Making the Connections...

Nutrient pollution and eutrophication are strongly linked with other global environmental issues like climate change, air pollution and acid rain. Policymakers should exploit the linkages between eutrophication and other local, regional, and global environmental issues and identify those policies that minimize tradeoffs and maximize environmental benefits. Combustion of fossil fuels, for example, emits nitrogen oxides (NOx), which can be a significant source of nutrient pollution to aquatic ecosystems through the process of atmospheric deposition (Spokes and Jickells 2005).

Fig 1. Forested buffers along streams filter nutrients and sediments before they reach surface waters. These buffers also create habitat, stabilize streambanks and sequester carbon.

Image Credit: Peggy Grebb | U.S. Department of Agriculture

NOx also contributes to other environmental problems such as acid rain and smog. In addition to NOx, combustion of fossil fuels also releases significant amounts of carbon dioxide into the atmosphere—the gas that is primarily responsible for climate change. Policies aimed at reducing combustion of fossil fuels through energy conservation, energy efficiency, and promotion of alternative energy thus have multiple environmental and public health benefits (Moomaw 2002).

Another area with considerable environmental synergies is agricultural policy (Greenhalgh and Sauer 2003). Agricultural policies aimed at providing incentives to farmers to install and implement improved nutrient management on their farms often have several environmental benefits beyond improved water quality. Best management practices that reduce nutrient runoff can also improve wildlife habitat, reduce soil erosion, sequester carbon dioxide, and reduce emissions of nitrous oxide, a greenhouse gas with a warming potential 281 times greater than carbon dioxide (EPA 2009b).

Fig 2. Compost production from organic waste in Batam, Indonesia. This is part of a sustainable development scheme aiming to limit land-based pollution in the South China Sea. Farmers collect and treat organic wastes to produce fertilizer which can then be used on their crops and as an additional source of income.

Image Credit: UNEP 2007

In contrast, policies aimed at mitigating eutrophication that are narrowly focused on regulating wastewater treatment plants have very few environmental co-benefits. In fact, many of the advanced nutrient removal technologies that would be installed by wastewater treatment plants use significantly more energy—which, depending on the method of energy generation, may lead to greater emissions of NOx and carbon dioxide—and possibly emit a significant portion of the captured nitrogen into the atmosphere through volatilization (Foley et al 2007). While primary and secondary treatment of sewage discharges from wastewater treatment plants is important for human health, it is necessary for policymakers to weigh tradeoffs of advanced tertiary treatments and ensure that the selected policies adequately consider the various sectors, sources of nutrient pollution, and other environmental issues.

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