Page 371 - Environment: The Science Behind the Stories

THE SCIENCE BEHIND THE STORY

Baltimore and The fast flow of water also
Phoenix Showcase worsens pollution. In natural areas,
streams and wetlands filter pollution by
Urban Ecology breaking down nitrogen compounds.
But in urban areas, where wetlands
Researchers in urban ecology examine dry up and runoff from pavement cre-
how ecosystems function in cities and ates flash floods, streams lose their
suburbs, how natural systems respond filtering ability. In Baltimore, the resulting
to urbanization, and how people inter- pollution ends up in Chesapeake Bay,
act with the urban environment. Today, which suffers eutrophication and a large
Baltimore and Phoenix are centers for hypoxic dead zone (pp. 123, 126–127).
urban ecology. Baltimore-project scientists studying
These two cities are very different: nutrient cycling (p. 135) found that
Baltimore is an Atlantic port city on An urban ecologist samples water urban and suburban watersheds have
beneath an overpass in Baltimore.
Chesapeake Bay with a long history, far more nitrate pollution than natural
whereas Phoenix is a young and forests (FIGURE 1).
fast-growing Southwestern metropolis the past 100 years, even while the Baltimore research also reveals that
sprawling across the desert. Each was overall amount of forest remained the applying salt to icy roads in winter has
picked by the U.S. National Science same. environmental impacts. Road salt makes
Foundation to serve as a research The study regions designated for its way into streams, which become up
site in its prestigious Long Term each city encompass both heavily
Ecological Research (LTER) program, urbanized central city areas and rural Agricultural area
which funds multi-decade ecological and natural areas on the urban fringe. 8 Suburban area
research. Since 1997, hundreds of To measure the impacts of urbaniza- Forested area
researchers have studied Baltimore tion, many research projects com- 6
and Phoenix explicitly as ecosystems, pare conditions in these two types of mg nitrate per liter
examining nutrient cycling, biodiver- areas. 4
sity, air and water quality, how people The Baltimore project’s scientists
react to environmental health threats, can see ecological effects of urbani- 2
and more. zation just by comparing the urban
Research teams in both cities lower end of their site’s watershed 0
are combining old maps, aerial pho- with its less-developed upper end. In 2000 2001 2002 2003 2004 2005
tos, and new remote sensing satellite the lower end, pavement, rooftops, Year
data to reconstruct the history of and compacted soil prevent rainfall FIGURE 1 Streams in Baltimore’s suburbs
landscape change. In Phoenix, one from infiltrating the soil, so water runs contain more nitrates than streams in
group showed how urban develop- off quickly into streams. The rapid nearby forests, but fewer than those in
ment spread across the desert in a flow cuts streambeds deeply into agricultural areas, where fertilizers are
“wave of advance,” affecting soils, the earth while leaving the surround- applied liberally. With kind permission from
vegetation, and microclimate as it ing soil drier. As a result, wetland- Springer Science and Business Media and the
went. In Baltimore, mapping showed adapted trees and shrubs are author, Groffman, P.M., et al., 2004. Nitrogen
that development fragmented the vanishing, replaced by dry-adapted fluxes and retention in urban watershed ecosys-
tems. Ecosystems 7: 393–403; Fig 4. Also from
forest into smaller patches over upland trees and shrubs. Baltimore Ecosystem Study.

Urban centers foster innovation For instance, research into renewable energy sources is
helping us develop ways to replace fossil fuels. Technological
Cities promote a flourishing cultural life and, by mixing advances have helped us reduce pollution. Wealthy and edu-
together diverse people and influences, spark innovation and cated urban populations provide markets for low-impact goods,
creativity. The urban environment can promote education and such as organic produce. Recycling programs help reduce the
scientific research, and cities have long been viewed as engines solid waste stream. Environmental education is helping people
of technological and artistic inventiveness. This inventiveness choose their own ways to live cleaner, healthier, lower-impact
can lead to solutions to societal problems, including ways to lives. All these phenomena arise from the education, innova-
370 reduce environmental impacts. tion, science, and technology that are part of urban culture.

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