were identified using parallel factor analysis (PARAFAC) modelling. Component 1 is probably associated with biological degradation of terrestrial humic component. The terrestrial humic-like component 2 is only found in below-tree-line lakes. The protein-like or phenolic component 3 is dominant in above-tree-line lakes, which is probably more derived from autochthonous origin. In this study, (1) higher a250/a365 and S275-295 values indicate smaller molecular weights of CDOM in above-tree-line lakes than in below-tree-line lakes, and smaller molecular weights at the surface than at 2.0 m depth; (2) SUVA254 and FI255 results provide evidence of lower percent aromaticity of CDOM in above-tree-line lakes; and (3) FI310 and FI370 suggest a strong allochthonous origin at the surface in below-tree-line lakes, and more contribution from autochthonous biological and aquatic bacterial origin in above-tree-line lakes. PMID:25694220

  12. Global warming alters carbon sink and source situation of the Tibetan lakes

    NASA Astrophysics Data System (ADS)

    Jiang, H.; Ni, Q.; Yang, J.; Liu, W.

    2015-12-01

    Global warming would accelerate glacier retreat and permafrost degeneration on the Tibetan Plateau. The carbon stored in permafrost would be released to nearby lakes. However, little is known about how the carbon sink and source situation could be altered and what role the microbial community could play in Tibetan lakes in response to global warming. To fill this knowledge gap, six lakes (Erhai Lake, Qinghai Lake, Tuosu Lake, Gahai Lake, Xiaochaidan Lake and Lake Chaka) on the Tibetan Plateau were studied. In order to compare the seasonal variations in geochemistry and microbial communities, two sampling cruises were performed (May and July of 2015, corresponding to dry and wet seasons, respectively). For each lake, salinity, pH, dissolved organic carbon (DOC), total nitrogen (TN), and chlorophyll were measured for water samples, and salinity and total organic carbon (TOC) were measured for sediments. Chamber-based greenhouse gas flux measurement were performed on the surface of each lake. Microbial communities were analyzed by using MiSeq sequencing technique. The results showed that in response to seasonal variation (from dry to set season), lake surface increased by 5-20% (calculated on the basis of satellite data) and salinity decreased by 4-30% for the studied lakes, suggesting the studied lakes were diluted by precipitations. The DOC contents of the lake waters were almost stable for the studied lakes, whereas TN increased by more than 70% for the lakes with salinity less than 100g/L. In the meanwhile, chlorophyll content increased by more than 180% for lakes with low salinities (Erhai Lake, Qinghai Lake, and Tuosu Lake) and decreased by 17-94% for lakes with high salinities (Gahai Lake, Xiaoxhaidan Lake, and Lake Chaka. This indicated that desalination (precipitation plus glacier melt) would increase carbon fixation potential in Tibetan lakes. Microbial community analyses showed that microbial diversity increased in response to desalination. All in all

  13. The changing microstructural arrangement of graphite during deformation and hydrothermal alteration of amphibolite-facies mylonite, Alpine Fault, New Zealand.

    NASA Astrophysics Data System (ADS)

    Kirilova, M.; Toy, V.; Timms, N.; Craw, D.; Little, T. A.; Halfpenny, A.; Beyssac, O.

    2015-12-01

    Graphitisation in a convergent plate boundary setting, such as the Alpine Fault, New Zealand, is associated both with fault weakening and orogenic gold mineralisation. Previously, these processes have been investigated in rocks that experienced mineralisation at maximum of greenschist-facies conditions. However, metals are most mobile at upper greenschist- to amphibolite-facies. We examine the microstructural record of mobilisation of graphite at these conditions due to dislocation and diffusion creep in the Alpine Fault zone and as a function of varying shear strain magnitude. We have mapped graphite distribution across a strain gradient in samples, recovered from Deep Fault Drilling Project (DFDP) boreholes, by using reflected light and scanning electron microscopy. Raman spectrometry was used to determine the degree of maturity of the carbonaceous material. In the schists and protomylonites, graphite occurs as very fine (1-5μm), dusty grains, dispersed as inclusions in the main mineral phases (quartz, anorthite, muscovite, biotite). Further into the mylonite zone, the modal proportion of graphite increases and it forms clusters and trains, aligned with the foliation. In the brittlely-deformed rocks (cataclasites and gouges on or near the fault principal slip zone) graphite is most abundant (<50%), occurring as clusters and shear plane parallel trains. We infer shear deformation under both ductile and brittle conditions concentrates the graphite. Independent evidence demonstrates fluid transport and consequent alteration was most important in the brittlely deformed rocks (Sutherland et al., 2012, Geology 40, 1143; Schleicher et al., in press. N.Z.J.Geol&Geophys). We thus infer hydrothermal enrichment caused graphite remobilization, re-deposition, and enrichment in structurally controlled microstructural sites. We will discuss implications of these microstructural and mineralogical changes for strain localisation and deformation-induced permeability.

  14. Direct versus indirect climate controls on Holocene diatom assemblages in a sub-tropical deep, alpine lake (Lugu Hu, Yunnan, SW China)

    NASA Astrophysics Data System (ADS)

    Wang, Qian; Yang, Xiangdong; Anderson, Nicholas John; Dong, Xuhui

    2016-07-01

    The reconstruction of Holocene environmental changes in lakes on the plateau region of southwest China provides an understanding of how these ecosystems may respond to climate change. Fossil diatom assemblages were investigated from an 11,000-year lake sediment core from a deep, alpine lake (Lugu Hu) in southwest China, an area strongly influenced by the southwest (or the Indian) summer monsoon. Changes in diatom assemblage composition, notably the abundance of the two dominant planktonic species, Cyclotella rhomboideo-elliptica and Cyclostephanos dubius, reflect the effects of climate variability on nutrient dynamics, mediated via thermal stratification (internal nutrient cycling) and catchment-vegetation processes. Statistical analyses of the climate-diatom interactions highlight the strong effect of changing orbitally-induced solar radiation during the Holocene, presumably via its effect on the lake's thermal budget. In a partial redundancy analysis, climate (solar insolation) and proxies reflecting catchment process (pollen percentages, C/N ratio) were the most important drivers of diatom ecological change, showing the strong effects of climate-catchment-vegetation interactions on lake functioning. This diatom record reflects long-term ontogeny of the lake-catchment ecosystem and suggests that climatic changes (both temperature and precipitation) impact lake ecology indirectly through shifts in thermal stratification and catchment nutrient exports.

  15. Non-intrusive characterization methods for wastewater-affected groundwater plumes discharging to an alpine lake.

    PubMed

    Roy, James W; Robillard, Jasen M; Watson, Susan B; Hayashi, Masaki

    2009-02-01

    Streams and lakes in rocky environments are especially susceptible to nutrient loading from wastewater-affected groundwater plumes. However, the use of invasive techniques such as drilling wells, installing piezometers or seepage meters, to detect and characterize these plumes can be prohibitive. In this work, we report on the use of four non-intrusive methods for this purpose at a site in the Rocky Mountains. The methods included non-invasive geophysical surveys of subsurface electrical conductivity (EC), in-situ EC measurement of discharging groundwater at the lake-sediment interface, shoreline water sampling and nutrient analysis, and shoreline periphyton sampling and analysis of biomass and taxa relative abundance. The geophysical surveys were able to detect and delineate two high-EC plumes, with capacitively coupled ERI (OhmMapper) providing detailed two-dimensional images. In situ measurements at the suspected discharge locations confirmed the presence of high-EC water in the two plumes and corroborated their spatial extent. The nutrient and periphyton results showed that only one of the two high-EC plumes posed a current eutrophication threat, with elevated nitrogen and phosphorus levels, high localized periphyton biomass and major shifts in taxonomic composition to taxa that are commonly associated with anthropogenic nutrient loading. This study highlights the need to use non-intrusive methods in combination, with geophysical and water EC-based methods used for initial detection of wastewater-affected groundwater plumes, and nutrient or periphyton sampling used to characterize their ecological effects. PMID:18253851

  16. Holocene Asian monsoon evolution revealed by a pollen record from an alpine lake on the southeastern margin of the Qinghai-Tibetan Plateau, China

    NASA Astrophysics Data System (ADS)

    Zhang, Enlou; Wang, Yongbo; Sun, Weiwei; Shen, Ji

    2016-02-01

    We present the results of pollen analyses from a 1105 cm long sediment core from Wuxu Lake in southwestern China, which depict the variations of the East Asian winter monsoon (EAWM) and the Indian summer monsoon (ISM) during the last 12.3 ka. During the period of 12.3 to 11.3 cal ka BP, the dominance of Betula forest and open alpine shrub and meadow around Wuxu Lake indicates a climate with relatively cold winters and dry summers, corresponding to the Younger Dryas event. Between 11.3 and 10.4 cal ka BP, further expansion of Betula forest and the retreat of alpine shrubs and meadows reflect a greater seasonality with cold winters and gradually increasing summer precipitation. From 10.4 to 4.9 cal ka BP, the dense forest understory, together with the gradual decrease in Betula forest and increase in Tsuga forest, suggest that the winters became warmer and summer precipitation was at a maximum, corresponding to the Holocene climatic optimum. Between 4.9 and 2.6 cal ka BP, Tsuga forest and alpine shrubs and meadows expanded significantly, reflecting relatively warm winters and decreased summer precipitation. Since 2.6 cal ka BP, reforestation around Wuxu Lake indicates a renewed humid period in the late Holocene; however, the vegetation in the catchment may also have been affected by grazing activity during this period. The results of our study are generally consistent with previous findings; however, the timing and duration of the Holocene climatic optimum from different records are inconsistent, reflecting real contrast in local rainfall response to the ISM. Overall, the EAWM is broadly in-phase with the ISM on the orbital timescale, and both monsoons exhibit a trend of decreasing strength from the early to late Holocene, reflecting the interplay of solar insolation receipt between the winter and summer seasons and El Niño-Southern Oscillation strength in the tropical Pacific.

  17. Holocene Asian monsoon evolution revealed by a pollen record from an alpine lake on the southeastern margin of the Qinghai-Tibetan Plateau, China

    NASA Astrophysics Data System (ADS)

    Zhang, E.; Wang, Y.; Sun, W.; Shen, J.

    2015-10-01

    We present the results of pollen analyses from a 1105-cm-long sediment core from Wuxu Lake in southwestern China, which depict the variations of the East Asian winter monsoon (EAWM) and the Indian summer monsoon (ISM) during the last 12.3 ka. During the period of 12.3 to 11.3 cal ka BP, the dominance of Betula forest and open alpine shrub and meadow around Wuxu Lake indicates a climate with relatively cold winters and dry summers, corresponding to the Younger Dryas event. Between 11.3 and 10.4 cal ka BP, further expansion of Betula forest and the retreat of alpine shrubs and meadows reflect a greater seasonality with cold winters and gradually increasing summer precipitation. From 10.4 to 4.9 cal ka BP, the dense forest understory, together with the gradual decrease in Betula forest and increase in Tsuga forest, suggest that the winters became warmer and summer precipitation was at a maximum, corresponding to the Holocene climatic optimum. Between 4.9 and 2.6 cal ka BP, Tsuga forest and alpine shrubs and meadows expanded significantly, reflecting relatively warm winters and decreased summer precipitation. Since 2.6 cal ka BP, reforestation around Wuxu Lake indicates a renewed strengthening of the ISM in the late Holocene; however, the vegetation in the catchment may also have been affected by grazing activity during this period. The results of our study are generally consistent with previous findings; however, the timing and duration of the Holocene climatic optimum from different records are inconsistent, reflecting real contrast in local rainfall response to the ISM. Overall, the EAWM is broadly in-phase with the ISM on the orbital timescale, and both monsoons exhibit a trend of decreasing strength from the early to late Holocene, reflecting the interplay of solar insolation receipt between the winter and summer seasons and El Niño Southern Oscillation strength in the tropical Pacific.

  18. Compound-specific stable isotopes of organic compounds from lake sediments track recent environmental changes in an alpine ecosystem, Rocky Mountain National Park, Colorado

    USGS Publications Warehouse

    Enders, S.K.; Pagani, M.; Pantoja, S.; Baron, J.S.; Wolfe, A.P.; Pedentchouk, N.; Nunez, L.

    2008-01-01

    Compound-specific nitrogen, carbon, and hydrogen isotope records from sediments of Sky Pond, an alpine lake in Rocky Mountain National Park (Colorado, United States of America), were used to evaluate factors contributing to changes in diatom assemblages and bulk organic nitrogen isotope records identified in lake sediments across Colorado, Wyoming, and southern Montana. Nitrogen isotopic records of purified algal chlorins indicate a substantial shift in nitrogen cycling in the region over the past ???60 yr. Temporal changes in the growth characteristics of algae, captured in carbon isotope records in and around Sky Pond, as well as a -60??? excursion in the hydrogen isotope composition of algal-derived palmitic acid, are coincident with changes in nitrogen cycling. The confluence of these trends is attributed to an increase in biologically available nitrogenous compounds caused by an expansion of anthropogenic influences and temporal changes in catchment hydrology and nutrient delivery associated with meltwater dynamics. ?? 2008, by the American Society of Limnology and Oceanography, Inc.

  19. Late Pleistocene and Holocene paleoclimate and alpine glacier fluctuations recorded by high-resolution grain-size data from an alpine lake sediment core, Wind River Range, Wyoming, USA

    NASA Astrophysics Data System (ADS)

    Thompson Davis, P.; Machalett, Björn; Gosse, John

    2013-04-01

    structural features similar to delta 18O records from deep-lake ostracods in southern Germany, the Greenland ice core record, and speleothems in China. Major increases in the 2 - 8 µm grain size fraction indicative of increased glacier rock flour production between the 257 and 466 cm core depths appear to be roughly correlative with the YD-Alleröd-Bölling-Meiendorf-Heinrich 1 climate events recognized in other terrestrial records and Northern Atlantic Ocean marine cores, but provide much higher resolution than most of those records from a climate-sensitive alpine region in North America.

  20. Chilling- and Freezing- Induced Alterations in Cytosine Methylation and Its Association with the Cold Tolerance of an Alpine Subnival Plant, Chorispora bungeana

    PubMed Central

    Song, Yuan; Liu, Lijun; Feng, Yanhao; Wei, Yunzhu; Yue, Xiule; He, Wenliang; Zhang, Hua; An, Lizhe

    2015-01-01

    Chilling (0–18°C) and freezing (<0°C) are two distinct types of cold stresses. Epigenetic regulation can play an important role in plant adaptation to abiotic stresses. However, it is not yet clear whether and how epigenetic modification (i.e., DNA methylation) mediates the adaptation to cold stresses in nature (e.g., in alpine regions). Especially, whether the adaptation to chilling and freezing is involved in differential epigenetic regulations in plants is largely unknown. Chorispora bungeana is an alpine subnival plant that is distributed in the freeze-thaw tundra in Asia, where chilling and freezing frequently fluctuate daily (24 h). To disentangle how C. bungeana copes with these intricate cold stresses through epigenetic modifications, plants of C. bungeana were treated at 4°C (chilling) and -4°C (freezing) over five periods of time (0–24 h). Methylation-sensitive amplified fragment-length polymorphism markers were used to investigate the variation in DNA methylation of C. bungeana in response to chilling and freezing. It was found that the alterations in DNA methylation of C. bungeana largely occurred over the period of chilling and freezing. Moreover, chilling and freezing appeared to gradually induce distinct DNA methylation variations, as the treatment went on (e.g., after 12 h). Forty-three cold-induced polymorphic fragments were randomly selected and further analyzed, and three of the cloned fragments were homologous to genes encoding alcohol dehydrogenase, UDP-glucosyltransferase and polygalacturonase-inhibiting protein. These candidate genes verified the existence of different expressive patterns between chilling and freezing. Our results showed that C. bungeana responded to cold stresses rapidly through the alterations of DNA methylation, and that chilling and freezing induced different DNA methylation changes. Therefore, we conclude that epigenetic modifications can potentially serve as a rapid and flexible mechanism for C. bungeana to

  1. Sustainable knowledge development across cultural boundaries: Experiences from the EU-project SILMAS (Toolbox for conflict solving instruments in Alpine Lake Management)

    NASA Astrophysics Data System (ADS)

    Fegerl, Michael; Wieden, Wilfried

    2013-04-01

    Increasingly people have to communicate knowledge across cultural and language boundaries. Even though recent technologies offer powerful communication facilities people often feel confronted with barriers which clearly reduce their chances of making their interaction a success. Concrete evidence concerning such problems derives from a number of projects, where generated knowledge often results in dead-end products. In the Alpine Space-project SILMAS (Sustainable Instruments for Lake Management in Alpine Space), in which both authors were involved, a special approach (syneris® ) was taken to avoid this problem and to manage project knowledge in sustainable form. Under this approach knowledge input and output are handled interactively: Relevant knowledge can be developed continuously and users can always access the latest state of expertise. Resort to the respective tools and procedures can also assist in closing knowledge gaps and in developing innovative responses to familiar or novel problems. This contribution intends to describe possible ways and means which have been found to increase the chances of success of knowledge communication across cultural boundaries. The process of trans-cultural discussions of experts to find a standardized solution is highlighted as well as the problem of dissemination of expert knowledge to variant stakeholders. Finally lessons learned are made accessible, where a main task lies in the creation of a tool box for conflict solving instruments, as a demonstrable result of the project and for the time thereafter. The interactive web-based toolbox enables lake managers to access best practice instruments in standardized, explicit and cross-linguistic form.

  2. Alpine Microbial Community Responses to Summer Warming

    NASA Astrophysics Data System (ADS)

    Osborne, B. B.; Baron, J.; Wallenstein, M. D.

    2011-12-01

    Remote alpine ecosystems of the western US are vulnerable to anthropogenic drivers of change. Atmospheric nitrogen (N) deposition and a changing climate introduce nutrients, alter hydrological processes, and expose soils to novel temperature regimes. We asked whether terrestrial microbes, specifically nitrifiers that may contribute to already high lake and stream NO3- concentrations, may be responding to changes in important controls of community development and activity associated with a changing climate, namely temperature and moisture. In August 2010 we sampled three soils from the Loch Vale Watershed in Rocky Mountain National Park which fell along a gradient of succession commonly represented in deglaciated alpine catchments. These included well-developed meadow soils, poorly vegetated talus substrate, and newly-exposed glacial outwash. Outwash, talus, and meadow samples were all N-rich and contained NH4-N concentrations ~7 times higher than NO3-N. Soils were incubated for 45 days at 2.5, 10, and 25oC and three moisture levels based on initial field conditions. Nitrifier concentrations were greatest in outwash, intermediate in talus, and lowest in meadow samples. Bacterial nitrifier abundance greatly surpassed archaeal nitrifier levels. Net nitrification was also greatest in outwash, followed by meadow and talus respectively. Moisture, rather than temperature, was a dominant control over both nitrifier abundance and activity. Linking the influence of temperature and moisture on alpine microbial communities will provide insight into control thresholds, optima, and synergistic interactions. This research is part of a larger study of controls on headwater stream and lake NO3-. Characterizing microbial NO3- production in the alpine will help us evaluate the importance of biological, as opposed to physical, sources of stream NO3-. It will also inform our ability to forecast and mitigate consequences of anthropogenic drivers of change on these systems.

  3. The Response of the Alpine Dwarf Shrub Salix herbacea to Altered Snowmelt Timing: Lessons from a Multi-Site Transplant Experiment.

    PubMed

    Sedlacek, Janosch; Wheeler, Julia A; Cortés, Andrés J; Bossdorf, Oliver; Hoch, Guenter; Lexer, Christian; Wipf, Sonja; Karrenberg, Sophie; van Kleunen, Mark; Rixen, Christian

    2015-01-01

    Climate change is altering spring snowmelt patterns in alpine and arctic ecosystems, and these changes may alter plant phenology, growth and reproduction. To predict how alpine plants respond to shifts in snowmelt timing, we need to understand trait plasticity, its effects on growth and reproduction, and the degree to which plants experience a home-site advantage. We tested how the common, long-lived dwarf shrub Salix herbacea responded to changing spring snowmelt time by reciprocally transplanting turfs of S. herbacea between early-exposure ridge and late-exposure snowbed microhabitats. After the transplant, we monitored phenological, morphological and fitness traits, as well as leaf damage, during two growing seasons. Salix herbacea leafed out earlier, but had a longer development time and produced smaller leaves on ridges relative to snowbeds. Longer phenological development times and smaller leaves were associated with reduced sexual reproduction on ridges. On snowbeds, larger leaves and intermediate development times were associated with increased clonal reproduction. Clonal and sexual reproduction showed no response to altered snowmelt time. We found no home-site advantage in terms of sexual and clonal reproduction. Leaf damage probability depended on snowmelt and thus exposure period, but had no short-term effect on fitness traits. We conclude that the studied populations of S. herbacea can respond to shifts in snowmelt by plastic changes in phenology and leaf size, while maintaining levels of clonal and sexual reproduction. The lack of a home-site advantage suggests that S. herbacea may not be adapted to different microhabitats. The studied populations are thus unlikely to react to climate change by rapid adaptation, but their responses will also not be constrained by small-scale local adaptation. In the short term, snowbed plants may persist due to high stem densities. However, in the long term, reduction in leaf size and flowering, a longer phenological

  4. Tracking the sediment imprint of floods (in pre-Alpine Lake Mondsee) by a combined catchment and in-lake monitoring system

    NASA Astrophysics Data System (ADS)

    Mueller, Philip; Kämpf, Lucas; Thoss, Heiko; Güntner, Andreas; Merz, Bruno; Brauer, Achim

    2014-05-01

    Lakes form ideal sediment traps in the landscape and continuously record land surface processes including extreme events. During floods, detrital sediment is transported via tributary streams and deposited at the lake floor as discrete layers, intercalated in autochthonous lake sediments. Lacustrine records of detrital layers are increasingly explored as flood archives for pre-instrumental periods. The annually laminated sediments of Lake Mondsee (486 m a.s.l., Upper Austria) contain a flood layer chronology over the past 7000 years with seasonal resolution. The interpretation of lacustrine flood layer records, however, requires detailed understanding of hydro-sedimentary transport and deposition processes of flood-related sediments from the catchment as a source to the lake as a sediment sink. For this purpose, a comprehensive monitoring network was set up in the catchment of Lake Mondsee. Flood and sediment transport related variables like precipitation, runoff and turbidity as a surrogate for suspended sediment concentration (SSC) are monitored at five gauges along the main tributary, the Griesler Ache River. Gauge deployment follows a nested catchment approach ranging from the headwaters to the outlet to the lake. Four monitoring buoys on the lake recording meteorological parameters as well as limno-physical variables (water temperature, turbidity, current velocity) at multiple depths of the water column are used to explore the flood-related sediment dynamics in the lake. To retrieve event-specific data on sediment deposition, two sediment trap chains were deployed, one in a proximal position to the Griesler Ache inflow and another one in a distal position in the deepest part of lake basin where sedimentation is most continuous. All units of the monitoring network collected data during the severe Central European summer flood event in June 2013. Suspended sediment concentrations could be derived from rating curves based on water samples taken automatically for

  5. Coupling alpine lake sediments with slope deposits using a combined geophysical and sedimentological approach, Leirvatnet, Jotunheimen, southern Norway

    NASA Astrophysics Data System (ADS)

    Juliussen, H.; Støren, E. N.; Lecomte, I.; Sauvin, G.; Tissot, S.; Hamran, S.-E.; Petrakov, D.; Lavrentiev, I.; Kutuzov, S.

    2012-04-01

    Lake sediments have previously been used to reconstruct debris flow activity back in time (e.g. Støren et al., 2008). In the present study we further develop this type of research by investigating direct linkages of lake sediments to specific slope deposits on land. To do this we use a combined approach, including sediment core analysis and geophysical surveys, to map colluvial deposits on a debris-flow slope and identify the associated fine-grained deposits in the adjacent Lake Leirvatnet in Jotunheimen, southern Norway. Ground Penetrating Radar (GPR) and Electrical Resistivity Tomography (ERT) are performed on the slope, and a total of 10 sediment cores and 16.6 km of GPR profiles are acquired from lake Leirvatnet. In total 20 GPR profiles was made on the lake and 10 on the adjacent slope. Frequencies used were 50 MHz on the lake and 50, 100 and 200 MHz on the slope. The lake profiles were obtained by using a 9.5 m long 110 mm plastic tube around a Rough Terrain Antenna, which was towed behind a small rubber boat. One ERT profile was made along one of the GPR profiles on land. Sediment cores were obtained from the lake using a HTH gravity corer (7 cores) and a piston corer (3 cores). Cores are analyzed using magnetic susceptibility (Bartington MS2) and an ITRAX core scanner for high-resolution X-ray fluorescence (XRF) elemental analysis and radiographic imaging. Preliminary results indicate large temporal variability in debris flows. Following the mapping and thickness estimate of the sediment cover on the lake bottom obtained from the GPR profiles, we try to evaluate the spatial continuity of reflectors associated with sections of high debris-flow activity and relate these sections to debris-flow deposits on land. The sediment thickness of meager 1 meter in the lake reflects the thin sediment cover in this high-mountain area. Three of the collected cores penetrated the sediments and went into the underlying glacial till and we therefore expect to have obtained

  6. Implications for faunal habitat related to altered macrophyte structure in regulated lakes in northern Minnesota

    USGS Publications Warehouse

    Wilcox, Douglas A.; Meeker, James E.

    1992-01-01

    Water-level regulation has altered the plant species composition and thus the structure of nearshore aquatic macrophyte communities in two regulated lakes in northern Minnesota as compared with a nearby unregulated lake. Results of previous faunal studies in the regulated lakes were used as a basis for assessing the effects of vegetation changes on faunal communities. The unregulated lake with mean annual water-level fluctuations of 1.6 m supported structurally diverse plant communities and varied faunal habitat at all depths studied. Mean annual fluctuations on one regulated lake were reduced to 1.1 m, and dense beds of four erect aquatic macrophytes dominated the 1.75-m depth that was never dewatered. We suggest that this lack of plant diversity and structural complexity resulted in diminished habitat for invertebrates, reduced availability of invertebrates as food for waterbirds and fish, reduced winter food supplies for muskrats, and reduced feeding efficiency for adult northern pike, yellow perch, and muskellunge. Mean annual fluctuations in the other regulated lake were increased to 2.7 m, and rosette and mat-forming species dominated the 1.25-m depth that was affected by winter drawdowns. We suggest that the lack of larger canopy plants resulted in poor habitat for invertebrates, reduced availability of invertebrates as food for waterbirds and fish, and poor nursery and adult feeding habitat for many species of fish. In addition, the timing and extent of winter drawdowns reduced access to macrophytes as food for muskrats and as spawning habitat for northern pike and yellow perch. In regulated lakes throughout the world, indirect effects on aquatic fauna resulting from alteration of wetland and aquatic macrophyte communities should be considered when water-level management plans are developed.

  7. Using a network of core samples to explore hydroclimatic proxy relationships within the sediments of an alpine, glacier-fed lake

    NASA Astrophysics Data System (ADS)

    Hodder, Kyle; Suchan, Jared

    2015-04-01

    Spatial and temporal variability of recent lacustrine sedimentation rates are examined for glacier-fed Mud Lake, in the Monashee Mountains of British Columbia. Clastic varve sequences in alpine, glacier-fed environments have been linked elsewhere with temperature (summer, annual), precipitation (autumn, total snowpack), and runoff (glacial, floods), and the use of varved sediments as hydroclimatic proxies is well-developed from single, but rarely multiple, core samples. In this study, a network of sediment cores (n=63) were extracted using a dense grid-sampling scheme within the 2.5 km2 distal lake basin to assess varve thickness spatially, and through time. A radioisotope profile, sediment traps and repeated coring among multiple years were used to calibrate varve-years with calendar years. Measurements of varve thickness, and sub-annual laminae thickness, were collated among cores and spanned the period 1919 - 2013 AD. The resulting five-dimensional dataset (easting, northing, depth, varve/sub-laminae thickness, time) provides a unique opportunity to explore lacustrine sedimentation. Two clear trends emerge: a general down-lake trend in thickness among most years, which is punctuated by atypical years in which thicker varves appeared in only specific portions of the lake. In the latter case, thick varves appeared either (a) along the north (right-hand) side of the lake where inflow 'hugs' the shoreline, or (b) in the deepest, distal portion of the basin. In both cases, however, atypical varves of type (a) or (b) only punctuate the general down-lake trend in thickness that develops during most years. The clear implication is that sedimentation patterns, and rates, can (but do not always) differ between years and between points in Mud Lake: there is no 'single optimum' site for a core sample. To illustrate the potential consequences on hydroclimate proxy/inference, we show how the statistical relationships between hydroclimatic records and varve thickness vary

  8. The influence of glacial meltwater on alpine aquatic ecosystems: a review.

    PubMed

    Slemmons, Krista E H; Saros, Jasmine E; Simon, Kevin

    2013-10-01

    The recent and rapid recession of alpine glaciers over the last 150 years has major implications for associated aquatic communities. Glacial meltwater shapes many of the physical features of high altitude lakes and streams, producing turbid environments with distinctive hydrology patterns relative to nival systems. Over the past decade, numerous studies have investigated the chemical and biological effects of glacial meltwater on freshwater ecosystems. Here, we review these studies across both lake and stream ecosystems. Focusing on alpine regions mainly in the Northern Hemisphere, we present examples of how glacial meltwater can affect habitat by altering physical and chemical features of aquatic ecosystems, and review the subsequent effects on the biological structure and function of lakes and streams. Collectively or separately, these factors can drive the overall distribution, diversity and behavior of primary producers, triggering cascading effects throughout the food web. We conclude by proposing areas for future research, particularly in regions where glaciers are soon projected to disappear. PMID:24056713

  9. Climate and human impacts on Lake Ammersee - Alterations in a normal range?

    NASA Astrophysics Data System (ADS)

    Vetter, M.; Büche, T.; Weinberger, S.

    2012-04-01

    Throughout the last decades of the 20th century, nutrient concentrations in some continental aquatic ecosystems increased due to human activities in their catchment areas. This is also possible to observe in the Lake Ammersee, situated in South-East of Germany, 30 km away from the City of Munich. The lake and its catchment area are representative of this type of central European water body and therefore will allow for analysis of how the lake responds to this kind of anthropogenic influence. Afterwards, in the middle of the 1980s, the problem of immense input of nutrients in the lake was detected and several management activities were carried out to keep nutrients away from this ecosystem. Hence, a trend of re-oligotrophication at the lake was observed after the middle of the 1990s. Parallel to this process, temperatures have been increasing in the northern hemisphere since the end of the 19th century. In this respect, an investigation of Lake Ammersee will be very appropriate since it may be possible to detect the difference between anthropogenic impact and possible alterations due to climate change. In this contribution, we investigated the direct anthropogenic and supra-regional climatic impacts triggered by global warming on Lake Ammersee during 1984 and 2009. Therefore we address the following questions: How do past water management activities in the Lake Ammersee catchment area affect the trophic development of the lake? What is the relationship between trophic variables chlorophyll-a concentration, water transparency or oxygen content in the lake? Is there a correlation between the signal of a changing climate and the trophic level of the lake? And, is it possible to distinguish between this (global) climate effect and direct anthropogenic pressure by land-use history? The study of dissolved oxygen, total phosphorus and chlorophyll-a, exposed a remarkable improvement in the trophic conditions of the lake. Nevertheless, a more intensive oxygen depletion in

  10. Small Changes in Climate Can Profoundly Alter the Dynamics and Ecosystem Services of Tropical Crater Lakes

    PubMed Central

    Saulnier-Talbot, Émilie; Gregory-Eaves, Irene; Simpson, Kyle G.; Efitre, Jackson; Nowlan, Tobias E.; Taranu, Zofia E.; Chapman, Lauren J.

    2014-01-01

    African tropical lakes provide vital ecosystem services including food and water to some of the fastest growing human populations, yet they are among the most understudied ecosystems in the world. The consequences of climate change and other stressors on the tropical lakes of Africa have been informed by long-term analyses, but these studies have largely focused on the massive Great Rift Valley lakes. Our objective was to evaluate how recent climate change has altered the functioning and services of smaller tropical lakes, which are far more abundant on the landscape. Based on a paired analysis of 20 years of high-resolution water column data and a paleolimnological record from a small crater lake in western Uganda, we present evidence that even a modest warming of the air (∼0.9°C increase over 20 years) and changes in the timing and intensity of rainfall can have significant consequences on the dynamics of this common tropical lake type. For example, we observed a significant nonlinear increase (R2adj = 0.23, e.d.f. = 7, p<0.0001) in thermal stability over the past 20 years. This resulted in the expansion of anoxic waters and consequent deterioration of fish habitat and appears to have abated primary production; processes that may impair ecosystem services for a vulnerable human population. This study on a system representative of small tropical crater lakes highlights the far-reaching effects of global climatic change on tropical waters. Increased research efforts into tropical aquatic ecosystem health and the development of sound management practices are necessary in order to strengthen adaptive capabilities in tropical regions. PMID:24497954

  11. Small changes in climate can profoundly alter the dynamics and ecosystem services of tropical crater lakes.

    PubMed

    Saulnier-Talbot, Émilie; Gregory-Eaves, Irene; Simpson, Kyle G; Efitre, Jackson; Nowlan, Tobias E; Taranu, Zofia E; Chapman, Lauren J

    2014-01-01

    African tropical lakes provide vital ecosystem services including food and water to some of the fastest growing human populations, yet they are among the most understudied ecosystems in the world. The consequences of climate change and other stressors on the tropical lakes of Africa have been informed by long-term analyses, but these studies have largely focused on the massive Great Rift Valley lakes. Our objective was to evaluate how recent climate change has altered the functioning and services of smaller tropical lakes, which are far more abundant on the landscape. Based on a paired analysis of 20 years of high-resolution water column data and a paleolimnological record from a small crater lake in western Uganda, we present evidence that even a modest warming of the air (∼0.9°C increase over 20 years) and changes in the timing and intensity of rainfall can have significant consequences on the dynamics of this common tropical lake type. For example, we observed a significant nonlinear increase (R(2) adj  = 0.23, e.d.f. = 7, p<0.0001) in thermal stability over the past 20 years. This resulted in the expansion of anoxic waters and consequent deterioration of fish habitat and appears to have abated primary production; processes that may impair ecosystem services for a vulnerable human population. This study on a system representative of small tropical crater lakes highlights the far-reaching effects of global climatic change on tropical waters. Increased research efforts into tropical aquatic ecosystem health and the development of sound management practices are necessary in order to strengthen adaptive capabilities in tropical regions. PMID:24497954

  12. Characterization of rhizosphere and endophytic fungal communities from roots of Stipa purpurea in alpine steppe around Qinghai Lake.

    PubMed

    Lu, Dengxue; Jin, Hui; Yang, Xiaoyan; Zhang, Denghong; Yan, Zhiqiang; Li, Xiuzhuang; Zhao, Yuhui; Han, Rongbing; Qin, Bo

    2016-08-01

    Stipa purpurea is among constructive endemic species in the alpine steppe on the Qinghai-Xizang Plateau. To reveal the fungal community structure and diversity in the rhizosphere and roots of this important grass and to analyze the potential influence of different habitats on the structure of fungal communities, we explored the root endophyte and the directly associated rhizosphere communities of S. purpurea by using internal transcribed spacer rRNA cloning and sequencing methods. We found that the roots of S. purpurea are associated with a diverse consortium of Basidiomycota (59.8%) and Ascomycota (38.5%). Most fungi obtained from rhizosphere soil in S. purpurea have been identified as Ascomycetes, while the high proportion detected in roots were basidiomycetous endophytes. The species richness, diversity, and evenness of fungal assemblages were higher in roots than in the rhizosphere soil. Fungi inhabiting the rhizosphere and roots of S. purpurea are significantly different, and the rhizosphere and endophyte communities are largely independent with little overlap in the dominant phyla or operational taxonomic units. Taken together, these results suggested that a wide variety of fungal communities are associated with the roots and rhizosphere soil of S. purpurea and that the fungal assemblages are strongly influenced by different habitats. PMID:27348421

  13. Climate change and human activities altered the diversity and composition of soil microbial community in alpine grasslands of the Qinghai-Tibetan Plateau.

    PubMed

    Zhang, Yong; Dong, Shikui; Gao, Qingzhu; Liu, Shiliang; Zhou, Huakun; Ganjurjav, Hasbagan; Wang, Xuexia

    2016-08-15

    Alpine ecosystems are known to be sensitive to climate change and human disturbances. However, the knowledge about the changes of their underground microbial communities is inadequate. We explored the diversity and structure of soil bacterial and fungal communities using Ilumina MiSeq sequencing in native alpine grasslands (i.e. the alpine meadow, alpine steppe) and cultivated grassland of the Qinghai-Tibetan Plateau (QTP) under three-year treatments of overgrazing, warming and enhanced rainfall. Enhanced rainfall rather than warming significantly reduced soil microbial diversity in native alpine grasslands. Variable warming significantly reduced it in the cultivated grassland. Over 20% and 40% variations of microbial diversity could be explained by soil nutrients and moisture in the alpine meadow and cultivated grassland, separately. Soil microbial communities could be clustered into different groups according to different treatments in the alpine meadow and cultivated grassland. For the alpine steppe, with the lowest soil nutrients and moistures, <10% variations of microbial diversity was explained by soil properties; and the soil microbial communities among different treatments were similar. The soil microbial community in the cultivated grassland was varied from it in native grasslands. Over 50% variations of soil microbial communities among different treatments were explained by soil nutrients and moisture in each grassland type. Our results suggest that climate change and human activities strongly affected soil microbial communities by changing soil nutrients and moistures in alpine grassland ecosystems. PMID:27100015

  14. Homogenised daily lake surface water temperature data generated from multiple satellite sensors: A long-term case study of a large sub-Alpine lake

    PubMed Central

    Pareeth, Sajid; Salmaso, Nico; Adrian, Rita; Neteler, Markus

    2016-01-01

    Availability of remotely sensed multi-spectral images since the 1980’s, which cover three decades of voluminous data could help researchers to study the changing dynamics of bio-physical characteristics of land and water. In this study, we introduce a new methodology to develop homogenised Lake Surface Water Temperature (LSWT) from multiple polar orbiting satellites. Precisely, we developed homogenised 1 km daily LSWT maps covering the last 30 years (1986 to 2015) combining data from 13 satellites. We used a split-window technique to derive LSWT from brightness temperatures and a modified diurnal temperature cycle model to homogenise data which were acquired between 8:00 to 17:00 UTC. Gaps in the temporal LSWT data due to the presence of clouds were filled by applying Harmonic ANalysis of Time Series (HANTS). The satellite derived LSWT maps were validated based on long-term monthly in-situ bulk temperature measurements in Lake Garda, the largest lake in Italy. We found the satellite derived homogenised LSWT being significantly correlated to in-situ data. The new LSWT time series showed a significant annual rate of increase of 0.020 °C yr−1 (*P < 0.05), and of 0.036 °C yr−1 (***P < 0.001) during summer. PMID:27502177

  15. Homogenised daily lake surface water temperature data generated from multiple satellite sensors: A long-term case study of a large sub-Alpine lake.

    PubMed

    Pareeth, Sajid; Salmaso, Nico; Adrian, Rita; Neteler, Markus

    2016-01-01

    Availability of remotely sensed multi-spectral images since the 1980's, which cover three decades of voluminous data could help researchers to study the changing dynamics of bio-physical characteristics of land and water. In this study, we introduce a new methodology to develop homogenised Lake Surface Water Temperature (LSWT) from multiple polar orbiting satellites. Precisely, we developed homogenised 1 km daily LSWT maps covering the last 30 years (1986 to 2015) combining data from 13 satellites. We used a split-window technique to derive LSWT from brightness temperatures and a modified diurnal temperature cycle model to homogenise data which were acquired between 8:00 to 17:00 UTC. Gaps in the temporal LSWT data due to the presence of clouds were filled by applying Harmonic ANalysis of Time Series (HANTS). The satellite derived LSWT maps were validated based on long-term monthly in-situ bulk temperature measurements in Lake Garda, the largest lake in Italy. We found the satellite derived homogenised LSWT being significantly correlated to in-situ data. The new LSWT time series showed a significant annual rate of increase of 0.020 °C yr(-1) (*P < 0.05), and of 0.036 °C yr(-1) (***P < 0.001) during summer. PMID:27502177

  16. Homogenised daily lake surface water temperature data generated from multiple satellite sensors: A long-term case study of a large sub-Alpine lake

    NASA Astrophysics Data System (ADS)

    Pareeth, Sajid; Salmaso, Nico; Adrian, Rita; Neteler, Markus

    2016-08-01

    Availability of remotely sensed multi-spectral images since the 1980’s, which cover three decades of voluminous data could help researchers to study the changing dynamics of bio-physical characteristics of land and water. In this study, we introduce a new methodology to develop homogenised Lake Surface Water Temperature (LSWT) from multiple polar orbiting satellites. Precisely, we developed homogenised 1 km daily LSWT maps covering the last 30 years (1986 to 2015) combining data from 13 satellites. We used a split-window technique to derive LSWT from brightness temperatures and a modified diurnal temperature cycle model to homogenise data which were acquired between 8:00 to 17:00 UTC. Gaps in the temporal LSWT data due to the presence of clouds were filled by applying Harmonic ANalysis of Time Series (HANTS). The satellite derived LSWT maps were validated based on long-term monthly in-situ bulk temperature measurements in Lake Garda, the largest lake in Italy. We found the satellite derived homogenised LSWT being significantly correlated to in-situ data. The new LSWT time series showed a significant annual rate of increase of 0.020 °C yr‑1 (*P < 0.05), and of 0.036 °C yr‑1 (***P < 0.001) during summer.

  17. Paleoflood activity and climate change over the last 2000 years recorded by high altitude alpine lake sediments in Western French Alps.

    NASA Astrophysics Data System (ADS)

    Fouinat, Laurent; Sabatier, Pierre; Develle, Anne-Lise; Giguet-Covex, Charline; Poulenard, Jérôme; Doyen, Elise; Crouzet, Christian; Malet, Emmanuel; Reyss, Jean-Louis; Arnaud, Fabien

    2015-04-01

    Extreme precipitation events can trigger floods that may have serious human and economic consequences. The flood represents extreme rainfall event, which in high altitude mountain regions are mostly triggered alternatively by local convective summer storms or, less frequently, by regional widespread rainfall event. The former's precipitation pattern comes from Mediterranean Sea fluxes, dominant in the south; instead of the latter coming from the Atlantic Ocean, dominant in the north of the French Alps. The aim of the study is then to explore which regime dominates in Western French Alps. Paleoflood chronicle is a way to understand past continental climate through the variability of both frequency and intensity. In this study we explore the paleoflood activity as recorded by sediments of the small alpine lake Muzelle (2200 m.a.s.l.) located in the western French Alps. Lake Muzelle catchment area is 5 km² -around 4 % being glacier covered- and is drained by one main stream. Lake Muzelle is 18.8 meters deep and is ice-covered during 7-8 months each year. Moreover, the watershed is being used for pastoral activity for several centuries. In this study, we use sedimentological analysis as well high resolution XRF core scanner geochemistry to identify turbidites interpreted as flood deposits. 256 turbidites were documented in the sediment sequence. Sr/Ti geochemical ratio is used to identify the coarsest grain size fraction of the flood deposit and the thickness of each deposit was measured. Dating was carried out using short-lived-radio-elements (210Pb, 137Cs, 241Am), historical events as well as nine 14C dates and paleomagnetic declination to constrain the age model over the last 2000 years. The study includes also palynological and sediment DNA analysis to understand past human activity on the watershed. As a result, the 31 years frequency shows a stable period from 0 to 1100 AD. Between 1100 and1200 AD the flood frequency presents a brutal increase with a relatively

  18. Fingerprinting of glacial silt in lake sediments yields continuous records of alpine glaciation (35–15 ka), western USA

    USGS Publications Warehouse

    Rosenbaum, Joseph G.; Reynolds, Richard L.; Colman, Steven M.

    2012-01-01

    Fingerprinting glacial silt in last glacial-age sediments from Upper Klamath Lake (UKL) and Bear Lake (BL) provides continuous radiocarbon-dated records of glaciation for the southeastern Cascade Range and northwestern Uinta Mountains, respectively. Comparing of these records to cosmogenic exposure ages from moraines suggests that variations in glacial flour largely reflect glacial extent. The two areas are at similar latitudes and yield similar records of glacial growth and recession, even though UKL lies less than 200 km from the ocean and BL is in the continental interior. As sea level began to fall prior to the global Last Glacial Maximum (LGM), existing glaciers in the UKL area expanded. Near the beginning of the global LGM (26.5 ka), the BL record indicates onset of glaciation and UKL-area glaciers underwent further expansion. Both records indicate that local glaciers reached their maximum extents near the end of the global LGM, remained near their maxima for ~1000 yr, and underwent two stages of retreat separated by a short period of expansion.

  19. Structural and alteration controls on gold mineralization the of the amphibolite facies Detour Lake Deposit, Canada

    NASA Astrophysics Data System (ADS)

    Dubosq, Renelle; Schneider, David

    2016-04-01

    The 15M oz Detour Lake deposit is a Neoarchean orogenic gold ore body located in the northern most region of the Abitibi district within the Superior Province. The mine is an open pit design in the high strain zone of the Sunday Lake Deformation Zone (SLDZ). The ductile-brittle SLDZ parallels the broadly E-W Abitibi greenstone belt and the deposit is situated in a dilation zone between volcanoclastic rocks of the Caopatina Assemblage and Lower Detour Lake Formation, consisting of ultramafic talc-chlorite-sericite schist. The Upper Detour Lake Formation consists of pillowed and massive flows and hyloclastic units crosscut by minor felsic to intermediate dykes. All of the formations are sub-vertical, north-dipping units with stretching lineations indicating dip-slip motion. The Detour deposit differs from other classic ore deposits in the dominantly greenschist facies Abitibi Subprovince by possessing an amphibolite facies metamorphic assemblage of actinolite-biotite-plagioclase-almandine. Consequently, the typical indicator minerals used to identify alteration and mineralization, such as secondary biotite, may not be useful. Petrological and geochemical analyses have revealed at least four populations of biotite: 1) large euhedral crystals located within quartz-carbonate veins, 2) small, euhedral zoned crystals present as alteration haloes, 3) very small, anhedral to subhedral indistinct crystal present in mafic volcanic host rock, and 4) large euhedral crystals defining the main metamorphic foliation in the metasediments. Extensive examination of mineral assemblages, alteration products, and vein structure in rock core across barren and mineralized zones has documented over a dozen vein types which can be grouped into two main categories: 1) sulfidized quartz-carbonate veins associated with biotite alteration and 2) late carbonate veins. Gold grades do not prove to be dependent on vein type but rather on the host rock composition: the highest ore grades are present

  20. Lake surface water temperatures of European Alpine lakes (1989-2013) based on the Advanced Very High Resolution Radiometer (AVHRR) 1 km data set

    NASA Astrophysics Data System (ADS)

    Riffler, M.; Lieberherr, G.; Wunderle, S.

    2015-02-01

    Lake water temperature (LWT) is an important driver of lake ecosystems and it has been identified as an indicator of climate change. Consequently, the Global Climate Observing System (GCOS) lists LWT as an essential climate variable. Although for some European lakes long in situ time series of LWT do exist, many lakes are not observed or only on a non-regular basis making these observations insufficient for climate monitoring. Satellite data can provide the information needed. However, only few satellite sensors offer the possibility to analyse time series which cover 25 years or more. The Advanced Very High Resolution Radiometer (AVHRR) is among these and has been flown as a heritage instrument for almost 35 years. It will be carried on for at least ten more years, offering a unique opportunity for satellite-based climate studies. Herein we present a satellite-based lake surface water temperature (LSWT) data set for European water bodies in or near the Alps based on the extensive AVHRR 1 km data record (1989-2013) of the Remote Sensing Research Group at the University of Bern. It has been compiled out of AVHRR/2 (NOAA-07, -09, -11, -14) and AVHRR/3 (NOAA-16, -17, -18, -19 and MetOp-A) data. The high accuracy needed for climate related studies requires careful pre-processing and consideration of the atmospheric state. The LSWT retrieval is based on a simulation-based scheme making use of the Radiative Transfer for TOVS (RTTOV) Version 10 together with ERA-interim reanalysis data from the European Centre for Medium-range Weather Forecasts. The resulting LSWTs were extensively compared with in situ measurements from lakes with various sizes between 14 and 580 km2 and the resulting biases and RMSEs were found to be within the range of -0.5 to 0.6 K and 1.0 to 1.6 K, respectively. The upper limits of the reported errors could be rather attributed to uncertainties in the data comparison between in situ and satellite observations than inaccuracies of the satellite

  1. Decreased glutathione S-transferase expression and activity and altered sex steroids in Lake Apopka brown bullheads (Ameriurus nebulosus)

    USGS Publications Warehouse

    Gallagher, E.P.; Gross, T.S.; Sheehy, K.M.

    2001-01-01

    A number of freshwater lakes and reclaimed agricultural sites in Central Florida have been the receiving waters for agrochemical and municipal runoff. One of these sites, Lake Apopka, is also a eutrophic system that has been the focus of several case studies reporting altered reproductive activity linked to bioaccumulation of persistent organochlorine chemicals in aquatic species. The present study was initiated to determine if brown bullheads (Ameriurus nebulosus) from the north marsh of Lake Apopka (Lake Apopka Marsh) exhibit an altered capacity to detoxify environmental chemicals through hepatic glutathione S-transferase (GST)-mediated conjugation as compared with bullheads from a nearby reference site (Lake Woodruff). We also compared plasma sex hormone concentrations (testosterone, 17-?? estradiol, and 11 keto-testosterone) in bullheads from the two sites. Female bullheads from Lake Apopka had 40% lower initial rate GST conjugative activity toward 1-chloro-2,4-dinitrobenzene (CDNB), 50% lower activity towards p-nitrobutyl chloride (NBC), 33% lower activity toward ethacrynic acid (ECA), and 43% lower activity toward ??5-androstene-3,17-dione (??5-ADI), as compared with female bullheads from Lake Woodruff. Enzyme kinetic analyses demonstrated that female bullheads from Lake Apopka had lower GST-catalyzed CDNB clearance than did female Lake Woodruff bullheads. Western blotting studies of bullhead liver cytosolic proteins demonstrated that the reduced GST catalytic activities in female Lake Apopka bullheads were accompanied by lower expression of hepatic GST protein. No site differences were observed with respect to GST activities or GST protein expression in male bullheads. Female Lake Apopka bullheads also had elevated concentrations of plasma androgens (testosterone and 11-ketotestosterone) as compared with females from Lake Woodruff. In contrast, male Lake Apopka bullheads had elevated levels of plasma estrogen but similar levels of androgens as compared with

  2. Tracking Holocene glacial and high-altitude alpine environments fluctuations from minerogenic and organic markers in proglacial lake sediments (Lake Blanc Huez, Western French Alps)

    NASA Astrophysics Data System (ADS)

    Simonneau, Anaëlle; Chapron, Emmanuel; Garçon, Marion; Winiarski, Thierry; Graz, Yann; Chauvel, Catherine; Debret, Maxime; Motelica-Heino, Mickaël; Desmet, Marc; Di Giovanni, Christian

    2014-04-01

    Holocene palaeoenvironmental evolution and glacial fluctuations at high-altitude in the western French Alps are reconstructed based on a multiproxy approach within Lake Blanc Huez (2550 m a.s.l.) drainage basin. The combination of seismic profiling (3.5 kHz), piston coring and radiocarbon dating in proglacial lacustrine sediments together with a detailed organic analysis of autochthonous and allochthonous supply allows documenting the evolution of glacier activity during the Holocene. Over the last 9700 years, the Holocene lake record has a bimodal pattern whose transition is progressive and occurring between 5400 and 4700 cal BP. During the Early Holocene, the organic lacustrine facies reflects reduced glacial activity in the catchment. This major glacial retreat seems to result from solar forcing and high summer insolation. After 5400 cal BP, lacustrine sedimentation is marked by the gradual increase both of minerogenic supply and soil erosion, suggesting a progressive transition to wetter climatic conditions. This climate change is synchronous both from the gradual decrease of summer insolation and the gradual reorganization of oceanic and atmospheric circulations, characterizing the beginning of the Neoglacial period. Both colder temperature and humid climate induced significant glacier advance, since 4700 cal BP. Over this global trend, three periods are particularly associated with higher runoff processes and higher soil erosion interpreted as wetter time intervals resulting from enhanced northern Westerlies regimes across the North Atlantic and Western Europe. They are dated from 8700 to 7000, 4700 to 2500 and 1200 to 200 cal BP. These wetter phases drastically contrast with periods of reduced glacial activities dated from the Early Bronze Age (ca 3870-3770 cal BP), the Iron Age (ca 2220-2150 cal BP), the Roman period (ca AD115-330) and the Medieval Warm Period (ca AD760-1160). In addition, these dryer periods are associated with mining activities at high-altitude.

  3. Two millennia of torrential activity reconstructed from alpine lake sediments: towards regional patterns of extreme precipitation changes

    NASA Astrophysics Data System (ADS)

    Wilhelm, B.; Arnaud, F.; Giguet-Covex, C.; Sabatier, P.; Crouzet, C.; Delannoy, J. J.

    2012-04-01

    In mountain areas extreme precipitation events trigger torrential floods, characterized by a sudden and intense rise of discharge causing large human and economic losses. Their frequency and/or intensity are expected to increase in the context of global warming. However, the relationship between such events and climate changes remains difficult to assess. Long-term geological records of intense events could enable to extend documented records beyond the observational data for a better understanding of local to regional flood hazard patterns in relation to past climatic changes and hence improving predictive models. In this context, lake sediment records appear a relevant archive as they are continuous records in which the identification of high-energy sediment layers allows to reconstruct flood calendar. In addition, the flood intensity can be reconstructed from the coarse fraction of each flood layer. Frequency and intensity of past torrential floods were thus reconstructed from four high-elevation lake records of the French Alps, in the framework of Pygmalion research program. Studied sites were selected along a north-south transect over this region to investigate the flooding responses to different climatic influences (westerlies in the north and Mediterranean influences in the south). High-resolution geochemical and sedimentological analyses were undertaken for an exhaustive identification of flood layers and several dating methods (short-lived radionuclides, 14C, correlation with historic events, paleomagnetism) were combined to reduce age uncertainties as much as possible. Over the entire French Alps, the torrential-flood frequency increases at a secular timescale during the cold period of the Little Ice Age (LIA; 1300-1900 AD). This increase seems in agreement with a regional high wetness, already described in the literature, possibly related to an increase in cyclonic activity. Superimposed to this secular trend, a pluri-decadal variability appears at

  4. Late Pleistocene and Holocene Hydroclimate Variability in the Tropical Andes from Alpine Lake Sediments, Cordillera de Mérida, Venezuela

    NASA Astrophysics Data System (ADS)

    Larsen, D. J.; Abbott, M. B.; Polissar, P. J.

    2014-12-01

    The tropics play a major role in the global hydrologic cycle and changes to tropical rainfall patterns have critical implications for water resources and ecosystem dynamics over large geographic scales. In tropical South America, late Pleistocene and Holocene precipitation variability has been documented in geologic records and associated with numerous external and internal variables, including changes in summer insolation, South American summer monsoon strength, Pacific Ocean sea surface temperatures, continental moisture recycling, and other climate processes. However, there are few records from the northern hemisphere tropical Americas, a key region for understanding interhemispheric linkages and the drivers of tropical hydroclimate variability. Here, we present a ~13 ka record of coupled hydroclimate and environmental changes from Laguna Brava, a small (~0.07 km2), hydrologically closed lake basin situated at 2400 m asl in the Cordillera de Mérida, Venezuela. Sediment cores collected from varying water depths and proximity to shore are placed in a chronologic framework using radiocarbon ages from terrestrial macrofossils, and analyzed for a suite of physical, bulk geochemical, and stable isotopic parameters. Compound specific hydrogen isotope (D/H) measurements of terrestrial plant waxes (long-chain n-alkanes) show a sharp increase in the late Pleistocene, followed by a long-term trend toward more negative values that suggest a ~20‰ decrease in the D/H ratios of South American tropical precipitation during the Holocene. This pattern is consistent in sign and magnitude to other South American precipitation reconstructions from both hemispheres, indicating interhemispheric similarities in tropical hydroclimate variability. Superimposed on this continent-scale trend are changes in moisture balance and environmental conditions in the Venezuelan Andes. We reconstruct these parameters at Laguna Brava at multidecadal and centennial resolution and evaluate this

  5. Potential for large-bodied zooplankton and dreissenids to alter the productivity and autotrophic structure of lakes.

    PubMed

    Higgins, Scott N; Althouse, B; Devlin, S P; Vadeboncoeur, Y; Vander Zanden, M J

    2014-08-01

    While limnological studies have emphasized the importance of grazers on algal biomass and primary production in pelagic habitats, few studies have examined their potential role in altering total ecosystem primary production and it's partitioning between pelagic and benthic habitats. We modified an existing ecosystem production model to include biotic feedbacks associated with two groups of large-bodied grazers of phytoplankton (large-bodied zooplankton and dreissenid mussels) and estimated their effects on total ecosystem production (TEP), and the partitioning of TEP between phytoplankton and periphyton (autotrophic structure) across large gradients in lake size and total phosphorus (TP) concentration. Model results indicated that these filter feeders were capable of reducing whole-lake phytoplankton production by 20-70%, and increasing whole-lake benthic production between 0% and 600%. Grazer effects on TEP were constrained by lake size, trophic status, and potential feedbacks between grazing and maximum rates of benthic photosynthesis (BP(MAX)). In small (mean depth Z < 10 m) oligotrophic and mesotrophic (TP < 100 mg P/m2) lakes, both large-bodied zooplankton and dreissenids were capable of increasing the benthic fraction (Bf) by 10-50% of TEP. Small lakes were also the only systems where TEP had the potential to increase in the presence of large-bodied grazers, but such increases only occurred if grazer-induced changes in water clarity, macrophyte coverage, or nutrient availability stimulated specific growth rates of periphyton. In other scenarios, TEP declined by a maximum of 50%. In very large lakes (Z > 100 m), Bf was minor (< 10%) in the presence or absence of grazers, but increases in littoral habitat and the stimulation of benthic production in these ecosystems could be of ecological relevance because littoral zones in large lakes contain a relatively high proportion of within-lake biodiversity and are important for whole-lake food webs. PMID:25230476

  6. Lake

    ERIC Educational Resources Information Center

    Wien, Carol Anne

    2008-01-01

    The lake is blue black and deep. It is a glaciated finger lake, clawed out of rock when ice retracted across Nova Scotia in a northerly direction during the last ice age. The lake is narrow, a little over a mile long, and deep, 90 to 190 feet in places according to local lore, off the charts in others. The author loves to swim there, with a sense…

  7. Flood-Induced Surface Blooms Alter Deep Chlorophyll Maxima Community Structure in Lake Michigan.

    NASA Astrophysics Data System (ADS)

    Aguilar, C.; Cuhel, R. L.; Seline, L.

    2008-12-01

    Watershed-wide floods can bring increased nutrients and phytoplankton to receiving waters. This input can alter physical, chemical and phytoplankton community structure in a major way. Phytoplankton species composition and size distribution are key factors in their use as ecological indicators. Since 2003, phytoplankton communities in Lake Michigan have shifted from diatom and big cell (>10μm)- dominated to small cell picocyanobacteria-dominated phytoplankton (<3μm). Picoplankton typically thrive under lower light conditions than diatoms, are adapted with phycobiliprotein pigments for deepwater light quality, have a higher surface-to-volume ratio for effective nutrient scavenging, and are smaller than the preferred range (5-100μm) for filter-feeding mussel populations. After only five years with Quagga Mussels, dampened seasonal cycling of silicate indicated a basin-wide reduction of diatom production, and unicellular Cyanobacteria became dominant in deep chlorophyll maximum (DCM) zones. In the DCM, Synechococcus-like cells reached populations of at least 210,000 cells/ml. DCM chlorophyll (chl) remained similar (3-4μg/l) but late summer species composition changed dramatically to mostly <3μm cells. During the June 2008 Midwest floods, the rivers into Lake Michigan discharged at over 30 times the rate of water typically flowing into the lake. Nearshore phytoplankton were dominated by diatoms localized in the epilimnion (upper 5-10m). Chl increased several-fold in surface waters and diatom biomass increased from the previous years. The 1% PAR penetration changed from 35-40m previously to only 25m in 2008. Chl in the >10μm fraction increased from previous years, and over 75% of the particulate Si was also in this size fraction. Because of the rapid sinking of diatoms during calm weather of late June-early July of 2008, particulate Si did not reach high values in surfaces waters (ca. 1.5μM) but remained at a consistently higher level than in 2007. Sinking of

  8. Crystallization process of zircon and fergusonite during hydrothermal alteration in Nechalacho REE deposit, Thor Lake, Canada

    NASA Astrophysics Data System (ADS)

    Hoshino, M.; Watanabe, Y.; Murakami, H.; Kon, Y.; Tsunematsu, M.

    2012-04-01

    The core samples of two drill holes, which penetrate sub-horizontal mineralized horizons at Nechalacho REE deposit in the Proterozoic Thor Lake syenite, Canada, were studied in order to clarify magmatic and hydrothermal processes that enriched HFSE (e.g. Zr, Nb, Y and REE). Zircon is the most common REE minerals in Nechalacho REE deposit. The zircon is divided into five types as follows: Type-1 zircon occurs as single grain in phlogopite and the chondrite-normalized REE pattern is characterized by a steeply-rising slope from the LREE to the HREE with a positive Ce-anomaly and negative Eu-anomaly. This chemical characteristic is similar to that of igneous zircon. Type-2 zircon consists of HREE-rich magmatic porous core and LREE-Nb-F-rich hydrothermal rim. This type zircon is mostly included in phlogopite and fluorite, and occasionally in microcline. Type-3 zircon is characterized by euhedral to anhedral crystal, occurring in a complex intergrowth with REE fluorocarbonates. Type-3 zircons have high contents of REE, Nb and fluorine. Type-4 zircon consists of porous-core and -rim zones, but their chemical compositions are similar to each other. This type zircon is a subhedral crystal rimmed by fergusonite. Type-5 zircon is characterized by smaller, porous and subhedral to anhedral crystals. The interstices between small zircons are filled by fergusonite. Type-4 and -5 zircons show low REE and Nb contents. Occurrences of these five types of zircon are different according to the depth and degree of the alteration by hydrothermal solutions rich in F- and CO3 of the two drill holes, which permit a model for evolution of the zircon crystallization in Nechalacho REE deposit as follows: (1) type-1 (single magmatic zircon) is formed in miaskitic syenite. (2) LREE-Nb-F-rich hydrothermal zircon formed around HREE-rich magmatic zircon (type-2 zircon); (3) type-3 zircon crystallized thorough F and CO3-rich hydrothermal alteration of type-2 zircon which formed the complex

  9. Alpine Microbial Community Responses to Climate Change and Atmospheric Nitrogen Deposition in Rocky Mountain National Park

    NASA Astrophysics Data System (ADS)

    Osborne, B. B.; Baron, J.; Wallenstein, M. D.; Richer, E.

    2010-12-01

    Remote alpine ecosystems of the western US exhibit vulnerability to anthropogenic drivers of change. Atmospheric nitrogen (N) deposition and a changing climate introduce nutrients, alter hydrological processes, and expose soils to modified temperature regimes. We cannot yet predict the interacting effects and far-reaching biogeochemical consequences of this influence. Importantly, long-term data reveal headwater nitrate (NO3-) concentration trends increasing >50% from the 1990s to 2006 along the Colorado Front Range in conjunction with warm summer temperatures. Such a change in nutrient cycling raises concern for eutrophication in nutrient-poor alpine lakes. Increasing stream NO3- suggests terrestrial microbes may be responding to changes in important controls of community development and activity: temperature and ammonium (NH4+) availability. Nitrifying bacteria and archaea strongly influence alpine soil NO3- concentrations. Little is understood about alpine microbes. Our research characterizes nitrifier abundance and activity in alpine substrates by exposing them to experimental NH4+ and temperature treatments. Soil substrates fall along a gradient of succession commonly represented in alpine catchments due to deglaciation. These include well-developed meadow soils, unvegetated talus substrate, and newly-exposed glacial sediments. All three substrate types were collected from the Loch Vale watershed in Rocky Mountain National Park, a long-term research site in the Colorado Front Range known to receive elevated levels of atmospheric N deposition. All soils have been evaluated for initial %C, %N, microbial biomass, NO3-, NH4+, and DOC concentrations, and nitrifier abundance. After temperature and NH4+ treatments, samples will be evaluated for changes in biomass and nitrifier abundance as well as net and gross nitrification. Linking the influence of relative soil temperature and NH4+ concentrations on alpine substrates, at a range of successional stages, will

  10. Well construction information, lithologic logs, water level data, and overview of research in Handcart Gulch, Colorado: an alpine watershed affected by metalliferous hydrothermal alteration

    USGS Publications Warehouse

    Caine, Jonathan Saul; Manning, Andrew H.; Verplanck, Philip L.; Bove, Dana J.; Kahn, Katherine Gurley; Ge, Shemin

    2006-01-01

    Integrated, multidisciplinary studies of the Handcart Gulch alpine watershed provide a unique opportunity to study and characterize the geology and hydrology of an alpine watershed along the Continental Divide. The study area arose out of the donation of four abandoned, deep mineral exploration boreholes to the U.S. Geological Survey for research purposes by Mineral Systems Inc. These holes were supplemented with nine additional shallow holes drilled by the U.S. Geological Survey along the Handcart Gulch trunk stream. All of the holes were converted into observation wells, and a variety of data and samples were measured and collected from each. This open-file report contains: (1) An overview of the research conducted to date in Handcart Gulch; (2) well location, construction, lithologic log, and water level data from the research boreholes; and (3) a brief synopsis of preliminary results. The primary purpose of this report is to provide a research overview as well as raw data from the boreholes. Interpretation of the data will be reported in future publications. The drill hole data were tabulated into a spreadsheet included with this digital open-file report.

