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The New Bedford Harbor Superfund Site Long Term Monitoring Program: Results from 1993 to 2014
Citation:
Bergen, B. The New Bedford Harbor Superfund Site Long Term Monitoring Program: Results from 1993 to 2014. Remediation and Management of Contaminated Sediments. 9th International Conference, New Orleans, LA, January 09 - 12, 2017.
Impact/Purpose:
The purpose of this product is to transmit the results of a sediment long term monitoring program from the New Bedford Harbor Superfund site to a national meeting of sediment site managers and stakeholders.
Description:
Background. New Bedford Harbor (NBH), located in southeastern Massachusetts, was designated as a marine Superfund site in 1983 due to sediment contamination by polychlorinated biphenyls (PCBs). Based on risks to human health and the environment, the first two phases of the site cleanup involved dredging PCB-contaminated sediments from the harbor. Therefore, a long-term monitoring program (LTM) was developed to measure spatial and temporal chemical and biological changes in sediment, water, and biota to assess the effects and effectiveness of the remedial activities. Approach. A systematic, probabilistic sampling design was used to select approximately 70 sediment sampling stations. Sediment was collected at each station and chemical (e.g., PCBs, metals), physical (e.g., grain size), and biological (e.g., benthic community) measurements were conducted on all samples. There have been six sample collections to date: 1993-baseline, 1995-post hot spot removal, 1999-prior to full scale dredging, and then at 5 year intervals: 2004, 2009, and 2014. Mussel (Mytilus edulis) bioaccumulation has also been measured twice yearly. Results. There is a decreasing spatial gradient in sediment PCB concentrations from the northern boundary (upper harbor) to the southern boundary (outer harbor) of the site. Along this same transect, there is an increase in biological condition (e.g., benthic community diversity). Temporally, 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 throughout the site and one of the benthic community indices has shown significant improvement in the lower and outer harbor areas.