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Huntington TG, Shanley JB. A systematic increase in the slope of the concentration discharge relation for dissolved organic carbon in a forested catchment in Vermont, USA. Sci Total Environ 2022; 844:156954. [PMID: 35760172 DOI: 10.1016/j.scitotenv.2022.156954] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Revised: 06/20/2022] [Accepted: 06/21/2022] [Indexed: 06/15/2023]
Abstract
The production, mobilization and fluvial transport of dissolved organic carbon (DOC) in temperate forests are important components of the carbon cycle that are influenced by ongoing changes in climate. Numerous studies have reported temporal trends in stream water DOC concentrations and have attributed changes in concentrations to climatic and hydrologic variables. Fewer studies have reported trends in concentration-discharge (C-Q) relations for DOC. The goal of this study was to detect and quantify changes in DOC concentration and slope of the C-Q relation from 1991 to 2018 in an intensively sampled forested research watershed in northern Vermont. Stream water DOC concentration and slope of the C-Q relation increased over time as did precipitation, stream discharge, and air temperature. The increases in DOC concentration and slope of the C-Q were substantially greater in the summer and fall (autumn) than in winter and spring. The largest increases in the magnitude of C-Q slopes occurred in the December, October and September. The increases in slope of the C-Q relation in summer and fall were larger for baseflow than for storm flow. The increases in DOC concentration and slope of the C-Q relation over time may be related to increasing temperature, longer growing seasons, and associated increases in production and microbial decomposition of soil organic matter that supplies DOC for mobilization to streams. The results suggest that in a changing climate, C-Q relations may not necessarily be stationary and therefore analyses that attempt to estimate future DOC concentrations and loads should consider potentially changing C-Q relations over time.
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Affiliation(s)
- Thomas G Huntington
- U. S. Geological Survey, New England Water Science Center, 196 Whitten Rd., Augusta, Maine 04330, USA.
| | - James B Shanley
- U. S. Geological Survey, New England Water Science Center, 87 State Street, Montpelier, VT 05602, USA
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2
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Ross DS, Bailey SW, Villars TR, Quintana A, Wilmot S, Shanley JB, Halman JM, Duncan JA, Bower JA. Long-term monitoring of Vermont's forest soils: early trends and efforts to address innate variability. Environ Monit Assess 2021; 193:776. [PMID: 34746965 DOI: 10.1007/s10661-021-09550-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 10/19/2021] [Indexed: 06/13/2023]
Abstract
Long-term monitoring of forest soils is necessary to understand the effects of continued environmental change, including climate change, atmospheric deposition of metals, and, in many regions, recovery from acidic precipitation. A monitoring program was initiated in 2002 at five protected forest sites, primarily Spodosol soils, in Vermont, northeastern USA. Every 5 years, ten soil pits were sampled from random subplots in a 50 × 50-m plot at each site. Samples were taken by genetic horizon and, to reduce variability and improve comparability, from four specific layers: the combined Oi/Oe layer, the combined Oa/A layer, the top 10 cm of the B horizon, and 60-70 cm below the soil surface (usually the C horizon). The samples were archived and a subset analyzed for carbon, nitrogen, and exchangeable cations. After four sampling campaigns, the average coefficients of variation (CVs) at each site had a broad range, 10.7% for carbon in the Oa/A horizon to 84.3% for exchangeable Ca2+ in the B horizon. An investigation of variability within the upper 10 cm of the B horizon across a 90-cm soil pit face showed similar CVs to the entire site, emphasizing the need for consistent and careful sampling. After 15 years, temporal trends were significant in the Oa/A and B horizons at two of the five sites, with one site showing an increase in carbon concentration in both layers along with increases in both exchangeable Ca2+ and Al3+ in the B horizon, perhaps linked to recovery from acidification. The monitoring program plans to continue at 5-year intervals for the next century.
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Affiliation(s)
- Donald S Ross
- Department of Plant & Soil Science, University of Vermont, Burlington, VT, USA.
| | - Scott W Bailey
- Northern Research Station, USDA Forest Service, North Woodstock, NH, USA
| | - Thomas R Villars
- USDA Natural Resource Conservation Service, White River Junction, VT, USA
| | - Angelica Quintana
- USDA Forest Service, Green Mountain and Finger Lakes National Forests, Rutland, VT, USA
| | - Sandy Wilmot
- Vermont Department of Forests, Parks & Recreation, Division of Forests, Essex Junction, VT, USA
| | | | - Joshua M Halman
- Vermont Department of Forests, Parks & Recreation, Division of Forests, Essex Junction, VT, USA
| | - James A Duncan
- Forest Ecosystem Monitoring Cooperative, South Burlington, VT, USA
| | - Jennifer A Bower
- Department of Plant & Soil Science, University of Vermont, Burlington, VT, USA
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3
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Shanley JB, Marvin-DiPasquale M, Lane O, Arendt W, Hall S, McDowell WH. Resolving a paradox-high mercury deposition, but low bioaccumulation in northeastern Puerto Rico. Ecotoxicology 2020; 29:1207-1220. [PMID: 31643013 DOI: 10.1007/s10646-019-02108-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 09/05/2019] [Indexed: 06/10/2023]
Abstract
At a "clean air" trade winds site in northeastern Puerto Rico, we found an apparent paradox: atmospheric total mercury (THg) deposition was highest of any site in the USA Mercury Deposition Network, but assimilation into the local food web was quite low. Avian blood THg concentrations (n = 31, from eight species in five foraging guilds) ranged widely from 0.2 to 32 ng g-1 (median of 4.3 ng g-1). Within this population, THg was significantly greater at a low-elevation site near a wetland compared to an upland montane site, even when the comparison was limited to a single species. Overall, however, THg concentrations were approximately an order of magnitude lower than comparable populations in the continental U.S. In surface soil and sediment, potential rates of demethylation were 3 to 9-fold greater than those for Hg(II)-methylation (based on six radiotracer amendment incubations), but rates of change of ambient MeHg pools showed a slight net positive Hg(II)-methylation. Thus, the resolution of the paradox is that MeHg degradation approximately keeps pace with MeHg production in this landscape. Further, any net production of MeHg is subject to frequent flushing by high rainfall on chronically wet soils. The interplay of these microbial processes and hydrology appears to shield the local food web from adverse effects of high atmospheric mercury loading. This scenario may play out in other humid tropical ecosystems as well, but it is difficult to evaluate because coordinated studies of Hg deposition, methylation, and trophic uptake have not been conducted at other tropical sites.
