Challenges of the 21st Century - Science For Environmental Protection: The Road Ahead - page 30

address chronic water-quality deterioration, but it has proved elusive even
there.
Nutrient (nitrogen and phosphorus) pollution is one of the more persistent
and pervasive environmental problems in the United States, and it is worsening in
many locations (Howarth 2008). The volume of nutrients reaching surface water
and groundwater has increased substantially since the middle of the 20th century
as a result of a complex of factors, including population growth, changes in land
cover, increased fossil fuel combustion, and changes in the structure of agricultural
production (Selman et al. 2008). Providing the scientific foundations for the de-
velopment of policies that can reduce nutrient-pollution problems will require in-
novative economic, social-science, and natural-science research. The challenges
are particularly difficult because the hydrologic, ecologic, economic, and social
processes affecting the magnitude and scope of nutrient pollution and its conse-
quences are complex, multi-scaled, and spatially variable. To deal effectively with
this complex problem, a framework for incorporating human and environmental
interactions, such as the Millennium Ecosystem Assessment framework (see
Chapter 1) would prove useful. Nutrient pollution should be approached from a
broad perspective that uses systems thinking (see Chapter 4) and there are exam-
ples in which EPA is already taking steps in this direction with the Chesapeake
Bay Program and the New York-New Jersey Harbor Estuary Program. The prob-
lem may not be getting progressively worse, but there are still many challenges to
attaining further improvements. The prospects are that eutrophication will con-
tinue to be a challenge until policies to control nutrients are made more effective
(Cary and Migliaccio 2009; Spiertz 2009).
FIGURE 2-1 Sources of phosphorus and nitrogen in the Gulf of Mexico and Chesapeake
Bay. Source: EPA 2010b.