Nitrate contamination in the Illinois River that flows into the Gulf of Mexico has dropped in recent years, according to new research by the University of Illinois and published in the Journal of Environmental Quality.
Over the 2010 to 2014 period, the river's nitrate concentrations fell 10 percent, the study reports. As of 2015, nitrate concentrations in the river were down 15 percent.
A key driver behind the reduction in nitrates, which come from sources including farm fertilizer and treated wastewater, stems from newer forms of corn crops that leave less nitrogen fertilizer being in the ground.
"The varieties (of corn) that are planted these days and in the last few years are more robust in a lot of different ways," Greg McIsaac, an agriculture engineering professor who co-authored the study, told the AP.
Nitrates in the Illinois River can end up in the Gulf of Mexico's "dead zone" by way of the Mississippi River. The Gulf of Mexico's dead zone is an area devoid of oxygen caused by nutrient runoff from agricultural and other sources. The dead zone is harmful to aquatic life. The federal government has a target to cut nutrient pollution that makes it way into the dead zone by 45 percent.