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Affiliation(s)
- James B Shanley
- U.S. Geological Survey, P.O. Box 628, Montpelier, VT, 05601, USA.
| | | | - Oksana Lane
- Biodiversity Research Institute, Portland, ME, USA
| | - Wayne Arendt
- USFS, International Institute of Tropical Forestry, Luquillo, PR, USA
| | - Steven Hall
- Department of Ecology and Evolutionary Biology, Iowa State University, Ames, IA, USA
| | - William H McDowell
- Department of Natural Resources and the Environment, University of New Hampshire, Durham, NH, USA
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4
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Bishop K, Shanley JB, Riscassi A, de Wit HA, Eklöf K, Meng B, Mitchell C, Osterwalder S, Schuster PF, Webster J, Zhu W. Recent advances in understanding and measurement of mercury in the environment: Terrestrial Hg cycling. Sci Total Environ 2020; 721:137647. [PMID: 32197286 DOI: 10.1016/j.scitotenv.2020.137647] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Revised: 02/23/2020] [Accepted: 02/28/2020] [Indexed: 06/10/2023]
Abstract
This review documents recent advances in terrestrial mercury cycling. Terrestrial mercury (Hg) research has matured in some areas, and is developing rapidly in others. We summarize the state of the science circa 2010 as a starting point, and then present the advances during the last decade in three areas: land use, sulfate deposition, and climate change. The advances are presented in the framework of three Hg "gateways" to the terrestrial environment: inputs from the atmosphere, uptake in food, and runoff with surface water. Among the most notable advances: These and other advances reported here are of value in evaluating the effectiveness of the Minamata Convention on reducing environmental Hg exposure to humans and wildlife.
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Affiliation(s)
- Kevin Bishop
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Box 7050, 75007 Uppsala, Sweden.
| | | | - Ami Riscassi
- Department of Environmental Sciences, University of Virginia, P.O. Box 400123, Charlottesville, VA 22904-4123, USA.
| | - Heleen A de Wit
- Norwegian Institute for Water Research, Gaustadalléen 21, NO-0349, Norway.
| | - Karin Eklöf
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Box 7050, 75007 Uppsala, Sweden.
| | - Bo Meng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China.
| | - Carl Mitchell
- Department of Physical and Environmental Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario M1C 1A4, Canada.
| | - Stefan Osterwalder
- Institut des Géosciences de l'Environnement, Université Grenoble Alpes, CNRS, IRD, Grenoble 18 INP, 38000 Grenoble, France.
| | - Paul F Schuster
- U.S. Geological Survey, 3215 Marine Street, Suite E-127, Boulder, CO 80303-1066, USA.
| | - Jackson Webster
- Department of Civil Engineering, California State University, 400 W. 1st Street, 21 95929-0930 Chico, CA, USA.
| | - Wei Zhu
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, 90183 Umeå, Sweden.
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5
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Navrátil T, Nováková T, Roll M, Shanley JB, Kopáček J, Rohovec J, Kaňa J, Cudlín P. Decreasing litterfall mercury deposition in central European coniferous forests and effects of bark beetle infestation. Sci Total Environ 2019; 682:213-225. [PMID: 31121348 DOI: 10.1016/j.scitotenv.2019.05.093] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 05/06/2019] [Accepted: 05/07/2019] [Indexed: 06/09/2023]
Abstract
We evaluated a 14-year trend (2003-2017) in mercury (Hg) concentrations and fluxes in six litterfall categories (needles, bark, twigs, cones, lichen, and a mixture of unidentified fragments) at six research plots situated in two central European unmanaged mountain forest stands, dominated by mature Norway spruce. One of the stands (catchment of Plešné Lake, PL) was infested by bark beetle and all mature spruces died at three of four research plots during the study. One PL plot and two plots in the second stand (catchment of Čertovo Lake, CT) were intact and used as a control. At the intact plots, the litterfall Hg deposition averaged 45 and 32 μg/m2/year in the PL and CT catchments, respectively, while bulk precipitation Hg deposition was an order of magnitude lower (2.6 μg/m2/year). In the individual litter categories, Hg concentrations averaged 223, 195, 126, 81, 79 and 30 μg/kg in lichen, unidentified fragments, bark, twigs, needles and cones, respectively. As a result of decreasing European Hg emissions, Hg concentrations in most litter categories decreased from 2003 to 2017. Consequently, the litter-associated Hg flux to the forest floor decreased from 66 to 23 μg/m2/year during 2003-2017. The litterfall mass fluxes exhibited no trends at the intact plots. In contrast, the litter-associated Hg flux increased 5-fold after tree dieback due to elevated litterfall, averaging 218 μg/m2/year Hg at the PL infested plots during 2004-2009. The relative contribution of individual litter categories to the total Hg flux shifted from needle to bark and twig dominance. Starting in 2010, Hg flux decreased to pre-disturbance levels for the following decade. The tree mortality in the PL catchment provided a unique opportunity to evaluate changes in litter-associated Hg fluxes to the forest floor during and after natural tree dieback.
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Affiliation(s)
- Tomáš Navrátil
- Institute of Geology of the Czech Academy of Sciences, Rozvojová 269, 165 00 Prague 6, Czech Republic.
