Water, Energy, and Biogeochemical Budgets (WEBB): Loch Vale Watershed Completed
Loch Vale is an alpine/subalpine watershed in Rocky Mountain National Park where the U.S. Geological Survey has been conducting research since the 1980s. Our research has focused on the effects of climate change and atmospheric pollutants on water, soil, vegetation, and aquatic life. The alpine/subalpine ecosystem in Loch Vale is sensitive to changes in climate and air pollution. Our long-term data sets have allowed us to see how changes in climate affect glaciers, permafrost, and streamflow. It also has allowed us to see how atmospheric pollution affect water chemistry and biota.
Climate Change
Climate change studies in Loch Vale have documented increasing air temperatures, earlier snowmelt, and earlier runoff. These changes may have important impacts on water availability, water quality, and ecosystem function.
Water Resources
High-elevation and high-latitude watersheds in North America receive the majority of their annual precipitation as winter and spring snow [Serreze et al., 1999]. Most of this snow accumulates in seasonal snowpacks, which represent a natural storage reservoir whose size exceeds that of manmade reservoirs in many river basins of the world [Mote, 2006; Nijssen et al., 2001]. Arid regions, such as western United States, that receive relatively little precipitation during summer months are heavily dependent on natural and manmade storage to provide water for agriculture, industry, and drinking during the dry summer and fall seasons [Barnett et al., 2005].
Loch Vale typically receives 70-80% of annual precipitation in the form of snow; investigation of hydroclimatic processes that influence the timing of snowmelt is an important area of research. Recently, WEBB researchers used a new statistical method, the Regional Kendall Test (RKT), to document changes in the timing of snowmelt and streamflow runoff in Loch Vale and elsewhere in Colorado [Clow, submitted 2008]. Snowmelt and streamflow are occurring approximately two weeks earlier now than in the late 1970s, and the changes were positively correlated with increasing springtime air temperatures, and negatively correlated with maximum snow water content of the snowpack [Clow, submitted 2008]. Use of the RKT allowed identificaton of trends that had previously gone undetected due to large interannual variability and the relatively short period of record of the SNOTEL data sets [Stewart et al., 2005].
Analyses of temporal and spatial variations in the depth and water content of seasonal snowpacks was another area of extensive research at the Loch Vale WEBB site. Spatial variations in snowpack depth and water content were monitored starting in 1991 through the WEBB program, permitting development of snowpack distribution models using a combination of binary decision tree and geostatistical techniques [Balk and Elder, 2000; Cline, 1995]. Using data from Loch Vale and 65 additional sites, the methods have been applied to the Rocky Mountain region, and solute chemistry was added to the analysis to develop maps of nitrogen, sulfur, and acidity deposition in snow [Nanus et al., 2003]. Long-term, repeat sampling at these sites permitted an evaluation of temporal trends in solute deposition that accounted for climate variability [Ingersoll et al., 2008]. This allowed separation of trends attributable to climate versus those due to variations in nitrogen and sulfur emissions [Ingersoll et al., 2008].
Analysis of streamflow records for climate-induced trends in cold climates had hampered by the poor quality of discharge records during winter months, which is due to the presence of in-channel ice that causes variable backwater conditions and alters the stage-discharge relationship. WEBB research contributed to the recent development of an automated dye-dilution gaging system, which can provide high-quality, real-time discharge data at 8 hour intervals in ice-affected streams [Clow and Fleming, 2008].
Carbon Cycling
Carbon cycling has been studied in Loch Vale since the 1980s. Research indicated that wetlands in Loch Vale are now releasing more carbon than they are storing, and respiration occurs even during winter through deep snowpacks.
Landscapes at northern latitudes and high elevations account for a significant percentage of the Earth's land surface. Soils in many of these landscapes have been identified as important sources and sinks of atmospheric CO2 that maybe particularly sensitive to climate change [Oechel et al., 1997] Wetlands are the largest natural source of CH4 to the atmosphere, and northern and high-elevation wetlands may account for a third of this natural source [Moosavi and Crill, 1996]. Understanding of carbon sources and sinks in these landscape types is needed to reduce uncertainties about the North American carbon budget and underlying processes controlling carbon dynamics.
