Agriculture-Caused ‘Dead Zone’ Threatening Gulf of Mexico

(CN) – Ocean life and our supply of clean drinking water will decrease unless more is done to limit farmland runoff of nitrogen-based fertilizer and livestock waste, according to a study published Monday in Proceedings of the National Academy of Sciences.

The nitrogen that washes into rivers and eventually out to sea is necessary for the growth of plant life, but excessive amounts found in the Gulf of Mexico and other places create areas known as dead zones. Excess nitrogen leads to exponential algae growth, which in turn causes an increase of bacteria that decomposes the algae and exhausts all the nearby oxygen. These dead zones choke off all other oceanic life and form algae blooms that are toxic to humans.

Scientists and the National Oceanic and Atmospheric Administration have been working on ways to cut down on nitrogen runoff, but Monday’s study suggests such actions aren’t enough. The Gulf of Mexico is expected to form a dead zone this summer the size of New Jersey, about 8,000 square miles, according to NOAA. An intergovernmental panel wants to reduce it to the size of Delaware, about 1,950 square miles, by 2035.

Researchers estimate nitrogen runoff into the Gulf of Mexico needs to be reduced by 59 percent.

“The bottom line is that we will never reach the action plan’s goal of 1,950 square miles until more serious actions are taken to reduce the loss of Midwest fertilizers into the Mississippi River system,” University of Michigan aquatic ecologist Don Scavia said.

The study reveals that hardly any progress has been made to reduce the amount of nitrogen runoff. Concentrations of the nitrogen compound nitrate found in rivers are the same today as in the 1980s. Despite more than $28 billion in government spending to reduce nitrogen runoff, there has been no significant reduction in the amount of nitrate washing away to the Gulf of Mexico.

“Clearly something more or something different is needed,” Scavia wrote in the study. “It matters little if the load-reduction target is 30 percent, 45 percent or 59 percent if insufficient resources are in place to make even modest reductions.”

Researchers suggest that the agriculture sector needs to make significant changes in order to protect ocean life, including the pursuit of alternatives to corn-base biofuels since corn requires a lot of nitrogen and other soil nutrients.

“It is time to ask what is preventing more extensive implementation of some or all of these strategies,” the researchers said.


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