| | - Tereza Nováková
- Institute of Geology of the Czech Academy of Sciences, Rozvojová 269, 165 00 Prague 6, Czech Republic
| | - Michal Roll
- Institute of Geology of the Czech Academy of Sciences, Rozvojová 269, 165 00 Prague 6, Czech Republic; Institute of Geochemistry, Mineralogy and Mineral Resources, Faculty of Science, Charles University, Albertov 6, 128 43 Praha 2, Czech Republic
| | | | - Jiří Kopáček
- Biology Centre of the Czech Academy of Sciences, Institute of Hydrobiology, 370 05 České Budějovice, Czech Republic
| | - Jan Rohovec
- Institute of Geology of the Czech Academy of Sciences, Rozvojová 269, 165 00 Prague 6, Czech Republic
| | - Jiří Kaňa
- Biology Centre of the Czech Academy of Sciences, Institute of Hydrobiology, 370 05 České Budějovice, Czech Republic
| | - Pavel Cudlín
- Global Change Research Centre of the Czech Academy of Sciences, Poříčí 3b, 60 300 Brno, Czech Republic
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Sebestyen SD, Ross DS, Shanley JB, Elliott EM, Kendall C, Campbell JL, Dail DB, Fernandez IJ, Goodale CL, Lawrence GB, Lovett GM, McHale PJ, Mitchell MJ, Nelson SJ, Shattuck MD, Wickman TR, Barnes RT, Bostic JT, Buda AR, Burns DA, Eshleman KN, Finlay JC, Nelson DM, Ohte N, Pardo LH, Rose LA, Sabo RD, Schiff SL, Spoelstra J, Williard KWJ. Unprocessed Atmospheric Nitrate in Waters of the Northern Forest Region in the U.S. and Canada. Environ Sci Technol 2019; 53:3620-3633. [PMID: 30830765 DOI: 10.1021/acs.est.9b01276] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Little is known about the regional extent and variability of nitrate from atmospheric deposition that is transported to streams without biological processing in forests. We measured water chemistry and isotopic tracers (δ18O and δ15N) of nitrate sources across the Northern Forest Region of the U.S. and Canada and reanalyzed data from other studies to determine when, where, and how unprocessed atmospheric nitrate was transported in catchments. These inputs were more widespread and numerous than commonly recognized, but with high spatial and temporal variability. Only 6 of 32 streams had high fractions (>20%) of unprocessed atmospheric nitrate during baseflow. Seventeen had high fractions during stormflow or snowmelt, which corresponded to large fractions in near-surface soil waters or groundwaters, but not deep groundwater. The remaining 10 streams occasionally had some (<20%) unprocessed atmospheric nitrate during stormflow or baseflow. Large, sporadic events may continue to be cryptic due to atmospheric deposition variation among storms and a near complete lack of monitoring for these events. A general lack of observance may bias perceptions of occurrence; sustained monitoring of chronic nitrogen pollution effects on forests with nitrate source apportionments may offer insights needed to advance the science as well as assess regulatory and management schemes.
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Affiliation(s)
- Stephen D Sebestyen
- USDA Forest Service , Northern Research Station , 1831 Highway 169 E , Grand Rapids , Minnesota 55744-3399 , United States
| | - Donald S Ross
- University of Vermont , Dept. of Plant and Soil Science , Burlington , Vermont 05405-1737 , United States
| | - James B Shanley
- U.S. Geological Survey (USGS) , New England Water Science Center , Montpelier , Vermont 05602 , United States
| | - Emily M Elliott
- University of Pittsburgh , Dept. of Geology and Environmental Science , Pittsburgh , Pennsylvania 15260-3332 , United States
| | - Carol Kendall
- USGS , Menlo Park , California 94025 , United States
| | - John L Campbell
- USDA Forest Service , Northern Research Station , Durham , New Hampshire 03824 , United States
| | - D Bryan Dail
- University of Maine , Department of Plant, Soil, and Environmental Science , Orono , Maine 04469 , United States
| | - Ivan J Fernandez
- University of Maine , School of Forest Resources , Orono , Maine 04469 , United States
| | - Christine L Goodale
- Cornell University , Ecology and Evolutionary Biology , Ithaca , New York 14850 , United States
| | | | - Gary M Lovett
- Cary Institute of Ecosystem Studies , Millbrook , New York 12545 , United States
| | - Patrick J McHale
- State University of New York College of Environmental Science and Forestry , Department of Environmental and Forest Biology , Syracuse , New York 13210 , United States
| | - Myron J Mitchell
- State University of New York College of Environmental Science and Forestry , Department of Environmental and Forest Biology , Syracuse , New York 13210 , United States
| | - Sarah J Nelson
- University of Maine , School of Forest Resources , Orono , Maine 04469 , United States
| | - Michelle D Shattuck
- University of New Hampshire , Dept. of Natural Resources and the Environment , Durham , New Hampshire 03824 , United States
| | - Trent R Wickman
- USDA Forest Service , National Forest System - Eastern Region , Duluth , Minnesota 55808 , United States
| | - Rebecca T Barnes
- Colorado College , Environmental Program , Colorado Springs , Colorado 80903 , United States
| | - Joel T Bostic
- University of Maryland Center for Environmental Science , Appalachian Laboratory , Frostburg , Maryland 21532 , United States
| | - Anthony R Buda
- USDA Agricultural Research Service , Pasture Systems and Watershed Management Research Unit , University Park , Pennsylvania 16802-3702 , United States
| | - Douglas A Burns
- USGS , NY Water Science Center , Troy , New York 12180 , United States
| | - Keith N Eshleman
- University of Maryland Center for Environmental Science , Appalachian Laboratory , Frostburg , Maryland 21532 , United States
| | - Jacques C Finlay
- University of Minnesota , Ecology, Evolution, and Behavior , St. Paul , Minnesota 55108 , United States
| | - David M Nelson
- University of Maryland Center for Environmental Science , Appalachian Laboratory , Frostburg , Maryland 21532 , United States
| | - Nobuhito Ohte
- Kyoto University , Department of Social Informatics , Kyoto , Kyoto Prefecture 6068501 , Japan
| | - Linda H Pardo
- USDA Forest Service , Northern Research Station , Burlington , Vermont 05405 , United States
| | - Lucy A Rose
- University of Minnesota , Department of Forest Resources , St. Paul , Minnesota 55108 , United States
| | - Robert D Sabo
- USDA Forest Service , Northern Research Station , Burlington , Vermont 05405 , United States
| | - Sherry L Schiff
- University of Waterloo , Department of Earth and Environmental Sciences , Waterloo , Ontario N2L 3G1 , Canada
| | - John Spoelstra
- Environment and Climate Change Canada , Canada Center for Inland Waters , Burlington , Ontario L7S 1A1 , Canada
| | - Karl W J Williard
- Southern Illinois University , Forestry Center for Ecology , Carbondale , Illinois 62901 , United States
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Navrátil T, Nováková T, Shanley JB, Rohovec J, Matoušková Š, Vaňková M, Norton SA. Larch Tree Rings as a Tool for Reconstructing 20th Century Central European Atmospheric Mercury Trends. Environ Sci Technol 2018; 52:11060-11068. [PMID: 30192133 DOI: 10.1021/acs.est.8b02117] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We propose the tree rings of European Larch ( Larix decidua) as a widely available and reliable geochemical archive of local and regional changes in atmospheric mercury (Hg). Mean Hg concentrations in larch tree rings from 8 background sites across the Czech Republic ranged from 2.2 to 4.8 μg kg-1; the maximum concentrations occurred in the period 1951-1970. At 3 sites impacted by Hg-emission sources [gold amalgamation processing, caustic soda production, and lead (Pb) ore smelting] mean larch tree ring Hg concentrations were significantly elevated relative to background sites. Changes in larch tree ring Hg concentrations were temporally coherent with known activities at the sites that would alter Hg emissions; the nearly simultaneous response in tree rings indicated little or no translocation of Hg within the larch bole. Based on the present-day atmospheric Hg concentration of 1.63 ng m-3 at the intensively monitored Czech Global Mercury Observation System site and the most recent mean tree ring Hg concentration of 2.8 μg kg-1 in co-located larch trees, we developed a simple distribution model of Hg between the atmosphere and larch tree rings. We applied the model using observed changes of Hg in larch tree rings from the countrywide background sites to reconstruct past atmospheric Hg concentrations in central Europe. Modeled Hg concentrations were in agreement with annual means from the European Monitoring and Evaluation Programme observatories.
