NRC calls for new approach to livestock emissions The U.S. EPA’s method of estimating emissions of air pollutants from animal feeding operations is not scientifically credible, according to a report released in December from the National Academies’ National Research Council. The report recommends a process-based model that calculates emissions based on factors such as the diet and housing of animals. The report concludes that management practices to cut air emissions should be implemented immediately and outlines promising policies, among which is a nitrogen cap and trading program and financial incentives to use fertilizers more efficiently. Although farms have been largely exempt from the Clean Air Act provisions, EPA has been under increasing pressure to regulate air pollutants from animal feeding operations, says the report. Animals and manure on farms are a significant source of air pollution, generating roughly 50% of emissions of ammonia related to human activity. The ammonia, in turn, drives aquatic nutrient pollution and helps form health-damaging particulates in air, says Jamie Jonker, director of the study. The EPA needs to accurately model emissions from animal farms if it is going to define and support regulation of farm air pollutants, the report says. But EPA’s current method of calculating releases for farms, which is based on average emissions per animal unit, is wrong because it does not capture factors—such as type of feed and manure management—that affect emissions, says Perry Hagenstein, chair of the report panel. Instead, EPA should adopt a process-based model with massbalance constraints that describes inputs and outputs of constituents, such as nitrogen, at each step in the system, from raising crops to feed-
ing animals to disposing of manure, Hagenstein says. For instance, mathematical models can describe the amount of ammonia volatilized from animal housing, manure storage, and manure spreading, he says. Presently, no incentives are provided to reduce farm air emissions, says Rick Kohn, animal nutritionist at the University of Maryland and one of the report’s authors. In fact, EPA’s new manure rules to protect water quality, introduced in December, actually create incentives to make air emissions worse, he says. The focus on preventing releases to water will encourage farmers to spread manure on fields where excess ammonia will volatilize to the air. A better way is to create incentives for farmers to use nitrogen as efficiently as possible, as is the case with the Netherlands’ nitrogen cap and trading program, Kohn says. There, farmers are required to calculate a mass balance equation for nitrogen on their farms. By subtracting nitrogen outputs, such as animal products and manure, from nitrogen inputs, including fertilizer and feed, farmers can calculate how much nitrogen was lost to the environment. Each farm is given an emission threshold, and farmers pay a tax for exceeding the threshold, or they can sell emission credits by staying below the cap. The report describes a host of incentives and technologies to reduce air pollution from farms that have also been cited in the literature (Environ. Sci. Technol. 2002, 36, 1141–1146). Incentives combined with voluntary measures, including reducing the amount of protein in animal feed, adding aluminum sulfate to manure, and tilling manure into the soil, can reduce ammonia emissions by 10–40%, says Donald McCubbin, analyst with Abt Associates, Inc., in Bethesda, Md. —JANET PELLEY
News Briefs EU may not make Kyoto targets Under a business-as-usual scenario, the European Union will fall 3% short of its Kyoto Protocol target of reducing greenhouse gas (GHG) emissions by 8% by 2010, according to the European Commission’s annual report on the subject. The report found that total GHG emissions were down by 3.5% in 2000 compared to 1990. Carbon dioxide emissions fell by 0.5%, methane by 16%, and nitrous oxide by 20% in this period. GHG emissions per capita decreased from 11.5 tonnes in 1990 to 10.8 tonnes in 2000. However, all Member States, except Finland, show large increases in transport emissions. The report predicts under existing measures, emissions will rise by 28% by 2010. The report is based on data from the European Environment Agency (http://reports.eea.eu.int/ report_2002_1205_091750/en/tab_ content_RLR).
2002 second hottest year While 1998 remains the warmest year on record, 2002 surpassed 2001 to earn the number-two spot, according to the World Meteorological Agency. The United Nations agency reports 9 of the 10 warmest years since 1987 came after 1990. The extreme weather events of 2002 included flooding of historic proportions in central Europe, and the first drought to affect the entire country of India since 1987. The United States also experienced twice the usual number of tropical storms. For more information, visit www.wmo.ch.
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FEBRUARY 1, 2003 / ENVIRONMENTAL SCIENCE & TECHNOLOGY ■ 47 A
