Page 435 - Environment: The Science Behind the Stories

Wildlife Sanctuary has brought the town’s waterfront back to
life; more than 100,000 people visit each year, and over 300
species of birds have been observed there. The practice of
treating wastewater with artificial wetlands is growing fast;
today over 500 artificially constructed or restored wetlands
in the United States are performing this service.
The release of wastewater effluent even shows prom-
ise for preserving coastal wetlands along the Gulf Coast. At
a study site in Louisiana, wastewater effluent was released
into coastal wetlands, where it enhanced growth in marsh
grasses due to the effluent’s elevated nutrient concentrations.
The increased plant growth led to increased deposition of
plant organic matter on marsh sediments, offsetting the depth
increases caused by natural soil compaction.

Conclusion
Figure 15.27 The Arcata Marsh and Wildlife Sanctuary is
the site of an artificially engineered, constructed wetland
system. The wetlands help treat this northern California city’s Citizen action, government legislation and regulation, new tech-
wastewater, and upland areas around the marsh are open to the nologies, economic incentives, and public education are all help-
public for recreation. ing us to confront a rising challenge of our new century: ensuring
adequate quantity and quality of fresh water for ourselves and
for the planet’s ecosystems. Accessible fresh water comprises a
One of the first constructed wetlands was established minuscule percentage of the hydrosphere, but we generally take
in Arcata, a town on northern California’s scenic Redwood it for granted. Our expanding population and increasing water
Coast (Figure 15.27). This 35-ha (86-acre) engineered wet- use are bringing us toward conditions of widespread scarcity.
land system was built in the 1980s after residents objected Water depletion has become a serious concern in many areas of
to a $50 million system plan to build a large treatment plant the developing world and in arid regions of developed nations.
and pump treated wastewater into the ocean. In the wetland Water pollution, meanwhile, continues to take a toll on the
system that was built instead, oxidation ponds send partially health, economies, and societies of nations both rich and poor.
treated wastewater to the wetland, where plants and microbes Better regulation has improved water quality in the United States
continue to perform secondary treatment. The project cost and other developed nations, and there is reason to hope that we
just $7 million, and the site also serves as a haven for wild- may yet attain sustainability in our water use. Potential solutions
life and human recreation. In fact, the Arcata Marsh and are numerous, and the issue is too important to ignore.

Reviewing objectives

you should now be able to: • We use water for agriculture, industry, and residential use.
Globally, 70% is used for agriculture. (p. 415)
Describe the distribution of fresh water on Earth and • We pump water from aquifers and surface water bodies,
the major types of freshwater systems sometimes at unsustainable rates. (pp. 415–417)

• Of all the water on Earth, only about 1% is readily avail- • Some of our water extraction now goes to bottled water,
able for our use. (p. 409) which is hugely popular even though it is no healthier than
tap water and creates substantial plastic waste. (pp. 417–418)
• Groundwater is contained within aquifers. (pp. 409–411)
• We attempt to control floods with dikes and levees. (pp.
• A watershed is the area of land drained by a river system. 418–420)
(p. 411)
• We divert water with canals and irrigation ditches to bring
• The main types of freshwater ecosystems include rivers water where it is desired. (pp. 420–421)
and streams, lakes and ponds, and wetlands. (pp. 411–414)
• We have dammed most of the world’s rivers. Dams bring a
diversity of benefits and costs. (pp. 421–422)
Discuss how we use water and alter freshwater
systems • Some dams are now being removed. (p. 422)
• Water is a renewable but limited resource, so we must man- • Many wetlands have been lost, and we are now trying to
434 age it sustainably. (p. 414) restore some. (pp. 422–423)

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