Scientists fear the Midwest’s new fluctuating weather patterns will exacerbate an old problem: nitrate contamination.
In states like Minnesota, Kansas, Iowa and Oklahoma, nitrate — a component in many common synthetic fertilizers that can cause serious illness in infants — has long posed a problem for local water supplies. The Midwest provides the perfect conditions to carry nitrogen into the water table: a relatively shallow groundwater level, porous soils that allow the fertilizers to leach through and more cultivated fields than woodlands.
With climate models predicting the region will increasingly swing between droughts and heavy downpours, researchers say the situation threatens to deteriorate.
“During a good year, most of the fertilizers that farmers add to their fields go to the crops. But during a drought, the crops don’t grow as much, and so they don’t suck up as much nitrogen. What we end up with is more nitrogen stored in the soil, and if the drought ends with heavy precipitation, it’s quickly washed into the water,” explained Terry Loecke, an assistant professor of environmental studies at the University of Kansas.
Locke and his colleague Amy Burgin, an associate professor of environmental studies at the University of Kansas, pulled up data on droughts and floods over the last decade or so. They found the sequence corresponded fairly often with skyrocketing nitrate levels in both rivers and groundwater.
It’s likely, they say, that this pattern will continue to get worse. While the degree of contamination could vary from state to state depending on the hydrology of the region, cities like Des Moines, Cedar Rapids and Peoria, Iowa, are all vulnerable. Des Moines, in fact, recently constructed a $4.1 million nitrate removal plant after high levels of nitrogen were discovered in the Des Moines and Raccoon rivers.
In Wisconsin, researchers are coming to the same conclusions.
“Nitrates are pretty mobile, so they move easily through the soil into groundwater. In places like Wisconsin, most of our rivers and streams are supplied by groundwater, so the nitrates are exported to the surface,” said Kevin Masarik, a groundwater education specialist with the University of Wisconsin’s Center for Watershed Science and Education.
Masarik has previously modeled the impact of droughts and rainfall on nitrate contamination, and his findings correspond with Loecke and Burgin’s: The combination of a wet year followed by a dry one offers the perfect conditions for nitrate to leach into the groundwater.
“We’re heavily dependent on groundwater — more so than other states — as the primary supply for municipalities as well as rural homeowners, who rely on wells. So with elevated nitrate in the water, we have to worry about issues like treatment,” he said.
Treatment, while necessary, can be expensive. The plant in Des Moines costs about $7,000 per day to operate; as more cities set up facilities to filter nitrates, the cost will probably fall on taxpayers, said Loecke.
“A city can’t predict how many days they’ll have to run a nitrate-removal facility. When they run it a lot, it’s a huge hit to their budget, and they have to pass it on to their citizens, and it will spread out to rest of the Midwest. Midwesterners will have to pay more for drinking water going forward,” he added in a statement.
Without treatment, nitrogen-laden drinking water can cause a host of problems to local ecosystems, ranging from producing more algae and starving water bodies of oxygen to harming fish populations. It’s also responsible for “blue baby syndrome,” a condition that prevents infants from being able to breathe properly.
“Blue baby syndrome got a lot of attention in the late ’70s and early ’80s — it’s when infants consume high-nitrate water, which then interacts with the blood and causes them to suffocate and turn blue,” said Burgin.
While the condition isn’t as common now, she added, researchers don’t know how long-term exposure to nitrogen could affect human health.
Apart from setting up removal facilities, one way to reduce the intensity of the problem could be reforming agricultural practices, said Loecke: for instance, providing farmers with market signals to help keep nitrates out of the water and introducing better forecasting systems.
“That would be extremely helpful, as it would allow farmers to use information in real time to make better decisions about how they use their fertilizer,” he said.
Reprinted from Climatewire with permission from E&E News. E&E provides daily coverage of essential energy and environmental news at www.eenews.net.