As much as half of northern latitude and high-elevation landscapes are snow covered for most of the year; yet, most attention has been focused on soil gas emissions in these environments during the growing season. Mast et al. [1998] measured CO2 and CH4 fluxes through snowpacks in Loch Vale to investigate processes controlling the exchange of gas between the soil and atmosphere during winter. The snowpack insulated soils from cold midwinter air temperatures allowing microbial activity to continue through the winter. Subalpine soils were net sources of CO2 through the winter, whereas saturated soils were net emitters of CH4 and dry soils were net CH4 consumers. Winter accounted for 8 to 23% of annual soil CO2 flux and 12 to 58% of the CH4 flux. These results indicate that soil gas fluxes during winter are significant and should be included in annual carbon budgets for seasonally snow-covered terrains.
Wickland et al. [1999; 2001] expanded this research by developing annual budgets for gas exchange in a subalpine wetland system in Loch Vale. Annual respiration and CH4 emission were modeled by applying the flux-temperature relationships to a continuous soil temperature record. Gross photosynthesis was modeled using a hyperbolic equation relating gross photosynthesis, photon flux density, and soil temperature. Modeled annual flux estimates indicate that the wetland was a net source of carbon gas to the atmosphere during the 3-year study period. This contrasts with estimates from an age-dated peat core, which indicate the wetland has been a sink of carbon for the past 7,100 years. Wickland et al. [2001] suggested the switch from sink to source may indicate these wetland systems are sensitive to even minor variations in climate.
Mineral Weathering
Mineral weathering is a natural process that occurs in soil and helps neutralize acid rain. Thin, patchy soils in Loch Vale make this area sensitive to acid deposition. Mineral weathering also consumes atmospheric carbon dioxide, and over geologic time scales, it is the principal mechanism for regulating climate.
Solute fluxes in streams, which are the product of concentration times discharge, are strongly affected by variations in climate. Research in Loch Vale, subsequently confirmed at many other headwater catchments in the United States, has documented that concentrations of weathering products exhibit relatively little variability in relation to changes in precipitation, discharge, or annual runoff [Clow, 1992; Clow and Drever, 1996; Godsey et al., submitted 2008]. As a result, fluxes of weathering products increase almost in direct proportion to annual variations in precipitation. This has important implications for carbon budgets because weathering of silicate minerals in pristine catchments is driven primarily by carbonic-acid dissolution reactions, which consume CO2. Exploring the mechanisms for this "chemostatic" behavior is an area of active research for the WEBB program [Clow and Drever, 1996; Godsey et al., submitted 2008; White and Blum, 1995a; White and Blum, 1995b; White et al., 1999]. A hydrograph separation study by Mast [1995] using water isotopes and silica documented that fast reactions in the soil must play an important role. Dilution of weathering products during wet periods with concomitant increases in weathering rates also may be important [Drever and Clow, 1995].
In contrast to fluxes of weathering products, nitrogen fluxes in Loch Vale are not strongly related to annual precipitation amount [Campbell et al., 2000]. Currently, nitrogen assimilation in alpine terrain is limited by cold temperatures; however, increasing trends in air temperatures and lengthening growing seasons may increase nitrogen assimilation rates.
Nitrogen Deposition
Nitrogen emissions from automobiles, industry, and agriculture are transported to Loch Vale through the atmosphere. When deposited on vegetation, soil, and water, excess nitrogen can lead to increased nutrient concentrations in lakes and streams, and changes in the type and abundance of aquatic life and vegetation.
Mercury Deposition
Mercury is emitted to the atmosphere by a variety of natural processes and anthropogenic activities. Mercury deposition to alpine environments can be large, and is bioaccumulated in fish.
Groundwater in Alpine Terrain
Alpine/subalpine catchements like Loch Vale tend to have thin, patchy soils and little alluvial material. However, talus cones and permafrost may provide substantial underground storage capacity for water.