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Affiliation(s)
- Tomáš Navrátil
- Institute of Geology of the Czech Academy of Science , Rozvojova 269 , 165 00 Prague , Czech Republic
| | - Tereza Nováková
- Institute of Geology of the Czech Academy of Science , Rozvojova 269 , 165 00 Prague , Czech Republic
| | - James B Shanley
- United States Geological Survey , PO Box 628, Montpelier , Vermont 05601 , United States
| | - Jan Rohovec
- Institute of Geology of the Czech Academy of Science , Rozvojova 269 , 165 00 Prague , Czech Republic
| | - Šárka Matoušková
- Institute of Geology of the Czech Academy of Science , Rozvojova 269 , 165 00 Prague , Czech Republic
| | - Maria Vaňková
- Institute of Geology of the Czech Academy of Science , Rozvojova 269 , 165 00 Prague , Czech Republic
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8
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Navrátil T, Šimeček M, Shanley JB, Rohovec J, Hojdová M, Houška J. The history of mercury pollution near the Spolana chlor-alkali plant (Neratovice, Czech Republic) as recorded by Scots pine tree rings and other bioindicators. Sci Total Environ 2017; 586:1182-1192. [PMID: 28237461 DOI: 10.1016/j.scitotenv.2017.02.112] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Revised: 02/13/2017] [Accepted: 02/13/2017] [Indexed: 05/21/2023]
Abstract
We assessed >100years of mercury (Hg) pollution recorded in the tree rings of Scots Pine near a Czech chlor-alkali plant operating since 1941. Hg concentrations in tree rings increased with the launching of plant operations and decreased when Hg emissions decreased in 1975 due to an upgrade in production technology. Similar to traditional bioindicators of pollution such as pine needles, bark and forest floor humus, Hg concentrations in Scots Pine boles decreased with distance from the plant. Mean Hg in pine bole in the 1940s ranged from 32.5μg/kg Hg at a distance of 0.5km from the plant to 5.4μg/kg at a distance of >4.7km, where tree ring Hg was the same as at a reference site, and other bioindicators also suggest that the effect of the plant was no longer discernible. Tree ring Hg concentrations decreased by 8-29μg/kg since the 1940s at all study sites including the reference site. The lack of exact correspondence between changes at the plant and tree ring Hg indicated some smearing of the signal due to lateral translocation of Hg from sapwood to heartwood. Bole Hg concentrations reflected local and regional atmospheric Hg concentrations, and not Hg wet deposition.
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Affiliation(s)
- Tomáš Navrátil
- Institute of Geology of CAS, v.v.i., Rozvojová 269, 165 00 Prague 6, Czech Republic.
| | - Martin Šimeček
- Institute of Geology of CAS, v.v.i., Rozvojová 269, 165 00 Prague 6, Czech Republic
| | | | - Jan Rohovec
- Institute of Geology of CAS, v.v.i., Rozvojová 269, 165 00 Prague 6, Czech Republic
| | - Maria Hojdová
- Institute of Geology of CAS, v.v.i., Rozvojová 269, 165 00 Prague 6, Czech Republic
| | - Jakub Houška
- Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences, Kamýcká 129, 165 21 Prague 6, Czech Republic
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Pourmokhtarian A, Driscoll CT, Campbell JL, Hayhoe K, Stoner AMK, Adams MB, Burns D, Fernandez I, Mitchell MJ, Shanley JB. Modeled ecohydrological responses to climate change at seven small watersheds in the northeastern United States. Glob Chang Biol 2017; 23:840-856. [PMID: 27472269 DOI: 10.1111/gcb.13444] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 06/13/2016] [Indexed: 06/06/2023]
Abstract
A cross-site analysis was conducted on seven diverse, forested watersheds in the northeastern United States to evaluate hydrological responses (evapotranspiration, soil moisture, seasonal and annual streamflow, and water stress) to projections of future climate. We used output from four atmosphere-ocean general circulation models (AOGCMs; CCSM4, HadGEM2-CC, MIROC5, and MRI-CGCM3) included in Phase 5 of the Coupled Model Intercomparison Project, coupled with two Representative Concentration Pathways (RCP 8.5 and 4.5). The coarse resolution AOGCMs outputs were statistically downscaled using an asynchronous regional regression model to provide finer resolution future climate projections as inputs to the deterministic dynamic ecosystem model PnET-BGC. Simulation results indicated that projected warmer temperatures and longer growing seasons in the northeastern United States are anticipated to increase evapotranspiration across all sites, although invoking CO2 effects on vegetation (growth enhancement and increases in water use efficiency (WUE)) diminish this response. The model showed enhanced evapotranspiration resulted in drier growing season conditions across all sites and all scenarios in the future. Spruce-fir conifer forests have a lower optimum temperature for photosynthesis, making them more susceptible to temperature stress than more tolerant hardwood species, potentially giving hardwoods a competitive advantage in the future. However, some hardwood forests are projected to experience seasonal water stress, despite anticipated increases in precipitation, due to the higher temperatures, earlier loss of snow packs, longer growing seasons, and associated water deficits. Considering future CO2 effects on WUE in the model alleviated water stress across all sites. Modeled streamflow responses were highly variable, with some sites showing significant increases in annual water yield, while others showed decreases. This variability in streamflow responses poses a challenge to water resource management in the northeastern United States. Our analyses suggest that dominant vegetation type and soil type are important attributes in determining future hydrological responses to climate change.
