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Full-Text Articles in Environmental Sciences
Noble Gases Identify The Mechanisms Of Fugitive Gas Contamination In Drinking-Water Wells Overlying The Marcellus And Barnett Shales, Thomas H. Darrah, Avner Vengosh, Robert B. Jackson, Nathaniel R. R. Warner, Robert J. Poreda
Noble Gases Identify The Mechanisms Of Fugitive Gas Contamination In Drinking-Water Wells Overlying The Marcellus And Barnett Shales, Thomas H. Darrah, Avner Vengosh, Robert B. Jackson, Nathaniel R. R. Warner, Robert J. Poreda
Dartmouth Scholarship
Horizontal drilling and hydraulic fracturing have enhanced energy production but raised concerns about drinking-water contamination and other environmental impacts. Identifying the sources and mechanisms of contamination can help improve the environmental and economic sustainability of shale-gas extraction. We analyzed 113 and 20 samples from drinking-water wells overlying the Marcellus and Barnett Shales, respectively, examining hydrocarbon abundance and isotopic compositions (e.g., C2H6/CH4, δ13C-CH4) and providing, to our knowledge, the first comprehensive analyses of noble gases and their isotopes (e.g., 4He, 20Ne, 36Ar) in groundwater near shale-gas wells. We addressed two questions. (i) Are elevated levels of hydrocarbon gases in …
Do Low-Mercury Terrestrial Resources Subsidize Low-Mercury Growth Of Stream Fish? Differences Between Species Along A Productivity Gradient, Darren M. Ward, Keith H. Nislow, Carol L. Folt
Do Low-Mercury Terrestrial Resources Subsidize Low-Mercury Growth Of Stream Fish? Differences Between Species Along A Productivity Gradient, Darren M. Ward, Keith H. Nislow, Carol L. Folt
Dartmouth Scholarship
Low productivity in aquatic ecosystems is associated with reduced individual growth of fish and increased concentrations of methylmercury (MeHg) in fish and their prey. However, many stream-dwelling fish species can use terrestrially-derived food resources, potentially subsidizing growth at low-productivity sites, and, because terrestrial resources have lower MeHg concentrations than aquatic resources, preventing an increase in diet-borne MeHg accumulation. We used a large-scale field study to evaluate relationships among terrestrial subsidy use, growth, and MeHg concentrations in two stream-dwelling fish species across an in-stream productivity gradient. We sampled young-of-the-year brook trout ( Salvelinus fontinalis ) and Atlantic salmon ( Salmo salar …
Algal Blooms Reduce The Uptake Of Toxic Methylmercury In Freshwater Food Webs, Paul C. Pickhardt, Carol L. Folt, Celia Y. Chen, Bjoern Klaue, Joel D. Blum
Algal Blooms Reduce The Uptake Of Toxic Methylmercury In Freshwater Food Webs, Paul C. Pickhardt, Carol L. Folt, Celia Y. Chen, Bjoern Klaue, Joel D. Blum
Dartmouth Scholarship
Mercury accumulation in fish is a global public health concern, because fish are the primary source of toxic methylmercury to humans. Fish from all lakes do not pose the same level of risk to consumers. One of the most intriguing patterns is that potentially dangerous mercury concentrations can be found in fish from clear, oligotrophic lakes whereas fish from greener, eutrophic lakes often carry less mercury. In this study, we experimentally tested the hypothesis that increasing algal biomass reduces mercury accumulation at higher trophic levels through the dilution of mercury in consumed algal cells. Under bloom dilution, as algal biomass …