Permafrost
In a study of groundwater occurrence and contributions to streamflow in Loch Vale, it was determined that ice stored in permafrost (including rock glaciers) represented the second largest ground water reservoir in the basin [Clow et al., 2003b]. Rock glaciers were mapped and the depth to ice was measured using seismic refraction methods. The extent of potential permafrost was modeled based on remotely-sensed snow cover data and climatic data from the 3 weather stations in Loch Vale. Mean annual air temperatures (MATs) were sufficiently cold to support permafrost above 3460 m (50% of the watershed); however, MATs increased by 2.6°C between 1983 and 2007 [Clow, submitted 2008]. If other climatic factors remain constant, the increase in air temperatures at Loch Vale is sufficient to increase the lower elevational limit of permafrost by approximately 300 m [Clow et al., 2003b; Clow, submitted 2008]. Additional evidence for melting permafrost in Loch Vale is provided by unexpectedly long average transit times for water and sulfur, based on analyses of CFCs, sulfur-35 isotopes, and tritium [Clow et al., 2003a; Clow et al., 2005; Michel et al., 2000].
Earlier research in Loch Vale documented that glaciers contained water approximately equivalent to mean annual runoff for the basin [Ingersoll, 1995]. During drought conditions in 2002-2003, the runoff:precipitation ratio increased from approximately 0.7 to almost 1.0, suggesting that glacier and permafrost melt may have subsidized runoff during late summer [Baron et al., submitted 2008]. Melting glacial ice and permafrost has been implicated as a driving force for increasing nitrate concentrations in streams in Loch Vale [Baron et al., submitted 2008].
Below are other science projects related to this project.
The Western Mountain Initiative (WMI)
Water, Energy, and Biogeochemical Budgets (WEBB): Loch Vale Data
The chemistry of streams and lakes have been monitored in Loch Vale since 1983. Changes in stream and lake chemistry have been traced to variations in climate and atmospheric deposition of pollutants. Samples are collected throughout the year in Loch Vale. This provides information on seasonal variations in stream and lake chemistry.
Below are multimedia items associated with this project.
Below are publications associated with this project.
Changes in the chemistry of lakes and precipitation in high-elevation national parks in the western United States, 1985–1999
Hatching success in salamanders and chorus frogs at two sites in Colorado, USA: Effects of acidic deposition and climate
Ground water occurrence and contributions to streamflow in an alpine catchment, Colorado Front Range
Chemistry of selected high-elevation lakes in seven national parks in the western United States
Use of natural 35S to trace sulphate cycling in small lakes, Flattops Wilderness Area, Colorado, U.S.A.
Pathways for nitrate release from an alpine watershed: Determination using δ15N and δ18O
Comparison of snowpack and winter wet-deposition chemistry in the Rocky Mountains, USA: Implications for winter dry deposition
Mercury loading and methylmercury production and cycling in high-altitude lakes from the Western United States
Effect of basin physical characteristics on solute fluxes in nine alpine/subalpine basins, Colorado, USA
Use of 17O/16O to trace atmospherically-deposited sulfate in surface waters: A case study in alpine watersheds in the Rocky Mountains
Use of stable sulfur isotopes to identify sources of sulfate in Rocky Mountain snowpacks
Carbon gas exchange at a southern Rocky Mountain wetland, 1996-1998
Below are partners associated with this project.
- Overview
Loch Vale is an alpine/subalpine watershed in Rocky Mountain National Park where the U.S. Geological Survey has been conducting research since the 1980s. Our research has focused on the effects of climate change and atmospheric pollutants on water, soil, vegetation, and aquatic life. The alpine/subalpine ecosystem in Loch Vale is sensitive to changes in climate and air pollution. Our long-term data sets have allowed us to see how changes in climate affect glaciers, permafrost, and streamflow. It also has allowed us to see how atmospheric pollution affect water chemistry and biota.
Climate Change
Climate change studies in Loch Vale have documented increasing air temperatures, earlier snowmelt, and earlier runoff. These changes may have important impacts on water availability, water quality, and ecosystem function.
