Isotope ratios of 206~Pb/207Pb in eelgrass, Zostera marina, indicate sources of Pb in an estuary

摘要

We deployed hydroponic eelgrass, Zostera marina L., to test its use as a sentinel accumulator and indicator of the source of water-borne lead (Pb) contamination in the marine environment. Eeigrass was deployed unrooted in the water column in the vicinity of the Portsmouth Naval Shipyard, located on Seavey Island in Portsmouth Harbor of New Hampshire and Maine, offshore ftom seepage sites near the Jamaica lsland landfill (JIL). Deployed eeigrass, water samples from seepage sites, and sediment from the deployment sites were analyzed for Pb concentration and stable Pb isotopic composition. Isotopic composition was used to distinguish recent anthropogenic Pb inputs from background Pb in the estuary. lsotope ratios indicated that two groundwater seeps were a source of recent anthropogenic Pb (i.e. industrial Pb from the landfill) to Jamaica Cove. The eelgrass that showed the strongest presence of industrial Pb (having the lowest 206~Pb/207~Pb) was closest to a high volume seep that drained from the JIL and had a similar isotope signature as well as elevated Pb concentrations. These data confirm a source of water-borne industrial Pb in the estuary and show that eelgrass can function as a sentinel accumulator of Pb from anthropogenic sources.