HR: 0800h
AN: B11B-0392    [Abstracts]
TI: Mercury Biogeochemistry in Wetlands of the Western Adirondack Region, New York, USA
AU: * Demers, J D
EM: jdd24@cornell.edu
AF: Cornell University, Department of Natural Resources, Ithaca, NY 14853, United States
AU: Yavitt, J B
EM: jby1@cornell.edu
AF: Cornell University, Department of Natural Resources, Ithaca, NY 14853, United States
AU: Driscoll, C T
EM: ctdrisco@syr.edu
AF: Syracuse University, Civil and Environmental Engineering, Syracuse, NY 13244,
AB: Wetlands are important controls of inorganic mercury and methyl mercury flux to surface waters. Research suggests that greater area of wetlands within a watershed is often correlated with greater amounts of dissolved mercury and methyl mercury in associated surface waters and fish; however, the importance of wetland type is seldom considered. This study quantifies differences in mercury biogeochemistry in individual wetlands of varying hydrologic setting in the western Adirondack region of New York, USA. Herein, we compare the pool size, flux, and residence time of mercury and methyl mercury in headwater wetlands perched at the top of their watersheds, with riparian wetlands lower in the landscape. The pool size of mercury was greater in the top 50 cm of peat in riparian wetlands as compared with headwater wetlands, and the molar ratio of Hg:C shows that 2-4x more Hg per unit C was retained in these riparian wetlands. Mercury concentrations in peat porewater were consistently greater in headwater wetlands than in riparian wetlands during the non-growing season when water table levels were high. MeHg concentrations peaked at the end of the growing season, when water table levels were low. Riparian wetlands were spatial and temporal hotspots of dissolved mercury and methyl mercury production, whereas headwater wetlands were less dynamic. Riparian wetlands provided the greatest flux of mercury and methyl mercury from wetlands to surface waters when compared to other wetlands within the same watershed. The residence time of mercury in riparian wetlands was ~200 years, whereas the residence time of mercury in headwater wetlands exceeded 500 years. Differences in the flux of mercury from wetlands was primarily determined by the hydrology of the different wetland types, rather than by the concentration of mercury in porewaters. Based on the residence time, the magnitude of the flux of mercury from wetlands should not rapidly change with changes in atmospheric deposition of mercury.
DE: 0483 Riparian systems (0744, 1856)
DE: 0489 Trace element cycling (4875)
DE: 0497 Wetlands (1890)
DE: 1806 Chemistry of fresh water
DE: 1813 Eco-hydrology
SC: Biogeosciences [B]
MN: 2007 Fall Meeting