title: Has submarine groundwater discharge been overlooked as a source of mercury to coastal waters?
abstract: We measured the mercury (Hg) in groundwater, aquifer sediments, and surface water in Waquoit Bay (Massachusetts) and found that this toxic metal (range: <3.2-262 pM) was being released within the subterranean estuary, with similarly high levels (range: 18-256 pM) found in the surface waters of the bay. None of the dissolved species (DOC, chloride, and Fe) normally observed to influence Hg partitioning correlated well with the observed Hg concentrations. It was hypothesized that this was in part due to the variable loading in time and space of Hg onto the aquifer sands in combination with the seasonality of groundwater flow through the aquifer. Aquifer sediment samples from the study site ranged from <1 to 12.5 pmol of Hg/g of sediment, suggesting log Kd values on the order of 1. We hypothesize that this was due to the low organic carbon content typical of the aquifer sediments. Last, itwas estimated that submarine groundwater discharge supplied 0.47-1.9 nmol of Hg m(-2) day(-1) to the bay, which is an order of magnitude higher than the atmospheric deposition rate for the northeastern U.S.
authors.affiliation: Woods Hole Oceanographic Institution, Department of Marine Chemistry and Geochemistry, Woods Hole, Massachusetts 02543, USA. sbone@nature.berkeley.edu
authors.forename: Sharon E
authors.initials: SE
authors.lastname: Bone
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Charette
authors.forename: Carl H
authors.initials: CH
authors.lastname: Lamborg
authors.forename: Meagan Eagle
authors.initials: ME
authors.lastname: Gonneea
mesh_terms: D004784:Environmental Monitoring; D005618:Fresh Water / Q000032:analysis; D019015:Geologic Sediments / Q000032:analysis; D008404:Massachusetts; D008628:Mercury / Q000032:analysis*; D012623:Seawater / Q000032:analysis; D014872:Water Movements; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014881:Water Supply / Q000032:analysis
chemical_list: D014874:Water Pollutants, Chemical; D008628:Mercury