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Affiliation(s)
- Afshin Pourmokhtarian
- Department of Civil and Environmental Engineering, Syracuse University, Syracuse, NY, 13244, USA
| | - Charles T Driscoll
- Department of Civil and Environmental Engineering, Syracuse University, Syracuse, NY, 13244, USA
| | - John L Campbell
- US Forest Service, Northern Research Station, Durham, NH, 03824, USA
| | - Katharine Hayhoe
- Climate Science Center, Texas Tech University, Lubbock, TX, 79409, USA
| | - Anne M K Stoner
- Climate Science Center, Texas Tech University, Lubbock, TX, 79409, USA
| | - Mary Beth Adams
- Forest Service, Northern Research Station, Morgantown, WV, 26505, USA
| | | | - Ivan Fernandez
- School of Forest Resources and Climate Change Institute, University of Maine, Orono, ME, 04469-5722, USA
| | - Myron J Mitchell
- Department of Environmental Resources Engineering, SUNY-ESF, Syracuse, NY, 13210, USA
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Shanley JB, Engle MA, Scholl M, Krabbenhoft DP, Brunette R, Olson ML, Conroy ME. High Mercury Wet Deposition at a "Clean Air" Site in Puerto Rico. Environ Sci Technol 2015; 49:12474-12482. [PMID: 26368125 DOI: 10.1021/acs.est.5b02430] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Atmospheric mercury deposition measurements are rare in tropical latitudes. Here we report on seven years (April 2005 to April 2012, with gaps) of wet Hg deposition measurements at a tropical wet forest in the Luquillo Mountains, northeastern Puerto Rico, U.S. Despite receiving unpolluted air off the Atlantic Ocean from northeasterly trade winds, during two complete years the site averaged 27.9 μg m(-2) yr(-1) wet Hg deposition, or about 30% more than Florida and the Gulf Coast, the highest deposition areas within the U.S. These high Hg deposition rates are driven in part by high rainfall, which averaged 2855 mm yr(-1). The volume-weighted mean Hg concentration was 9.8 ng L(-1), and was highest during summer and lowest during the winter dry season. Rainout of Hg (decreasing concentration with increasing rainfall depth) was minimal. The high Hg deposition was not supported by gaseous oxidized mercury (GOM) at ground level, which remained near global background concentrations (<10 pg m(-3)). Rather, a strong positive correlation between Hg concentrations and the maximum height of rain detected within clouds (echo tops) suggests that droplets in high convective cloud tops scavenge GOM from above the mixing layer. The high wet Hg deposition at this "clean air" site suggests that other tropical areas may be hotspots for Hg deposition as well.
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Affiliation(s)
- James B Shanley
- U.S. Geological Survey, P.O. Box 628, Montpelier, Vermont 05601, United States
| | - Mark A Engle
- U.S. Geological Survey, El Paso, Texas 79968, United States
| | - Martha Scholl
- U.S. Geological Survey, Reston, Virginia 20192, United States
| | | | - Robert Brunette
- Eurofins Frontier Global Sciences Inc., Bothell, Washington 98011, United States
| | - Mark L Olson
- University of Illinois , Champaign, Illinois 61820, United States
| | - Mary E Conroy
- University of Vermont , Burlington, Vermont 05405, United States
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Campbell JL, Rustad LE, Porter JH, Taylor JR, Dereszynski EW, Shanley JB, Gries C, Henshaw DL, Martin ME, Sheldon WM, Boose ER. Quantity is Nothing without Quality: Automated QA/QC for Streaming Environmental Sensor Data. Bioscience 2013. [DOI: 10.1525/bio.2013.63.7.10] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Shanley JB, Moore R, Smith RA, Miller EK, Simcox A, Kamman N, Nacci D, Robinson K, Johnston JM, Hughes MM, Johnston C, Evers D, Williams K, Graham J, King S. MERGANSER: an empirical model to predict fish and loon mercury in New England lakes. Environ Sci Technol 2012; 46:4641-4648. [PMID: 22372609 DOI: 10.1021/es300581p] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
MERGANSER (MERcury Geo-spatial AssessmeNtS for the New England Region) is an empirical least-squares multiple regression model using mercury (Hg) deposition and readily obtainable lake and watershed features to predict fish (fillet) and common loon (blood) Hg in New England lakes. We modeled lakes larger than 8 ha (4404 lakes), using 3470 fish (12 species) and 253 loon Hg concentrations from 420 lakes. MERGANSER predictor variables included Hg deposition, watershed alkalinity, percent wetlands, percent forest canopy, percent agriculture, drainage area, population density, mean annual air temperature, and watershed slope. The model returns fish or loon Hg for user-entered species and fish length. MERGANSER explained 63% of the variance in fish and loon Hg concentrations. MERGANSER predicted that 32-cm smallmouth bass had a median Hg concentration of 0.53 μg g(-1) (root-mean-square error 0.27 μg g(-1)) and exceeded EPA's recommended fish Hg criterion of 0.3 μg g(-1) in 90% of New England lakes. Common loon had a median Hg concentration of 1.07 μg g(-1) and was in the moderate or higher risk category of >1 μg g(-1) Hg in 58% of New England lakes. MERGANSER can be applied to target fish advisories to specific unmonitored lakes, and for scenario evaluation, such as the effect of changes in Hg deposition, land use, or warmer climate on fish and loon mercury.
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Affiliation(s)
- James B Shanley
- US Geological Survey, P.O. Box 628, Montpelier, Vermont 05601, United States.
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Shanley JB, Chalmers AT. Streamwater fluxes of total mercury and methylmercury into and out of Lake Champlain. Environ Pollut 2012; 161:311-320. [PMID: 21835521 DOI: 10.1016/j.envpol.2011.07.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2011] [Accepted: 07/18/2011] [Indexed: 05/31/2023]
Abstract
From 2000 to 2004, we sampled for total mercury (THg) and methylmercury (MeHg) in inlet streams to Lake Champlain, targeting high flow periods to capture increases in THg and MeHg concentrations with increasing flow. We used these data to model stream THg and MeHg fluxes for Water Years 2001 through 2009. In this mountainous forested basin with a high watershed-to-lake area ratio of 18, fluvial export from the terrestrial watershed was the dominant source of Hg to the lake. Unfiltered THg and MeHg fluxes were dominated by the particulate fraction; about 40% of stream THg was in the filtered (<0.4 μm) phase. THg flux from the watershed to the lake averaged 2.37 μg m(-2) yr(-1), or about 13% of atmospheric Hg wet and dry deposition to the basin. THg export from the lake represented only about 3% of atmospheric Hg input to the basin.
