Regeneration of wetlands near farms would greatly reduce water pollution

Flow of water from fertilizers and manures in agricultural regions has led to high levels of nitrate in groundwater, rivers and coastal areas. These high levels of nitrate can threaten the safety of drinking water and can cause problems with algal blooms and pollution of aquatic ecosystems.

Previous research has shown that wetlands improve water quality, but what is the impact of wetlands on nitrate removal now, and what improvements could wetland regeneration deliver in the future?

Researchers from the University of Illinois at Chicago and the University of Waterloo wanted to evaluate these details at the U.S. scale and publish their findings in a new paper that appeared in the journal Nature.

Their study examines the positive impacts of wetlands on water quality and the potential of using wetland regeneration as a key strategy for improving water quality, particularly in River Basin areas. Mississippi and the Gulf of Mexico.

In fact the wetland has a cleansing effect when water full of nitrate enters its confines. A chemical reaction occurs that removes the harmful nitrate from the water, allowing harmless nitrogen gas to be released into the atmosphere and cleaner water to flow downstream.

“Unfortunately, most of the original bogs in the U.S. were originally drained or destroyed to make way for agriculture or urban development. Ironically, there are areas with the greatest nitrate problems, as a result of agriculture and intensive use of nitrogen fertilizers, also as areas with the few remaining wetlands, “said Kimberly Van Meter, UIC assistant professor of earth and environmental sciences and co lead author of the paper.

The researchers used maps of wetlands left across the U.S. to measure the amount of nitrate currently being removed by wetlands. Despite the high levels of wet loss, their findings suggest that nitrate loads in the Mississippi River could be about 50% higher than they currently are without the presence of wetlands.

The huge contribution of wetlands to normal nitrate removal is important for two main reasons, according to Van Meter at UIC and her colleagues Frederick Cheng, Danyka Byrnes and Nandita Basu, all from the University of Waterloo.

“First, the Mississippi River is the largest source of nitrogen to the Gulf of Mexico and the main cause of the large dead zone that appears in the Gulf every summer. Second, it has conventional wetland defenses. eroded in recent years, particularly by revisions of the Trump-administered Clean Water Rule, which removed protections for about half of U.S. wetlands, “Van Meter said.

The researchers also simulated computer model simulations to better understand how wetland regeneration would benefit water quality.

“We found that by targeting the restoration of wetlands to areas in the U.S. with the highest levels of nitrate pollution, even a 10% increase in the normal wetland range could increase nitrate levels in rivers and streams. cut in half, “Van Meter said.

The cost of a wetland venture is estimated at $ 3.3 billion annually, an amount that researchers have described as feasible by current government spending rates. While that is twice the estimated cost of a noninvasive approach, the model showed that it would remove 40 times more nitrogen.

“You’ll get a lot more bang for your buck if wetland conservation and regeneration is focused,” said Nandita Basu, professor of civil and environmental engineering, and earth and environmental sciences at the University of Waterloo and co-author appropriate of the paper. “From a policy perspective, it is much more efficient and effective.”

The authors also point out that nitrate pollution in lakes and coastal areas has a number of negative socioeconomic consequences. When algal blooms, which are generally considered unlucky and often emit an unpleasant sulfa-like odor, take over a body of water that usually restricts access to sowing. for swimming, sailing and fishing and, as such, have a negative impact on tourism. Toxins associated with algal blooms also limit fishing, and there will be financial problems for inshore fisheries. When cities rely on affected water bodies for drinking water, water treatment costs also rise.

Presented by the University of Illinois Chicago