Chemical agriculture runoff destroying fresh water with toxic algae blooms

Monday, October 03, 2016 by: David Gutierrez, staff writer
Tags: algal blooms, dead zones, fertilizer runoff

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(NaturalNews) Chemical fertilizers are destroying our supplies of clean water by feeding blooms of toxic algae, scientists and water officials have warned.

The problem has come into sharp focus recently as lakes across California have been closed due to blooms of cyanobacteria, also known as blue-green algae. When they grow, cyanobacteria can produce chemicals that can cause skin rashes and other allergic reactions in people who come into the contact with the water, and gastrointestinal upset in people who drink it. The water is even more dangerous to other species, and drinking even a small amount can kill dogs, livestock and wildlife.

Cyanobacterial blooms are estimated to affect about 40 separate California lakes and waterways this year, nearly double last year's figure of 22. This represents the most bodies of water ever affected.

How fertilizer turns into poison

Although algal blooms are a problem worldwide, California has been particularly hard hit this year, coming off a five-year drought. Cyanobacteria favor still, shallow, warm waters – conditions that were created over the past five years statewide.

Ironically, the recent outbreak of blooms followed a wetter year. That's because in nature, cyanobacteria don't tend to form massive blooms except in very small ponds. The modern phenomena of entire lakes being taken over stems directly from the practice of spreading large quantities of nitrogen- and phosphorus-rich fertilizers over agricultural fields (as well as concentrating livestock – and their manure – onto factory farms). These fertilizers eventually run into local waterways, providing naturally occurring cyanobacteria with a major boost.

Five years of drought meant that fertilizers were not washing off California's agricultural fields as regularly, and were instead building up. The return of the rains this past year caused several years worth of fertilizer to wash into local waterways in just one season. The cyanobacteria reacted with a predictable population boom.

There is evidence that feeding cyanobacteria with fertilizer also makes it more dangerous – which would explain why our ancestors rarely got sick drinking water from lakes and streams. According to a 2009 document by the California Office of Environmental Health Hazard Assessment, higher phosphorus levels cause cyanobacteria to produce more toxins. A 2011 study conducted by researchers from the University of North Carolina-Chapel Hill found similar results, and suggested that high nitrogen concentrations may also boost toxin production.

Ocean life also being killed

Fertilizer-fed algal blooms are also a major problem for the ocean, with impacts for wildlife, fisheries and even beachgoers. A 2010 PLoS ONE study found that the deaths of 21 endangered southern sea otters in California's Monterey Bay were caused by consumption of cyanobacteria that had washed into the ocean from rivers and streams.

Different species of algae are also capable of blooming in the ocean itself. One such species gives rise to the blooms known as red tides, which poison wildlife and can cause deadly disease in people who eat affected shellfish.

Algal blooms are also responsible for the phenomenon known as "dead zones" – areas off the coast that are devoid of life. Dead zones are caused when fertilizer runs off into the ocean, triggering massive algal blooms. These blooms then sink, where they are consumed by bacteria. The population boom among these bacteria causes them to consume so much oxygen that the area they inhabit becomes unable to support life.

Every summer, a dead zone larger than the state of Massachusetts forms in the Gulf of Mexico. Scientists believe it is caused by large-scale agricultural runoff from the Mississippi River.

While the problems leading to algal blooms are largely societal, individual citizens can take action to keep from making the problem worse.

"Any efforts to prevent nutrients from running off of lawns, pastures, or agricultural fields will reduce the frequency and severity of toxic blue-green algae blooms," the 2009 Office of Environmental Health Hazard Assessment fact sheet reads.

Sources for this article include:

EastBayTimes.com

SanFrancisco.CBSLocal.com

ScienceDaily.com