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Completely updated to keep pace with current technology.
* Provides a firm grounding the fundamentals, theory, and latest techniques.
* Includes completely updated case studies.
We are now in a position to make a substantial contribution to the "greening"
of the planet through ecological engineering and ecosystem restoration. We
find ourselves in a retrospective period of human history, both politically and
ecologically, where although not necessarily questioning all we have built and
engineered to date, we are determining (1) whether to continue practices as
usual (and whether we can afford to do so) and (2) what new approaches are
available for restoring the "bodily functions" of nature, on which we depend.
Signs all around us confirm that a paradigm shift is taking place, both within
and outside the ecological and engineering professions, to accommodate ecological
approaches to what was formerly done through rigid engineering and
a general avoidance of anyreliance on natural systems.
Engineers, ecologists, resource managers, and even politicians are now
completely redesigning, at a cost of almost $8 billion, the plumbing in the
southern Florida Everglades to provide a more ecologically integrated system
(Figure 1.1). As part of the effort in the Florida Everglades, the Kissimmee
River in Florida is being "restored"-at an enormous cost-to something
resembling its former self before it was canalized 30 years ago (Figure 1.2).
Ecological approaches are being investigated to reduce nonpoint-source pollution
from reaching the Baltic Sea, where extensive eutrophication is occurring.
The Gulf of Mexico continues to have annual "dead zones" that now
spread well over 20,000 km², approaching the size of the state of Massachusetts.
Discussions are being held not on whether to restore the Mississippi
River Basin to a more natural state by removing levees and restoring wetlands
and riparian forests (Figure 1.3), but when and how that restoration will occur.
In a related effort, the Louisiana delta and coastline are disappearing into the
sea, and major efforts are under way to reduce land loss along that coastline.
Denmark is bringing back its largest river, the Skern River, to its old meandering
course to prevent continued deterioration of coastal waters (Figure 1.4).
Treating wastewater with constructed wetlands (Figure 1.5), an approach just
begun with experiments in the 1960s and 1970s, is now an accepted approach
for wastewater treatment throughout the world. Thousands of hectares of
coastal marshes are being restored along the Delaware Bay in New Jersey
from hay farms to a status they have not seen since the eighteenth century
by removing dikes and carving tidal creeks (Figure 1.6).
The planners of the expensive and controversial Biosphere 2 enclosed ecosystems
in Arizona (Figure 1.7) have perhaps unwittingly illustrated the
great value of natural ecosystems. In an ecological engineering of the most
extreme kind, a group of ecosystems were designed in a 1.25-ha glass-enclosed
system to illustrate potential use of such enclosed systems for human
support in future space colonies. But fans were used for air movement instead
of natural air movement and pumps for water movement to replace the free
water flow from the hydrologic cycle, illustrating exactly the point of this
book: Ecosystems, running on the natural energies of sunlight, wind, and
water, are our real support systems, providing a great variety of free public
service functions that we do not realize are important until they are gone.
Costanza et al.'s (1997) classic answer to the question "what is nature
worth?" suggested that ecosystems are providing services equivalent to about
$64,000 per square kilometer per year. By using the cost of construction and
maintenance of Biosphere 2 as an indicator of what it would take to produce
ecosystems devoid of our climate, air, water, and winds, the value of an
ecosystem escalates to about $1 billion per square kilometer per year (Mitsch,
1999). This is the cost we would incur to create our natural Earth in space,
forgetting the cost to get there. The message of these estimates is of course
clear: We should protect and enhance our Biosphere 1, allowing it to provide
the services it provides and, in some cases, enhancing its ability to provide
Ecologists are now refining the techniques of restoring function in degraded
ecosystems, and countless ecologists now call themselves restoration ecologists.
Agricultural engineers, known for the efficiency with which they drained
the landscape, are changing their names and their actions in many locations
by restoring ditches to stream channels and farmlands to wetlands. Civil engineers,
the nation's top river straighteners, are busy removing dams and
restoring river meanders. The U.S. Army Corps of Engineers is now "greening"
its mission to specifically include ecological restoration; some in that
organization see themselves not only as the nation's water resource managers,
but also as the nation's ecological engineers. Restoration and creation of ecosystems
is now an industry.
1.1 FORTY YEARS OF ENVIRONMENTAL PROTECTION AND
We are approaching an age of diminishing resources where the growth of the
human population continues and we have not yet found the proper means to
solve local, regional, and global pollution and shortage of renewable resources.
