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

We deployed hydroponic eelgrass, Zostera marina L., to test its use as a se ntinel accumulator and indicator of the source of water-borne lead (Pb) con tamination in the marine environment. Eelgrass 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 fro m seepage sites near the Jamaica Island landfill (JIL). Deployed eelgrass, water samples from seepage sites, and sediment from the deployment sites we re analyzed for Pb concentration and stable Pb isotopic composition. Isotop ic composition was used to distinguish recent anthropogenic Pb inputs from background Pb in the estuary. Isotope ratios indicated that two groundwater seeps were a source of recent anthropogenic Pb (i.e. industrial Pb from th e landfill) to Jamaica Cove. The eelgrass that showed the strongest presenc e of industrial Pb (having the lowest Pb-206/Pb-207) was closest to a high volume seep that drained from the JIL and had a similar isotope signature a s 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. (C) 1999 Elsevier S cience Ltd. All rights reserved.