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New Bedford Harbor Long Term Monitoring Program
Citation:
Bergen, B. New Bedford Harbor Long Term Monitoring Program. New Bedford Harbor Public Meeting, New Bedford, MA, November 05, 2015.
Impact/Purpose:
Inform the public about on going monitoring at the New Bedford Harbor Superfund site.
Description:
New Bedford Harbor (NBH), located in southeastern Massachusetts, was designated as a Superfund site in 1983 due to unacceptably high levels of sediment contamination by polychlorinated biphenyls (PCBs). Based on human health and environmental concerns, the decision was made to dredge the PCB-contaminated sediments from the harbor. EPA Region I (Boston, MA) and the U.S. Army Corps of Engineers (New England Division) required a monitoring program to assess the effects and effectiveness of remedial activities at this marine Superfund site. The Atlantic Ecology Division (AED), of the U.S. EPA’s National Health and Environmental Effects Research Laboratory (NHEERL), had extensive experience in near-coastal monitoring and designed the long-term monitoring program for this site. The goal of the New Bedford Harbor Long-Term Monitoring Program (NBH-LTM) is to measure spatial and temporal chemical and biological changes in sediment, water and biota to assess the effects and effectiveness of the remedial activities. A systematic, probabilistic sampling design was used to select sampling stations. This unbiased design allowed the three areas of the harbor to be compared spatially and temporally to quantify changes resulting from remedial activities. Sediment is collected at each station and chemical (e.g., PCBs, metals), physical (e.g., grain size), and biological (e.g., toxicity, benthic community) measurements conducted on all samples. To date, samples have been collected six times: 1) 1993 - baseline collection, 2) 1995 - following the Hot Spot sediment removal from the upper harbor, 3) 1999 - before dredging pilot studies, 4) 2004 - prior to full scale upper harbor remediation, 5) 2009 - after several years of full-scale remediation, and 6) 2014 – before final cleanup dredging began. Also, PCB accumulation in deployed mussels was measured twice each year. This presentation describes the overall long-term monitoring plan and results from the first six rounds of sample collections. Briefly, there is a decreasing spatial PCB gradient from the northern portion of the site (upper harbor, the primary source of PCBs) to the southern boundary (outer harbor, Buzzards Bay). Concurrently, there is an increasing diversity and abundance in the benthic community from north to south. The contaminant and biological gradients have been maintained since the 1993 baseline collection; however, since the onset of full scale remediation, PCB concentrations have decreased and one of the benthic indices has shown significant improvement in the southern areas of the site.