Release of historic DDT from sediment sources and uptake by aquatic organisms
Ann Arbor, MI —DDT, while having been banned in North America for over 2 decades, is still a concern for fish and wildlife, particularly in those areas in which it was historically applied.
Semi-permeable Membrane Devices (SPMDs), a new technology that mimics how fish absorb contaminants, were used to monitor DDT in the waters around the Holland Marsh, 40 km north or Toronto, Canada. The results show that there are concentrations of DDT released from sediments to water under certain conditions that could impact fish and wildlife.
"We know that DDT is still present in the sediments of agricultural areas where it has been historically applied," says David Lembcke a Scientist at the Lake Simcoe Region Conservation Authority. "We were looking for an inexpensive method to test if DDT is moving from the sediment to the water in the Holland Marsh. While we will need to conduct further sampling using fish, our results did uncover DDT levels that have the potential to impact fish and wildlife."
In the Holland Marsh, and other areas of intense agriculture, DDT was regularly, and widely, used to control pests from the 1940s to 1960s. Even after being banned in 1985, DDT remains present in soils and sediments. The chemical nature of DDT allows it to bind to soils and sediments where it is less likely to harm fish and other wildlife. However, high rainfall can saturate soils, weakening this bond, and allowing DDT to be released into water and become accumulated in the food chain. In our study, SPMDs were used in place of fish tissue sampling to monitor DDT concentrations and determine under what environmental conditions it is released. Our results found DDT moving from soils and sediments into to the waters of the Holland Marsh as well as moving downstream towards Lake Simcoe, particularly during rainy years. A comparison of these DDT concentrations to management guidelines found that DDT concentrations in the water have the potential to impact fish along with the bird and animal species that consume these fish.
Original Publication Information
Results of this study, "Use of Semipermeable Membrane Devices to investigate the impacts of DDT (Dichlorodiphenyltrichloroethane) in the Holland Marsh environs of the Lake Simcoe Watershed (Ontario, Canada),," are reported by David Lembcke et al. in the latest issue (Volume 37, Suppl. 3, pp. 142-147) of the Journal of Great Lakes Research, published by Elsevier, 2011.
Contacts
For more information about the study, contact contact David Lembcke, Lake Simcoe Region Conservation Authority, Newmarket, Ontario Canada, D.Lembcke@lsrca.on.ca, (905) 895-1281.
For information about the Journal of Great Lakes Research, contact Marlene Evans, Editor, National Water Research Institute, Environment Canada, 11 Innovation Boulevard, Saskatoon, SK, S7N 3H5, Canada; jglr@ec.gc.ca; (306) 975-5310.
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