Academic journal article Environmental Health Perspectives

Wrangling Reactive Nitrogen: Strategies for Mitigating Pollution

Academic journal article Environmental Health Perspectives

Wrangling Reactive Nitrogen: Strategies for Mitigating Pollution

Article excerpt

Central California's agricultural bounty, which has stocked grocery shelves across North America for decades, has also stocked the region's groundwater supply with nitrates, according to a two-year study by researchers at the University of California, Davis. (1) Aquifers that provide drinking water for thousands of people regularly exceed the state's nitrate concentration safety limits,' potentially raising the risk of thyroid problems, adverse birth outcomes, circulatory problems, and cancer. (2)

The study goes by the name SBX2 1, after the 2008 California Senate bill (3) that called for the California State Water Resources Control Board to deliver a report on nitrate pollution in drinking water--an issue flagged by the state government some 20 years earlier. (4) Prepared by the UC Davis Center for Watershed Sciences, the report draws data from some two dozen private and government agencies, assembling a database of 100,000 samples from nearly 20,000 wells. The results were formally announced at a 13 March 2012 workshop.

The report concludes that regulatory actions to date have failed to contain nitrate pollution of groundwater, which could in fact grow worse in coming decades. Nevertheless, the authors add, there do exist low-and moderate-cost options that could yet effectively control pollution--provided the appropriate political and industrial will is brought to bear to implement them. "I'm very optimistic that in another twenty years there won't be another report to the legislature," concluded principal investigator Thomas Harter after the three-hour workshop, which included a panel discussion to lay out a wide range of approaches to the problem.

This sentiment was reflected in the Winter 2012 edition of Issues in Ecology, which was subtitled "Excess Nitrogen in the U.S. Environment: Trends, Risks, and Solutions." (5) A team of authors led by Eric A. Davidson, executive director and senior scientist of The Woods Hole Research Center, reported there have been "important successes in reducing nitrogen emissions to the atmosphere, and this has improved air quality." They also noted that effective options have been identified for reducing nitrogen losses from agriculture, "although political and economic impediments to their adoption remain."

What is Reactive Nitrogen Plantation?

The effects of nitrogen pollution can be found everywhere that nitrogen has transformed the air, water, or land. The culprit in each case is reactive nitrogen, meaning any form of the element other than the nonreactive atmospheric gas N2. Where reactions occur, the most common products are nitrous. oxide ([N.sub.2]O), nitrite (N[O.sub.2]), nitrate (N[O.sub.3]), ammonia (N[H.sub.3]), and nitrogen oxides (N[0.sub.x]).

The largest proportion of reactive nitrogen in the environment comes from agriculture. (6) In 1909 the Nobel prize winning German chemists Fritz Haber and Carl Bosch developed the Haber process, which enabled the industrial-scale production of ammonia for use in fertilizer and explosives. Over the next century the price of ammonia plummeted, and the world now uses upward of 400 billion pounds of the stuff every year, most of it winding up on farmer's fields. (7) Other anthropogenic sources of reactive nitrogen include industry, transportation, and electricity generation; natural inputs include lightning and bacterial nitrogen fixation. (5)

A 2007 review by the United Nations Environment Programme and The Woods Hole Research Center showcased the difficulties caused by reactive nitrogen in different settings around the world. (8) Wherever internal combustion engines flourish, for example, they emit large volumes of N[O.sub.x], which has been linked with respiratory disease, diminished heart and lung function, and reproductive problems. (2), (9) Nitrogen compounds also react with other air pollutants to form toxic ozone and particulate matter. (8)

In the developed world, legislative measures requiring manufacturers to limit these emissions have met with noteworthy success. …

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