Case Western Reserve University geologist Gerald Matisoff speculates the heavy winter snow melts contribute to the growing "dead zone" problem of low oxygen concentrations in Lake Erie's basin.
He reported on findings during the International Association of Great Lakes Research meeting at the University of Windsor in Ontario.
Matisoff provided an overview of 22 studies that will appear in an upcoming Journal of Great Lakes Research.
The 320 pages of research findings came from data collected on two research expeditions on Lake Erie in 2002 and 2003 and funded by the U.S. Environmental Protection Agency.
During the lake trips, Matisoff led a research team that took water and sediments samples to understand carbon and nutrient cycling, food dynamics and oxygen depletion in the basin.
The U.S.-Canadian and multi-institutional study sought answers to why the central basin has become a "dead zone."
According to Matisoff, the research yielded several other key findings:
Researchers for years believed that spring water flushed phosphorus into the lake, but Matisoff said the data revealed a new phenomenon that the year following some heavy winter melts raised phosphorous levels to those of the 1970s—before measures were taken to clean up the lake.
Matisoff said at this point it still is speculation that the problem results from human behavior such as spreading liquid manure on snow to no-till conservation efforts that keep fertilizers in the top soil and easily removed in quick melts or heavy rains and melts.
"We may have to rethink some of the environmental practices," he said.
Much of the phosphorus input is coming from the Detroit River from the flow from the upper lakes and as thought as from waste treatment plants that treat industrial wastes from the greater Detroit area. Another source of phosphorus is the Maumee River from farmland erosion and chemical leaching into the waterways.
While Matisoff speculates the winter runoff is the problem instead of the spring rains, he backs up his reasoning from other research.
In studies on Rock and Old Woman Creeks that feed water to Lake Erie, Matisoff found that particles from winter melts can "travel tens of kilometers from the field to the lake in one fell swoop."
"Once you get a good runoff event, all these particles wash right into the lake," he added.
In recent years, Matisoff has focused research on the waterways feeding into the lake.
"The watershed drives what is happening in the lake. Until we understand what takes place in the watershed, we will not be able understand what is happening in the lake," stated Matisoff.
Case Western Reserve University is committed to the free exchange of ideas, reasoned debate and intellectual dialogue. Speakers and scholars with a diversity of opinions and perspectives are invited to the campus to provide the community with important points of view, some of which may be deemed controversial. The views and opinions of those invited to speak on the campus do not necessarily reflect the views of the university administration or any other segment of the university community.