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Affiliation(s)
- James B Shanley
- U.S. Geological Survey, P.O. Box 628, Montpelier, VT 05601, USA.
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Ross DS, Shanley JB, Campbell JL, Lawrence GB, Bailey SW, Likens GE, Wemple BC, Fredriksen G, Jamison AE. Spatial patterns of soil nitrification and nitrate export from forested headwaters in the northeastern United States. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2011jg001740] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Engle MA, Tate MT, Krabbenhoft DP, Schauer JJ, Kolker A, Shanley JB, Bothner MH. Comparison of atmospheric mercury speciation and deposition at nine sites across central and eastern North America. ACTA ACUST UNITED AC 2010. [DOI: 10.1029/2010jd014064] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Dittman JA, Shanley JB, Driscoll CT, Aiken GR, Chalmers AT, Towse JE. Ultraviolet absorbance as a proxy for total dissolved mercury in streams. Environ Pollut 2009; 157:1953-6. [PMID: 19250728 DOI: 10.1016/j.envpol.2009.01.031] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2008] [Revised: 01/29/2009] [Accepted: 01/30/2009] [Indexed: 05/22/2023]
Abstract
Stream water samples were collected over a range of hydrologic and seasonal conditions at three forested watersheds in the northeastern USA. Samples were analyzed for dissolved total mercury (THg(d)), DOC concentration and DOC composition, and UV(254) absorbance across the three sites over different seasons and flow conditions. Pooling data from all sites, we found a strong positive correlation of THg(d) to DOC (r(2)=0.87), but progressively stronger correlations of THg(d) with the hydrophobic acid fraction (HPOA) of DOC (r(2)=0.91) and with UV(254) absorbance (r(2)=0.92). The strength of the UV(254) absorbance-THg(d) relationship suggests that optical properties associated with dissolved organic matter may be excellent proxies for THg(d) concentration in these streams. Ease of sample collection and analysis, the potential application of in-situ optical sensors, and the possibility for intensive monitoring over the hydrograph make this an effective, inexpensive approach to estimate THg(d) flux in drainage waters.
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Affiliation(s)
- Jason A Dittman
- Syracuse University, Department of Civil and Environmental Engineering, 151 Link Hall, Syracuse, NY 13244, USA.
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Krám P, Oulehle F, Štědrá V, Hruška J, Shanley JB, Minocha R, Traister E. Geoecology of a Forest Watershed Underlain by Serpentine in Central Europe. Northeast Nat (Steuben) 2009. [DOI: 10.1656/045.016.0523] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Sebestyen SD, Boyer EW, Shanley JB. Responses of stream nitrate and DOC loadings to hydrological forcing and climate change in an upland forest of the northeastern United States. ACTA ACUST UNITED AC 2009. [DOI: 10.1029/2008jg000778] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Stephen D. Sebestyen
- Northern Research Station, Forest Service; U.S. Department of Agriculture; Grand Rapids Minnesota USA
| | - Elizabeth W. Boyer
- School of Forest Resources; Pennsylvania State University; University Park Pennsylvania USA
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Shanley JB, Mayer B, Mitchell MJ, Bailey SW. Seasonal and event variations in delta34S values of stream sulfate in a Vermont forested catchment: implications for sulfur sources and cycling. Sci Total Environ 2008; 404:262-268. [PMID: 18456308 DOI: 10.1016/j.scitotenv.2008.03.020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Stable sulfur (S) isotope ratios can be used to identify the sources of sulfate contributing to streamwater. We collected weekly and high-flow stream samples for S isotopic analysis of sulfate through the entire water year 2003 plus the snowmelt period of 2004. The study area was the 41-ha forested W-9 catchment at Sleepers River Research Watershed, Vermont, a site known to produce sulfate from weathering of sulfide minerals in the bedrock. The delta(34)S values of streamwater sulfate followed an annual sinusoidal pattern ranging from about 6.5 per thousand in early spring to about 10 per thousand in early fall. During high-flow events, delta(34)S values typically decreased by 1 to 3 per thousand from the prevailing seasonal value. The isotopic evidence suggests that stream sulfate concentrations are controlled by: (1) an overall dominance of bedrock-derived sulfate (delta(34)S approximately 6-14 per thousand); (2) contributions of pedogenic sulfate (delta(34)S approximately 5-6 per thousand) during snowmelt and storms with progressively diminishing contributions during base flow recession; and (3) minor effects of dissimilatory bacterial sulfate reduction and subsequent reoxidation of sulfides. Bedrock should not be overlooked as a source of S in catchment sulfate budgets.
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Shanley JB, Alisa Mast M, Campbell DH, Aiken GR, Krabbenhoft DP, Hunt RJ, Walker JF, Schuster PF, Chalmers A, Aulenbach BT, Peters NE, Marvin-DiPasquale M, Clow DW, Shafer MM. Comparison of total mercury and methylmercury cycling at five sites using the small watershed approach. Environ Pollut 2008; 154:143-54. [PMID: 18407389 DOI: 10.1016/j.envpol.2007.12.031] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2007] [Accepted: 12/13/2007] [Indexed: 05/20/2023]
Abstract
The small watershed approach is well-suited but underutilized in mercury research. We applied the small watershed approach to investigate total mercury (THg) and methylmercury (MeHg) dynamics in streamwater at the five diverse forested headwater catchments of the US Geological Survey Water, Energy, and Biogeochemical Budgets (WEBB) program. At all sites, baseflow THg was generally less than 1ng L(-1) and MeHg was less than 0.2ng L(-1). THg and MeHg concentrations increased with streamflow, so export was primarily episodic. At three sites, THg and MeHg concentration and export were dominated by the particulate fraction in association with POC at high flows, with maximum THg (MeHg) concentrations of 94 (2.56)ng L(-1) at Sleepers River, Vermont; 112 (0.75)ng L(-1) at Rio Icacos, Puerto Rico; and 55 (0.80)ng L(-1) at Panola Mt., Georgia. Filtered (<0.7microm) THg increased more modestly with flow in association with the hydrophobic acid fraction (HPOA) of DOC, with maximum filtered THg concentrations near 5ng L(-1) at both Sleepers and Icacos. At Andrews Creek, Colorado, THg export was also episodic but was dominated by filtered THg, as POC concentrations were low. MeHg typically tracked THg so that each site had a fairly constant MeHg/THg ratio, which ranged from near zero at Andrews to 15% at the low-relief, groundwater-dominated Allequash Creek, Wisconsin. Allequash was the only site with filtered MeHg consistently above detection, and the filtered fraction dominated both THg and MeHg. Relative to inputs in wet deposition, watershed retention of THg (minus any subsequent volatilization) was 96.6% at Allequash, 60% at Sleepers, and 83% at Andrews. Icacos had a net export of THg, possibly due to historic gold mining or frequent disturbance from landslides. Quantification and interpretation of Hg dynamics was facilitated by the small watershed approach with emphasis on event sampling.