  11. Alterations in histology and antioxidant defense system in the testes of the lake Van fish (Alburnus tarichi Güldenstädt, 1814).

    PubMed

    Kaptaner, Burak; Kankaya, Ertuğrul; Dogan, Abdulahad; Durmuş, Atilla

    2016-08-01

    Recent reports have demonstrated gonadal abnormalities in the Lake Van fish (Alburnus tarichi) from Lake Van caused by increasing pollution. In the present study, the fish was collected from an area of Lake Van receiving mainly sewage treatment plant effluent at prespawning period (April) and from a river (Karasu) which is close to the polluted area of the lake and where the fish migrates at spawning period (May). Collected specimens were examined for testicular alterations, gonadosomatic index (GSI), condition factor (CF), and antioxidant defense system biomarkers based on comparison with a reference lake (Erçek) and a reference freshwater inlet (Memedik River). Histological examinations of the testes of fish from the polluted area and the connected river showed various alterations consisting of macrophage aggregates, vacuolation, pyknosis, germ cell degeneration, seminiferous tubule dilation, disorganization of tubules, reduced spermatozoa, and fibrosis. A lower GSI and CF were also observed. Moreover, alterations in the antioxidant system biomarkers were determined in the testis tissues of fish from the Lake Van and Karasu River, indicating oxidative stress. These results suggest that the abnormalities in the testes are causally related to the increased oxidative stress, and pollution in Lake Van may have adversely affected the reproductive health of the lake Van fish. PMID:27435621

  12. Sensitivity of alpine and subalpine lakes to acidification from atmospheric deposition in Grand Teton National Park and Yellowstone National Park, Wyoming

    USGS Publications Warehouse

    Nanus, Leora; Campbell, Donald H.; Williams, Mark W.

    2005-01-01

    The sensitivity of 400 lakes in Grand Teton and Yellowstone National Parks to acidification from atmospheric deposition of nitrogen and sulfur was estimated based on statistical relations between acid-neutralizing capacity concentrations and basin characteristics to aid in the design of a long-term monitoring plan for Outstanding Natural Resource Waters. Acid-neutralizing capacity concentrations that were measured at 52 lakes in Grand Teton and 23 lakes in Yellowstone during synoptic surveys were used to calibrate the statistical models. Three acid-neutralizing capacity concentration bins (bins) were selected that are within the U.S. Environmental Protection Agency criteria of sensitive to acidification; less than 50 microequivalents per liter (?eq/L) (0-50), less than 100 ?eq/L (0-100), and less than 200 ?eq/L (0-200). The development of discrete bins enables resource managers to have the ability to change criteria based on the focus of their study. Basin-characteristic information was derived from Geographic Information System data sets. The explanatory variables that were considered included bedrock type, basin slope, basin aspect, basin elevation, lake area, basin area, inorganic nitrogen deposition, sulfate deposition, hydrogen ion deposition, basin precipitation, soil type, and vegetation type. A logistic regression model was developed and applied to lake basins greater than 1 hectare in Grand Teton (n = 106) and Yellowstone (n = 294). A higher percentage of lakes in Grand Teton than in Yellowstone were predicted to be sensitive to atmospheric deposition in all three bins. For Grand Teton, 7 percent of lakes had a greater than 60-percent probability of having acid-neutralizing capacity concentrations in the 0-50 bin, 36 percent of lakes had a greater than 60-percent probability of having acid-neutralizing capacity concentrations in the 0-100 bin, and 59 percent of lakes had a greater than 60-percent probability of having acid-neutralizing capacity

  13. ALTERATIONS IN SEXUALLY DIMORPHIC BIOTRANSFORMATION OF TESTOSTERONE IN JUVENILE AMERICAN ALLIGATORS (ALLIGATOR MISSISSIPPIENSIS) FROM CONTAMINATED LAKES

    EPA Science Inventory

    The goal of this study was to determine whether hepatic biotransformation of testosterone is normally sexually dimorphic in juvenile alligators and whether living in a contaminated environment affects hepatic dimorphism. Lake Woodruff served as our reference site. Moonshine Bay, ...

  14. Seismic properties and effects of hydrothermal alteration on Volcanogenic Massive Sulfide (VMS) deposits at the Lalor Lake in Manitoba, Canada

    NASA Astrophysics Data System (ADS)

    Miah, Khalid H.; Bellefleur, Gilles; Schetselaar, Ernst; Potter, David K.

    2015-12-01

    Borehole sonic and density logs are essential for mineral exploration at depth, but its limited availability to link rock properties of different ore forming geologic structure is a hindrance to seismic data interpretations. In situ density and velocity logs provide first order control on the reflectivity of various lithologic units. We analyzed borehole logs from 12 drill holes over and around the Lalor VMS deposits geographically located in the northern Manitoba, Canada, in an attempt to characterize lithologic units based on its seismic properties. The Lalor Lake deposit is part of the Paleoproterozoic Flin Flon Belt, and associated with an extensive hydrothermal alteration system. Volcanogenic Massive Sulfide (VMS) zones are distributed in several ore lenses with relatively shallower facies comprise solid to solid sulfides, tend to be disseminated or Stringer sulfides, while deeper lenses are gold and silver enriched and occurred in the highly altered footwall region. Our analysis suggests that massive sulfide and diorite have higher acoustic impedance than other rock units, and can produce useful reflection signatures in seismic data. Bivariate distributions of P-wave velocity, density, acoustic impedance and Poisson's ratio in end-member mineral cones were used for qualitative assessment of the extent of alteration of various lithologic units. It can be inferred that hydrothermal alteration has considerably increased P-wave velocity and density of altered argillite and felsic volcanic rocks in comparison to their corresponding unaltered facies. Amphibole, garnet, kyanite, pyrite, sphalerite and staurolite are the dominant end-member alteration minerals affecting seismic rock properties at the VMS site.

  15. Experimental soil warming and cooling alters the partitioning of recent assimilates: evidence from a (14)C-labelling study at the alpine treeline.

    PubMed

    Ferrari, A; Hagedorn, F; Niklaus, P A

    2016-05-01

    Despite concerns about climate change effects on ecosystems functioning, little is known on how plant assimilate partitioning changes with temperature. Particularly, large temperature effects might occur in cold ecosystems where critical processes are at their temperature limit. In this study, we tested temperature effects on carbon (C) assimilate partitioning in a field experiment at the alpine treeline. We warmed and cooled soils of microcosms planted with Pinus mugo or Leucanthemopsis alpina, achieving daily mean soil temperatures (3-10 cm depth) around 5.8, 12.7 and 19.2 °C in cooled, control and warmed soils. We pulse-labelled these systems with (14)CO2 for one photoperiod and traced (14)C over the successive 4 days. Plant net (14)C uptake increased steadily with soil temperature. However, (14)C amounts in fungal hyphae, soil microbial biomass, soil organic matter, and soil respiration showed a non-linear response to temperature. This non-linear pattern was particularly pronounced in P. mugo, with five times higher (14)C activities in cooled compared to control soils, but no difference between warmed and control soil. Autoradiographic analysis of the spatial distribution of (14)C in soils indicated that temperature effects on the vertical label distribution within soils depended on plant species. Our results show that plant growth, in particular root metabolism, is limited by low soil temperature. As a consequence, positive temperature effects on net C uptake may not be paralleled by similar changes in rhizodeposition. This has important implications for predictions of soil C storage, because rhizodeposits and plant biomass vary strongly in their residence times. PMID:26314342

  16. Falling phytoplankton: altered access to the photic zone over 60 years of warming in Lake Baikal, Siberia

    NASA Astrophysics Data System (ADS)

    Hampton, S. E.; Izmest'eva, L. R.; Moore, M.; Katz, S. L.

    2011-12-01

    Vertical stratification of aquatic ecosystems can be strongly reinforced by long-term warming, altering access to suitable habitat differentially across plankton taxa. Surface waters in the world's most voluminous freshwater lake - Lake Baikal in Siberia - are warming at an average rate of 2.01°C century-1, with more dramatic warming in the summer (3.78°C century-1). This long-term warming trend occurs within seasonal cycles of freezing and thawing, and against the larger backdrop of shorter-term climate dynamics, such as those associated with the Pacific Decadal Oscillation and Arctic Oscillation, with which shifting Siberian weather patterns affect the timing of seasonal changes (e.g., stratification) at the lake. While the increasing temperature difference between surface and deeper waters implies stronger stratification in the summer in general, the available long-term temperature data are not sufficiently fine-scaled across depth to further resolve stratification patterns. However, analysis of long-term vertical phytoplankton distributions may give perspectives on the dynamics of the physical environment that plankton experience. For example, many of Lake Baikal's endemic, cold-adapted phytoplankton species are large and heavy diatoms that require strong mixing to remain suspended, a process that is suppressed by stronger summer stratification. Observed vertical patterns of algal distribution are consistent with the predictions of increased warming and intensified stratification with diatoms present in summer increasingly sinking far beyond the photic zone. Specifically, the average depth of diatoms in August, the most reliably stratified month at Lake Baikal, has increased from depths roughly aligned with photic zone (0.1% light penetration) limits (ca. 40 m) in the 1970s to average depths approximately 48 m below the photic zone by the end of the century. Concurrently, smaller motile algae such as cryptomonads have maintained or increased their presence in

  17. Effects of Short-Term Thermal Alteration on Organic Matter in Experimentally-Heated Tagish Lake Observed by Raman Spectroscopy

    NASA Technical Reports Server (NTRS)

    Chan, Q. H. S.; Nakato, A.; Zolensky, M. E.; Nakamura, T.; Kebukawa, Y.

    2007-01-01

    Carbonaceous chondrites exhibit a wide range of aqueous and thermal alteration characteristics. Examples of the thermally metamorphosed carbonaceous chondrites (TMCCs) include the C2-ung/CM2TIVs Belgica (B)-7904 and Yamato (Y) 86720. The alteration extent is the most complete in these meteorites and thus they are considered typical end-members of TMCCs exhibiting complete dehydration of matrix phyllosilicates [1, 2]. The estimated heating conditions are 10 to 10(sup 3) days at 700 C to 1 to 100 hours at 890 C, i.e. short-term heating induced by impact and/or solar radiation [3]. The chemical and bulk oxygen isotopic compositions of the matrix of the carbonate (CO3)-poor lithology of the Tagish Lake (hereafter Tag) meteorite bears similarities to these TMCCs [4]. We investigated the experimentally-heated Tag with the use of Raman spectroscopy to understand how short-term heating affects the maturity of insoluble organic matter (IOM) in aqueously altered meteorites.

  18. Asynchronous evolution of the isotopic composition and amount of precipitation in north China during the Holocene revealed by a record of compound-specific carbon and hydrogen isotopes of long-chain n-alkanes from an alpine lake

    NASA Astrophysics Data System (ADS)

    Rao, Zhiguo; Jia, Guodong; Li, Yunxia; Chen, Jianhui; Xu, Qinghai; Chen, Fahu

    2016-07-01

    Both the timing of the maximum East Asian summer monsoon (EASM) intensity in monsoonal China and the environmental significance of the Chinese stalagmite oxygen isotopic record (δ18O) have been debated. Here, we present a ca. 120-year-resolution compound-specific carbon (δ13C) and hydrogen (δD) isotopes of terrestrial long-chain n-alkanes extracted from a well-dated sediment core from an alpine lake in north China. Our δ13C data, together with previously reported pollen data from a parallel core, demonstrate a humid mid-Holocene from ca. 8-5 ka BP. Assuming that the climatic humidity of north China is an indicator of the EASM intensity, then the maximum EASM intensity occurred in the mid-Holocene. Our δD data reveal a similar long-term trend to the δ18O record from nearby Lianhua Cave, indicating that the synchronous δD and δ18O records faithfully record the δD and δ18O of precipitation, respectively. The most negative δD and δ18O values occur in the early-mid Holocene, from ca. 11-5 ka BP. This contrast in the timing of isotopic variations demonstrates a complex relationship between the isotopic composition of precipitation and precipitation amount, or EASM intensity. Further comparisons indicate a possible linkage between the precipitation amount in north China and the west-east thermal gradient in the equatorial Pacific. In addition, the temperature of the moisture source area may play an important role in determining the isotopic composition of precipitation in monsoonal China.

  19. Rapid Ecological Change in Two Contrasting Lake Ecosystems: Evidence of Threshold Responses, Altered Species Dynamics, and Perturbed Patterns of Variability

    NASA Astrophysics Data System (ADS)

    Simpson, G. L.

    2015-12-01

    Studying threshold responses to environmental change is often made difficult due to the paucity of monitoring data prior to and during change. Progress has been made via theoretical models of regime shifts or experimental manipulation but natural, real world, examples of threshold change are limited and in many cases inconclusive. Lake sediments provide the potential to examine abrupt ecological change by directly observing how species, communities, and biogeochemical proxies responded to environmental perturbation or recorded ecosystem change. These records are not problem-free; age uncertainties, uneven and variable temporal resolution, and time-consuming taxonomic work all act to limit the scope and scale of the data or complicate its analysis. Here I use two annually laminated records 1. Kassjön, a seasonally anoxic mesotrophic lake in N Sweden, and2. Baldeggersee, a nutrient rich, hardwater lake on the central Swiss Plateau to investigate lake ecosystem responses to abrupt environmental change using ideal paleoecological time series. Rapid cooling 2.2kyr ago in northern Sweden significantly perturbed the diatom community of Kassjön. Using wavelet analysis, this amelioration in climate also fundamentally altered patterns of variance in diatom abundances, suppressing cyclicity in species composition that required several hundred years to reestablish. Multivariate wavelet analysis of the record showed marked switching between synchronous and asynchronous species dynamics in response to rapid climatic cooling and subsequent warming. Baldeggersee has experienced a long history of eutrophication and the diatom record has been used as a classic illustration of a regime shift in response to nutrient loading. Time series analysis of the record identified some evidence of a threshold-like response in the diatoms. A stochastic volatility model identified increasing variance in composition prior to the threshold, as predicted from theory, and a switch from compensatory

  20. Hydrochemical Response to Drought Conditions at an Alpine Watershed, Colorado Front Range

    NASA Astrophysics Data System (ADS)

    Hill, K. R.; Williams, M. W.; Caine, N.; Janke, J. R.; Hartman, M. D.

    2007-12-01

    Extreme climate events play a key role in alpine hydrochemistry by altering source waters and flowpaths. Persistent drought conditions from 2000-2002 at Green Lakes Valley resulted in precipitation and streamflow about 75% of normal for the last 25 years. Surprisingly, both concentrations and fluxes of geochemical weathering products and nutrients increased during the drought at the higher elevation sites. Niwot Ridge LTER has continuously monitored streamflow, precipitation chemistry, and water quality for 25 years in Green Lakes Valley at 8 sites representing an elevation gradient extending from 3250 meters at the valley outlet to 4000 meters at the continental divide. Comparing continuous 5-year blocks of above-average precipitation (1993-1997) vs. below-average years (2000- 2004), both concentrations and fluxes were significantly higher during drought for base cations (p<0.05) throughout upper Green Lakes Valley. DAYCENT modeled predicted discharge correctly during the period of above-average precipitation but underpredicted discharge during drought conditions, suggesting an additional source of water. End Member Mixing Analyses (EMMA) conducted during 1996 constrains streamflow as a mixture of snowmelt, talus water, and groundwater with subsurface flowpaths contributing more than 50% of streamflow, even during snowmelt (Liu, 2004). However, EMMA results during drought years using chemical and isotopic compositions from surface water, talus springs, snowpits, snowmelt, soil water, and groundwater suggest an additional, unidentified source of streamflow. One possible end member is melting permafrost within the basin. We downscaled a qualitative, regional permafrost distribution model of the Colorado Front Range to investigate the potential role of melting permafrost on hydrochemical characteristics in Green Lakes Valley. Model results indicate that increasing mean annual air temperature by 1 degree Celsius results could melt 35% of permafrost in the watershed

  1. CO2 enrichment alters diurnal stem radius fluctuations of 36-yr-old Larix decidua growing at the alpine tree line.

    PubMed

    Dawes, Melissa A; Zweifel, Roman; Dawes, Nicholas; Rixen, Christian; Hagedorn, Frank

    2014-06-01

    To understand how trees at high elevations might use water differently in the future, we investigated the effects of CO2 enrichment and soil warming (separately and combined) on the water relations of Larix decidua growing at the tree line in the Swiss Alps. We assessed diurnal stem radius fluctuations using point dendrometers and applied a hydraulic plant model using microclimate and soil water potential data as inputs. Trees exposed to CO2 enrichment for 9 yr showed smaller diurnal stem radius contractions (by 46 ± 16%) and expansions (42 ± 16%) compared with trees exposed to ambient CO2 . Additionally, there was a delay in the timing of daily maximum (40 ± 12 min) and minimum (63 ± 14 min) radius values for trees growing under elevated CO2 . Parameters optimized with the hydraulic model suggested that CO2 -enriched trees had an increased flow resistance between the xylem and bark, representing a more buffered water supply system. Soil warming did not alter diurnal fluctuation dynamics or the CO2 response. Elevated CO2 altered the hydraulic water flow and storage system within L. decidua trees, which might have contributed to enhanced growth during 9 yr of CO2 enrichment and could ultimately influence the future competitive ability of this key tree-line species. PMID:24571288

  2. Evidence for Impact-induced Hydrothermal Alteration at the Lonar Crater, India, and Mistastin Lake, Canada

    NASA Technical Reports Server (NTRS)

    Newsom, H. E.; Hagerty, J. J.

    2003-01-01

    The 50,000 year old, 1.8km diameter Lonar crater is located in Maharashtra, India. This relatively small crater is of particular interest because of its unique morphological and mineralogical properties, which make it a valid analogue for similar craters on the surface of Mars. We show that even in this relatively small crater, substantial hydrothermal alteration of shocked breccias in the floor of the crater has occurred, probably due to the thermal effects of the impact event. The 38 my old, 28 km diameter, Mistastin crater contains an 80 m thick impact melt sheet. We have also documented the presence of alteration phases in the material from this larger crater.

  3. Chemical Compositional Indications of Aqueous Alteration for Whitewater Lake Boxworks, Veneers and Veins at Cape York, Mars

    NASA Astrophysics Data System (ADS)

    Clark, Benton; Gellert, R.; Squyres, S.; Arvidson, R.; Yen, A.; Rice, J.; Athena Science Team

    2013-10-01

    An area of partially-veneered, flat-lying rocks which also includes boxwork and linear veins contains a variety of compositions which are each indicative of minor to major aqueous alteration processes in the Cape York rim of Endeavour Crater. As analyzed by APXS x-ray fluorescence spectroscopy, the sets of unique elemental compositions correspond variously to Al-Si rich clays in boxwork veins, with Fe- and Cl-enriched salt veneers (Esperance samples); swarms of Ca sulfate veins (Ortiz samples); and, as indicated by remote sensing, mafic smectite alteration products in veneers (Chelmsford covering Azilda samples). Multiple offset analyses by APXS reveal clear trends and associations of certain elements, allowing inferences of mineralogies. In contrast to the acidic environment deduced for the genesis of the multiple-sulfate Burns formation sediments and shallow ferric-rich sulfate deposits beneath soils, these alteration products formed at more near-neutral pH, often with major chemical segregations and requiring high water-rock ratios comparable to a wide range of eminently habitable terrestrial environments. Several of these compositions are also rated high with respect to their potential for preservation of organic materials and biomarkers. Within distances of just tens of meters inside this so-called Whitewater Lake unit, this broad diversity exemplifies the tantalizing opportunities as well as challenges for future sample return missions to the red planet, which in this case could also be expanded to include nearby samples of Burns Fm sandstones, hematite concretions, light-toned spherules (Kirkwood), large gypsum veins (Homestake), martian global soils and surface dust.

  4. Dynamic hypoxic zones in Lake Erie compress fish habitat, altering vulnerability to fishing gears

    USGS Publications Warehouse

    Kraus, Richard T.; Knight, Carey T.; Farmer, Troy M.; Gorman, Ann Marie; Collingsworth, Paris D.; Warren, Glenn J.; Kocovsky, Patrick M.; Conroy, Joseph D.

    2015-01-01

    Seasonal degradation of aquatic habitats from hypoxia occurs in numerous freshwater and coastal marine systems and can result in direct mortality or displacement of fish. Yet, fishery landings from these systems are frequently unresponsive to changes in the severity and extent of hypoxia, and population-scale effects have been difficult to measure except in extreme hypoxic conditions with hypoxia-sensitive species. We investigated fine-scale temporal and spatial variability in dissolved oxygen in Lake Erie as it related to fish distribution and catch efficiencies of both active (bottom trawls) and passive (trap nets) fishing gears. Temperature and dissolved oxygen loggers placed near the edge of the hypolimnion exhibited much higher than expected variability. Hypoxic episodes of variable durations were frequently punctuated by periods of normoxia, consistent with high-frequency internal waves. High-resolution interpolations of water quality and hydroacoustic surveys suggest that fish habitat is compressed during hypoxic episodes, resulting in higher fish densities near the edges of hypoxia. At fixed locations with passive commercial fishing gear, catches with the highest values occurred when bottom waters were hypoxic for intermediate proportions of time. Proximity to hypoxia explained significant variation in bottom trawl catches, with higher catch rates near the edge of hypoxia. These results emphasize how hypoxia may elevate catch rates in various types of fishing gears, leading to a lack of association between indices of hypoxia and fishery landings. Increased catch rates of fish at the edges of hypoxia have important implications for stock assessment models that assume catchability is spatially homogeneous.

  5. Regulation of the KNOX-GA Gene Module Induces Heterophyllic Alteration in North American Lake Cress[W

    PubMed Central

    Nakayama, Naomi; Seiki, Sumer; Kojima, Mikiko; Sakakibara, Hitoshi

    2014-01-01

    Plants show leaf form alteration in response to changes in the surrounding environment, and this phenomenon is called heterophylly. Although heterophylly is seen across plant species, the regulatory mechanisms involved are largely unknown. Here, we investigated the mechanism underlying heterophylly in Rorippa aquatica (Brassicaceae), also known as North American lake cress. R. aquatica develops pinnately dissected leaves in submerged conditions, whereas it forms simple leaves with serrated margins in terrestrial conditions. We found that the expression levels of KNOTTED1-LIKE HOMEOBOX (KNOX1) orthologs changed in response to changes in the surrounding environment (e.g., change of ambient temperature; below or above water) and that the accumulation of gibberellin (GA), which is thought to be regulated by KNOX1 genes, also changed in the leaf primordia. We further demonstrated that exogenous GA affects the complexity of leaf form in this species. Moreover, RNA-seq revealed a relationship between light intensity and leaf form. These results suggest that regulation of GA level via KNOX1 genes is involved in regulating heterophylly in R. aquatica. The mechanism responsible for morphological diversification of leaf form among species may also govern the variation of leaf form within a species in response to environmental changes. PMID:25516600

  6. Pseudotachylyte and Fluid Alteration at Seismogenic Depths (Glacier Lakes and Granite Pass Faults, Central Sierra Nevada, USA)

    NASA Astrophysics Data System (ADS)

    Prante, Mitchell R.; Evans, James P.

    2015-05-01

    We present evidence for ancient seismicity in the form of tectonic pseudotachylyte and coeval, cyclic hydrothermal alteration, and cataclasis along fault zones exhumed from 2.4 to 6.0 km in the central Sierra Nevada, CA. The Glacier Lakes fault (GLF) and Granite Pass fault (GPF) are exhumed left-lateral to left-lateral oblique, strike-slip faults with up to 125 m of left-lateral separation exposed in Mesozoic granite and granodiorite plutons. Precipitation of epidote along fault slip-surfaces, chloritization of biotite, saussurite and sericite alteration of plagioclase, and quartz- and-calcite filled veins are present in the GLF and GPF zones. One difficulty encountered in studying exhumed fault zones is providing convincing evidence for a frictional melt origin of pseudotachylyte. Rocks in the field may preserve convincing evidence for frictional melt (i.e., aphanitic, dark, injection structures) that are later shown to be related to cataclasis or injection of hydrothermal fluids. Another challenge results from the low preservation potential of several of the microscopic features that are convincing evidence of a frictional melt origin (microlites, amygdules, and glassy matrix). Here we test the usefulness of grain shape and nearest neighbor distribution analysis of pseudotachylyte and cataclasites from the GLF and GPF to discriminate between these fault rocks and to determine a frictional melt origin for pseudotachylyte. Fabric analyses of the clasts within the pseudotachylytes examined are more circular and exhibit a random nearest neighbor clast distribution relative to adjacent cataclasites. With increased comminution and melting the mean clast circularity increases and the nearest neighbor distances approach a random distribution. We conclude that this observed pattern can be applied to other fault zones as an indicator of a frictional melt origin for fault-related rocks. Mutually cross-cutting zones of hydrothermal alteration and calcite deformation twins

  7. The altered ecology of Lake Christina: a record of regime shifts, land-use change, and management from a temperate shallow lake.

    PubMed

    Theissen, Kevin M; Hobbs, William O; Hobbs, Joy M Ramstack; Zimmer, Kyle D; Domine, Leah M; Cotner, James B; Sugita, Shinya

    2012-09-01

    We collected two sediment cores and modern submerged aquatic plants and phytoplankton from two sub-basins of Lake Christina, a large shallow lake in west-central Minnesota, and used stable isotopic and elemental proxies from sedimentary organic matter to explore questions about the pre- and post-settlement ecology of the lake. The two morphologically distinct sub-basins vary in their sensitivities to internal and external perturbations offering different paleoecological information. The record from the shallower and much larger western sub-basin reflects its strong response to internal processes, while the smaller and deeper eastern sub-basin record primarily reflects external processes including important post-settlement land-use changes in the area. A significant increase in organic carbon accumulation (3-4 times pre-settlement rates) and long-term trends in δ(13)C, organic carbon to nitrogen ratios (C/N), and biogenic silica concentrations shows that primary production has increased and the lake has become increasingly phytoplankton-dominated in the post-settlement period. Significant shifts in δ(15)N values reflect land-clearing and agricultural practices in the region and support the idea that nutrient inputs have played an important role in triggering changes in the trophic status of the lake. Our examination of hydroclimatic data for the region over the last century suggests that natural forcings on lake ecology have diminished in their importance as human management of the lake increased in the mid-1900s. In the last 50 years, three chemical biomanipulations have temporarily shifted the lake from the turbid, algal-dominated condition into a desired clear water regime. Two of our proxies (δ(13)C and BSi) measured from the higher resolution eastern basin record responded significantly to these known regime shifts. PMID:22819884

  8. Relevance of wet deposition of organic matter for alpine ecosystems

    NASA Astrophysics Data System (ADS)

    Mladenov, N.; Williams, M. W.; Schmidt, S. K.; Goss, N. R.; Reche, I.

    2011-12-01

    In barren, alpine environments, carbon inputs from atmospheric deposition may be very important for ecological processes. Recent findings suggest that atmospheric deposition influences the quality of dissolved organic matter (DOM) in alpine lakes on a global scale. Here, we evaluate the inputs of DOM in atmospheric wet deposition to alpine terrestrial ecosystems, in terms of both quantity and quality. We show that at the Niwot Ridge Long Term Ecological Research Station (Colorado, USA) wet deposition represents a seasonally variable (Figure 1) mass input of organic carbon, depositing on average 6 kg C/ha/yr or roughly 1500 kg C to the Green Lake 4 watershed at Niwot Ridge. Wet deposition is, therefore, a substantial input of dissolved organic carbon (DOC) to the catchment when compared to the annual DOC yield from Green Lake 4, estimated at just over 1800 kg C. In terms of DOM bioavailability for alpine microorganisms, our optical spectroscopic results showing high amounts of amino acid-like fluorescence and low aromaticity suggest that DOM in wet deposition may be particularly labile, especially in the summer months. The heterotrophic processing of this organic carbon input has important implications for the cycling of other nutrients, such as nitrogen, in alpine environments. We have also shown that the sources of DOM in wet deposition include bioaerosols, such as pollen, which represent much of the summer DOC loading. However, relationships with inorganic N and sulfate also suggest that organic pollutants in the atmosphere may have an equally important influence on DOM in wet deposition. Additionally, the quality of wet deposition DOM in the spring is similar to that of dust deposition observed near the Sahara and may be influenced by dust events, as shown from air mass trajectories originating in or near the Colorado Plateau. The seasonality of DOM quality appears to be related to these varying sources and is, therefore, a critical topic for future research.

  9. [Impacts of Ochotona pallasi disturbance on alpine grassland community characteristics].

    PubMed

    Zhao, Guo-qin; Li, Guang-yong; Ma, Wen-hu; Zhao, Dian-zhi; Li, Xiao-yan

    2013-08-01

    Plateau pika is the main fossorial mammal in the alpine grassland in Qinghai Lake Watershed of Northwest China. Based on the field investigation data from 18 alpine grassland quadrats in the Watershed, and by using redundancy analysis (RDA) and the surface fitting offered by 'R-Vegan' , the disturbance intensity of plateau pika (Ochotona pallasi) was classified as four levels. In order to explore the impacts of plateau pika disturbance on the alpine grassland ecosystem and its grazing quality, the community characteristics under different disturbance intensities by plateau pika were analyzed, and a conceptual model about the alpine grassland community succession was proposed. The results showed that with the increase of the disturbance intensity, the dominant species changed from Juncus roemerianus to Poa pratensis and Laux maritima. When the disturbance was small, the community had high quantitative values of coverage, aboveground biomass, biodiversity, and species richness, but the proportion of weeds was also high. When the disturbance was large, the quantitative values were the lowest, while the proportion of weeds was the highest. When the disturbance was moderate, the community had relatively high quantitative values, and the proportion of grasses and sedges was the highest. It was concluded that the community' s characteristic values under low plateau pika disturbance intensity were high but the grazing quality was low, while high disturbance intensity resulted in the grassland degradation. Therefore, the disturbance intensity in the threshold could maintain the stability of alpine grassland ecosystem and improve its grazing quality. PMID:24380328

  10. Ecosystem Alterations and Species Range Shifts: An Atlantic-Mediterranean Cephalaspidean Gastropod in an Inland Egyptian Lake.

    PubMed

    Cruz-Rivera, Edwin; Malaquias, Manuel António E

    2016-01-01

    The eastern Atlantic and Mediterranean marine Cephalaspidea gastropod Haminoea orbignyana was collected from Lake Qarun (Fayoum, Egypt), a landlocked lake that has undergone a shift from freshwater to estuarine conditions in the past 100 years. Species identity was confirmed by both morphological (anatomical dissection and scanning electron microscopy) and molecular methods (COI gene phylogeny). Observations suggested a robust population of H. orbignyana in the lake with a density of ca. 64 individuals/m2 and ca. 105 egg masses/m2 during surveys conducted in the summer of 2013. The vast majority of snails and egg masses were found under rocks. Observations of egg masses in the lab showed a gradual change from whitish to yellow-green as the eggs matured and the release of veliger larvae alone after about a week. Although adult cephalaspideans readily consumed filamentous red and green algae, and cyanobacteria, laboratory trials showed that they consumed significantly more of the red alga Ceramium sp., than of the green alga Cladophora glomerata, with consumption of Oscillatoria margaritifera being similar to those on the two algae. When grown on these resources for 16 days, H. orbignyana maintained their mass on the rhodophyte and cyanobacterium, but not in starvation controls. No cephalaspideans grew over the course of this experiment. Lake Qarun has been periodically restocked with Mediterranean fishes and prawns since the 1920s to maintain local fisheries, which represents a possible route of colonization for H. orbignyana. Yet, based on literature records, it seems more likely that invasion of the lake by this gastropod species has occurred only within the last 20 years. As human activities redistribute species through direct and indirect means, the structure of the community of this inland lake has become unpredictable and the long-term effects of these recent introductions are unknown. PMID:27248835

  11. Ecosystem Alterations and Species Range Shifts: An Atlantic-Mediterranean Cephalaspidean Gastropod in an Inland Egyptian Lake

    PubMed Central

    Malaquias, Manuel António E.

    2016-01-01

    The eastern Atlantic and Mediterranean marine Cephalaspidea gastropod Haminoea orbignyana was collected from Lake Qarun (Fayoum, Egypt), a landlocked lake that has undergone a shift from freshwater to estuarine conditions in the past 100 years. Species identity was confirmed by both morphological (anatomical dissection and scanning electron microscopy) and molecular methods (COI gene phylogeny). Observations suggested a robust population of H. orbignyana in the lake with a density of ca. 64 individuals/m2 and ca. 105 egg masses/m2 during surveys conducted in the summer of 2013. The vast majority of snails and egg masses were found under rocks. Observations of egg masses in the lab showed a gradual change from whitish to yellow-green as the eggs matured and the release of veliger larvae alone after about a week. Although adult cephalaspideans readily consumed filamentous red and green algae, and cyanobacteria, laboratory trials showed that they consumed significantly more of the red alga Ceramium sp., than of the green alga Cladophora glomerata, with consumption of Oscillatoria margaritifera being similar to those on the two algae. When grown on these resources for 16 days, H. orbignyana maintained their mass on the rhodophyte and cyanobacterium, but not in starvation controls. No cephalaspideans grew over the course of this experiment. Lake Qarun has been periodically restocked with Mediterranean fishes and prawns since the 1920s to maintain local fisheries, which represents a possible route of colonization for H. orbignyana. Yet, based on literature records, it seems more likely that invasion of the lake by this gastropod species has occurred only within the last 20 years. As human activities redistribute species through direct and indirect means, the structure of the community of this inland lake has become unpredictable and the long-term effects of these recent introductions are unknown. PMID:27248835

  12. Heat-Wave Effects on Oxygen, Nutrients, and Phytoplankton Can Alter Global Warming Potential of Gases Emitted from a Small Shallow Lake.

    PubMed

    Bartosiewicz, Maciej; Laurion, Isabelle; Clayer, François; Maranger, Roxane

    2016-06-21

    Increasing air temperatures may result in stronger lake stratification, potentially altering nutrient and biogenic gas cycling. We assessed the impact of climate forcing by comparing the influence of stratification on oxygen, nutrients, and global-warming potential (GWP) of greenhouse gases (the sum of CH4, CO2, and N2O in CO2 equivalents) emitted from a shallow productive lake during an average versus a heat-wave year. Strong stratification during the heat wave was accompanied by an algal bloom and chemically enhanced carbon uptake. Solar energy trapped at the surface created a colder, isolated hypolimnion, resulting in lower ebullition and overall lower GWP during the hotter-than-average year. Furthermore, the dominant CH4 emission pathway shifted from ebullition to diffusion, with CH4 being produced at surprisingly high rates from sediments (1.2-4.1 mmol m(-2) d(-1)). Accumulated gases trapped in the hypolimnion during the heat wave resulted in a peak efflux to the atmosphere during fall overturn when 70% of total emissions were released, with littoral zones acting as a hot spot. The impact of climate warming on the GWP of shallow lakes is a more complex interplay of phytoplankton dynamics, emission pathways, thermal structure, and chemical conditions, as well as seasonal and spatial variability, than previously reported. PMID:27266257

  13. Multiple Waterspouts at Lake Tahoe.

    NASA Astrophysics Data System (ADS)

    Grotjahn, Richard

    2000-04-01

    At least six waterspouts occurred at a large alpine lake in the western United States over several hours during 26 September 1998. Photographs showing the conditions as well as representative examples of this extremely rare event are presented. Some mechanisms are discussed that may explain the persistence of the convection and the low-level vorticity that gave rise to the waterspouts.

  14. Endocrine disruption and altered gonadal development in white perch (Morone americana) from the lower Great Lakes region.

    PubMed Central

    Kavanagh, Richard J; Balch, Gordon C; Kiparissis, Yiannis; Niimi, Arthur J; Sherry, Jim; Tinson, Cheryl; Metcalfe, Chris D

    2004-01-01

    High prevalences of gonadal intersex have been observed in wild fish populations in areas affected by domestic and industrial effluents. For this study, fish were collected in 1998 from the Cootes Paradise region of Hamilton Harbour in western Lake Ontario, Canada, to determine whether gonadal abnormalities, including intersex, were present in young of the year (YOY) fish. No gonadal abnormalities were observed in goldfish (Carassius auratus), common carp (Cyprinus carpio), gizzard shad (Dorosoma cepedianum), brown bullhead (Ictalurus ameiurus), pumpkinseed (Lepomis gibbosus), and bluegill (Lepomis macrochirus). However, intersex gonads were observed in 8 of 16 male white perch (Morone americana) examined in this survey. Subsequently, in 1999 and 2000 white perch estimated to be YOY to approximately 2 years of age were collected from Cootes Paradise and from two other sites in the lower Great Lakes region. Gonadal intersex was observed in male white perch collected from the Bay of Quinte (22-44%) and Lake St. Clair (45%), although the prevalence and the extent of the intersex condition were lower relative to the 83% prevalence in white perch collected in Cootes Paradise. Intersex was not observed in hatchery-reared white perch or in white perch collected from an uncontaminated reference site (i.e., Deal Lake) in the United States. An analysis of plasma collected in the spring of 2002 from male adult white perch in Cootes Paradise revealed high concentrations of vitellogenin, ranging from 49 to 1,711 microg/mL. These observations indicate that male white perch are exposed to estrogenic endocrine-disrupting substances that may be responsible for the induction of gonadal intersex. PMID:15175179

  15. Enrichment of Non-Terrestrial L-Proteinogenic Amino Acids by Aqueous Alteration on the Tagish Lake Meteorite Parent Body

    NASA Technical Reports Server (NTRS)

    Glavin, Daniel P.; Elsila, Jamie E.; Burton, Aaron S.; Callahan, Michael P.; Dworkin, Jason P.; Herd, Christopher D. K.

    2012-01-01

    The distribution and isotopic and enantiomeric compositions of amino acids found in three distinct fragments of the Tagish Lake C2-type carbonaceous chondrite were investigated via liquid chromatography fluorescence detection time-of-flight mass spectrometry and gas chromatography isotope ratio mass spectrometry. Large L-enantiomeric excesses (L(sub ee) approx. 43 to 59%) of the a-hydrogen aspartic and glutamic amino acids were measured in Tagish Lake, whereas alanine, another alpha-hydrogen protein amino acid, was found to be nearly racemic (D approx. L) using both techniques. Carbon isotope measurements of D- and L-aspartic acid and D- and L-alanine in Tagish Lake fall well outside of the terrestrial range and indicate that the measured aspartic acid enantioenrichment is indigenous to the meteorite. Alternate explanations for the Lexcesses of aspartic acid such as interference from other compounds present in the sample, analytical biases, or terrestrial amino acid contamination were investigated and rejected. These results can be explained by differences in the solid-solution phase behavior of aspartic acid, which can form conglomerate enantiopure solids during crystallization, and alanine, which can only form racemic crystals.

  16. Field Trip Guide to Serpentinite, Silica-Carbonate Alteration, and Related Hydrothermal Activity in the Clear Lake Region, California

    SciTech Connect

    Fraser Goff; George Guthrie

    1999-06-01

    This guide is designed to familiarize scientists with the geology, structure, alteration, and fluids typical of California serpentinites for purposes of carbon dioxide sequestration (Lackner et al., 1995). Goff et al. (1997) and Goff and Lackner (1998) describe the geology and geochemistry of some of the serpentinites from this area. Mechanisms of silica-carbonate alteration were outlined by Barnes et al. (1973). Donnelly-Nolan et al. (1993) most recently reviewed relations between regional hydrothermal alteration and Quarternary volcanic activity. Stanley et al. (1998) summarized geophysical characteristics of the region.

  17. Lake surface area variation and its responses to climatic change in Yamzhog Yumco Basin, South Tibet during 1970-2010

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Tian, Y.; Sun, R.

    2015-12-01

    The research on lake extraction from multi-source and multi-temporal satellite images and the lake size variation can provide reliable method and indispensable information to deepen the understanding about alpine lake changes with the accelerating warming. With field survey experience in the Yamzhog Yumco Basin, South Tibet, the outlines of five lakes (i.e., Yamzhog Yumco, Chen Co, Kongmu Co, Bajiu Co and Puma Yumco) were delineated by the adoption of 42 scenes of satellite images from Landsat, CBERS and HJ from 1970 to 2010, basing on which the responses of alpine lakes to climate change at different timescales were explored. The results are summarized as follows. (1) The seasonal fluctuation of lake surface area was similar with different trend for the five alpine lakes. As for the last 41 years, the annual variation of lake surface area exhibited two kinds of patterns for the five alpine lakes. And the Yamzhog Yumco declined by 9.41%, while the rest four lakes expanded. (2) The responses of alpine lakes to climate change rely on different timescale and water replenishment types. On the one hand, the precipitation change was the predominant driving forces for the seasonal fluctuation and variation trend of lake size, and the rising temperature accounted for the inter-annual lake surface variation. On the other hand, the two kinds of alpine lakes behaviors were well correspondent with the warming temperature over the Qinghai-Tibetan Plateau. The lakes supplied mainly by precipitation shrunk as a result of increased evaporation, and lakes supplied mainly by glacier and snow meltwater, however, expanded because of the remarkable glacier recession. (3) The quantification of hydrological components would hopefully be improved, according to uncertainties analysis, with the adoption of microwave satellite images and higher resolution ones to disclose the interaction mechanism among climate, glacier, and lake in alpine regions.

  18. Hydrothermal alteration of organic matter in uranium ores, Elliot Lake, Canada: Implications for selected organic-rich deposits

    SciTech Connect

    Mossman, D.J.; Nagy, B.; Davis, D.W.

    1993-07-01

    Organic matter in the uraniferous Matinenda Formation, Elliot Lake, is preserved in the forms of syngenetic kerogen and solid bitumen as it is in many of the Oklo uranium deposits and in the Witwatersrand gold-uranium ores. The Elliot Lake kerogen is a vitrinite-like material considered to be remnants of the Precambrian cyanobacterial mats. The kerogen at Elliot Lake has reflectances (in oil) ranging from 2.63-7.31% RO{sub max}, high aromaticity, relatively low (0.41-0.60) atomic H/C ratios, and it contains cryptocrystalline graphite. Bitumen, present primarily as dispersed globules (up to 0.5 mm dia.), has reflectances from 0.72-1.32% RO{sub max}, atomic H/C ratios of 0.71-0.81, and is somewhat less aromatic than the kerogen. Overall similarity in molecular compositions indicates that liquid bitumen was derived from kerogen by processes similar to hydrous pyrolysis. The carbon isotopic composition of kerogen ({minus}15.62 to {minus}24.72%), and the now solid bitumen ({minus}25.91 to {minus}33.00%) are compatible with these processes. Despite having been subjected to several thermal episodes, ca. 2.45 Ga old kerogen of microbiological origin here survived as testimony of the antiquity of life on Earth. U-Pb isotopic data from discrete kerogen grains at Elliot Lake form a scattered array intersecting concordia at 2130 {+-} 100 Ma, correspond to the Nipissing event. U-Pb systems were totally reset by this event. Uranium and lead show subsequently partial mobility, the average of which is indicated by the lower concordia intersect of 550 {+-} 260 Ma. The migrated bitumen contains virtually no uranium and thorium but has a large excess of {sup 206}Pb, which indicates that the once liquid bitumen must have acted as a sink for mobile intermediate decay products of {sup 238}U. Emplacement of the Nipissing diabase may have been responsible for producing the bitumen and, indirectly, for its enrichment in {sup 206}Pb as a result of outgassing of {sup 222}Rn.

  19. Tapping rocks for Terror Lake hydro project

    SciTech Connect

    Sieber, O.V.

    1983-12-01

    The Terror Lake hydro project in Alaska is described. Terror Lake is a small alpine lake surrounded by barren glacier-scoured, rocky mountain tops and plateaus that do not retain moisture. The method for obtaining more water for the hydro project in Kodiak is unique. The basic program was to dam up the outlet of Terror Lake and raise the water level 170 ft. from approximately 1250 ft. above sea level to 1420 ft. Although the megawatt output of the project is small, the concept of the Terror Lake Project has an epic scale to it.

  20. Fischer-Tropsch synthesis of hydrocarbons during sub-solidus alteration of the Strange Lake peralkaline granite, Quebec/Labrador, Canada

    NASA Astrophysics Data System (ADS)

    Salvi, Stefano; Williams-Jones, Anthony E.

    1997-01-01

    The composition of the carbonic phase(s) of fluid inclusions in pegmatite quartz from the Strange Lake peralkaline complex has been analysed by gas chromatography using online extraction of inclusion contents and a PoraPLOT® Q capillary column. The measured gas species are, in order of abundance, CH 4, H 2, C 2H 6, CO 2, N 2, CA, n-C 4H 10, n-C 5H 12, C 2H 2, i-C 4H 10 and C 2H 4 Minor amounts of i-C 5H 12, n-C 6H 14, i-C 6H 14, and neo-C 6H 14 were also detected (but not quantified) in some samples. A suite of quartz samples from Ca-metasomatised pegmatites contains fluid inclusions with a similar distribution of hydrocarbons but much higher proportions of C0 2. The carbonic fluid coexisted immiscibly with a brine ( Salvi and Williams-Jones, 1992), which on the basis of field and petrographic evidence, was interpreted to have originated from the magma. However, thermodynamic calculations indicate that the above gas species, specifically the hydrocarbons, could not have coexisted at equilibrium in the proportions measured, at any geologically reasonable conditions either prior to or post entrapment. We propose, instead, that the gas compositions measured in the Strange Lake inclusions, and in inclusions from other alkalic complexes, resulted from the production of H 2 during the alteration of arfvedsonite to aegirine, and the subsequent reaction of this H 2 with orthomagmatic C0 2 and CO to form hydrocarbons in a magnetite-catalysed Fischer-Tropsch synthesis. Locally, influx of an oxidised calcic brine, derived externally from the pluton, altered the original composition of the fluid by converting hydrocarbons to C0 2.

  1. Food Web Topology in High Mountain Lakes

    PubMed Central

    Sánchez-Hernández, Javier; Cobo, Fernando; Amundsen, Per-Arne

    2015-01-01

    Although diversity and limnology of alpine lake systems are well studied, their food web structure and properties have rarely been addressed. Here, the topological food webs of three high mountain lakes in Central Spain were examined. We first addressed the pelagic networks of the lakes, and then we explored how food web topology changed when benthic biota was included to establish complete trophic networks. We conducted a literature search to compare our alpine lacustrine food webs and their structural metrics with those of 18 published lentic webs using a meta-analytic approach. The comparison revealed that the food webs in alpine lakes are relatively simple, in terms of structural network properties (linkage density and connectance), in comparison with lowland lakes, but no great differences were found among pelagic networks. The studied high mountain food webs were dominated by a high proportion of omnivores and species at intermediate trophic levels. Omnivores can exploit resources at multiple trophic levels, and this characteristic might reduce competition among interacting species. Accordingly, the trophic overlap, measured as trophic similarity, was very low in all three systems. Thus, these alpine networks are characterized by many omnivorous consumers with numerous prey species and few consumers with a single or few prey and with low competitive interactions among species. The present study emphasizes the ecological significance of omnivores in high mountain lakes as promoters of network stability and as central players in energy flow pathways via food partitioning and enabling energy mobility among trophic levels. PMID:26571235

  2. Food Web Topology in High Mountain Lakes.

    PubMed

    Sánchez-Hernández, Javier; Cobo, Fernando; Amundsen, Per-Arne

    2015-01-01

    Although diversity and limnology of alpine lake systems are well studied, their food web structure and properties have rarely been addressed. Here, the topological food webs of three high mountain lakes in Central Spain were examined. We first addressed the pelagic networks of the lakes, and then we explored how food web topology changed when benthic biota was included to establish complete trophic networks. We conducted a literature search to compare our alpine lacustrine food webs and their structural metrics with those of 18 published lentic webs using a meta-analytic approach. The comparison revealed that the food webs in alpine lakes are relatively simple, in terms of structural network properties (linkage density and connectance), in comparison with lowland lakes, but no great differences were found among pelagic networks. The studied high mountain food webs were dominated by a high proportion of omnivores and species at intermediate trophic levels. Omnivores can exploit resources at multiple trophic levels, and this characteristic might reduce competition among interacting species. Accordingly, the trophic overlap, measured as trophic similarity, was very low in all three systems. Thus, these alpine networks are characterized by many omnivorous consumers with numerous prey species and few consumers with a single or few prey and with low competitive interactions among species. The present study emphasizes the ecological significance of omnivores in high mountain lakes as promoters of network stability and as central players in energy flow pathways via food partitioning and enabling energy mobility among trophic levels. PMID:26571235

  3. Tourism and Water: Themes of the Alpine Convention

    NASA Astrophysics Data System (ADS)

    Imhof, R.

    2012-04-01

    environment. This needs to be accomplished by balancing the local population's interests with environmental needs. Water is considered as a crucial element for different uses such as hydroelectricity production, irrigation or drinking water as well as in biotopes, especially forests, environmental regeneration and diversity and in natural and cultural landscapes features. Aspects of water protection can be found in the protocols on Energy, Nature Conservation and Landscape Protection, Soil Protection, Tourism, Spatial Planning and Sustainable Development, Mountain Agriculture, Mountain Forests and Transport. However a specific protocol on water is not in place. The Reports on the state of the Alps are published regularly by the Alpine Conference. In November 2006 water was chosen as the topic for the second Report on the State of the Alps. The report compiles information from the Alpine Countries on monitoring programmes, chemical quality of water (point sources, diffuse sources and the chemical status of surface and groundwater in the Alps), water abstraction, residual water and hydro-peaking, droughts and water scarcity, reservoirs and regulated lakes as well on river morphology and continuity. Finally, it summarizes information on property rights and provisions for access to water in the different countries, charges regarding the use of water, different management systems for water supply (public or private), hydro power generation in the Alps and water use management conflicts. The Report was adopted by the Ministers during the Xth Alpine Conference in Evian (France) in 2009. This Conference additionally set up a platform on Water management in the Alpine area in order to deal continually with the theme of water in the Alps. Within this platform, objectives that were identified in the second Report on the State of the Alps should be pursued and examples of good practices exchanged. The platform developed inter alia common guidelines for the use of small hydropower in the

  4. Seismic properties of rocks affected by hydrothermal alteration: a case study from the Lalor Lake VMS mining camp

    NASA Astrophysics Data System (ADS)

    Miah, K.; Bellefleur, G.; Schetselaar, E.

    2013-12-01

    Global demand of base metals, uranium, diamonds, and precious metals has been pushing technological barrier to find and extract minerals at higher depth, which was not feasible in just a few decades ago. Seismic properties of rocks containing and surrounding ore bodies have been useful in characterizing and modeling geologic structures, and mapping high-resolution images of ore bodies. Although seismic surveys and drill hole sonic and density logs are essential for mineral exploration at depth, limited availability of seismic logs to link rock properties of different ore forming geologic structure is a hindrance to seismic interpretations. Volcanogenic Massive Sulphides (VMS) are rich in minerals and of primary interests among geologists and mining industries alike. VMS deposits occur due to focused discharge of metal-enriched fluids associated in the hydrothermal alteration process, and are rich in Zn, Cu, Pb, Ag, Au, etc. Alteration halos surrounding ore deposits can be widespread, and their locations are easier to determine than the deposits within them. Physical rock properties affected by alteration can provide clues on type and potentially size of ore deposits in the surrounding area. In this context, variations in seismic properties of rocks due to hydrothermal alteration near the deposits can help in improving modeling accuracy, and better interpretation of seismic data for economic mineral exploration. While reflection seismic techniques can resolve ore bodies at higher depths than other conventional geophysical techniques, they are relatively expensive both in terms of field data acquisition and post-processing, especially for high-resolution 3D surveys. Acoustic impedance contrasts of ore lenses with their hosting rock environment; geometry, size and spatial location relative to the surface affect their detection with seismic data. Therefore, apriori knowledge of seismic rock properties from drill hole logs and core samples in the potential survey area

  5. Application of near surface geophysical methods to image water table response in an Alpine Meadow, Northern California.

    NASA Astrophysics Data System (ADS)

    Ayers, M.; Blacic, T. M.; Craig, M. S.; Yarnell, S. M.

    2015-12-01

    Meadows are recognized for their value to the ecological, hydrologic, and aesthetic functions of a watershed. As natural water retention sinks, meadows attenuate floods, improve water quality and support herbaceous vegetation that stabilize streambanks and promote high biodiversity. Alpine meadows are especially vital, serving as freshwater sources and distributing to lower lying provinces through ground and surface water interaction. These complexes are highly vulnerable to drought conditions, altered seasonal precipitation patterns, and mismanaged land use. One such location, Van Norden meadow located in the Donner Summit area west of Lake Tahoe, is one of the largest sub-alpine meadows in the Sierra Nevada mountain range of Northern California. Van Norden meadow offers a natural hydrologic laboratory. Ownership transfer of the area from a local land trust to the Forestry Service requires restoration toward natural meadow conditions, and involves notching the dam in 2016 to reduce currently impounded water volumes from 250 to less than 50 acre-feet. To monitor the effects of notching the dam on the upstream meadow conditions, better understanding of the surface and groundwater hydrology both pre-and post-base level alteration is required. Comprehensive understanding of groundwater flux that supports meadow reaches relies on knowledge of their often complex stratigraphic and structural subsurface framework. In recent years hydrogeophysics has emphasized the combination of near surface geophysical techniques, collaborated with well and borehole measures, to qualitatively define these parameters. Building on a preliminary GPR investigation conducted in 2014, in which 44 270 MHz transect lines were collected, we returned to Van Norden meadow in late summer 2015 to collect lower frequency GPR (50 and 100 MHz) and electrical resistivity profiles to better define the groundwater table, sedimentary, and structural features of the meadow.

  6. Fischer-Tropsch synthesis of hydrocarbons during sub-solidus alteration of the Strange Lake peralkaline granite, Quebec/Labrador, Canada

    SciTech Connect

    Salvi, S.; Williams-Jones, A.E.

    1997-01-01

    The composition of the carbonic phase(s) of fluid inclusions in pegmatite quartz from the Strange Lake peralkaline complex has been analysed by gas chromatography using online extraction of inclusion contents and a PoraPLOT{reg_sign} Q capillary column. The measured gas species are, in order of abundance, CH{sub 4} H{sub 2}, C{sub 2}H{sub 6}, CO{sub 2}, N{sub 2}, C{sub 3}H{sub 8}, n-C{sub 4}H{sub 10}, n-C{sub 5}H{sub 12}, C{sub 2}H{sub 2}-i-C{sub 4}H{sub 10}, and C{sub 2}H{sub 4}. Minor amounts of i-C{sub 5}H{sub 12}, n-C{sub 6}H{sub 14}, i-C{sub 6}H{sub 14}, and neo-C{sub 6}H{sub 14}, were also detected (but not quantified) in some samples. A suite of quartz samples from Ca-metasomatised pegmatites contains fluid inclusions with a similar distribution of hydrocarbons but much higher proportions of CO{sub 2}. The carbonic fluid coexisted immiscibly with a brine, which on the basis of field and petrographic evidence, was interpreted to have originated from the magma. However, thermodynamic calculations indicate that the above gas species, specifically the hydrocarbons, could not have coexisted at equilibrium in the proportions measured, at any geologically reasonable conditions either prior to or post entrapment. We propose, instead, that the gas compositions measured in the Strange Lake inclusions, and in inclusions from other alkalic complexes, resulted from the production of H{sub 2} during the alteration of arfvedsonite to aegirine, and the subsequent reaction of this H{sub 2} with orthomagmatic CO{sub 2} and CO to form hydrocarbons in a magnetite-catalysed Fischer-Tropsch synthesis. Locally, influx of an oxidised calcic brine, derived externally from the pluton, altered the original composition of the fluid by converting hydrocarbons to CO{sub 2}. 70 refs., 7 figs., 5 tabs.

  7. Textural, mineralogical and stable isotope studies of hydrothermal alteration in the main sulfide zone of the Great Dyke, Zimbabwe and the precious metals zone of the Sonju Lake Intrusion, Minnesota, USA

    USGS Publications Warehouse

    Li, C.; Ripley, E.M.; Oberthur, T.; Miller, J.D., Jr.; Joslin, G.D.

    2008-01-01

    Stratigraphic offsets in the peak concentrations of platinum-group elements (PGE) and base-metal sulfides in the main sulfide zone of the Great Dyke and the precious metals zone of the Sonju Lake Intrusion have, in part, been attributed to the interaction between magmatic PGE-bearing base-metal sulfide assemblages and hydrothermal fluids. In this paper, we provide mineralogical and textural evidence that indicates alteration of base-metal sulfides and mobilization of metals and S during hydrothermal alteration in both mineralized intrusions. Stable isotopic data suggest that the fluids involved in the alteration were of magmatic origin in the Great Dyke but that a meteoric water component was involved in the alteration of the Sonju Lake Intrusion. The strong spatial association of platinum-group minerals, principally Pt and Pd sulfides, arsenides, and tellurides, with base-metal sulfide assemblages in the main sulfide zone of the Great Dyke is consistent with residual enrichment of Pt and Pd during hydrothermal alteration. However, such an interpretation is more tenuous for the precious metals zone of the Sonju Lake Intrusion where important Pt and Pd arsenides and antimonides occur as inclusions within individual plagioclase crystals and within alteration assemblages that are free of base-metal sulfides. Our observations suggest that Pt and Pd tellurides, antimonides, and arsenides may form during both magmatic crystallization and subsolidus hydrothermal alteration. Experimental studies of magmatic crystallization and hydrothermal transport/deposition in systems involving arsenides, tellurides, antimonides, and base metal sulfides are needed to better understand the relative importance of magmatic and hydrothermal processes in controlling the distribution of PGE in mineralized layered intrusions of this type. ?? Springer-Verlag 2007.

  8. Ambient Nitrogen Deposition Gradients in the Rocky Mountains and the Effect on Alpine Moist Meadow Ecosystems

    NASA Astrophysics Data System (ADS)

    Churchill, A. C.; Bowman, W. D.

    2012-12-01

    The chronic ambient deposition of nitrogen (N) in alpine ecosystems can have cascading effects on plants, soils and hydrology in both the alpine and areas downstream through leaching and ecosystem export. Nitrogen is traditionally a nutrient limiting for plant growth in the alpine zone and the addition of anthropogenically derived nitrogen has the potential to alter nutrient composition and interactions between soil, plants and hydrology. While deposition is globally widespread its spatial impacts are associated with a proximity to agriculture (fertilizers) and industry (hydrocarbon byproducts), creating gradients of deposition with distance from point sources. Consequently, N deposition levels and potential environmental impacts on ecosystem processes increase in regions with expanding populations and changes in land use. The Rocky Mountains face both enhanced deposition associated with high levels of precipitation at high elevations and increases in anthropogenic sources of nitrogen from conversion of prairie to agricultural fields or development of new roads and housing communities. Our study focuses on linking gradients of ambient nitrogen deposition to responses within the alpine ecosystem, in particular the interactions between plants and soils within moist meadow communities. Previous studies have focused on the effects of N deposition within alpine dry meadows, as these are abundant and generally higher in elevation than other alpine meadow community types. Within these systems critical loads have been estimated to determine at what level N addition directly alters the ecosystem. Alpine moist meadows, however, also cover a substantial portion of the alpine zone, and support a very different plant community with naturally lower species richness. These areas receive heavier snowfall, and are more dependent on the snowpack for ephemeral water availability making them potentially more susceptible to nutrient loading within the snowpack. Along our ambient N

  9. Chernobyl fallout on Alpine glaciers

    SciTech Connect

    Ambach, W.; Rehwald, W.; Blumthaler, M.; Eisner, H.; Brunner, P.

    1989-01-01

    Measurements of the gross beta activity of snow samples from four Alpine glaciers contaminated by radioactive fallout from the Chernobyl nuclear accident and a gamma-spectrum analysis of selected samples are reported. The results are discussed with respect to possible risks to the population from using meltwater from these glaciers as drinking water.

  10. Alpine Skiing in the Classroom

    ERIC Educational Resources Information Center

    Mendez-Gimenez, Antonio; Fernandez-Rio, Javier

    2012-01-01

    Many students settle indoors in the winter. However, this does not mean that winter should be a period of time with no physical activity. Several snow activities could be practiced during those months, such as ice-skating, ice-hockey, snowshoeing, cross-country skiing, alpine skiing, or snowboarding. In order to counteract the tendency for…

  11. Invasive Mussels Alter the Littoral Food Web of a Large Lake: Stable Isotopes Reveal Drastic Shifts in Sources and Flow of Energy

    PubMed Central

    Ozersky, Ted; Evans, David O.; Barton, David R.

    2012-01-01

    We investigated how establishment of invasive dreissenid mussels impacted the structure and energy sources of the littoral benthic food web of a large temperate lake. We combined information about pre- and postdreissenid abundance, biomass, and secondary production of the littoral benthos with results of carbon and nitrogen stable isotope analysis of archival (predreissenid) and recent (postdreissenid) samples of all common benthic taxa. This approach enabled us to determine the importance of benthic and sestonic carbon to the littoral food web before, and more than a decade after dreissenid establishment. Long term dreissenid presence was associated with a 32-fold increase in abundance, 6-fold increase in biomass, and 14-fold increase in secondary production of the littoral benthos. Dreissenids comprised a large portion of the post-invasion benthos, making up 13, 38, and 56% of total abundance, biomass, and secondary production, respectively. The predreissenid food web was supported primarily by benthic primary production, while sestonic material was relatively more important to the postdreissenid food web. The absolute importance of both sestonic material and benthic primary production to the littoral benthos increased considerably following dreissenid establishment. Our results show drastic alterations to food web structure and suggest that dreissenid mussels redirect energy and material from the water column to the littoral benthos both through biodeposition of sestonic material as well as stimulation of benthic primary production. PMID:23284673

  12. Timing and extent of early marine oxygen isotope stage 2 alpine glaciation in Skagit Valley, Washington

    NASA Astrophysics Data System (ADS)

    Riedel, Jon L.; Clague, John J.; Ward, Brent C.

    2010-03-01

    Twenty-two new radiocarbon ages from Skagit valley provide a detailed chronology of alpine glaciation during the Evans Creek stade of the Fraser Glaciation (early marine oxygen isotope stage (MIS) 2) in the Cascade Range, Washington State. Sediments at sites near Concrete, Washington, record two advances of the Baker valley glacier between ca. 30.3 and 19.5 cal ka BP, with an intervening period of glacier recession about 24.9 cal ka BP. The Baker valley glacier dammed lower Skagit valley, creating glacial Lake Concrete, which discharged around the ice dam along Finney Creek, or south into the Sauk valley. Sediments along the shores of Ross Lake in upper Skagit valley accumulated in glacial Lake Skymo after ca. 28.7 cal ka BP behind a glacier flowing out of Big Beaver valley. Horizontally laminated silt and bedded sand and gravel up to 20 m thick record as much as 8000 yr of deposition in these glacially dammed lakes. The data indicate that alpine glaciers in Skagit valley were far less extensive than previously thought. Alpine glaciers remained in advanced positions for much of the Evans Creek stade, which may have ended as early as 20.8 cal ka BP.

  13. Lake whitefish and lake herring population structure and niche in ten south-central Ontario lakes

    USGS Publications Warehouse

    Carl, Leon M.; McGuiness, Fiona

    2006-01-01

    This study compares simple fish communities of ten oligotrophic lakes in south-central Ontario. Species densities and population size structure vary significantly among these lake communities depending on fish species present beyond the littoral zone. Lake whitefish are fewer and larger in the presence of lake herring than in their absence. Diet analysis indicates that lake whitefish shift from feeding on both plankton and benthic prey when lake herring are absent to a primarily benthic feeding niche in the presence of lake herring. When benthic round whitefish are present, lake whitefish size and density decline and they move lower in the lake compared to round whitefish. Burbot are also fewer and larger in lakes with lake herring than in lakes without herring. Burbot, in turn, appear to influence the population structure of benthic coregonine species. Lower densities of benthic lake whitefish and round whitefish are found in lakes containing large benthic burbot than in lakes with either small burbot or where burbot are absent. Predation on the pelagic larvae of burbot and lake whitefish by planktivorous lake herring alters the size and age structure of these populations. As life history theory predicts, those species with poor larval survival appear to adopt a bet-hedging life history strategy of long-lived individuals as a reproductive reserve.

  14. Nd, Sr, Pb, Ar, and O isotopic systematics of Sturgeon Lake kimberlite, Saskatchewan, Canada: constraints on emplacement age, alteration, and source composition

    NASA Astrophysics Data System (ADS)

    Hegner, E.; Roddick, J. C.; Fortier, S. M.; Hulbert, L.

    1995-06-01

    Rb-Sr isotopic dating of phlogopite megacryst samples separated from Sturgeon Lake kimberlite, Saskatchewan, yields a crystallization age of 98±1 Ma (2 σ, MSWD=1.2; 87Sr/86Sr( t)=0.7059). The 40Ar/39Ar analyses of a phlogopite megacryst sample indicate the presence of large amounts of excess 40Ar and yield an excessively old age of ˜410 Ma. Assessment of the Ar data using isotope correlation plots indicates clustering of the data points about a mixing line between the radiogenic 40Ar component at 98 Ma and a trapped component with uniform 36Ar/40Ar and Cl/40Ar. Values of δ 18O as high as +20‰ (VSMOW) for calcite from the groundmass and a whole-rock sample indicate pervasive low-temperature alteration. The δ 13C of matrix carbonate is -11.3‰ (PDB), slightly lighter than typical values from the literature. The δ 18O values of about +5‰ (VSMOW) for brown phlogopite megacrysts may be primary, green phlogopites are interpreted to be an alteration product of the brown variety and are 2‰ heavier. Initial Nd-Sr-Pb isotopic ratios for a whole-rock sample ( ɛ Nd=+0.8; 87Sr/86Sr=0.7063, 206Pb/204Pb=18.67, 207Pb/204Pb=15.54, 208Pb/204Pb=38.97) suggest an affinity with group I kimberlites. Initial ɛ Nd values of +1.7 and +0.5 (87Sr/86Sr( t)=0.7053 and 0.7050) for eclogitic and lherzolitic garnet megacryst samples, and values of 0.0 for two phlogopite megacryst samples reflect an origin from an isotopically evolving melt due to assimilation of heterogeneous mantle. Lilac high-Cr lherzolitic garnet megacrysts give an unusually high ɛ Nd(98. Ma) of +28.6 (87Sr/86Sr=0.7046) indicating a xenocrystic origin probably from the lithospheric mantle. The very radiogenic 87Sr/86Sr and 206Pb/204Pb ratios of the kimberlite are consistent with melting of EM II (enriched) mantle components.

