(CN) – Increased rainfall from a changing climate is likely to negatively impact water quality and will result in more toxic algal blooms, scientists said Thursday.
A consortium of science researchers published a study in Science on Thursday detailing how they used advanced computer models to gauge how water quality will be affected by rising temperatures and increased precipitation.
"Our findings demonstrate that it is imperative that water-quality management strategies account for the impact of future precipitation changes on nitrogen loading," said Anna Michalak, co-author and researcher with the Carnegie Institution for Science.
Michalak and fellow Carnegie scientist Eva Sinha joined with Princeton University's Venkatramani Balaji to concentrate specifically on increased rainfall’s effect on the presence of nitrogen in waterways.
Nitrogen is a common ingredient in fertilizer and is also found in abundance as a remnant from fossil-fuel combustion, meaning increased rainfall could wash an excess of the element into rivers, streams, lakes and the sea.
It’s also food for algae, so the toxic algal blooms that have afflicted Lake Erie and other bodies of water throughout the Midwest could become more frequent and pernicious, the study says.
Dead zones in coastal regions across the United States – including the Gulf of Mexico, Florida and in the Chesapeake Bay – have garnered the attention of journalists, regulators and ordinary citizens.
The study found the nitrogen-loading problem will be particularly pronounced in the Northeast and the Midwest, where fertilizer is used in abundance for the region’s agricultural production.
Aside from an increase in toxic algal blooms, nitrogen-loading in lakes can lead to a process called eutrophication, where lakes lose clarity and become muddy brown, unsightly and full of nutrients that may be harmful to human health.
While land-use management decisions can curtail the amount of nutrients that enters waterways, the study found that the frequency of storm events and heavy precipitation spurred by climate change will play a large role in determining the health of water bodies.
"In the 1970s, we discovered human-caused eutrophication and took steps to reverse its course," said Tom Torgersen, director of the National Science Foundation's Water, Sustainability and Climate program, which funded the research. "As this paper shows, however, even seemingly minor climate variations can result in a return to the eutrophication of the past. Just to stay even, it will take more research to create better management strategies."
The researchers used 21 different climate models to predict how much runoff would occur under three different climate scenarios.
Under the status quo scenario, where greenhouse-gas emissions essentially stay static, models demonstrate the resulting changes in climate would change rainfall patterns in the United States and increase nutrient pollution by one-fifth by the end of the century. The Corn Belt and the Northeast would be particularly affected.
In order to mitigate this effect under the scenario, the regions would have to reduce the use of nitrogen in products like agricultural fertilizer by up to one-third.
While the research concentrated specifically on the United States, the researchers also found similar patterns in China, Southeast Asia and India.
"These are regions that more than half of the world's population calls home, so severe water-quality impairments could have serious impacts on a lot of lives," Sinha said.
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