title: Spatial Dependence of Reduced Sulfur in Everglades Dissolved Organic Matter Controlled by Sulfate Enrichment.
abstract: Sulfate inputs to the Florida Everglades stimulate sulfidic conditions in freshwater wetland sediments that affect ecological and biogeochemical processes. An unexplored implication of sulfate enrichment is alteration of the content and speciation of sulfur in dissolved organic matter (DOM), which influences the reactivity of DOM with trace metals. Here, we describe the vertical and lateral spatial dependence of sulfur chemistry in the hydrophobic organic acid fraction of DOM from unimpacted and sulfate-impacted Everglades wetlands using X-ray absorption spectroscopy and ultrahigh-resolution mass spectrometry. Spatial variation in DOM sulfur content and speciation reflects the degree of sulfate enrichment and resulting sulfide concentrations in sediment pore waters. Sulfur is incorporated into DOM predominantly as highly reduced species in sulfidic pore waters. Sulfur-enriched DOM in sediment pore waters exchanges with overlying surface waters and the sulfur likely undergoes oxidative transformations in the water column. Across all wetland sites and depths, the total sulfur content of DOM correlated with the relative abundance of highly reduced sulfur functionality. The results identify sulfate input as a primary determinant on DOM sulfur chemistry to be considered in the context of wetland restoration and sulfur and trace metal cycling.
authors.affiliation: U.S. Geological Survey , Boulder, Colorado 80303, United States.|Department of Civil, Environmental, and Architectural Engineering, University of Colorado Boulder , Boulder, Colorado 80309, United States.
authors.forename: Brett A
authors.identifier: 0000-0002-5555-7733
authors.initials: BA
authors.lastname: Poulin
authors.affiliation: Department of Civil, Environmental, and Architectural Engineering, University of Colorado Boulder , Boulder, Colorado 80309, United States.
authors.forename: Joseph N
authors.initials: JN
authors.lastname: Ryan
authors.affiliation: Department of Earth and Environmental Sciences, University of Illinois at Chicago , Chicago, Illinois 60607, United States.
authors.forename: Kathryn L
authors.initials: KL
authors.lastname: Nagy
authors.affiliation: Skidaway Institute of Oceanography, Marine Sciences Department, University of Georgia , Savannah, Georgia 31401, United States.
authors.forename: Aron
authors.initials: A
authors.lastname: Stubbins
authors.affiliation: Research Group for Marine Geochemistry, Institute for Chemistry and Biology of the Marine Environment (ICBM), University of Oldenburg , Carl-von-Ossietzky-Strasse 9-11, D-26129 Oldenburg, Germany.
authors.forename: Thorsten
authors.initials: T
authors.lastname: Dittmar
authors.affiliation: U.S. Geological Survey , Reston, Virginia 20192, United States.
authors.forename: William
authors.initials: W
authors.lastname: Orem
authors.affiliation: U.S. Geological Survey , Middleton, Wisconsin 53562, United States.
authors.forename: David P
authors.initials: DP
authors.lastname: Krabbenhoft
authors.affiliation: U.S. Geological Survey , Boulder, Colorado 80303, United States.
authors.forename: George R
authors.initials: GR
authors.lastname: Aiken
mesh_terms: D005618:Fresh Water / Q000737:chemistry; D013431:Sulfates; D013455:Sulfur; D014874:Water Pollutants, Chemical; D053833:Wetlands
chemical_list: D013431:Sulfates; D014874:Water Pollutants, Chemical; D013455:Sulfur