Citation:

MUCHA, Amy P., J. BING-CANAR, C. Roth, M. MILLS, L. P. BURKHARD, DAVE MOUNT, J. M. LAZORCHAK, AND K. Bustavson. Assessment Of Bioaccumulation Potential Following Dredging In Mainistique, Michigan. Presented at The Sixth International Conference on Remediation of Contaminated Sediments, New Orleans, LA, February 07 - 10, 2011.

Impact/Purpose:

To discuss how to assess bioaccumulation in a post-remedial environment, where a new baseline has emerged. Also sediment, fish SPMD and bioaccumulation testing data will be presented.

Description:

After the Superfund remedy of the Mainistique River and Harbor that occurred in 1996 to 2001, PCB concentrations in sediment have gone down substantially. Prior to dredging, the average PCB concentration was 28 ppm (all depth intervals) and the current average in sediments is 0.72 ppm (2008 surficial data). Detailed statistical analyses of PCB concentration trends have been done by Region 5's FIELDS Group (Fully Integrated Environmental Decision System), and have shown that in the harbor there is a statistically significant downward trend of PCBs in surficial sediments. However, in teh slightly upstream western slips, there is no statistically significant trend. In addition, fish data from the State of Michigan has found that comparing between 2004 and 2008 data, there are different patterns in concentration changes over time. Bottom-feeding fish show a decrease in PCB concentrations over time, however the red horse suckers do not show a similar decline in 2008 vs. 2004 datasets. SPMD analyses were also performed here in 2005 and 2008, and while the results are not entirely consistent, they do indicate different bioaccumulation potential in the sediments, depending on spatial location. The site is part of an Area of Concern, and is currently a Great Lakes Legacy Act site with sampling occurring in the summer of 2010. How to assess bioacccumulation in a post-remedial environment, where a new baseline has emerged will be discussed, and will include presentation of sediment, fish, SPMD and bioaccumulation testing data. Our Ideas of "stories to tell": • large PCB mass removal • large decrease in PCB sediment levels, but not mirrored in fish tissue • difficult population (fish) sampling issues: open system; resident vs. non-resident fish distinctions; highly variable fish PCB levels; fish species and age class issues. • significant flow dynamics change from planned navigation dredging planned this fall leading to a new baseline Questions for you: • do you have any pre-remediation fish PCB levels? FOR FURTHER INFORMATION, CONTACT ROGER B. YEARDLEY, JR., LAND REMEDIATION AND POLLUTION CONTROL DIVISION, 513-569-7548.

Record Details: