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Monitoring dredging effectiveness using biological and chemical markers of exposure
Citation:
LAZORCHAK, J. M., J. R. MEIER, K. M. FRITZ, P. A. WERNSING, M. MILLS, AND B. Patterson. Monitoring dredging effectiveness using biological and chemical markers of exposure. Presented at SETAC Europe, Seville, SPAIN, May 23 - 27, 2010.
Impact/Purpose:
When completed, findings from this research will be used by regulatory agencies, remedial project managers, and dredging practitioners to select the most effective and environmentally prudent remediation techniques and long term monitoring at contaminated sediment sites around the U.S.
Description:
Sediments in portions of the Ashtabula and Ottawa rivers are contaminated with polychlorinated biphenyls (PCBs) and polyaromatic hydrocarbons (PAHs) and both rivers have been designated by the International Joint Commission as a Great Lakes Area of Concern. Approximately 550,000 cubic yards of contaminated sediments were removed during a remedial dredging activity at Ashtabula River, while portions of the Ottawa River are expected to have approximately 257,000 cubic yards removed. The primary objective for this field investigation was to evaluate surrogate and biological indicators in the ecosystem to characterizxe contaminant exposure before, during and following dredging. This was done by measuring PCB and PAH accumulation in whole fish tissue and in benthic macroinvertebrates, assessing macroinvertebrate integrity, assessing changes in DNA damage in liver and blood, and scoring external and histopathological lesions (including tumors) in brown bullheads. Biomarker levels in indigenous fish were compared to those collected at a reference site, Conneaut Creek for the Ashtabula River site and an upstream site for the Ottawa River site. DNA damage was measured using the Comet assay in brown bullhead catfish (Ameiurus nebulosus) collected by electrofishing throughout the Ashtabula dredge project area. Benthic macroinvertebrates were collected using Hester-Dendy artificial substrates by deployment at three locations in the Ashtabula dredge project area as well as at an upstream reference site and 18 sites within a 5.5 mile project area for the Ottawa dredge project. The dredging activities have been completed and the post dredging characterization is currently underway for the Ashtabula River, while pre-dredging characterization has been completed for the Ottawa Project.