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Affiliation(s)
- James B Shanley
- US Geological Survey, PO Box 628, Montpelier, VT 05601, USA.
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Park BB, Yanai RD, Fahey TJ, Bailey SW, Siccama TG, Shanley JB, Cleavitt NL. Fine Root Dynamics and Forest Production Across a Calcium Gradient in Northern Hardwood and Conifer Ecosystems. Ecosystems 2008. [DOI: 10.1007/s10021-008-9126-3] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Murdoch PS, Shanley JB. Flow-specific trends in river-water quality resulting from the effects of the Clean Air Act in three mesoscale, forested river basins in the northeastern United States through 2002. Environ Monit Assess 2006; 120:1-25. [PMID: 16897528 DOI: 10.1007/s10661-005-9028-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2004] [Accepted: 08/23/2005] [Indexed: 05/11/2023]
Abstract
Two new methods for assessing temporal trends in stream-solute concentrations at specific streamflow ranges were applied to long (40 to 50-year) but sparse (bi-weekly to quarterly sampling) stream-water quality data collected at three forested mesoscale basins along an atmospheric deposition gradient in the northeastern United States (one in north-central Pennsylvania, one in southeastern New York, and one in eastern Maine). The three data sets span the period since the implementation of the Clean Air Act in 1970 and its subsequent amendments. Declining sulfate (O4(2-)) trends since the mid 1960s were identified for all 3 rivers by one or more of the 4 methods of trend detection used. Flow-specific trends were assessed by segmenting the data sets into 3-year and 6-year blocks, then determining concentration-discharge relationships for each block. Declining sulfate (O4(2-)) trends at median flow were similar to trends determined using a Seasonal Kendall Tau test and Sen slope estimator. The trend of declining O4(2-) concentrations differed at high, median and low flow since the mid 1980s at YWC and NR, and at high and low flow at WR, but the trends leveled or reversed at high flow from 1999 through 2002. Trends for the period of record at high flows were similar to medium- and low-flow trends for Ca2++ Mg2+ concentrations at WR, non-significant at YWC, and were more negative at low flow than at high flow at NR; trends in nitrate (NO3-), and alkalinity (ALK) concentrations were different at different flow conditions, and in ways that are consistent with the hydrology and deposition history at each watershed. Quarterly sampling is adequate for assessing average-flow trends in the chemical parameters assessed over long time periods (approximately decades). However, with even a modest effort at sampling a range of flow conditions within each year, trends at specified flows for constituents with strong concentration-discharge relationships can be evaluated and may allow early detection of ecosystem response to climate change and pollution management strategies.
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Peters NE, Shanley JB, Aulenbach BT, Webb RM, Campbell DH, Hunt R, Larsen MC, Stallard RF, Troester J, Walker JF. Water and solute mass balance of five small, relatively undisturbed watersheds in the U.S. Sci Total Environ 2006; 358:221-42. [PMID: 15978657 DOI: 10.1016/j.scitotenv.2005.04.044] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2004] [Accepted: 03/25/2005] [Indexed: 05/03/2023]
Abstract
Geochemical mass balances were computed for water years 1992-1997 (October 1991 through September 1997) for the five watersheds of the U.S. Geological Survey Water, Energy, and Biogeochemical Budgets (WEBB) Program to determine the primary regional controls on yields of the major dissolved inorganic solutes. The sites, which vary markedly with respect to climate, geology, physiography, and ecology, are: Allequash Creek, Wisconsin (low-relief, humid continental forest); Andrews Creek, Colorado (cold alpine, taiga/tundra, and subalpine boreal forest); Río Icacos, Puerto Rico (lower montane, wet tropical forest); Panola Mountain, Georgia (humid subtropical piedmont forest); and Sleepers River, Vermont (humid northern hardwood forest). Streamwater output fluxes were determined by constructing empirical multivariate concentration models including discharge and seasonal components. Input fluxes were computed from weekly wet-only or bulk precipitation sampling. Despite uncertainties in input fluxes arising from poorly defined elevation gradients, lack of dry-deposition and occult-deposition measurements, and uncertain sea-salt contributions, the following was concluded: (1) for solutes derived primarily from rock weathering (Ca, Mg, Na, K, and H(4)SiO(4)), net fluxes (outputs in streamflow minus inputs in deposition) varied by two orders of magnitude, which is attributed to a large gradient in rock weathering rates controlled by climate and geologic parent material; (2) the net flux of atmospherically derived solutes (NH(4), NO(3), SO(4), and Cl) was similar among sites, with SO(4) being the most variable and NH(4) and NO(3) generally retained (except for NO(3) at Andrews); and (3) relations among monthly solute fluxes and differences among solute concentration model parameters yielded additional insights into comparative biogeochemical processes at the sites.
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Affiliation(s)
- N E Peters
- U.S. Geological Survey, 3039 Amwiler Rd., Suite 130 Atlanta, GA 30360-2824, USA.
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Gao N, Armatas NG, Shanley JB, Kamman NC, Miller EK, Keeler GJ, Scherbatskoy T, Holsen TM, Young T, McIlroy L, Drake S, Olsen B, Cady C. Mass balance assessment for mercury in Lake Champlain. Environ Sci Technol 2006; 40:82-9. [PMID: 16433336 DOI: 10.1021/es050513b] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
A mass balance model for mercury in Lake Champlain was developed in an effort to understand the sources, inventories, concentrations, and effects of mercury (Hg) contamination in the lake ecosystem. To construct the mass balance model, air, water, and sediment were sampled as a part of this project and other research/monitoring projects in the Lake Champlain Basin. This project produced a STELLA-based computer model and quantitative apportionments of the principal input and output pathways of Hg for each of 13 segments in the lake. The model Hg concentrations in the lake were consistent with measured concentrations. Specifically, the modeling identified surface water inflows as the largest direct contributor of Hg into the lake. Direct wet deposition to the lake was the second largest source of Hg followed by direct dry deposition. Volatilization and sedimentation losses were identified as the two major removal mechanisms. This study significantly improves previous estimates of the relative importance of Hg input pathways and of wet and dry deposition fluxes of Hg into Lake Champlain. It also provides new estimates of volatilization fluxes across different lake segments and sedimentation loss in the lake.
