345 - Investigating Mercury in Soils of a Rural Salt Marsh in Massachusetts, USA: spatial and temporal patterns, speciation, source origins, and mobility

Salt marsh soils are biogeochemical hot spots and develop through a combination of inorganic sedimentation facilitated by tidal inundation and organic matter accumulation from productive vegetation. Here, we investigate what controls internal Hg cycling. We took cores (105 cm depth) in the Plum Island Sound salt marsh in Massachusetts, and analyzed them for total Hg (THg) and Methyl-Hg (MeHg), mobility, fallout radionuclide chronometers, and auxiliary measures. Results show total THg concentrations of 212±201 µg kg-1 (mean±SD; range of 6-860 µg kg-1), which strongly exceed nearby sediments (82 µg kg-1) and result in high pools sizes of Hg sequestered in these soils (83±73 mg m-2). MeHg concentrations average 1.2±2.4 µg kg-1 (0.1-14.3 µg kg-1), largely lack correlations with THg (p>0.05), and generally account for

Authors: Buyun Du, Ting Wang, Inke Forbrich, Jun Zhou, Joshua Landis, Prentiss Balcom, Elsie Sunderland, Daniel Obrist