title: Peat Bogs as Hotspots for Organoarsenical Formation and Persistence.
abstract: Peatlands have received significant atmospheric inputs of As and S since the onset of the Industrial Revolution, but the effect of S deposition on the fate of As is largely unknown. It may encompass the formation of As sulfides and organosulfur-bound As, or the indirect stimulation of As biotransformation processes, which are presently not considered as important As immobilization pathways in wetlands. To investigate the immobilization mechanisms of anthropogenically derived As in peatlands subjected to long-term atmospheric pollution, we explored the solid-phase speciation of As, Fe, and S in English peat bogs by X-ray absorption spectroscopy. Additionally, we analyzed the speciation of As in pore- and streamwaters. Linear combination fits of extended X-ray absorption fine structure (EXAFS) data imply that 62-100% (average: 82%) of solid-phase As (Astot: 9-92 mg/kg) was present as organic As(V) and As(III). In agreement with appreciable concentrations of organoarsenicals in surface waters (pH: 4.0-4.4, Eh: 165-190 mV, average Astot: 1.5-129 μg/L), our findings reveal extensive biotransformation of atmospheric As and the enrichment of organoarsenicals in the peat, suggesting that the importance of organometal(loid)s in wetlands subjected to prolonged air pollution is higher than previously assumed.
authors.affiliation: Section for Environmental Chemistry and Physics, Department of Plant and Environmental Sciences, University of Copenhagen , DK-1871 Frederiksberg C, Denmark.|Soil Chemistry Group, Institute of Biogeochemistry and Pollutant Dynamics, Department of Environmental Systems Science, CHN, ETH Zurich , 8092 Zurich, Switzerland.
authors.forename: Christian
authors.initials: C
authors.lastname: Mikutta
authors.affiliation: Upland Environments Research Unit, Geography, School of Environment, Education and Development, The University of Manchester , Manchester M13 9PL, U.K.
authors.forename: James J
authors.initials: JJ
authors.lastname: Rothwell
mesh_terms: D000393:Air Pollutants; D001151:Arsenic / Q000032:analysis*; D001152:Arsenicals / Q000737:chemistry*; D004739:England; D007501:Iron / Q000032:analysis; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis*; D013440:Sulfides / Q000737:chemistry; D013455:Sulfur / Q000032:analysis; D053833:Wetlands; D056928:X-Ray Absorption Spectroscopy
chemical_list: D000393:Air Pollutants; D001152:Arsenicals; D012987:Soil; D012989:Soil Pollutants; D013440:Sulfides; C045816:arsenic trisulfide; D013455:Sulfur; D007501:Iron; D001151:Arsenic