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John Myers, Forum Communications, Published August 26 2012

Study looks at effects of sulfate on wild rice

DULUTH, Minn. – In canning jars, cattle troughs and 100 lakes across Minnesota, scientists are working at breakneck speed to unravel the relationship between the state’s iconic wild rice plant and sulfate.

Sulfate is a natural chemical commonly found in air, soil and water. It can be found in discharges from facilities such as mining operations, wastewater treatment plants and other industrial facilities, according to the Minnesota Pollution Control Agency.

As wild rice enthusiasts in canoes harvest this year’s crop across the Northland, researchers are looking to see how much sulfate is too much for wild rice.

The results will help determine whether the state should relax its longstanding limit on sulfate for lakes and rivers where rice grows.

The sulfate limit may help plot the future of the state’s mining industry – both for planned expansions of taconite mining and processing and development of one of the world’s largest deposits of copper and nickel.

Some taconite mining operations, wastewater treatment plants and proposed copper mining operations might not be able to meet the current sulfate limit of 10 parts per million in wild rice waters, experts say.

“Yeah, it’s not a very big deal, is it?’’ joked John Pastor, University of Minnesota Duluth researcher who is heading the laboratory research of the sulfate study.

Wild rice is the state’s most important wild food crop. Throw in Indian culture – manomin, or wild rice, is a sacred staple for Ojibwe people – add politicians, environmentalists and the Minnesota Chamber of Commerce all watching, and there’s real drama in the outcome.

And, by the way, everyone wants the results a little more than a year from now.

The $1.5 million study – Minnesota’s largest involving wild rice – started slowly last year, expanded this summer and will conclude after the 2013 growing season, when state funding is scheduled to run out. All of the research is getting input from a 32-person “advisory committee’’ representing taconite companies, business groups, environmentalists, Indian resource agencies and research universities.

“There’s a lot of interest, for sure, but I wouldn’t call it pressure,’’ said Mark Tomasek, the PCA’s supervisor of water quality standards, who will help decide the new sulfate standard based on the research. “With that interest comes the money to do the research, so that’s the benefit of how this all happened.”

Pastor is looking at wild rice plants in his lab, grown in individual Ball canning jars subjected to varying degrees of sulfate and other tightly controlled substances.

Pastor also has wild rice growing in plastic cattle tubs outside at the UMD’s experimental farm. There, he’s able to re-create actual ecosystems and tweak the water chemistry to simulate elevated sulfate levels.

Researchers at the farm will soon be testing wild rice reaction in water with less than 10 parts per million of sulfate, but also with 50, 100, 150 and 300 parts per million, to see what happens.

“We have 105 little lakes here where we can reproduce all sorts of impacts on the rice,’’ Pastor said.

Meanwhile, University of Minnesota-Twin Cities limno-geologist Amy Myrbo has crews surveying actual lakes and streams across the state, conducting an intensive study of the water and sediment on lakes with wild rice and lakes that might or could have rice at some point.

Pastor already knows a little bit about sulfate and wild rice. He’s been studying wild rice in cattle watering tubs at UMD’s field station on Jean Duluth Road for eight years under a more than $1 million project funded by the National Science Foundation.

That research dealt with Pastor’s career-long expertise on the effects of nutrients on plants. Pastor found that the single biggest factor determining successful wild rice crops is the plant’s ability to get adequate nitrogen. When sulfate is high, it appears that plants don’t get enough nitrogen, he said.

Experts say it’s nearly certain that sulfate itself is not the issue. It takes a complicated interaction of microbes, or bacteria, to transform sulfate in the water into sulfides in the sediment, namely hydrogen sulfide, which becomes the culprit. In an oxygen-starved environment, the bacteria “breathe” sulfate, and they “exhale” hydrogen sulfide.

“If sulfate is having this negative effect on wild rice, it’s probably because it can be turned into hydrogen sulfide, which can be very toxic to plants,’’ said Ed Swain, PCA research scientist who is coordinating the mercury sulfate project.


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John Myers writes for the Duluth News Tribune