  15. Alterations in the distribution and bioaccumulation of trace elements in six acidic and non-acidic clearwater lakes in New Jersey

    SciTech Connect

    Sprenger, M.D.

    1986-01-01

    Six study lakes were selected in an area geologically sensitive to acid deposition atop the Kittatinny Ridge in northwestern New Jersey. The study lakes were sampled seasonally for the determination of general water quality parameters and trace element concentrations in the water and aquatic flora. Sediment cores were collected from these lakes for the determination of the depositional patterns of aluminum (Al), cadmium (Cd), copper (Cu), iron (Fe), manganese (Mn), lead (Pb) and zinc (Zn) for use in assessment of historical elemental loadings and the acidification process in these lakes. It was found that significant differences in pH and trace element distribution in water, biota and sediment existed between the study lakes. A transplant experiment performed in three of the study lakes using a rooted and a non-rooted macrophyte, demonstrated that while uptake of Pb in the most acidic lakes increased, accumulation of Zn decreased. It is postulated that the competitive effects of hydrogen ions were responsible for the observed decrease in Zn availability in the most acidic lakes.

  16. Abiotic and biotic controls of spatial pattern at alpine treeline

    USGS Publications Warehouse

    Malanson, George P.; Xiao, Ningchuan; Alftine, K.J.; Bekker, Mathew; Butler, David R.; Brown, Daniel G.; Cairns, David M.; Fagre, Daniel; Walsh, Stephen J.

    2000-01-01

    At alpine treeline, trees and krummholz forms affect the environment in ways that increase their growth and reproduction. We assess the way in which these positive feedbacks combine in spatial patterns to alter the environment in the neighborhood of existing plants. The research is significant because areas of alpine tundra are susceptible to encroachment by woody species as climate changes. Moreover, understanding the general processes of plant invasion is important. The importance of spatial pattern has been recognized, but the spatial pattern of positive feedbacks per se has not been explored in depth. We present a linked set of models of vegetation change at an alpine forest-tundra ecotone. Our aim is to create models that are as simple as possible in order to test specific hypotheses. We present results from a model of the resource averaging hypothesis and the positive feedback switch hypothesis of treelines. We compare the patterns generated by the models to patterns observed in fine scale remotely sensed data.

  17. Hydrological Trends in a High Alpine Watershed in Rocky Mountain National Park

    NASA Astrophysics Data System (ADS)

    Pina, A.; Moore, C. E.; Records, R.; Medina, I. D.; Miner, G. L.

    2014-12-01

    Recent studies reveal amplified air temperature warming trends in the Rocky Mountains than global averages, as well as earlier snowmelt timing and decreased snow-water equivalent (SWE) relative to past records in this region. Changes in SWE and snowmelt runoff timing directly impact water availability in alpine watersheds as well as downstream ecosystem services. In this study we evaluated local trends in air temperature, precipitation, snowpack, and streamflow timing to look for similarities to regional trends reported in literature. We assessed two long-term alpine data collection sites in Rocky Mountain National Park: Bear Lake SNOTEL site (2896 m; 1981-2013) and Loch Vale Watershed (3159 m; 1984-2011), using the Mann-Kendall test to examine trends in average monthly temperature, number of days above freezing, peak SWE depth and timing, number of snow-free days, and total precipitation at Bear Lake, as well as streamflow volume and timing metrics at the outlet of Loch Vale. We found seasonal patterns and magnitudes of warming similar to regional trend findings, with significant increasing trends in average monthly mean air temperatures for most months. The average number of days below 0ºC also significantly decreased in fall and winter. However, we found no significant trends in peak SWE, discharge rate, precipitation, accumulated snowfall, or the number of snow-free days at Bear Lake or Loch Vale sites. These results suggest reported regional warming trends are not reflected in localized snowmelt trends in alpine Rocky Mountain watersheds.

  18. Magnetic Signature of Glacial Flour in Sediments From Bear Lake, Utah/Idaho

    NASA Astrophysics Data System (ADS)

    Rosenbaum, J. G.; Dean, W. E.; Colman, S. M.; Reynolds, R. L.

    2002-12-01

    Variations in magnetic properties within an interval of Bear Lake sediments correlative with oxygen isotope stage 2 (OIS 2) and OIS 3 provide a record of glacial flour production for the Uinta Mountains. Like sediments of the same age from Upper Klamath Lake (OR), these Bear Lake sediments have high magnetic susceptibilities (MS) relative to non-glacial-age sediments and contain well-defined millennial-scale variations in magnetic properties. In contrast to glacial flour derived from volcanic rocks surrounding Upper Klamath Lake, glacial flour derived from the Uinta Mountains and deposited in Bear Lake by the Bear River has low magnetite content but high hematite content. The relatively low MS values of younger and older non-glacial-age sediments are due entirely to dilution by non-magnetic endogenic carbonate and to the effects of sulfidic alteration of detrital Fe-oxides. Analysis of samples from streams entering Bear Lake and from along the course of the Bear River demonstrates that, in comparison to other areas of the catchment, sediment derived from the Uinta Mountains is rich in hematite (high HIRM) and aluminum, and poor in magnetite (low MS) and titanium. Within the glacial-age lake sediments, there are strong positive correlations among HIRM, Al/Ti, and fine sediment grain size. MS varies inversely with theses three variables. These relations indicate that the observed millennial-scale variations in magnetic and chemical properties arise from varying proportions of two detrital components: (1) very fine-grained glacial flour derived from Proterozoic metasedimentary rocks in the Uinta Mountains and characterized by high HIRM and low MS, and (2) somewhat coarser material, characterized by higher MS and lower HIRM, derived from widespread sedimentary rocks along the course of the Bear River and around Bear Lake. Measurement of glacial flour incorporated in lake sediments can provide a continuous history of alpine glaciation, because the rate of accumulation

  19. Europe's battery: The making of the Alpine energy landscape, 1870-1955

    NASA Astrophysics Data System (ADS)

    Landry, Marc D., II

    This study examines the environmental history of hydropower development in the Alps from the mid-nineteenth to the mid-twentieth centuries. Analyzing government archival files, associational journals, conference proceedings, and published contemporary material from several Alpine countries, it seeks to determine how and why Europeans modified the Alpine landscape to generate hydropower, and to explore the consequences of these decisions. I argue that during this time period, Europeans thoroughly transformed the Alpine environment, creating what I call "Europe's Battery": a gigantic system for storing hydropower and distributing it on a continental scale. This study shows how nineteenth-century innovations in energy technology contributed to a dramatic shift in the perception of the Alps as a landscape of "white coal." It demonstrates how at the outset of electrification, Europeans modified Alpine waterways on an unprecedented scale in order to tap into the power of flowing Alpine water. I show how after the turn of the twentieth century, Europeans took advantage of the unique mountain environment to store water, first by converting existing lakes into reservoirs. The practice countered what was perceived to be the greatest disadvantage of white coal: its climate-influenced inconstancy. This study shows the importance of war, and especially the First World War, in the forging of the new Alpine landscape. Finally, this study illustrates how from the interwar period to the aftermath of the Second World War, Europeans put the finishing touches on the new Alpine energy landscape by creating large reservoirs behind dams and feeding Alpine hydroelectricity into a burgeoning European electricity grid. By 1955 the Alps had become one of the most important energy landscapes in Europe. This history of the Alpine energy landscape contributes to a number of historiographical fields. It represents an important chapter in the environmental history of one of the world's most

  20. Alpine 1/Federal: Executive summary final report

    SciTech Connect

    Witcher, J.C.

    1994-04-01

    This summary report overviews a State of Arizona and US Department of Energy funded drilling project to determine if near-term hot dry rock (HDR) geothermal potential exists in the eastern portion of the White Mountains region of Arizona. A 4,505 feet deep slim-hole exploratory well, Alpine1/Federal, was drilled within the Apache-Sitgreaves National Forest at Alpine Divide near the Alpine Divide camp ground about 5 miles north of Alpine, Arizona in Apache County (Figure 1). A comprehensive technical report, in two parts, details the results of the project. Part 1, Alpin1/Federal, Drilling Report discusses the drilling operations, logging program, permitting and site selection for the hole. Part 2, Temperature Gradients, Geothermal Potential, and Geology, summarizes the temperature gradients, heat flow, geothermal potential, and subsurface geology.

  1. Fluids preserved in variably altered graphitic pelitic schists in the Dufferin Lake Zone, south-central Athabasca Basin, Canada: implications for graphite loss and uranium deposition

    NASA Astrophysics Data System (ADS)

    Pascal, Marjolaine; Boiron, Marie-Christine; Ansdell, Kevin; Annesley, Irvine R.; Kotzer, Tom; Jiricka, Dan; Cuney, Michel

    2016-06-01

    The Athabasca Basin (Canada) contains the highest grade unconformity-type uranium deposits in the world. Underlying the Athabasca Group sedimentary rocks of the Dufferin Lake Zone are variably graphitic, pelitic schists (VGPS), altered to chlorite and hematite (Red/Green Zone: RGZ). They were locally bleached near the unconformity during paleoweathering and/or later fluid interaction. Overall, graphite was lost from the RGZ and the bleached zone relative to the original VGPS. Fluid inclusions were examined in different generations of quartz veins, using microthermometry and Raman spectroscopy, to characterize and compare the different fluids that interacted with the RGZ and the VGPS. In the VGPS, CH4-, and N2-rich fluid inclusions, which homogenize into the vapor phase between -100 and -74 °C, and -152 and -125 °C, respectively, and CO2-rich fluid inclusions, homogenizing either into vapor or liquid between 20 and 28 °C, are present. Carbonic fluids could be the result of the breakdown of graphite to CH4 + CO2, whereas N2-rich fluid is interpreted to be the result of breakdown of feldspars/micas to NH4 ++N2. In the RGZ, the presence of fluid inclusions with low ice melting temperature (-38 to -16 °C) reflect the presence of CaCl2, and fluid inclusions with halite daughter minerals that dissolve between 190 and 240 °C indicate the presence of highly saline fluids. These fluids are interpreted to be derived from the Athabasca Basin. The circulation of carbonic fluids and brines occurred during two different events related to different P-T conditions of trapping. The carbonic fluids interacted with basement rocks during retrograde metamorphism of the basement rocks before deposition of the Athabasca Basin, whereas the brines circulated after the deposition of the Athabasca Basin. These latter fluids are similar to brines related to uranium mineralization at McArthur River and thus, in addition to possibly being related to graphite depletion in the RGZ, they could

  2. Fluids preserved in variably altered graphitic pelitic schists in the Dufferin Lake Zone, south-central Athabasca Basin, Canada: implications for graphite loss and uranium deposition

    NASA Astrophysics Data System (ADS)

    Pascal, Marjolaine; Boiron, Marie-Christine; Ansdell, Kevin; Annesley, Irvine R.; Kotzer, Tom; Jiricka, Dan; Cuney, Michel

    2015-12-01

    The Athabasca Basin (Canada) contains the highest grade unconformity-type uranium deposits in the world. Underlying the Athabasca Group sedimentary rocks of the Dufferin Lake Zone are variably graphitic, pelitic schists (VGPS), altered to chlorite and hematite (Red/Green Zone: RGZ). They were locally bleached near the unconformity during paleoweathering and/or later fluid interaction. Overall, graphite was lost from the RGZ and the bleached zone relative to the original VGPS. Fluid inclusions were examined in different generations of quartz veins, using microthermometry and Raman spectroscopy, to characterize and compare the different fluids that interacted with the RGZ and the VGPS. In the VGPS, CH4-, and N2-rich fluid inclusions, which homogenize into the vapor phase between -100 and -74 °C, and -152 and -125 °C, respectively, and CO2-rich fluid inclusions, homogenizing either into vapor or liquid between 20 and 28 °C, are present. Carbonic fluids could be the result of the breakdown of graphite to CH4 + CO2, whereas N2-rich fluid is interpreted to be the result of breakdown of feldspars/micas to NH4 ++N2. In the RGZ, the presence of fluid inclusions with low ice melting temperature (-38 to -16 °C) reflect the presence of CaCl2, and fluid inclusions with halite daughter minerals that dissolve between 190 and 240 °C indicate the presence of highly saline fluids. These fluids are interpreted to be derived from the Athabasca Basin. The circulation of carbonic fluids and brines occurred during two different events related to different P-T conditions of trapping. The carbonic fluids interacted with basement rocks during retrograde metamorphism of the basement rocks before deposition of the Athabasca Basin, whereas the brines circulated after the deposition of the Athabasca Basin. These latter fluids are similar to brines related to uranium mineralization at McArthur River and thus, in addition to possibly being related to graphite depletion in the RGZ, they could

  3. Lake Life.

    ERIC Educational Resources Information Center

    Ohrn, Deborah Gore, Ed.

    1993-01-01

    This quarterly publication of the State Historical Society of Iowa features articles and activities for elementary school students. This summer issue focuses on the topic of lake life. The issue includes the following features: (1) "Where the Lakes Are Map"; (2) "Letter from the Lake"; (3) "Lake People"; (4) "Spirit Lake"; (5) "Lake Manawa"; (6)…

  4. Moisture and temperature controls on nitrification differ among ammonia oxidizer communities from three alpine soil habitats

    NASA Astrophysics Data System (ADS)

    Osborne, Brooke B.; Baron, Jill S.; Wallenstein, Matthew D.

    2016-03-01

    Climate change is altering the timing and magnitude of biogeochemical fluxes in many highelevation ecosystems. The consequent changes in alpine nitrification rates have the potential to influence ecosystem scale responses. In order to better understand how changing temperature and moisture conditions may influence ammonia oxidizers and nitrification activity, we conducted laboratory incubations on soils collected in a Colorado watershed from three alpine habitats (glacial outwash, talus, and meadow). We found that bacteria, not archaea, dominated all ammonia oxidizer communities. Nitrification increased with moisture in all soils and under all temperature treatments. However, temperature was not correlated with nitrification rates in all soils. Site-specific temperature trends suggest the development of generalist ammonia oxidzer communities in soils with greater in situ temperature fluctuations and specialists in soils with more steady temperature regimes. Rapidly increasing temperatures and changing soil moisture conditions could explain recent observations of increased nitrate production in some alpine soils.

  5. Moisture and temperature controls on nitrification differ among ammonia oxidizer communities from three alpine soil habitats

    USGS Publications Warehouse

    Osborne, Brooke B; Baron, Jill S.; Wallenstein, Matthew D.

    2015-01-01

    Climate change is altering the timing and magnitude of biogeochemical fluxes in many high elevation ecosystems. The consequent changes in alpine nitrification rates have the potential to influence ecosystem scale responses. In order to better understand how changing temperature and moisture conditions may influence ammonia oxidizers and nitrification activity, we conducted laboratory incubations on soils collected in a Colorado watershed from three alpine habitats (glacial outwash, talus, and meadow). We found that bacteria, not archaea, dominated all ammonia oxidizer communities. Nitrification increased with moisture in all soils and under all temperature treatments. However, temperature was not correlated with nitrification rates in all soils. Site-specific temperature trends suggest the development of generalist ammonia oxidizer communities in soils with greater in situ temperature fluctuations and specialists in soils with more steady temperature regimes. Rapidly increasing temperatures and changing soil moisture conditions could explain recent observations of increased nitrate production in some alpine soils.

  6. Seed dormancy in alpine species

    PubMed Central

    Schwienbacher, Erich; Navarro-Cano, Jose Antonio; Neuner, Gilbert; Erschbamer, Brigitta

    2011-01-01

    In alpine species the classification of the various mechanisms underlying seed dormancy has been rather questionable and controversial. Thus, we investigated 28 alpine species to evaluate the prevailing types of dormancy. Embryo type and water impermeability of seed coats gave an indication of the potential seed dormancy class. To ascertain the actual dormancy class and level, we performed germination experiments comparing the behavior of seeds without storage, after cold-dry storage, after cold-wet storage, and scarification. We also tested the light requirement for germination in some species. Germination behavior was characterized using the final germination percentage and the mean germination time. Considering the effects of the pretreatments, a refined classification of the prevailing dormancy types was constructed based on the results of our pretreatments. Only two out of the 28 species that we evaluated had predominantly non-dormant seeds. Physiological dormancy was prevalent in 20 species, with deep physiological dormancy being the most abundant, followed by non-deep and intermediate physiological dormancy. Seeds of four species with underdeveloped embryos were assigned to the morphophysiologial dormancy class. An impermeable seed coat was identified in two species, with no additional physiological germination block. We defined these species as having physical dormancy. Light promoted the germination of seeds without storage in all but one species with physiological dormancy. In species with physical dormancy, light responses were of minor importance. We discuss our new classification in the context of former germination studies and draw implications for the timing of germination in the field. PMID:24415831

  7. Climate induced changes in high-elevation lake chemistry and the importance of sulfide weathering

    NASA Astrophysics Data System (ADS)

    Mast, A.; Holland-Sears, A.

    2009-12-01

    Despite downward trends in precipitation sulfate concentrations across Colorado, high-elevation lakes in several wilderness areas in the region show sharp increases in lake-water sulfate concentrations during 1985-2008. Similar increases in sulfate concentrations have been reported for numerous alpine lakes in Europe, which have been attributed to enhanced weathering rates, increased biological activity, and/or melting of permanent ice features caused by increasing air temperatures. Analysis of climate records from Colorado SNOTEL stations shows increases in annual air temperature of 0.43 to 0.93 °C per decade over most mountainous areas suggesting climate also may be a factor for the Colorado lakes. Sulfur isotopic data for a subset of lakes reveals that sulfate is largely derived from the weathering of pyrite, which is associated with hydrothermally altered and mineralized bedrock. Unlike the weathering of silicate minerals, pyrite breakdown is largely dependent on oxygen availability and can be accelerated by fluctuating groundwater levels, which enhance exposure of mineralized rock to oxygen as water levels decline. We suggest that during warmer, drier years the water table declines enhancing pyrite oxidation and build up of soluble salts in the unsaturated zone. During the subsequent snowmelt, these salts are flushed from soils and sediments resulting in increased solute concentrations in lakes. If climate change in mountainous areas results in increased summer warming or a greater frequency of drought years, then the magnitude of sulfate export from mineralized watersheds may continue to increase. Because pyrite is often associated with other base-metal sulfides and its breakdown generates acidity, climate changes could result in increased acidity and trace metal concentrations in surface water to levels where impacts on aquatic life may become evident. Futhermore, climate change may act to decrease critical loads in these mineralized watersheds unlike the

  8. Hybridization and restricted gene flow between native and introduced stocks of Alpine whitefish (Coregonus sp.) across multiple environments

    PubMed Central

    Winkler, Kathrin A; Pamminger-Lahnsteiner, Barbara; Wanzenböck, Josef; Weiss, Steven

    2011-01-01

    Translocations of Baltic whitefish (Coregonus sp.) into Austrian Alpine lakes have created ‘artificial hybrid zones’, threatening the genetic integrity of native lineages. We evaluate the genetic structure of Coregonus in Austrian lakes and characterize hybridization and introgression between native and introduced lineages. Fifteen populations (N= 747) were assessed for allelic variation at eight microsatellite loci and a reduced set (N= 253) for variation across two mtDNA genes (cyt b and NADH-3). Bayesian approaches were used to estimate individual admixture proportions (q-values) and classify genotypes as native, introduced or hybrids. q-value distributions varied among populations highlighting differential hybridization and introgression histories. Many lakes revealed a clear distinction between native and introduced genotypes despite hybridization, whereas some locations revealed hybrid swarms. Genetic structure among lakes was congruent with morphological divergence and novelty raising speculation of multiple taxa, including a population south of the Alps, outside the putative native range of Coregonus. Although statistically congruent with inferences based on nuclear markers, mitochondrial haplotype data was not diagnostic with respect to native and non-native lineages, supporting that the Alpine region was colonized post-glacially by an admixture of mtDNA lineages, which coalesce >1 Ma. Mechanisms promoting or eroding lineage isolation are discussed, as well as a high potential to conserve native Alpine lineages despite the extensive historical use of introduced Baltic stocks. PMID:21199024

  9. GENE EXPRESSION ALTERATIONS OBSERVED IN PRIMARY CULTURED RAT HEPATOCYTES AFTER TREATMENT WITH CHLORINATED OR CHLORINATED AND OZONATED DRINKING WATER FROM EAST FORK LAKE, OHIO

    EPA Science Inventory

    Drinking water from East Fork Lake was spiked with iodide and bromide, disinfected with chlorine or ozone + chlorine, concentrated ~100-fold using reverse osmosis, and volatile disinfection by-products (DBPs) added back. Primary rat hepatocytes were exposed to full-strength, 1:10...

  10. Polycyclic aromatic hydrocarbons in lake sediments from the High Tatras.

    PubMed

    van Drooge, Barend L; López, Jordi; Fernández, Pilar; Grimalt, Joan O; Stuchlík, Evzen

    2011-05-01

    European alpine lake systems are used as indicators of air quality over the continent. Preliminary data showed high polycyclic aromatic hydrocarbons (PAH) loads in the High Tatras (Eastern Europe) in comparison to other mountain regions. Here, insight on the spatial distribution of PAH is provided from analysis of top-core sediments of 27 alpine lakes distributed along the High Tatras. Top-core sediment concentrations were higher than those in deep-cores, and they were higher than those observed in other European high mountain regions. The PAH profiles were uniform and comparable to those observed in aerosols and snow, indicating that atmospheric deposition was the predominant PAH input pathway to the lakes. Good agreement between estimated atmospheric deposition and sedimentation fluxes was observed. However, in several lakes in the western range higher sediment fluxes may correspond to higher PAH depositions levels. The higher concentrations may also reflect inputs from potential emission source areas. PMID:21353356

  11. Erosion by an Alpine glacier.

    PubMed

    Herman, Frédéric; Beyssac, Olivier; Brughelli, Mattia; Lane, Stuart N; Leprince, Sébastien; Adatte, Thierry; Lin, Jiao Y Y; Avouac, Jean-Philippe; Cox, Simon C

    2015-10-01

    Assessing the impact of glaciation on Earth's surface requires understanding glacial erosion processes. Developing erosion theories is challenging because of the complex nature of the erosion processes and the difficulty of examining the ice/bedrock interface of contemporary glaciers. We demonstrate that the glacial erosion rate is proportional to the ice-sliding velocity squared, by quantifying spatial variations in ice-sliding velocity and the erosion rate of a fast-flowing Alpine glacier. The nonlinear behavior implies a high erosion sensitivity to small variations in topographic slope and precipitation. A nonlinear rate law suggests that abrasion may dominate over other erosion processes in fast-flowing glaciers. It may also explain the wide range of observed glacial erosion rates and, in part, the impact of glaciation on mountainous landscapes during the past few million years. PMID:26450208

  12. Quaternary geology of the DFDP-2 drill holes, Alpine Fault, New Zealand

    NASA Astrophysics Data System (ADS)

    Upton, P.; Cox, S.; Howarth, J. D.; Sutherland, R.; Langridge, R.; Barth, N. C.; Atkins, C.

    2015-12-01

    A 240 m-thick Quaternary sediment sequence in Whataroa Valley was much thicker than predicted before drilling. DFDP-2A and DFDP-2B were mostly drilled through the sequence by dual-rotary method using air or water circulation, returning cuttings bagged at 1 or 2 m sample intervals. Some sorting/bias and contamination occurred. Core was retrieved in DFDP-2A from 125-160 m, with highly variable recovery (0-100%) and mixed preservation/quality. The sequence is interpreted to comprise: fluvial-glacial gravels (0-58 m); grading downward into sandy lake delta sediments (59-77 m); overlying a monotonous sequence of lake mud and silts, with rare pebble-cobble diamictite (77-206 m); with a basal unit (206-240 m) containing coarse cobbles and boulders that may represent a distinct till/diamictite. Evidence has yet to be found for any marine influence in lowermost sediments, despite deposition at least 120 m below present day sea level, and potentially 200 m bsl if uplift has occurred on the Alpine Fault. When corrected for uplift the lacustrine sequence broadly correlates to those in present Lakes Rotokina and Wahapo, suggesting a substantial (~100 km2) pro-glacial lake once covered the area. Radiocarbon dating of plant fragments indicate 70 m of upper lacustrine and deltaic sediments (129-59 m) were deposited rapidly between 16350-15800 Cal BP. Overlying alluvial gravels are much younger (<1 ka), but potentially also involved pulses of rapid aggradation. The sequence provides a record of sedimentation on the Alpine Fault hanging wall following late-glacial ice retreat up Whataroa Valley, with uplift and erosion followed by Holocene alluvial gravel deposition. Future work will address: (1) the nature and history of sedimentation, including the lithology and origin of sediments; (2) what, if any, geological record of tectonics (movement) or Alpine Fault earthquakes (shaking) the sediments contain.

  13. The "stream power" of the Alpine Rivers

    NASA Astrophysics Data System (ADS)

    Salcher, Bernhard; Champagnac, Jean-Daniel

    2010-05-01

    We examine the spatial pattern of fluvial erosion on the entire European Alps and adjacent areas by applying the widely used stream power model (e.g. Whipple and Tucker, 1999). According to that model, the bedrock incision rate (E) equals the water flux (upstream contributing area (A) times rainfall (W)) multiplied by the channel slope (S) and a coefficient K which aggregates the influence of many factors, e.g. rock resistance to erosion or channel geometry. E= (Am * W) * Sn * K We apply the stream power (SP) approach as a generalized abstraction of erosional processes in the Alps using the highest available DEM (ASTER GDEM) for the entire orogen in a resolution of 1" (~30m). Climatic variability is implemented in to the SP adding a precipitation correction factor (average precipitation per year). We further average rates of large drainage basins' stream power to compare with existing post-LGM and Holocene erosion rates (Hinderer, 2001; Wittmann et al., 2007; Champagnac et al., 2009). Results show that the ice extension during the LGM is still represented in the extracted stream power. More specifically, SP values generally start to rise as soon as streams reach the areas of the former piedmont ice lobes. Outside of the LGM limits, SP values rise continuously, representing generally higher values in bedrock sections and lower values in alluvial-dominated sections. To better interpret the relative potential for erosion across the entire Alps, we use an averaged moving window on large catchments, and across the belt as a whole. At the scale of our analysis SP is used as a surrogate for the spatial pattern of erosion for which values may be used as an index of erosion (e.g. Finlaysson and Montgomery). Finally, we examine the important role of different East and West Alpine base levels on SP and discuss the associated effects on the evolution of the belt: the large eastern alpine rivers show generally higher SP values than those in the western Alps (e.g. Rhine or Rh

  14. Mercury Sources and Cycling in the Great Lakes: Dramatic Changes Resulting from Altered Atmospheric Loads and the Near-Shore Shunt

    NASA Astrophysics Data System (ADS)

    Krabbenhoft, D. P.; DeWild, J. F.; Maglio, M. M.; Tate, M. T.; Ogorek, J. M.; Hurley, J. P.; Lepak, R.

    2013-12-01

    Mercury (Hg) contamination of the aquatic food webs across the Great Lakes remains a significant environmental issue. However, our ability to prescribe corrective actions has been significantly hampered by a scarcity of data, particularly for methylmercury (MeHg) the most toxic and bioaccumulative form of mercury in freshwater ecosystems. As part of the Great Lakes Restoration Initiative initiated in 2010, a joint effort was undertaken by the U.S. Geological Survey (USGS) and U.S. Environmental Protection Agency (USEPA) to improve our understanding of total Hg and MeHg concentrations and distributions in the Great Lakes. Since 2010, sampling surveys have been conducted at about 15-20 stations twice annually (April and August) at 15-20 stations per lake to collect data from both cold and warm water conditions. All sampling was conducted using trace-metal free protocols using a sampling rosette equipped with 12 Teflon-lined Niskin. Water samples were collected at predetermined depths: mid-epilimnion, mid-thermocline, deep chlorophyll layer, mid-hypolimnion, and about 2 meters above the bottom. Seston samples were collected from the top 20 meters using plankton nets, while bottom sediments and benthos samples were acquired using a ponar sampler. Water, biota, and sediment samples were all analyzed for Hg and MeHg concentration at the USGS Mercury Research Laboratory in Middleton, Wisconsin. Several important trends are apparent from the water column samples. First, most stations reveal a strong top-to-bottom declining trend total Hg concentration, underscoring the importance of atmospheric deposition to the Great Lakes. Methylmercury profiles, show maximal concentrations at the thermocline or deep chlorophyll layer, suggesting in situ water-column MeHg production. Calculations suggest this in-lake MeHg source is similar in magnitude to tributary loading of MeHg, which heretofore was thought to be the dominant MeHg source. Aqueous total Hg results also suggest that

  15. Lake Biel Holocene sediment record before and after the Aare river deviation (1878 AD)

    NASA Astrophysics Data System (ADS)

    Jeannet, Alice; Corella, Juan Pablo; Kremer, Katrina; Girardclos, Stéphanie

    2014-05-01

    new river input is also linked to a massive and sudden Ti increase, and inversely abrupt Ca decrease in XRF data. This record reveals the significant alteration in the sediment dynamics, and the lake oxygenation changes that the lake experienced when it shifted from a relatively closed basin to a river and delta-influenced basin. Thank you to Flavio S. Anselmetti, Christine Guido and Frédéric Arlaud for help coring on the field and Stefanie Wirth for help at Limnogeology Laboratory. This study, undertaken as a Master thesis, was financed by the Swiss National Foundation projects 121666 and 146889. Reference Thevenon F. et al. 2013. Human impact on the transport of terrigenous and anthropogenic elements to peri-alpine lakes (Switzerland) over the last decades. Aquatic Sciences 75: 413-424.

  16. Rapid response of alpine timberline vegetation to the Younger Dryas climate oscillation in the Colorado Rocky Mountains, USA

    SciTech Connect

    Reasoner, M.A.; Jodry, M.A.

    2000-01-01

    Paleobotanical records from two high-altitude (>3,300 m) sites in Colorado show a clear and immediate response to the Younger Dryas climate oscillation. The Black Mountain Lake and Sky Pond records indicate that alpine timberline migrated upslope to near-modern elevations during the late Bolling-Allerod (13.6--12.9 ka). Subsequent declines in arboreal pollen percentages and accumulation rates during the Younger Dryas interval (12.9--11.7 ka) reflect a downslope displacement of the alpine timberline ecotone of 60--120 m in elevation. This change translates to a cooling of summer temperature by {approximately}0.4--0.9 C and is consistent with proposed Younger Dryas advances of alpine glaciers in the Rocky Mountains to positions close to Little Ice Age maxima. Alpine timberline readvanced upslope to elevations above both sites between 11.7 and 11.4 ka. The concomitant response of temperature-sensitive alpine timberline vegetation in Colorado and late-glacial changes in North Atlantic thermohaline circulating implicates a rapid, widespread atmospheric transmission of the Younger Dryas climate oscillation.

  17. Spatial and temporal patterns in water chemistry of two high elevation lakes in southeast Wyoming

    SciTech Connect

    Musselman, R.C.

    1995-12-31

    The Glacier Lakes Ecosystem Experiments Site (GLEES) was established to examine the effects of atmospheric deposition and climate change on alpine and subalpine ecosystems. This report documents temporal and spatial trends during 1993 in water chemistry in East and West Glacier Lakes. Data are presented on seasonal and lake depth changes in water chemistry of the two lakes. The application of the results to appropriate sampling protocols for two alpine lakes is discussed. Both lakes were sampled during the same day, at midday. Samples were kept cool, returned to the lab the same day, and filtered for analysis. Samples were analyzed for cations and anions, pH, and conductivity at the Rocky Mountain Station Water Chemistry laboratory. Silica and aluminum were also measured for some sample dates.

  18. High alpine ponds shift upwards as average temperatures increase: A case study of the Ortles-Cevedale mountain group (Southern Alps, Italy) over the last 50 years

    NASA Astrophysics Data System (ADS)

    Salerno, Franco; Gambelli, Sara; Viviano, Gaetano; Thakuri, Sudeep; Guyennon, Nicolas; D'Agata, Carlo; Diolaiuti, Guglielmina; Smiraglia, Claudio; Stefani, Fabrizio; Bocchiola, Daniele; Tartari, Gianni

    2014-09-01

    Alpine ecosystems are especially vulnerable to climate change, and lakes and ponds act as early indicators. Here, we describe our findings for the Ortles-Cevedale mountain group (Stelvio National Park, Southern Alps, Italy), where we used remote sensing to analyze more than 100 water ponds over the last 50 years (1954-2007). We found that since the 1980s, some lower elevation ponds (< 2500 m a.s.l.) have disappeared or experienced surface area reduction. We link this impact to the increased evaporation/precipitation ratio associated with climatic warming. At higher elevations (> 2900 m a.s.l.), we observed that since the 1950s, ponds have increased in size and that new ponds have appeared as a consequence of glacial shrinkage and retreat. However, these new ponds are ephemeral. The appearance of new environments is usually followed by their rapid disappearance and by a concomitant appearance of new ones, which is a clear sign of a transition from a glacial system to a paraglacial system. Surface area changes have been shown to be a highly visible and easily measurable signal of the impact of climate change on the alpine environment, as already demonstrated in other remote areas of the world. There is a clear need to extend this analysis to other sites in the Alps to gain a regional understanding of the phenomenon. The findings of this study make it possible to interpret the variations created by climate change in these environments, in terms of alteration of their ecological role and the loss of ecosystem services.

  19. Alpine radar conversion for LAWR

    NASA Astrophysics Data System (ADS)

    Savina, M.; Burlando, P.

    2012-04-01

    The Local Area Weather Radar (LAWR) is a ship-born weather radar system operating in X-band developed by the DHI Group to detect precipitation in urban areas. To date more than thirty units are installed in different settings around the world. A LAWR was also deployed in the Alps, at 3883 m a.s.l. on the Kl. Matterhorn (Valais, Switzerland). This was the highest LAWR of the world and it led to the development of an Alpine LAWR system that, besides featuring important technological improvements needed to withstand the severe Alpine conditions, required the development of a new Alpine Radar COnversion Model (ARCOM), which is the main focus of this contribution. The LAWR system is equipped with the original FURUNO fan-beam slotted antenna and the original logarithmic receiver, which limits the radar observations to the video signal (L) withour providing the reflectivity (Z). The beam is 0.95 deg wide and 20 deg high. It can detect precipitation to a max range of 60 km. In order to account for the limited availability of raw signal and information and the specific mountain set-up, the conversion model had to be developed differently from the state-of-the-art radar conversion technique used for this class of radars. In particular, the ARCOM is based on a model used to simulate a spatial dependent factor, hereafter called ACF, which is in turn function of parameters that take in account climatological conditions, also used in other conversion methods, but additionally accounting for local radar beam features and for orographic forcings such as the effective sampling power (sP), which is modelled by means of antenna pattern, geometric ground clutter and their interaction. The result is a conversion factor formulated to account for a range correction that is based on the increase of the sampling volume, partial beam blocking and local climatological conditions. The importance of the latter in this study is double with respect to the standard conversion technique for this

  20. Frost resistance in alpine woody plants.

    PubMed

    Neuner, Gilbert

    2014-01-01

    This report provides a brief review of key findings related to frost resistance in alpine woody plant species, summarizes data on their frost resistance, highlights the importance of freeze avoidance mechanisms, and indicates areas of future research. Freezing temperatures are possible throughout the whole growing period in the alpine life zone. Frost severity, comprised of both intensity and duration, becomes greater with increasing elevation and, there is also a greater probability, that small statured woody plants, may be insulated by snow cover. Several frost survival mechanisms have evolved in woody alpine plants in response to these environmental conditions. Examples of tolerance to extracellular freezing and freeze dehydration, life cycles that allow species to escape frost, and freeze avoidance mechanisms can all be found. Despite their specific adaption to the alpine environment, frost damage can occur in spring, while all alpine woody plants have a low risk of frost damage in winter. Experimental evidence indicates that premature deacclimation in Pinus cembra in the spring, and a limited ability of many species of alpine woody shrubs to rapidly reacclimate when they lose snow cover, resulting in reduced levels of frost resistance in the spring, may be particularly critical under the projected changes in climate. In this review, frost resistance and specific frost survival mechanisms of different organs (leaves, stems, vegetative and reproductive over-wintering buds, flowers, and fruits) and tissues are compared. The seasonal dynamics of frost resistance of leaves of trees, as opposed to woody shrubs, is also discussed. The ability of some tissues and organs to avoid freezing by supercooling, as visualized by high resolution infrared thermography, are also provided. Collectively, the report provides a review of the complex and diverse ways that woody plants survive in the frost dominated environment of the alpine life zone. PMID:25520725

  1. Frost resistance in alpine woody plants

    PubMed Central

    Neuner, Gilbert

    2014-01-01

    This report provides a brief review of key findings related to frost resistance in alpine woody plant species, summarizes data on their frost resistance, highlights the importance of freeze avoidance mechanisms, and indicates areas of future research. Freezing temperatures are possible throughout the whole growing period in the alpine life zone. Frost severity, comprised of both intensity and duration, becomes greater with increasing elevation and, there is also a greater probability, that small statured woody plants, may be insulated by snow cover. Several frost survival mechanisms have evolved in woody alpine plants in response to these environmental conditions. Examples of tolerance to extracellular freezing and freeze dehydration, life cycles that allow species to escape frost, and freeze avoidance mechanisms can all be found. Despite their specific adaption to the alpine environment, frost damage can occur in spring, while all alpine woody plants have a low risk of frost damage in winter. Experimental evidence indicates that premature deacclimation in Pinus cembra in the spring, and a limited ability of many species of alpine woody shrubs to rapidly reacclimate when they lose snow cover, resulting in reduced levels of frost resistance in the spring, may be particularly critical under the projected changes in climate. In this review, frost resistance and specific frost survival mechanisms of different organs (leaves, stems, vegetative and reproductive over-wintering buds, flowers, and fruits) and tissues are compared. The seasonal dynamics of frost resistance of leaves of trees, as opposed to woody shrubs, is also discussed. The ability of some tissues and organs to avoid freezing by supercooling, as visualized by high resolution infrared thermography, are also provided. Collectively, the report provides a review of the complex and diverse ways that woody plants survive in the frost dominated environment of the alpine life zone. PMID:25520725

  2. Alpine Groundwater - Pristine Aquifers Under Threat?

    NASA Astrophysics Data System (ADS)

    Schneider, P.; Lange, A.

    2014-12-01

    Glacier and permafrost retreat are prominent climate change indicators. However, the characteristics of climate and hydrology in mountain areas remain poorly understood relative to lowland areas. Specifically, not much is known about alpine groundwater, its recharge and water quality variations, as these remote reservoirs are rarely monitored. As global temperatures rise, glaciers and permafrost will continue to retreat forming new sediment deposits and changing infiltration conditions in high alpine terrain. Climate change impacts the hydro-chemical composition of alpine waters, accelerates weathering processes, and potentially triggers mobilization of pollutants. Accordingly, we monitored groundwater quantity and quality parameters of an alpine porous aquifer near the Tiefenbach glacier in the Gotthard Massif in Switzerland. The goal of this research was to assess quality and seasonal storage dynamics of groundwater above the timberline (2000 m). To translate hydrological science into an ecosystem service context, we focused on four attributes: Water quantity: observations of groundwater level fluctuations combined with analysis of contributing water sources based on stable isotope analysis to give a quantitative understanding of origin and amount of water, Water quality: groundwater level, groundwater temperature and electrical conductivity were used as proxies for sampling of hydro-chemical parameters with automated water samplers during primary groundwater recharge periods (snowmelt and rainfall events), Location: Alpine terrain above the timberline, especially recharge into/out of an alpine porous aquifer at a pro-glacial floodplain and Date of annual melt (albedo effect) and timing of flow (snow- and icemelt from May to September) and groundwater recharge during the growing season. The study found that the summer groundwater temperatures depend on the date of annual melt and are more sensitive to climate forcing than lowland groundwater temperatures

  3. Differential exposure of alpine ospreys to mercury: melting glaciers, hydrology or deposition patterns?

    PubMed

    Guigueno, Mélanie F; Elliott, Kyle H; Levac, Joshua; Wayland, Mark; Elliott, John E

    2012-04-01

    Mercury (Hg) is a global contaminant impacting even remote environments. In alpine watersheds, glacial meltwater is a source of Hg, which accumulated in glaciers during the 1960-1980 cooling cycle. The considerable variation observed for Hg exposure of alpine animals in proximal watersheds could result from differences among those watersheds in Hg loading from glacial meltwater. Alternatively, variation may be the result of hydrology, atmospheric Hg deposition patterns, or food web characteristics. To examine those possibilities, we measured Hg in ospreys (Pandion haliaetus), apex predators in 15 watersheds in western Canada. Mercury levels in feathers of nestlings increased with increasing modeled atmospheric deposition rates and decreased with lake size. In eggs mercury decreased with δ(13)C, an indicator of food web structure, and with pH and elevation. Thus, Hg levels in chicks were strongly associated with local patterns relevant when the chicks were growing (e.g. the period post-snow melt: Hg deposition, lake size) while Hg levels in eggs were weakly associated with local patterns relevant during the snow melt (elevation, δ(13)C), with the remainder of the Hg variation in eggs determined by other factors such as possible Hg accumulation by the adult elsewhere. Modeled atmospheric deposition from prevailing upwind locations including Asia, followed by runoff into small lakes, were related to Hg patterns in osprey, with little apparent role for recent melting of glaciers. Our study highlights the importance of physical patterns to the environmental chemistry of top predators. PMID:22280924

  4. Ductile extension in alpine Corsica

    NASA Astrophysics Data System (ADS)

    Jolivet, Laurent; Dubois, Roland; Fournier, Marc; Goffé, Bruno; Michard, André; Jourdan, Claudie

    1990-10-01

    Ductile deformation in high-pressure (P)-low temperature (T) conditions due to the westward thrusting of oceanic material onto a continental basement in alpine Corsica is overprinted by a late deformation event with a reverse shear sense (eastward) that took place in less severe P-T conditions. We show that the late deformation can be linked to extension during rifting and spreading of the Liguro Provençal basin from late Oligocene to late-middle Miocene time. Major compressive thrust contacts were reactivated as ductile normal faults and, in some units, only a penetrative eastward shear can be observed. This extension following the thickening of the crust brought tectonic units which underwent very different P- T conditions during the earlier stage into close contact. The Balagne nappe, which shows neither significant ductile deformation nor metamorphism, directly overlies the high-P units. The extensional deformation is distributed through the entire thickness of the nappe stack but is more important along the major thrust contacts, which localize the strain. The geometry of the crustal extension is controlled by that of the early compressive thrusts. The latest structures are east-dipping brittle normal faults which bound the early to middle Miocene Saint Florent half graben.

  5. Alpine Corsica Metamorphic Core Complex

    NASA Astrophysics Data System (ADS)

    Fournier, Marc; Jolivet, Laurent; Goffé, Bruno; Dubois, Roland

    1991-12-01

    Alpine Corsica is an example where superficial nonmetamorphic allochtonous units rest upon a highly strained metamorphic complex. Early ductile deformation under high pressure-low temperature (HP-LT) conditions is due to the westward thrusting of oceanic material onto a continental basement as shown by previous studies. New thermobarometric estimates yield minimal peak HP-LT metamorphism conditions of 11 kbar at 400°C. The early deformation is overprinted by a ductile deformation with an eastward sense of shear postdating or contemporaneous with mineral recrystallizations in the greenschist facies conditions. Early compressive thrust contacts are reworked as east dipping ductile normal faults and the less competent units display only eastward shear criteria. The upper units are affected by an extensional brittle deformation, and east dipping brittle normal faults bound to the west the early to middle Miocene Saint-Florent half-graben. The greenschist metamorphic event lasted until 33 Ma, which is contemporaneous with the beginning of the extension in the Liguro-Provençal basin. We interpret the second deformation stage as the result of a ductile extension following the overthickening of the crust due to the westward thrusting. Extension reduces the thickness of the crust so that upper units free from early P-T conditions are brought into close contact with a HP-LT metamorphic core complex. The geometry of the late extension is controlled by that of the early compressive thrust.

  6. Modelling photochemistry in alpine valleys

    NASA Astrophysics Data System (ADS)

    Brulfert, G.; Chemel, C.; Chaxel, E.; Chollet, J. P.

    2005-03-01

    Road traffic is a serious problem in the Chamonix Valley, France: traffic, noise and above all air pollution worry the inhabitants. The big fire in the Mont-Blanc tunnel made it possible, in the framework of the POVA project (POllution in Alpine Valleys), to undertake measurement campaigns with and without heavy-vehicle traffic through the valley, towards Italy (before and after the tunnel re-opening). Modelling in POVA should make it possible to explain the processes leading to episodes of atmospheric pollution, both in summer and in winter. Atmospheric prediction model ARPS 4.5.2 (Advanced Regional Prediction System), developed at the CAPS (Center for Analysis and Prediction of Storms) of the University of Oklahoma, enables to resolve the dynamics above a complex terrain. This model is coupled to the TAPOM 1.5.2 atmospheric chemistry (Transport and Air POllution Model) code developed at the Air and Soil Pollution Laboratory of the Ecole Polytechnique Fédérale de Lausanne. The numerical codes MM5 and CHIMERE are used to compute large scale boundary forcing. Using 300-m grid cells to calculate the dynamics and the reactive chemistry makes possible to accurately represent the dynamics in the valley (slope and valley winds) and to process chemistry at fine scale. Validation of campaign days allows to study chemistry indicators in the valley. NOy according to O3 reduction demonstrates a VOC controlled regime, different from the NOx controlled regime expected and observed in the nearby city of Grenoble.

  7. Altered performance of white sucker populations in the Manitouwadge chain of lakes is associated with changes in benthic macroinvertebrate communities as a result of copper and zinc contamination

    SciTech Connect

    Munkittrick, K.R.; Miller, P.A.; Barton, D.R.; Dixon, D.G. )

    1991-06-01

    White sucker (Catostomus commersoni) collected from the Manitouwadge chain of lakes show a lower growth rate and fecundity in lakes contaminated with copper and zinc from a mixed metal mine. This study evaluated whether the changes in performance of the fish were related to direct impacts of the metals or indirect impacts associated with changes in food availability. Concentrations of metals in the water and sediment of lakes in the Manitouwadge chain were elevated, relative to reference sites. The concentrations of Cu and Zn in the digesta of white sucker were significantly higher, as were the levels of both Cu and Zn in liver, kidney, and gill tissue. Muscle and spleen levels of Cu and Zn were significantly lower or not different from controls. Tissue levels were within the homeostatic range for Cu and Zn. However, the total density of invertebrates varied from greater than 25,000 m-2 at control sites to less than 13,000 m-2 at contaminated sites, and the number of genera recorded was more than 50% lower in shallow water samples. There was almost a complete absence of several invertebrate taxa at contaminated sites, including Plecoptera, Ephemeroptera, Odonata, Trichoptera, Amphipoda, and Unionidae. Diptera accounted for 78 to 96% of the total numbers of individuals at metal-contaminated sites as compared with 40 to 75% at the control sites. An analysis of white sucker stomach contents showed that the contents closely reflected the benthic composition observed in the natural substrate. Changes in food availability and feeding activity were correlated with previous changes documented in the growth, fecundity, and lipid levels of white sucker.

  8. Impacts after four years of experimental trampling on alpine/sub-alpine environments in western Tasmania.

    PubMed

    Whinam, Jennie; Chilcott, Nicole M

    2003-04-01

    Experimental trials were undertaken over four years to assess the impact of recreational trampling in undisturbed alpine and sub-alpine vegetation communities in the Western Arthur Range, western Tasmania. Data on 'pad' formation due to human trampling were collected using vegetation cover assessments, biomass estimates and detailed cross-sectional surface profiles. In sub-alpine buttongrass and alpine herbfield, prolonged and sustained damage may occur after 100 passes by walkers. The environmental threshold of the flat alpine herbfield site was breached after 200 passes. Plant morphology was one determinant of resistance and resilience, with upright woody shrubs and tall tussock graminoids most vulnerable to sustained trampling damage. Cushions are susceptible to trampling impacts at 500 passes. Loss of vegetation cover peaks 6-12 months after trampling. Our results show that pads formed with as few as 30-100 passes per annum and tracks form at between 100 and 500 passes per annum. Two years after the cessation of trampling, there is some small recovery in vegetation cover after 30 and 100 passes per annum applied for three years, but no evidence of recovery at the 500 pass treatments. The low trampling threshold and slow recovery rates in western Tasmania suggest that concentrating walkers on a minimal number of sites may be the best management option for these untracked alpine and sub-alpine environments. PMID:12710922

  9. Multilocus Analyses Reveal Postglacial Demographic Shrinkage of Juniperus morrisonicola (Cupressaceae), a Dominant Alpine Species in Taiwan

    PubMed Central

    Chiu, Chi-Te; Huang, Chao-Li; Hung, Kuo-Hsiang; Chiang, Tzen-Yuh

    2016-01-01

    Postglacial climate changes alter geographical distributions and diversity of species. Such ongoing changes often force species to migrate along the latitude/altitude. Altitudinal gradients represent assemblage of environmental, especially climatic, variable factors that influence the plant distributions. Global warming that triggered upward migrations has therefore impacted the alpine plants on an island. In this study, we examined the genetic structure of Juniperus morrisonicola, a dominant alpine species in Taiwan, and inferred historical, demographic dynamics based on multilocus analyses. Lower levels of genetic diversity in north indicated that populations at higher latitudes were vulnerable to climate change, possibly related to historical alpine glaciers. Neither organellar DNA nor nuclear genes displayed geographical subdivisions, indicating that populations were likely interconnected before migrating upward to isolated mountain peaks, providing low possibilities of seed/pollen dispersal across mountain ranges. Bayesian skyline plots suggested steady population growth of J. morrisonicola followed by recent demographic contraction. In contrast, most lower-elevation plants experienced recent demographic expansion as a result of global warming. The endemic alpine conifer may have experienced dramatic climate changes over the alternation of glacial and interglacial periods, as indicated by a trend showing decreasing genetic diversity with the altitudinal gradient, plus a fact of upward migration. PMID:27561108

  10. Nitrogen Critical Loads for an Alpine Meadow Ecosystem on the Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Zong, Ning; Shi, Peili; Song, Minghua; Zhang, Xianzhou; Jiang, Jing; Chai, Xi

    2016-03-01

    Increasing atmospheric nitrogen (N) deposition has the potential to alter plant diversity and thus the function and stability of terrestrial ecosystems. N-limited alpine ecosystems are expected to be particularly susceptible to increasing N deposition. However, little is known about the critical loads and saturation thresholds of ecosystem responses to increasing N deposition on the Tibetan Plateau, despite its importance to ecosystem management. To evaluate the N critical loads and N saturation thresholds in an alpine ecosystem, in 2010, we treated an alpine meadow with five levels of N addition (0, 10, 20, 40, and 80 kg N ha-1 year-1) and characterized plant and soil responses. The results showed that plant species richness and diversity index did not statistically vary with N addition treatments, but they both changed with years. N addition affected plant cover and aboveground productivity, especially for grasses, and soil chemical features. The N critical loads and saturation thresholds, in terms of plant cover and biomass change at the community level, were 8.8-12.7 and 50 kg N ha-1 year-1 (including the ambient N deposition rate), respectively. However, pronounced changes in soil inorganic N and net N mineralization occurred under the 20 and 40 kg N ha-1 year-1 treatments. Our results indicate that plant community cover and biomass are more sensitive than soil to increasing N inputs. The plant community composition in alpine ecosystems on the Qinghai-Tibetan Plateau may change under increasing N deposition in the future.

  11. Nitrogen Critical Loads for an Alpine Meadow Ecosystem on the Tibetan Plateau.

    PubMed

    Zong, Ning; Shi, Peili; Song, Minghua; Zhang, Xianzhou; Jiang, Jing; Chai, Xi

    2016-03-01

    Increasing atmospheric nitrogen (N) deposition has the potential to alter plant diversity and thus the function and stability of terrestrial ecosystems. N-limited alpine ecosystems are expected to be particularly susceptible to increasing N deposition. However, little is known about the critical loads and saturation thresholds of ecosystem responses to increasing N deposition on the Tibetan Plateau, despite its importance to ecosystem management. To evaluate the N critical loads and N saturation thresholds in an alpine ecosystem, in 2010, we treated an alpine meadow with five levels of N addition (0, 10, 20, 40, and 80 kg N ha(-1) year(-1)) and characterized plant and soil responses. The results showed that plant species richness and diversity index did not statistically vary with N addition treatments, but they both changed with years. N addition affected plant cover and aboveground productivity, especially for grasses, and soil chemical features. The N critical loads and saturation thresholds, in terms of plant cover and biomass change at the community level, were 8.8-12.7 and 50 kg N ha(-1) year(-1) (including the ambient N deposition rate), respectively. However, pronounced changes in soil inorganic N and net N mineralization occurred under the 20 and 40 kg N ha(-1) year(-1) treatments. Our results indicate that plant community cover and biomass are more sensitive than soil to increasing N inputs. The plant community composition in alpine ecosystems on the Qinghai-Tibetan Plateau may change under increasing N deposition in the future. PMID:26475686

  12. Multilocus Analyses Reveal Postglacial Demographic Shrinkage of Juniperus morrisonicola (Cupressaceae), a Dominant Alpine Species in Taiwan.

    PubMed

    Huang, Chi-Chun; Hsu, Tsai-Wen; Wang, Hao-Ven; Liu, Zin-Huang; Chen, Yi-Yen; Chiu, Chi-Te; Huang, Chao-Li; Hung, Kuo-Hsiang; Chiang, Tzen-Yuh

    2016-01-01

    Postglacial climate changes alter geographical distributions and diversity of species. Such ongoing changes often force species to migrate along the latitude/altitude. Altitudinal gradients represent assemblage of environmental, especially climatic, variable factors that influence the plant distributions. Global warming that triggered upward migrations has therefore impacted the alpine plants on an island. In this study, we examined the genetic structure of Juniperus morrisonicola, a dominant alpine species in Taiwan, and inferred historical, demographic dynamics based on multilocus analyses. Lower levels of genetic diversity in north indicated that populations at higher latitudes were vulnerable to climate change, possibly related to historical alpine glaciers. Neither organellar DNA nor nuclear genes displayed geographical subdivisions, indicating that populations were likely interconnected before migrating upward to isolated mountain peaks, providing low possibilities of seed/pollen dispersal across mountain ranges. Bayesian skyline plots suggested steady population growth of J. morrisonicola followed by recent demographic contraction. In contrast, most lower-elevation plants experienced recent demographic expansion as a result of global warming. The endemic alpine conifer may have experienced dramatic climate changes over the alternation of glacial and interglacial periods, as indicated by a trend showing decreasing genetic diversity with the altitudinal gradient, plus a fact of upward migration. PMID:27561108

  13. Response of carbon dioxide emissions to sheep grazing and nitrogen application in an alpine grassland

    NASA Astrophysics Data System (ADS)

    Gong, Y. M.; Mohammat, A.; Liu, X. J.; Li, K. H.; Christie, P.; Fang, F.; Song, W.; Chang, Y. H.; Han, W. X.; Lü, X. T.; Liu, Y. Y.; Hu, Y. K.

    2013-07-01

    Previous work has failed to address fully the response of (autotrophic and heterotrophic) respiration to grazing and nitrogen (N) addition in different ecosystems, particularly in alpine grasslands outside the growing season. From 2010 to 2011, we combined two methods (static closed chambers and a closed dynamic soil CO2 flux system) in a controlled field experiment in an alpine grassland in the Tianshan Mountains. We examined the effects of grazing and N application on ecosystem respiration (Re) both outside (NGS) and during (GS) the growing season and determined the pattern of Re in relation to climate change. There was no significant change in CO2 emissions under grazing or N application. Heterotrophic respiration (Rh) accounted for 78.5% of Re. Re, Rh and autotrophic respiration (Ra) outside the growing season were equivalent to 12.9, 14.1 and 11.4% of the respective CO2 fluxes during the growing season. In addition, our results indicate that precipitation (soil water content) plays a critical role in Ra in this cold and arid environment. Both Rh and Re were sensitive to soil temperature. Moreover, our results suggest that grazing and N addition exert no significant effect on CO2 emissions in alpine grassland but may alter soil carbon stocks in alpine grassland.

  14. Modelling photochemistry in alpine valleys

    NASA Astrophysics Data System (ADS)

    Brulfert, G.; Chemel, C.; Chaxel, E.; Chollet, J. P.

    2005-09-01

    Road traffic is a serious problem in the Chamonix Valley, France: traffic, noise and above all air pollution worry the inhabitants. The big fire in the Mont-Blanc tunnel made it possible, in the framework of the POVA project (POllution in Alpine Valleys), to undertake measurement campaigns with and without heavy-vehicle traffic through the Chamonix and Maurienne valleys, towards Italy (before and after the tunnel re-opening). Modelling is one of the aspects of POVA and should make it possible to explain the processes leading to episodes of atmospheric pollution, both in summer and in winter. Atmospheric prediction model ARPS 4.5.2 (Advanced Regional Prediction System), developed at the CAPS (Center for Analysis and Prediction of Storms) of the University of Oklahoma, enables to resolve the dynamics above a complex terrain. This model is coupled to the TAPOM 1.5.2 atmospheric chemistry (Transport and Air POllution Model) code developed at the Air and Soil Pollution Laboratory of the Ecole Polytechnique Fédérale de Lausanne. The numerical codes MM5 and CHIMERE are used to compute large scale boundary forcing.

    This paper focuses on modelling Chamonix valley using 300-m grid cells to calculate the dynamics and the reactive chemistry which makes possible to accurately represent the dynamics in the Chamonix valley (slope and valley winds) and to process chemistry at fine scale. The summer 2003 intensive campaign was used to validate the model and to study chemistry. NOy according to O3 reduction demonstrates a VOC controlled regime, different from the NOx controlled regime expected and observed in the nearby city of Grenoble.

  15. High-mountain lakes as a hotspot of dissolved organic matter production in a changing climate

    NASA Astrophysics Data System (ADS)

    Abood, P. H.; Williams, M. W.; McKnight, D. M.; Hood, E. H.

    2004-12-01

    Changes in climate may adversely affect mountain environments before downstream ecosystems are affected. Steep topography, thin soils with limited extent, sparse vegetation, short growing seasons, and climatic extremes (heavy snowfalls, cold temperatures, high winds), all contribute to the sensitivity of high mountain environments to perturbations. Here we evaluate the role of oligatrophic high-elevation lakes as "hot spots" of aquatic production that may respond to changes in temperature, precipitation amount, and pollution deposition faster and more directly than co-located terrestrial ecosystems. Our research was conducted in the Rocky Mountains, USA. Water samples were collected for dissolved organic carbon (DOC), other solutes, and water isotopes over the course of the runoff season along a longitudinal transect of North Boulder Creek in the Colorado Front Range from the continental divide and alpine areas to downstream forested systems. Sources of DOC were evaluated using chemical fractionation with XAD-8 resins and fluorescence spectroscopy. There was net DOC production in the two alpine lakes but not for the forested subalpine lake. Oxygen-18 values showed that water residence times in lakes increased dramatically in late summer compared to snowmelt. Chemical fractionation of DOC showed there was a increase in the non-humic acid content across the summer of 2003 at all elevations, with alpine waters showing greater increases than subalpine waters. The fluorescence properties of DOC and water isotopes suggested that DOC in aquatic systems was primarily derived from terrestrial precursor material during snowmelt. However, fluorescence properties of DOC in high-elevation lakes on the recession limb of the hydrograph suggest DOC derived from algal and microbial biomass in the lakes was a more important source of DOC in late summer and fall. Alpine lakes produced 14 times more DOC on unit area basis compared to the surrounding terrestrial ecosystems. We

  16. Changes in alpine wetland ecosystems of the Qinghai-Tibetan plateau from 1967 to 2004.

    PubMed

    Zhang, Yu; Wang, Genxu; Wang, Yibo

    2011-09-01

    Spatiotemporal shifts in the extent and distribution of alpine wetland ecosystems in China's Qinghai-Tibet plateau were investigated for the period 1967-2004. Using aerial photographs for 1967, and satellite remote sensing data for 1986, 2000, and 2004/5, the main components and distribution of alpine wetland ecosystems in the headwaters regions of the Yangtze and Yellow Rivers, as well as those of the nearby Zoige region, were analyzed. Widespread degradation of the Qinghai-Tibet plateau's alpine wetlands occurred between 1967 and 2004, with over 10% of their area being lost. The greatest such degradation occurred in the headwaters region of Yangtze River, where wetland areas shrank by 29%, and the area of dried-up lakes rose by 17.5%. In the Yellow River's headwaters region as well as the Zoige region, wetland ecosystems clearly underwent accelerated fragmentation and isolation in their spatial distribution. The wetlands' degradation was closely correlated to the rise in air temperature, which from 1982-2004 was over 2-fold faster that from 1965-1982. PMID:21140209

  17. RANAVIRUS CAUSES MASS DIE-OFFS OF ALPINE AMPHIBIANS IN THE SOUTHWESTERN ALPS, FRANCE.

    PubMed

    Miaud, Claude; Pozet, Françoise; Gaudin, Nadine Curt Grand; Martel, An; Pasmans, Frank; Labrut, Sophie

    2016-04-28

    Pathogenic fungi and viruses cause mortality outbreaks in wild amphibians worldwide. In the summer of 2012, dead tadpoles and adults of the European common frog Rana temporaria were reported in alpine lakes in the southwestern Alps (Mercantour National Park, France). A preliminary investigation using molecular diagnostic techniques identified a Ranavirus as the potential pathogenic agent. Three mortality events were recorded in the park, and samples were collected. The amphibian chytrid fungus Batrachochytrium dendrobatidis was not detected in any of the dead adult and juvenile frogs sampled (n=16) whereas all specimens were positive for a Ranavirus. The genome sequence of this Ranavirus was identical to previously published sequences of the common midwife toad virus (CMTV), a Ranavirus that has been associated with amphibian mortalities throughout Europe. We cultured virus from the organs of the dead common frogs and infecting adult male common frogs collected in another alpine region where no frog mortality had been observed. The experimentally infected frogs suffered 100% mortality (n=10). The alpine die-off is the first CMTV outbreak associated with mass mortality in wild amphibians in France. We describe the lesions observed and summarize amphibian populations affected by Ranaviruses in Europe. In addition, we discuss the ecologic specificities of mountain amphibians that may contribute to increasing their risk of exposure to and transmission of Ranaviruses. PMID:26967128

  18. Educational and Demographic Profile: Alpine County.

    ERIC Educational Resources Information Center

    California Postsecondary Education Commission, 2004

    2004-01-01

    This profile uniquely presents a variety of educational and socioeconomic information for Alpine County, nearby counties, and the state. The profile highlights the relationship between various factors that affect the economic well-being of individuals and communities. This presentation of information provides a framework for enhanced…

  19. Modeling glacier beds in the Austrian Alps: How many lakes will form in future?

    NASA Astrophysics Data System (ADS)

    Koehler, Dominik; Geilhausen, Martin; Linsbauer, Andreas

    2014-05-01

    Glacial retreat exposes landscapes with relief characteristics greatly differing from the former ice covered surfaces. If glacial retreat exposes natural basins capable of forming proglacial lakes, then the downstream hydrologic and geomorphic systems in such catchments will be significantly altered due to discharge modifications, sediment trapping, decoupling effects and long term sediment storage (e.g. Geilhausen et al. 2013). Further implications are related to hydropower management, tourism and natural hazards. Consequently, sound knowledge of present day glacier beds ("proglacial zones of tomorrow") and in particular the total number, locations and characteristics of overdeepenings are of importance. For Austria, however, this important information about significant future changes of high alpine regions is yet missing. An interdisciplinary research project is currently in preparation to close this gap. This paper presents results of a pilot study. We used a novel GIS-based approach (GlabTop, cf. Linsbauer et al. 2012) to compute approximate glacier beds in the Austrian Alps. GlabTop ('Glacier bed Topography') is based on an empirical relation between average basal shear stress and elevation range of individual glaciers and makes use of digital elevation models (DEM), glacier outlines and branch lines (i.e. a set of lines covering all important glacier branches). DEMs and glacier outlines were derived from the Austrian glacier inventory (1998) and branch lines were manually digitized. The inventory includes 911 glaciers of which 876 (96%) were considered and 35 were excluded due to size restrictions (< 0.01 km²) or insufficient DEM coverage. We found 165 overdeepenings (> 0.01 km²) with the potential of forming proglacial lakes when glacier retreat reveals the bed. The total area and volume of all overdeepenings is approx. 10 km² and 236 Mio m³ respectively and 33 lakes will be larger than 1 km³. A total glacier volume of 16 ± 5 km³ with an average ice

  20. Are endocrine and reproductive biomarkers altered in contaminant-exposed wild male Largemouth Bass (Micropterus salmoides) of Lake Mead, Nevada/Arizona, USA?

