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PR-B alumnus returns to present research to students, community

Pine River-Backus students and residents were reintroduced to an alumnus when he presented the results of scientific research he led with the University of Minnesota-Duluth.

Dr. Nathan Johnson, son of Owen Johnson and graduate of Pine River-Backus, Princeton and the University of Texas presented the results of research he lead through the University of Minnesota, Duluth on sulfates and the environment. Johnson presented to classes at PR-B as well as community members later on March 17. Photo by Travis Grimler
Dr. Nathan Johnson, son of Owen Johnson and graduate of Pine River-Backus, Princeton and the University of Texas presented the results of research he lead through the University of Minnesota, Duluth on sulfates and the environment. Johnson presented to classes at PR-B as well as community members later on March 17. Photo by Travis Grimler
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Pine River-Backus students and residents were reintroduced to an alumnus when he presented the results of scientific research he led with the University of Minnesota-Duluth.

Nathan Johnson, the son of Nancy and Owen (formerly of Pine River Dental Care) Johnson, returned to the school where he graduated to share his research on the impact of sulfates on the environment and absorption of mercury into fish. His research was completed at the University of Minnesota-Duluth, with his team of undergraduates and other researchers in related fields such as biology.

Johnson's research tracked nature's reaction to sulfate, in what Johnson called "sulfur cycles." Johnson's research revealed impacts of sulfur that is released into the ecosystem by natural systems like volcanic eruptions, as well as manmade air pollution and mining processes.

Johnson's team tracked the cycle of sulfate once it enters lakes and other water sources. His research found that these sulfates, which are considered benign, are consumed by natural bacteria found in lake and marsh mud and the bottoms of deep lakes (both places where oxygen is lacking) and converted to sulfide, which is unstable and toxic.

Part of Johnson's research was to determine the impact of sulfide on wild rice growth. They found that wild rice will not grow in an environment with even low doses of sulfide, so lakes near pollution sources are much less likely to grow wild rice than lakes farther from those sources.

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Johnson's group also found that sulfide is an important part in the bioaccumulation of mercury in fish. They found that with higher sulfide levels, fish can accumulate more mercury than they do without it.

Ultimately, Johnson's team found that higher sulfide levels negatively impact rice growth, and increase mercury in fish. Johnson's team also found that iron in these lakes can tie up sulfur to prevent the formation of sulfide, but that is a sort of race against the bacteria.

Johnson presented this research multiple times in the Pine River community, including to various class levels during the school day, and once to community members in the school media center March 17.

After Johnson graduated from PR-B, he received a bachelor's degree in environmental engineering from Princeton University as well as a master's degree and PhD from the University of Texas, Austin.

He now works at the University of Minnesota-Duluth, where he works with state and federal resource management agencies. His research on the sulfur cycle was in cooperation with various agencies, including the Minnesota Pollution Control Agency, the Department of Natural Resources, the Clean Water Lands and Legacy Act, the Army Corps of Engineers, the U.S. Geological Survey, and the Office of Undergraduate Research.

Related Topics: JOHNSON
Travis Grimler began work at the Echo Journal Jan. 2 of 2013 while the publication was still split in two as the Pine River Journal and Lake Country Echo. He is a full time reporter/photographer/videographer for the paper and operates primarily out of the northern stretch of the coverage area (Hackensack to Jenkins).
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