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A river runs through it

Climate@Noon discusses greenhouse gas emissions

Martha Gerig of Michigan Sea Grant conducts a water sample in the Manistee River in the Lower Peninsula to test for greenhouse gas concentrations during her Ph.D. work at the University of Notre Dame. Gerig then compared those samples with the Tippecanoe River in northern Indiana. (Photo courtesy of Martha Gerig)

MARQUETTE — “Water is the most critical resource issue of our lifetime and our children’s lifetime. The health of our waters is the principal measure of how we live on the land.”

This quote from geomorphologist and hydrologist Luna Leopold perhaps sums up the message of a talk given by Martha Gerig, Ph.D., an extension educator for Michigan Sea Grant, at a Northern Climate Network Climate@Noon event Friday at Northern Michigan University.

Gerig discussed how climate change and humans impact water quality during her presentation, which was called: “The Connection Between Agriculture and Climate Change? A River Runs Through It.”

Gerig’s presentation focused on her measurements of greenhouse gas emissions on the Manistee River in the Lower Peninsula and the Tippecanoe River in northern Indiana. This work allowed her to examine the impacts of agriculture by comparing the rivers, as the Manistee River is 83% forested, while the Tippecanoe River is 82% agricultural.

“I wanted to create a study that really honed in on this concept of a larger basin with really getting a good snapshot of what we were doing. So the way I did this, was, I made a study designed to account for surrounding land use, our stream size versus our ungradable rivers and cease it,” Gerig said.

To compare the two rivers, Gerig and her 10-person research team selected 80 sites within each of the two watersheds and sampled each site seasonally to capture dynamics throughout the year.

This “seasonal snapshot” required a great deal of time and patience, Gerig noted, adding that the team would cover 300 square miles within a 24-hour period.

“We needed to make sure it was on a day when weather conditions were consistent and then we sampled both of these watersheds within a single season and repeated this,” Gerig said. “We collected (data on) stream depth, water velocity, just regular parameters and then our water chemistry sample, that nutrient nitrate and then the dissolved greenhouse gas nitrous oxide.”

Capturing nitrate in an air-tight bottle wasn’t the easiest process, especially in the middle of winter, Gerig continued.

It was vital to know the concentration of each sample, but the primary concern was what’s actually being emitted into the atmosphere, she said.

Gerig’s research concluded that nitrous oxide increases with nitrate nitrogen concentration, depending on land use and the season of the year.

This differs in the winter and summer, with a reduced concentration of nitrous oxide and nitrate nitrogen in the winter, she said.

Gerig explained the important process of denitrification — or the reduction of nitrate — slows down during the winter months.

Her study showed the reduced denitrification in the winter may be due to the decreased ability to transform that bioavailable molecular nitrogen.

Her research, combined with other data, indicates climate change will impact many fisheries and one of the main concerns is the mortality rate of lake whitefish.

With warmer temperatures, there will be less ice cover, therefore slowly eliminating the protection for those lake whitefish eggs that require ice cover to hatch in the spring.

This temperature shift has the potential to not only impact fish survival but it may lead to changes in lake stratification patterns. Water temperature is crucial in lake whitefish as it regulates metabolism and growth, Gerig noted.

Gerig hopes to continue educating the public on these impacts of climate change and come up with a solution to reverse the trends observed in rivers and the Great Lakes.

“My role with Michigan Sea Grant as an educator — and what I hope to sort of bring to the table — is this element of environmental change,” Gerig said. “So whether that’s in our landscape or what we have as human impacts … How do we arm our coastlines in a way that they are able to adapt to these rapidly changing environmental conditions as well as water safety? The high lake levels — how do we change how we as humans interact with the lake and shoreline?”

Jackie Jahfetson can be reached at 906-228-2500, ext. 248.

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