Environmental Engineering Reference
In-Depth Information
called “urban stream syndrome,” which in part describes the consistently observed down-
cutting of streams draining urban lands. Increased volume and velocity of runoff from
impervious surfaces results in stream downcutting and disconnects riparian areas, scours
streambed surfaces, and reduces invertebrate and fish habitat (
Walsh et al. 2005
).
Urban ecology will drive ecosystem scientists to ask new kinds of questions, analyze new
kinds of data, and include humans in their conceptual frameworks (
Figure 17.2
). In addition
to asking questions about the distribution of organisms in and around cities and biogeo-
chemical budgets of urban watersheds, urban ecosystem science will increasingly combine
ecological data with land-use/land-cover data, economic and census data, and social
surveys to understand not only how urban ecosystems function ecologically, but their
socio-ecological interactions as well. Integrating humans into ecological theory will allow us
to ask questions such as how landscaping choices affect the types of bird species in urban
areas, how household and authority decisions influence the fluxes of nitrogen and carbon,
how to control the proliferation of invasive species in urban areas, and the consequences of
new contaminants associated with dense populations.
Contaminants of Emerging Concern and New Technologies
Safeguarding and maintaining high-quality water, air, and soil represent some of the
largest challenges facing humankind. Although advances in technology have allowed
the developed world to keep pace with agricultural and health demands, they have also
introduced new sources and types of pollution (e.g., insecticides, fungicides,
pharmaceuticals, and personal care products). Toxins associated with manufacturing,
energy extraction, pest control, and wastewater are discharged into aquatic systems,
released into the air, and sprayed onto landscapes. The ecosystem effects of some of
these compounds are well known, but the effects of others are just now being investi-
gated or have not been studied at all. Thus, assessing and minimizing the environ-
mental impact of these compounds will occupy much of ecosystem science in coming
decades.
Understanding the influence of anthropogenically derived compounds on the environ-
ment is a continuing challenge for future research. Great strides have been made
to understand the effects of global contaminants such as DDT, PCBs, mercury, and
ozone-depleting CFCs, but the influence of other common human-derived compounds
on ecosystems remains unknown. New investigations of pharmaceuticals discharged
into aquatic systems have found that they can affect the function of organisms (e.g., fish,
amphibians, and invertebrates) by suppressing growth, altering gender, and changing
behavior and physiology. However, the effects of pharmaceutical compounds on
ecosystem processes, such as alteration of gross primary production or decomposition
rates, remain largely unknown (
Rosi-Marshall and Royer 2012
). Also, new emerging
micropollutants may present risks and management challenges. For example, nanotech-
nology, the art of manipulating matter at the atomic or molecular scale, is expected
to have wide-reaching consequences for society and for ecosystems. Though nanoparti-
cles (silver, titanium, gold, and zinc, but also carbon and silicon) have been developed
to improve properties of a wide variety of products and services (e.g., cosmetics,
