Use of Mercury Stable Isotope Analysis for Sediment Source Identification
Northgate will be presenting a poster at the Battelle conference on a forensic application of stable isotope speciation to identify sources of mercury (Hg) that have contaminated sediment in a San Francisco Bay harbor. We collected sediment samples over a 200-acre drainage basin that discharges storm water runoff to the harbor, including undeveloped hillside slopes and the commercial/industrial corridor adjacent to the harbor. We compared these upland samples to benthic sediments from within the harbor and from a reference station in San Francisco Bay. Joel D. Blum, PhD, professor in the Earth and Environmental Sciences Department at the University of Michigan, Ann Arbor, analyzed the Hg stable isotope composition of the samples. The stable isotope analyses indicated that the Hg in harbor sediments was derived from the regional contamination in San Francisco Bay. The Hg associated with urban runoff (i.e., erosion from hillside slopes and runoff from the developed commercial/industrial corridor) had a distinctive Hg isotope signature that was unrelated to San Francisco Bay sediment. Northgate’s findings demonstrated that urban runoff contributes a negligible amount of Hg to the harbor sediment.
Wednesday, January 14, at 5:45 – 7:00 p.m., Poster Group 2, Session D9 Contaminant Forensics