    USGS Publications Warehouse

    Goodbred, Steven L.; Patino, Reynaldo; Torres, Leticia; Echols, Kathy R.; Jenkins, Jill A.; Rosen, Michael R.; Orsak, Erik

    2015-01-01

    Male Largemouth Bass were sampled from two locations in Lake Mead (USA), a site influenced by treated municipal wastewater effluent and urban runoff (Las Vegas Bay), and a reference site (Overton Arm). Samples were collected in summer (July '07) and spring (March '08) to assess general health, endocrine and reproductive biomarkers, and compare contaminant body burdens by analyzing 252 organic chemicals. Sperm count and motility were measured in spring. Contaminants were detected at much higher frequencies and concentrations in fish from Las Vegas Bay than Overton Arm. Those with the highest concentrations included PCBs, DDTs, PBDEs, galaxolide, and methyl triclosan. Fish from Las Vegas Bay also had higher Fulton condition factor, hepatosomatic index, and hematocrit, and lower plasma 11-ketotestosterone concentration (KT). Gonadosomatic index (GSI) and sperm motility did not differ between sites, but sperm count was lower by nearly 50% in fish from Las Vegas Bay. A positive association between KT and GSI was identified, but this association was nonlinear. On average, maximal GSI was reached at sub-maximal KT concentrations. In conclusion, the higher concentration of contaminant body burdens coupled with reduced levels of KT and sperm count in fish from Las Vegas Bay suggest that male reproductive condition was influenced by contaminant exposures. Also, the nonlinear KT-GSI association provided a framework to understand why GSI was similar between male bass from both sites despite their large difference in KT, and also suggested the existence of post-gonadal growth functions of KT at high concentrations.

  1. Are endocrine and reproductive biomarkers altered in contaminant-exposed wild male Largemouth Bass (Micropterus salmoides) of Lake Mead, Nevada/Arizona, USA?

    PubMed

    Goodbred, Steven L; Patiño, Reynaldo; Torres, Leticia; Echols, Kathy R; Jenkins, Jill A; Rosen, Michael R; Orsak, Erik

    2015-08-01

    Male Largemouth Bass were sampled from two locations in Lake Mead (USA), a site influenced by treated municipal wastewater effluent and urban runoff (Las Vegas Bay), and a reference site (Overton Arm). Samples were collected in summer (July '07) and spring (March '08) to assess general health, endocrine and reproductive biomarkers, and compare contaminant body burdens by analyzing 252 organic chemicals. Sperm count and motility were measured in spring. Contaminants were detected at much higher frequencies and concentrations in fish from Las Vegas Bay than Overton Arm. Those with the highest concentrations included PCBs, DDTs, PBDEs, galaxolide, and methyl triclosan. Fish from Las Vegas Bay also had higher Fulton condition factor, hepatosomatic index, and hematocrit, and lower plasma 11-ketotestosterone concentration (KT). Gonadosomatic index (GSI) and sperm motility did not differ between sites, but sperm count was lower by nearly 50% in fish from Las Vegas Bay. A positive association between KT and GSI was identified, but this association was nonlinear. On average, maximal GSI was reached at sub-maximal KT concentrations. In conclusion, the higher concentration of contaminant body burdens coupled with reduced levels of KT and sperm count in fish from Las Vegas Bay suggest that male reproductive condition was influenced by contaminant exposures. Also, the nonlinear KT-GSI association provided a framework to understand why GSI was similar between male bass from both sites despite their large difference in KT, and also suggested the existence of post-gonadal growth functions of KT at high concentrations. PMID:25733205

  2. Multiscale Snow/Icemelt Discharge Simulations into Alpine Reservoirs: adding Glacier Dynamics to a Hydrological Model

    NASA Astrophysics Data System (ADS)

    Schueller, Felix; Förster, Kristian; Hanzer, Florian; Huttenlau, Matthias; Marzeion, Ben; Strasser, Ulrich; Achleitner, Stefan; Kirnbauer, Robert

    2015-04-01

    Glacier and snow runoff in high alpine regions is an essential process in hydrological research for its high relevance on lower altitude areas and hydro-power generation. MUSICALS II (Multiscale Snow/Icemelt Discharge Simulations into Alpine Reservoirs) seeks to identify and quantify water availability and runoff in alpine headwater catchments. The focus is on future changes due to glacier retreat, altering the multi-day and seasonal runoff available for hydropower operations. Our aim is to investigate and improve runoff forecasts by coupling the semi-distributed hydrological model HQSim with a simple glacier evolution model. The glacier model MMBM (Marzeion Mass Balance Model) with its statistical nature allows for fast modelling of the dynamical properties of glaciers. We present the design of the coupled hydrological application for different hydro power headwater catchments in Tyrol. The capabilities of the glacier model to simulate the selected glaciers is shown. Simulated discharge with the original and the coupled model are compared to downstream gauge measurements. Using the multi-objective optimization algorithm AMALGAM (A Multi-ALgorithm, Genetically Adaptive Multiobjective model), we optimize the glacier module parameters fully automatically. The results show the improvements in runoff modelling for past periods, when altering of glaciated catchment parts is considered. This indicates consideration of this process is mandatory for simulating future developments.

  3. A Temperate Alpine Glacier as a Reservoir of Polychlorinated Biphenyls: Model Results of Incorporation, Transport, and Release.

    PubMed

    Steinlin, Christine; Bogdal, Christian; Lüthi, Martin P; Pavlova, Pavlina A; Schwikowski, Margit; Zennegg, Markus; Schmid, Peter; Scheringer, Martin; Hungerbühler, Konrad

    2016-06-01

    In previous studies, the incorporation of polychlorinated biphenyls (PCBs) has been quantified in the accumulation areas of Alpine glaciers. Here, we introduce a model framework that quantifies mass fluxes of PCBs in glaciers and apply it to the Silvretta glacier (Switzerland). The models include PCB incorporation into the entire surface of the glacier, downhill transport with the flow of the glacier ice, and chemical fate in the glacial lake. The models are run for the years 1900-2100 and validated by comparing modeled and measured PCB concentrations in an ice core, a lake sediment core, and the glacial streamwater. The incorporation and release fluxes, as well as the storage of PCBs in the glacier increase until the 1980s and decrease thereafter. After a temporary increase in the 2000s, the future PCB release and the PCB concentrations in the glacial stream are estimated to be small but persistent throughout the 21st century. This study quantifies all relevant PCB fluxes in and from a temperate Alpine glacier over two centuries, and concludes that Alpine glaciers are a small secondary source of PCBs, but that the aftermath of environmental pollution by persistent and toxic chemicals can endure for decades. PMID:27164482

  4. An inventory of glacial lakes in the Austrian Alps

    NASA Astrophysics Data System (ADS)

    Buckel, Johannes; Otto, Jan-Christoph; Keuschnig, Markus; Götz, Joachim

    2016-04-01

    The formation of lakes is one of the consequences of glacier retreat due to climate change in mountain areas. Numerous lakes have formed in the past few decades in many mountain regions around the globe. Some of these lakes came into focus due to catastrophic hazard events especially in the Himalayas and the Andes. Glacial lake development and lifetime is controlled by the complex interplay of glacier dynamics, geomorphological process activity and geological boundary conditions. Besides the hazard potential new lakes in formerly glaciated areas will significantly contribute to a new landscape setting and to changing geomorphologic, hydrologic and ecologic conditions at higher alpine altitudes. We present an inventory of high alpine lakes in the Austrian Alps located above an altitude of 1700 m asl. Most of these lakes are assumed to be of glacial origin, but other causes for development, like mass movements are considered as well. The inventory is a central part of the project FUTURELAKES that aims at modelling the potential development of glacial lakes in Austria (we refer to the presentation by Helfricht et al. during the conference for more details on the modelling part). Lake inventory data will serve as one basis for model validation since modelling is performed on different time steps using glacier inventory data. The purpose of the lake inventory is to get new insights into boundary conditions for lake formation and evolution by analysing existing lake settings. Based on these information the project seeks to establish a model of lake sedimentation after glacier retreat in order to assess the potential lifetime of the new lakes in Austria. Lakes with a minimum size of 1000 m² were mapped using multiple aerial imagery sources. The dataset contains information on location, geometry, dam type, and status of sedimentation for each lake. Additionally, various geologic, geomorphic and morphometric parameters describe the lake catchments. Lake data is related to

  5. Intersex and alterations in reproductive development of a cichlid, Tilapia guineensis, from a municipal domestic water supply lake (Eleyele) in Southwestern Nigeria.

    PubMed

    Adeogun, Aina O; Ibor, Oju R; Adeduntan, Sherifat D; Arukwe, Augustine

    2016-01-15

    The objectives of this study were to develop and validate biomarker techniques for aquatic environmental monitoring of endocrine disrupting chemicals (EDCs) in Nigeria aquatic ecosystems, using the Eleyele Lake, which is a major source of domestic water supply to Ibadan and its surrounding towns, as a model aquatic environment and Tilapia guineensis, as a model organism. A total of 55 male and 28 female fish were used for this study. No significant difference in condition factor was observed between the sexes. Evaluation of gross gonadal morphology of the sampled fish showed 33% intersex prevalence in the sampled population, of which respective 71 and 29% were males and females, with visible testis and ovary developing alongside phenotypic females and males. Plasma concentrations of luteinizing hormone (LH), follicle-stimulating hormone (FSH), 11-ketotestosterone (11-KT) and 17β-estradiol (E2) were performed, showing that male fish had significantly higher plasma LH and E2 concentrations, compared to females. Vitellogenin (Vtg) and zona radiata proteins (Zrp) mRNA levels were significantly higher in males, compared to female fish. Contaminant analysis revealed that PCB 81, 123, 138 and 196 were the only PCB congeners detected in sediment and fish muscle (PCB153 in sediment), while dieldrin was the only organochlorine compound (OC) detected in Eleyele sediment. These responses were used in a multivariate analysis, showing that two principal components were extracted and accounted for 74% of total variation in the dataset. The principal component analysis (PCA) showed that male fish variables were positively correlated with PCB congeners 18 and 123, while female fish showed positive correlations with congener 81, 138, 189, 196, indicating sex-specific pattern of association between PCBs concentrations and biomarker expression. In addition, strong positive correlation between male fish and LH, E2, FSH and Vtg was observed, while female fish positively correlated with

  6. Planetary Lake Lander - A Robotic Sentinel to Monitor a Remote Lake

    NASA Technical Reports Server (NTRS)

    Pedersen, Liam; Smith, Trey; Lee, Susan; Cabrol, Nathalie; Rose, Kevin

    2012-01-01

    The Planetary Lake Lander Project is studying the impact of rapid deglaciation at a high altitude alpine lake in the Andes, where disrupted environmental, physical, chemical, and biological cycles result in newly emerging natural patterns. The solar powered Lake Lander robot is designed to monitor the lake system and characterize both baseline characteristics and impacts of disturbance events such as storms and landslides. Lake Lander must use an onboard adaptive science-on-the-fly approach to return relevant data about these events to mission control without exceeding limited energy and bandwidth resources. Lake Lander carries weather sensors, cameras and a sonde that is winched up and down the water column to monitor temperature, dissolved oxygen, turbidity and other water quality parameters. Data from Lake Lander is returned via satellite and distributed to an international team of scientists via web-based ground data systems. Here, we describe the Lake Lander Project scientific goals, hardware design, ground data systems, and preliminary data from 2011. The adaptive science-on-the-fly system will be described in future papers.

  7. Lake Powell

    Atmospheric Science Data Center

    2014-05-15

    article title:  Lake Powell     View Larger Image ... (14.42 mb)   This true-color image over Lake Powell was acquired by Multi-angle Imaging SpectroRadiometer (MISR) in late March 2000. Lake Powell was formed with the construction of the Glen Canyon Dam in 1963, on the ...

  8. CONNECTICUT LAKES

    EPA Science Inventory

    This is a 1:24,000-scale datalayer of named lakes in Connecticut. It is a polygon Shapefile that includes all lakes that are named on the U.S. Geologicial Survey (USGS) 7½ minute topographic quadrangle maps that cover the State of Connecticut, plus other officially named lakes i...

  9. Lake Eyre

    Atmospheric Science Data Center

    2013-04-16

    ...   View Larger Image Lake Eyre is a large salt lake situated between two deserts in one of Australia's driest regions. ... the effect of sunglint at the nadir camera view angle. Dry, salt encrusted parts of the lake appear bright white or gray. Purple areas have ...

  10. Zooplankton Successions in Neighboring Lakes with Contrasting Impacts of Amphibian and Fish Predators

    NASA Astrophysics Data System (ADS)

    Schabetsberger, Robert; Grill, Susanne; Hauser, Gabriele; Wukits, Petra

    2006-06-01

    Two pairs of neighboring subalpine lakes located in the Northern Calcareous Alps of Austria were investigated. Each pair comprised a deeper lake containing European minnows (Phoxinus phoxinus ), and a corresponding shallower lake harboring Alpine newts (Triturus alpestris ) as top predators. Plankton successions within fish and amphibian lakes differed markedly from each other. Throughout the year rotifers numerically dominated within the minnow lakes, while pigmented copepods (Genera Heterocope, Acanthodiaptomus , Arctodiaptomus , Mixodiaptomus ) and Daphnia were prominent in the amphibian lakes, at least early during the ice-free period. We argue that size-selective predation by minnows was the ultimate reason for this predominance of smaller zooplankton. While one of the minnow lakes was characterized by a succession of spatially and temporally segregated rotifer species, the other minnow lake permitted the development of populations of small-sized Bosmina and Ceriodaphnia during summer, probably due to the existence of a strong oxycline allowing zooplankton crustaceans to avoid predation from shore-based shoals of minnows. Once trout were introduced into this lake, minnows were visibly reduced in abundance. Bosmina and Ceriodaphnia disappeared and Daphnia together with a predacious copepod (Heterocope ) emerged either from egg banks or arrived from nearby source populations. We argue that the crustacean communities within the fishless lakes were adapted to the comparatively weak predation rates of Alpine newts.

  11. Effects of acidic deposition on in-lake phosphorus availability: a lesson from lakes recovering from acidification.

    PubMed

    Kopáček, Jiří; Hejzlar, Josef; Kaňa, Jiří; Norton, Stephen A; Stuchlík, Evžen

    2015-03-01

    Lake water concentrations of phosphorus (P) recently increased in some mountain areas due to elevated atmospheric input of P rich dust. We show that increasing P concentrations also occur during stable atmospheric P inputs in central European alpine lakes recovering from atmospheric acidification. The elevated P availability in the lakes results from (1) increasing terrestrial export of P accompanying elevated leaching of dissolved organic carbon and decreasing phosphate-adsorption ability of soils due to their increasing pH, and (2) decreasing in-lake P immobilization by aluminum (Al) hydroxide due to decreasing leaching of ionic Al from the recovering soils. The P availability in the recovering lakes is modified by the extent of soil acidification, soil composition, and proportion of till and meadow soils in the catchment. These mechanisms explain several conflicting observations of the acid rain effects on surface water P concentrations. PMID:25660534

  12. Climate change forces new ecological states in tropical Andean lakes.

    PubMed

    Michelutti, Neal; Wolfe, Alexander P; Cooke, Colin A; Hobbs, William O; Vuille, Mathias; Smol, John P

    2015-01-01

    Air temperatures in the tropical Andes have risen at an accelerated rate relative to the global average over recent decades. However, the effects of climate change on Andean lakes, which are vital to sustaining regional biodiversity and serve as an important water resource to local populations, remain largely unknown. Here, we show that recent climate changes have forced alpine lakes of the equatorial Andes towards new ecological and physical states, in close synchrony to the rapid shrinkage of glaciers regionally. Using dated sediment cores from three lakes in the southern Sierra of Ecuador, we record abrupt increases in the planktonic thalassiosiroid diatom Discostella stelligera from trace abundances to dominance within the phytoplankton. This unprecedented shift occurs against the backdrop of rising temperatures, changing atmospheric pressure fields, and declining wind speeds. Ecological restructuring in these lakes is linked to warming and/or enhanced water column stratification. In contrast to seasonally ice-covered Arctic and temperate alpine counterparts, aquatic production has not increased universally with warming, and has even declined in some lakes, possibly because enhanced thermal stability impedes the re-circulation of hypolimnetic nutrients to surface waters. Our results demonstrate that these lakes have already passed important ecological thresholds, with potentially far-reaching consequences for Andean water resources. PMID:25647018

  13. Climate Change Forces New Ecological States in Tropical Andean Lakes

    PubMed Central

    Michelutti, Neal; Wolfe, Alexander P.; Cooke, Colin A.; Hobbs, William O.; Vuille, Mathias; Smol, John P.

    2015-01-01

    Air temperatures in the tropical Andes have risen at an accelerated rate relative to the global average over recent decades. However, the effects of climate change on Andean lakes, which are vital to sustaining regional biodiversity and serve as an important water resource to local populations, remain largely unknown. Here, we show that recent climate changes have forced alpine lakes of the equatorial Andes towards new ecological and physical states, in close synchrony to the rapid shrinkage of glaciers regionally. Using dated sediment cores from three lakes in the southern Sierra of Ecuador, we record abrupt increases in the planktonic thalassiosiroid diatom Discostella stelligera from trace abundances to dominance within the phytoplankton. This unprecedented shift occurs against the backdrop of rising temperatures, changing atmospheric pressure fields, and declining wind speeds. Ecological restructuring in these lakes is linked to warming and/or enhanced water column stratification. In contrast to seasonally ice-covered Arctic and temperate alpine counterparts, aquatic production has not increased universally with warming, and has even declined in some lakes, possibly because enhanced thermal stability impedes the re-circulation of hypolimnetic nutrients to surface waters. Our results demonstrate that these lakes have already passed important ecological thresholds, with potentially far-reaching consequences for Andean water resources. PMID:25647018

  14. Contexts for change in alpine tundra

    USGS Publications Warehouse

    Malanson, George P.; Rose, Jonathan P.; Schroeder, P. Jason; Fagre, Daniel B.

    2011-01-01

    Because alpine tundra is responding to climate change, a need exists to understand the meaning of observed changes. To provide context for such interpretation, the relevance of niche and neutral theories of biogeography and the continuum and classification approaches to biogeographic description are assessed. Two extensive studies of alpine tundra, from the Indian Peaks area, Colorado and Glacier National Park, Montana, are combined. The data are ordinated to describe relations. The pattern that emerges is one of a continuum of vegetation, but with the distinctions one might expect from distant sites. The relationships of the similarity of vegetation on all possible pairs of sites to the environmental differences and geographic distances are analyzed using Mantel correlations. Because distance and environmental differences in climate between the two sites are correlated, partial correlations are weak but still significant. More advanced analyses are suggested for this environment prior to interpretation of monitoring efforts such as GLORIA.

  15. Sensitivity of subalpine tree seedlings and alpine plants to natural and manipulated climate variation: Initial results from an Alpine Treeline Warming Experiment (Invited)

    NASA Astrophysics Data System (ADS)

    Kueppers, L. M.

    2010-12-01

    Niche models and paleoecological studies indicate that future climate change will alter the geographic distributions of plant species. Changes in temperature, snowmelt timing, or moisture conditions at one edge of a species’ range may have different consequences for recruitment, carbon exchange, phenology, and survival than changes at another edge. Similarly, local genetic adaptation may constrain species and community responses to climate change. We have established a new experiment to investigate potential shifts in the distribution of subalpine tree species, and the alpine species they might replace. We are asking how tree species recruitment and alpine species growth and reproduction vary within their current ranges, and in response to temperature and soil moisture manipulations. We are also examining whether genetic provenance and ecosystem processes constrain tree seedling and alpine herb responses. Our Alpine Treeline Warming Experiment is located across three sites at Niwot Ridge, CO, ranging from near the lower limit of subalpine forest to alpine tundra. We use infrared heaters to raise growing season surface soil temperatures by 4-5°C, and to lengthen the growing season. The warming treatment is crossed with a soil moisture manipulation to distinguish effects due to higher temperatures from those due to drier soil. Each plot is a common garden sown with high and low elevation provenances of limber pine (Pinus flexilis) and Engelmann spruce (Picea engelmannii). We established an additional set of experimental plots to examine treatment effects on alpine species phenology, growth and reproduction. Under ambient conditions in 2009, tree seedling germination rate, lifespan, and first season survival was higher within the species’ current range than in the alpine, and for Engelmann spruce, was higher at the low elevation limit than the high elevation limit. Source population (low vs. high elevation) was a significant factor explaining natural variation in

  16. Alpine Soils as long-term Bioindicators

    NASA Astrophysics Data System (ADS)

    Nestroy, O.

    2009-04-01

    Alpine soils as long-term bioindicators The introductory words concern the definitions and peculiarities of alpine soils and their position in the Austrian Soil Classification 2000 in comparison with the World Reference Base for Soil Resources 2006. The important parameters for genesis and threats for these soils in steep and high positions are discussed. It must be emphasized that the main threats are the very different kinds of erosion e.g. by water, wind and snow, and also by skiing (end of season) as well as and mountain-biking (mainly summer-sport). Due the very slow regeneration and - in this connection - due to the very slow changes of the soil entities, these soils give an utmost importance as a long-time bioindicator. With regard to the climate change one can assume an increase in the content of organic matter on site, but also an increase of erosion and mass movement on the other site, e. g. in kind of "plaiken" (soil slide) as result of an increasing intensity of rainfall. It lies partly in our hands to diminish the number and the intensity of the threats, we can influence the soil development, but the result to reach a new ecological equilibrium is very long - in case of alpine soil more than two generations.

  17. Working toward integrated models of alpine plant distribution

    PubMed Central

    Carlson, Bradley Z.; Randin, Christophe F.; Boulangeat, Isabelle; Lavergne, Sébastien; Thuiller, Wilfried; Choler, Philippe

    2014-01-01

    Species distribution models (SDMs) have been frequently employed to forecast the response of alpine plants to global changes. Efforts to model alpine plant distribution have thus far been primarily based on a correlative approach, in which ecological processes are implicitly addressed through a statistical relationship between observed species occurrences and environmental predictors. Recent evidence, however, highlights the shortcomings of correlative SDMs, especially in alpine landscapes where plant species tend to be decoupled from atmospheric conditions in micro-topographic habitats and are particularly exposed to geomorphic disturbances. While alpine plants respond to the same limiting factors as plants found at lower elevations, alpine environments impose a particular set of scale-dependent and hierarchical drivers that shape the realized niche of species and that require explicit consideration in a modelling context. Several recent studies in the European Alps have successfully integrated both correlative and process-based elements into distribution models of alpine plants, but for the time being a single integrative modelling framework that includes all key drivers remains elusive. As a first step in working toward a comprehensive integrated model applicable to alpine plant communities, we propose a conceptual framework that structures the primary mechanisms affecting alpine plant distributions. We group processes into four categories, including multi-scalar abiotic drivers, gradient dependent species interactions, dispersal and spatial–temporal plant responses to disturbance. Finally, we propose a methodological framework aimed at developing an integrated model to better predict alpine plant distribution. PMID:24790594

  18. Working toward integrated models of alpine plant distribution.

    PubMed

    Carlson, Bradley Z; Randin, Christophe F; Boulangeat, Isabelle; Lavergne, Sébastien; Thuiller, Wilfried; Choler, Philippe

    2013-10-01

    Species distribution models (SDMs) have been frequently employed to forecast the response of alpine plants to global changes. Efforts to model alpine plant distribution have thus far been primarily based on a correlative approach, in which ecological processes are implicitly addressed through a statistical relationship between observed species occurrences and environmental predictors. Recent evidence, however, highlights the shortcomings of correlative SDMs, especially in alpine landscapes where plant species tend to be decoupled from atmospheric conditions in micro-topographic habitats and are particularly exposed to geomorphic disturbances. While alpine plants respond to the same limiting factors as plants found at lower elevations, alpine environments impose a particular set of scale-dependent and hierarchical drivers that shape the realized niche of species and that require explicit consideration in a modelling context. Several recent studies in the European Alps have successfully integrated both correlative and process-based elements into distribution models of alpine plants, but for the time being a single integrative modelling framework that includes all key drivers remains elusive. As a first step in working toward a comprehensive integrated model applicable to alpine plant communities, we propose a conceptual framework that structures the primary mechanisms affecting alpine plant distributions. We group processes into four categories, including multi-scalar abiotic drivers, gradient dependent species interactions, dispersal and spatial-temporal plant responses to disturbance. Finally, we propose a methodological framework aimed at developing an integrated model to better predict alpine plant distribution. PMID:24790594

  19. Geomorphic controls on Pleistocene knickpoint migration in Alpine valleys

    NASA Astrophysics Data System (ADS)

    Leith, Kerry; Fox, Matt; Moore, Jeffrey R.; Brosda, Julian; Krautblatter, Michael; Loew, Simon

    2014-05-01

    Recent insights into sub-glacial bedrock stress conditions suggest that the erosional efficiency of glaciers may reduce markedly following a major erosional cycle [Leith et al., 2013]. This implies that the formation of large glacial valleys within the Alps is likely to have occurred shortly after the onset of 100 ky glacial-interglacial cycles (at the mid-Pleistocene Revolution (MPR)). The majority of landscape change since this time may have therefore been driven by sub-aerial processes. This hypothesis is supported by observations of hillslope and channel morphology within Canton Valais (Switzerland), where major tributary valleys display a common morphology along their length, hinting at a shared geomorphic history. Glaciers currently occupy the headwaters of many catchments, while the upper reaches of rivers flow across extensive alluvial planes before abruptly transitioning to steep channels consisting of mixed bedrock and talus fan deposits. The rivers then converge to flow out over the alluvial plane of the Rhone Valley. Characteristically rough topographies within the region are suggested to mark the progressive transition from a glacial to fluvially-dominated landscape, and correlate well with steepened river channel sections determined from a 2.5 m resolution LiDAR DEM. We envisage a landscape in which ongoing tectonic uplift drives the emergence of Alpine bedrock through massive sedimentary valley infills (currently concentrated in the Rhone Valley), whose elevation is fixed by the consistent fluvial baselevel at Lake Geneva. As fluvial incision ceases at the onset of glaciation, continued uplift causes the formation of knickpoints at the former transition from bedrock to sedimentary infill. These knickpoints will then propagate upstream during subsequent interglacial periods. By investigating channel morphologies using an approach based on the steady-state form of the stream power equation, we can correlate steepened channel reaches (degraded

  20. Soil Fauna Affects Dissolved Carbon and Nitrogen in Foliar Litter in Alpine Forest and Alpine Meadow.

    PubMed

    Liao, Shu; Yang, Wanqin; Tan, Yu; Peng, Yan; Li, Jun; Tan, Bo; Wu, Fuzhong

    2015-01-01

    Dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) are generally considered important active biogeochemical pools of total carbon and nitrogen. Many studies have documented the contributions of soil fauna to litter decomposition, but the effects of the soil fauna on labile substances (i.e., DOC and TDN) in litter during early decomposition are not completely clear. Therefore, a field litterbag experiment was carried out from 13th November 2013 to 23rd October 2014 in an alpine forest and an alpine meadow located on the eastern Tibetan Plateau. Litterbags with different mesh sizes were used to provide access to or prohibit the access of the soil fauna, and the concentrations of DOC and TDN in the foliar litter were measured during the winter (the onset of freezing, deep freezing and thawing stage) and the growing season (early and late). After one year of field incubation, the concentration of DOC in the litter significantly decreased, whereas the TDN concentration in the litter increased. Similar dynamic patterns were detected under the effects of the soil fauna on both DOC and TDN in the litter between the alpine forest and the alpine meadow. The soil fauna showed greater positive effects on decreasing DOC concentration in the litter in the winter than in the growing season. In contrast, the dynamics of TND in the litter were related to seasonal changes in environmental factors, rather than the soil fauna. In addition, the soil fauna promoted a decrease in litter DOC/TDN ratio in both the alpine forest and the alpine meadow throughout the first year of decomposition, except for in the late growing season. These results suggest that the soil fauna can promote decreases in DOC and TDN concentrations in litter, contributing to early litter decomposition in these cold biomes. PMID:26406249

  1. Soil Fauna Affects Dissolved Carbon and Nitrogen in Foliar Litter in Alpine Forest and Alpine Meadow

    PubMed Central

    Liao, Shu; Yang, Wanqin; Tan, Yu; Peng, Yan; Li, Jun; Tan, Bo; Wu, Fuzhong

    2015-01-01

    Dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) are generally considered important active biogeochemical pools of total carbon and nitrogen. Many studies have documented the contributions of soil fauna to litter decomposition, but the effects of the soil fauna on labile substances (i.e., DOC and TDN) in litter during early decomposition are not completely clear. Therefore, a field litterbag experiment was carried out from 13th November 2013 to 23rd October 2014 in an alpine forest and an alpine meadow located on the eastern Tibetan Plateau. Litterbags with different mesh sizes were used to provide access to or prohibit the access of the soil fauna, and the concentrations of DOC and TDN in the foliar litter were measured during the winter (the onset of freezing, deep freezing and thawing stage) and the growing season (early and late). After one year of field incubation, the concentration of DOC in the litter significantly decreased, whereas the TDN concentration in the litter increased. Similar dynamic patterns were detected under the effects of the soil fauna on both DOC and TDN in the litter between the alpine forest and the alpine meadow. The soil fauna showed greater positive effects on decreasing DOC concentration in the litter in the winter than in the growing season. In contrast, the dynamics of TND in the litter were related to seasonal changes in environmental factors, rather than the soil fauna. In addition, the soil fauna promoted a decrease in litter DOC/TDN ratio in both the alpine forest and the alpine meadow throughout the first year of decomposition, except for in the late growing season. These results suggest that the soil fauna can promote decreases in DOC and TDN concentrations in litter, contributing to early litter decomposition in these cold biomes. PMID:26406249

  2. Solar and atmospheric forcing on mountain lakes.

    PubMed

    Luoto, Tomi P; Nevalainen, Liisa

    2016-10-01

    We investigated the influence of long-term external forcing on aquatic communities in Alpine lakes. Fossil microcrustacean (Cladocera) and macrobenthos (Chironomidae) community variability in four Austrian high-altitude lakes, determined as ultra-sensitive to climate change, were compared against records of air temperature, North Atlantic Oscillation (NAO) and solar forcing over the past ~400years. Summer temperature variability affected both aquatic invertebrate groups in all study sites. The influence of NAO and solar forcing on aquatic invertebrates was also significant in the lakes except in the less transparent lake known to have remained uniformly cold during the past centuries due to summertime snowmelt input. The results suggest that external forcing plays an important role in these pristine ecosystems through their impacts on limnology of the lakes. Not only does the air temperature variability influence the communities but also larger-scale external factors related to atmospheric circulation patterns and solar activity cause long-term changes in high-altitude aquatic ecosystems, through their connections to hydroclimatic conditions and light environment. These findings are important in the assessment of climate change impacts on aquatic ecosystems and in greater understanding of the consequences of external forcing on lake ontogeny. PMID:27220094

  3. Subsurface architecture of two tropical alpine desert cinder cones that hold water

    NASA Astrophysics Data System (ADS)

    Leopold, Matthias; Morelli, Amanda; Schorghofer, Norbert

    2016-06-01

    Basaltic lava is generally porous and cannot hold water to form lakes. Here we investigate two impermeable cinder cones in the alpine desert of Maunakea volcano, Hawaii. We present the results of the first ever geophysical survey of the area around Lake Waiau, the highest lake on the Hawaiian Islands, and establish the existence of a second body of standing water in a nearby cinder cone, Pu`upōhaku (~4000 m above sea level), which has a sporadic pond of water. Based on unpublished field notes from Alfred Woodcock (*1905-†2005) spanning the years 1966-1977, more recent observations, and our own geophysical survey using electric resistivity tomography, we find that perched groundwater resides in the crater perennially to a depth of 2.5 m below the surface. Hence, Pu`upōhaku crater hosts a previously unrecognized permanent body of water, the highest on the Hawaiian Islands. Nearby Lake Waiau is also perched within a cinder cone known as Pu`uwaiau. Among other hypotheses, permafrost or a massive block of lava were discussed as a possible cause for perching the water table. Based on our results, ground temperatures are too high and specific electric resistivity values too low to be consistent with either ice-rich permafrost or massive rock. Fine-grained material such as ash and its clay-rich weathering products are likely the impermeable material that explains the perched water table at both study sites. At Pu`uwaiau we discovered a layer of high conductivity that may constitute a significant water reservoir outside of the lake and further be responsible for perching the water toward the lake.

  4. Factors influencing legacy pollutant accumulation in alpine osprey: biology, topography, or melting glaciers?

    PubMed

    Elliott, John E; Levac, Joshua; Guigueno, Mélanie F; Shaw, D Patrick; Wayland, Mark; Morrissey, Christy A; Muir, Derek C G; Elliott, Kyle H

    2012-09-01

    Persistent organic pollutants (POPs) can be transported long distances and deposited into alpine environments via cold trapping and snow scavenging processes. Here we examined biotic and abiotic factors determining contaminant variability of wildlife in alpine ecosystems. We measured POPs in eggs and plasma of an apex predator, the osprey (Pandion haliaetus) breeding in 15 mountainous watersheds across a broad latitudinal, longitudinal and altitudinal range in western Canada. After accounting for proximate biotic factors such as trophic level (δ(15)N) and carbon source (δ(13)C), variability in contaminant concentrations, including ΣDDT (sum of trichlorodiphenylethane-related compounds), toxaphene, hexachlorobenzene (HCB), total chlordane, and ΣPCBs (polychlorinated biphenyls) in osprey tissues was explained by interactions among relative size of watersheds, water bodies, elevation, and glacial input. ΣDDT in nestling plasma, for example, decreased with lake elevation, probably as a result of local past inputs from agricultural or public health usage at lower altitude sites. In contrast, toxaphene, never used as an insecticide in western Canada, increased with elevation and year-round snow and ice cover in both plasma and eggs, indicating long-range atmospheric sources as dominant for toxaphene. Lower chlorinated PCBs in plasma tended to decrease with elevation and ice cover consistent with published data and model outcomes. Temporal trends of POPs in osprey eggs are coincident with some modeled predictions of release from melting glaciers due to climate change. Currently we suggest that contaminants largely are released through annual snowpack melt and deposited in large lower elevation lakes, or some smaller lakes with poor drainage. Our study highlights the importance of understanding how biological processes integrate physical when studying the environmental chemistry of wildlife. PMID:22876912

  5. High intensity training and energy production during 90-second box jump in junior alpine skiers.

    PubMed

    Gross, Micah; Hemund, Kevin; Vogt, Michael

    2014-06-01

    Alpine ski races can last up to 2.5 minutes and have very high metabolic demands. One limiting factor for performance is insufficient aerobic energy supply. We studied the effects of an 8-day interval training block on aerobic capacity (VO2max) and performance and physiology during the 90-second box jump test (BJ90), a maximal performance test employed to simulate the metabolic demands of alpine ski racing, in elite junior skiers. After 10 high-intensity interval training sessions, performed as cycling, running, or an obstacle course, VO2max increased in all subjects by 2.5 ± 1.9 ml · minute(-1) · kg(-1) (4.3 ± 3.2%), as did maximal blood lactate concentration in a graded cycling test (before: 11.7 ± 1.3 mmol · L(-1), after: 14.8 ± 1.8 mmol · L(-1), both parameters p ≤ 0.05). Performance (total jumps) and aerobic energy contribution (63.3 ± 2.8%) during the BJ90 did not increase as hypothesized; however, subjects altered their pacing strategy, which may have counteracted such an effect. Additionally, the present data support the practicality of the performance test used for mimicking the demands of alpine skiing. PMID:24276296

  6. Ecosystem Carbon Storage in Alpine Grassland on the Qinghai Plateau.

    PubMed

    Liu, Shuli; Zhang, Fawei; Du, Yangong; Guo, Xiaowei; Lin, Li; Li, Yikang; Li, Qian; Cao, Guangmin

    2016-01-01

    The alpine grassland ecosystem can sequester a large quantity of carbon, yet its significance remains controversial owing to large uncertainties in the relative contributions of climate factors and grazing intensity. In this study we surveyed 115 sites to measure ecosystem carbon storage (both biomass and soil) in alpine grassland over the Qinghai Plateau during the peak growing season in 2011 and 2012. Our results revealed three key findings. (1) Total biomass carbon density ranged from 0.04 for alpine steppe to 2.80 kg C m-2 for alpine meadow. Median soil organic carbon (SOC) density was estimated to be 16.43 kg C m-2 in alpine grassland. Total ecosystem carbon density varied across sites and grassland types, from 1.95 to 28.56 kg C m-2. (2) Based on the median estimate, the total carbon storage of alpine grassland on the Qinghai Plateau was 5.14 Pg, of which 94% (4.85 Pg) was soil organic carbon. (3) Overall, we found that ecosystem carbon density was affected by both climate and grazing, but to different extents. Temperature and precipitation interaction significantly affected AGB carbon density in winter pasture, BGB carbon density in alpine meadow, and SOC density in alpine steppe. On the other hand, grazing intensity affected AGB carbon density in summer pasture, SOC density in alpine meadow and ecosystem carbon density in alpine grassland. Our results indicate that grazing intensity was the primary contributing factor controlling carbon storage at the sites tested and should be the primary consideration when accurately estimating the carbon storage in alpine grassland. PMID:27494253

  7. Ecosystem Carbon Storage in Alpine Grassland on the Qinghai Plateau

    PubMed Central

    Liu, Shuli; Zhang, Fawei; Du, Yangong; Guo, Xiaowei; Lin, Li; Li, Yikang; Li, Qian; Cao, Guangmin

    2016-01-01

    The alpine grassland ecosystem can sequester a large quantity of carbon, yet its significance remains controversial owing to large uncertainties in the relative contributions of climate factors and grazing intensity. In this study we surveyed 115 sites to measure ecosystem carbon storage (both biomass and soil) in alpine grassland over the Qinghai Plateau during the peak growing season in 2011 and 2012. Our results revealed three key findings. (1) Total biomass carbon density ranged from 0.04 for alpine steppe to 2.80 kg C m-2 for alpine meadow. Median soil organic carbon (SOC) density was estimated to be 16.43 kg C m-2 in alpine grassland. Total ecosystem carbon density varied across sites and grassland types, from 1.95 to 28.56 kg C m-2. (2) Based on the median estimate, the total carbon storage of alpine grassland on the Qinghai Plateau was 5.14 Pg, of which 94% (4.85 Pg) was soil organic carbon. (3) Overall, we found that ecosystem carbon density was affected by both climate and grazing, but to different extents. Temperature and precipitation interaction significantly affected AGB carbon density in winter pasture, BGB carbon density in alpine meadow, and SOC density in alpine steppe. On the other hand, grazing intensity affected AGB carbon density in summer pasture, SOC density in alpine meadow and ecosystem carbon density in alpine grassland. Our results indicate that grazing intensity was the primary contributing factor controlling carbon storage at the sites tested and should be the primary consideration when accurately estimating the carbon storage in alpine grassland. PMID:27494253

  8. Generating quantitative palaeoflood data from homogeneous lake sediments: a case-study from Brotherswater, northwest England

    NASA Astrophysics Data System (ADS)

    Schillereff, Daniel; Chiverrell, Richard; Macdonald, Neil; Hooke, Janet

    2016-04-01

    The scarcity of long-term hydrological data is a barrier to reliably determining the likelihood of floods becoming more frequent and/or intense in a warmer world. Lakes and their sediments are increasingly being used to reconstruct long-term, highly-resolved datasets of past floods but the ultimate goal, generating quantitative palaeohydrological data to augment flood frequency analyses, is a persistent challenge. To this end, ascertaining the autogenic and allogenic processes influencing the character and preservation potential of palaeoflood laminations and determining the minimum discharge at which a sedimentary imprint will be deposited in a particular system are two key precursors. Some success has been achieved at lakes containing annually-laminated sequences or where event layers exhibit well-defined lithological contacts. Many non-alpine and non-polar lakes, especially those in temperate regions, are instead characterised by visually-homogeneous, organic-rich sediments from which discrete flood laminations are difficult to discriminate. Working at Brotherswater, a small upland lake in northwest England, we have successfully demonstrated an approach to obtain flood frequency and magnitude data from this type of lake system by integrating a 16 month sediment trap deployment (CE 2013-2014) with the recent (CE 1962 - 2014) depositional record. The geochemical composition and end-member modelling of the trap data shed light on the seasonal variation in background sedimentation dynamics, specifically enhanced sediment supply during winter, spring diatom blooms and heightened summer productivity, which alter the signature of coarse-grained deposition in response to higher flows. Having pinpointed the characteristic flood end-member, comparison of the short-core palaeoflood reconstruction to local river discharge data was able to reveal the hydrological thresholds of this system: flood magnitudes calculated to have a four year recurrence interval are preserved in

  9. Hydrology of Lake Carroll, Hillsborough County, Florida

    USGS Publications Warehouse

    Henderson, S.E.; Hayes, R.D.; Stoker, Y.E.

    1985-01-01

    Lakeshore property around Lake Carroll has undergone extensive residential development since 1960. This development increased the lake shoreline, altered surface water flow to and from the lake, and may have affected lake-stage characteristics. Some areas of the lake were dredged to provide fill material for lakefront property. Water-balance analyses for 1952-60, a predevelopment period, and 1961-80, a period of residential development, indicate that both net surface water flow to the lake and downward leakage from the lake to the Floridan aquifer were greater after 1960. These changes were due more to changes in the regional climate and related changes in ground-water levels than to changes associated with residential development. Results of water quality analyses in 1980-81 are within State limits for surface waters used for recreation and wildlife propagation. (USGS)

  10. Alpine and pre-Alpine magmatism in the root-zone of the western Central Alps

    NASA Astrophysics Data System (ADS)

    Romer, R. L.; Schärer, U.; Steck, Albrecht

    1996-03-01

    The highest grade of metamorphism and associated structural elements in orogenic belts may be inherited from earlier orogenic events. We illustrate this point using magmatic and metamorphic rocks from the southern steep belt of the Lepontine Gneiss Dome (Central Alps). The U-Pb zircon ages from an anatectic granite at Verampio and migmatites at Corcapolo and Lavertezzo yield 280 290 Ma, i.e., Hercynian ages. These ages indicate that the highest grade of metamorphism in several crystalline nappes of the Lepontine Gneiss Dome is pre-Alpine. Alpine metamorphism reached sufficiently high grade to reset the Rb-Sr and K-Ar systematics of mica and amphibole, but generally did not result in crustal melting, except in the steep belt to the north of the Insubric Line, where numerous 29 to 26 Ma old pegmatites and aplites had intruded syn- and post-kinematically into gneisses of the ductile Simplon Shear Zone. The emplacement age of these pegmatites gives a minimum estimate for the age of the Alpine metamorphic peak in the Monte Rosa nappe. The U-Pb titanite ages of 33 to 31 Ma from felsic porphyritic veins represent a minimum-age estimate for Alpine metamorphism in the Sesia Zone. A porphyric vein emplaced at 448±5 Ma (U-Pb monazite) demonstrates that there existed a consolidated Caledonian basement in the Sesia Zone.

  11. Water resources: Research network to track alpine water

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The water cycle in alpine environments worldwide supplies fresh water to vast downstream areas inhabited by more than half of humanity. The International Network for Alpine Research Catchment Hydrology (INARCH) was launched this year by the Global Energy and Water Exchanges project of the World Clim...

  12. Lake-floor sediment texture and composition of a hydrothermally-active, volcanic lake, Lake Rotomahana

    NASA Astrophysics Data System (ADS)

    Pittari, A.; Muir, S. L.; Hendy, C. H.

    2016-03-01

    Young volcanic lakes undergo a transition from rapid, post-eruptive accumulation of volcaniclastic sediment to slower pelagic settling under stable lake conditions, and may also be influenced by sublacustrine hydrothermal systems. Lake Rotomahana is a young (129 year-old), hydrothermally-active, volcanic lake formed after the 1886 Tarawera eruption, and provides a unique insight into the early evolution of volcanic lake systems. Lake-bottom sediment cores, 20-46 cm in length, were taken along a transect across the lake and characterised with respect to stratigraphy, facies characteristics (i.e., grain size, componentry) and pore water silica concentrations. The sediments generally comprise two widespread facies: (i) a lower facies of light grey to grey, very fine lacustrine silt derived from the unconsolidated pyroclastic deposits that mantled the catchment area immediately after the eruption, which were rapidly reworked and redeposited into the lake basin; and (ii) an upper facies of dark, fine-sandy diatomaceous silt, that settled from the pelagic zone of the physically stable lake. Adjacent to sublacustrine hydrothermal vents, the upper dark facies is absent, and the upper part of the light grey to grey silt is replaced by a third localised facies comprised of hydrothermally altered pale yellow to yellowish brown, laminated silt with surface iron-rich encrustations. Microspheres, which are thought to be composed of amorphous silica, although some may be halloysite, have precipitated from pore water onto sediment grains, and are associated with a decrease in pore water silicon concentration. Lake Rotomahana is an example of a recently-stabilised volcanic lake, with respect to sedimentation, that shows signs of early sediment silicification in the presence of hydrothermal activity.

  13. Geochemical Characterisation of the Alpine Fault Zone from the DFDP Boreholes

    NASA Astrophysics Data System (ADS)

    Menzies, C. D.; Teagle, D. A. H.; Boulton, C. J.; Toy, V.; Townend, J.; Sutherland, R.

    2015-12-01

    The Alpine Fault of the South Island, New Zealand marks the active transpressional boundary between the Australian and Pacific plates. Phase one of the Deep Fault Drilling Project (DFDP1) drilled two holes that sample the Alpine Fault zone (DFDP1A and DFDP1B) in the near surface. Two distinct principal slip zones (PSZ) were recovered in these cores (one in DFDP1A and two in DFDP1B) enabling investigation of chemical and mineralogical changes throughout the fault's hangingwall and footwall rocks. Here we use geochemical analyses to identify fault rock protoliths, alteration styles, and mass changes in the fault zone to test the control of chemical alteration on fault rock material properties and compare with distal parts of the fault zone sampled in the second phase of DFDP (DFDP2). 87Sr/86Sr and 143Nd/144Nd isotopes, and immobile trace element ratios identify protolith lithology contributions. We show that cataclasites above the upper principal slip zone in holes DFDP1A and DFDP1B contain a mixture of hangingwall Alpine Schist and radiogenic granitic and metasedimentary footwall lithologies indicating physical mixing of material up to ~25 m above the PSZ. In DFDP1B between upper and lower PSZs cataclasites distinctly resemble granitic footwall rocks, and below the lower PSZ radiogenic strontium isotope ratios identify porphyroclastic ultramylonite breccias as Australian plate Palaeozoic metasediments. Lithological mixing is overprinted by alteration of primary minerals to clays and infilling of pore spaces and fractures by calcite and chlorite. As proximity to the upper PSZ increases permeability decreases corresponding to an increase in volatile content (LOI). LOI peaks in the PSZ where permeability is lowest and clay content and carbonate cementation are greatest. Local, meteoric-derived spring waters are saturated in secondary minerals documented in the Alpine Fault zone and fault zone secondary mineral δD compositions indicate formation from meteoric waters

  14. Seasonal Snow Cold Content Dynamics in the Alpine and Sub-Alpine, Niwot Ridge, Colorado, USA

    NASA Astrophysics Data System (ADS)

    Jennings, K. S.; Molotch, N. P.

    2015-12-01

    Cold content represents the energy required to warm a sub-freezing snowpack to an isothermal 0°C. Across daily and seasonal time scales it is a dynamic interplay between the forces of snowpack accumulation/cooling and warming. Cold content determines snowmelt timing and is an important component of the annual energy budget of mountain sites with seasonal snowpacks. However, little is understood about seasonal snowpack cold content dynamics as calculating cold content requires depth-weighted snowpack temperature and snow water equivalent (SWE) measurements, which are scarce. A spatially distributed network of snow pits has been sampled since 1993 at the Niwot Ridge Long Term Ecological Research site on the eastern slope of the Continental Divide in Colorado's Front Range mountains. This study uses data from 3 pit sites that have at least 8 years of observations and represent alpine and sub-alpine environments. For these pits, cold content is strongly related to SWE during the cold content accumulation phase, here defined as December, January, and February. Average peak cold content ranges between -2.5 MJ m-2 and -9.2 MJ m-2 for the three sites and is strongly related to peak SWE. On average, cold content reaches its maximum on February 26, which is 61 days before the average date of peak SWE (i.e., the snowpack's cold content is satisfied over an average of 61 days). At the alpine site, later peak cold content and SWE was observed relative to the lower elevation sub-alpine sites. Interestingly, the alpine site had a smaller gap between peak cold content and SWE (55 days versus 67 days for the alpine and sub-alpine sites, respectively). The gap between peak cold content and peak SWE is primarily a function of the increase in SWE between the two dates. Hence, persistent snowfall after the date of peak cold content can delay the onset of snowmelt even if peak cold content was relatively low. Improving our understanding of seasonal cold content dynamics in mountain

  15. The Effectiveness of Cattlemans Detention Basin, South Lake Tahoe, California

    USGS Publications Warehouse

    Green, Jena M., (Edited By)

    2006-01-01

    Lake Tahoe (Nevada-California) has been designated as an 'outstanding national water resource' by the U.S. Environmental Protection Agency, in part, for its exceptional clarity. Water clarity in Lake Tahoe, however, has been declining at a rate of about one foot per year for more than 35 years. To decrease the amount of sediment and nutrients delivered to the lake by way of alpine streams, wetlands and stormwater detention basins have been installed at several locations around the lake. Although an improvement in stormwater and snowmelt runoff quality has been measured, the effectiveness of the detention basins for increasing the clarity of Lake Tahoe needs further study. It is possible that poor ground-water quality conditions exist beneath the detention basins and adjacent wetlands and that the presence of the basins has altered ground-water flow paths to nearby streams. A hydrogeochemical and ground-water flow modeling study was done at Cattlemans detention basin, situated adjacent to Cold Creek, a tributary to Lake Tahoe, to determine whether the focusing of storm and snowmelt runoff into a confined area has (1) modified the ground-water flow system beneath the detention basin and affected transport of sediment and nutrients to nearby streams and (2) provided an increased source of solutes which has changed the distribution of nutrients and affected nutrient transport rates beneath the basin. Results of slug tests and ground-water flow modeling suggest that ground water flows unrestricted northwest across the detention basin through the meadow. The modeling also indicates that seasonal flow patterns and flow direction remain similar from year to year under transient conditions. Model results imply that about 34 percent (0.004 ft3/s) of the total ground water within the model area originates from the detention basin. Of the 0.004 ft3/s, about 45 percent discharges to Cold Creek within the modeled area downstream of the detention basin. The remaining 55 percent

  16. Carbon sequestration in two alpine soils on the Tibetan Plateau.

    PubMed

    Tian, Yu-Qiang; Xu, Xing-Liang; Song, Ming-Hua; Zhou, Cai-Ping; Gao, Qiong; Ouyang, Hua

    2009-09-01

    Soil carbon sequestration was estimated in a conifer forest and an alpine meadow on the Tibetan Plateau using a carbon-14 radioactive label provided by thermonuclear weapon tests (known as bomb-(14)C). Soil organic matter was physically separated into light and heavy fractions. The concentration spike of bomb-(14)C occurred at a soil depth of 4 cm in both the forest soil and the alpine meadow soil. Based on the depth of the bomb-(14)C spike, the carbon sequestration rate was determined to be 38.5 g C/m(2) per year for the forest soil and 27.1 g C/m(2) per year for the alpine meadow soil. Considering that more than 60% of soil organic carbon (SOC) is stored in the heavy fraction and the large area of alpine forests and meadows on the Tibetan Plateau, these alpine ecosystems might partially contribute to "the missing carbon sink". PMID:19723249

  17. Characterizing streamflow generation in Alpine catchments

    NASA Astrophysics Data System (ADS)

    Chiogna, Gabriele; Cano Paoli, Karina; Bellin, Alberto

    2016-04-01

    Developing effective hydrological models for streamflow generation in Alpine catchments is challenging due to the inherent complexity of the intertwined processes controlling water transfer from hillslopes to streams and along the river network. With water discharge as the sole observational variable it is impossible to differentiate between different streamflow sources, and modelling activity is often limited to simplified phenomenological rainfall-runoff models. This study focuses on quantifying streamflow sources at different temporal scales and the associated uncertainty by using natural tracer data (electrical conductivity, oxygen and hydrogen stable isotopes ratios) as observational variables supplementing streamflow measurements. We determine the spatial and temporal hydrological behavior and the mean residence time of water in the Vermigliana catchment, North-Eastern Italy and we separate contributions to streamflow originating from Presena and Presanella glaciers, both exerting a strong control on the hydrologic budget of the study site. Furthermore, we identify a seasonal control on the effect of storm events. The catchment responded rapidly to precipitation events in early autumn, it was unaffected by precipitation events in early spring, while runoff generation was enhanced by snow melting in late autumn. Air temperature is identified as the main controlling parameter, in addition to precipitation. Two-component mixing analysis showed that the relative contribution of new water, which can contribute up to 75% of total streamflow, is very rapid. Only two hours time-lag was observed between the beginning of the precipitation event and the emergence of a significant contribution of new water. These results evidence the relevance of mixing between pre-event and event water in the Vermigliana catchment, and in similar high elevation Alpine catchments. This study provides new insights on the dynamics of streamflow generation in Alpine catchments and a

  18. 3D cartography of the Alpine Arc

    NASA Astrophysics Data System (ADS)

    Vouillamoz, N.; Sue, C.; Champagnac, J. D.; Calcagno, P.

    2012-04-01

    We present a 3D cartography of the alpine arc, a highly non-cylindrical mountain belt, built using the 3D GeoModeller of the BRGM (French geological survey). The model allows to handle the large-scale 3D structure of seventeen major crustal units of the belt (from the lower crust to the sedimentary cover nappes), and two main discontinuities (the Insubric line and the Crustal Penninic Front). It provides a unique document to better understand their structural relationships and to produce new sections. The study area comprises the western alpine arc, from the Jura to the Northwest, up to the Bergell granite intrusion and the Lepontine Dome to the East, and is limited to the South by the Ligurian basin. The model is limited vertically 10 km above sea level at the top, and the moho interface at the bottom. We discarded the structural relationships between the Alps sensus stricto and the surrounding geodynamic systems such as the Rhine graben or the connection with the Apennines. The 3D-model is based on the global integration of various data such as the DEM of the Alps, the moho isobaths, the simplified geological and tectonic maps of the belt, the crustal cross-sections ECORS-CROP and NFP-20, and complementary cross-sections specifically built to precise local complexities. The database has first been integrated in a GIS-project to prepare their implementation in the GeoModeller, by homogenizing the different spatial referencing systems. The global model is finally interpolated from all these data, using the potential field method. The final document is a new tri-dimentional cartography that would be used as input for further alpine studies.

  19. Is leg compression beneficial for alpine skiers?

    PubMed Central

    2013-01-01

    Background This study examined the effects of different levels of compression (0, 20 and 40 mmHg) produced by leg garments on selected psycho-physiological measures of performance while exposed to passive vibration (60 Hz, amplitude 4-6 mm) and performing 3-min of alpine skiing tuck position. Methods Prior to, during and following the experiment the electromygraphic (EMG) activity of different muscles, cardio-respiratory data, changes in total hemoglobin, tissue oxygenation and oscillatory movement of m. vastus lateralis, blood lactate and perceptual data of 12 highly trained alpine skiers were recorded. Maximal isometric knee extension and flexion strength, balance, and jumping performance were assessed before and after the experiment. Results The knee angle (−10°) and oscillatory movement (−20-25.5%) were lower with compression (P < 0.05 in all cases). The EMG activities of the tibialis anterior (20.2-28.9%), gastrocnemius medialis (4.9-15.1%), rectus femoris (9.6-23.5%), and vastus medialis (13.1-13.7%) muscles were all elevated by compression (P < 0.05 in all cases). Total hemoglobin was maintained during the 3-min period of simulated skiing with 20 or 40 mmHg compression, but the tissue saturation index was lower (P < 0.05) than with no compression. No differences in respiratory parameters, heart rate or blood lactate concentration were observed with or maximal isometric knee extension and flexion strength, balance, and jumping performance following simulated skiing for 3 min in the downhill tuck position were the same as in the absence of compression. Conclusions These findings demonstrate that with leg compression, alpine skiers could maintain a deeper tuck position with less perceived exertion and greater deoxygenation of the vastus lateralis muscle, with no differences in whole-body oxygen consumption or blood lactate concentration. These changes occurred without compromising maximal leg strength, jumping performance or balance

  20. Modelling vegetation dynamics for Alpine meadows

    NASA Astrophysics Data System (ADS)

    Della Chiesa, Stefano; Bertoldi, Giacomo; Wohlfahrt, Georg; Rist, Armin; Niedrist, Georg; Albertson, John D.; Tappeiner, Ulrike

    2010-05-01

    Regional climate scenarios predict a temperature increase and a summer precipitation decrease for the European Alps. This is expected to lead to longer vegetation periods, but also to drought stress in Alpine meadows ecosystems. It is therefore uncertain if the predicted climatic changes will lead to an increase or decrease of biomass production in these grassland ecosystems. Understanding plant growth requires to consider the complex interactions between soil, atmosphere and climate via its physiological properties, in particular LAI, stomatal resistance, rooting depth, albedo, surface roughness and effects on soil moisture. Vegetation Dynamic Models (VDM) coupled with hydrological models take into account these interactions in order to study and estimate biomass production quantitatively. In this contribution, the VDM previously developed by Montaldo et al. (2005) for semi-arid environments is extended to Alpine meadows in the Stubai Valley (Eastern Austria) which are typically not subjected to water and nutrient stresses, but undergoing low temperature limitations. The aim is to assess the model robustness. Moreover, the effects of mowing practice during the season were taken into consideration. The VDM has then been implemented in the distributed hydrological model GEOtop (Rigon et al., 2006). The VDM performed well in the considered case study. The validation and calibration of the model is presented and then the effects of increased temperature and decreased precipitation are investigated numerically. In order to evaluate in the field the effects of climatic change on Alpine grassland biomass production, the inner Alpine continental Mazia Valley (South Tyrol, Italy) has been chosen in 2009 for Long-Term Ecological Research. These climatic changes will be simulated by manipulations along an altitudinal gradient comprising measuring stations at about 1000 m, 1500 m and 2000 m a.s.l.. Meadow monoliths will be transplanted downslope to simulate temperature

  1. Lake Constance

    Atmospheric Science Data Center

    2013-04-17

    ... Swiss shores of Lake Constance at the town of Rorschach. Eutrophication, or the process of nutrient enrichment, is rapidly accelerated ... of the value of Lake Constance, efforts to mitigate eutrophication were initiated in the 1970's. MISR was built and is managed ...

  2. LAKE FORK

    EPA Science Inventory

    The Lake Fork of the Arkansas River Watershed has been adversely affected through mining, water diversion and storage projects, grazing, logging, and other human influences over the past 120 years. It is the goals of the LFWWG to improve the health of Lake fork by addressing th...

  3. High diversity of protistan plankton communities in remote high mountain lakes in the European Alps and the Himalayan mountains.

    PubMed

    Kammerlander, Barbara; Breiner, Hans-Werner; Filker, Sabine; Sommaruga, Ruben; Sonntag, Bettina; Stoeck, Thorsten

    2015-04-01

    We analyzed the genetic diversity (V4 region of the 18S rRNA) of planktonic microbial eukaryotes in four high mountain lakes including two remote biogeographic regions (the Himalayan mountains and the European Alps) and distinct habitat types (clear and glacier-fed turbid lakes). The recorded high genetic diversity in these lakes was far beyond of what is described from high mountain lake plankton. In total, we detected representatives from 66 families with the main taxon groups being Alveolata (55.0% OTUs 97%, operational taxonomic units), Stramenopiles (34.0% OTUs 97%), Cryptophyta (4.0% OTUs 97%), Chloroplastida (3.6% OTUs 97%) and Fungi (1.7% OTUs 97%). Centrohelida, Choanomonada, Rhizaria, Katablepharidae and Telonema were represented by <1% OTUs 97%. Himalayan lakes harbored a higher plankton diversity compared to the Alpine lakes (Shannon index). Community structures were significantly different between lake types and biogeographic regions (Fisher exact test, P < 0.01). Network analysis revealed that more families of the Chloroplastida (10 vs 5) and the Stramenopiles (14 vs 8) were found in the Himalayan lakes than in the Alpine lakes and none of the fungal families was shared between them. Biogeographic aspects as well as ecological factors such as water turbidity may structure the microbial eukaryote plankton communities in such remote lakes. PMID:25764458

  4. High diversity of protistan plankton communities in remote high mountain lakes in the European Alps and the Himalayan mountains

    PubMed Central

    Kammerlander, Barbara; Breiner, Hans-Werner; Filker, Sabine; Sommaruga, Ruben; Sonntag, Bettina; Stoeck, Thorsten

    2015-01-01

    We analyzed the genetic diversity (V4 region of the 18S rRNA) of planktonic microbial eukaryotes in four high mountain lakes including two remote biogeographic regions (the Himalayan mountains and the European Alps) and distinct habitat types (clear and glacier-fed turbid lakes). The recorded high genetic diversity in these lakes was far beyond of what is described from high mountain lake plankton. In total, we detected representatives from 66 families with the main taxon groups being Alveolata (55.0% OTUs97%, operational taxonomic units), Stramenopiles (34.0% OTUs97%), Cryptophyta (4.0% OTUs97%), Chloroplastida (3.6% OTUs97%) and Fungi (1.7% OTUs97%). Centrohelida, Choanomonada, Rhizaria, Katablepharidae and Telonema were represented by <1% OTUs97%. Himalayan lakes harbored a higher plankton diversity compared to the Alpine lakes (Shannon index). Community structures were significantly different between lake types and biogeographic regions (Fisher exact test, P < 0.01). Network analysis revealed that more families of the Chloroplastida (10 vs 5) and the Stramenopiles (14 vs 8) were found in the Himalayan lakes than in the Alpine lakes and none of the fungal families was shared between them. Biogeographic aspects as well as ecological factors such as water turbidity may structure the microbial eukaryote plankton communities in such remote lakes. PMID:25764458

  5. Simulation of Natural Acid Sulfate Weathering in an Alpine Watershed

    NASA Astrophysics Data System (ADS)

    Bassett, R. L.; Miller, William R.; McHugh, John; Catts, John G.

    1992-09-01

    Streams with acidic sulfate compositions (pH less than 3.5) are naturally generated in the alpine Geneva Creek Basin of the southern Rocky Mountains, an area underlain by Proterozoic metamorphic and igneous rocks that are intruded by Tertiary felsic stocks with associated pyritic alteration. These naturally acidic waters are similar in composition to more familiar man-made acid mine waters or to surface waters acidified by sulfate precipitation. Detailed study of the stream compositions has revealed the principal reactions driving the weathering process and was used to estimate the relative effects of snowpack ionic input versus the solute contribution from acid attack in soil zones and groundwater. In the Geneva Creek Basin, atmospheric sources of solute represent a minor component to the stream water composition, except for chloride, which can be used to determine the fraction of contribution. The weathering process is a balance between oxidation of sulfides, dissolution of silicates, formation of the clay minerals vermiculite, kaolinite, and smectite, carbonate neutralization, and precipitation of ferric and aluminum oxyhydroxides and aluminum sulfate. The chemical analyses of snow samples, multiple samples of water from Geneva Creek and its tributaries, and the composition of primary and secondary minerals identified in the basin serve as input to a mass balance geochemical model, which facilitates the interpretation of the principal geochemical processes.

  6. Metabolic Profiling of Alpine and Ecuadorian Lichens.

    PubMed

    Mittermeier, Verena K; Schmitt, Nicola; Volk, Lukas P M; Suárez, Juan Pablo; Beck, Andreas; Eisenreich, Wolfgang

    2015-01-01

    Non-targeted ¹H-NMR methods were used to determine metabolite profiles from crude extracts of Alpine and Ecuadorian lichens collected from their natural habitats. In control experiments, the robustness of metabolite detection and quantification was estimated using replicate measurements of Stereocaulon alpinum extracts. The deviations in the overall metabolite fingerprints were low when analyzing S. alpinum collections from different locations or during different annual and seasonal periods. In contrast, metabolite profiles observed from extracts of different Alpine and Ecuadorian lichens clearly revealed genus- and species-specific profiles. The discriminating functions determining cluster formation in principle component analysis (PCA) were due to differences in the amounts of genus-specific compounds such as sticticin from the Sticta species, but also in the amounts of ubiquitous metabolites, such as sugar alcohols or trehalose. However, varying concentrations of these metabolites from the same lichen species e.g., due to different environmental conditions appeared of minor relevance for the overall cluster formation in PCA. The metabolic clusters matched phylogenetic analyses using nuclear ribosomal DNA (nrDNA) internal transcribed spacer (ITS) sequences of lichen mycobionts, as exemplified for the genus Sticta. It can be concluded that NMR-based non-targeted metabolic profiling is a useful tool in the chemo-taxonomy of lichens. The same approach could also facilitate the discovery of novel lichen metabolites on a rapid and systematical basis. PMID:26437395

  7. Resource partitioning in two heterochronic populations of Greek Alpine newts, Triturus alpestris veluchiensis

    NASA Astrophysics Data System (ADS)

    Denoël, Mathieu; Schabetsberger, Robert

    2003-04-01

    Current ecological models suggest that the maintenance of trophic polymorphisms is favoured by a different resource use in alternative morphs. Facultative paedomorphosis in newts is an example of phenotypic variation as paedomorphs retain morphological larval traits, such as gills and gill slits. The aim of this study was to find out whether heterochronic morphs occupy particular micro-habitats and focus on specific prey items. Resource partitioning was found between morphs. It concerns mainly food selection with paedomorphs preying more on plankton and less on terrestrial invertebrates than metamorphs. Some habitat specializations were also found with metamorphs being more abundant at the water surface than paedomorphs. Diel variation in habitat use of the two different morphs was minimal. Polymorphism allows Alpine newts to exploit the different resources in the lakes in order to minimize intraspecific competition, but the extent of resource partitioning depends on habitat characteristics.