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Affiliation(s)
- Ning Gao
- Department of Chemistry, St. Lawrence University, Canton, New York 13617, USA.
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Majer V, Krám P, Shanley JB. Rapid regional recovery from sulfate and nitrate pollution in streams of the western Czech Republic--comparison to other recovering areas. Environ Pollut 2005; 135:17-28. [PMID: 15701389 DOI: 10.1016/j.envpol.2004.10.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2004] [Accepted: 10/19/2004] [Indexed: 05/24/2023]
Abstract
Hydrochemical changes between 1991 and 2001 were assessed based on two synoptic stream surveys from the 820-km2 region of the Slavkov Forest and surrounding area, western Czech Republic. Marked declines of sulfate, nitrate, chloride, calcium and magnesium in surface waters were compared with other areas of Europe and North America recovering from acidification. Declines of sulfate concentration in the Slavkov Forest (-30 microeq L(-1) yr(-1)) were more dramatic than declines reported from other sites. However, these dramatic declines of strong acid anions did not generate a widespread increase of stream water pH in the Slavkov Forest. Only the most acidic streams experienced a slight increase of pH by 0.5 unit. An unexpected decline of stream water pH occurred in slightly alkaline streams.
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Affiliation(s)
- Vladimír Majer
- Czech Geological Survey, Klárov 3, 118 21 Prague 1, Czech Republic
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Kamman NC, Chalmers A, Clair TA, Major A, Moore RB, Norton SA, Shanley JB. Factors influencing mercury in freshwater surface sediments of northeastern North America. Ecotoxicology 2005; 14:101-11. [PMID: 15931961 DOI: 10.1007/s10646-004-6262-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
We report on an inventory and analysis of sediment mercury (Hg) concentrations from 579 sites across northeastern North America. Sediment Hg concentrations ranged from the limit of detection ca. 0.01-3.7 microg g(-1) (dry weight, d.w.), and the average concentration was 0.19 microg g(-1) (d.w.) Sediment methylmercury concentrations ranged from 0.15 to 21 ng g(-1) (d.w.) and the mean concentration was 3.83 ng g(-1) (d.w.). Total Hg concentrations (HgT) were greatest in lakes > reservoirs > rivers, although the proportion of Hg as methylmercury showed an inverse pattern. Total Hg was weakly and positively correlated with the sediment organic matter and percent of watershed as forested land, and weakly and negatively correlated with sediment solids content, drainage area, and agricultural land. Sediment methylmercury concentrations were weakly and positively correlated to wetland area, and weakly and negatively correlated to drainage area. Methylmercury, expressed as a percentage of HgT was positively correlated to agricultural land area. For sites with co-located sediment and fish-tissue sampling results, there was no relationship between sediment Hg and fish-tissue Hg. Finally, our data indicate that at least 44% of waters across the region have sediment HgT concentrations in excess of Canadian and United States minimum sediment contaminant guidelines for the protection of aquatic biota.
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Affiliation(s)
- Neil C Kamman
- Vermont Department of Environmental Conservation, 103 South Main St, Waterbury, VT 05671, USA.
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Shanley JB, Kamman NC, Clair TA, Chalmers A. Physical controls on total and methylmercury concentrations in streams and lakes of the northeastern USA. Ecotoxicology 2005; 14:125-34. [PMID: 15931963 DOI: 10.1007/s10646-004-6264-z] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
The physical factors controlling total mercury (HgT) and methylmercury (MeHg) concentrations in lakes and streams of northeastern USA were assessed in a regional data set containing 693 HgT and 385 corresponding MeHg concentrations in surface waters. Multiple regression models using watershed characteristics and climatic variables explained 38% or less of the variance in HgT and MeHg. Land cover percentages and soil permeability generally provided modest predictive power. Percent wetlands alone explained 19% of the variance in MeHg in streams at low-flow, and it was the only significant (p < 0.02) predictor for MeHg in lakes, albeit explaining only 7% of the variance. When stream discharge was added as a variable it became the dominant predictor for HgT in streams, improving the model r2 from 0.19 to 0.38. Stream discharge improved the MeHg model more modestly, from r2 of 0.25 to 0.33. Methylation efficiency (MeHg/HgT) was modeled well (r2 of 0.78) when a seasonal term was incorporated (sine wave with annual period). Physical models explained 18% of the variance in fish Hg concentrations in 134 lakes and 55% in 20 reservoirs. Our results highlight the important role of seasonality and short-term hydrologic changes to the delivery of Hg to water bodies.
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Affiliation(s)
- James B Shanley
- U.S. Geological Survey, P.O. Box 628, Montpelier, VT 05602, USA.
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Shanley JB, Krám P, Hruška J, Bullen TD. A Biogeochemical Comparison of Two Well-Buffered Catchments with Contrasting Histories of Acid Deposition. ACTA ACUST UNITED AC 2004. [DOI: 10.1023/b:wafo.0000028363.48348.a4] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Abstract
At Fever Brook, a 1260-ha forested basin in central Massachusetts, highway deicing salt application increased the solute flux in streamflow by 120% above background flux (equivalent basis) during a 2-yr period. Attempts to isolate the nonsalt component of stream solute fluxes have commonly subtracted salt contributions based on the net Cl flux (Cl output in streamflow minus Cl input in precipitation). In these studies, any net Na flux in excess of the amount needed to balance the net Cl flux has been attributed to weathering. At Fever Brook, however, the net output of Na was less than the net output of Cl, suggesting a loss of Na within the basin. The Na sink was inferred to be cation exchange of Na for Ca and Mg in the soil. A method was developed to quantify the exchange based on a Na budget, which included an independent estimate of the Na flux from weathering. The amount of exchange was apportioned to Ca and Mg based on their relative concentrations in the stream. The background fluxes of Ca and Mg (i.e., those that would occur in the absence of deicing salts) were calculated by subtracting the amounts from ion exchange plus the much smaller direct contributions in deicing salts from the observed fluxes. Ion exchange and direct salt contributions increased the net output fluxes of Ca and Mg, each by 44% above background. In basins that receive deicing salts, failure to account for cation exchange thus may result in an underestimate of the flux of Na from weathering and overestimates of the fluxes of Ca and Mg from weathering.
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