title: Isotopic evidence for determining the sources of dissolved organic sulfur in a forested catchment.
abstract: Understanding sulfur (S) biogeochemistry, especially in those watersheds subject to elevated levels of atmospheric S inputs, is needed for determining the factors that contribute to acidification, nutrient losses and the mobilization of toxic solutes (e.g., monomeric aluminum and methylmercury). S is found in a variety of both organic and inorganic forms undergoing a range of biotic and abiotic transformations. In watersheds with decreasing atmospheric S inputs, internal cycling is becoming dominant in affecting whether there is net loss or retention of S. Little attention has been given to the role of dissolved organic S (DOS) in affecting S biogeochemistry. DOS originates from assimilatory and bacterial dissimilatory S reduction (BDSR), the latter of which produces (34)S-depleted S. Within groundwater of the Archer Creek Catchment in the Adirondack Mountains (New York) there was reoxidation of reduced S, which was an important source of SO4(2-). DOS in surface waters had a higher variation of δ(34)S-DOS values (-6.0 to +8.4‰) than inorganic S with δ(34)S-SO4(2-) values ranging from +1.0 to +5.8‰. Inverse correlations between δ(34)S values of SO4(2-) and DOS suggested that BDSR played an important role in producing DOS.
authors.affiliation: Department of Environmental and Forest Biology, State University of New York-College of Environmental Science and Forestry (SUNY-ESF) , Syracuse, New York 13210, United States.
authors.forename: Phil-Goo
authors.initials: PG
authors.lastname: Kang
authors.forename: Myron J
authors.initials: MJ
authors.lastname: Mitchell
authors.forename: Bernhard
authors.initials: B
authors.lastname: Mayer
authors.forename: John L
authors.initials: JL
authors.lastname: Campbell
mesh_terms: D060587:Groundwater / Q000032:analysis / Q000737:chemistry; D009518:New York; D013431:Sulfates / Q000032:analysis; D013455:Sulfur / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D013431:Sulfates; D014874:Water Pollutants, Chemical; D013455:Sulfur