  8. Effects of acid precipitation on reproduction in alpine plant species. [Erythronium grandiflorum; Aquilegia caerulea

    SciTech Connect

    McKenna, M.A.; Hille-Salgueiro, M.; Musselman, R.C. Dept. of Agriculture, Fort Collins, CO )

    1990-01-01

    A series of experiments were designed to determine the impact of acid rain on plant reproductive processes, a critical component of a species life history. Research was carried out in herbaceous alpine communities at the USDA (United States Department of Agriculture) Forest Service Glacier Lakes Ecosystem Experiments Site in the Snowy Mts. of Wyoming. A range of species were surveyed to monitor the sensitivity of pollen to acidification during germination and growth, and all species demonstrated reduced in vitro pollen germination in acidified media. Field pollinations were carried out in Erythronium grandiflorum and Aquilegia caerulea to determine the reproductive success of plants exposed to simulated ambient precipitation (pH 5.6) or simulated acid precipitation (pH 3.6) prior to pollination. In Erythronium, no differences were observed in seed set and seed weight of fruits resulting from the two pollination treatments. In Aquilegia, fruits resulting from the acid spray treatment produced fewer seeds and lighter seeds.

  9. Conifer density within lake catchments predicts fish mercury concentrations in remote subalpine lakes.

    PubMed

    Eagles-Smith, Collin A; Herring, Garth; Johnson, Branden; Graw, Rick

    2016-05-01

    Remote high-elevation lakes represent unique environments for evaluating the bioaccumulation of atmospherically deposited mercury through freshwater food webs, as well as for evaluating the relative importance of mercury loading versus landscape influences on mercury bioaccumulation. The increase in mercury deposition to these systems over the past century, coupled with their limited exposure to direct anthropogenic disturbance make them useful indicators for estimating how changes in mercury emissions may propagate to changes in Hg bioaccumulation and ecological risk. We evaluated mercury concentrations in resident fish from 28 high-elevation, sub-alpine lakes in the Pacific Northwest region of the United States. Fish total mercury (THg) concentrations ranged from 4 to 438 ng/g wet weight, with a geometric mean concentration (±standard error) of 43 ± 2 ng/g ww. Fish THg concentrations were negatively correlated with relative condition factor, indicating that faster growing fish that are in better condition have lower THg concentrations. Across the 28 study lakes, mean THg concentrations of resident salmonid fishes varied as much as 18-fold among lakes. We used a hierarchal statistical approach to evaluate the relative importance of physiological, limnological, and catchment drivers of fish Hg concentrations. Our top statistical model explained 87% of the variability in fish THg concentrations among lakes with four key landscape and limnological variables: catchment conifer density (basal area of conifers within a lake's catchment), lake surface area, aqueous dissolved sulfate, and dissolved organic carbon. Conifer density within a lake's catchment was the most important variable explaining fish THg concentrations across lakes, with THg concentrations differing by more than 400 percent across the forest density spectrum. These results illustrate the importance of landscape characteristics in controlling mercury bioaccumulation in fish. PMID:26854697

  10. Conifer density within lake catchments predicts fish mercury concentrations in remote subalpine lakes

    USGS Publications Warehouse

    Eagles-Smith, Collin A.; Herring, Garth; Johnson, Branden L.; Graw, Rick

    2016-01-01

    Remote high-elevation lakes represent unique environments for evaluating the bioaccumulation of atmospherically deposited mercury through freshwater food webs, as well as for evaluating the relative importance of mercury loading versus landscape influences on mercury bioaccumulation. The increase in mercury deposition to these systems over the past century, coupled with their limited exposure to direct anthropogenic disturbance make them useful indicators for estimating how changes in mercury emissions may propagate to changes in Hg bioaccumulation and ecological risk. We evaluated mercury concentrations in resident fish from 28 high-elevation, sub-alpine lakes in the Pacific Northwest region of the United States. Fish total mercury (THg) concentrations ranged from 4 to 438 ng/g wet weight, with a geometric mean concentration (±standard error) of 43 ± 2 ng/g ww. Fish THg concentrations were negatively correlated with relative condition factor, indicating that faster growing fish that are in better condition have lower THg concentrations. Across the 28 study lakes, mean THg concentrations of resident salmonid fishes varied as much as 18-fold among lakes. We used a hierarchal statistical approach to evaluate the relative importance of physiological, limnological, and catchment drivers of fish Hg concentrations. Our top statistical model explained 87% of the variability in fish THg concentrations among lakes with four key landscape and limnological variables: catchment conifer density (basal area of conifers within a lake's catchment), lake surface area, aqueous dissolved sulfate, and dissolved organic carbon. Conifer density within a lake's catchment was the most important variable explaining fish THg concentrations across lakes, with THg concentrations differing by more than 400 percent across the forest density spectrum. These results illustrate the importance of landscape characteristics in controlling mercury bioaccumulation in fish.

  11. Changes in Quadriceps Muscle Activity During Sustained Recreational Alpine Skiing

    PubMed Central

    Kröll, Josef; Müller, Erich; Seifert, John G.; Wakeling, James M.

    2011-01-01

    During a day of skiing thousands of repeated contractions take place. Previous research on prolonged recreational alpine skiing show that physiological changes occur and hence some level of fatigue is inevitable. In the present paper the effect of prolonged skiing on the recruitment and coordination of the muscle activity was investigated. Six subjects performed 24 standardized runs. Muscle activity during the first two (PREskiing) and the last two (POSTskiing) runs was measured from the vastus lateralis (VL) and rectus femoris (RF) using EMG and quantified using wavelet and principal component analysis. The frequency content of the EMG signal shifted in seven out of eight cases significantly towards lower frequencies with highest effects observed for RF on outside leg. A significant pronounced outside leg loading occurred during POSTskiing and the timing of muscle activity peaks occurred more towards turn completion. Specific EMG frequency changes were observed at certain time points throughout the time windows and not over the whole double turn. It is suggested that general muscular fatigue, where additional specific muscle fibers have to be recruited due to the reduced power output of other fibers did not occur. The EMG frequency decrease and intensity changes for RF and VL are caused by altered timing (coordination) within the turn towards a most likely more uncontrolled skiing technique. Hence, these data provide evidence to suggest recreational skiers alter their skiing technique before a potential change in muscle fiber recruitment occurs. Key points The frequency content of the EMG signal shifted in seven out of eight cases significantly towards lower frequencies with highest effects observed for RF. General muscular fatigue, where additional specific fibers have to be recruited due to the reduced power output of other fibers, did not occur. A modified skiing style towards a less functional and hence more uncontrolled skiing technique seems to be a key

  12. Organic matter controls of soil water retention in an alpine grassland and its significance for hydrological processes

    NASA Astrophysics Data System (ADS)

    Yang, Fei; Zhang, Gan-Lin; Yang, Jin-Ling; Li, De-Cheng; Zhao, Yu-Guo; Liu, Feng; Yang, Ren-Min; Yang, Fan

    2014-11-01

    Soil water retention influences many soil properties and soil hydrological processes. The alpine meadows and steppes of the Qilian Mountains on the northeast border of the Qinghai-Tibetan Plateau form the source area of the Heihe River, the second largest inland river in China. The soils of this area therefore have a large effect on water movement and storage of the entire watershed. In order to understand the controlling factors of soil water retention and how they affect regional eco-hydrological processes in an alpine grassland, thirty-five pedogenic horizons in fourteen soil profiles along two facing hillslopes in typical watersheds of this area were selected for study. Results show that the extensively-accumulated soil organic matter plays a dominant role in controlling soil water retention in this alpine environment. We distinguished two mechanisms of this control. First, at high matric potentials soil organic matter affected soil water retention mainly through altering soil structural parameters and thereby soil bulk density. Second, at low matric potentials the water adsorbing capacity of soil organic matter directly affected water retention. To investigate the hydrological functions of soils at larger scales, soil water retention was compared by three generalized pedogenic horizons. Among these soil horizons, the mattic A horizon, a diagnostic surface horizon of Chinese Soil Taxonomy defined specially for alpine meadow soils, had the greatest soil water retention over the entire range of measured matric potentials. Hillslopes with soils having these horizons are expected to have low surface runoff. This study promotes the understanding of the critical role of alpine soils, especially the vegetated surface soils in controlling the eco-hydrological processes in source regions of the Heihe River watershed.

  13. Lake Tapps tephra: An early Pleistocene stratigraphic marker in the Puget Lowland, Washington

    USGS Publications Warehouse

    Westgate, J.A.; Easterbrook, D.J.; Naeser, N.D.; Carson, R.J.

    1987-01-01

    The rhyolitic Lake Tapps tephra was deposited about 1.0 myr ago, shortly after culmination of the early phase of the Salmon Springs Glaciation in the Puget Lowland. It is contained within sediments that were deposited in ponds or lakes in front of the reteating glacier. An herb-dominated tundra existed in the southern Puget Lowland at that time. Lake Tapps tephra is most likely the product of an eruption that in part was phreatomagmatic. It forms an early Pleistocene stratigraphic marker across the southern sector of the Puget Lowland and provides a link between Puget lobe sediments of the Cordilleran Ice Sheet and sediments deposited by Olympic alpine glaciers. ?? 1987.

  14. Pleistocene origin and population history of a neoendemic alpine butterfly.

    PubMed

    Schoville, Sean D; Stuckey, Matthew; Roderick, George K

    2011-03-01

    Alpine environments underwent dramatic transformation during glacial-interglacial cycles, with the consequence that geographical, ecological and demographic changes of alpine populations provided the opportunity for formation of neoendemic species. Several biogeographical models have been proposed to account for the unique history of alpine populations, with different expectations of genetic divergence and speciation. The expanding alpine archipelago model proposes that alpine populations expand spatially and demographically during glacial events, dispersing between mountain ranges. Under this model, alpine populations are unlikely to diverge in isolation due to substantial interpopulation gene flow. In contrast, the alpine archipelago refuge model proposes that gene flow during glacial phases is limited and populations expand demographically during interglacial phases, increasing genetic isolation and the likelihood of speciation. We assess these models by reconstructing the evolutionary history of Colias behrii, a morphologically and ecologically distinct alpine butterfly restricted to the California Sierra Nevada. C. behrii exhibits very low genetic diversity at mitochondrial and nuclear loci, limited population structure and evidence of population expansion. C. behrii and Rocky Mountain C. meadii share identical mitochondrial haplotypes, while in contrast, nuclear data indicate common ancestry between C. behrii and Cascades Range Colias pelidne. The conflict in gene genealogies may be a result of recent expansion in North American Colias, but an isolation with migration analysis indicates that genetic patterns in C. behrii might result from differential introgression following hybridization. Based on the timing of population expansion and gene flow between mountain ranges, the expanding alpine archipelago model is supported in C. behrii. PMID:21244539

  15. Interaction of various flow systems in small alpine catchments: conceptual model of the upper Gurk Valley aquifer, Carinthia, Austria

    NASA Astrophysics Data System (ADS)

    Hilberg, Sylke; Riepler, Franz

    2016-03-01

    Small alpine valleys usually show a heterogeneous hydraulic situation. Recurring landslides create temporal barriers for the surface runoff. As a result of these postglacial processes, temporal lakes form, and thus lacustrine fine-grained sedimentation intercalates with alluvial coarse-grained layers. A sequence of alluvial sediments (confined and thus well protected aquifers) and lacustrine sediments (aquitards) is characteristic for such an environment. The hydrogeological situation of fractured hard-rock aquifers in the framing mountain ranges is characterized by superficially high hydraulic conductivities as the result of tectonic processes, deglaciation and postglacial weathering. Fracture permeability and high hydraulic gradients in small-scaled alpine catchments result in the interaction of various flow systems in various kinds of aquifers. Spatial restrictions and conflicts between the current land use and the requirements of drinking-water protection represent a special challenge for water resource management in usually densely populated small alpine valleys. The presented case study describes hydrogeological investigations within the small alpine valley of the upper Gurktal (Upper Carinthia, Austria) and the adjacent Höllenberg Massif (1,772 m above sea level). Hydrogeological mapping, drilling, and hydrochemical and stable isotope analyses of springs and groundwater were conducted to identify a sustainable drinking-water supply for approximately 1,500 inhabitants. The results contribute to a conceptual hydrogeological model with three interacting flow systems. The local and the intermediate flow systems are assigned to the catchment of the Höllenberg Massif, whereas the regional flow system refers to the bordering Gurktal Alps to the north and provides an appropriate drinking water reservoir.

  16. Interaction of various flow systems in small alpine catchments: conceptual model of the upper Gurk Valley aquifer, Carinthia, Austria

    NASA Astrophysics Data System (ADS)

    Hilberg, Sylke; Riepler, Franz

    2016-08-01

    Small alpine valleys usually show a heterogeneous hydraulic situation. Recurring landslides create temporal barriers for the surface runoff. As a result of these postglacial processes, temporal lakes form, and thus lacustrine fine-grained sedimentation intercalates with alluvial coarse-grained layers. A sequence of alluvial sediments (confined and thus well protected aquifers) and lacustrine sediments (aquitards) is characteristic for such an environment. The hydrogeological situation of fractured hard-rock aquifers in the framing mountain ranges is characterized by superficially high hydraulic conductivities as the result of tectonic processes, deglaciation and postglacial weathering. Fracture permeability and high hydraulic gradients in small-scaled alpine catchments result in the interaction of various flow systems in various kinds of aquifers. Spatial restrictions and conflicts between the current land use and the requirements of drinking-water protection represent a special challenge for water resource management in usually densely populated small alpine valleys. The presented case study describes hydrogeological investigations within the small alpine valley of the upper Gurktal (Upper Carinthia, Austria) and the adjacent Höllenberg Massif (1,772 m above sea level). Hydrogeological mapping, drilling, and hydrochemical and stable isotope analyses of springs and groundwater were conducted to identify a sustainable drinking-water supply for approximately 1,500 inhabitants. The results contribute to a conceptual hydrogeological model with three interacting flow systems. The local and the intermediate flow systems are assigned to the catchment of the Höllenberg Massif, whereas the regional flow system refers to the bordering Gurktal Alps to the north and provides an appropriate drinking water reservoir.

  17. Quantified sensitivity of lakes to record historic earthquakes: Implications for paleoseismology

    NASA Astrophysics Data System (ADS)

    Wilhelm, Bruno; Nomade, Jerome; Crouzet, Christian; Litty, Camille; Belle, Simon; Rolland, Yann; Revel, Marie; Courboulex, Françoise; Arnaud, Fabien; Anselmetti, Flavio S.

    2015-04-01

    Seismic hazard assessment is a challenging issue for modern societies. A key parameter to be estimated is the recurrence interval of damaging earthquakes. In moderately active seismo-tectonic regions, this requires the establishment of earthquake records long enough to be relevant, i.e. far longer than historical observations. Here we investigate how lake sediments can be used for this purpose and quantify the conditions that enable earthquake recording. For this purpose, (i) we studied nine lake-sediment sequences to reconstruct mass-movement chronicles in different settings of the French Alpine range and (ii) we compared the chronicles to the well-documented earthquake history over the last five centuries. The studied lakes are all small alpine-type lakes based directly on bedrock. All lake sequences have been studied following the same methodology; (i) a multi-core approach to well understand the sedimentary processes within the lake basins, (ii) a high-resolution lithological and grain-size characterization and (iii) a dating based on short-lived radionuclide measurements, lead contaminations and radiocarbon ages. We identified 40 deposits related to 26 mass-movement (MM) occurrences. 46% (12 on 26) of the MMs are synchronous in neighbouring lakes, supporting strongly an earthquake origin. In addition, the good agreement between MMs ages and historical earthquake dates suggests an earthquake trigger for 88% (23 on 26) of them. Related epicenters are always located at distances of less than 100 km from the lakes and their epicentral MSK intensity ranges between VII and IX. However, the number of earthquake-triggered MMs varies between lakes of a same region, suggesting a gradual sensitivity of the lake sequences towards earthquake shaking, i.e. distinct lake-sediment slope stabilities. The quantification of this earthquake sensitivity and the comparison to the lake system and sediment characteristics suggest that the primary factor explaining this variability is

  18. Precipitation overrides warming in mediating soil nitrogen pools in an alpine grassland ecosystem on the Tibetan Plateau

    PubMed Central

    Lin, Li; Zhu, Biao; Chen, Chengrong; Zhang, Zhenhua; Wang, Qi-Bing; He, Jin-Sheng

    2016-01-01

    Soils in the alpine grassland store a large amount of nitrogen (N) due to slow decomposition. However, the decomposition could be affected by climate change, which has profound impacts on soil N cycling. We investigated the changes of soil total N and five labile N stocks in the topsoil, the subsoil and the entire soil profile in response to three years of experimental warming and altered precipitation in a Tibetan alpine grassland. We found that warming significantly increased soil nitrate N stock and decreased microbial biomass N (MBN) stock. Increased precipitation reduced nitrate N, dissolved organic N and amino acid N stocks, but increased MBN stock in the topsoil. No change in soil total N was detected under warming and altered precipitation regimes. Redundancy analysis further revealed that soil moisture (26.3%) overrode soil temperature (10.4%) in explaining the variations of soil N stocks across the treatments. Our results suggest that precipitation exerted stronger influence than warming on soil N pools in this mesic and high-elevation grassland ecosystem. This indicates that the projected rise in future precipitation may lead to a significant loss of dissolved soil N pools by stimulating the biogeochemical processes in this alpine grassland. PMID:27527683

  19. Precipitation overrides warming in mediating soil nitrogen pools in an alpine grassland ecosystem on the Tibetan Plateau.

    PubMed

    Lin, Li; Zhu, Biao; Chen, Chengrong; Zhang, Zhenhua; Wang, Qi-Bing; He, Jin-Sheng

    2016-01-01

    Soils in the alpine grassland store a large amount of nitrogen (N) due to slow decomposition. However, the decomposition could be affected by climate change, which has profound impacts on soil N cycling. We investigated the changes of soil total N and five labile N stocks in the topsoil, the subsoil and the entire soil profile in response to three years of experimental warming and altered precipitation in a Tibetan alpine grassland. We found that warming significantly increased soil nitrate N stock and decreased microbial biomass N (MBN) stock. Increased precipitation reduced nitrate N, dissolved organic N and amino acid N stocks, but increased MBN stock in the topsoil. No change in soil total N was detected under warming and altered precipitation regimes. Redundancy analysis further revealed that soil moisture (26.3%) overrode soil temperature (10.4%) in explaining the variations of soil N stocks across the treatments. Our results suggest that precipitation exerted stronger influence than warming on soil N pools in this mesic and high-elevation grassland ecosystem. This indicates that the projected rise in future precipitation may lead to a significant loss of dissolved soil N pools by stimulating the biogeochemical processes in this alpine grassland. PMID:27527683

  20. Eutrophication of Typical Chinese Shallow Lakes as affected by Hydrologic Characteristics and Lake-Basin Morphology

    NASA Astrophysics Data System (ADS)

    Huang, J.; Xu, Q.; Xi, B.; Wang, X.; Li, W.; Ji, D.; Jiang, T.

    2013-12-01

    The region below midstream of the Yangtze River is one of the areas in China that have a highest density of lakes, in particular shallow lakes. It has five nationally well-known freshwater lakes with largest sizes, namely the Poyang Lake, Doingting Lake, Taihu Lake, Chaohu Lake, and Hongze Lake. This region has 138 lakes with a water surface area of 10 km2 or larger. However, approximately 70% of the large- to medium-sized lakes in the eastern plains of China have been altered from pristine into reservoir-like conditions. Previous studies indicate that hydrologic characteristics and lake-basin morphology likely have important effects on the water quality (or eutrophication) of shallow lakes. However, little is known about quantitative relations among lake water quality, lake-basin morphology, and hydrologic characteristics. The objective of this study was to determine such quantitative relations using data on water quality, water ecology, hydrology, and basin morphology. The data were collected from 2008 to 2011 for ninety shallow lakes in the eastern plains of China. The results indicate that total nitrogen (TN), total phosphorus (TP), chlorophyll-a (Chl-a) concentrations decreased with increase of water depth. TN and TP concentrations in the lakes with a water depth of greater than 2m were less than those in the lakes with a water depth less than 2m. In addition, Chl-a concentration in the lakes with a surface area less than 25 km2 increased with the increase of relative water depth (Zr), whereas Chl-a concentration in the lakes with a surface area greater than 25 km2 decreased with the increase of Zr. Further, as influenced by hydrologic characteristics, the lakes in the upper reaches of the Yangtze River tended to have a better water quality than the lakes in the lower reaches, while the lakes that are hydraulically connected with the Yangtze River tended to have a better water quality than the lakes that are hydraulically disconnected from the river.

  1. Neotectonic fault structures in the Lake Thun area (Switzerland)

    NASA Astrophysics Data System (ADS)

    Fabbri, Stefano C.; Herwegh, Marco; Schlunegger, Fritz; Hübscher, Christian; Weiss, Benedikt J.; Schmelzbach, Cédric; Horstmeyer, Heinrich; Merz, Kaspar; Anselmetti, Flavio S.

    2016-04-01

    Strong historic earthquakes (i.e. intensities I0 ≥ V) in Switzerland are well documented by the earthquake catalogue of Switzerland ECOS-09 (e.g. Frutigen, 1729 AD, Mw=5.2, I0=VI). Many of these strong events can be recognized paleoseismically by large subaquatic, earthquake-triggered mass movements that occur frequently in Swiss Lakes. Some of these represent the occasional occurrence of even stronger earthquakes (i.e. Mw ˜6.5) in the Alpine region (Strasser et al., 2013), which are expected to produce noticeable surface ruptures. However, convincing evidence for Quaternary displacements with offset surface expressions have scarcely been found (e.g., Wiemer et al., 2009). Applying a multi-disciplinary approach, this study presents potential candidates for such faults in the larger Lake Thun area at the edge of the Alps. The overdeepened basin of Lake Thun is situated at the northern Alpine front, which extends orthogonally to the general strike direction of the Alpine nappe front. The northern shoreline is predominantly shaped by the front of the Subalpine Molasse, which is in strong contrast to the south western shore built by the structurally higher units of the Middle and Lower Penninic nappes. This pattern with obvious differences of both lake sides suggests a major fault along the lake axis and high tectonic activity during nappe emplacement, i.e. from Eocene times throughout the Late Miocene. The area is dominated today by a strike-slip stress regime with a slight normal faulting component (Kastrup et al., 2004). As part of a multi-disciplinary study, attempting to find potential neotectonically active fault structures in the Lake Thun area, a 2D ground penetrating radar (GPR) survey was conducted. The aim of the GPR survey was to link observations from a multichannel reflection seismic survey and a multibeam bathymetric survey carried out in Lake Thun with findings in a nearby gravel quarry revealing suspicious deformation features such as rotated gravel

  2. The Eastern Alpine Seismic Investigation (EASI) project

    NASA Astrophysics Data System (ADS)

    Plomerova, Jaroslava; Bianchi, Irene; Hetényi, György; Munzarova, Helena; Bokelmann, Götz; Kissling, Edi; AlpArray-EASI Working Group; AlpArray-EASI Field Team

    2015-04-01

    AlpArray (http://www.seismo.ethz.ch/research/groups/alrt/projects/alparray/) is a large European initiative to study the entire Alpine orogen at high resolution and in 3D with a large variety of methods. The core element of the initiative is an extensive and dense broadband seismological network. In addition, a number of Complementary Experiments will be conducted to focus on targeted problems. The first implemented AlpArray Complementary Experiment is called Eastern Alpine Seismic Investigation (EASI). The Eastern, "straight" part of the Alps is home to a number of open questions, e.g., the origin of the hanging lithospheric slab (Adriatic or European?), the nature of the Moho "hole" between the two plates, the anisotropic nature of the lower crust, and the relationship of the Alpine orogen to the adjacent foreland basin and the lithospheric blocks of the Bohemian Massif. Our research methods include tomography, ambient noise analysis and receiver functions, with anisotropy included in all three types of investigations as well as in shear-wave splitting analyses. The depth range of investigations encompasses the crust and the mantle lithosphere, down to the LAB. In this presentation we detail the design of the experiment. EASI is composed of 55 broadband seismic stations, deployed in a zig-zag pattern on either side of the central longitude line of 13.35°E. The planned north-south distance between stations was 10 km, the distance of each station to either side of the central line was 6 km. We aimed to keep the stations within 1.5 km of the target location, as much as topographic, field and infrastructure condition allowed. The result: with respect to the original deployment plans the closest match is 164m, 10 stations are within 500m, 31 stations are within 1.5km which is also the average match, and the farthest is 4.4km. The overall result remained a very linear and regularly spaced array, spanning 540 km from the Czech-German border to the Adriatic Sea. The

  3. CHARACTERIZATION OF ENDOCRINE-DISRUPTION AND CLINICAL MANIFESTATIONS IN LARGE-MOUTH BASS FROM FLORIDA LAKES

    EPA Science Inventory

    Previous efforts from this laboratory, have documented altered endocrine function and sexual differentiation for alligators and turtles from Lake Apopka in Central Florida. This lake has been exposed to a variety of contaminants which are potentially endocrine-disrupting. Therefo...

  4. Sustainable use of alpine and pre-alpine grassland soils in a changing climate (SUSALPS)

    NASA Astrophysics Data System (ADS)

    Zistl-Schlingmann, Marcus; Beck, Robert; Brandhuber, Robert; Butterbach-Bahl, Klaus; Garcia Franco, Noelia; von Gillhaußen, Phillip; Jentsch, Anke; Kiese, Ralf; Krämer, Alexander; Kögel-Knabner, Ingrid; Köllner, Thomas; Poppenborg, Patrick; Schloter, Michael; Schulz, Stefanie; Wiesmeier, Martin; Wolf, Benjamin; Dannenmann, Michael

    2016-04-01

    The development of ecologically as well as economically sustainable management options for the carbon- and nitrogen rich alpine and pre-alpine grassland soils in a changing climate poses a grand scientific and socio- economical challenge. The transdisciplinary SUSALPS project starting in 2016 aims to essentially improve the knowledge on the functionality of alpine and pre-alpine grassland soils using both natural-scientific/ technical and socio economical approaches. The project is building on existing infrastructure of German grassland-ecosystem-research like the pre-alpine TERENO (Terrestrial ecosystem observation network observatory) observatory sites, the EVENT and SIGNAL sites as well as long term LfL (Bayerische Landesanstalt für Landwirtschaft) sites, plus a new additional high elevation (1400m a.s.l) site in the Bavarian Alps. The site setup along the elevational gradient on the edge of the Alps (1400 m to 300 m) is used for space-for-time climate change experiments which are combined with extensive and intensive management treatments. A key focus of SUSALPS will be the characterization of combined climate change/management effects on carbon and nitrogen biogeochemistry. Hence, we will evaluate the influence of different management options and current and future climate changes on the soil microbiome and associated biogeochemical processes in the plant-soil-system, on nitrogen use efficiency, on biosphere-atmosphere exchange of greenhouse gases as well as on leaching of environmentally relevant compounds. For this purpose, we simulate the predicted climate change in the region by translocation of large lysimeters (1m2, 1.4m depth; TERENO lysimeters, translocated in 2011) for measurements of biosphere-atmosphere hydrosphere exchange of environmentally relevant C and N compounds as well as by newly transferred smaller plant-soil-mesocosms used for destructive biogeochemical process studies. By closely linking this experimental work with biogeochemical and

  5. Seismic monitoring of an Alpine mountain river

    NASA Astrophysics Data System (ADS)

    Díaz, J.; Ruíz, M.; Crescentini, L.; Amoruso, A.; Gallart, J.

    2014-04-01

    The Canfranc underground laboratory (LSC), excavated under the Central Pyrenees, is mainly devoted to the study of phenomena which needs "cosmic silence." It also hosts a geodynamical facility, named Geodyn, which holds an accelerometer, a broadband seismometer, and two high-resolution laser strainmeters. During the routine processing of the seismic data, we detected an unusual spectral signature in the 2-10 Hz frequency band, which does not correspond to the typical sources of seismic noise and which can also be recognized in the strain records. After checking against meteorological and hydrological data, we can relate those signals to variations in the discharge by the Aragon River, an Alpine-style river in the southern Pyrenees, located about 400 m from the LSC Geodyn facility. Four main episodes have been identified since early 2011, each lasting 1-2 to 6-8 days. Additionally, a limited number of shorter episodes have also been detected. Three types of river-generated seismic events have been identified, related respectively to moderate rainfall, snowmelt, and flooding events associated to severe storms. Each of those types has distinctive characteristics which allow monitoring the hydrological events from the analysis of seismic and deformation data. A few previous studies have already described the seismic noise close to rivers with larger discharge or in small-scale experimental settings, and we are showing here that the so-called "fluvial seismology" can be useful to study the hydrological evolution of Alpine style streams and may have a potential interest for the civil authorities in charge of the management of hydrological basins.

  6. Arctic and Alpine Vegetations: Similarities, Differences, and Susceptibility to Disturbance

    ERIC Educational Resources Information Center

    Billings, W. D.

    1973-01-01

    Discusses environmental and biological aspects of arctic and alpine vegetations in the New World between the equator and the Arctic Ocean, considering their similarities, differences, and susceptibility to disturbance by man. (JR)

  7. A satellite-based climatology (1989-2012) of lake surface water temperature from AVHRR 1-km for Central European water bodies

    NASA Astrophysics Data System (ADS)

    Riffler, Michael; Wunderle, Stefan

    2013-04-01

    The temperature of lakes is an important parameter for lake ecosystems influencing the speed of physio-chemical reactions, the concentration of dissolved gazes (e.g. oxygen), and vertical mixing. Even small temperature changes might have irreversible effects on the lacustrine system due to the high specific heat capacity of water. These effects could alter the quality of lake water depending on parameters like lake size and volume. Numerous studies mention lake water temperature as an indicator of climate change and in the Global Climate Observing System (GCOS) requirements it is listed as an essential climate variable. In contrast to in situ observations, satellite imagery offers the possibility to derive spatial patterns of lake surface water temperature (LSWT) and their variability. Moreover, although for some European lakes long in situ time series are available, the temperatures of many lakes are not measured or only on a non-regular basis making these observations insufficient for climate monitoring. However, only few satellite sensors offer the possibility to analyze time series which cover more than 20 years. The Advanced Very High Resolution Radiometer (AVHRR) is among these and has been flown on the National Oceanic and Atmospheric Administration (NOAA) Polar Operational Environmental Satellites (POES) and on the Meteorological Operational Satellites (MetOp) from the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) as a heritage instrument for almost 35 years. It will be carried on for at least ten more years finally offering a unique opportunity for satellite-based climate studies. Herein we present the results from a study initiated by the Swiss GCOS office to generate a satellite-based LSWT climatology for the pre-alpine water bodies in Switzerland. It relies on the extensive AVHRR 1-km data record (1985-2012) of the Remote Sensing Research Group at the University of Bern (RSGB) and has been derived from the AVHRR/2

  8. The onset of alpine pastoral systems in the Eastern Alps

    NASA Astrophysics Data System (ADS)

    Oeggl, Klaus; Festi, Daniela; Putzer, Andreas

    2015-04-01

    Since the discovery of the Neolithic glacier mummy "Ötzi" in the nival belt of the main Alpine ridge, the onset of alpine pasture is matter of a highly controversial debate both in archaeology and in palaeo-ecology of the Eastern Alps. The implication is that his sojourn in the high-altitudes of the Alps is considered to be connected with pastoral nomadism. Regrettably any archaeological evidence for the existence of such Neolithic alpine pastoral systems is missing up to now and the assumption is based on palynological data only. However, also the palynological record is ambiguous, because pasture indicators in the alpine regions react positive on grazing as well as on fertilization induced by a higher runoff of precipitation. Thus alpine pasture indicators reflect both grazing pressure and climatic change. Anyhow, alpine pastoral systems are a common practice in Alpine animal husbandry, but from an economic point of view such a seasonal vertical transhumance is costly. There are three main reasons for its practice: i) climatic, ii) economic (mainly in connection with population pressure or mining activities), and iii) cultural ideology. In this study we tested the above mentioned reasons in an interdisciplinary study on the beginning of pastoral activities in high altitudes in the central part of the Eastern Alps. This is conducted by palynological analyses of peat deposits situated in the vicinity of the timberline (1600 - 2400 m a.s.l.) combined with archaeological surveys. The investigated sites are located in traditional Alpine transhumance regions and aligned on a transect through the central part of the Eastern Alps. The studies reveal that grazing pressure is reflected since the Bronze Age, which is corroborated by archaeological findings in the vicinity of the investigated sites.

  9. Sensitivity of Alpine Snow and Streamflow Regimes to Climate Changes

    NASA Astrophysics Data System (ADS)

    Rasouli, K.; Pomeroy, J. W.; Marks, D. G.; Bernhardt, M.

    2014-12-01

    Understanding the sensitivity of hydrological processes to climate change in alpine areas with snow dominated regimes is of paramount importance as alpine basins show both high runoff efficiency associated with the melt of the seasonal snowpack and great sensitivity of snow processes to temperature change. In this study, meteorological data measured in a selection of alpine headwaters basins including Reynolds Mountain East, Idaho, USA, Wolf Creek, Yukon in Canada, and Zugspitze Mountain, Germany with climates ranging from arctic to continental temperate were used to study the snow and streamflow sensitivity to climate change. All research sites have detailed multi-decadal meteorological and snow measurements. The Cold Regions Hydrological Modelling platform (CRHM) was used to create a model representing a typical alpine headwater basin discretized into hydrological response units with physically based representations of snow redistribution by wind, complex terrain snowmelt energetics and runoff processes in alpine tundra. The sensitivity of snow hydrology to climate change was investigated by changing air temperature and precipitation using weather generating methods based on the change factors obtained from different climate model projections for future and current periods. The basin mean and spatial variability of peak snow water equivalent, sublimation loss, duration of snow season, snowmelt rates, streamflow peak, and basin discharge were assessed under varying climate scenarios and the most sensitive hydrological mechanisms to the changes in the different alpine climates were detected. The results show that snow hydrology in colder alpine climates is more resilient to warming than that in warmer climates, but that compensatory factors to warming such as reduced blowing snow sublimation loss and reduced melt rate should also be assessed when considering climate change impacts on alpine hydrology.

  10. Climate-induced changes in lake ecosystem structure inferred from coupled neo- and paleoecological approaches

    USGS Publications Warehouse

    Saros, Jasmine E.; Stone, Jeffery R.; Pederson, Gregory T.; Slemmons, Krista; Spanbauer, Trisha; Schliep, Anna; Cahl, Douglas; Williamson, Craig E.; Engstrom, Daniel R.

    2015-01-01

    Over the 20th century, surface water temperatures have increased in many lake ecosystems around the world, but long-term trends in the vertical thermal structure of lakes remain unclear, despite the strong control that thermal stratification exerts on the biological response of lakes to climate change. Here we used both neo- and paleoecological approaches to develop a fossil-based inference model for lake mixing depths and thereby refine understanding of lake thermal structure change. We focused on three common planktonic diatom taxa, the distributions of which previous research suggests might be affected by mixing depth. Comparative lake surveys and growth rate experiments revealed that these species respond to lake thermal structure when nitrogen is sufficient, with species optima ranging from shallower to deeper mixing depths. The diatom-based mixing depth model was applied to sedimentary diatom profiles extending back to 1750 AD in two lakes with moderate nitrate concentrations but differing climate settings. Thermal reconstructions were consistent with expected changes, with shallower mixing depths inferred for an alpine lake where treeline has advanced, and deeper mixing depths inferred for a boreal lake where wind strength has increased. The inference model developed here provides a new tool to expand and refine understanding of climate-induced changes in lake ecosystems.

  11. Lake Powell

    NASA Technical Reports Server (NTRS)

    2007-01-01

    The white ring around Lake Powell tells the story. The surface is down 98 feet. This is critical, because Powell, Lake Mead, and other lakes along the Colorado River provide water for millions of people in five states. We are in the eighth year of a drought on the Colorado River. This year was the driest year ever reported in Southern California, and there is a severe drought in Northern California, down to less than 30-percent of snow pack. This ASTER image of part of Lake Powell was acquired in 2001. The gray area depicts the shrunken, reduced 2007 lake extent compared to the extended, larger black area in 2001.

    The image covers an area of 24 x 30 km, and is centered near 37.1 degrees north latitude, 111.3 degrees west longitude.

    The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

  12. Soil moisture mediates alpine life form and community productivity responses to warming.

    PubMed

    Winkler, Daniel E; Chapin, Kenneth J; Kueppers, Lara M

    2016-06-01

    Climate change is expected to alter primary production and community composition in alpine ecosystems, but the direction and magnitude of change is debated. Warmer, wetter growing seasons may increase productivity; however, in the absence of additional precipitation, increased temperatures may decrease soil moisture, thereby diminishing any positive effect of warming. Since plant species show individual responses to environmental change, responses may depend on community composition and vary across life form or functional groups. We warmed an alpine plant community at Niwot Ridge, Colorado continuously for four years to test whether warming increases or decreases productivity of life form groups and the whole community. We provided supplemental water to a subset of plots to alleviate the drying effect of warming. We measured annual above-ground productivity and soil temperature and moisture, from which we calculated soil degree days and adequate soil moisture days. Using an information-theoretic approach, we observed that positive productivity responses to warming at the community level occur only when warming is combined with supplemental watering; otherwise we observed decreased productivity. Watering also increased community productivity in the absence of warming. Forbs accounted for the majority of the productivity at the site and drove the contingent community response to warming, while cushions drove the generally positive response to watering and graminoids muted the community response. Warming advanced snowmelt and increased soil degree days, while watering increased adequate soil moisture days. Heated and watered plots had more adequate soil moisture days than heated plots. Overall, measured changes in soil temperature and moisture in response to treatments were consistent with expected productivity responses. We found that available soil moisture largely determines the responses of this forb-dominated alpine community to simulated climate warming. PMID

  13. In situ effects of elevated CO 2 on chlorophyll fluorescences and chloroplast pigments of alpine plant

    NASA Astrophysics Data System (ADS)

    Thron, Ch.; Hahn, K.; Lütz, C.

    Alpine vegetation responds to elevated CO 2 with downward adjustment of photosynthesis. The experiments should show if doubling of ambient CO 2 reduces the maximum quantum yield and the chlorophylls thus altering the pigment composition of the thylakoid membranes in typical species of an alpine grassland ( Caricetum curvulae). The studies were part of a CO 2 enrichment experiment with open-top chambers in the Swiss Central Alps in 2 470 m altitude over a period of four years. The leaves of Carex curvula and Trifolium alpinum were analysed in situ under ambient (355 μl/l) or elevated (680 μl/l) CO 2 and at two different nutrient levels. In each vegetation period both species showed a tendency to lower ratios of variable to maximum fluorescence (F v/F m) in plants with elevated CO 2 treatment compared to the ambient variants. These reductions in F v/F m were statistically different only for Carex curvula in 1993 and 1995. CO 2 enrichment caused reductions of leaf pigment concentrations of 10-30% especially for Trifolium alpinum whereas Carex curvula was less affected. The lower pigment contents per leaf were probably due to reductions of thylakoid membranes. In most cases, the influences of elevated CO 2 or of nutrient treatments on pigment composition and primary photochemistry were very small. This indicates that the downward regulation begins at early stages in the photosynthetic process. Some changes of the photosynthetic apparatus are species-specific and possibly reflect different strategies of protective acclimation processes of alpine vegetation.

  14. Quantifying Recent Ecological Changes in Remote Lakes of North America and Greenland Using Sediment Diatom Assemblages

    PubMed Central

    Hobbs, William O.; Telford, Richard J.; Birks, H. John B.; Saros, Jasmine E.; Hazewinkel, Roderick R. O.; Perren, Bianca B.; Saulnier-Talbot, Émilie; Wolfe, Alexander P.

    2010-01-01

    Background Although arctic lakes have responded sensitively to 20th-century climate change, it remains uncertain how these ecological transformations compare with alpine and montane-boreal counterparts over the same interval. Furthermore, it is unclear to what degree other forcings, including atmospheric deposition of anthropogenic reactive nitrogen (Nr), have participated in recent regime shifts. Diatom-based paleolimnological syntheses offer an effective tool for retrospective assessments of past and ongoing changes in remote lake ecosystems. Methodology/Principal Findings We synthesized 52 dated sediment diatom records from lakes in western North America and west Greenland, spanning broad latitudinal and altitudinal gradients, and representing alpine (n = 15), arctic (n = 20), and forested boreal-montane (n = 17) ecosystems. Diatom compositional turnover (β-diversity) during the 20th century was estimated using Detrended Canonical Correspondence Analysis (DCCA) for each site and compared, for cores with sufficiently robust chronologies, to both the 19th century and the prior ∼250 years (Little Ice Age). For both arctic and alpine lakes, β-diversity during the 20th century is significantly greater than the previous 350 years, and increases with both latitude and altitude. Because no correlation is apparent between 20th-century diatom β-diversity and any single physical or limnological parameter (including lake and catchment area, maximum depth, pH, conductivity, [NO3−], modeled Nr deposition, ambient summer and winter air temperatures, and modeled temperature trends 1948–2008), we used Principal Components Analysis (PCA) to summarize the amplitude of recent changes in relationship to lake pH, lake:catchment area ratio, modeled Nr deposition, and recent temperature trends. Conclusions/Significance The ecological responses of remote lakes to post-industrial environmental changes are complex. However, two regions reveal concentrations of sites

  15. Global patterns in lake surface temperature trends

    NASA Astrophysics Data System (ADS)

    O'Reilly, C.; Sharma, S.; Gray, D.; Hampton, S. E.; Read, J. S.; Rowley, R.; McIntyre, P. B.; Lenters, J. D.; Schneider, P.; Hook, S. J.

    2014-12-01

    Temperature profoundly affects dynamics in the water bodieson which human societies depend worldwide. Even relatively small water temperature changes can alter lake thermal structure with implications for water level, nutrient cycling, ecosystem productivity, and food web dynamics. As air temperature increases with climate change and human land use transforms watersheds, rising water temperatures have been reported for individual lakes or regions, but a global synthesis is lacking; such a synthesis is foundational for understanding the state of freshwater resources. We investigated global patterns in lake surface water temperatures between 1985 and 2009 using in-situ and satellite data from 236 lakes. We demonstrate that lakes are warming significantly around the globe, at an average rate of 0.34 °C per decade. The breadth of lakes in this study allowed examination of the diversity of drivers across global lakes, and highlighted the importance of ice cover in determining the suite of morphological and climate drivers for lake temperature dynamics. These empirical results are consistent with modeled predictions of climate change, taking into account the extent to which water warming can be modulated by local environmental conditions and thus defy simple correlations with air temperature. The water temperature changes we report have fundamental importance for thermal structure and ecosystem functioning in global water resources; recognition of the extent to which lakes are currently in transition should have broad implications for regional and global models as well as for management.

  16. Organic carbon input from atmospheric deposition: a potential driver of nitrogen export from barren alpine ecosystems (Invited)

    NASA Astrophysics Data System (ADS)

    Mladenov, N.; Williams, M. W.; Schmidt, S. K.

    2010-12-01

    There is urgency to improve our understanding of how biogeochemical cycling and surface water quality in high-elevation catchments will respond to a combination of changes in climate, atmospheric deposition of pollutants, and potential increases in dust deposition. Previous work has shown that atmospheric wet and dry deposition is an important source of dissolved organic matter for alpine lakes, with important consequences for aquatic ecosystem functioning. Here we investigate new linkages between atmospheric deposition of organic matter and terrestrial biogeochemical processes, namely nitrification. Our goal is to better understand the substantial increase in mean annual nitrogen (N) export that has been observed in Rocky Mountain and other alpine watersheds, while N deposition rates have remained constant. The combination of increasing temperatures and dust emissions, melting glaciers, and surprisingly high amounts of microbial activity in recently deglaciated soils, suggest that carbon (C) cycling in these barren alpine catchments may have an important and, thus far, unexplored role in nitrification and N export. Our results show that the quantity of atmospheric organic carbon inputs approaches that of biological C fixation in magnitude. We hypothesize that heterotrophic processing of atmospheric and autotrophic C inputs and the resulting increased availability of amine compounds may enhance nitrification and intensify N export from alpine catchments. Results from optical spectroscopy further demonstrate that water soluble organic carbon from atmospheric deposition has low aromaticity, is high in amino acid-like moieties (Figure 1), and may represent a labile carbon source for terrestrial and aquatic alpine microorganisms. Fig 1. TOP: Fluorescence excitation emission matrix (EEM) of a representative wet deposition sample (collected 24-30 June, 2009 at Niwot Ridge, Colorado). FI = fluorescence index; SUVA = specific UV absorbance (L mg-1 m-1); AA = amino acid

  17. Nitrogen deposition and warming - effects on phytoplankton nutrient limitation in subarctic lakes.

    PubMed

    Bergström, Ann-Kristin; Faithfull, Carolyn; Karlsson, Daniel; Karlsson, Jan

    2013-08-01

    The aim of this study was to predict the combined effects of enhanced nitrogen (N) deposition and warming on phytoplankton development in high latitude and mountain lakes. Consequently, we assessed, in a series of enclosure experiments, how lake water nutrient stoichiometry and phytoplankton nutrient limitation varied over the growing season in 11 lakes situated along an altitudinal/climate gradient with low N-deposition (<1 kg N ha(-1)  yr(-1) ) in northern subarctic Sweden. Short-term bioassay experiments with N- and P-additions revealed that phytoplankton in high-alpine lakes were more prone to P-limitation, and with decreasing altitude became increasingly N- and NP-colimited. Nutrient limitation was additionally most obvious in midsummer. There was also a strong positive correlation between phytoplankton growth and water temperature in the bioassays. Although excess nutrients were available in spring and autumn, on these occasions growth was likely constrained by low water temperatures. These results imply that enhanced N-deposition over the Swedish mountain areas will, with the exception of high-alpine lakes, enhance biomass and drive phytoplankton from N- to P-limitation. However, if not accompanied by warming, N-input from deposition will stimulate limited phytoplankton growth due to low water temperatures during large parts of the growing season. Direct effects of warming, allowing increased metabolic rates and an extension of the growing season, seem equally crucial to synergistically enhance phytoplankton development in these lakes. PMID:23629960

  18. Potentially dangerous glacial lakes in Kyrgyzstan - Research overview of 2004-2015

    NASA Astrophysics Data System (ADS)

    Jansky, Bohumir; Yerokhin, Sergey; Sobr, Miroslav; Engel, Zbynek; Cerny, Michal; Falatkova, Kristyna; Kocum, Jan; Benes, Vojtech

    2016-04-01

    Global warming causes intensive melting and retreat of glaciers in most of high mountains all over the world. This process is also evident in the mountain regions of central Tien Shan. Glacier melt water affects changes in hydrological regime of water streams and causes overfilling of high mountain lake basins. The dams of many lakes are very unstable and can burst open. To determine the degree of such risk, it is necessary to analyse the genesis of lakes, to characterize the morphology of the lake basins and to know the particularities of their hydrological regime. According to the latest inventory within territory of Kyrgyzstan, a total of 1328 lakes have been identified as potentially dangerous, 12 lakes are considered as currently dangerous, other 25 feature high potential hazard. Since 1952 more than 70 disastrous cases of lake outburst have been registered. The hazardous alpine lakes are studied in Kyrgyzstan systematically since 1966. Since 2004, Czech-Kyrgyz research team has been operating in Kyrgyzstan in the field of dangerous glacial lakes. Projects were focused primarily on high-mountain glacial lakes risk assessment, propositions of risk mitigation measures, establishment of permanent research station near one of the studied glacier complexes, preparation of risk analysis for selected endangered valleys, evaluation of climatic and hydrological data and glacier development within observed regions. The most significant portion of data and information has been gathered during field work, complemented by satellite image analysis and surveillance flights over the monitored sites.

  19. Alpine Skiing With total knee ArthroPlasty (ASWAP): effect on tendon properties.

    PubMed

    Kösters, A; Rieder, F; Wiesinger, H-P; Dorn, U; Hofstaedter, T; Fink, C; Müller, E; Seynnes, O R

    2015-08-01

    The aim of this study was to investigate the effect of alpine skiing on patellar tendon properties in patients with total knee arthroplasty (TKA). Thirty-one adults (70.4 ± 4.7 years) with unilateral TKA were recruited 2.7 ± 0.9 years after surgery and assigned to an intervention (IG) or a control group (CG). The IG underwent a 12-week guided skiing program. Tendon stiffness, Young's modulus, and cross-sectional area (CSA) were measured before and after the intervention. In both groups, mean tendon CSA was 28% (P < 0.001) larger in the operated (OP) than in the non-operated (NOP) leg at baseline, without any difference in other tendon properties. After training, stiffness increased in the IG by 5.8% and 15.8%, respectively, in the OP and NOP legs. Likewise, mean CSA increased in the IG by 2.9% in the OP and 3.8% in the NOP leg, whereas no significant changes were found for the Young's modulus. None of the tendon parameters changed in the CG. Results indicate that patellar tendon structure and/or loading pattern are altered following TKA, but this tissue seems to retain its adaptation capacity. Further, alpine skiing appears to offer a suitable rehabilitation strategy for TKA patients. PMID:26083704

  20. Influences of alpine ecosystem degradation on soil temperature in the freezing-thawing process on Qinghai-Tibet Plateau

    NASA Astrophysics Data System (ADS)

    Hu, Hongchang; Wang, Genxu; Liu, Guangsheng; Li, Taibing; Ren, Dongxing; Wang, Yibo; Cheng, Huiyan; Wang, Junfeng

    2009-05-01

    The alpine ecosystem is very sensitive to environmental change due to global and local disturbances. The alpine ecosystem degradation, characterized by reducing vegetation coverage or biomass, has been occurring in the Qinghai-Tibet Plateau, which alters local energy balance, and water and biochemical cycles. However, detailed characterization of the ecosystem degradation effect is lack in literature. In this study, the impact of alpine ecosystem degradation on soil temperature for seasonal frozen soil and permafrost are examined. The vegetation coverage is used to indicate the degree of ecosystems degradation. Daily soil temperature is monitored at different depths for different vegetation coverage, for both permafrost and seasonal frozen soils. Results show that under the insulating effort of the vegetation, the freezing and thawing process become quicker and steeper, and the start of the freezing and thawing process moves up due to the insulating effort of the vegetation. The influence of vegetation coverage on the freezing process is more evident than the thawing process; with the decrease of vegetation coverage, the integral of frozen depth increases for seasonal frozen soil, but is vice versa for permafrost.

  1. ERTS-1 views the Great Lakes

    NASA Technical Reports Server (NTRS)

    Lyons, W. A.; Pease, S. R.

    1973-01-01

    The meteorological content of ERTS images, particularly mesoscale effects of the Great Lakes and air pollution dispersion is summarized. Summertime lake breeze frontal clouds and various winter lake-effect convection patterns and snow squalls are revealed in great detail. A clear-cut spiral vortex over southern Lake Michigan is related to a record early snow storm in the Chicago area. Marked cloud changes induced by orographic and frictional effects on Lake Michigan's lee shore snow squalls are seen. The most important finding, however, is a clear-cut example of alterations in cumulus convection by anthropogenic condensation and/or ice nuclei from northern Indiana steel mills during a snow squall situation. Jet aircraft condensation trails are also found with surprising frequency.

  2. Quantifying instantaneous performance in alpine ski racing.

    PubMed

    Federolf, Peter Andreas

    2012-01-01

    Alpine ski racing is a popular sport in many countries and a lot of research has gone into optimising athlete performance. Two factors influence athlete performance in a ski race: speed and the chosen path between the gates. However, to date there is no objective, quantitative method to determine instantaneous skiing performance that takes both of these factors into account. The purpose of this short communication was to define a variable quantifying instantaneous skiing performance and to study how this variable depended on the skiers' speed and on their chosen path. Instantaneous skiing performance was defined as time loss per elevation difference dt/dz, which depends on the skier's speed v(z), and the distance travelled per elevation difference ds/dz. Using kinematic data collected in an earlier study, it was evaluated how these variables can be used to assess the individual performance of six ski racers in two slalom turns. The performance analysis conducted in this study might be a useful tool not only for athletes and coaches preparing for competition, but also for sports scientists investigating skiing techniques or engineers developing and testing skiing equipment. PMID:22620279

  3. Geophysical imaging of alpine rock glaciers

    NASA Astrophysics Data System (ADS)

    Maurer, Hansruedi; Hauck, Christian

    Slope instabilities caused by the disappearance of ice within alpine rock glaciers are an issue of increasing concern. Design of suitable counter-measures requires detailed knowledge of the internal structures of rock glaciers, which can be obtained using geophysical methods. We examine benefits and limitations of diffusive electromagnetics, geoelectrics, seismics and ground-penetrating radar (georadar) for determining the depth and lateral variability of the active layer, the distributions of ice and water, the occurrence of shear horizons and the bedrock topography. In particular, we highlight new developments in data acquisition and data analysis that allow 2-D or even 3-D structures within rock glaciers to be imaged. After describing peculiarities associated with acquiring appropriate geophysical datasets across rock glaciers and emphasizing the importance of state-of-the-art tomographic inversion algorithms, we demonstrate the applicability of 2-D imaging techniques using two case studies of rock glaciers in the eastern Swiss Alps. We present joint interpretations of geoelectric, seismic and georadar data, appropriately constrained by information extracted from boreholes. A key conclusion of our study is that the different geophysical images are largely complementary, with each image resolving a different suite of subsurface features. Based on our results, we propose a general template for the cost-effective and reliable geophysical characterization of mountain permafrost.

  4. Annual variability of ozone along alpine hillsides

    NASA Technical Reports Server (NTRS)

    Putz, Erich; Kosmus, Walter

    1994-01-01

    Over a period of more than two years (March 1989 till June 1991) ozone and nitrogen dioxide have been monitored along twelve alpine hillsides in the Austrian alps. The profiles had a height-resolution of 100 m and cover a range between 400 m and 1800 m asl, that is 100 m to 1100 m above the bottom of the valleys. They were situated in remote rural areas as well as in the vicinity of polluted urban and industrial areas. Both trace gases were monitored by means of integral chemical (SAM-surface active monitor) methods with a measuring cycle of two weeks. The concentration of ozone exhibits a substantial annual variation over the entire height range. In summer, highest ozone levels are observed near the ground and at the top of the mountains, whereas in winter the maxima are found mainly in the crest regions. The overall ozone burden shows a relative maximum near the temperature inversion layer in the valleys and an absolute maximum at the crest.

  5. Aortic Dissection Type A in Alpine Skiers

    PubMed Central

    Schachner, Thomas; Fischler, Nikolaus; Dumfarth, Julia; Bonaros, Nikolaos; Krapf, Christoph; Schobersberger, Wolfgang; Grimm, Michael

    2013-01-01

    Patients and Methods. 140 patients with aortic dissection type A were admitted for cardiac surgery. Seventy-seven patients experienced their dissection in the winter season (from November to April). We analyzed cases of ascending aortic dissection associated with alpine skiing. Results. In 17 patients we found skiing-related aortic dissections. Skiers were taller (180 (172–200) cm versus 175 (157–191) cm, P = 0.008) and heavier (90 (68–125) kg versus 80 (45–110) kg, P = 0.002) than nonskiers. An extension of aortic dissection into the aortic arch, the descending thoracic aorta, and the abdominal aorta was found in 91%, 74%, and 69%, respectively, with no significant difference between skiers and nonskiers. Skiers experienced RCA ostium dissection requiring CABG in 17.6% while this was true for 5% of nonskiers (P = 0.086). Hospital mortality of skiers was 6% versus 13% in nonskiers (P = 0.399). The skiers live at an altitude of 170 (0–853) m.a.s.l. and experience their dissection at 1602 (1185–3105; P < 0.001) m.a.s.l. In 82% symptom start was during recreational skiing without any trauma. Conclusion. Skiing associated aortic dissection type A is usually nontraumatic. The persons affected live at low altitudes and practice an outdoor sport at unusual high altitude at cold temperatures. Postoperative outcome is good. PMID:23971024

  6. Environmental controls on alpine cirque size

    NASA Astrophysics Data System (ADS)

    Delmas, Magali; Gunnell, Yanni; Calvet, Marc

    2014-02-01

    Pleistocene alpine cirques are emblematic landforms of mountain scenery, yet their deceptively simple template conceals complex controlling variables. This comparative study presents a new database of 1071 cirques, the largest of its kind, located in the French eastern Pyrenees. It is embedded in a review of previous work on cirque morphometry and thus provides a perspective on a global scale. First-order cirque attributes of length, width, and amplitude were measured; and their power as predictors of climatic and lithological variables and as proxies for the duration of glacier activity was tested using ANOVA, simple and multiple linear regression, and their various post-hoc tests. Conventional variables such as cirque aspect, floor elevation, and exposure with respect to regional precipitation-bearing weather systems are shown to present some consistency in spatial patterns determined by solar radiation, the morning-afternoon effect, and wind-blown snow accumulation in the lee of ridgetops. This confirms in greater detail the previously encountered links between landforms and climate. A special focus on the influence of bedrock lithology, a previously neglected nonclimatic variable, highlights the potential for spurious relations in the use of cirque size as a proxy of past environmental conditions. Cirques are showcased as complex landforms resulting from the combination of many climatic and nonclimatic variables that remain difficult to rank by order of importance. Apart from a few statistically weak trends, several combinations of different factors in different proportions are shown to produce similar morphometric outcomes, suggesting a case of equifinality in landform development.

  7. Minimal erosion of Arctic alpine topography during late Quaternary glaciation

    NASA Astrophysics Data System (ADS)

    Gjermundsen, Endre F.; Briner, Jason P.; Akçar, Naki; Foros, Jørn; Kubik, Peter W.; Salvigsen, Otto; Hormes, Anne

    2015-10-01

    The alpine topography observed in many mountainous regions is thought to have formed during repeated glaciations of the Quaternary period. Before this time, landscapes had much less relief. However, the spatial patterns and rates of Quaternary exhumation at high latitudes--where cold-based glaciers may protect rather than erode landscapes--are not fully quantified. Here we determine the exposure and burial histories of rock samples from eight summits of steep alpine peaks in northwestern Svalbard (79.5° N) using analyses of 10Be and 26Al concentrations. We find that the summits have been preserved for at least the past one million years. The antiquity of Svalbard’s alpine landscape is supported by the preservation of sediments older than one million years along a fjord valley, which suggests that both mountain summits and low-elevation landscapes experienced very low erosion rates over the past million years. Our findings support the establishment of northwestern Svalbard’s alpine topography during the early Quaternary. We suggest that, as the Quaternary ice age progressed, glacial erosion in the Arctic became inefficient and confined to ice streams, and high-relief alpine landscapes were preserved by minimally erosive glacier armour.

  8. Comparison among different downscaling approaches in building water scarcity scenarios in an Alpine basin.

    NASA Astrophysics Data System (ADS)

    Guyennon, Nicolas; Romano, Emanuele; Mariani, Davide; Bruna Petrangeli, Anna; Portoghese, Ivan

    2014-05-01

    Various downscaling techniques have been developed to bridge the scale gap between global climate models (GCMs) and finer scales required to assess hydrological impacts of climate change. Although statistical downscaling (SD) has been traditionally seen as an alternative to dynamical downscaling (DD), recent works on statistical downscaling have aimed to combine the benefits of these two approaches. The overall objective of this study is to assess whether a DD processing performed before the SD is able to provide more reliable climate forcing for crop water demand models. The case study presented here focuses on the Maggiore Lake (Alpine region), with a watershed of approximately 4750 km2 and whose waters are mainly used for irrigation purposes in the Lombardia and Piemonte regions. The fifth-generation ECHAM model from the Max-Planck-Institute for Meteorology was adopted as GCM. The DD was carried out with the Protheus system (ENEA), while the SD was performed through a monthly quantile-quantile correction of the precipitation data collected in the period 1950-2012 by the 19 rainfall gauges located in the watershed area (some of them operating not continuously during the study period). The relationship between the precipitation regime and the inflow to the reservoir is obtained through a simple multilinear regression model, validated using both precipitation data and inflow measurements to the lake in the period 1996-2012 then, the same relation has been applied to the control (20c) and scenario (a1b) simulations downscaled by means of the different downscaling approaches (DD, SD and combined DD-SD). The resulting forcing has been used as input to a daily water balance model taking into account the inflow to the lake, the demand for irrigation and the reservoir management policies. The impact of the different downscaling approaches on the water budget scenarios has been evaluated in terms of occurrence, duration and intensity of water scarcity periods.

  9. Synchoronous inter-hemispheric alpine glacier advances during the Late Glacial?

    NASA Astrophysics Data System (ADS)

    Bakke, Jostein; Paasche, Øyvind

    2016-04-01

    The termination of the last glaciation in both hemispheres was a period of rapid climate swings superimposed on the overall warming trend, resulting from large-scale reorganizations of the atmospheric and oceanic circulation patterns in both hemispheres. Environmental changes during the deglaciation have been inferred from proxy records, as well as by model simulations. Several oscillations took place both in northern and southern hemispheres caused by melt water releases such as during the Younger Dryas in north and the Antarctic Cold Reversal in south. However, a consensus on the hemispheric linkages through ocean and atmosphere are yet to be reached. Here we present a new multi-proxy reconstruction from a sub-annually resolved lake sediment record from Lake Lusvatnet in Arctic Norway compared with a new reconstruction from the same time interval at South Georgia, Southern Ocean, suggesting inter-hemispheric climate linkages during the Bølling/Allerød time period. Our reconstruction of the alpine glacier in the lake Lusvatnet catchment show a synchronous glacier advance with the Birch-hill moraine complex in the Southern Alps, New Zealand during the Intra Allerød Cooling period. We propose these inter hemispheric climate swings to be forced by the northward migration of the southern Subtropical Front during the Antarctic Cold Reversal. Such a northward migration of the Subtropical Front is shown in model simulation and in palaeorecords to reduce the Agulhas leakage impacting the strength of the Atlantic meridional overturning circulation. We simply ask if this can be the carrier of rapid climate swings from one hemisphere to another? Our high-resolution reconstructions provide the basis for an enhanced understanding of the tiny balance between migration of the Subtropical Front in the Southern Ocean and the teleconnection to northern hemisphere.

  10. Effect of Climate Change on Flood and Drought Risks in a Northern-Alpine catchment

    NASA Astrophysics Data System (ADS)

    Marx, A.; Mast, M.; Knoche, H. R.; Kunstmann, H.

    2009-04-01

    The Alps are particularly sensitive to climate change. Observations show that recent warming there has been roughly three times the global average. During the last decade, the northern parts of the Alps have been hit by three so-called century floods in 1999, 2002, and 2005. In this study, the effect of climate change on the water cycle in the Northern-Alpine area is investigated. Our investigations focus on the Alpine catchment of the river Alz (2100 km²) in Austria and Germany, including Lake Chiemsee. Climate simulation output from MM5 (1960-1990, 2070-99, SRES B2) and CLM (1960-2100, SRES A1B, B1) have been statistically analyzed. They show a significant increase in temperature >3°C until the end of the 21st century and a slight increase of annual precipitation, but also a changing seasonality increasing rainfall intensities. Precipitation has been bias-corrected using a method based on monthly correction factors. The Effective Drought Index EDI has been calculated using the corrected climate simulation precipitation output, showing that future drought risk increases maily in summer time. The bias-corrected climate simulation data has been transformed and applied to the distributed water balance model WaSiM to investigate changes in water balance, e.g. in river discharge and evapotranspiration, and future flooding risk in the Alz catchment. The hydrological model has been driven on a 500*500 m² raster grid with a daily timestep. An increased large scale flooding risk in future times could not be detected. Nevertheless, the future increase in precipitation intensity may cause an increased risk of scale flooding due to storms. Results from the MM5 and CLM climate simulations including drought risk are shown as well as results of the WaSiM water balance simulations including flooding risks.

  11. Abundances, diversity and seasonality of (non-extremophilic) Archaea in Alpine freshwaters.

    PubMed

    Reitschuler, Christoph; Hofmann, Katrin; Illmer, Paul

    2016-06-01

    The objectives of this study were to assess abundances and community compositions of Archaea within a heterogeneous set of freshwater systems in the Austrian Alps. Seasonal changes and geographical differences within Archaea, considering abiotic and biotic factors (e.g. temperature, pH, total organic carbon (TOC), NH4 (+), bacteria, fungi), were analysed in this context. Water samples were collected from 8 lakes, 10 creeks and the river Inn in 2014. Qualitative-quantitative data were derived via a comprehensive set of (quantitative) PCR assays and PCR-DGGE (denaturing gradient gel electrophoresis) based methodology, which was evaluated concerning specificity and reliability either previously or in this study. QPCR-derived archaeal abundances reached values of 10(3) copies mL(-1) on average, with a peak in winter-spring ('Cold Peak'), and covered 0-15 % (average: 1 %) of the microbial populations. This peak correlated with significantly raised TOC and low NH4 (+) levels during the cold seasons. Stagnant waters showed significantly higher archaeal abundances and diversities than flowing ones. Among methanogens, Methanosarcinales were the most common order. PCR-DGGE data showed that the archaeal communities were site-specific and could function as an ecological marker, in contrast to the more heterogeneous and unsteady bacterial and fungal community. This is attributable to the highly heterogeneous community of methanogenic Archaea (MA, Euryarchaeota), while only two species, Nitrosopumilus maritimus and Ca. Nitrososphaera gargensis, were found to be the ubiquitous representatives of ammonia-oxidizing Archaea (AOA, Thaumarchaeota) in Alpine freshwaters. This work emphasises the diversity, distribution and seasonality of non-extremophilic Archaea in Alpine freshwaters, with a first insight into their ecophysiological potential. PMID:27002962

  12. Using deuterium excess to determine the sources of high-altitude precipitation: Implications in hydrological relations between sub-alpine forests and alpine meadows

    NASA Astrophysics Data System (ADS)

    Cui, Jun; An, Shuqing; Wang, Zhongsheng; Fang, Changming; Liu, Yuhong; Yang, Haibo; Xu, Zhen; Liu, Shirong

    2009-06-01

    SummaryAlpine meadows in the upper catchments of the Yangtze River, China provide critical amounts of water to maintain regional water resources, but little is known about the hydrological processes in these alpine ecosystems. In this paper, we analyzed the sources of precipitation in an alpine meadow using the deuterium excess in rain, fog, soil water, shallow groundwater and stream water. Rain and fog in the alpine meadow had high deuterium excess, 35‰ and 38‰ compared to 10‰ of precipitation brought by monsoon at lower elevation. These high values suggested that a large part of rain at the alpine meadow derived from secondarily evaporated water and that fog derived from the evaporated water produced shortly after rain events. However, averaged evaporation rate calculated by an isotopic mass balance model of soil water was only 0.26 mm/d, about 3.6% of the rainfall and 7.57‰ of the average deuterium excess value of rain. The contribution from evaporated water to precipitation in the alpine meadow therefore had to be mainly from sub-alpine vegetations in the region. This eco-hydrological relation between sub-alpine and alpine ecosystems can partly explain the high water yield of the alpine meadow and should be considered for regional resource management.