Water Resources
High-elevation and high-latitude watersheds in North America receive the majority of their annual precipitation as winter and spring snow [Serreze et al., 1999]. Most of this snow accumulates in seasonal snowpacks, which represent a natural storage reservoir whose size exceeds that of manmade reservoirs in many river basins of the world [Mote, 2006; Nijssen et al., 2001]. Arid regions, such as western United States, that receive relatively little precipitation during summer months are heavily dependent on natural and manmade storage to provide water for agriculture, industry, and drinking during the dry summer and fall seasons [Barnett et al., 2005].
Loch Vale typically receives 70-80% of annual precipitation in the form of snow; investigation of hydroclimatic processes that influence the timing of snowmelt is an important area of research. Recently, WEBB researchers used a new statistical method, the Regional Kendall Test (RKT), to document changes in the timing of snowmelt and streamflow runoff in Loch Vale and elsewhere in Colorado [Clow, submitted 2008]. Snowmelt and streamflow are occurring approximately two weeks earlier now than in the late 1970s, and the changes were positively correlated with increasing springtime air temperatures, and negatively correlated with maximum snow water content of the snowpack [Clow, submitted 2008]. Use of the RKT allowed identificaton of trends that had previously gone undetected due to large interannual variability and the relatively short period of record of the SNOTEL data sets [Stewart et al., 2005].
Analyses of temporal and spatial variations in the depth and water content of seasonal snowpacks was another area of extensive research at the Loch Vale WEBB site. Spatial variations in snowpack depth and water content were monitored starting in 1991 through the WEBB program, permitting development of snowpack distribution models using a combination of binary decision tree and geostatistical techniques [Balk and Elder, 2000; Cline, 1995]. Using data from Loch Vale and 65 additional sites, the methods have been applied to the Rocky Mountain region, and solute chemistry was added to the analysis to develop maps of nitrogen, sulfur, and acidity deposition in snow [Nanus et al., 2003]. Long-term, repeat sampling at these sites permitted an evaluation of temporal trends in solute deposition that accounted for climate variability [Ingersoll et al., 2008]. This allowed separation of trends attributable to climate versus those due to variations in nitrogen and sulfur emissions [Ingersoll et al., 2008].
Analysis of streamflow records for climate-induced trends in cold climates had hampered by the poor quality of discharge records during winter months, which is due to the presence of in-channel ice that causes variable backwater conditions and alters the stage-discharge relationship. WEBB research contributed to the recent development of an automated dye-dilution gaging system, which can provide high-quality, real-time discharge data at 8 hour intervals in ice-affected streams [Clow and Fleming, 2008].Carbon Cycling
Carbon cycling has been studied in Loch Vale since the 1980s. Research indicated that wetlands in Loch Vale are now releasing more carbon than they are storing, and respiration occurs even during winter through deep snowpacks.
Landscapes at northern latitudes and high elevations account for a significant percentage of the Earth's land surface. Soils in many of these landscapes have been identified as important sources and sinks of atmospheric CO2 that maybe particularly sensitive to climate change [Oechel et al., 1997] Wetlands are the largest natural source of CH4 to the atmosphere, and northern and high-elevation wetlands may account for a third of this natural source [Moosavi and Crill, 1996]. Understanding of carbon sources and sinks in these landscape types is needed to reduce uncertainties about the North American carbon budget and underlying processes controlling carbon dynamics.
As much as half of northern latitude and high-elevation landscapes are snow covered for most of the year; yet, most attention has been focused on soil gas emissions in these environments during the growing season. Mast et al. [1998] measured CO2 and CH4 fluxes through snowpacks in Loch Vale to investigate processes controlling the exchange of gas between the soil and atmosphere during winter. The snowpack insulated soils from cold midwinter air temperatures allowing microbial activity to continue through the winter. Subalpine soils were net sources of CO2 through the winter, whereas saturated soils were net emitters of CH4 and dry soils were net CH4 consumers. Winter accounted for 8 to 23% of annual soil CO2 flux and 12 to 58% of the CH4 flux. These results indicate that soil gas fluxes during winter are significant and should be included in annual carbon budgets for seasonally snow-covered terrains.
