Will PCB's in Lake Michigan ever decline to acceptable levels?
Ann Arbor, MI — A sophisticated, state-of-the-art lake model predicts that Polychlorinated Biphenyl's (PCB's) will decline in Lake Michigan and eventually reach acceptable levels in lake water. PCB's are the ubiquitous chemicals that have negatively impacted the environment for decades.
Acceptable levels of PCB's for the protection of wildlife (0.074 parts per trillion) are predicted to be reached by 2018. Acceptable levels of PCB's for the protection of human health (0.026 parts per trillion) will not be reached until by 2045.
Xiaomi Zhang, who works at the U.S. EPA Large Lakes Research Station in Grosse Ile, MI says that "PCB production in this country ended in 1977. Since then, there has been much done in the Lake Michigan basin to remove PCBs from contaminated areas. But, we continue to be concerned about the chemical, such as in fish consumption advisories. Development of a rigorous mass balance model enabled us to make predictions of PCB concentrations in the lake. With these predictions, we can now estimate when various health-related criteria will be met."
"The lake levels of PCBs are declining and will continue to decline due to the production ban and remediation efforts. These efforts have reduced the amount of PCBs entering the lake. The lake system itself has mechanisms to conduct some "self-remediation" that is on-going."
These self-remediation mechanisms include PCB loss from water to air (volatilization), deep burial in sediments, and losses through the Straits of Mackinac to Lake Huron. Of these, loss from the water to air is the largest.
Original Publication Information
Results of this study, "The Lake Michigan contaminant transport and fate model, LM2-toxic: Development, overview, and application," are reported by Xiaomi Zhang, Kenneth R. Rygwelski and Ronald Rossmann in the latest issue (Volume 35, No. 1, pp. 128-136) of the Journal of Great Lakes Research, published by Elsevier, 2009.
Contacts
For more information about the study, contact Xiaomi Zhang, Z-Tech, Large Lakes Research Station, 9311 Groh Road, Grosse Ile, MI 48138, zhang.xiaomi@epa.gov, (734) 692-7624.
For information about the Journal of Great Lakes Research, contact Marlene Evans, Editor, National Water Research Institute, 11 Innovation Boulevard, Saskatoon, SK, S7N 3H5, Canada; editor@iaglr.org; (608) 692-1076.
Since 1967, IAGLR has served as the focal point for compiling and disseminating multidisciplinary knowledge on North America's Laurentian Great Lakes and other large lakes of the world and their watersheds. In part, IAGLR communicates this knowledge through publication of the Journal of Great Lakes Research, available to members in print and electronic form. A searchable archive of the journal is available online and includes the abstracts of articles from the journal's inception in 1975 through the most recent issue. In addition, complete articles are available to members who have signed up for an electronic subscription.