  13. The individual response of saline lakes to a severe drought.

    PubMed

    Tweed, Sarah; Grace, Mike; Leblanc, Marc; Cartwright, Ian; Smithyman, Donna

    2011-09-01

    A severe protracted drought between 1997 and 2009 has altered the physical and chemical hydrology of a series of lakes in the Corangamite Basin of southeast Australia. Leading up to the drying out of most lakes (many for the first time on record), we document the changes in lakes' water quantity (water levels and inundation), salinity (Cl concentrations), salinity processes (Cl/Br ratios), nutrient concentrations and ratios (ammonia, phosphate and NOx (nitrate and nitrite)) and algae (as chlorophyll-a) for six lakes. All lakes show record declines in inundated areas and increases in salinity from pre-drought (<1997) to drought conditions. However, the magnitude of change in salinity varies for different lakes, and there is no systematic change in the controls on lake salinity processes. Four lakes show no change in salinity processes, one lake shows the beginnings of change; where halite dissolution reactions increased closer to the time of the lake drying up, and another lake shows a marked shift from predominantly evaporation to the cyclic dissolution and precipitation of halite. Changes in filterable reactive phosphorus (FRP) values and lake N and P limitation predictions also showed little systematic correlation with changes in lake salinity, and nutrient values varied between lakes and over time. The decline in NO(x) concentrations in lakes where electrical conductivity (EC) values were above 100 mS/cm indicates some correlation with changes in salinity. Largely, these lakes exhibit individual changes in water quality parameters and salinity processes in response to the drought, indicating that while the stress of drought is regional, the hydrochemical response is local. In future changing climates, these results suggest that the catchment adaption strategies will require comprehensive plans for individual lake systems. PMID:21752428

  14. Does Rock Mass Strength Control the Rate of Alpine Cliff Erosion?

    NASA Astrophysics Data System (ADS)

    Moore, J. R.; Sanders, J. W.; Dietrich, W. E.; Glaser, S. D.

    2007-12-01

    Collapse of cliff faces by rockfall is a primary mode of bedrock erosion in alpine environments and plays a controlling role in mass removal from these systems. In this work we investigate the influence of rock mass strength on the retreat rate of alpine rock slopes. To quantify rockwall competence we employed the Slope Mass Rating (SMR) geomechanical strength index, which combines numerous factors that affect the strength of a rock mass, such as intact rock strength, joint frequency, joint condition, and more. The magnitude of cliff retreat was calculated by estimating the volume of talus at the toe of each rockwall and projecting that material back onto the cliff face, while accounting for the loss of production area as talus buries the base of the wall. Selecting sites within basins swept clean by advancing LGM glaciers allowed us to estimate the time period over which talus accumulation occurred (i.e. the production time). Dividing the magnitude of normal cliff retreat by the production time, we calculated erosion rates for each site. Our study area included a portion of the Sierra Nevada from Yosemite National Park in the south to Lake Tahoe in the north. Rockwall recession rates determined for 40 alpine cliffs in this region varied from 0.02 to 1.22 mm/year, with an average value of 0.28 mm/year. We found good correlation between rockwall recession rate and SMR that is best characterized by an exponential decrease in erosion rate with increasing rock mass strength. Analysis of the individual components of the SMR reveals that joint orientation (with respect to the cliff face) is the most important parameter affecting the rockwall erosion rate. The complete SMR score, however, best synthesizes the lithologic variables that contribute to the strength and erodibility of these rock slopes. Our data reveal no strong independent correlation between the measured rockwall retreat rate and environmental attributes (such as site elevation, aspect, cliff slope length

  15. A calibration curve at 2000 meters (A.S.L.): alpine valleys as field laboratories for teaching environmental monitoring to undergraduate students.

    PubMed

    Dossi, Carlo; Monticelli, Damiano; Pozzi, Andrea; Recchia, Sandro; Vezzoli, Luigina

    2002-04-01

    High-altitude alpine valleys may be considered as ideal field laboratories for the interdisciplinary teaching of Environmental Sciences to undergraduate students in a Laurea degree, since different typologies of sampling sites (rivers, lakes, glaciers) may be found within walking distance, and students are encouraged to develop cooperative learning activities. Scientific data have been collected by 1st year students at the University of Insubria in Como during a teaching program in Ventina Valley and Caronno Valley near Sondrio (Italy). Analytical and geochemical results will be presented and discussed on the basis of organic deposition and water-rock interactions. PMID:12073886

  16. Integrating Physical and Chemical Characteristics of Lakes into the Glacially Influenced Landscape of the Northern Cascade Mountains, Washington State, USA.

    PubMed

    Larson; Lomnicky; Hoffman; Liss; Deimling

    1999-09-01

    / A basic knowledge of the physical and chemical characteristics of lakes is needed by management to make informed decisions to protect water resources. In this study we investigated some of the physical and chemical characteristics of 58 lakes in alpine, subalpine, and forest vegetation zones in a natural area (North Cascades National Park Service Complex) between 1989 and 1993. The objectives of the study were to: (1) document the time of ice-out relative to lake elevation; (2) determine how a sharp climate gradient west and east of the hydrologic divide affected the time of ice-out for subalpine lakes; and (3) assess how lake water quality was associated with lake elevation, lake depth, and basin geology. As expected, lake ice-out times occurred earlier with decreasing elevation. East-slope subalpine lakes iced-out earlier than did west-slope subalpine lakes because the east slope of the study area was drier and warmer than the west slope. On average, the lakes were relatively cold, neutral in pH, and low in dissolved substances and concentrations of nitrogen and phosphorus. Although some shallow lakes (depth <10 m) exhibited the highest alkalinities, conductivities, and concentrations of phosphorus and nitrogen, most shallow lakes exhibited low values for these variables that were comparable to values observed in deep lakes. Geology did not play a major role in segregating the lakes based on water quality. Overall, lake temperature, pH, alkalinity, conductivity, and concentrations of total phosphorus and total Kjeldahl N increased with decreasing elevation. These changes in water quality with decreasing elevation in this temperate mountainous region corresponded with warmer air temperatures and increased vegetation biomass, soil depth and maturity, and dissolved substances and nutrients.KEY WORDS: Limnology; Mountain lakes; Water quality; North Cascades National Park Service Complex; National Park Servicehttp://link.springer-ny.com/link/service/journals/00267

  17. Sensitivity of alpine watersheds to global change

    NASA Astrophysics Data System (ADS)

    Zierl, B.; Bugmann, H.

    2003-04-01

    Mountains provide society with a wide range of goods and services, so-called mountain ecosystem services. Besides many others, these services include the most precious element for life on earth: fresh water. Global change imposes significant environmental pressure on mountain watersheds. Climate change is predicted to modify water availability as well as shift its seasonality. In fact, the continued capacity of mountain regions to provide fresh water to society is threatened by the impact of environmental and social changes. We use RHESSys (Regional HydroEcological Simulation System) to analyse the impact of climate as well as land use change (e.g. afforestation or deforestation) on hydrological processes in mountain catchments using sophisticated climate and land use scenarios. RHESSys combines distributed flow modelling based on TOPMODEL with an ecophysiological canopy model based on BIOME-BGC and a climate interpolation scheme based on MTCLIM. It is a spatially distributed daily time step model designed to solve the coupled cycles of water, carbon, and nitrogen in mountain catchments. The model is applied to various mountain catchments in the alpine area. Dynamic hydrological and ecological properties such as river discharge, seasonality of discharge, peak flows, snow cover processes, soil moisture, and the feedback of a changing biosphere on hydrology are simulated under current as well as under changed environmental conditions. Results of these studies will be presented and discussed. This project is part of an over overarching EU-project called ATEAM (acronym for Advanced Terrestrial Ecosystem Analysis and Modelling) assessing the vulnerability of European ecosystem services.

  18. Tagliamento, the king of Alpine rivers

    NASA Astrophysics Data System (ADS)

    Imbriani, Nadia

    2016-04-01

    The Tagliamento river is usually described as the king of the Alpine rivers because it is an extraordinary example of braided gravel-bed river in Europe. It flows in Friuli Venezia Giulia, a region in north-eastern Italy. It has preserved its original ecosystem which has never been changed significantly by irresponsible human interference. Therefore, vegetated islands and braid bars, due to the typical network of channels the river creates, have always been an uncontaminated natural habitat for a wide variety of species of flora and fauna. The Pinzano Bridge, near San Daniele del Friuli, collapsed on 4th November 1966 because of an overflow of water from Tagliamento. From that time, lowlands territorial authorities would like to build retention basins to prevent the river from floodings. A study about the bio-geological survey carried out from a Manzini High School project, chiefly aims to study this ecosystem, which combines the dynamic nature of the Tagliamento with the biodiversity of the whole area where it flows. In the previous years, some classes were involved in this school project. After visiting the river area and taking several photographs of it, the students had the opportunity to reflect upon the devastating environmental impact which the construction of retention basins would cause. They illustrated and analyzed both the solutions offered by some local governors and the objections raised by the World Wide Fund For Nature (WWF). In the near future, other students will continue studying the Tagliamento river so as to be able to appreciate one of the local rarities nature offers, in the hope that the unique geomorphological features of this site of undoubted scientific interest could be kept intact for a very long time.

  19. Alkali content of alpine ultramafic rocks

    USGS Publications Warehouse

    Hamilton, W.; Mountjoy, W.

    1965-01-01

    The lower limit of abundance of sodium and potassium in ultramafic rocks is less than the threshold amount detectable by conventional analytical methods. By a dilutionaddition modification of the flame-spectrophotometric method, sodium and potassium have been determined in 40 specimens of alpine ultramafic rocks. Samples represent six regions in the United States and one in Australia, and include dunite, peridotite, pyroxenite, and their variably serpentinized and metamorphosed derivatives. The median value found for Na2O is 0.004 per cent, and the range of Na2O is 0.001-0.19. The median value for K2O is 0.0034 per cent and the range is 0.001-0.031 per cent. Alkali concentrations are below 0.01 per cent Na2O in 28 samples and below 0.01 per cent K2O in 35. Derivation of basalt magma from upper-mantle material similar to such ultramafic rocks, as has been postulated, is precluded by the relative amounts of sodium and potassium, which are from 200 to 600 times more abundant in basalt than in the ultramafic rocks. Similar factors apply to a number of other elements. No reasonable process could produce such concentrations in, for example, tens of thousands of cubic miles of uniform tholeiitic basalt. The ultramafic rocks might have originated either as magmatic crystal precipitates or as mantle residues left after fusion and removal of basaltic magma. Injection of ultramafic rocks to exposed positions is tectonic rather than magmatic. ?? 1965.

  20. Simulating Lake-Groundwater Interactions During Decadal Climate Cycles: Accounting For Variable Lake Area In The Watershed

    NASA Astrophysics Data System (ADS)

    Virdi, M. L.; Lee, T. M.

    2009-12-01

    The volume and extent of a lake within the topo-bathymetry of a watershed can change substantially during wetter and drier climate cycles, altering the interaction of the lake with the groundwater flow system. Lake Starr and other seepage lakes in the permeable sandhills of central Florida are vulnerable to climate changes as they rely exclusively on rainfall and groundwater for inflows in a setting where annual rainfall and recharge vary widely. The groundwater inflow typically arrives from a small catchment area bordering the lake. The sinkhole origin of these lakes combined with groundwater pumping from underlying aquifers further complicate groundwater interactions. Understanding the lake-groundwater interactions and their effects on lake stage over multi-decadal climate cycles is needed to manage groundwater pumping and public expectation about future lake levels. The interdependence between climate, recharge, changing lake area and the groundwater catchment pose unique challenges to simulating lake-groundwater interactions. During the 10-year study period, Lake Starr stage fluctuated more than 13 feet and the lake surface area receded and expanded from 96 acres to 148 acres over drier and wetter years that included hurricanes, two El Nino events and a La Nina event. The recently developed Unsaturated Zone Flow (UZF1) and Lake (LAK7) packages for MODFLOW-2005 were used to simulate the changing lake sizes and the extent of the groundwater catchment contributing flow to the lake. The lake area was discretized to occupy the largest surface area at the highest observed stage and then allowed to change size. Lake cells convert to land cells and receive infiltration as receding lake area exposes the underlying unsaturated zone to rainfall and recharge. The unique model conceptualization also made it possible to capture the dynamic size of the groundwater catchment contributing to lake inflows, as the surface area and volume of the lake changed during the study

  1. Review Article: Potential geomorphic consequences of a future great (Mw = 8.0+) Alpine Fault earthquake, South Island, New Zealand

    NASA Astrophysics Data System (ADS)

    Robinson, T. R.; Davies, T. R. H.

    2013-09-01

    The Alpine Fault in New Zealand's South Island has not sustained a large magnitude earthquake since ca. AD 1717. The time since this rupture is close to the average inferred recurrence interval of the fault (~300 yr). The Alpine Fault is therefore expected to generate a large magnitude earthquake in the near future. Previous ruptures of this fault are inferred to have generated Mw = 8.0 or greater earthquakes and to have resulted in, amongst other geomorphic hazards, large-scale landslides and landslide dams throughout the Southern Alps. There is currently 85% probability that the Alpine Fault will cause a Mw = 8.0+ earthquake within the next 100 yr. While the seismic hazard is fairly well understood, that of the consequential geomorphic activity is less well studied, and these consequences are explored herein. They are expected to include landsliding, landslide damming, dam-break flooding, debris flows, river aggradation, liquefaction, and landslide-generated lake/fiord tsunami. Using evidence from previous events within New Zealand as well as analogous international examples, we develop first-order estimates of the likely magnitude and possible locations of the geomorphic effects associated with earthquakes. Landsliding is expected to affect an area > 30 000 km2 and involve > 1billion m3 of material. Some tens of landslide dams are expected to occur in narrow, steep-sided gorges in the affected region. Debris flows will be generated in the first long-duration rainfall after the earthquake and will continue to occur for several years as rainfall (re)mobilises landslide material. In total more than 1000 debris flows are likely to be generated at some time after the earthquake. Aggradation of up to 3 m will cover an area > 125 km2 and is likely to occur on many West Coast alluvial fans and floodplains. The impact of these effects will be felt across the entire South Island and is likely to continue for several decades.

  2. Micro Radiocarbon Dating - Applications and challenges in Alpine glaciology

    NASA Astrophysics Data System (ADS)

    Hoffmann, Helene; Bohleber, Pascal; Wagenbach, Dietmar

    2015-04-01

    The interpretation of proxy records from ice cores obtained at cold small scale Alpine glaciers is hampered first and foremost because of challenges in obtaining a reliable age scale, especially for highly thinned basal ice. Where conventional stratigraphic dating methods fail, either due to complex flow dynamics or missing layering, radiocarbon measurements of organic impurities are up to now the only option to retrieve absolute age markers. Supplementing stratigraphic records, age of basal ice itself can provide valuable information on paleoclimatic conditions, e.g. related to the onset of formation of the respective ice body. In this respect, potential targets are basal sections of Alpine ice cores and small isolated ice patches or ice caves. Organic material in ice can be separated mainly by size into DOC (Dissolved Organic Carbon) and POC (Particulate Organic Carbon). Here we focus on radiocarbon dating of the POC fraction, because the DOC fraction is known to be biased by in situ production at high Alpine sites. Concentrations of POC in high Alpine ice can be very low, ranging from about 10 µgC per kg ice to 50 µgC per kg ice. This becomes an immediate challenge when sampling ice cores, where available masses for dating are typically in the order of a few hundred grams of ice. After developing an unique sample preparation system we managed to reduce the process blank reproducibly below one microgram carbon, independent of other sample characteristics. Utilizing a gas ion source at the Accelerator Mass Spectrometer MICADAS at the Klaus-Tschira-Lab in Mannheim (Germany) we are now able to reliably date samples with concentrations as low as 10 µg carbon. Accordingly, this approach becomes applicable for high Alpine ice samples. Here we present first results from POC radiocarbon dating of Alpine ice cores along with selected basal ice samples from smaller ice caps and cave ice in order to obtain a broader picture regarding age ranges of Alpine ice bodies. For

  3. 6. Photocopy, photographer unknown, c. 193641 ALTERATIONS TO SOUTHWEST CORNER ...

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

    6. Photocopy, photographer unknown, c. 1936-41 ALTERATIONS TO SOUTHWEST CORNER OF ROOF, LOOKING EAST - White Deer Lake Camp, Beaver Cabin, Cyrus H. McCormick Experimental Forest, Champion, Marquette County, MI

  4. The impact of stocking on the genetic integrity of Arctic charr (Salvelinus) populations from the Alpine region.

    PubMed

    Englbrecht, Claudia C; Schliewen, Ulrich; Tautz, Diethard

    2002-06-01

    There is a long tradition of artificially stocking lakes and rivers with fish in the hope to increase the quality and amount of fish that can be harvested. The animals used for stocking often originate in distant hatcheries or hatcheries that breed fish from remote regions. This stocking practice could have effects on the genetic integrity of resident populations. We have analysed here a case of the influence of stocking on Alpine populations of the Arctic charr (usually included into Salvelinus alpinus, but revised to Salvelinus umbla Kottelat 1997) within a unique geographical and historical setting. The Königssee in the Bavarian Alps (Berchtesgaden) was heavily stocked several times during the last century. However, a sample of the ancestral Königssee population still exists in the Grünsee, which lies close to Königssee, but 1000 m higher. To trace the influence of stocking in Königssee we have analysed more than 300 individuals from 10 lake populations, including the source populations of the fish used for stocking. From these we have sequenced a part of the mitochodrial control region and have typed them at six microsatellite loci. The differential distribution of haplotypes, as well as assignment tests, show that the influence of stocking on the genetic integrity of the Königssee population has been negligible. However, our data reveal that in another lake included in our study (Starnberger See), the ancestral population was apparently replaced completely by the populations used for stocking. The major difference between the lakes is the relative preservation of ecological integrity. Königssee was ecologically stable in the past, whereas Starnberger See was heavily polluted at one point, with charr approaching extinction. Interestingly, in a lake neighbouring Starnberger See, the Ammersee, which was also subject to strong pollution but not stocked, the ancestral population has recovered. Our data suggest that the practice of artificial stocking should

  5. An invasion record for the swimbladder nematode Anguillicoloides crassus in European eel Anguilla anguilla in a deep warm-monomictic [corrected] lake, from invasion to steady state.

    PubMed

    Bernies, D; Brinker, A; Daugschies, A

    2011-09-01

    This study is the first account of the establishment and development of the neozoic nematode parasite Anguillicoloides crassus in its host, the European eel Anguilla anguilla, in a deep, warm-monomictic [corrected] lake. A 21 year study of A. crassus took place in Upper Lake Constance (ULC), Europe's second largest pre-alpine lake. The study included two extensive surveys, one in 1991 during the initial parasite invasion phase and the second in 2006 when the infection was well established. The subtropical swimbladder nematode A. crassus was first recorded in A. anguilla in ULC in 1989. Prevalence reached 60% in 1992 and remained at this level until 2007. In 2008, prevalence decreased to 48%. Infection intensity peaked in 1993 at a mean value of 16 adult parasites per host fish. Around 90% of all A. anguilla examined displayed swimbladder lesions, with a significant trend to increasing severity over time. Moreover, heavy swimbladder lesions were seen in c. 10% of A. anguilla ready to migrate to their spawning habitat. Both ruffe Gymnocephalus cernuus and sunfish Lepomis gibbosus serve as paratenic hosts for A. crassus in ULC. Gymnocephalus cernuus seems to be the main vector, and infection is especially frequent in spring possibly caused by reduced immune system efficacy of G. cernuus during winter. In 1991, hypochromic anaemia was prevalent in ULC A. anguilla acutely infected with A. crassus, whereas in 2006 blood values were indicative of chronic infection. The growth and survival rates of A. anguilla during their continental phase were not noticeably altered in infected fish, but damage to the swimbladder probably impairs migration potential and thus the subsequent breeding success of the oceanic phase. PMID:21884109

  6. Soil water dynamics and evapotranspiration in alpine ecosystems in the NE of Qinghai-Tibet Plateau, China

    NASA Astrophysics Data System (ADS)

    Li, Xiao-Yan; Zhang, Si-Yi; Ma, Yu-Jun

    2015-04-01

    Interactions between surface energy flux, evapotranspiration and soil water were poorly understood in the alpine ecosystems in the Qinghai-Tibet Plateau, which is a sensitive and vulnerable region to global climate change. For the first time, we continuously measured surface energy flux and soil water content (SWC) and estimated ET using bowen ratio energy balance method in the Qinghai Lake watershed, located in the northeast of Qinghai-Tibet Plateau between 2012 and 2013. The three ecosystems were Kobresia meadow (KMd.), Potentilla fruticosa shrub (PFSh.) and Achnatherum splendens steppe (ASSt.). Results indicated that there was a good negative correlation between ecosystem Bowen ratios and SWC in the growing season for the three ecosystems. Annual ET at KMd. and PFSh. was 16% and 3% less than local annual precipitation, while that at ASSt. was 26% larger than annual precipitation. Average annual ET was 507.9, 493.2 and 413.7 mm at PFSh., KMd. and ASSt., respectively. Fluctuations of daily ET at alpine ecosystems were primarily controlled by solar radiation, especially in the growing season, whereas, at ASSt. where precipitation and SWC was limited, ET was also controlled by water supply.

  7. Acid neutralizing processes in an alpine watershed front range, Colorado, U.S.A.-1: Buffering capacity of dissolved organic carbon in soil solutions

    USGS Publications Warehouse

    Iggy, Litaor M.; Thurman, E.M.

    1988-01-01

    Soil interstitial waters in the Green Lakes Valley, Front Range, Colorado were studied to evaluate the capacity of the soil system to buffer acid deposition. In order to determine the contribution of humic substances to the buffering capacity of a given soil, dissolved organic carbon (DOC) and pH of the soil solutions were measured. The concentration of the organic anion, Ai-, derived from DOC at sample pH and the concentration of organic anion, Ax- at the equivalence point were calculated using carboxyl contents from isolated and purified humic material from soil solutions. Subtracting Ax- from Ai- yields the contribution of humic substances to the buffering capacity (Aequiv.-). Using this method, one can evaluate the relative contribution of inorganic and organic constituents to the acid neutralizing capacity (ANC) of the soil solutions. The relative contribution of organic acids to the overall ANC was found to be extremely important in the alpine wetland (52%) and the forest-tundra ecotone (40%), and somewhat less important in the alpine tundra sites (20%). A failure to recognize the importance of organic acids in soil solutions to the ANC will result in erroneous estimates of the buffering capacity in the alpine environment of the Front Range, Colorado. ?? 1988.

  8. Integrating physical and chemical characteristics of lakes into the glacially influenced landscape of the Northern Cascade Mountains, Washington State, USA

    USGS Publications Warehouse

    Larson, Gary L.; Lomnicky, G.A.; Liss, W.J.; Deimling, E.

    1999-01-01

    A basic knowledge of the physical and chemical characteristics of lakes is needed by management to make informed decisions to protect water resources. In this study we investigated some of the physical and chemical characteristics of 58 lakes in alpine, subalpine, and forest vegetation zones in a natural area (North Cascades National Park Service Complex) between 1989 and 1993. The objectives of the study were to: (1) document the time of ice-out relative to lake elevation; (2) determine how a sharp climate gradient west and east of the hydrologic divide affected the time of ice-out for subalpine lakes; and (3) assess how lake water quality was associated with lake elevation, lake depth, and basin geology. As expected, lake ice-out times occurred earlier with decreasing elevation. East-slope subalpine lakes iced-out earlier than did west-slope subalpine lakes because the east slope of the study area was drier and warmer than the west slope. On average, the lakes were relatively cold, neutral in pH, and low in dissolved substances and concentrations of nitrogen and phosphorus. Although some shallow lakes (depth ,10 m) exhibited the highest alkalinities, conductivities, and concentrations of phosphorus and nitrogen, most shallow lakes exhibited low values for these variables that were comparable to values observed in deep lakes. Geology did not play a major role in segregating the lakes based on water quality. Overall, lake temperature, pH, alkalinity, conductivity, and concentrations of total phosphorus and total Kjeldahl N increased with decreasing elevation. These changes in water quality with decreasing elevation in this temperate mountainous region corresponded with warmer air temperatures and increased vegetation biomass, soil depth and maturity, and dissolved substances and nutrients.

  9. On siphons and sediments: A new model for draining active subglacial lakes in Antarctica informed with satellite radar and laser altimeter observations.

    NASA Astrophysics Data System (ADS)

    Carter, S. P.; Fricker, H. A.; Siegfried, M. R.

    2014-12-01

    With the advent of repeat-pass satellite-based surface altimetry over much of Antarctica, approximately 130 new subglacial lakes have been discovered entirely from observations of surface uplift and subsidence; these are commonly referred to as "active lakes". In contrast to the ~160 lakes detected by radar sounding ("RES" lakes), which are typically in mountains bedrock terrain near the ice divide and static with residence times spanning millenia, active lakes are typically located in fast flowing ice streams far from the divides, and have short residence times. To understand how water transfers through active lake systems we have developed a new model based on earlier theoretical work and informed by lake-volume estimates inferred from of ice surface displacements detected by satellite radar and laser altimetry. We find that although the overall pattern of filling and drainage is similar to that for ice dammed lakes in alpine regions via channels thermally eroded into the ice that then creeps shut as water pressure declines, Antarctic lake drainage is better simulated by invoking a channel mechanically eroded into the underlying sediment. The necessity of an erodable deformable substrate to explain lake drainage suggests that the distribution of active lakes is an indicator for the presence of sediment. Furthermore the process of lake drainage appears quite sensitive to the composion and strength of the underlying till. We explore these possibilities by testing the model on subglacial lakes in both East and West Antarctica, including Recovery Glacier and MacAyeal Ice stream.

  10. Inverse distributed hydrological modelling of alpine catchments

    NASA Astrophysics Data System (ADS)

    Kunstmann, H.; Krause, J.; Mayr, S.

    2005-12-01

    Even in physically based distributed hydrological models, various remaining parameters must be estimated for each sub-catchment. This can involve tremendous effort, especially when the number of sub-catchments is large and the applied hydrological model is computationally expensive. Automatic parameter estimation tools can significantly facilitate the calibration process. Hence, we combined the nonlinear parameter estimation tool PEST with the distributed hydrological model WaSiM. PEST is based on the Gauss-Marquardt-Levenberg method, a gradient-based nonlinear parameter estimation algorithm. WaSiM is a fully distributed hydrological model using physically based algorithms for most of the process descriptions. WaSiM was applied to the alpine/prealpine Ammer River catchment (southern Germany, 710 km2) in a 100×100 m2 horizontal resolution. The catchment is heterogeneous in terms of geology, pedology and land use and shows a complex orography (the difference of elevation is around 1600 m). Using the developed PEST-WaSiM interface, the hydrological model was calibrated by comparing simulated and observed runoff at eight gauges for the hydrologic year 1997 and validated for the hydrologic year 1993. For each sub-catchment four parameters had to be calibrated: the recession constants of direct runoff and interflow, the drainage density, and the hydraulic conductivity of the uppermost aquifer. Additionally, five snowmelt specific parameters were adjusted for the entire catchment. Altogether, 37 parameters had to be calibrated. Additional a priori information (e.g. from flood hydrograph analysis) narrowed the parameter space of the solutions and improved the non-uniqueness of the fitted values. A reasonable quality of fit was achieved. Discrepancies between modelled and observed runoff were also due to the small number of meteorological stations and corresponding interpolation artefacts in the orographically complex terrain. A detailed covariance analysis was performed

  11. Inverse distributed hydrological modelling of Alpine catchments

    NASA Astrophysics Data System (ADS)

    Kunstmann, H.; Krause, J.; Mayr, S.

    2006-06-01

    Even in physically based distributed hydrological models, various remaining parameters must be estimated for each sub-catchment. This can involve tremendous effort, especially when the number of sub-catchments is large and the applied hydrological model is computationally expensive. Automatic parameter estimation tools can significantly facilitate the calibration process. Hence, we combined the nonlinear parameter estimation tool PEST with the distributed hydrological model WaSiM. PEST is based on the Gauss-Marquardt-Levenberg method, a gradient-based nonlinear parameter estimation algorithm. WaSiM is a fully distributed hydrological model using physically based algorithms for most of the process descriptions. WaSiM was applied to the alpine/prealpine Ammer River catchment (southern Germany, 710 km2 in a 100×100 m2 horizontal resolution. The catchment is heterogeneous in terms of geology, pedology and land use and shows a complex orography (the difference of elevation is around 1600 m). Using the developed PEST-WaSiM interface, the hydrological model was calibrated by comparing simulated and observed runoff at eight gauges for the hydrologic year 1997 and validated for the hydrologic year 1993. For each sub-catchment four parameters had to be calibrated: the recession constants of direct runoff and interflow, the drainage density, and the hydraulic conductivity of the uppermost aquifer. Additionally, five snowmelt specific parameters were adjusted for the entire catchment. Altogether, 37 parameters had to be calibrated. Additional a priori information (e.g. from flood hydrograph analysis) narrowed the parameter space of the solutions and improved the non-uniqueness of the fitted values. A reasonable quality of fit was achieved. Discrepancies between modelled and observed runoff were also due to the small number of meteorological stations and corresponding interpolation artefacts in the orographically complex terrain. Application of a 2-dimensional numerical

  12. Permafrost aggradation in recently deglaciated alpine environments

    NASA Astrophysics Data System (ADS)

    Leopold, Matthias; Dusik, Jana; Stocker-Waldhuber, Martin; Völkel, Jörg; Becht, Michael

    2015-04-01

    Permafrost degradation is of major interest in the present discussion about alpine climate change and natural hazard prevention. Glacial retreat since the Little Ice Age (LIA) is followed by destabilisation of the surrounding mountains due to melting permafrost in bedrock and sediments. Glacial retreat also exposes huge areas of lateral and ground moraines. Areas of formerly temperate glaciers experience colder temperatures only since their ice cover has melted and basal meltwater no longer heats the ground. With a huge pore volume in the sediment body, water supply during the melt season and large daily temperature variations in high mountains, distinct freeze and thaw processes start and generate periglacial forms like patterned ground in the direct glacier forefield. Those geomorphic features are precursors for possible permafrost aggradation in proglacial areas. The work presented is part of the joint project PROSA (High-resolution measurements of morphodynamics in rapidly changing PROglacial Systems of the Alps) that aims in the quantification of a sediment budget for the upper Kaunertal valley, Austrian Central Alps. In this sense and to find out about erosion causing prerequisites and processes, permafrost and ground ice occurrence, as well as sediment thickness is measured by i.a. application of geophysical measurements, multitemporal airborne and terrestrial LiDAR, as well as aerial photographs. In this case study we examine the spatial and temporal settings for permafrost aggradation in a recently deglaciated cirque, belonging to the catchment area of the Gepatschferner glacier using electric resistivity tomography (ERT) and basal temperature of the winterly snowcover (BTS) measurements to detect the state of the permafrost, multitemporal aerial photographs dating back to 1953 to reproduce recent deglaciation of the cirque and multitemporal airborne LiDAR data to gain information about surface elevation changes. The northeast facing cirque is situated in

  13. Global warming prolongs the thermal stratification of dimictic lake Mondsee.

    NASA Astrophysics Data System (ADS)

    Blatterer, Hubert; Luger, Martin

    2013-04-01

    The pre-alpine Lake Mondsee is situated at the northern margin of the European Alps (47° 49´N, 13° 24´E) in the Salzkammergut lake district of Upper Austria at a sea level of 481 m. The lake has a surface area of 14,21 km² and a maximum water depth of 68 m (volume is 500 Mio m³ and theoretical water retention time is 1,8 years). Sediment samples confirm oligotrophic conditions as historical reference status of the lake. From 1970 to 1985 the lake suffered from severe eutrophication leading to cyanobacterial blooms (Planctothrix rubescens). Reduction of nutrient load in the course of improved sewage treatment resulted in re-oligotrophication from 1985 to about 2000. Currently, lake Mondsee is assessed mesotrophic and the biological quality elements "phytoplankton" and "macrophytes" classify the lake in the "moderate ecological status". According to the Water Framework Directive, a key initiative throughout the EU, the aim is to improve water quality and reach the "good ecological status". Temperature data of the Lake have been measured since the 30ies of the last century in varying intervals. In the present study (1991 - 2009) water temperature measured at the deepest point of the lake shows an increase in average surface temperature (0 - 5 m) of about 2 °C over the last two decades. The increase is less pronounced in deeper water layers and almost not visible below 15 m depth. Due to global change and rising temperatures stratification is starting earlier in the season and is prolonged from formerly end of November to the middle or even end of December. Thus, between 1999 and 2011 in several years the stratification period was extended for 5 weeks. During stratification oxygen depletion occurs in the depth of lakes and prolonged stratification results in increased areas of oxygen depletion. The oxygen concentration controls the phosphorus release of lake sediments. Therefore prolonged stratification results in increased internal phosphorus load of the lake

  14. An investigation of historical lake-atmosphere interactions in the Great Lakes Basin

    NASA Astrophysics Data System (ADS)

    Holman, Kathleen Danielle

    The Laurentian Great Lakes are a tremendous freshwater resource, holding approximately 20% of the world's unfrozen freshwater. With a combined surface area of 244,000 km2, the Great Lakes are constantly interacting with the overlying atmosphere through fluxes of heat, moisture, and momentum. In the current study, we explore interactions between the Great Lakes and overlying atmosphere using a combination of observational and modeling tools. Results based on historical observations indicate that over-lake precipitation from the Lake Superior watershed is associated with transient Rossby waves during each month of the year. Further analysis indicates the origin and path of these waves change with the background flow. During summer and early fall, the Pacific jet is relatively sharp and acts as a waveguide, such that Rossby wave trains traversing the Great Lakes region do not follow a great-circle path. While the atmosphere primarily dictates hydrology in the Great Lakes basin, each of the Great Lakes feeds back on the overlying atmosphere, ultimately influencing the local and regional climate. Historical observational and modeling studies support this claim; however, a consistent, long-term analysis of the impacts of the Great Lakes on climate has yet to be executed. In the current analysis, the influence of the Great Lakes on climate is assessed by comparing two decade-long regional climate simulations, with the lakes present or replaced by woodland. Model results indicate the Great Lakes dampen seasonal and daily surface air temperature ranges, alter the strength and track of synoptic systems, and modify atmospheric stability. Additional analysis based on output from the regional climate model indicates that seasonal fluctuations in atmospheric stability over Lake Superior influence the ratio of over-lake to over-land precipitation. Since the current operational technique used to estimate over-lake precipitation does not account for variations in atmospheric

  15. Alpine Skiing: Special Olympics Sports Skills Instructional Program.

    ERIC Educational Resources Information Center

    Joseph P. Kennedy, Jr. Foundation, Washington, DC.

    The first of five guides in the Sports Skills Instructional Program focuses on teaching alpine skiing to mentally retarded students. Each unit contains the following elements: overview, long-term goal, short-term objectives, modifications and adaptations, sports skill assessment, teaching skill, skill sequence, task analysis, teaching suggestions,…

  16. Efficiency of Energy Utilization by Lactating Alpine Goats

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Thirty-six lactating Alpine does (50.5 ± 1.2 kg BW) were used to determine the effect of stage of lactation on energy utilization. Twelve does were assigned for measurement periods in early, mid-, and late lactation (28-35, 91-98, and 189 to 196 d of lactation). For six does of each group, after m...

  17. Characterizing C-band backscattering from thermokarst lake ice on the Qinghai-Tibet Plateau

    NASA Astrophysics Data System (ADS)

    Tian, Bangsen; Li, Zhen; Engram, Melanie J.; Niu, Fujun; Tang, Panpan; Zou, Pengfei; Xu, Juan

    2015-06-01

    On the basis of weather observations and field measurements of lake ice, this study investigates multi-temporal C-band VV-polarized radar backscattering values from the thermokarst lakes and alpine meadow on the QTP during the period 2003-2010. In order to understand the scattering mechanism of lake ice, a scattering model is developed for lake ice that updates some assumptions adopted in previously developed models, including the roughness of the ice-water interface and the shape of vertically stacked centimeter-sized bubbles in the lake ice. We conclude the following: First, with a incidence angle range near 24°, the backscattering intensities of C-band VV-polarized ENVISAT-ASAR data exhibit a strong dependence on time, which is related to the processes of ice growth and decay on the QTP. Some unique backscattering characteristics of lake ice in this high-altitude region, as compared to those for high-latitude regions, are also discussed and documented in the paper. Secondly, the timing of lake ice-on in fall and ice-off in spring for this region can be identified in radar images by using a threshold of -12 dB for the backscatter intensity of the surrounding alpine meadow. Finally, the results of applying the scattering model indicate that surface scattering from the ice-water interface and volume scattering from gas bubbles embedded in the lake ice are the dominant scattering mechanisms for C-band VV polarized SAR and that the roughness of the ice-water interface and also bubble size are the most sensitive factors.

  18. Underflows in Lake Constance - Numerical Modeling, Instrumental Observations and Sediment Data

    NASA Astrophysics Data System (ADS)

    Eder, Magdalena; Wessels, Martin; Dare, Julian

    2014-05-01

    A torrential rain event in the western Alps in August 2005 caused high flood flows in the rivers Alpine Rhine and Bregenzer Ache which are the main tributaries into Lake Constance. The discharge of the Alpine Rhine reached 2200 m³/s, which is little below a centennial flood event. Discharge of the Bregenzer Ache was estimated to 1350 m³/s which statistically occurs every 100 yr but with a 1000 yr frequency in selected smaller tributaries. The high concentration of suspended solids in the fluvial water increased its density and created an underflow with considerable influence on the lake's hydrodynamics and water quality. Consequences within the lake were directly registered by a mooring (equipped with thermistor chain, sediment trap, current meter, oxygen sensor). Spatial data of the path and form of suspended matter cloud within the lake were gathered using echo sounder and probe measurements (turbidity, temperature, salinity). An underflow with a temperature of 14°C flew with 1.4 km/h some 20 km into the lake. Several days after the event, the fluvial sediments were detected as increased turbidity at the drinking water outtakes around the lake. Sediment cores recovered from the lake bottom show the distribution pattern of the sediments while sidescan data give a picture from proximal sediment structures originating from this event. Further, we modelled this underflow using the three dimensional hydrodynamic and water quality model ELCOM-CAEDYM. The suspended solids module of the model accounts for the impact of the sediment load on water density. Settling is considered using Stokes Law, and resuspension can also be included. The simulation of the August 2005 flood event and comparison with measured data impressively showed the ability to reproduce the most important effects of the flood flow on the lake. Comparative simulations with and without consideration of the coriolis effect indicate an influence of the coriolis force on the flow path of the density

  19. Caddisflies (Insecta: Trichoptera) of fringing wetlands of the Laurentian Great Lakes

    USGS Publications Warehouse

    Armitage, Brian J.; Hudson, Patrick L.; Wilcox, Douglas A.

    2001-01-01

    Fringing wetlands of the Laurentian Great Lakes are subject to natural processes, such as water-level fluctuation and wave-induced erosion, and to human alterations. In order to evaluate the quality of these wetlands over space and time, biological communities are often examined. This paper reports on the use of adult caddisflies to evaluate fringing wetlands of Lake Huron, Lake Michigan, and Lake Superior.

  20. Model Assessment of Permafrost Development for a Large Alpine Catchment

    NASA Astrophysics Data System (ADS)

    Voelksch, I.; Lehning, M.

    2005-12-01

    The extremely hot summer of 2003 saw increased rockfall and slope instability problems in the European Alps. This is generally attributed to permafrost thawing. Therefore, the development of permafrost in steep Alpine terrain under the observed warming trend needs to be investigated. We use ALPINE3D, a detailed model of Alpine surface processes to assess permafrost occurrence under the current climate and to predict an expected change under the warming scenario that future summers will be on average as the summer 2003. The ALPINE3D modules consist of a radiation balance model using a view factor approach and include short-wave scattering and long-wave emission from terrain and tall vegetation. The processes in the atmosphere are coupled to a distributed one-dimensional model of vegetation, snow and soil (SNOWPACK) using the assumption that lateral exchange is small in these media. Snow and soil processes are treated in much detail with adaptive multi-layer finite elements. The model modules can be run in a parallel (distributed) mode using a GRID infrastructure to allow such computationally demanding tasks. The application of ALPINE3D to the Cordevole river basin in the northern Italian Dolomites has been based on weather station data from seven locations in the area. A spatial resolution of 200 m is used for the simulation, which covers approximately 900 square kilometers. Typically, mass and energy exchange processes for 20 soil layers and up to 30 snow layers are calculated with an hourly time step and 15 years of data. In the steep terrain of the southern Alps, only a small area fraction has permafrost. Permafrost disappears almost completely under the warming scenario, which is achieved by simulating repeatedly the 2003 year.

  1. Stable isotopes in alpine precipitation as tracers of atmospheric deposition

    NASA Astrophysics Data System (ADS)

    Wasiuta, V. L.; Lafreniere, M. J.; Kyser, T. K.; Norman, A. L.; Mayer, B.; Wieser, M.

    2010-12-01

    Alpine ecosystems, which are generally nutrient poor and exist under extreme climatic conditions, are particularly sensitive to environmental and climatic stressors. Studies in the USA Rocky Mountains and European Alps have shown that alpine terrestrial and aquatic ecosystems are particularly sensitive to enhanced deposition of reactive nitrogen and can show ecologically destructive responses at relatively low levels of nitrogen deposition. However, there is no base line for atmospheric deposition of natural and anthropogenic contaminants in the Canadian alpine. Preliminary results of isotopic and chemical analyses of precipitation from an elevational transect on a glaciated alpine site in the Canadian Rockies are presented. Precipitation accumulating from early autumn through to spring (2008/2009 and 2009/2010) was sampled by means of seasonal snow cover on alpine glaciers. Summer precipitation was sampled through July and August 2010 using bulk collectors installed at the sites of winter sampling. The isotope ratios of dissolved sulphate (δ34S, δ18O), nitrogen (δ15N, δ18O), as well as precipitation (δ2H, δ18O) are utilized in addition to major ion concentrations and trace metal concentrations. Results from 2008/2009 snowpack samples indicate a strong seasonal trend in sulphate (SO42-) and nitrogen (NO3-) deposition which is consistent across the altitudinal transect. Snow horizons representing early autumn and spring precipitation show higher SO42- and NO3- concentrations in contrast to lower concentrations in winter horizons. The aforementioned suite of isotopic and chemical analyses are used to investigate the variability in dominant geographic source regions for atmospheric SO42- and NO3- (local, regional, or long range transported contaminants), as well as to identify contributions from the major biogeochemical source types (e.g. hydrocarbon combustion, lithogenic dust, agricultural emissions).

  2. Damaged beyond repair? Characterising the damage zone of a fault late in its interseismic cycle, the Alpine Fault, New Zealand

    NASA Astrophysics Data System (ADS)

    Williams, Jack N.; Toy, Virginia G.; Massiot, Cécile; McNamara, David D.; Wang, Ting

    2016-09-01

    X-ray computed tomography (CT) scans of drill-core, recovered from the first phase of the Deep Fault Drilling Project (DFDP-1) through New Zealand's Alpine Fault, provide an excellent opportunity to study the damage zone of a plate-bounding continental scale fault, late in its interseismic cycle. Documentation of the intermediate-macro scale damage zone structures observed in the CT images show that there is no increase in the density of these structures towards the fault's principal slip zones (PSZs), at least within the interval sampled, which is 30 m above and below the PSZs. This is in agreement with independent analysis using borehole televiewer data. Instead, we conclude the density of damage zone structures to correspond to lithology. We find that 72% of fractures are fully healed, by a combination of clays, calcite and quartz, with an additional 24% partially healed. This fracture healing is consistent with the Alpine Fault's late interseismic state, and the fact that the interval of damage zone sampled coincides with an alteration zone, an interval of extensive fluid-rock interaction. These fractures do not impose a reduction of P-wave velocity, as measured by wireline methods. Outside the alteration zone there is indirect evidence of less extensive fracture healing.

  3. The precipitation response to the desiccation of Lake Chad

    SciTech Connect

    Lauwaet D.; VanWeverberg K.; vanLipzig, N. P. M., Weverberg, K. V., Ridderb, K. D., and Goyens, C.

    2012-04-01

    Located in the semi-arid African Sahel, Lake Chad has shrunk from a surface area of 25000 km2 in 1960 to about 1350 km2 due to a series of droughts and anthropogenic influences. The disappearance of such a large open-water body can be expected to have a noticeable effect on the meteorology in the surroundings of the lake. The impact could extend even further to the west as westward propagating convective systems pass Lake Chad in the rainfall season. This study examines the sensitivity of the regional hydrology and convective processes to the desiccation of the lake using a regional atmospheric model. Three Lake Chad scenarios are applied reflecting the situation in 1960, the current situation and a potential future scenario in which the lake and the surrounding wetlands have disappeared. The model simulations span the months July-September in 2006, which includes the rainfall season in the Lake Chad area. Total precipitation amounts and the components of the hydrological cycle are found to be hardly affected by the existence of the lake. A filled Lake Chad does, however, increase the precipitation at the east side of the lake. The model results indicate that the boundary layer moisture and temperature are significantly altered downwind of the lake. By investigating a mesoscale convective system (MCS) case, this is found to affect the development and progress of the system. At first, the MCS is intensified by the more unstable boundary layer air but the persistence of the system is altered as the cold pool propagation becomes less effective. The proposed mechanism is able to explain the differences in the rainfall patterns nearby Lake Chad between the scenarios. This highlights the local sensitivity to the desiccation of Lake Chad whereas the large-scale atmospheric processes are not affected.

  4. Advance of alpine glaciers during final retreat of the Cordilleran ice sheet in the Finlay River area, northern British Columbia, Canada

    NASA Astrophysics Data System (ADS)

    Lakeman, Thomas R.; Clague, John J.; Menounos, Brian

    2008-03-01

    Sharp-crested moraines, up to 120 m high and 9 km beyond Little Ice Age glacier limits, record a late Pleistocene advance of alpine glaciers in the Finlay River area in northern British Columbia. The moraines are regional in extent and record climatic deterioration near the end of the last glaciation. Several lateral moraines are crosscut by meltwater channels that record downwasting of trunk valley ice of the northern Cordilleran ice sheet. Other lateral moraines merge with ice-stagnation deposits in trunk valleys. These relationships confirm the interaction of advancing alpine glaciers with the regionally decaying Cordilleran ice sheet and verify a late-glacial age for the moraines. Sediment cores were collected from eight lakes dammed by the moraines. Two tephras occur in basal sediments of five lakes, demonstrating that the moraines are the same age. Plant macrofossils from sediment cores provide a minimum limiting age of 10,550-10,250 cal yr BP (9230 ± 50 14C yr BP) for abandonment of the moraines. The advance that left the moraines may date to the Younger Dryas period. The Finlay moraines demonstrate that the timing and style of regional deglaciation was important in determining the magnitude of late-glacial glacier advances.

  5. Changes in the area of inland lakes in arid regions of central Asia during the past 30 years.

    PubMed

    Bai, Jie; Chen, Xi; Li, Junli; Yang, Liao; Fang, Hui

    2011-07-01

    Inland lakes are major surface water resource in arid regions of Central Asia. The area changes in these lakes have been proved to be the results of regional climate changes and recent human activities. This study aimed at investigating the area variations of the nine major lakes in Central Asia over the last 30 years. Firstly, multi-temporal Landsat imagery in 1975, 1990, 1999, and 2007 were used to delineate lake extents automatically based on Normalized Difference Water Index (NDWI) threshold segmentation, then lake area variations were detailed in three decades and the mechanism of these changes was analyzed with meteorological data and hydrological data. The results indicated that the total surface areas of these nine lakes had decreased from 91,402.06 km(2) to 46,049.23 km(2) during 1975-2007, accounting for 49.62% of their original area of 1975. Tail-end lakes in flat areas had shrunk dramatically as they were induced by both climate changes and human impacts, while alpine lakes remained relatively stable due to the small precipitation variations. With different water usage of river outlets, the variations of open lakes were more flexible than those of other two types. According to comprehensive analyses, different types of inland lakes presented different trends of area changes under the background of global warming effects in Central Asia, which showed that the increased human activities had broken the balance of water cycles in this region. PMID:20830516

  6. Longevity of Lake Superior lake trout

    USGS Publications Warehouse

    Schram, Stephen T.; Fabrizio, Mary C.

    1998-01-01

    The age structure of mature lake trout Salvelinus namaycush from the Wisconsin waters of Lake Superior increased following a population recovery that has taken place since the 1960s. As the population aged, it became apparent that scales were unreliable aging structures. Beginning in 1986, we examined both scale and sagittal otolith ages from tagged fish with a known period at liberty. We found large discrepancies in scale and sagittal otolith ages of mature fish, such that scale ages were biased low. We estimated lake trout living up to 42 years, which is greater than previously reported from Lake Superior. Investigators studying lake trout population dynamics in the Great Lakes should be aware that lake trout can live longer than previously thought.

  7. Linkage between Three Gorges Dam impacts and the dramatic recessions in China’s largest freshwater lake, Poyang Lake

    NASA Astrophysics Data System (ADS)

    Mei, Xuefei; Dai, Zhijun; Du, Jinzhou; Chen, Jiyu

    2015-12-01

    Despite comprising a small portion of the earth’s surface, lakes are vitally important for global ecosystem cycling. However, lake systems worldwide are extremely fragile, and many are shrinking due to changing climate and anthropogenic activities. Here, we show that Poyang Lake, the largest freshwater lake in China, has experienced a dramatic and prolonged recession, which began in late September of 2003. We further demonstrate that abnormally low levels appear during October, 28 days ahead of the normal initiation of the dry season, which greatly imperiled the lake’s wetland areas and function as an ecosystem for wintering waterbirds. An increase in the river-lake water level gradient induced by the Three Gorges Dam (TGD) altered the lake balance by inducing greater discharge into the Changjiang River, which is probably responsible for the current lake shrinkage. Occasional episodes of arid climate, as well as local sand mining, will aggravate the lake recession crisis. Although impacts of TGD on the Poyang Lake recession can be overruled by episodic extreme droughts, we argue that the average contributions of precipitation variation, human activities in the Poyang Lake catchment and TGD regulation to the Poyang Lake recession can be quantified as 39.1%, 4.6% and 56.3%, respectively.

  8. Linkage between Three Gorges Dam impacts and the dramatic recessions in China’s largest freshwater lake, Poyang Lake

    PubMed Central

    Mei, Xuefei; Dai, Zhijun; Du, Jinzhou; Chen, Jiyu

    2015-01-01

    Despite comprising a small portion of the earth’s surface, lakes are vitally important for global ecosystem cycling. However, lake systems worldwide are extremely fragile, and many are shrinking due to changing climate and anthropogenic activities. Here, we show that Poyang Lake, the largest freshwater lake in China, has experienced a dramatic and prolonged recession, which began in late September of 2003. We further demonstrate that abnormally low levels appear during October, 28 days ahead of the normal initiation of the dry season, which greatly imperiled the lake’s wetland areas and function as an ecosystem for wintering waterbirds. An increase in the river-lake water level gradient induced by the Three Gorges Dam (TGD) altered the lake balance by inducing greater discharge into the Changjiang River, which is probably responsible for the current lake shrinkage. Occasional episodes of arid climate, as well as local sand mining, will aggravate the lake recession crisis. Although impacts of TGD on the Poyang Lake recession can be overruled by episodic extreme droughts, we argue that the average contributions of precipitation variation, human activities in the Poyang Lake catchment and TGD regulation to the Poyang Lake recession can be quantified as 39.1%, 4.6% and 56.3%, respectively. PMID:26657816

  9. Lake Volta, Ghana

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This true-color image of Lake Volta in Ghana was acquired March 31, 2002 by the Moderate Resolution Imaging Spectroradiometer (MODIS). Lake Volta is one of the world's largest artificially created lakes. Lake Volta is actually a reservoir formed from the damming of the Volta River, and extends 250 miles north of the Akosombo Dam. The lake covers an area of 8,482 square km. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

  10. Effects of the 1980 eruption of Mount St Helens on the limnological characteristics of selected lakes in western Washington

    USGS Publications Warehouse

    Embrey, S.S.; Dion, N.P.

    1988-01-01

    The 1980 eruption of Mount St. Helens provided the opportunity to study its effect on the physical, chemical, and biological characteristics of lakes near the volcano, and to describe two newly created lakes. Concentrations of dissolved solids and organic carbon, measured in June 1980, had increased from 2 to 30 times those observed in the 1970 's in Spirit, St. Helens, and Venus Lakes. Water in the lakes was altered from preeruption calcium-bicarbonate types to calcium-sulfate, calcium sulfate-chloride, or lake surface, as in St. Helens Lake; transparency in Venus Lake had improved to a depth of 24 ft by 1982. Spirit Lake was anoxic into fall 1980, but had reaerated to 5.2 mg/L of dissolved oxygen by May 1981. Phytoplankton communities in existing lakes in the blast zone in 1980 were primarily green and bluegreen algae; diatoms were sparse until summer 1982. Small numbers of zooplankton in Spirit, St. Helens, and Venus Lakes, compared to numbers in Walupt and Fawn Lakes, may indicate some post-eruption mortality. Rotifers were absent from lakes in the blast zone, but by 1981 were observed in all the lakes. The recovery of the physical, chemical, and biological characteristics of the lakes will depend on stabilization of the surrounding environment and biological processes within each lake. Excluding Spirit Lake, it is estimated that St. Helens Lake would be the slowest to recover and Venus Lake the fastest. (USGS)

  11. DNA ALTERATIONS

    EPA Science Inventory

    The exposure of an organism to genotoxic chemicals may induce a cascade of genetic events. nitially, structural alterations to DNA are formed. ext, the DNA damage is processed and subsequently expressed in mutant gene products. inally, diseases result from the genetic damage. he ...

  12. Mapping lake level changes using ICESat/GLAS satellite laser altimetry data: a case study in arid regions of central Asia

    NASA Astrophysics Data System (ADS)

    Li, JunLi; Fang, Hui; Yang, Liao

    2011-12-01

    Lakes in arid regions of Central Asia act as essential components of regional water cycles, providing sparse but valuable water resource for the fragile ecological environments and human lives. Lakes in Central Asia are sensitive to climate change and human activities, and great changes have been found since 1960s. Mapping and monitoring these inland lakes would improve our understanding of mechanism of lake dynamics and climatic impacts. ICESat/GLAS satellite laser altimetry provides an efficient tool of continuously measuring lake levels in these poorly surveyed remote areas. An automated mapping scheme of lake level changes is developed based on GLAS altimetry products, and the spatial and temporal characteristics of 9 typical lakes in Central Asia are analyzed to validate the level accuracies. The results show that ICESat/GLAS has a good performance of lake level monitoring, whose patterns of level changes are the same as those of field observation, and the max differences between GLAS and field data is 3cm. Based on the results, it is obvious that alpine lakes are increasing greatly in lake levels during 2003-2009 due to climate change, while open lakes with dams and plain endorheic lakes decrease dramatically in water levels due to human activities, which reveals the overexploitation of water resource in Central Asia.

  13. 125 years of glacier survey of the Austrian Alpine Club: results and future challenges

    NASA Astrophysics Data System (ADS)

    Fischer, Andrea

    2016-04-01

    One of the aims of the German and Austrian Alpine Club was the scientific investigation of the Alps. In 1891, several years after Swiss initiatives, Richter put out a call to contribute to regular glacier length surveys in the Eastern Alps. Since then more than 100 glaciers have been surveyed on a first biannual and later annual basis. The database includes measured data showing a general glacier retreat since 1891, with two periods of glacier advances in the 1920s and 1980s. Less well known are the sketches and reports which illustrate, for instance, changes in surface texture. The interpretation of length change data requires a larger sample of data for a reasonable interpretation on a regional scale. Nearly every time series in the long history of investigation includes gaps, e.g. in cases of problematic snout positions on steep rock walls or in lakes, or of debris-covered tongues. Current climate change adds the problem of glaciers splitting up into several smaller glaciers which behave differently. Several basic questions need to be addressed to arrive at a most accurate prolongated time series: How should measurements on disintegrating or debris-covered (and thus more or less stagnating) glaciers be documented, and how can we homogenize length change time series? Despite of uncertainties, length change data are amongst the longest available records, bridging the gap to moraine datings of the early holocene.

  14. Lake-level variability and water availability in the Great Lakes

    USGS Publications Warehouse

    Wilcox, Douglas A.; Thompson, Todd A.; Booth, Robert K.; Nicholas, J.R.

    2007-01-01

    years ago. Within that record is a quasi-periodic rise and fall of about 160 ? 40 years in duration and a shorter fluctuation of 32 ? 6 years that is superimposed on the 160-year fluctuation. Recorded lake-level history from 1860 to the present falls within the longer-term pattern and appears to be a single 160-year quasi-periodic fluctuation. Independent investigations of past climate change in the basin over the long-term period of record confirm that most of these changes in lake level were responses to climatically driven changes in water balance, including lake-level highstands commonly associated with cooler climatic conditions and lows with warm climate periods. The mechanisms underlying these large hydroclimatic anomalies are not clear, but they may be related to internal dynamics of the ocean-atmosphere system or dynamical responses of the ocean-atmosphere system to variability in solar radiation or volcanic activity. The large capacities of the Great Lakes allow them to store great volumes of water. As calculated at chart datum, Lake Superior stores more water (2,900 mi3) than all the other lakes combined (2,539 mi3). Lake Michigan's storage is 1,180 mi3; Lake Huron's, 850 mi3; Lake Ontario's, 393 mi3; and Lake Erie's, 116 mi3. Seasonal lake-level changes alter storage by as much as 6 mi3 in Lake Superior and as little as 2.1 mi3 in Lake Erie. The extreme high and low lake levels measured in recorded lake-level history have altered storage by as much as 31 mi3 in Lake Michigan-Huron and as little as 9 mi3 in Lake Ontario. Diversions of water into and out of the lakes are very small compared to the total volume of water stored in the lakes. The water level of Lake Superior has been regulated since about 1914 and levels of Lake Ontario since about 1960. The range of Lake Superior water-level fluctuations and storage has not been altered greatly by regulation. However, fluctuations on Lake Ontario have been reduced from 6.6 ft preregulation

  15. Physical properties of surface outcrop cataclastic fault rocks, Alpine Fault, New Zealand

    NASA Astrophysics Data System (ADS)

    Boulton, C.; Carpenter, B. M.; Toy, V.; Marone, C.

    2012-01-01

    We present a unified analysis of physical properties of cataclastic fault rocks collected from surface exposures of the central Alpine Fault at Gaunt Creek and Waikukupa River, New Zealand. Friction experiments on fault gouge and intact samples of cataclasite were conducted at 30-33 MPa effective normal stress (σn') using a double-direct shear configuration and controlled pore fluid pressure in a true triaxial pressure vessel. Samples from a scarp outcrop on the southwest bank of Gaunt Creek display (1) an increase in fault normal permeability (k = 7.45 × 10-20 m2 to k = 1.15 × 10-16 m2), (2) a transition from frictionally weak (μ = 0.44) fault gouge to frictionally strong (μ = 0.50-0.55) cataclasite, (3) a change in friction rate dependence (a-b) from solely velocity strengthening, to velocity strengthening and weakening, and (4) an increase in the rate of frictional healing with increasing distance from the footwall fluvioglacial gravels contact. At Gaunt Creek, alteration of the primary clay minerals chlorite and illite/muscovite to smectite, kaolinite, and goethite accompanies an increase in friction coefficient (μ = 0.31 to μ = 0.44) and fault-perpendicular permeability (k = 3.10 × 10-20 m2 to k = 7.45 × 10-20 m2). Comminution of frictionally strong (μ = 0.51-0.57) cataclasites forms weaker (μ = 0.31-0.50) foliated cataclasites and fault gouges with behaviors associated with aseismic creep at low strain rates. Combined with published evidence of large magnitude (Mw ˜ 8) surface ruptures on the Alpine Fault, petrological observations indicate that shear failure involved frictional sliding within previously formed, velocity-strengthening fault gouge.

  16. Lignin decomposition along an Alpine elevation gradient in relation to physicochemical and soil microbial parameters.

    PubMed

    Duboc, Olivier; Dignac, Marie-France; Djukic, Ika; Zehetner, Franz; Gerzabek, Martin H; Rumpel, Cornelia

    2014-07-01

    Lignin is an aromatic plant compound that decomposes more slowly than other organic matter compounds; however, it was recently shown that lignin could decompose as fast as litter bulk carbon in minerals soils. In alpine Histosols, where organic matter dynamics is largely unaffected by mineral constituents, lignin may be an important part of soil organic matter (SOM). These soils are expected to experience alterations in temperature and/or physicochemical parameters as a result of global climate change. The effect of these changes on lignin dynamics remains to be examined and the importance of lignin as SOM compound in these soils evaluated. Here, we investigated the decomposition of individual lignin phenols of maize litter incubated for 2 years in-situ in Histosols on an Alpine elevation gradient (900, 1300, and 1900 m above sea level); to this end, we used the cupric oxide oxidation method and determined the phenols' (13) C signature. Maize lignin decomposed faster than bulk maize carbon in the first year (86 vs. 78% decomposed); however, after the second year, lignin and bulk C decomposition did not differ significantly. Lignin mass loss did not correlate with soil temperature after the first year, and even correlated negatively at the end of the second year. Lignin mass loss also correlated negatively with the remaining maize N at the end of the second year, and we interpreted this result as a possible negative influence of nitrogen on lignin degradation, although other factors (notably the depletion of easily degradable carbon sources) may also have played a role at this stage of decomposition. Microbial community composition did not correlate with lignin mass loss, but it did so with the lignin degradation indicators (Ac/Al)s and S/V after 2 years of decomposition. Progressing substrate decomposition toward the final stages thus appears to be linked with microbial community differentiation. PMID:24323640

  17. Seasonal variability of surface runoff for different land-use types in alpine landscapes

    NASA Astrophysics Data System (ADS)

    Leitinger, G.; Tappeiner, U.; Newesely, Ch.; Obojes, N.; Tasser, E.

    2009-04-01

    Knowledge of surface runoff quantity for distinct hydrological units becomes increasingly important as many rainfall-runoff models use static surface runoff coefficients and therefore neglect eco-hydrological diversity. Especially in small-scale alpine catchments surface runoff and its contribution to mountain torrent runoff is frequently underestimated. Alpine ecosystems are faced with a rapid shift in vegetation patterns due to climate and also land-use change, which alters hydrological behavior in short timescales, even within a season. In a study in the Eastern Alps, Stubai Valley, Austria, surface runoff was investigated by using a rain simulator and accompanying soil water content and soil water tension measurements in different soil depths. Additionally, soil type, soil physical properties and phytomass were assessed. Analyzing more than 40 sprinkler experiments revealed significantly different surface runoff coefficients for different land-use / land-cover types. Moreover, managed areas revealed a clear seasonal variability of surface runoff. The results infer the necessity to consider intensity, duration and date of management when quantifying surface runoff. In other words, as surface runoff reaches the catchment outlet very quickly, water levels will raise much more than for very similar conditions at another date of the season. While almost no surface runoff occurred on abandoned areas, pastures showed high seasonal variability with surface runoff coefficients between 0% and 25%. The results are linked to land-cover type and soil physical properties, among which bulk density and resulting infiltration rates turned out to be most decisive. On pastures soil compaction by grazing cattle could increase stream flow dramatically. However, soil compaction in upper horizons (A-horizon, < 10cm soil depth) was reduced by freeze-and-thaw processes during the winter season. Thereby bulk density decreased and infiltration rates increased. The duration of this

  18. [Rate of microsuccessions: Structure and floristic richness recovery after sod transplantation in alpine plant communities].

    PubMed

    Kipkeev, A M; Cherednichenko, O V; Tekeev, D K; Onipchenko, V G

    2015-01-01

    Reciprocal transplantations of sod pieces have been conducted in alpine plant communities of the northwestern Caucasus. During 25 years, the changes in floristic richness and successional rates have been registered. Study objects were chosen to be. plant communities located along the toposequence from ridges to hollows with gradient of snow. cover thickness increase and vegetation period decrease, namely alpine lichen heath (ALH), Festuca varia grasslands (FVG), Geranium-Hedysarum meadows (GHM), and snow bed communities (SBC). The results of the study confirm the hypothesis about floristic richness of transplanted pieces to come closer to that of a background acceptor community. It is shown that during succession the variability reduces if sod pieces from different communities are transplanted into a common one. In particular, this is evident in case of SBC, where floristic richness of sod pieces transplanted from ALH and GHM has reduced noticeably. Also, it is evident from the results that the more different are donor and acceptor communities the higher is the rate of their changing. However, the assumption of higher succession rate in more productive communities has not been affirmed. On the opposite, communities with initially low productivity turned out to change faster than those with high productivity. It is found out that sod pieces transplanted to upper areas of the toposequence have had higher rate of alteration in comparison with those transplanted to lower areas. The reason behind this, as it may be suggested, is a longer growth season, which means a more prolonged period of high functional activity, and, accordingly, more time for the effects of competition, bringing seeds over, etc. In whole, the rate of succession decreases as the time from the moment of transplantation.increases, especially in communities with low productivity. PMID:26852571

  19. Long-term experimental manipulation of winter snow regime and summer temperature in arctic and alpine tundra

    USGS Publications Warehouse

    Walker, M.D.; Walker, D. A.; Welker, J.M.; Arft, A.M.; Bardsley, T.; Brooks, P.D.; Fahnestock, J.T.; Jones, M.H.; Losleben, M.; Parsons, A.N.; Seastedt, T.R.; Turner, P.L.

    1999-01-01

    Three 60 m long, 2.8 m high snowfences have been erected to study long-term effects of changing winter snow conditions on arctic and alpine tundra. This paper describes the experimental design and short-term effects. Open-top fiberglass warming chambers are placed along the experimental snow gradients and in controls areas outside the fences; each warming plot is paired with an unwarmed plot. The purpose of the experiment is to examine short- and long-term changes to the integrated physical-biological systems under simultaneous changes of winter snow regime and summer temperature, as part of the Long-Term Ecological Research network and the International Tundra Experiment. The sites were at Niwot Ridge, Colorado, a temperate high altitude site in the Colorado Rockies, and Toolik Lake, Alaska, a high-latitude site. Initial results indicate that although experimental designs are essentially identical at the arctic and alpine sites, experimental effects are different. The drift at Niwot Ridge lasts much longer than do the Toolik Lake drifts, so that the Niwot Ridge fence affects both summer and winter conditions, whereas the Toolik Lake fence affects primarily winter conditions. The temperature experiment also differs in effect between the sites. Although the average temperature increase at the two sites is similar (daily increase 1.5??C at Toolik and 1.9??C at Niwot Ridge), at Toolik Lake there is only minor diurnal variation, whereas at Niwot Ridge the daytime increases are extreme on sunny days (as much as 7-10??C), and minimum nighttime temperatures in the chambers are often slightly cooler than ambient (by about 1??C). The experimental drifts resulted in wintertime increases in temperature and CO2 flux. Temperatures under the deep drifts were much more consistent and warmer than in control areas, and at Niwot Ridge remained very close to 0??C all winter. These increased temperatures were likely responsible for observed increases in system carbon loss. Initial

  20. Historical profiles of PCB in dated sediment cores suggest recent lake contamination through the "halo effect".

    PubMed

    Naffrechoux, Emmanuel; Cottin, Nathalie; Pignol, Cécile; Arnaud, Fabien; Jenny, Jean-Philippe; Perga, Marie-Elodie

    2015-02-01

    We investigated the major sources of polychlorinated biphenyls (PCB) and interpreted the environmental fate processes of these persistent organic pollutants in the past and current PCB contamination of three large, urbanized, French peri-alpine lakes. Dated sediment cores were analyzed in order to reconstruct and compare the historical contamination in all three lakes. Stratigraphic changes of PCB contents and fluxes were considered as revealing the temporal dynamics of PCB deposition to the lakes and the distribution of the seven indicator congeners (further referred to as PCBi) as an indicator of the main contamination origin and pathway. Although located within a single PCB industrial production region, concentration profiles for the three lakes differed in timing, peak concentration magnitudes, and in the PCBi congeners compositions. PCBi fluxes to the sediment and the magnitude of the temporal changes were generally much lower in Lake Annecy (0.05-2 ng·cm(-2)·yr(-1)) as compared to Lakes Geneva (0.05-5 ng·cm(-2)·yr(-1)) and Bourget (5-290 ng·cm(-2)·yr(-1)). For all three lakes, the paramount contamination occurred in the early 1970s. In Lakes Annecy and Bourget, PCB fluxes have declined and plateaued at 0.5 and 8 ng·cm(-2)·yr(-1), respectively, since the early 1990s. In Lake Geneva, PCB fluxes have further decreased by the end of the XX(th) century and are now very low. For the most contaminated lake (Lake Bourget), the high PCBi flux (5-290 ng·cm(-2)·yr(-1)) and the predominance of heavy congeners for most of the time period are consistent with a huge local input to the lake. This still high rate of Lake Bourget is explained by transport of suspended solids from one of its affluents, polluted by an industrial point source. Intermediate historical levels and PCBi distribution over time for Lake Geneva suggest a mixed contamination (urban point sources and distant atmospheric transport), while atmospheric deposition to Lake Annecy explains its lowest

  1. Late Holocene Hydrologic Variability Reconstruction of the Coastal Southwestern United States Using Lake Sediments from Crystal Lake, CA

    NASA Astrophysics Data System (ADS)

    Palermo, J. A.; Kirby, M. E.; Hiner, C.; Leeper, R. J.

    2014-12-01

    This study aims to reconstruct a high resolution, late Holocene record of precipitation variability for the coastal southwestern United States region using sediment cores from Crystal Lake, CA. This region is especially susceptible to droughts and episodic floods, making it of particular importance to understand past hydrologic variability. Crystal Lake is a small, alpine landslide dammed lake in the Angeles National Forest of the San Gabriel Mountains. The lake is the only permanent, freshwater lake located in the range. It is hydrologically closed, meaning all lake level changes are controlled by changes in precipitation: evaporation. To reconstruct past hydrologic variability, two Livingston piston cores were taken 15 m apart in the depocenter of the lake in May 2014. A multi-proxy methodology was utilized including: magnetic susceptibility, total organic matter and total carbonate content, grain size, and bulk d13Corg of sediments. All analyses were conducted at 1 cm contiguous intervals except bulk d13Corg (at 2 cm). Seismic reflection profiles were also generated to examine the basin's stratigraphic features in the context of the individual sediment cores. A working age model was provided by multiple AMS 14C dates from discrete organic matter (i.e., seeds, charcoal). Results from this study are compared to preexisting records of late Holocene hydrologic variability from coastal, central, and southern California. Further, the forcing mechanisms that drive hydrologic change (wet vs. dry episodes) in Southern California, such as ocean-atmosphere interactions including El Niño Southern Oscillation or the Pacific Decadal Oscillation, are discussed.

  2. Late Holocene High Discharge and Erosion Events Inferred from Sediment Proxies and Catchment Geomorphology, Lake Vuoksjávrátje, NW Sweden

    NASA Astrophysics Data System (ADS)

    Berntsson, A.; Jansson, K. N.; Kylander, M. E.; De Vleeschouwer, F.; Bertrand, S.

    2014-12-01

    Alpine lakes in NW Sweden are highly sensitive to variations in catchment erosion and in precipitation. Previous studies aimed at reconstructing past summer temperatures have suggested that this sensitivity may influence chironomid species composition enough to cause bias in quantitative temperature reconstructions. In this study we have analysed lake sediments covering the last 5100 years from Lake Vuoksjávrátje in NW Sweden and catchment geomorphology with the aim to separate between different erosional regimes in the lake and its catchment and to identify sediment sources and processes behind sediment deposition in the lake basin. Methods include XRF core scanning, grain size analysis, chironomid analysis, TOC and C/N analysis and detailed mapping of geomorphology. From the integrated results we identify time intervals with increased catchment erosion, inferred to result from intense precipitation. Based on the combined proxy data it was concluded that a major flood event took place at the Vindelfjällen site c. 2800 cal BP, unique for the 5100-year long record. The chironomid species composition shows stronger influence from wetland surface erosion at c. 2800 cal BP and during the last c. 1000 years. By combining multi-proxy lake sediment analysis with study of catchment geomorphology it is possible to improve the understanding of Late Holocene hydro-climatic change and how it may influence Arctic alpine lakes.

  3. Phosphorus biogeochemistry in alpine ecosystems of the Northern Caucasus

    NASA Astrophysics Data System (ADS)

    Makarov, Mikhail; Vaganov, Ivan

    2010-05-01

    The study of phosphorus biogeochemistry in an alpine landscape of the Northern Caucasus has been spent in the Teberda Biosphere Reserve on the experimental plot with total area of 3.9 ha (150 m wide, 260 m long, altitude differences 100 m) and on the plots of long-term experiment on studying of nutrients application influence on alpine ecosystems located in the eastern slope of Mt. Malaya Khatipara. Results of studying of phosphorus concentrations and store in alpine soils and plant phytomass indicated differences for diverse alpine ecosystems along geochemical gradient. Although biological accumulation of phosphorus in the upper part of soil profiles was general characteristic of all ecosystems, it is shown that geochemical redistribution of phosphorus from eluvial to accumulative parts of a landscape is the main thing in the course of phosphorus and its labile compounds accumulation in soils of the alpine communities of accumulative habitats. In turn, biological accumulation of phosphorus in soils of different alpine ecosystems redistributes an element in a soil profile with different intensity depending on capacity of biological cycle. The biological factor causes also prevalence of organic compounds among of phosphorus migrating forms in modern soils and in a landscape. As inorganic (0.01-0.02 mg/L) as organic (up to 0.17 mg/L) phosphorus leaching in the eluvial soils was from 2 to 5 times lower compared with soils of accumulative positions in a landscape. Soil phosphorus fractionation on organic and inorganic compounds of different geochemical mobility and biological availability indicated differences of phosphorus state for diverse alpine ecosystems along the experimental plot. The minor proportion of 0.5 M NaHCO3 (pH 8.5) extractable labile organic and inorganic phosphates was general characteristic of all studied soils, although especially low proportion of labile phosphorus compounds was typical for lichen heath soil, while soils of snow-bed communities

  4. Geologic Map of Mount Mazama and Crater Lake Caldera, Oregon

    USGS Publications Warehouse

    Bacon, Charles R.

    2008-01-01

    Crater Lake partly fills one of the most spectacular calderas of the world, an 8-by-10-km basin more than 1 km deep formed by collapse of the volcano known as Mount Mazama (fig. 1) during a rapid series of explosive eruptions about 7,700 years ago. Having a maximum depth of 594 m, Crater Lake is the deepest lake in the United States. Crater Lake National Park, dedicated in 1902, encompasses 645 km2 of pristine forested and alpine terrain, including the lake itself, virtually all of Mount Mazama, and most of the area of the geologic map. The geology of the area was first described in detail by Diller and Patton (1902) and later by Williams (1942), whose vivid account led to international recognition of Crater Lake as the classic collapse caldera. Because of excellent preservation and access, Mount Mazama, Crater Lake caldera, and the deposits formed by the climactic eruption constitute a natural laboratory for study of volcanic and magmatic processes. For example, the climactic ejecta are renowned among volcanologists as evidence for systematic compositional zonation within a subterranean magma chamber. Mount Mazama's climactic eruption also is important as the source of the widespread Mazama ash, a useful Holocene stratigraphic marker throughout the Pacific Northwest, adjacent Canada, and offshore. A detailed bathymetric survey of the floor of Crater Lake in 2000 (Bacon and others, 2002) provides a unique record of postcaldera eruptions, the interplay between volcanism and filling of the lake, and sediment transport within this closed basin. Knowledge of the geology and eruptive history of the Mount Mazama edifice, greatly enhanced by the caldera wall exposures, gives exceptional insight into how large volcanoes of magmatic arcs grow and evolve. Lastly, the many smaller volcanoes of the High Cascades beyond the limits of Mount Mazama are a source of information on the flux of mantle-derived magma through the region. General principles of magmatic and eruptive

  5. Effects of experimentally modified soil temperatures and nutrient availability on growth and mycorrhization of Pinus cembra at the alpine treeline

    NASA Astrophysics Data System (ADS)

    Gruber, Andreas; Peintner, Ursula; Wieser, Gerhard; Oberhuber, Walter

    2015-04-01

    Soil temperature affects litter decomposition, nutrient uptake, root growth and respiration and it is suggested that soil temperature has direct impact on tree growth at the alpine treeline. We have evaluated the impact of experimentally modified soil temperatures and nutrient availability on growth and mycorrhization of Pinus cembra at the treeline in the Central Eastern Alps (c. 2150 m a.s.l., Tyrol, Austria). Soil temperature in the rooting zone of naturally grown c. 25 year old trees (n=6 trees per treatment) was altered by shading and heat-trapping using non-transparent and glasshouse foils mounted c. 20 cm above soil surface. Additional trees were selected for a nitrogen fertilisation treatment and as controls. During the study period, mean soil temperatures at 10 cm depth were reduced by c. 3°C at the cooled vs. warmed plots. Soil moisture was not influenced due to soil water transport along the slope. Results revealed that changed soil temperatures did not significantly affect tree growth, gas exchange, needle nutrient content and specific leaf area. We also found no significant difference in degree of mycorrhization or number of mycorrhized root tips between treatments. On the other hand, nitrogen fertilization and a reduction of interspecific root competition led to significantly raised radial stem growth. Results indicate that tree growth at the selected study area was not limited by soil temperature, while interspecific competition for nutrients among trees and low stature vegetation (dwarf shrubs, grasses) had significant impact. Therefore, we suggest that root competition with alpine grassland and dwarf-shrub communities will hamper temperature driven advance of alpine treeline in the course of climate warming. Acknowledgements This work was funded by the Austrian Science Fund (FWF Project No. P22836-B16, 'Growth response of Pinus cembra to experimentally modified soil temperatures at the treeline').

  6. Alpine exhumation of the central Cantabrian Mountains, Northwest Spain

    NASA Astrophysics Data System (ADS)

    Fillon, C.; Pedreira, D.; Beek, P. A.; Huismans, R. S.; Barbero, L.; Pulgar, J. A.

    2016-02-01

    The Cantabrian Mountains extend along the Atlantic coast of northern Spain and are known to have experienced an Alpine phase of deformation, reactivating well-expressed Variscan structures. They form the westward continuation of the Pyrenean range and were similarly uplifted consequently to the convergence between the Iberian and European plates. Nevertheless, due to the scarcity of syntectonic sediments and structural markers in a large outcrop of Variscan basement, little is known about the precise timing and amount of the Alpine exhumation phase in the Cantabrian Mountains. We present a new low-temperature thermochronology data set, composed of nine apatite fission track (AFT) and six zircon (U-Th)/He (ZHe) ages, sampled along structurally well-constrained N-S profiles through the central part of the Cantabrian Mountains and complemented by 3-D thermokinematic modeling. The occurrence of Eocene-Oligocene AFT and ZHe ages in the center of the profiles allows us to frame the period of Alpine exhumation from 39 to 29 Ma, at a rate of 0.24-0.3 km Myr-1. Moreover, the reset ZHe ages imply significant burial of the samples, by up to 8-10 km in the center of the range. Therefore, the Alpine exhumation phase was significant, and synchronous to the main phase of exhumation in the central Pyrenees, although exhumation rates were an order of magnitude lower. Three-dimensional thermokinematic modeling of the data confirms the timing of uplift of this area, but its resolution is limited by the relatively small number of reset ages over a large area.

  7. Identifying key conservation threats to Alpine birds through expert knowledge.

    PubMed

    Chamberlain, Dan E; Pedrini, Paolo; Brambilla, Mattia; Rolando, Antonio; Girardello, Marco

    2016-01-01

    Alpine biodiversity is subject to a range of increasing threats, but the scarcity of data for many taxa means that it is difficult to assess the level and likely future impact of a given threat. Expert opinion can be a useful tool to address knowledge gaps in the absence of adequate data. Experts with experience in Alpine ecology were approached to rank threat levels for 69 Alpine bird species over the next 50 years for the whole European Alps in relation to ten categories: land abandonment, climate change, renewable energy, fire, forestry practices, grazing practices, hunting, leisure, mining and urbanization. There was a high degree of concordance in ranking of perceived threats among experts for most threat categories. The major overall perceived threats to Alpine birds identified through expert knowledge were land abandonment, urbanization, leisure and forestry, although other perceived threats were ranked highly for particular species groups (renewable energy and hunting for raptors, hunting for gamebirds). For groups of species defined according to their breeding habitat, open habitat species and treeline species were perceived as the most threatened. A spatial risk assessment tool based on summed scores for the whole community showed threat levels were highest for bird communities of the northern and western Alps. Development of the approaches given in this paper, including addressing biases in the selection of experts and adopting a more detailed ranking procedure, could prove useful in the future in identifying future threats, and in carrying out risk assessments based on levels of threat to the whole bird community. PMID:26966659

  8. Scenario Calculations for Alpine Snow Cover and Runoff

    NASA Astrophysics Data System (ADS)

    Bavay, M.; Lehning, M.; Jonas, T.; Loewe, H.

    2009-04-01

    The snow cover in the Alps is heavily affected by climate change. Recent data show that at altitudes below 1200 m a.s.l. a time-continuous winter snow cover is becoming an exception rather than the rule. This will also change the timing and characteristics of river runoff in Alpine catchments. A numerical study of the impact of climate change on snow cover and runoff has been conducted using ALPINE3D, a model for the high resolution simulation of alpine surface processes, in particular snow, soil and vegetation processes. We present here an assessment of future snow and runoff in two Alpine catchments, the larger Inn catchment (1945 km2) and the smaller Dischma catchment (43 km2), based on two common climate change scenarios (IPCC A2 and B2). The predicted changes in snow and runoff are drastic. While the current climate still supports permanent snow and ice at the altitudes of the highest peaks above 3000 m a.s.l., this zone will disappear under the future climate. The changes in snow cover can be summarized by approximately shifting the elevation zones down by 900 m. The corresponding changes in runoff are also severe: While the current climate shows a significant contribution from snow melt until mid to late summer, future climate will feature a much narrower snow melt runoff peak in spring. A further observation is that heavy precipitation events in the fall will change from mainly snow to mainly rain and will have a higher probability to produce flooding.

  9. Identifying key conservation threats to Alpine birds through expert knowledge

    PubMed Central

    Pedrini, Paolo; Brambilla, Mattia; Rolando, Antonio; Girardello, Marco

    2016-01-01

    Alpine biodiversity is subject to a range of increasing threats, but the scarcity of data for many taxa means that it is difficult to assess the level and likely future impact of a given threat. Expert opinion can be a useful tool to address knowledge gaps in the absence of adequate data. Experts with experience in Alpine ecology were approached to rank threat levels for 69 Alpine bird species over the next 50 years for the whole European Alps in relation to ten categories: land abandonment, climate change, renewable energy, fire, forestry practices, grazing practices, hunting, leisure, mining and urbanization. There was a high degree of concordance in ranking of perceived threats among experts for most threat categories. The major overall perceived threats to Alpine birds identified through expert knowledge were land abandonment, urbanization, leisure and forestry, although other perceived threats were ranked highly for particular species groups (renewable energy and hunting for raptors, hunting for gamebirds). For groups of species defined according to their breeding habitat, open habitat species and treeline species were perceived as the most threatened. A spatial risk assessment tool based on summed scores for the whole community showed threat levels were highest for bird communities of the northern and western Alps. Development of the approaches given in this paper, including addressing biases in the selection of experts and adopting a more detailed ranking procedure, could prove useful in the future in identifying future threats, and in carrying out risk assessments based on levels of threat to the whole bird community. PMID:26966659

  10. spatial and temporal distribution of nutrients in a linked stream-lake ecosystem

    NASA Astrophysics Data System (ADS)

    Kalinin, A. V.; Covino, T. P.; McGlynn, B. L.

    2011-12-01

    The movement of nutrients between streams and lakes can impact nutrient export and aquatic ecology in linked stream-lake ecosystems. Specifically, lakes can alter water chemistry and buffer downstream export of nutrients through physical, chemical, and biological processes. This study characterizes nitrogen storage and transport dynamics in a connected stream-lake ecosystem over the summer of 2008 in the Bull Trout Lake Watershed in the Sawtooth Mountains of central Idaho, USA. Water samples were collected for chemical analyses at the lake inflow, outflow, and at six sites across the lake, on hourly to bi-weekly intervals. Lake sampling sites were each sampled at six depths in order to capture all strata of the lake. Additionally, a dye-tracer (Rhodamine-WT) was co-injected with LiCl into the lake to determine water flow-paths and residence time distributions. Inflow and outflow fluxes, spatial and temporal distributions of dissolved organic nitrogen(DON) and dissolved inorganic nitrogen (DIN), as well as water residence times at different lake depths were evaluated. Over the summer of 2008, net influx of NO3 to the lake and net export of DON and NH4 from the lake was observed. While NO3 dominated the DIN fraction at the inflow, NH4 was dominant both at the lake outflow and within the lake, suggesting potential contributions of NH4 to the lake from adjacent wetland and groundwater sources. Differences in transport dynamics between NO3 and NH4, and temporal concentration dynamics both in the stream and lake support this hypothesis. NO3 concentrations were driven by snowmelt flushing and peaked with the hydrograph, subsequently declining for the rest of the summer. NH4 concentrations however remained stable and peaked three weeks after NO3 at the lake outflow, at a time when the contribution of snow melt water had declined and groundwater contribution increased proportionally. In the lake, NH4 and DON concentrations declined during peak runoff in May and June, and

  11. Responses Of Alpine Vegetation To Global Warming: Insights From Comparing Alpine-Restricted And Broad-Ranging Herbs Along Snowmelt Gradients

    NASA Astrophysics Data System (ADS)

    Butz, R. J.; Reinhardt, K. S.; Germino, M. J.; Kueppers, L. M.

    2009-12-01

    Many alpine plant species face habitat fragmentation and loss, and even extinction because their narrow elevation, precipitation, and temperature tolerances limit their geographic distribution. In order to assess the impacts of climate change on sensitive native alpine communities we used a variety of methods to look at the seasonal timing of life stages (phenology) and the stress responses (physiology) of alpine species along a natural environmental gradient at Niwot Ridge in the Colorado Rocky Mountains to address the following question: Will alpine plants be impaired in their existing range as a result of climate change? We collected data on date of snowmelt and vegetative and flowering phenology of all alpine species present from snowmelt to senescence in 80 1m2 plots above treeline. In addition, we measured soil temperature and moisture, plant water potential and leaf-level gas exchange early, mid, and late-season on three alpine-restricted and three broader-ranging alpine species: Geum rossii, Artemisia scopulorum, Carex rupestris, Lewisia pygmaea, Tetraneuris grandiflora, and Sibbaldia procumbens. In 2009, the natural variation in snowmelt timing was 40 days (approximately 5.5 weeks) over the 80 plots. Our results suggest that with earlier snowmelt, the number of vascular species per plot increases. However, this increase is almost exclusively attributable to wider ranging species not restricted to the alpine. Plots with intermediate natural snowmelt dates had a higher diversity of alpine-restricted species, photosynthesis, and water-use efficiency, thereby potentially increasing long-term survival rates amongst alpine species. Water stress increased in all species as the season progressed, especially in plots where snow melted earliest. Photosynthetic productivity and diversity of alpine-restricted species was greatest in plots having intermediate melt dates. These findings suggest that shifts in snowmelt date under a warming climate will likely impact the

  12. Neighborhood functions alter unbalanced facilitation on a stress gradient in an alpine treeline simulation

    NASA Astrophysics Data System (ADS)

    Malanson, G. P.; Resler, L. M.

    2014-12-01

    The stress-gradient hypothesis states that individual and species competitive and facilitative effects change in relative importance or intensity along environmental gradients of stress. The importance of the number of facilitators in the neighborhood of a potential beneficiary has not been explored. Evenly distributed and stress-correlated facilitation and the increase in the intensity of facilitation with neighbors as linear, logarithmic, and unimodal functions is simulated for two species such as Pinus albicaulis and Abies lasiocarpa. The mutualism is unbalanced in that the establishment of one species is enhanced by neighbors more than the other. Compared to no facilitation or evenly distributed facilitation, the stress gradient produces more edges in the spatially advancing population, more overall intensity of facilitation, and more individuals further advanced into the area of higher stress; the more enhanced species has increased population relative to the other - to the point where they are equal. Among three neighborhood functions, little difference exists in outcomes between the linear and logarithmic functions, but the unimodal function, which shifts peak facilitation intensity to fewer neighbors, increases the above state variables more than the differences between the even and stress gradient facilitation scenarios. The unbalanced mutualism may be important at treeline ecotones where the spatial pattern becomes central to facilitation.

  13. Lake Nasser and Toshka Lakes, Egypt

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Lake Nasser (center) and the Toshka Lakes (center left) glow emerald green and black in this MODIS true-color image acquired March 8, 2002. Located on and near the border of Egypt and Norther Sudan, these lakes are an oasis of water in between the Nubian (lower right) and Libyan Deserts (upper left). Also visible are the Red Sea (in the upper right) and the Nile River (running north from Lake Nasser). Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

  14. Aspects on muscle properties and use in competitive Alpine skiing.

    PubMed

    Tesch, P A

    1995-03-01

    This brief report describes the physiological demands in competitive Alpine skiing as well as the physiological profile of elite skiers. Maximal heart rate is typically attained by the end of either of the four Alpine ski disciplines. The giant slalom probably calls for the largest reliance upon aerobic energy metabolism and oxygen uptake may increase to 75%-100% of maximal aerobic power. Although high caliber skiers typically show increased maximal aerobic power, it is unlikely that this is an important factor determining success in skiing. Also, anaerobic energy provision accounts for more than half of the total energy yield. Accordingly, plasma and muscle lactate accumulation is substantial after a single race. Similarly, during skiing there is a high rate of glycogen utilization that eventually may result in depletion of muscle glycogen stores by the end of a day of intense skiing. Muscles of Alpine skiers do not possess a distinct fiber type composition and, if anything, skiers tend to show a preponderance of slow twitch fibers. This concords with the recruitment of both muscle fiber types during slalom or giant slalom. Elite skiers show increased knee extensor strength. This seems warranted because there is great reliance upon slow and forceful eccentric muscle actions when performing turns in the giant slalom or slalom. PMID:7752855

  15. Slip localization on the southern Alpine Fault, New Zealand

    NASA Astrophysics Data System (ADS)

    Barth, N. C.; Boulton, C.; Carpenter, B. M.; Batt, G. E.; Toy, V. G.

    2013-06-01

    of a detailed field study of the southern onshore portion of New Zealand's Alpine Fault reveal that for 75 km along-strike, dextral-normal slip on this long-lived structure is highly localized in phyllosilicate-rich fault core gouges and along their contact with more competent rocks. At three localities (Martyr River, McKenzie Creek, and Hokuri Creek), we document complete cross sections through the fault. New 40Ar/39Ar dates on mylonites, combined with microstructural and mechanical data on phyllosilicate-rich fault core gouges show that modern slip is localized onto a single, steeply dipping 1 to 12 m-thick fault core composed of impermeable (k = 10-20 to 10-22 m2), frictionally weak (μs = 0.12-0.37), velocity-strengthening, illite-chlorite, and saponite-chlorite-lizardite fault gouges. Fault core materials are (1) comparable to those of other major weak-cored faults (e.g., San Andreas Fault) and (2) most compatible with fault creep, despite paleoseismic evidence of quasiperiodic large magnitude earthquakes (Mw > 7) on this portion of the Alpine Fault. We conclude that frictional properties of gouges at the surface do not characterize the overall seismogenic behavior of the southern Alpine Fault.

  16. Numerical simulation of a turning alpine ski during recreational skiing.

    PubMed

    Hirano, Y; Tada, N

    1996-09-01

    While downhill snow skiing, recreational alpine skiers enjoy making turning motions with their skis. These motions are mainly induced by skidding, while turning by alpine ski racers is made by carving a trace in the snow. In the present study we treat the turning motions by recreational alpine skiers. This "skidding" turning motion is made possible by centripetal forces acting on the ski and skier dynamic motion systems, with these forces arising due to the skier placing the ski's longitudinal axis at an angle that is inclined away from the velocity vector and edging the ski into the snow. When snow is soft, the edged ski creates a snow impacting force, whereas a snow cutting force occurs when it is hard. Here, we calculate the former force using a three-dimensional water jet analogy, while the latter one using conventional metal cutting theory, after which the corresponding equations of motion for each system are derived and numerically solved. This methodology enables simulating the curvilinear and rotational motion of the ski and skier systems. Resultant simulations quantitatively show for the first time that the resultant radius of curvature of a ski track while downhill skiing is strongly dependent on the location of the ski boot on the ski's longitudinal axis and also on its side-cut (midlength taper). PMID:8883012

  17. Changes in alpine plant growth under future climate conditions

    NASA Astrophysics Data System (ADS)

    Rammig, A.; Jonas, T.; Zimmermann, N. E.; Rixen, C.

    2010-06-01

    Alpine shrub- and grasslands are shaped by extreme climatic conditions such as a long-lasting snow cover and a short vegetation period. Such ecosystems are expected to be highly sensitive to global environmental change. Prolonged growing seasons and shifts in temperature and precipitation are likely to affect plant phenology and growth. In a unique experiment, climatology and plant growth was monitored for almost a decade at 17 snow meteorological stations in different alpine regions along the Swiss Alps. Regression analyses revealed highly significant correlations between mean air temperature in May/June and snow melt out, onset of plant growth, and plant height. These correlations were used to project plant growth phenology for future climate conditions based on the gridded output of a set of regional climate models runs. Melt out and onset of growth were projected to occur on average 17 days earlier by the end of the century than in the control period from 1971-2000 under the future climate conditions of the low resolution climate model ensemble. Plant height and biomass production were expected to increase by 77% and 45%, respectively. The earlier melt out and onset of growth will probably cause a considerable shift towards higher growing plants and thus increased biomass. Our results represent the first quantitative and spatially explicit estimates of climate change impacts on future growing season length and the respective productivity of alpine plant communities in the Swiss Alps.

  18. Changes in alpine plant growth under future climate conditions

    NASA Astrophysics Data System (ADS)

    Rammig, A.; Jonas, T.; Zimmermann, N. E.; Rixen, C.

    2009-11-01

    Alpine shrub- and grasslands are shaped by extreme climatic conditions such as a long-lasting snow cover and a short vegetation period. Such ecosystems are expected to be highly sensitive to global environmental change. Prolonged growing seasons and shifts in temperature and precipitation are likely to affect plant phenology and growth. In a unique experiment, climatology and plant growth was monitored for almost a decade at 17 snow meteorological stations in different alpine regions along the Swiss Alps. Regression analyses revealed highly significant correlations between mean air temperature in May/June and snow melt-out, onset of plant growth, and plant height. These correlations were used to project plant growth phenology for future climate conditions based on the gridded output of a set of regional climate models runs. Melt-out and onset of growth were projected to occur on average 17 days earlier by the end of the century than in the control period from 1971-2000 under the future climate conditions of the low resolution climate model ensemble. Plant height and biomass production were expected to increase by 77% and 45%, respectively. The earlier melt-out and onset of growth will probably cause a considerable shift towards higher growing plants and thus increased biomass. Our results represent the first quantitative and spatially explicit estimates of climate change impacts on future growing season length and the respective productivity of alpine plant communities in the Swiss Alps.

  19. Comparison modeling for alpine vegetation distribution in an arid area.

    PubMed

    Zhou, Jihua; Lai, Liming; Guan, Tianyu; Cai, Wetao; Gao, Nannan; Zhang, Xiaolong; Yang, Dawen; Cong, Zhentao; Zheng, Yuanrun

    2016-07-01

    Mapping and modeling vegetation distribution are fundamental topics in vegetation ecology. With the rise of powerful new statistical techniques and GIS tools, the development of predictive vegetation distribution models has increased rapidly. However, modeling alpine vegetation with high accuracy in arid areas is still a challenge because of the complexity and heterogeneity of the environment. Here, we used a set of 70 variables from ASTER GDEM, WorldClim, and Landsat-8 OLI (land surface albedo and spectral vegetation indices) data with decision tree (DT), maximum likelihood classification (MLC), and random forest (RF) models to discriminate the eight vegetation groups and 19 vegetation formations in the upper reaches of the Heihe River Basin in the Qilian Mountains, northwest China. The combination of variables clearly discriminated vegetation groups but failed to discriminate vegetation formations. Different variable combinations performed differently in each type of model, but the most consistently important parameter in alpine vegetation modeling was elevation. The best RF model was more accurate for vegetation modeling compared with the DT and MLC models for this alpine region, with an overall accuracy of 75 % and a kappa coefficient of 0.64 verified against field point data and an overall accuracy of 65 % and a kappa of 0.52 verified against vegetation map data. The accuracy of regional vegetation modeling differed depending on the variable combinations and models, resulting in different classifications for specific vegetation groups. PMID:27307276

  20. Alpine Lakes Wilderness Additions and Pratt and Middle Fork Snoqualmie Rivers Protection Act

    THOMAS, 113th Congress

    Sen. Murray, Patty [D-WA

    2013-01-23

    06/21/2013 Referred to the Subcommittee on Public Lands and Environmental Regulation. (All Actions) Notes: For further action, see H.R.3979, which became Public Law 113-291 on 12/19/2014. Tracker: This bill has the status Passed SenateHere are the steps for Status of Legislation:

  1. Alpine Lakes Wilderness Additions and Pratt and Middle Fork Snoqualmie Rivers Protection Act

    THOMAS, 113th Congress

    Rep. Reichert, David G. [R-WA-8

    2013-01-23

    12/22/2014 Placed on the Union Calendar, Calendar No. 517. (All Actions) Notes: For further action, see H.R.3979, which became Public Law 113-291 on 12/19/2014. Tracker: This bill has the status IntroducedHere are the steps for Status of Legislation:

  2. Temporal Patterns of Airborne Pesticides in Alpine Lakes of the Sierra Nevada, California

    EPA Science Inventory

    Airborne agricultural pesticides are being transported many tens of kilometers to remote mountain areas, and have been implicated as a causal agent for recent, dramatic population declines of several amphibian species in such locations. Largely unmeasured, however, are the magnit...

  3. Historical decline and altered congener patterns of polychlorinated dibenzo-p-dioxins and dibenzofurans in fish and sediment in response to process changes at a pulp mill discharging into Jackfish Bay, Lake Superior.

    PubMed

    Dahmer, Shari C; Tetreault, Gerald R; Hall, Roland I; Munkittrick, Kelly R; McMaster, Mark E; Servos, Mark R

    2015-11-01

    Improved regulations for pulp and paper mill effluents and an industry shift away from elemental chlorine bleaching in the 1990s greatly reduced the release of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) into the environment. However, the high potential of these contaminants to persist in sediment and bioaccumulate in biota means that they have remained a concern. To document current contamination from bleached kraft pulp mill effluent, PCDD/Fs were measured in white sucker (Catostomus commersoni) collected from Jackfish Bay, Lake Superior. These values were contrasted to historically reported fish data as well as PCDD/F patterns from dated sediment cores. Patterns of PCDD/Fs in sediment cores from Jackfish Bay and reference sites demonstrated a relationship between contamination and mill process changes. During the peak PCDD/F contamination period (1991), when the mill was still using elemental chlorine, the contamination patterns in fish and sediment were distinct and dominated by 2,3,7,8-tetrachlorodibenzo-p-dioxin and 2,3,7,8-tetrachlorodibenzofuran. Following the reduction in the use of elemental chlorine during the early 1990s, a rapid decline was observed in PCDD/F contamination of fish tissue, and levels are now approaching background conditions with congener patterns more reflective of atmospheric sources. Although surface sediments from Jackfish Bay continue to have elevated PCDD/Fs, with some locations exceeding sediment quality guidelines, they do not appear to be highly bioavailable to benthic fish. PMID:26468966

  4. Alpine biodiversity and assisted migration: The case of the American pika (Ochotona princeps)

    USGS Publications Warehouse

    Wilkening, Jennifer L.; Ray, Chris; Ramsay, Nathan G.; Klingler, Kelly

    2015-01-01

    Alpine mammals are predicted to be among the species most threatened by climate change, due to the projected loss and further fragmentation of alpine habitats. As temperature or precipitation regimes change, alpine mammals may also be faced with insurmountable barriers to dispersal. The slow rate or inability to adjust to rapidly shifting environmental conditions may cause isolated alpine species to become locally extirpated, resulting in reduced biodiversity. One proposed method for mitigating the impacts of alpine species loss is assisted migration. This method, which involves translocating a species to an area with more favourable climate and habitat characteristics, has become the subject of debate and controversy in the conservation community. The uncertainty associated with climate change projections, coupled with the thermal sensitivity of many alpine mammals, makes it difficult to a priori assess the efficacy of this technique as a conservation management tool. Here we present the American pika (Ochotona princeps) as a case study. American pikas inhabit rocky areas throughout the western US, and populations in some mountainous areas have become locally extirpated in recent years. We review known climatic and habitat requirements for this species, and also propose protocols designed to reliably identify favourable relocation areas. We present data related to the physiological constraints of this species and outline specific requirements which must be addressed for translocation of viable populations, including wildlife disease and genetic considerations. Finally, we discuss potential impacts on other alpine species and alpine communities, and overall implications for conserving alpine biodiversity in a changing climate.

  5. In-Lake Processes Offset Increased Terrestrial Inputs of Dissolved Organic Carbon and Color to Lakes

    PubMed Central

    Köhler, Stephan J.; Kothawala, Dolly; Futter, Martyn N.; Liungman, Olof; Tranvik, Lars

    2013-01-01

    Increased color in surface waters, or browning, can alter lake ecological function, lake thermal stratification and pose difficulties for drinking water treatment. Mechanisms suggested to cause browning include increased dissolved organic carbon (DOC) and iron concentrations, as well as a shift to more colored DOC. While browning of surface waters is widespread and well documented, little is known about why some lakes resist it. Here, we present a comprehensive study of Mälaren, the third largest lake in Sweden. In Mälaren, the vast majority of water and DOC enters a western lake basin, and after approximately 2.8 years, drains from an eastern basin. Despite 40 years of increased terrestrial inputs of colored substances to western lake basins, the eastern basin has resisted browning over this time period. Here we find the half-life of iron was far shorter (0.6 years) than colored organic matter (A420 ; 1.7 years) and DOC as a whole (6.1 years). We found changes in filtered iron concentrations relate strongly to the observed loss of color in the western basins. In addition, we observed a substantial shift from colored DOC of terrestrial origin, to less colored autochthonous sources, with a substantial decrease in aromaticity (-17%) across the lake. We suggest that rapid losses of iron and colored DOC caused the limited browning observed in eastern lake basins. Across a wider dataset of 69 Swedish lakes, we observed greatest browning in acidic lakes with shorter retention times (< 1.5 years). These findings suggest that water residence time, along with iron, pH and colored DOC may be of central importance when modeling and projecting changes in brownification on broader spatial scales. PMID:23976946

  6. Lake salinity variations resulting from wind direction, Gobi Desert, China

    NASA Astrophysics Data System (ADS)

    Bradley, D. C.; Cartwright, I.; Currell, M.

    2010-12-01

    s increased density causes it to sink back into the groundwater. In this way, the prevailing wind effectively keeps the fresh and saline waters separate, even though they are part of the same water body. This process is susceptible to even small disturbances. In the developed lakes, this trend is no longer observed, as the system has been interrupted by buildings causing changes to the wind flow, or alternatively, animals and/or human population have altered the water flow, simply through the act of entering the lakes and mixing the lake waters.

  7. 3D mapping and simulation of Geneva Lake environmental data

    NASA Astrophysics Data System (ADS)

    Villard, Roch; Maignan, Michel; Kanevski, Mikhail; Rapin, Francois; Klein, Audrey

    2010-05-01

    The Geneva Lake is the biggest alpine and subalpine lake in central Europe. The depth of this lake is 309 meters and its total volume of water is 89 billions m3. It takes, on average, around twelve years so that waters of the lake are completely brewed. Furthermore the Geneva lake waters are rich in dissolved substances as carbonate, sulfate. The quantity of particles in suspension in the lake, which mainly arrived from the Rhône, is nowadays around height million of tones. The International Commission for the Leman Lake (CIPEL) works about the improvement of the quality of this lake since 1962. In the present study three dimensional environmental data (temperature, oxygen and nitrate) which cover the period from 1954 to 2008, for a total of 27'500 cases are investigated. We are interested to study the evolution of the temperature of the lake because there is an impact on the reproduction of fishes and also because the winter brewing of the water makes the re-oxygenation of deep-water. In order that biological balance is maintained in a lake, there must be enough oxygen in the water. Moreover, we work on nitrate distribution and evolution because contributions in fertilizers cause eutrophication of lake. The data are very numerous when we consider the time series, some of them with more than 300 occurrences, but there are between 2 and 15 data available for spatial cartography. The basic methodology used for the analysis, mapping and simulations of 3D patterns of environmental data is based on geostatistical predictions (family of kriging models) and conditional stochastic simulations. Spatial and temporal variability, 3D monitoring networks changing over time, make this study challenging. An important problem is also to make interpolation/simulations over a long period of time, like ten years. One way used to overcome this problem, consists in using a weighted average of ten variograms during this period. 3D mapping was carried out using environment data for

  8. Estimated flood flows in the Lake Tahoe basin, California and Nevada

    USGS Publications Warehouse

    Crompton, E. James; Hess, Glen W.; Williams, Rhea P.

    2002-01-01

    Lake Tahoe, the largest alpine lake in North America, covers about 192 square miles (mi2) of the 506-mi2 Lake Tahoe Basin, which straddles the border between California and Nevada (Fig. 1). In cooperation with the Nevada Department of Transportation (NDOT), the U.S. Geological Survey (USGS) estimates the flood frequencies of the streams that enter the lake. Information about potential flooding of these streams is used by NDOT in the design and construction of roads and highways in the Nevada portion of the basin. The stream-monitoring network in the Lake Tahoe Basin is part of the Lake Tahoe Interagency Monitoring Program (LTIMP), which combines the monitoring and research efforts of various Federal, State, and regional agencies, including both USGS and NDOT. The altitude in the basin varies from 6,223 feet (ft) at the lake's natural rim to over 10,000 ft along the basin's crest. Precipitation ranges from 40 inches per year (in/yr) on the eastern side to 90 in/yr on the western side (Crippen and Pavelka, 1970). Most of the precipitation comes during the winter months as snow. Precipitation that falls from June through September accounts for less than 20 percent of the annual total.

  9. Contrasting diversity of phycodnavirus signature genes in two large and deep western European lakes.

    PubMed

    Zhong, Xu; Jacquet, Stéphan

    2014-03-01

    Little is known about Phycodnavirus (or double-stranded DNA algal virus) diversity in aquatic ecosystems, and virtually, no information has been provided for European lakes. We therefore conducted a 1-year survey of the surface waters of France's two largest lakes, Annecy and Bourget, which are characterized by different trophic states and phytoplanktonic communities. We found complementary and contrasting diversity of phycodnavirus in the lakes based on two genetic markers, the B family DNA polymerase-encoding gene (polB) and the major capsid protein-encoding gene (mcp). These two core genes have already been used, albeit separately, to infer phylogenetic relationships and genetic diversity among members of the phycodnavirus family and to determine the occurrence and diversity of these genes in natural viral communities. While polB yielded prasinovirus-like sequences, the mcp primers yielded sequences for prasinoviruses, chloroviruses, prymnesioviruses and other groups not known from available databases. There was no significant difference in phycodnavirus populations between the two lakes when the sequences were pooled over the full year of investigation. By comparing Lakes Annecy and Bourget with data for other aquatic environments around the world, we show that these alpine lakes are clearly distinct from both other freshwater ecosystems (lakes and rivers) and marine environments, suggesting the influence of unique biogeographic factors. PMID:23889778

  10. Great Lakes rivermouths: a primer for managers

    USGS Publications Warehouse

    Pebbles, Victoria; Larson, James; Seelbach, Paul

    2013-01-01

    Between the North American Great Lakes and their tributaries are the places where the confluence of river and lake waters creates a distinct ecosystem: the rivermouth ecosystem. Human development has often centered around these rivermouths, in part, because they provide a rich array of ecosystem services. Not surprisingly, centuries of intense human activity have led to substantial pressures on, and alterations to, these ecosystems, often diminishing or degrading their ecological functions and associated ecological services. Many Great Lakes rivermouths are the focus of intense restoration efforts. For example, 36 of the active Great Lakes Areas of Concern (AOCs) are rivermouths or areas that include one or more rivermouths. Historically, research of rivermouth ecosystems has been piecemeal, focused on the Great Lakes proper or on the upper reaches of tributaries, with little direct study of the rivermouth itself. Researchers have been divided among disciplines, agencies and institutions; and they often work independently and use disparate venues to communicate their work. Management has also been fragmented with a focus on smaller, localized, sub-habitat units and socio-political or economic elements, rather than system-level consideration. This Primer presents the case for a more holistic approach to rivermouth science and management that can enable restoration of ecosystem services with multiple benefits to humans and the Great Lakes ecosystem. A conceptual model is presented with supporting text that describes the structures and processes common to all rivermouths, substantiating the case for treating these ecosystems as an identifiable class.1 Ecological services provided by rivermouths and changes in how humans value those services over time are illustrated through case studies of two Great Lakes rivermouths—the St. Louis River and the Maumee River. Specific ecosystem services are identified in italics throughout this Primer and follow definitions described

  11. Speculations on the spatial setting and temporal evolution of a fjord-style lake

    NASA Astrophysics Data System (ADS)

    Sarnthein, M.; Spötl, C.

    2012-04-01

    The Inn Valley, a classical region of Quaternary research in the Alps, is bordered by terraces that extend over almost 70 km and record an ancient lake with a lake level near 750-830 m above sea level (a.s.l.), about 250-300 m above the modern valley floor. Over large distances, the terrace sediments consist mainly of laminated "Banded Clays", above ~750 m a.s.l. overlain by glaciofluvial gravel and finally, by tills that record the Upper Würmian ice advance of Marine Isotope Stage (MIS) 2. In the (former) clay pit of Baumkirchen this boundary forms the Alpine type locality for the onset of the Upper Würmian, well supported by 14C-based age control first established by Fliri (1971). On the basis of a recently cored sediment section at Baumkirchen, the >200 m thick "Banded Clays" store a continuous, largely undisturbed, highly resolved, and widely varved climatic archive of MIS 3. Major unknowns concern the location and origin of dams that may have barred the vast and deep Inn Valley lake. We discuss potential linkages to the pattern of moraines and ice advance of MIS 4 glaciers, which was less prominent than during MIS 2, thus leading to a distinct east-west segment¬ation of the run-off systems in Tyrol. East of Imst, for example, the lake was possibly barred by both a rock sill reaching up to 830 m a.s.l. and a lateral moraine deposited by an Ötz Valley glacier. 80 km further east, a lateral moraine of a glacier advancing from the Ziller Valley may have barred the ancient Inn Valley lake to the east. The final rapid coarsening of clastic lake sediments at the end of MIS 3 is widely ascribed to major climatic deter¬ioration. However, the MIS 3-2 boundary was linked to an only modest change of global climates and accordingly, different forcings may be considered. In turn, the rapid coarsening may document a date, when the Central Alpine glaciers had already filled the basin of Imst to the west of the Inn Valley lake. This ice mass may have forced the melt

  12. Ice Regime and Melt-out Timing Cause Divergent Hydrologic Responses among Arctic Lakes

    NASA Astrophysics Data System (ADS)

    Bondurant, A.; Arp, C. D.; Jones, B. M.; Liljedahl, A. K.; Hinkel, K. M.; Welker, J. M.

    2015-12-01

    Lakes are prevalent in the Arctic and thus play a key role in regional hydrology. Because many lakes are shallow and ice grows thick (historically 2-m or greater), lakes often freeze solid (bedfast ice) and this condition fundamentally alters lake energy balance and melt-out processes compared to deeper lakes with perennial liquid water below floating ice. Our analysis of lakes in northern Alaska indicated that ice-off in bedfast ice lakes occurred on average 17 days earlier (22-June) than ice-off in adjacent floating ice lakes (9-July). Earlier melt in bedfast ice lakes caused higher open-water evaporation, 28 % on average, relative to floating ice lakes and this divergence increased in lakes closer to the coast and in cooler summers. Specific conductivity and water isotopes (18O and 2H) indicated similar differences in evaporation between these lake types. Our analysis suggests that ice regimes and associated ice-out timing currently create a strong hydrologic divergence among Arctic lakes, which makes understanding the distribution and dynamics of lakes by ice regime essential for predicting regional hydrology. An observed trend towards more floating ice lakes due to thinner ice growth may initially offset lake drying because of lower evaporative loss from this lake type. This potential negative feedback caused by winter processes is in spite of an overall projected increase in evapotranspiration as the Arctic climate warms. The unusually warm spring observed in 2015 caused much earlier lake ice-out throughout Arctic Alaska, thus providing perfect conditions to test these hypotheses concerning differential lake hydrologic responses.

  13. Lake herring (Coregonus artedi) and rainbow smelt (Osmerus mordax) diets in western Lake Superior

    USGS Publications Warehouse

    Johnson, Timothy B.; Brown, William P.; Corry, Timothy D.; Hoff, Michael H.; Scharold, Jill V.; Trebitz, Anett S.

    2004-01-01

    We describe the diets of lake herring (Coregonus artedi) and rainbow smelt (Osmerus mordax) in western Lake Superior during the summers of 1996 and 1997. Both species consumed predominantly (> 71% by number) zooplankton, showing a preference for larger taxa. Diet overlap between the two species was low (Schoener's index = 0.42). Mysis was most important in rainbow smelt diets, whereas Diaptomus sicilis was most important in lake herring diets. Rainbow smelt selected larger taxa, and larger individuals within a taxon when compared to lake herring, although rainbow smelt tended to be smaller fish. Fish diets have changed relative to previous studies and may be reflecting changes in the zooplankton community. Continued changes in the fish and zooplankton community will alter predatorprey and energetic pathways, ultimately affecting growth and production of the ecosystem.

  14. Lakes Ecosystem Services Online

    EPA Science Inventory

    Northeastern lakes provide valuable ecosystem services that benefit residents and visitors and are increasingly important for provisioning of recreational opportunities and amenities. Concurrently, however, population growth threatens lakes by, for instance, increasing nutrient ...

  15. Utah: Salt Lake Region

    Atmospheric Science Data Center

    2014-05-15

    article title:  Winter and Summer Views of the Salt Lake Region     View Larger Image Magnificent views of the region surrounding Salt Lake City, Utah are captured in these winter and summer images from the ...

  16. Lake trout rehabilitation in Lake Ontario

    USGS Publications Warehouse

    Elrod, Joseph H.; O'Gorman, Robert; Schneider, Clifford P.; Eckert, Thomas H.; Schaner, Ted; Bowlby, James N.; Schleen, Larry P.

    1995-01-01

    Attempts to maintain the native lake trout (Salvelinus namaycush) population in Lake Ontario by stocking fry failed and the species was extirpated by the 1950s. Hatchery fish stocked in the 1960s did not live to maturity because of sea lamprey (Petromyzon marinus) predation and incidental commercial harvest. Suppression of sea lampreys began with larvicide treatments of Lake Ontario tributaries in 1971 and was enhanced when the tributaries of Oneida Lake and Lake Erie were treated in the 1980s. Annual stocking of hatchery fish was resumed with the 1972 year class and peaked at about 1.8 million yearlings and 0.3 million fingerlings from the 1985–1990 year classes. Survival of stocked yearlings declined over 50% in the 1980 s and was negatively correlated with the abundance of lake trout > 550 mm long (r = −0.91, P < 0.01, n = 12). A slot length limit imposed by the State of New York for the 1988 fishing season reduced angler harvest. Angler harvest in Canadian waters was 3 times higher in eastern Lake Ontario than in western Lake Ontario. For the 1977–1984 year classes, mean annual survival rate of lake trout age 6 and older was 0.45 (range: 0.35–0.56). In U.S. waters during 1985–1992, the total number of lake trout harvested by anglers was about 2.4 times greater than that killed by sea lampreys. The number of unmarked lake trout < 250 mm long in trawl catches in 1978–1992 was not different from that expected due to loss of marks and failure to apply marks at the hatchery, and suggested that recruitment of naturally-produced fish was nil. However, many of the obstacles which may have impeded lake trout rehabilitation in Lake Ontario during the 1980s are slowly being removed, and there are signs of a general ecosystem recovery. Significant recruitment of naturally produced lake trout by the year 2000, one interim objective of the rehabilitation plan for the Lake, may be achieved.

  17. Elevation, Substrate, & Climate effects on Alpine & Sub-Alpine Plant Distribution in California & Nevada's High Mountains: Preliminary Data from the California and Nevada GLORIA Project

    NASA Astrophysics Data System (ADS)

    Barber, A.; Millar, C.

    2014-12-01

    Documenting plant response to global climate change in sensitive zones, such as the alpine, is a major goal for global change biology. Basic information on alpine plant distribution by elevation and substrate provides a basis for anticipating which species may decline in a warming climate. The Global Observation Research Initiative in Alpine Environments (GLORIA) is a worldwide effort to document vegetation changes over time in alpine settings using permanent multi-summit plots. The California/Nevada group currently monitors seven permanent GLORIA target regions, composed of 29 summits in alpine and subalpine zones. Summits range in elevations from 2918m to 4325m on substrates including dolomite, granite, quartzite, and volcanics. High-resolution plant occurrence and cover data from the upper 10 meters of each summit are presented. Plants from our target regions can be divided into three groups: summit specialists found only on the highest peaks, alpine species found predominantly within the alpine zone, and broadly distributed species found in the alpine zone and below. Rock substrate and microsite soil development have a strong influence on plant communities and species richness. We present the first set of five-year resurvey and temperature data from 18 summits. We have documented some annual variation in species presence/absence at almost all sites, but no dramatic changes in total diversity. Consistent with the expectation of rising global temperatures, our soil temperature loggers have documented temperature increases at most of our sites. These data are a baseline for assessing bioclimatic shifts and future plant composition in California and Nevada's alpine zone.

  18. Changes in selenium, copper, cadmium, and zinc concentrations in mullet (Mugil cephalus) from the southern basin of Lake Macquarie, Australia, in response to alteration of coal-fired power station fly ash handling procedures.

    PubMed

    Kirby, J; Maher, W; Harasti, D

    2001-08-01

    Selenium, copper, cadmium, and zinc concentrations were measured in mullet (Mugil cephalus) from the southern basin of Lake Macquarie, Australia, in 1997 to determine if improved ash-handling practices at an adjacent coal fired power station, implemented in 1995, had significantly lowered trace metal concentrations in mullet tissues. Mean muscle tissue concentrations of selenium (5.9 +/- 0.7 microg/g dry mass), copper (3.6 +/- 0.1 microg/g dry mass), and zinc (14 +/- 1 microg/g dry mass) are lower than previously reported for mullet analyzed in 1993 (10 +/- 2, 21 +/- 3, 27 +/- 3 microg/g dry mass, respectively). Cadmium concentrations in liver tissues increased from 2.3 +/- 0.3 to 6 +/- 2 microg/g dry mass. Significant intra-tissue correlations between metal concentrations were found for all tissues except muscle. Strong correlations of selenium, copper, and zinc concentrations were found in liver tissues, indicating a common primary source may exist for these metals, such as fly ash. All trace metals were found to have significant inter-tissue correlations, with strong correlations occurring for selenium between all tissues and for cadmium between all tissues except muscle. Regulation of copper, cadmium, and zinc appears to be occurring in muscle tissue. Selenium concentrations in mullet are still above levels considered to be of concern to human consumers. Trace metal concentrations are below that known to effect the health of fish. Mullet are directly exposed to trace metal concentrations as a result of feeding and the ingestion of contaminated sediment and detritus. Lower metal concentrations found in mullet tissues are attributed to the burial of highly contaminated sediment with material containing lower trace metal concentrations. Little of the variations in trace metal concentrations between mullet was explained by mass, gender, or age. PMID:11462141

  19. Forest gaps slow the sequestration of soil organic matter: a humification experiment with six foliar litters in an alpine forest

    PubMed Central

    Ni, Xiangyin; Yang, Wanqin; Tan, Bo; Li, Han; He, Jie; Xu, Liya; Wu, Fuzhong

    2016-01-01

    Humification of plant litter containing carbon and other nutrients greatly contributes to the buildup of soil organic matter, but this process can be altered by forest gap-induced environmental variations during the winter and growing seasons. We conducted a field litterbag experiment in an alpine forest on the eastern Tibetan Plateau from November 2012 to October 2014. Six dominant types of foliar litter were placed on the forest floor in various forest gap positions, including gap centre, canopy gap, expanded gap and closed canopy. Over two years of incubation, all foliar litters were substantially humified especially during the first winter, although the newly accumulated humic substances were young and could be decomposed further. The forest gaps exhibited significant effects on early litter humification, but the effects were regulated by sampling seasons and litter types. Compared with the litter under the closed canopy, humification was suppressed in the gap centre after two years of field incubation. The results presented here suggest that gap formation delays the accumulation of soil organic matter, and reduces soil carbon sequestration in these alpine forests. PMID:26790393

  20. Alpine Skiing With total knee ArthroPlasty (ASWAP): impact on molecular and architectural features of musculo-skeletal ageing.

    PubMed

    Narici, M; Conte, M; Salvioli, S; Franceschi, C; Selby, A; Dela, F; Rieder, F; Kösters, A; Müller, E

    2015-08-01

    This study investigated features of skeletal muscle ageing in elderly individuals having previously undergone unilateral total knee arthroplasty (TKA) and whether markers of sarcopenia could be mitigated by a 12-week alpine skiing intervention. Novel biomarkers agrin, indicative of neuromuscular junction (NMJ) degeneration, tumor suppressor protein p53, associated with muscle atrophy, and a new ultrasound-based muscle architecture biomarker were used to characterize sarcopenia. Participant details and study design are presented by Kösters et al. (2015). The results of this study show that NMJ degeneration is widespread among active septuagenarians previously subjected to TKA: all participants showed elevated agrin levels upon recruitment. At least 50% of individuals were identified as sarcopenic based on their muscle architecture, supporting the hypothesis that NMJ alterations precede sarcopenia. Notably, sarcopenia was strongly associated with the expression of p53, which seems to confirm its validity as a biomarker of muscle atrophy. Training did not significantly modify any of these biomarkers. In view of the lack of accretion of muscle mass in response to the alpine skiing intervention, we hypothesize that local muscle inflammation and oxidative stress may have blunted the anabolic response to training and promoted muscle breakdown in this elderly post-TKA population. PMID:26083700

  1. Forest gaps slow the sequestration of soil organic matter: a humification experiment with six foliar litters in an alpine forest.

    PubMed

    Ni, Xiangyin; Yang, Wanqin; Tan, Bo; Li, Han; He, Jie; Xu, Liya; Wu, Fuzhong

    2016-01-01

    Humification of plant litter containing carbon and other nutrients greatly contributes to the buildup of soil organic matter, but this process can be altered by forest gap-induced environmental variations during the winter and growing seasons. We conducted a field litterbag experiment in an alpine forest on the eastern Tibetan Plateau from November 2012 to October 2014. Six dominant types of foliar litter were placed on the forest floor in various forest gap positions, including gap centre, canopy gap, expanded gap and closed canopy. Over two years of incubation, all foliar litters were substantially humified especially during the first winter, although the newly accumulated humic substances were young and could be decomposed further. The forest gaps exhibited significant effects on early litter humification, but the effects were regulated by sampling seasons and litter types. Compared with the litter under the closed canopy, humification was suppressed in the gap centre after two years of field incubation. The results presented here suggest that gap formation delays the accumulation of soil organic matter, and reduces soil carbon sequestration in these alpine forests. PMID:26790393

  2. Measurements of spectral optical properties and their relation to biogeochemical variables and processes in Crater Lake, Crater Lake National Park, OR

    USGS Publications Warehouse

    Boss, E.S.; Collier, R.; Larson, G.; Fennel, K.; Pegau, W.S.

    2007-01-01

    Spectral inherent optical properties (IOPs) have been measured at Crater Lake, OR, an extremely clear sub-alpine lake. Indeed Pure water IOPs are major contributors to the total IOPs, and thus to the color of the lake. Variations in the spatial distribution of IOPs were observed in June and September 2001, and reflect biogeochemical processes in the lake. Absorption by colored dissolved organic material increases with depth and between June and September in the upper 300 m. This pattern is consistent with a net release of dissolved organic materials from primary and secondary production through the summer and its photo-oxidation near the surface. Waters fed by a tributary near the lake's rim exhibited low levels of absorption by dissolved organic materials. Scattering is mostly dominated by organic particulate material, though inorganic material is found to enter the lake from the rim following a rain storm. Several similarities to oceanic oligotrophic regions are observed: (a) The Beam attenuation correlates well with particulate organic material (POM) and the relationship is similar to that observed in the open ocean. (b) The specific absorption of colored dissolved organic material has a value similar to that of open ocean humic material. (c) The distribution of chlorophyll with depth does not follow the distribution of particulate organic material due to photo-acclimation resulting in a subsurface pigment maximum located about 50 m below the POM maximum. ?? 2007 Springer Science+Business Media B.V.

  3. Effects of waterlogging on carbon assimilate partitioning in the Zoigê alpine wetlands revealed by 13CO2 pulse labeling

    PubMed Central

    Gao, Jun-Qin; Gao, Ju-Juan; Zhang, Xue-Wen; Xu, Xing-Liang; Deng, Zhao-Heng; Yu, Fei-Hai

    2015-01-01

    Waterlogging has been suggested to affect carbon (C) turnover in wetlands, but how it affects C allocation and stocks remains unclear in alpine wetlands. Using in situ 13CO2 pulse labelling, we investigated C allocation in both waterlogged and non-waterlogged sites in the Zoigê wetlands on the Tibetan Plateau in August 2011. More than 50% of total 13C fixed by photosynthesis was lost via shoot respiration. Shoots recovered about 19% of total 13C fixed by photosynthesis at both sites. Only about 26% of total fixed 13C was translocated into the belowground pools. Soil organic C pool accounted for 19% and roots recovered about 5–7% of total fixed 13C at both sites. Waterlogging significantly reduced soil respiration and very little 13C was lost via soil respiration in the alpine wetlands compared to that in grasslands. We conclude that waterlogging did not significantly alter C allocations among the C pools except the 13CO2 efflux derived from soil respiration and that shoots made similar contributions to C sequestration as the belowground parts in the Zoigê alpine wetlands. Therefore, changes in waterlogging due to climate change will not affect C assimilate partitioning but soil C efflux. PMID:25797457

  4. Lake Layers: Stratification.

    ERIC Educational Resources Information Center

    Brothers, Chris; And Others

    This teacher guide and student workbook set contains two learning activities, designed for fifth through ninth grade students, that concentrate on lake stratification and water quality. In the activities students model the seasonal temperature changes that occur in temperate lakes and observe the resulting stratification of lake waters. Students…

  5. Great Lakes: Chemical Monitoring

    ERIC Educational Resources Information Center

    Delfino, Joseph J.

    1976-01-01

    The Tenth Great Lakes Regional Meeting of the American Chemical Society met to assess current Chemical Research activity in the Great Lakes Basin, and addressed to the various aspects of the theme, Chemistry of the Great Lakes. Research areas reviewed included watershed studies, atmospheric and aquatic studies, and sediment studies. (BT)

  6. Great Minds? Great Lakes!

    ERIC Educational Resources Information Center

    Environmental Protection Agency, Chicago, IL. Great Lakes National Program Office.

    This book contains lesson plans that provide an integrated approach to incorporating Great Lakes environmental issues into elementary subjects. The book is divided into three subject areas: (1) History, which includes the origins of the Great Lakes, Great Lakes people, and shipwrecks; (2) Social Studies, which covers government, acid rain as a…

  7. A Killer Lake

    ERIC Educational Resources Information Center

    Horvath, Thomas

    2005-01-01

    In 1986, Lake Nyos, a volcanic lake in Cameroon, released a huge amount of carbon dioxide gas, killing over 1,700 people in the surrounding area. This case study, developed for use in a limnology or aquatic biology course, explores that event, introducing students to concepts relating to lake formation, thermal stratification, and dissolved gases.…

  8. Lakes in Valles Marineris

    NASA Astrophysics Data System (ADS)

    Lucchitta, Baerbel K.