Wickland et al. [1999; 2001] expanded this research by developing annual budgets for gas exchange in a subalpine wetland system in Loch Vale. Annual respiration and CH4 emission were modeled by applying the flux-temperature relationships to a continuous soil temperature record. Gross photosynthesis was modeled using a hyperbolic equation relating gross photosynthesis, photon flux density, and soil temperature. Modeled annual flux estimates indicate that the wetland was a net source of carbon gas to the atmosphere during the 3-year study period. This contrasts with estimates from an age-dated peat core, which indicate the wetland has been a sink of carbon for the past 7,100 years. Wickland et al. [2001] suggested the switch from sink to source may indicate these wetland systems are sensitive to even minor variations in climate.
Mineral Weathering
Mineral weathering is a natural process that occurs in soil and helps neutralize acid rain. Thin, patchy soils in Loch Vale make this area sensitive to acid deposition. Mineral weathering also consumes atmospheric carbon dioxide, and over geologic time scales, it is the principal mechanism for regulating climate.
Solute fluxes in streams, which are the product of concentration times discharge, are strongly affected by variations in climate. Research in Loch Vale, subsequently confirmed at many other headwater catchments in the United States, has documented that concentrations of weathering products exhibit relatively little variability in relation to changes in precipitation, discharge, or annual runoff [Clow, 1992; Clow and Drever, 1996; Godsey et al., submitted 2008]. As a result, fluxes of weathering products increase almost in direct proportion to annual variations in precipitation. This has important implications for carbon budgets because weathering of silicate minerals in pristine catchments is driven primarily by carbonic-acid dissolution reactions, which consume CO2. Exploring the mechanisms for this "chemostatic" behavior is an area of active research for the WEBB program [Clow and Drever, 1996; Godsey et al., submitted 2008; White and Blum, 1995a; White and Blum, 1995b; White et al., 1999]. A hydrograph separation study by Mast [1995] using water isotopes and silica documented that fast reactions in the soil must play an important role. Dilution of weathering products during wet periods with concomitant increases in weathering rates also may be important [Drever and Clow, 1995].
In contrast to fluxes of weathering products, nitrogen fluxes in Loch Vale are not strongly related to annual precipitation amount [Campbell et al., 2000]. Currently, nitrogen assimilation in alpine terrain is limited by cold temperatures; however, increasing trends in air temperatures and lengthening growing seasons may increase nitrogen assimilation rates.
Nitrogen Deposition
Nitrogen emissions from automobiles, industry, and agriculture are transported to Loch Vale through the atmosphere. When deposited on vegetation, soil, and water, excess nitrogen can lead to increased nutrient concentrations in lakes and streams, and changes in the type and abundance of aquatic life and vegetation.
Mercury Deposition
Mercury is emitted to the atmosphere by a variety of natural processes and anthropogenic activities. Mercury deposition to alpine environments can be large, and is bioaccumulated in fish.
Groundwater in Alpine Terrain
Alpine/subalpine catchements like Loch Vale tend to have thin, patchy soils and little alluvial material. However, talus cones and permafrost may provide substantial underground storage capacity for water.
Permafrost
In a study of groundwater occurrence and contributions to streamflow in Loch Vale, it was determined that ice stored in permafrost (including rock glaciers) represented the second largest ground water reservoir in the basin [Clow et al., 2003b]. Rock glaciers were mapped and the depth to ice was measured using seismic refraction methods. The extent of potential permafrost was modeled based on remotely-sensed snow cover data and climatic data from the 3 weather stations in Loch Vale. Mean annual air temperatures (MATs) were sufficiently cold to support permafrost above 3460 m (50% of the watershed); however, MATs increased by 2.6°C between 1983 and 2007 [Clow, submitted 2008]. If other climatic factors remain constant, the increase in air temperatures at Loch Vale is sufficient to increase the lower elevational limit of permafrost by approximately 300 m [Clow et al., 2003b; Clow, submitted 2008]. Additional evidence for melting permafrost in Loch Vale is provided by unexpectedly long average transit times for water and sulfur, based on analyses of CFCs, sulfur-35 isotopes, and tritium [Clow et al., 2003a; Clow et al., 2005; Michel et al., 2000].
