Determining Bioavailability of Metals in Lake Superior

A fortuitous calm prevailed on Lake Superior for a week in late April while UW-Madison’s James Hurley and other scientists collected air, water, sediment, and biota samples aboard the Environmental Protection Agency’s (EPA) research vessel Lake Guardian. The work was part of a UW Sea Grant project to determine the bioavailability of heavy metals in the lake-that is, how easily zinc, cadmium, copper, and other potentially toxic metals can be absorbed into the tissues of aquatic organisms.

The good weather was ideal for Hurley’s first attempt to adapt to ship-board conditions the ultra-clean sampling method he has used frequently on shore. Hurley developed the sensitive technique with Martin Shafer, in a project lead by David Armstrong, to measure minute quantities of metals in streams flowing into the lake. Hurley, Armstrong, and Shafer are water chemists at the UW-Madison.

The bioavailability of metals depends on their particular chemical form, or species, Hurley said. That form depends on how they interact with minerals and organic matter as they flow through a watershed on their way to the lake.

Hurley, Armstrong, and Shafer are creating a geographical information systems (GIS) framework to relate speciation and bioavailability information to watershed characteristics, such as surface and bedrock geology, land cover, and soil type. The results will provide a basis for assessing and predicting metal bioavailability in the Great Lakes basin.

The EPA generously donated ship time aboard the Guardian to the project.

Caption: Researchers aboard the Lake Guardian sample zooplankton at night using a specially designed net for detecting trace metals. photo by Doug Knauer, Wisconsin Dept. of Natural Resources

Last updated 17 August 2000 by Karl
All contents copyright 2000 University of Wisconsin Sea Grant Institute

http://www.seagrant.wisc.edu/Communications/news/LDstories/2000/Bioavailability.html