    2010-10-01

    The paper reviews the evolution of hypotheses of lakes in Valles Marineris through observations made from the time of Mariner and continuing through the Viking, MGS, MO, MEx, and MRO missions. Several pertinent findings from these missions are addressed, including: The morphology and composition of the interior layered deposits (ILD); the question whether ILD are deposited inside the troughs or exhumed from the walls; the possible existence of ancestral basins; the derivation of water; arguments for an origin as aqueous, eolian, or pyroclastic sediments, or sub/ice volcanoes; origin of inclined layers, mounds and moats; and age relations of features within and peripheral to the troughs. A possible scenario begins with the collapse of ice-charged ground into ancestral basins along structural planes of weakness due to Tharsis stresses, about 3.5 Ga ago. The basins rapidly filled with water from ground ice, subterranean aquifers, or nearby valley networks. The water spilled out of the peripheral troughs and flowed across high plateaus into early outflow channels. The ancestral basins then filled with sediments derived from valley networks or from trapped eolian or pyroclastic deposits. Alternatively, volcanoes rose under the water or ice to form tuyas. The water was highly acidic, and sediments may have been deposited directly as evaporites or were later altered to evaporites by the brines or by hydrothermal activity. Percolating fluids produced iron oxide concretions. Similar alteration would have affected the putative volcanoes. Most of the ILD were emplaced early in the troughs' history. Shortly thereafter, more water erupted from the peripheral troughs and formed additional chaos and outflow channels. The ancestral basins were breached by erosion and tectonism, and the through-going Coprates/Ius graben system developed. Major lakes within the Valles Marineris dried up and vigorous wind erosion reduced the friable, evaporite-rich sediments to isolated mounds

  9. Lake Effects: The Lake Superior Curriculum Guide.

    ERIC Educational Resources Information Center

    Beery, Tom; And Others

    This curriculum guide was launched in response to a need for Lake Superior-specific educational materials and contains lessons and activities that can be used to teach about Lake Superior. The lessons in this book are divided into four sections. Each of the first three sections has a background section that provides basic information about Lake…

  10. Permian magmatism, Permian detachment faulting, and Alpine thrusting in the Orobic Anticline, southern Alps, Italy

    NASA Astrophysics Data System (ADS)

    Pohl, Florian; Froitzheim, Niko; Geisler-Wierwille, Thorsten; Schlöder, Oliver

    2014-05-01

    The Grassi Detachment Fault is located in the Orobic Alps east of Lake Como and was described by Froitzheim et al. (2008) as an Early Permian extensional structure. Many issues still remained unclear, like the exact timing of faulting and the extension from the well-exposed part of the detachment towards west. The Grassi Detachment Fault separates the Variscan Basement in its footwall from the volcanic and sedimentary rocks of the Early Permian Collio Formation within its hanging wall, marked by a mylonitic and cataclastic layer whose textures indicate top-to-the-southeast displacement. The footwall basement is formed by the Variscan Morbegno Gneiss and two granitic intrusions, the Val Biandino Quarz Diorite (VBQD) and the Valle Biagio Granite (VBG). The former is syntectonic with respect to the detachment, whereas for the latter, the relation to the detachment is unknown. The age of the VBQD is poorly defined as 312 Ma ± 48 Ma (Thöni et al. 1992); the VBG has not been dated. Volcanic rocks of the Collio Formation in the hanging wall may represent the extrusive part of the magmatic system. In our study area west of Val Biandino, several faults and shear zones are exposed: (1) The Grassi Detachment Fault is represented by mylonites and cataclasites with top-SE shear sense, between basement rocks and the Collio Volcanics. Towards NW, it is truncated by the unconformably overlying Late Permian Verrucano Lombardo. This may reflect the eroded culmination of a Permian metamorphic core complex. (2) A steeply NW-dipping, brittle normal fault is found further west in the footwall between VBQD and VBG. It is sealed by the basal unconformity of the Verrucano Lombardo and therefore should also be of Early Permian age (Sciunnach, 2001). It may represent an antithetic fault with respect to the detachment, accommodating the uplift of the magmatically inflated core complex. (3) The Biandino Fault is a steeply SE-dipping reverse fault, affecting also the Late Permian Verrucano

  11. Features of the Caucasian segment of the Alpine-Himalayan-Indonesian Convergence Zone

    NASA Astrophysics Data System (ADS)

    Sharkov, E.

    2012-04-01

    The Caucasus Mountain System is a part of the Cenozoic Alpine-Himalayan-Indonesian Convergence Zone (AHICZ) which lasted throughout Eurasia from Western Mediterranean to Western Pacific. This belt has been formed after closure of the Mesozoic Tethys and is marked by mountains building processes, appearance of riftogenic structures, numerous late Cenozoic basaltic plateaus, and chain of often within-continental andesite-latite volcanic arcs, which trace suture zones of the continental plates collision. Caucasus Mountains are located in eastern part of the proper Alpine Zone in zone of Arabian-Eurasian syntaxis and appeared as a result of submeridional pressure which generated by oncoming moving of these plates. The Great Caucasus is represent the south border of the Eurasian plate, uplifted along the Main Caucasian Fault (Thrust). The latter is a part of super-regional deep-seated fault ranged from the Kopetdag through Caspian Sea, Caucasus and Crimea; very likely, that its further continuation is Tornquist-Teisseyre Zone. This superfault separates areas of Alpine convergence from Eurasian plate sensu stricto. The Caucasus occurred between Black and Caspian seas with passive margins and oceanic crust, covered by sediments of 10-15 km thick. Depressions of the seas form large "downfall", or caldrons which cut off pre-Pliocene structures of Caucasus and Kopetdag. These seas are, probably, small remnants of the Tethys which gradually shallowing in the Miocene (Zonenshain, Le Pichon, 1986). New essential deepening of the Black Sea and South-Caspian deep began in the Pliocene- Quaternary; it occurred simultaneously with uprising of Crimea and Caucasus, which were not marked in relief before (Grachev, 2000). Large positive isostatic anomaly beneath the Trans-Caucasian Transverse Uplift (TCTU) of the Great Caucasus and Lesser Caucasus, which stretch out to Arabian plate, occurred between "subsides" Black and especially Caspian seas with neutral to negative isostatic

  12. Influence of glacial meltwater and humidity on evaporation of two Tibetan lakes indicated by delta 18O

    NASA Astrophysics Data System (ADS)

    Gao, J.

    2009-04-01

    delta 18O and model results are adopted to study the affects of glacial meltwater and relative humidity in two lake basins (Lakes Yamdrok-tso and Puma Yum-tso) at two different elevations on the southern Tibetan Plateau. Temporally, the lake water delta 18O of Yamdrok-tso Lake displays a seasonal fluctuation, whereas the lake water delta 18O is stable in Puma Yum-tso Lake in whole year. Spatially, the delta 18O value in Yamdrok-tso Lake is 2‰ higher than that in Puma Yum-tso Lake. delta 18O values in the two lake basins increase by 10‰ from the termini of glaciers to the lake shores, by about 1‰ from the lakeshores to the lake center, by 0.4‰ from the water surface to depth in these lakes. The largest difference, from the terminus of the Qiangyong Glacier to the depth of 35 m, is 14.1‰ and demonstrates the importance of glacial meltwater. Evaporation alters the changes of delta 18O in the two lake basins. Model results show that relative humidity is a major controlling factor of evaporation. delta 18O values of both Yamdrok-tso and Puma Yum-tso Lakes are at their steady condition, but Puma Yum-tso Lake has taken a longer time to approach the current condition, which might be attributed to higher humidity and more glacial meltwater at the lake.

  13. Factors affecting the evolution of coastal wetlands of the Laurential Great Lakes: an overview

    USGS Publications Warehouse

    Mayer, T.; Edsall, T.; Munawar, M.

    2004-01-01

    Coastal wetlands play a pivotal role in the Great Lakes ecosystem. As buffer zones between the land and open waters of the Great Lakes, they perform a variety of essential functions providing both direct and indirect anthropogenic benefits. Geology, morphology and climate are the dominant variables that influence Laurentian Great Lakes wetland development. However, anthropogenic factors are the major contributors to alteration of natural wetland processes. This paper provides an overview of natural and anthropogenic factors important in Great Lakes coastal wetland development and provides statistical information describing the Great Lakes Basin. A brief description of wetlands classification and research issues is also presented.

  14. Pb isotopes in sediments of Lake Constance, Central Europe constrain the heavy metal pathways and the pollution history of the catchment, the lake and the regional atmosphere

    SciTech Connect

    Kober, B.; Wessels, M.; Bollhoefer, A.; Mangini

    1999-05-01

    Pb isotope ratios and Pb concentrations of well-dated sediments of Lake Constance, Central Europe have been analyzed using thermal ion mass spectrometry. Sequential extraction studies indicated isotope homogeneity of the leachable Pb components within the investigated layers. Since the middle of the 19th century a significant anthropogenic Pb component appeared in the lake sediments, and rapidly approaches concentration levels similar to that of the geogenic Pb background (20 ppm) at the beginning of the 20th century. Anthropogenic Pb was predominantly transferred to the lake sediments via the atmosphere. Pb sources were coal combustion, industrial ore processing and leaded gasoline. The flux of a fluvial Pb component to the lake sediments, additive to atmospheric Pb deposition, peaked in about 1960. This flux is attributed to (re)mobilization of Pb from polluted parts of the lake catchment, and indicates the change of catchment soils from a pollution sink to a heavy metal source. The strong reduction of anthropogenic Pb in the uppermost lake sediments since the 1960s has been caused by advances of environmental protection. The lake sediments record the changing fluxes and the isotope composition of the deposited aeolian Pb pollution. During the 20th century aeolian Pb fluxes to the lake sediments were in the range of 1--4 {micro}g/cm{sup 2}/a. During peak emission periods of gasoline Pb to the atmosphere (1960--1990) the aerosol Pb isotope composition was rather constant ({sup 206}Pb/{sup 207}Pb: 1.12--1.13) and probably a mixture of Canadian and Australian with Russian and Central European Pb types. Aeolian Pb isotope and Pb flux trends in the lake sediments as a whole agree well with the trends found in Alpine glaciers (Doering et al., 1997a,b) and in ombrotrophic peat bogs of Switzerland (Shotyk et al., 1996). However, different industrial Pb components were deposited in the archives of aeolian pollution during the early 20th century.

  15. Interannual variability of snowmelt in the Sierra Nevada and Rocky Mountains, United States: examples from two alpine watersheds

    USGS Publications Warehouse

    Jepsen, Steven M.; Molotch, Noah P.; Williams, Mark W.; Rittger, Karl E.; Sickman, James O.

    2012-01-01

    The distribution of snow and the energy flux components of snowmelt are intrinsic characteristics of the alpine water cycle controlling the location of source waters and the effect of climate on streamflow. Interannual variability of these characteristics is relevant to the effect of climate change on alpine hydrology. Our objective is to characterize the interannual variability in the spatial distribution of snow and energy fluxes of snowmelt in watersheds of a maritime setting, Tokopah Basin (TOK) in California's southern Sierra Nevada, and a continental setting, Green Lake 4 Valley (GLV4) in Colorado's Front Range, using a 12 year database (1996–2007) of hydrometeorological observations and satellite-derived snow cover. Snowpacks observed in GLV4 exhibit substantially greater spatial variability than in TOK (0.75 versus 0.28 spatial coefficient of variation). In addition, modeling results indicate that the net turbulent energy flux contribution to snowmelt in GLV4 is, on average, 3 times greater in magnitude (mean 29% versus 10%) and interannual variability (standard deviation 17% versus 6%) than in TOK. These energy flux values exhibit strong seasonality, increasing as the melt season progresses to times later in the year (R2 = 0.54–0.77). This seasonality of energy flux appears to be associated with snowmelt rates that generally increase with onset date of melt (0.02 cm d-2). This seasonality in snowmelt rate, coupled to differences in hydrogeology, may account for the observed differences in correspondence between the timing of snowmelt and timing of streamflow in these watersheds.

  16. Depth, ice thickness, and ice-out timing cause divergent hydrologic responses among Arctic lakes

    NASA Astrophysics Data System (ADS)

    Arp, Christopher D.; Jones, Benjamin M.; Liljedahl, Anna K.; Hinkel, Kenneth M.; Welker, Jeffery A.

    2015-12-01

    Lakes are prevalent in the Arctic and thus play a key role in regional hydrology. Since many Arctic lakes are shallow and ice grows thick (historically 2 m or greater), seasonal ice commonly freezes to the lake bed (bedfast ice) by winter's end. Bedfast ice fundamentally alters lake energy balance and melt-out processes compared to deeper lakes that exceed the maximum ice thickness (floating ice) and maintain perennial liquid water below floating ice. Our analysis of lakes in northern Alaska indicated that ice-out of bedfast ice lakes occurred on average 17 days earlier (22 June) than ice-out on adjacent floating ice lakes (9 July). Earlier ice-free conditions in bedfast ice lakes caused higher open-water evaporation, 28% on average, relative to floating ice lakes and this divergence increased in lakes closer to the coast and in cooler summers. Water isotopes (18O and 2H) indicated similar differences in evaporation between these lake types. Our analysis suggests that ice regimes created by the combination of lake depth relative to ice thickness and associated ice-out timing currently cause a strong hydrologic divergence among Arctic lakes. Thus, understanding the distribution and dynamics of lakes by ice regime is essential for predicting regional hydrology. An observed regime shift in lakes to floating ice conditions due to thinner ice growth may initially offset lake drying because of lower evaporative loss from this lake type. This potential negative feedback caused by winter processes occurs in spite of an overall projected increase in evapotranspiration as the Arctic climate warms.

  17. Depth, ice thickness, and ice-out timing cause divergent hydrologic responses among Arctic lakes

    USGS Publications Warehouse

    Arp, Christopher D.; Jones, Benjamin M.; Liljedahl, Anna K.; Hinkel, Kenneth M.; Welker, Jeffery A.

    2015-01-01

    Lakes are prevalent in the Arctic and thus play a key role in regional hydrology. Since many Arctic lakes are shallow and ice grows thick (historically 2-m or greater), seasonal ice commonly freezes to the lake bed (bedfast ice) by winter's end. Bedfast ice fundamentally alters lake energy balance and melt-out processes compared to deeper lakes that exceed the maximum ice thickness (floating ice) and maintain perennial liquid water below floating ice. Our analysis of lakes in northern Alaska indicated that ice-out of bedfast ice lakes occurred on average 17 days earlier (22-June) than ice-out on adjacent floating ice lakes (9-July). Earlier ice-free conditions in bedfast ice lakes caused higher open-water evaporation, 28% on average, relative to floating ice lakes and this divergence increased in lakes closer to the coast and in cooler summers. Water isotopes (18O and 2H) indicated similar differences in evaporation between these lake types. Our analysis suggests that ice regimes created by the combination of lake depth relative to ice thickness and associated ice-out timing currently cause a strong hydrologic divergence among Arctic lakes. Thus understanding the distribution and dynamics of lakes by ice regime is essential for predicting regional hydrology. An observed regime shift in lakes to floating ice conditions due to thinner ice growth may initially offset lake drying because of lower evaporative loss from this lake type. This potential negative feedback caused by winter processes occurs in spite of an overall projected increase in evapotranspiration as the Arctic climate warms.

  18. Food of lake trout in Lake Superior

    USGS Publications Warehouse

    Dryer, William R.; Erkkila, Leo F.; Tetzloff, Clifford L.

    1965-01-01

    Stomachs were examined from 1,492 lake trout and 83 siscowets collected from Lake Superior. Data are given on the food of lake trout of legal size (17 inches or longer) by year, season, and depth of water, and on the relation between food and size among smaller lake trout. Fish contributed 96.7 to 99.9 per cent of the total volume of food in the annual samples. Ciscoes (Coregonus spp.) were most common (52.2 to 87.5 per cent of the volume) in 1950 to 1953 and American smelt ranked first (65.6 per cent of the volume) in 1963. Cottids were in 8.9 to 12.3 per cent of the stomachs in 1950 to 1953 but in only 4.3 per cent in 1963. Insects ranked second to fish in occurrence (9.6 per cent for the combined samples) and crustaceans followed at 3.9 per cent. The greatest seasonal changes in the food of lake trout were among fish caught at 35 fathoms and shallower. The occurrence of Coregonus increased from 34.6 per cent in February-March to 71.1 per cent in October-December. Smelt were in 76.9 per cent of the stomachs in February-March but in only 2.2 per cent in October-December. Cottids, Mysis relicta, and insects were most common in the July-September collections. Lake trout taken at depths greater than 35 fathoms had eaten a higher percentage of Cottidae and Coregonus than had those captured in shallower water. Smelt, ninespine sticklebacks, Mysis, and insects were more frequent in stomachs of lake trout from less than 35 fathoms. Crustaceans comprised more than 70 per cent of the total volume of food for 4.0- to 7.9-inch lake trout but their importance decreased as the lake trout grew larger. Pontoporeia affinis was the most common in the stomachs of 4.0- to 6.9-inch lake trout and Mysis held first rank at 7.0 to 12.9 inches. Ostracods were important only to 4.0- to 4.9-inch lake trout. As the lake trout became larger, the importance of fish grew from 4.4-per cent occurrence at 5.0 to 5.9 inches to 93.9 per cent at 16.0 to 16.9 inches. Smelt were most commonly eaten by

  19. Carbon cycling in Lake Superior

    NASA Astrophysics Data System (ADS)

    Urban, N. R.; Auer, M. T.; Green, S. A.; Lu, X.; Apul, D. S.; Powell, K. D.; Bub, L.

    2005-06-01

    Carbon (C) cycling in Lake Superior was studied within the Keweenaw Interdisciplinary Transport Experiment in Superior (KITES) project to assess (1) whether the lake is net heterotrophic, (2) sources, sinks and residence time for dissolved organic carbon (DOC), (3) importance of terrigenous organic C subsidies, and (4) factors limiting C flow through bacteria. During 3 years of fieldwork, measurements were made of spatial and temporal distributions of C pools and rates of photosynthesis, community respiration, and bacterial production. Measurements were made of the composition of dissolved organic matter (DOM), rates of DOM photolysis, lability of DOM toward microbial consumption, and river inputs of DOM. All measurements suggest the lake is net heterotrophic. The C:N ratios of DOM suggest that it is primarily of terrigenous origin, but other characteristics (size distribution, UV absorption) point to the presence of autochthonous DOM and to alteration of terrigenous material. The lake mass balance indicates that the residence time (˜8 years) of the DOC pool (17 Tg) is short relative to the hydrologic residence time (170 years). The known flux of terrigenous DOC (˜1 Tg/yr) is too low to support annual bacterial carbon demand (6-38 Tg/yr), but microbial respiration is the major sink for terrigenous DOC. A rapidly cycling, autochthonous DOC pool must exist. Microbial activity was correlated with temperature, phosphorus availability, and DOC concentration but not with photosynthesis rates. Measurements of respiration (˜40 Tg/yr), photosynthesis (2-7 Tg/yr), and bacterial production (0.5-2 Tg/yr) are not all mutually compatible and result in a discrepancy in the organic carbon budget.

  20. Limnology of the Green Lakes Valley: phytoplankton ecology and dissolved organic matter biogeochemistry at a long-term ecological research site

    USGS Publications Warehouse

    Miller, Matthew P.; McKnight, Diane M.

    2015-01-01

    Background: Surface waters are the lowest points in the landscape, and therefore serve as excellent integrators and indicators of changes taking place in the surrounding terrestrial and atmospheric environment. Aims: Here we synthesise the findings of limnological studies conducted during the past 15 years in streams and lakes in the Green Lakes Valley, which is part of the Niwot Ridge Long-term Ecological Research (LTER) Site. Methods: The importance of these studies is discussed in the context of aquatic ecosystems as indicators, integrators, and regulators of environmental change. Specifically, investigations into climatic, hydrologic, and nutrient controls on present-day phytoplankton, and historical diatom, community composition in the alpine lake, Green Lake 4, are reviewed. In addition, studies of spatial and temporal patterns in dissolved organic matter (DOM) biogeochemistry and reactive transport modelling that have taken place in the Green Lakes Valley are highlighted. Results and conclusions: The findings of these studies identify specific shifts in algal community composition and DOM biogeochemistry that are indicative of changing environmental conditions and provide a framework for detecting future environmental change in the Green Lakes Valley and in other alpine watersheds. Moreover, the studies summarised here demonstrate the importance of long-term monitoring programmes such as the LTER programme.

  1. High-resolution regional paleoclimate simulations of Lake Bonneville and its influence on geomorphic processes in the Uinta Mountains during the Last Glacial Maximum (Invited)

    NASA Astrophysics Data System (ADS)

    Galewsky, J.

    2013-12-01

    Reconstructed equilibrium line altitudes (ELAs) for alpine glaciers in the Uinta Mountains at the Last Glacial Maximum (LGM) increase with distance from the shoreline of pluvial Lake Bonneville, an effect that has been linked at least in part to enhanced precipitation derived from Lake Bonneville. While this result is broadly consistent with relatively large-scale climate modeling studies, the precise meteorological mechanisms by which Lake Bonneville may have influenced the glacial geomorphology of the Uinta Mountains remain poorly understood. New, high resolution (4km grid spacing) quasi-idealized regional paeoclimate simulations of the LGM computed with the Weather Research and Forecast (WRF) model provide new insights into these processes. Preliminary results indicate that moisture derived from Lake Bonneville likely would not have exerted a significant impact on regional precipitation unless the lake temperature exceeded about 4 degrees C. However, an ice-free Lake Bonneville would have likely exerted a modest (at least 1-2C) local warming, with associated impacts on precipitation and snowpack development. While the overall snowfall amounts do not appear to be greatly affected by the presence of a cold, ice-free lake, the presence of such a lake does appear to influence precipitation extremes throughout the region. These results suggest that the local temperature influence of pluvial lakes on regional glaciation may be of similar magnitude to the effects of enhanced evaporation from those lakes.

  2. Seepage measurements from Long Lake, Indiana Dunes National Lakeshore

    USGS Publications Warehouse

    Isiorho, S.A.; Beeching, F.M.; Stewart, P.M.; Whitman, R.L.

    1996-01-01

    Long Lake, located near Lake Michigan within the dune-complexes of Indiana Dunes National Lakeshore, USA, was formed some time during the Pleistocene and Holocene epochs. A surficial aquifer underlies Long Lake, which is either a source or sink for the later. The hydrologic processes in the lakeshore and surrounding environs have been significantly altered during the agricultural, municipal, and industrial development of the region. Limited data suggest that the organisms of Long Lake have elevated levels of several contaminants. This study attempts to quantify seepage within the lake to assess the potential threat to groundwater quality. Seepage measurements and minipiezometric tests were used to determine seepage within the lake. Seepage measurements and minipiezometric tests suggest that water seeps out of Long Lake, thus recharging the groundwater that flows southwest away from the lake. There is a great deal of variability in the seepage rate, with a mean of 11.5×10-4±11.2×10-4 m d-1. The mean seepage rate of 0.3 m yr-1 for Long Lake is greater than the 0.2 m yr-1 recharge rate estimated for the drainage basin area. The Long Lake recharge volume of 2.5 × 105 m3 yr-1 is approximately 22% of the volume of the lake and is significant when compared to the total surface recharge volume of 4.8 × 105 m3 yr-1 to the upper aquifer of the drainage area. There is a potential for contamination of the groundwater system through seepage from the lake from contaminants derived from aerial depositions.

  3. Water quality of Lake Austin and Town Lake, Austin, Texas

    SciTech Connect

    Andrews, F.L.; Wells, F.C.; Shelby, W.J.; McPherson, E.M.

    1988-01-01

    Lake Austin and Town Lake are impoundments on the Colorado River in Travis County, central Texas, and are a source of water for municipal industrial water supplies, electrical-power generation, and recreation for more than 500,000 people in the Austin metropolitan area. Small vertical temperature variations in both lakes were attributed to shallow depths in the lakes and short retention times of water in the lakes during the summer months. The largest areal variations in dissolved oxygen generally occur in Lake Austin during the summer as a result of releases of water from below the thermocline in Lake Travis. Except for iron, manganese, and mercury, dissolved concentrations of trace elements in water collected from Lake Austin and Town Lake did not exceed the primary or secondary drinking water standards set by the US Environmental Protection Agency. Little or no effect of stormwater runoff on temperature, dissolved oxygen, or minor elements could be detected in either Lake Austin or Town Lake. Little seasonal or areal variation was noted in nitrogen concentrations in Lake Austin or Town lake. Total phosphorus concentrations generally were small in both lakes. Increased concentrations of nitrogen and phosphorus were detected after storm runoff inflow in Town Lake, but not in Lake Austin; densities of fecal-coliform bacteria increased in Lake Austin and Town Lake, but were substantially greater in Town Lake than in Lake Austin. 18 refs., 38 figs., 59 tabs.

  4. [Recreational and competitive alpine skiing. Typical injury patterns and possibilities for prevention].

    PubMed

    Brucker, P U; Katzmaier, P; Olvermann, M; Huber, A; Waibel, K; Imhoff, A B; Spitzenpfeil, P

    2014-01-01

    Alpine skiing is the most popular winter sport discipline in Germany and is performed by more than 4 million recreational sportsmen and ski racing athletes. Compared to other sports, however, the injury rate in alpine skiing is quite high. Especially the knee joint is the most commonly injured area of the musculoskeletal system. Knee injuries are classified as severe in a high percentage of cases. In this review article, epidemiologic data and typical injury patterns in recreational alpine skiing and in competitive alpine ski racing are compared. In addition, the potentials of preventive methods in alpine skiing are presented and evaluated with a special focus on orthotic devices and protection wear as injury prevention equipment. PMID:24445993

  5. Lake trout rehabilitation in Lake Huron

    USGS Publications Warehouse

    Eshenroder, Randy L.; Payne, N. Robert; Johnson, James E.; Bowen, Charles, II; Ebener, Mark P.

    1995-01-01

    Efforts to restore lake trout (Salvelinus namaycush) in Lake Huron after their collapse in the 1940s were underway in the early 1970s with completion of the first round of lampricide applications in tributary streams and the stocking of several genotypes. We assess results of rehabilitation and establish a historical basis for comparison by quantifying the catch of spawning lake trout from Michigan waters in 1929-1932. Sixty-eight percent of this catch occurred in northern waters (MH-1) and most of the rest (15%) was from remote reefs in the middle of the main basin. Sea lampreys (Petromyzon marinus) increased in the early 1980s in the main basin and depressed spawning populations of lake trout. This increase was especially severe in northern waters and appeared to be associated with untreated populations in the St. Marys River. Excessive commercial fishing stemming from unresolved treaty rights also contributed to loss of spawning fish in northern Michigan waters. Seneca-strain lake trout did not appear to be attacked by sea lampreys until they reached a size > 532 mm. At sizes > 632 mm, Seneca trout were 40-fold more abundant than the Marquette strain in matched-planting experiments. Natural reproduction past the fry stage has occurred in Thunder Bay and South Bay, but prospects for self-sustaining populations of lake trout in the main basin are poor because sea lampreys are too abundant, only one side of the basin is stocked, and stocking is deferred to allow commercial gillnetting in areas where most of the spawning occurred historically. Backcross lake trout, a lake trout x splake (s. Fontinalis x s. Namaycush) hybrid, did not reproduce in Georgian Bay, but this genotype is being replaced with pure-strain lake trout, whose early performance appears promising.

  6. Warming Contracts Flowering Phenology in an Alpine Ecosystem

    NASA Astrophysics Data System (ADS)

    Jabis, M. D.; Winkler, D. E.; Kueppers, L. M.

    2015-12-01

    In alpine ecosystems where temperature increases associated with anthropogenic climate change are likely to be amplified, the flowering phenology of plants may be particularly sensitive to changes in environmental signals. For example, earlier snowmelt and higher temperature have been found to be important factors driving plant emergence and onset of flowering. However, few studies have examined the interactive role of soil moisture in response to warming. Using infrared heating to actively warm plots crossed with manual watering over the growing season in a moist alpine meadow at Niwot Ridge, Colorado, our preliminary results indicate that community-level phenology (length of flowering time across all species) was contracted with heating but was unaffected by watering. At the species level, additional water extended the length of the flowering season by one week for almost half (43%) of species. Heating, which raised plant and surface soil temperatures (+1.5 C) advanced snowmelt by ~7.6 days days and reduced soil moisture by ~2%, advanced flowering phenology for 86% of species. The response of flowering phenology to combined heating and watering was predominantly a heating effect. However, watering did appear to mitigate advances in end of flowering for 22% of species. The length of flowering season, for some species, appears to be tied, in part, to moisture availability as alleviating ambient soil moisture stress delayed phenology in unheated plots. Therefore, we conclude that both temperature and moisture appear to be important factors driving flowering phenology in this alpine ecosystem. The relationship between flowering phenology and species- or community-level productivity is not well established, but heating advanced community peak productivity by 5.4 days, and also reduced peak productivity unless additional water was provided, indicating some consistency between drivers of productivity and drivers of flowering phenology.

  7. Alpine Snow Cover - Water Resources in Arid Regions

    NASA Astrophysics Data System (ADS)

    Czyzowska, E. H.; Van Leeuwen, W. J.; Hirschboeck, K. K.; Wisniewski, W. T.; Marsh, S. E.

    2013-12-01

    There is an undisputed need to increase accuracy of snow cover estimation in regions of complex terrain, especially in areas dependent on winter snow accumulation for a substantial portion of their water supply, such as the Western United States, Central Asia, and the Andes. Presently, the most pertinent monitoring and research needs related to alpine snow cover extent (SCE) are: (1) to improve SCE monitoring by providing detailed fractional snow cover (FSC) products which perform well in temporal/spatial heterogeneous forested and/or alpine terrains; (2) to provide accurate measurements of FSC at the watershed scale for use in snow water equivalent (SWE) estimation for regional water management; (3) to provide detailed distributions of FSC in mountainous regions to investigate the temporal/spatial distribution of SCE/SWE in relation to recent climate changes; (4) to use FSC products as input for climate models at multiple scales; and (5) to estimate SCE and SWE for use in ecological studies (e.g., vegetation cover, water stress, primary production, fire, insect outbreaks, and pulses in tree demography). To address the above our approach is based on Landsat/MODIS Fractional Snow Cover (LandsatFSC, ModisFSC), as a measure of the temporal/spatial distribution of alpine SCE. We used a fusion methodology between remotely sensed multispectral data from Landsat TM/ETM+/MODIS and Ikonos utilized at their highest respective spatial resolutions. Artificial Neural Networks (ANNs) are used to capture the multi-scale information structure of the data by means of the ANN training process, followed by the ANN extracting FSC from all available information in the Landsat images. The LandsatFSC/ModisFSC algorithms were validated (RMSE ~ 0.09; mean error ~ 0.001-0.01 FSC) in watersheds characterized by diverse environmental factors such as: terrain, slope, exposition, vegetation cover, and wide-ranging snow cover conditions.

  8. Microbial biodiversity in Alpine Permo-Triassic rock salt

    NASA Astrophysics Data System (ADS)

    Radax, C.; Wieland, H.; Pfaffenhuemer, M.; Leuko, S.; Rittmann, S.; Weidler, G.; Gruber, C.; Stan-Lotter, H.

    2003-04-01

    Alpine Permo-Triassic rock salt (age 200-250 million years) was shown several times to contain living extremely halophilic Archaea. These organisms might stem from ancient populations that became entrapped and persisted in the rock salt since then. For this reason, rock salt is considered a promising model system for the search for bacterial extraterrestrial life. In our studies on biodiversity in Alpine rock salt, we employed both culture-dependent and culture-independent, PCR-based methods. The latter approach indicated the presence of at least 12 distinct sequence types (phylotypes) in our samples, all of which belonged to the extremely halophilic Archaea. None of the recovered sequences was identical to sequences from databases, suggesting the avoidance of contaminants during experimental procedures. Two phylotypes could be assigned to taxonomically described members of this family; the remaining ten phylotypes appeared only remotely related to known genera of the extremely halophilic Archaea. In contrast, attempts to isolate organisms from the same sample on 15 different growth media so far yielded only two groups of isolates that could be differentiated based on their 16S rRNA genes. One group was very similar to Halococcus strains that we frequently isolated from Alpine rock salt; the other group was closely correlated to one of our novel phylotypes. Analyses of whole cell protein patterns allowed to further differentiate the latter group into two different subgroups that could not be distinguished at the molecular level. These results show that both culture-dependent and culture-independent strategies have to be applied in order to obtain a more complete view of microbial biodiversity in Permo-Triassic rock salt: culture-independent methods yield information on the gross microbial diversity in rock salt, whereas subtle differences can currently only be registered between cultivated strains.

  9. A molecular phylogeny of Alpine subterranean Trechini (Coleoptera: Carabidae)

    PubMed Central

    2013-01-01

    Background The Alpine region harbours one of the most diverse subterranean faunas in the world, with many species showing extreme morphological modifications. The ground beetles of tribe Trechini (Coleoptera, Carabidae) are among the best studied and widespread groups with abundance of troglobionts, but their origin and evolution is largely unknown. Results We sequenced 3.4 Kb of mitochondrial (cox1, rrnL, trnL, nad1) and nuclear (SSU, LSU) genes of 207 specimens of 173 mostly Alpine species, including examples of all subterranean genera but two plus a representation of epigean taxa. We applied Bayesian methods and maximum likelihood to reconstruct the topology and to estimate divergence times using a priori rates obtained for a related ground beetle genus. We found three main clades of late Eocene-early Oligocene origin: (1) the genus Doderotrechus and relatives; (2) the genus Trechus sensu lato, with most anisotopic subterranean genera, including the Pyrenean lineage and taxa from the Dinaric Alps; and (3) the genus Duvalius sensu lato, diversifying during the late Miocene and including all subterranean isotopic taxa. Most of the subterranean genera had an independent origin and were related to epigean taxa of the same geographical area, but there were three large monophyletic clades of exclusively subterranean species: the Pyrenean lineage, a lineage including subterranean taxa from the eastern Alps and the Dinarides, and the genus Anophthalmus from the northeastern Alps. Many lineages have developed similar phenotypes independently, showing extensive morphological convergence or parallelism. Conclusions The Alpine Trechini do not form a homogeneous fauna, in contrast with the Pyrenees, and show a complex scenario of multiple colonisations of the subterranean environment at different geological periods and through different processes. Examples go from populations of an epigean widespread species going underground with little morphological modifications to

  10. 3D cartographic modeling of the Alpine arc

    NASA Astrophysics Data System (ADS)

    Vouillamoz, Naomi; Sue, Christian; Champagnac, Jean-Daniel; Calcagno, Philippe

    2012-12-01

    We built a 3D cartography of the Alpine arc, a highly non-cylindrical mountain belt, using the 3D GeoModeller of the BRGM (French geological survey). The model allows to handle the large-scale 3D structure of seventeen major crustal units of the belt (from the lower crust to the sedimentary cover nappes), and two main discontinuities (the Insubric Line and the Crustal Penninic Front). It provides a unique document to better understand their structural relationships and to produce new sections. The study area comprises the western Alpine arc, from the Jura to the Northwest, up to the Bergell granite intrusion and the Lepontine Dome to the East, and is limited to the South by the Ligurian basin. The model is limited vertically 10 km above sea level at the top, and the moho interface at the bottom. We discarded the structural relationships between the Alps sensus stricto and the surrounding geodynamic systems such as the Rhine graben or the connection with the Apennines. The 3D-model is based on the global integration of various data such as the DEM of the Alps, the moho isobaths, the simplified geological and tectonic maps of the belt, the crustal cross-sections ECORS-CROP and NFP-20, and complementary cross-sections specifically built to precise local complexities. The database has first been integrated in a GIS-project to prepare their implementation in the GeoModeller, by homogenizing the different spatial referencing systems. The global model is finally interpolated from all these data, using the potential field method. The final document is a new tri-dimensional cartography that would be used as input for further alpine studies.

  11. Protection of large alpine infrastructures against natural hazards

    NASA Astrophysics Data System (ADS)

    Robl, Jörg; Scheikl, Manfred; Hergarten, Stefan

    2013-04-01

    Large infrastructures in alpine domains are threatened by a variety of natural hazards like debris flows, rock falls and snow avalanches. Especially linear infrastructure including roads, railway lines, pipe lines and power lines passes through the entire mountain range and the impact of natural hazards can be expected along a distance over hundreds of kilometers. New infrastructure projects like storage power plants or ski resorts including access roads are often located in remote alpine domains without any historical record of hazardous events. Mitigation strategies against natural hazards require a detailed analysis on the exposure of the infrastructure to natural hazards. Following conventional concepts extensive mapping and documentation of surface processes over hundreds to several thousand km² of steep alpine domain is essential but can be hardly performed. We present a case study from the Austrian Alps to demonstrate the ability of a multi-level concept to describe the impact of natural hazards on infrastructure by an iterative process. This includes new state of the art numerical models, modern field work and GIS-analysis with an increasing level of refinement at each stage. A set of new numerical models for rock falls, debris flows and snow avalanches was designed to operate with information from field in different qualities and spatial resolutions. Our analysis starts with simple and fast cellular automata for rockfalls and debrisflows to show the exposure of the infrastructure to natural hazards in huge domains and detects "high risk areas" that are investigated in more detail in field in the next refinement level. Finally, sophisticated 2D- depth averaged fluid dynamic models for all kinds of rapid mass movements are applied to support the development of protection structures.

  12. Models for the Filling of Crater Lake, Oregon

    NASA Astrophysics Data System (ADS)

    Nathenson, M.; Bacon, C. R.; Gardner, J. V.

    2001-12-01

    Crater Lake partially fills, to a depth of 593 m, the 10-km-diameter, 1200-m-deep caldera formed by collapse of Mount Mazama volcano. The lake receives water from direct precipitation and inflow from the caldera walls and loses water by surface evaporation and leakage. No streams flow from Crater Lake. A high-resolution multibeam echo sounding survey of the lake floor conducted in 2000 (Gardner et al., 2001) revealed seven drowned beaches between 1849 and 1878 m elevation (reference lake elevation is 1883 m). The beaches are thought to reflect drier periods in the lake's history since the climactic, caldera-forming eruption of Mount Mazama, approximately 7,700 years ago. The shallowest drowned beach at 1878 m represents the deepest part of a wave-cut platform up to 100 m wide, substantially wider than any of the beaches, where erodible talus or intensely altered rocks are present. The great width of the platform compared to the width of the drowned beaches indicates that the lake has mostly been near its current level during the lake's history. Unambiguous evidence of former highstands above 1883 m has not been reported. In order to explain the occurrence of the drowned beaches and their relatively narrow depth range, leakage through the caldera walls must vary with depth and cannot occur just at the lake bottom or at the modern lake level. A reasonable model is that leakage is proportional to elevation above the bottom of the lake. Recognition that there is a thick layer of relatively permeable debris resting on glaciated lava in the northeast caldera wall above an elevation of 1845 m suggests a variant of this model where leakage is proportional to elevation above 1845 m. Climate studies indicate that Crater Lake began to fill during a dry period. Assuming that precipitation at that time was 70% of modern and that the beach at 1853 m (the deeper beach is somewhat suspect) corresponds to this amount of precipitation, a combination of the above leakage models is

  13. Continuous recording of seismic signals in Alpine permafrost

    NASA Astrophysics Data System (ADS)

    Hausmann, H.; Krainer, K.; Staudinger, M.; Brückl, E.

    2009-04-01

    Over the past years various geophysical methods were applied to study the internal structure and the temporal variation of permafrost whereof seismic is of importance. For most seismic investigations in Alpine permafrost 24-channel equipment in combination with long data and trigger cables is used. Due to the harsh environment source and geophone layouts are often limited to 2D profiles. With prospect for future 3D-layouts we introduce an alternative of seismic equipment that can be used for several applications in Alpine permafrost. This study is focussed on controlled and natural source seismic experiments in Alpine permafrost using continuous data recording. With recent data from an ongoing project ("Permafrost in Austria") we will highlight the potential of the used seismic equipment for three applications: (a) seismic permafrost mapping of unconsolidated sediments, (b) seismic tomography in rock mass, and (c) passive seismic monitoring of rock falls. Single recording units (REFTEK 130, 6 channels) are used to continuously record the waveforms of both the seismic signals and a trigger signal. The combination of a small number of recording units with different types of geophones or a trigger allow numerous applications in Alpine permafrost with regard to a high efficiency and flexible seismic layouts (2D, 3D, 4D). The efficiency of the light and robust seismic equipment is achieved by the simple acquisition and the flexible and fast deployment of the (omni-directional) geophones. Further advantages are short (data and trigger) cables and the prevention of trigger errors. The processing of the data is aided by 'Seismon' which is an open source software project based on Matlab® and MySQL (see SM1.0). For active-source experiments automatic stacking of the seismic signals is implemented. For passive data a program for automatic detection of events (e.g. rock falls) is available which allows event localization. In summer 2008 the seismic equipment was used for the

  14. Geometry and kinematics of extension in Alpine Corsica

    NASA Astrophysics Data System (ADS)

    Jolivet, Laurent; Daniel, Jean-Marc; Fournier, Marc

    1991-06-01

    The geometry of the most recent deformation in Alpine Corsica is discussed in terms of reactivation of thrusts as normal faults and crustal extension, following crustal thickening in late Cretaceous and Eocene time. A cross section interpreted in terms of obduction in previous works is shown here to be a result of ductile and brittle extension in late Oligocene and Early Miocene time. This new interpretation is based on field observations of the brittle and ductile structures and their relations to the metamorphic history in the Tenda-col de Teghime and Centuri regions, as well as additional observations in other parts of Alpine Corsica. The following geological features are observed: (1) The recent deformation was partly achieved during a top-to-the-east ductile shear close to the brittle-ductile transition and was later superimposed by brittle shear indicating a transition in time from ductile to brittle regime. (2) Extensional brittle structures in the Early Miocene Saint Florent limestone and sense of tilt are compatible with the eastward sense of shear observed in the ductile rocks. (3) The movement along major "thrust" contacts is associated with retrograde metamorphism which overprinted the early high- P-low- T paragenesis at less severe P-T conditions. They also bring tectonic units with contrasted metamorphic evolutions into close contacts. (4) There is a regional correlation between retromorphosis and recent deformation since the high- P-low- T paragenesis are better preserved in southern of Alpine Corsica where the recent deformation is less pervasive. (5) Highly non-coaxial deformation is localized along east-dipping shear zones close to brittle normal faults which bounds tilted Miocene basins; in between the geometry is more symmetric and the finite strain therefore more coaxial. (6) Late extensional brittle structures are observed at many sites in the metamorphic rocks. In the present paper we discussed these first-order observations and describe the

  15. Detecting alpine permafrost using electro-magnetic methods

    NASA Astrophysics Data System (ADS)

    Hauck, Christian; Mühll, Daniel Vonder

    In the European Alps, thawing permafrost caused by warmer temperatures has been recognised as a possible danger for slope instabilities in the past few years. The permanently frozen layer (permafrost) is often only a few metres thick. Consequently it is very vulnerable to small changes in local climate. Furthermore, the detection and localisation of such shallow permafrost sites is difficult. The heterogeneity of the material and the difficult access of the steep slopes make commonly used techniques such as reflection seismics or Ground Penetrating Radar (GPR) less adequate for alpine permafrost studies.

  16. Sediment connectivity evolution on an alpine catchment undergoing glacier retreat

    NASA Astrophysics Data System (ADS)

    Goldin, Beatrice; Rudaz, Benjamin; Bardou, Eric

    2014-05-01

    Climate changes can result in a wide range of variations of natural environment including retreating glaciers. Melting from glaciers will have a significant impact on the sediment transport characteristics of glacierized alpine catchments that can affect downstream channel network. Sediment connectivity assessment, i.e. the degree of connections that controls sediment fluxes between different segments of a landscape, can be useful in order to address management activity on sediment fluxes changes of alpine streams. Through the spatial characterization of the connectivity patterns of a catchment and its potential evolution it is possible to both define sediment transport pathways and estimate different contributions of the sub-catchment as sediment sources. In this study, a topography based index (Cavalli et al., 2013) has been applied to assess spatial sediment connectivity in the Navisence catchment (35 km2), an alpine basin located in the southern Walliser Alps (Switzerland) characterized by a complex glacier system with well-developed lateral moraines on glacier margins already crossed by several lateral channels. Glacier retreat of the main glacial edifice will provide a new connectivity pattern. At present the glacier disconnects lateral slopes from the main talweg: it is expected that its retreat will experience an increased connectivity. In order to study this evolution, two high resolution (2 m) digital terrain models (DTMs) describing respectively the terrain before and after glacier retreat have been analyzed. The current DTM was obtained from high resolution photogrammetry (2 m resolution). The future DTM was derived from application of the sloping local base level (SLBL) routine (Jaboyedoff et al., 2004) on the current glacier system, allowing to remove the ice body by reconstituting a U-shaped polynomial bedrock surface. From this new surface a coherent river network was drawn and slight random noise was added. Finally the river network was burned into

  17. Dynamics and structure of the Alpine Fold Belt

    NASA Technical Reports Server (NTRS)

    Kahle, H. G.

    1985-01-01

    The structure and present-day dynamics of the Alps interms of geodesy and gravimetry are discusssed. A strong correlation of precise leveling and isostatic gravity along the central Alpine chain, especially in Canton Graubunden, East Switzerland are shown. It is assumed that the uplift is partly controlled by isostatic rebound effects. Field observations indicate that these phenomena are still active in the Alps. The study of the uplift processes by applying a number of geodetic and gravimetric measuring techniques, such as the determination of nonperiodic secular variations of gravity, of the deflections of the vertical and tilt changes monitored by hydrostatic leveling is proposed.

  18. Primary dispersal of supraglacial debris and debris cover formation on alpine glaciers

    NASA Astrophysics Data System (ADS)

    Kirkbride, M. P.; Deline, P.

    2009-04-01

    Debris-covered glaciers are receiving increased attention due to the modulation of runoff by supraglacial covers, and to the lake outburst flood hazard at many covered glacier termini. Observed increases in debris cover extents cannot presently be explained in terms of glaciological influences. The supply of englacial debris to the supraglacial zone has previously been understood only in terms of local dispersal due to differential ablation between covered and uncovered ice, for example on medial moraines. Here, we introduce the term primary dispersal to describe the process of migration of the outcrops of angled debris septa across melting, thinning ablation zones. Understanding primary debris dispersal is an essential step to understanding how supraglacial debris cover is controlled by glaciological variables, and hence is sensitive to climatically-induced fluctuation. Three measures of a glacier's ability to evacuate supraglacial debris are outlined: (1) a concentration factor describing the focussing of englacial debris into specific supraglacial mass loads; (2) the rate of migration of a septum outcrop relative to the local ice surface; and (3) a downstream velocity differential between a septum outcrop and the ice surface. (1) and (2) are inversely related, while (3) increases downglacier to explain why slow-moving, thinning ice rapidly becomes debris covered. Data from Glacier d'Estelette (Italian Alps) illustrate primary dispersal processes at a site where debris cover is increasing in common with many other shrinking alpine glaciers. We develop a model of the potential for debris cover formation and growth in different glaciological environments. This explains why glaciers whose termini are obstructed often have steep debris septa feeding debris covers which vary slowly in response to mass balance change. In contrast, at glaciers with gently-dipping debris-bearing foliation, the debris cover extent is sensitive to glaciological change. These findings

  19. Modeling rates of life form cover change in burned and unburned alpine heathland subject to experimental warming.

    PubMed

    Camac, James S; Williams, Richard J; Wahren, Carl-Henrik; Jarrad, Frith; Hoffmann, Ary A; Vesk, Peter A

    2015-06-01

    Elevated global temperatures are expected to alter vegetation dynamics by interacting with physiological processes, biotic relationships and disturbance regimes. However, few studies have explicitly modeled the effects of these interactions on rates of vegetation change, despite such information being critical to forecasting temporal patterns in vegetation dynamics. In this study, we build and parameterize rate-change models for three dominant alpine life forms using data from a 7-year warming experiment. These models allowed us to examine how the interactions between experimental warming, the abundance of bare ground (a measure of past disturbance) and neighboring life forms (a measure of life form interaction) affect rates of cover change in alpine shrubs, graminoids and forbs. We show that experimental warming altered rates of life form cover change by reducing the negative effects of neighboring life forms and positive effects of bare ground. Furthermore, we show that our models can predict the observed direction and rate of life form cover change at burned and unburned long-term monitoring sites. Model simulations revealed that warming in unburned vegetation is expected to result in increased forb and shrub cover and decreased graminoid cover. In contrast, in burned vegetation, warming is predicted to slow post-fire regeneration in both graminoids and forbs and facilitate rapid expansion in shrub cover. These findings illustrate the applicability of modeling rates of vegetation change using experimental data. Our results also highlight the need to account for both disturbance and the abundance of other life forms when examining and forecasting vegetation dynamics under climatic change. PMID:25694042

  20. Are viruses important in the plankton of highly turbid glacier-fed lakes?

    PubMed Central

    Drewes, Fabian; Peter, Hannes; Sommaruga, Ruben

    2016-01-01

    Viruses are ubiquitous in aquatic ecosystems where they significantly contribute to microbial mortality. In glacier-fed turbid lakes, however, viruses not only encounter low host abundances, but also a high number of suspended mineral particles introduced by glacier meltwaters. We hypothesized that these particles potentially lead to unspecific adsorption and removal of free virus from the plankton, and thus significantly reduce their abundance in this type of lake. We followed the distribution of free virus-like particles (VLP) during the ice-free season across a turbidity gradient in four alpine lakes including one adjacent clear system where hydrological connectivity to the receding glacier is already lost. In the glacier-fed turbid lakes, VLP abundance increased with distance to the glacier, but the highest numbers were observed in the clear lake by the end of August, coinciding with the maximum in prokaryotic abundance. Our results suggest that viral loss by attachment to particles is less important than expected. Nevertheless, the relatively lower variability in VLP abundance and the lower virus-to-prokaryote ratio found in the turbid lakes than in the clear one point to a rather low temporal turnover and thus, to a reduced impact on microbial communities. PMID:27094854

  1. Quantifying Hydraulic Conductivity and Fluid Pressures in the Alpine Fault Hanging-Wall Using DFDP-2 Data and Numerical Models

    NASA Astrophysics Data System (ADS)

    Coussens, J. P.; Woodman, N. D.; Menzies, C. D.; Teagle, D. A. H.; Sutherland, R.; Capova, L.; Cox, S.; Upton, P.; Townend, J.; Toy, V.

    2015-12-01

    Fluid flow can play an important role in fault failure, due to the influence of pore pressure on effective confining stress and through chemical and thermal alteration of the fault zone. Rocks of the Alpine Fault Zone, both exposed at the surface and recovered in cores, show evidence for significant alteration by fluids. However, the fluid flow regime in the region is poorly constrained and its relationship with the behaviour of the fault is uncertain. In 2014 the Deep Fault Drilling Project (DFDP) drilled the DFDP-2B borehole, penetrating 893 m into the hanging-wall of the Alpine Fault. Prior to drilling, a set of hydrogeological models for the Whataroa Valley region, encompassing the DFDP-2B drill site, were constructed using the modelling software FEFLOW. Models were constructed for a range of plausible hydraulic conductivity structures for the region. They predicted strongly artesian hydraulic heads of 50-150 m above surface elevation and temperatures exceeding 100 °C within 1 km depth in bedrock beneath the DFDP-2 drill site, with the exact hydraulic and thermal gradients dependent on the hydraulic conductivity structure chosen. During the drilling project hydraulic and thermal data from the borehole was collected. This included 33 slug test datasets, carried out at a range of borehole depths throughout the project. Estimates for hydraulic conductivity were obtained by analysis of slug test data. Steady state hydraulic heads for the borehole, across a range of depths, were estimated from the slug test measurements. Depth profiles of hydraulic head show rapid increases in hydraulic head with depth, in line with model predictions. Results show fluid pressures greatly exceeding hydrostatic pressure in the shallow crust, reflecting significant upward flow of groundwater beneath the Whataroa Valley. Hydraulic conductivity estimates provide constraints on the hydraulic conductivity structure of the region. All hydraulic conductivity structures modelled thus far

  2. Assessment of Climate Change Impacts on Flood Event Types in Two Alpine Catchments

    NASA Astrophysics Data System (ADS)

    Turkington, T.; Breinl, K.; Jetten, V.; Ettema, J.

    2014-12-01

    A variety of different climate factors can trigger floods: intense rainfall, long lasting rainfall or extreme amount of snowmelt. As a result, changes in climate extremes can affect both the frequency of floods, but also other factors such as seasonality and duration, all of which have implications on local social and ecological systems. Therefore, we present a technique for examining projected changes in flood events types, focusing on antecedent meteorological conditions. Floods (characterized by the historical 10 and 25-year return level discharge) are clustered into causal types based on rainfall, antecedent precipitation and temperature. A multi-site weather generator coupled with a conceptual rainfall-runoff model is employed to increase the number of flood events. Quantile mapping of precipitation and temperature projections is then used in the development of future discharge. The technique is applied to two different catchments in the European Alps: a smaller catchment in the southern French Alps, dominated by rain-on-snow floods, and a larger catchment in Austria, with more floods during summer. The results show that changes in precipitation and temperature can alter not only the frequency, but also the distribution of flood event types in the future. Furthermore, assessing changes in flood event types provides information about why the frequency of floods in an alpine catchment may change, even if the projections themselves are highly uncertain.

  3. Does allochthony in lakes change across an elevation gradient?.

    PubMed

    Rose, Kevin C; Williamson, Craig E; Kissman, Carrie E H; Saros, Jasmine E

    2015-12-01

    Ecosystems are subsidized with inputs of mass and energy from their surroundings. These allochthonous inputs regulate many ecosystem characteristics. In inland waters, terrestrial inputs of organic matter regulate food-web structure, ecosystem metabolism, water clarity, and thermal stratification. Future changes in allochthony may be especially pronounced in high-elevation ecosystems due to increases in vegetation and precipitation associated with climate change. Several techniques exist to characterize the degree of allochthony of organic matter in aquatic systems, including metrics such as ΔH, the net isotopic discrimination between water and particulate organic matter (POM) of deuterium stable isotopes, and the fluorescence index (FI), which characterizes the fluorescence of dissolved organic matter (DOM). Despite the importance of allochthonous organic carbon inputs, little is known about either how allochthony varies across elevation gradients or whether different metrics are similarly related to allochthony. We measured AH, FI, and a suite of related water-quality characteristics in 30 lakes across a montane to alpine elevation gradient (2340 to 3205 m) in the Beartooth Mountains of Montana and Wyoming, USA, to understand how FI and AH varied with elevation, with one another, and with other allochthony-related water-quality characteristics. We hypothesized that allochthony of POM and DOM would decrease at higher elevations, with alpine lakes above treeline being more autochthonous compared with low-elevation lakes below treeline. We observed a significant inverse linear relationship between AH and Fl, with both metrics indicating a decrease in allochthony at higher elevations. Characteristics including the natural log of the ratio of concentrations of dissolved organic carbon to chlorophyll a (ln(DOC: Chl)), the spectral slope ratio between different spectra of two wavebands (SR, ratio of spectra at 275-295 to 350-400 nm), and a ratio of diffuse attenuation

  4. View of Lake Sabrina Dam and Lake Sabrina from east ...

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

    View of Lake Sabrina Dam and Lake Sabrina from east ridge showing spillway at photo center, view southwest - Bishop Creek Hydroelectric System, Plant 2, Lake Sabrina Dam, Bishop Creek, Bishop, Inyo County, CA

  5. Lake sediment records as earthquake catalogues: A compilation from Swiss lakes - Limitations and possibilities

    NASA Astrophysics Data System (ADS)

    Kremer, Katrina; Reusch, Anna; Wirth, Stefanie B.; Anselmetti, Flavio S.; Girardclos, Stéphanie; Strasser, Michael

    2016-04-01

    Intraplate settings are characterized by low deformation rates and recurrence intervals of strong earthquakes that often exceed the time span covered by instrumental records. Switzerland, as an example for such settings, shows a low instrumentally recorded seismicity, in contrast to strong earthquakes (e.g. 1356 Basel earthquake, Mw=6.6 and 1601 Unterwalden earthquake, Mw=5.9) mentioned in the historical archives. As such long recurrence rates do not allow for instrumental identification of earthquake sources of these strong events, and as intense geomorphologic alterations prevent preservation of surface expressions of faults, the knowledge of active faults is very limited. Lake sediments are sensitive to seismic shaking and thus, can be used to extend the regional earthquake catalogue if the sedimentary deposits or deformation structures can be linked to an earthquake. Single lake records allow estimating local intensities of shaking while multiple lake records can furthermore be used to compare temporal and spatial distribution of earthquakes. In this study, we compile a large dataset of dated sedimentary event deposits recorded in Swiss lakes available from peer-reviewed publications and unpublished master theses. We combine these data in order to detect large prehistoric regional earthquake events or periods of intense shaking that might have affected multiple lake settings. In a second step, using empirical seismic attenuation equations, we test if lake records can be used to reconstruct magnitudes and epicentres of identified earthquakes.

  6. Of Microbes and Men: Determining Sources of Nitrate in Surface Waters of an Alpine Basin in the Colorado Front Range

    NASA Astrophysics Data System (ADS)

    Hafich, K. A.; Williams, M. W.; Savarino, J. P.

    2012-12-01

    High elevation ecosystems throughout the Colorado Front Range are undergoing changes in biogeochemical cycling due to an increase in nitrogen deposition in precipitation and a changing climate, resulting in changes in alpine biota and water quality. Between 1985 to 2009, nitrate concentrations in the outflow of Green Lakes 4 (GL4), at the headwaters of Boulder Creek, have increased 0.27 μmol/L per year, yet the question remains whether the primary source of increasing nitrate in Green Lakes Valley (GLV) is atmospheric or terrestrial. Previous research in the GL4 catchment suggests that nitrification in barren soils, talus and rock glaciers, not atmospheric deposition, is the primary source of nitrate in surface waters. Additionally, increasing nitrate levels could be attributed to melting ice features—permafrost and a rock glacier—in GLV, associated with increasing hydrologic connectivity. Coinciding with climatic changes (drought), the nitrate-N yield of the GL4 catchment increased by 40%, from a mean of 1.7 to 2.3 kg N/ha/yr between the periods 1985-1999 and 2000-2009. During the dry period, 2000-2009, noticeably high nitrate concentrations were recorded from the rock glacier above GL4 of up to 135 μmol/L, as well as high concentrations in talus runoff of up to 94 μmol/L. A synoptic survey of talus streams from summer 2012 showed similar results, with a maximum nitrate concentration of 84 μmol/L and a mean concentration of 33 μmol/L. We aim to characterize nitrate pathways in GLV with an analysis of triple oxygen isotopes of the nitrate molecule, a new method that allows us to discriminate whether nitrate in surface waters is from atmospheric deposition or produced by nitrification by microbial communities. Samples were collected weekly throughout summer 2012 from surface streams, talus streams, snowpack, snowmelt, groundwater wells, soil water and precipitation. High nitrate concentration values found in GLV are consistent with carbon limitation in

  7. Jurassic Lake T'oo'dichi': a large alkaline, saline lake, Morrison Formation, eastern Colorado Plateau

    USGS Publications Warehouse

    Turner, C.E.; Fishman, N.S.

    1991-01-01

    Recognition of alkaline, saline-lake deposits in the Morrison Formation significantly alters interpretations of depositional environments of this formation, and it also has important implications for paleoclimatic interpretation. Late Jurassic climate was apparently much more arid than had previously been thought. In fact, sedimentologic evidence suggests that the lake basin was typically dry for extended periods and enjoyed only brief wet intervals. This conclusion has important consequences for environmental interpretation of the habitat that was favorable for large herbivorous dinosaurs, which thrived in the Late Jurassic. -from Authors

  8. Sediment analysis to support the recent glacial origin of DDT pollution in Lake Iseo (Northern Italy).

    PubMed

    Bettinetti, Roberta; Galassi, Silvana; Guilizzoni, Piero; Quadroni, Silvia

    2011-09-01

    In the present study, a depth-related distribution of Persistent Organic Pollutants (POPs) in sediments of Lake Iseo, one of the major southern Alpine Italian lakes, is reported in order to further test the hypothesis of melting Alpine glaciers as a secondary source of contamination. In a previous paper, a "glacier contamination hypothesis" was suggested to explain the unexpected contamination of the biota of Lake Iseo, mainly fed by the Alpine melting ice. The sediment core analyses covered around the last 50 years. The organic matter profile evaluated as a Loss-On-Ignition percentage indicated transition of the basin from an oligotrophic to a mesotrophic status at around the early 1970s, but there was no evidence of the shift to eutrophy in the 1980s. Among DDTs, pp'DDE was the predominant metabolite, accounting on average for 79.4% of the total DDT concentrations and ranging from 6.4 to 447.5 ng g(-1)d.w. PCBs ranged from 5.0 to 163.7 ng g(-1)d.w. The maximum PCB concentrations were found in sediment layers corresponding to the 1970s when the highest production and use of these compounds occurred in Italy. In contrast, concentrations of DDTs showed a sharp increase from the early 1990s, long after their agricultural use was banned in Italy. This delayed pollution provides support for the hypothesis that the recent retreat of glaciers represents a secondary pollution source for old pesticides that were stored in the ice at the time of their use in agriculture. PMID:21724223

  9. Estimation of alpine skier posture using machine learning techniques.

    PubMed

    Nemec, Bojan; Petrič, Tadej; Babič, Jan; Supej, Matej

    2014-01-01

    High precision Global Navigation Satellite System (GNSS) measurements are becoming more and more popular in alpine skiing due to the relatively undemanding setup and excellent performance. However, GNSS provides only single-point measurements that are defined with the antenna placed typically behind the skier's neck. A key issue is how to estimate other more relevant parameters of the skier's body, like the center of mass (COM) and ski trajectories. Previously, these parameters were estimated by modeling the skier's body with an inverted-pendulum model that oversimplified the skier's body. In this study, we propose two machine learning methods that overcome this shortcoming and estimate COM and skis trajectories based on a more faithful approximation of the skier's body with nine degrees-of-freedom. The first method utilizes a well-established approach of artificial neural networks, while the second method is based on a state-of-the-art statistical generalization method. Both methods were evaluated using the reference measurements obtained on a typical giant slalom course and compared with the inverted-pendulum method. Our results outperform the results of commonly used inverted-pendulum methods and demonstrate the applicability of machine learning techniques in biomechanical measurements of alpine skiing. PMID:25313492

  10. In Review (Geology): Alpine Landscape Evolution Dominated by Cirque Retreat

    NASA Technical Reports Server (NTRS)

    Oskin, Michael; Burbank, Doug

    2005-01-01

    Despite the abundance in alpine terrain of glacially dissected landscapes, the magnitude and geometry of glacial erosion can rarely be defined. In the eastern Kyrgyz Range, a widespread unconformity exhumed as a geomorphic surface provides a regional datum with which to calibrate erosion. As tectonically driven surface uplift has progressively pushed this surface into the zone of ice accumulation, glacial erosion has overprinted the landscape. With as little as 500 m of incision into rocks underlying the unconformity, distinctive glacial valleys display their deepest incision adjacent to cirque headwalls. The expansion of north-facing glacial cirques at the expense of south-facing valleys has driven the drainage divide southwards at rates up to 2 to 3 times the rate of valley incision. Existing ice-flux-based glacial erosion rules incompletely model expansion of glacial valleys via cirque retreat into the low-gradient unconformity remnants. Local processes that either directly sap cirque headwalls or inhibit erosion down-glacier appear to control, at least initially, alpine landscape evolution.

  11. Estimation of Alpine Skier Posture Using Machine Learning Techniques

    PubMed Central

    Nemec, Bojan; Petrič, Tadej; Babič, Jan; Supej, Matej

    2014-01-01

    High precision Global Navigation Satellite System (GNSS) measurements are becoming more and more popular in alpine skiing due to the relatively undemanding setup and excellent performance. However, GNSS provides only single-point measurements that are defined with the antenna placed typically behind the skier's neck. A key issue is how to estimate other more relevant parameters of the skier's body, like the center of mass (COM) and ski trajectories. Previously, these parameters were estimated by modeling the skier's body with an inverted-pendulum model that oversimplified the skier's body. In this study, we propose two machine learning methods that overcome this shortcoming and estimate COM and skis trajectories based on a more faithful approximation of the skier's body with nine degrees-of-freedom. The first method utilizes a well-established approach of artificial neural networks, while the second method is based on a state-of-the-art statistical generalization method. Both methods were evaluated using the reference measurements obtained on a typical giant slalom course and compared with the inverted-pendulum method. Our results outperform the results of commonly used inverted-pendulum methods and demonstrate the applicability of machine learning techniques in biomechanical measurements of alpine skiing. PMID:25313492

  12. Flower color influences insect visitation in alpine New Zealand.

    PubMed

    Campbell, Diane R; Bischoff, Mascha; Lord, Janice M; Robertson, Alastair W

    2010-09-01

    Despite a long-standing belief that insect pollinators can select for certain flower colors, there are few experimental demonstrations that free-flying insects choose between natural flowers based on color. We investigated responses of insect visitors to experimental manipulations of flower color in the New Zealand alpine. Native syrphid flies (Allograpta and Platycheirus) and solitary bees (Hylaeus and Leioproctus) showed distinct preferences for visiting certain flower species. These responses were determined, in part, by flower color, as insects also responded to experimental manipulations of visible petal color in 7 out of 11 tests with different combinations of flower species and insect type. When preferences were detected, syrphid flies chose yellow over white petals regardless of flower species, whereas Hylaeus chose white over yellow Ourisia glandulosa. In some cases, the strength and direction of color preference depended on the context of other floral traits, in which case the response usually favored the familiar, normal combination of traits. Syrphid flies also visited in response to floral morphological traits but did not show preference based on UV reflectance. The unusually high preponderance of white flowers in the New Zealand alpine is not explained by complete generalization of flower color choice. Instead, the insect visitors show preferences based on color, including colors other than white, along with other floral traits. Furthermore, they can respond in complex ways to combinations of floral cues, suggesting that traits may act in nonadditive ways in determining pollinator visitation. PMID:20957958

  13. Climate Forced Alpine Tundra Ecosystem Dynamics: A Model Approach

    NASA Astrophysics Data System (ADS)

    Jarosch, A. H.; Clarke, G. K.; Danby, R. K.; Hik, D. S.

    2007-12-01

    Insights concerning the future evolution of alpine ecosystems depend on understanding and simulating their response to climate change. Comprehensive studies of these regions require novel spatio-temporal computational models of climate-forced landscape/ecosystem interactions. As part of the International Polar Year (IPY) we are examining alpine tundra landscapes and ecosystems in the Kluane region of southwest Yukon, Canada. Based on the combination of long-term geophysical and ecological field studies and driven by different climate change scenarios, such a model is being used to explore the range of possible future scenarios for the region. As the first step in building such a complex model, we present a simplified, grid-based model to demonstrate potential changes in plant community distribution driven by key climate variables such as temperature and precipitation. A linear orographic precipitation model is used to downscale climate data which, in combination with a digital elevation model, forms the geophysical input for the model. Simplified ecological rules describing the potential state transition of different plant communities and land cover types are incorporated in the model in a cellular automation fashion. The response of the ecosystem to several different climate scenarios will be presented, including a set of North American Regional Reanalysis climate data. This simplified model is used to demonstrate the potential of such interdisciplinary simulations to gain deeper understanding of ecosystem evolution with climate change.

  14. [Ecomorphological explanations of passerines coexistence i