Earlier research in Loch Vale documented that glaciers contained water approximately equivalent to mean annual runoff for the basin [Ingersoll, 1995]. During drought conditions in 2002-2003, the runoff:precipitation ratio increased from approximately 0.7 to almost 1.0, suggesting that glacier and permafrost melt may have subsidized runoff during late summer [Baron et al., submitted 2008]. Melting glacial ice and permafrost has been implicated as a driving force for increasing nitrate concentrations in streams in Loch Vale [Baron et al., submitted 2008]. - Science
Below are other science projects related to this project.
The Western Mountain Initiative (WMI)
Western Mountain Initiative (WMI) is a long-term collaboration between FORT, WERC, NOROCK, USFS, NPS, LANL, and universities worldwide to address changes in montane forests and watersheds due to climate change. Current emphases include altered forest disturbance regimes (fire, die-off, insect outbreaks) and hydrology; interactions between plants, water, snow, nutrient cycles, and climate; and... - Data
Water, Energy, and Biogeochemical Budgets (WEBB): Loch Vale Data
The chemistry of streams and lakes have been monitored in Loch Vale since 1983. Changes in stream and lake chemistry have been traced to variations in climate and atmospheric deposition of pollutants. Samples are collected throughout the year in Loch Vale. This provides information on seasonal variations in stream and lake chemistry.
- Multimedia
Below are multimedia items associated with this project.
- Publications
Below are publications associated with this project.
Filter Total Items: 60Changes in the chemistry of lakes and precipitation in high-elevation national parks in the western United States, 1985–1999
High-elevation lakes in the western United States are sensitive to atmospheric deposition of sulfur and nitrogen due to fast hydrologic flushing rates, short growing seasons, an abundance of exposed bedrock, and a lack of well-developed soils. This sensitivity is reflected in the dilute chemistry of the lakes, which was documented in the U.S. Environmental Protection Agency's Western Lake Survey oAuthorsDavid W. Clow, James O. Sickman, Robert G. Striegl, David P. Krabbenhoft, John G. Elliott, Mark M. Dornblaser, David A. Roth, Donald H. CampbellHatching success in salamanders and chorus frogs at two sites in Colorado, USA: Effects of acidic deposition and climate
The snowpack in the vicinity of the Mount Zirkel Wilderness Area is among the most acidic in the western United States. We analyzed water chemistry and examined hatching success in tiger salamanders and chorus frogs at ponds there and at nearby Rabbit Ears Pass (Dumont) to determine whether acid deposition affects amphibians or their breeding habitats at these potentially sensitive locations. We fAuthorsE. Muths, K. Campbell, P. S. CornGround water occurrence and contributions to streamflow in an alpine catchment, Colorado Front Range
Ground water occurrence, movement, and its contribution to streamflow were investigated in Loch Vale, an alpine catchment in the Front Range of the Colorado Rocky Mountains. Hydrogeomorphologic mapping, seismic refraction measurements, and porosity and permeability estimates indicate that talus slopes are the primary ground water reservoir, with a maximum storage capacity that is equal to, or greaAuthorsD. W. Clow, L. Schrott, R. Webb, K. Campbell, A.O. Torizzo, M. DornblaserChemistry of selected high-elevation lakes in seven national parks in the western United States
A chemical survey of 69 high-altitude lakes in seven national parks in the western United States was conducted during the fallof 1999; the lakes were previously sampled during the fall of 1985, as part of the Western Lake Survey. Lakes in parks in the Sierra/southern Cascades (Lassen Volcanic, Yosemite, Sequoia/Kings Canyon National Parks) and in the southern RockyMountains (Rocky Mountain NationaAuthorsDavid W. Clow, Robert G. Striegl, Leora Nanus, Alisa Mast, Donald H. Campbell, David P. KrabbenhoftUse of natural 35S to trace sulphate cycling in small lakes, Flattops Wilderness Area, Colorado, U.S.A.
