Biogeochemical and geomorphological controls on mercury dynamics in a macrotidal salt marsh, Bay of Fundy, Canada.

摘要

Salt marsh biogeochemistry is generally dominated by sulfur transformations, and sulfate-reducing bacteria have been implicated as primary methylators of mercury (Hg). Some salt marshes have been shown to support high methylmercury (MeHg) production rates that may have adverse effects on biota, however little is known about the Hg dynamics of macrotidal salt marshes that dominate the important Bay of Fundy ecoregion in Canada. This study's aim is to provide a preliminary assessment of the distribution of, and controls on, sediment and pore water MeHg concentrations in a salt marsh heavily influenced by macrotidal activity in New Brunswick, Canada. Concentrations of bulk and dissolved total mercury (THg), MeHg, sulfate, sulfide, iron and chloride were determined along a geomorphic gradient and along the estuarine salinity gradient. THg and MeHg concentrations were frequently less than those found in the adjacent estuary, except in localized areas, suggesting a potentially important role for salt marshes.