Breaking the Cycle

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A new NASA grant will support the Environmental Science Initiative’s work to help address the link between climate change and extreme nitrogen cycles

A team of ASRC researchers has been awarded a $2 million, three-year grant from NASA to investigate nitrogen flux runoff from the Mississippi River Basin into the Gulf of Mexico. Led by Charlie Vörösmarty, Director of the ASRC’s Environmental Science Initiative, the researchers will use models, geospatial data sets, and remote sensing to map nitrogen flux in real time and to explore scenarios of future management options.

Nitrogen is essential to life, moving between the land, water, air, and organisms in a never-ending process called the nitrogen cycle. But human activity has led to a staggering increase in nitrogen pollution resulting from agriculture, urbanization, and sewage, each causing global-scale degradation of inland and coastal waterways.

“Of all the things that humans have done on the planet, they have disrupted the nitrogen cycle more than anything else,” said Peter Groffman, a professor in the ASRC’s Environmental Science Initiative and a co-principal investigator on the study. “We pull nitrogen out of the air and make fertilizer to grow food, but we don’t use the fertilizer very efficiently, and we end up polluting our water and air with excessive nitrogen.” Extreme precipitation and drought due to climate change has only increased the flow of nitrogen into receiving waters, Groffman added.

The Gulf of Mexico is one region that has been heavily impacted by excessive nitrogen runoff, mainly from agricultural fields. During summer months, the runoff creates prime conditions for algae blooms, which decay and cause hypoxic (oxygen poor) conditions. This creates dead zones that impact many underwater species.

Climate change is expected to exacerbate nitrogen runoff issues in the Mississippi River Basin.

“The river basin is a critical region to conduct our studies,” said ASRC Environmental Science Initiative Professor Dianne Greenfield, another co-principal investigator on the study. “Multiple climate models predict the area will experience more intense storms such as hurricanes in the near future. The basin is also very rapidly losing its protective buffer of wetlands due to sea level rise. Our research should allow for some deep and rich analysis of nitrogen response to climate stressors.”

The team plans to create a framework that will link remote sensing satellites and other geospatial data to established models that can detect and analyze variations in nitrogen due to climate events. One advantage of the resulting framework will be the ability to create a nitrogen ‘weather map’ that provides a near-real time picture of changing nitrogen fluxes across the basin. The team hopes their framework will improve nitrogen surveillance, facilitate a better understanding of its role in climate events, and help inform policy and management decisions for urbanization and agriculture.

“Climate events, land use, nitrogen application rates, and regulations all vary quite a bit within the basin, creating this multi headed dragon of factors that all affect nitrogen across the basin, but to different degrees,” said Vörösmarty. “Having a systematic framework to analyze all this data will allow us to map out nitrogen dynamics with great temporal and spatial specificity and generate the best advice for management.”