Measurements of the cosmogenically-produced 35S, a radioisotope of sulphur (t1/2 = 87 days), are reported for the Ned Wilson Lake watershed in Colorado. The watershed contains two small lakes and a flowing spring presumed to be representative of local ground water. The watershed is located in the Flattops Wilderness Area and the waters in the system have low alkalinity, making them sensitive to inAuthorsRobert L. Michel, John T. Turk, Donald H. Campbell, Alisa MastPathways for nitrate release from an alpine watershed: Determination using δ15N and δ18O
Snowpack, snowmelt, precipitation, surface water, and groundwater samples from the Loch Vale watershed in Colorado were analyzed for δ15N and δ18O of nitrate to determine the processes controlling the release of atmospherically deposited nitrogen from alpine and subalpine ecosystems. Although overlap was found between the δ15N(NO3) values for all water types (−4 to +6‰), the δ18O(NO3) values for sAuthorsDonald H. Campbell, Carol Kendall, Cecily C.Y. Chang, Steven R. Silva, Kathy A. TonnessenComparison of snowpack and winter wet-deposition chemistry in the Rocky Mountains, USA: Implications for winter dry deposition
Depth-integrated snowpack chemistry was measured just prior to maximum snowpack depth during the winters of 1992-1999 at 12 sites co-located with National Atmospheric Deposition Program/National Trend Network (NADP/NTN) sites in the central and southern Rocky Mountains, USA. Winter volume-weighted mean wet-deposition concentrations were calculated for the NADP/NTN sites, and the data were comparedAuthorsDavid W. Clow, George P. Ingersoll, Alisa Mast, John T. Turk, Donald H. CampbellMercury loading and methylmercury production and cycling in high-altitude lakes from the Western United States
Studies worldwide have shown that mercury (Hg) is a ubiquitous contaminant, reaching even the most remote environments such as high-altitude lakes via atmospheric pathways. However, very few studies have been conducted to assess Hg contamination levels of these systems. We sampled 90 mid-latitude, high-altitude lakes from seven national parks in the western United States during a four-week periodAuthorsDavid P. Krabbenhoft, Mark L. Olson, John F. DeWild, David W. Clow, Robert G. Striegl, Mark M. Dornblaser, Peter C. Van MetreEffect of basin physical characteristics on solute fluxes in nine alpine/subalpine basins, Colorado, USA
Alpine/subalpine basins may exhibit substantial variability in solute fluxes despite many apparent similarities in basin characteristics. An evaluation of controls on spatial patterns in solute fluxes may allow development of predictive tools for assessing basin sensitivity to outside perturbations such as climate change or deposition of atmospheric pollutants. Relationships between basin physicalAuthorsJ.K. Sueker, D. W. Clow, J. N. Ryan, R.D. JarrettUse of 17O/16O to trace atmospherically-deposited sulfate in surface waters: A case study in alpine watersheds in the Rocky Mountains
Building on the discovery of excess 17O in atmospheric sulfate by Lee et al. (2001), we have carried out a case study to determine whether 17O might provide a new tool for quantifying the impact of atmospheric deposition on surface-water sulfate loads. In Rocky Mountain alpine regions, excess 17O was found to be characteristics of atmospheric sulfate deposited in snow. Excess 17O was also evidentAuthorsC.A. Johnson, M.A. Mast, C.L. KesterUse of stable sulfur isotopes to identify sources of sulfate in Rocky Mountain snowpacks
Stable sulfur isotope ratios and major ions in bulk snowpack samples were monitored at a network of 52 high-elevation sites along and near the Continental Divide from 1993 to 1999. This information was collected to better define atmospheric deposition to remote areas of the Rocky Mountains and to help identify the major source regions of sulfate in winter deposition. Average annual ??34S values atAuthorsM.A. Mast, J.T. Turk, G.P. Ingersoll, D. W. Clow, C.L. KesterCarbon gas exchange at a southern Rocky Mountain wetland, 1996-1998
Carbon dioxide (CO2) and methane (CH4) exchange between the atmosphere and a subalpine wetland located in Rocky Mountain National Park, Colorado, at 3200 m elevation were measured during 1996-1998. Respiration, net CO2 flux, and CH4 flux were measured using the closed chamber method during snow-free periods and using gas diffusion calculations during snow-covered periods. The ranges of measured flAuthorsK.P. Wickland, Robert G. Striegl, M.A. Mast, D. W. Clow - Partners
Below are partners associated with this project.