The first green wave that appeared in the middle and late 1960s was
thought to offer feasible ways to solve pollution problems completely. Visible
problems were mostly limited to point sources of air and water pollution and
a comprehensive "end-of-the-pipe technology" (i.e., environmental technology)
was developed and refined in that time to solve pollution problems. It
was even seriously forecast in the early 1970s that what was called zero
discharge could be attained for water pollution. For example, the U.S. Congress
declared in the Clean Water Act in 1972 that all waters of the nation
should be fishable and swimmable by 1983. The year came and went, yet
half the rivers in the country were not "fishable and swimmable" as the act
had stipulated just because the politicians said it should be. There were complications
far beyond controlling industrial and municipal wastewater.
It became clear that zero-discharge or similar policies would be too expensive
and that we should also rely on the self-purification ability of ecosystems.
That outlook called for the development of environmental and
ecological models to assess the self-purification capacity of ecosystems and
to set up emission standards reflecting the relationship between impacts and
effects in the ecosystems (Figure 1.8). In this case, models were used to relate
an emission to its effect on the ecosystem, and toxicological studies were
used to determine the effects on its components (e.g., fish). Those relationships
were then used to determine a good solution to the environmental problems
by application of environmental technology (e.g., wastewater treatment
Meanwhile, we have found that what we could call the environmental crisis
is much more complex than thought. We could, for instance, remove heavy
metals from wastewater, but where should we dispose the sludge containing
the heavy metals? Resource management pointed toward recycling instead of
removal. Nonpoint sources of toxic substances and nutrients, originating primarily
from agriculture, emerged as new threatening environmental problems
in the late 1970s. The focus on global environmental problems such as acid
deposition, the greenhouse effect, and the decomposition of the ozone layer
in the 1980s added to the complexity of the situation. It was revealed that we
use as many as 100,000 chemicals that may threaten the environment, due to
their more-or-less toxic effects on plants, animals, humans, and entire ecosystems.
In most industrialized countries, comprehensive environmental legislation
was introduced to regulate the wide spectrum of different pollution
sources. Trillions of dollars have been invested in pollution abatement on a
global scale, but it seems that two or more new problems emerge for each
problem that we solve. Our society seems not to be geared to solving environmental
problems, or is there perhaps another explanation?
The complexity and additional options of today's environmental management
includes simultaneous application of environmental technology, cleaner
technology, environmental legislation, ecological engineering, and ecosystem
restoration (Figure 1.9). Traditional environmental technology offers a broad
range of methods that are able to remove pollutants from water, air, and soil,
and these methods are particularly applicable to cope with point sources.
Cleaner technology explores the possibilities of recycling by-products or final
waste products or attempts to change the entire production technology to
obtain reduced emission. It attempts to answer the pertinent question:
Couldn't we produce our product by a more environmentally friendly method?
To a great extent, the answer will be based on environmental risk assessment,
life-cycle analysis, and environmental auditing. The ISO 14000 series and
risk reduction techniques are among the most important tools in the application
of cleaner technology. Environmental legislation and green taxes may
be used in addition to the classes of technology. The fourth option-ecological
engineering and ecosystem restoration combined-is the subject
of this book.
Figure 1.10 shows the flows of material (and energy) in the history of a
product, from raw materials to final disposal as waste. The exact number of
products in modern technological society is not known, but it is probably on
the order of [10.sup.7] to [10.sup.8] . All these products emit pollutants to the environment
during their production, transportation from producer to use, application, and
final disposal as waste. The core problems in environmental management are
how to control pollutants properly and how to manage our ecological systems
in this less-than-perfect world. The answer is that we must have a wide spectrum
of methods. Notice that Figure 1.10 is based on the principles of conservation
of matter and energy and on our wider use of ecosystem properties
in environmental management. Environmental legislation and green taxes are
not included in Figure 1.10, as they may in principle be used as regulating
instruments in every step of the flow from raw materials and energy to final
waste disposal of the product used.
From this short introduction to environmental management and the wide
spectrum of methods that can be implemented to solve environmental problems,
we can conclude that environmental management is a very complex
issue. A local environmental problem may be solved by selection of another
raw material or energy source, by a partial or complete change in the method
of production, by increased use of recycling, by selection of the proper combination
of technological methods taken from any of the four aforementioned
classes of technologies, by a slight change in the properties of the product,
by a combination of environmental technology with recovery of the ecosystem
affected, and so on. The number of possible solutions is enormous, yet the
environmental management strategy should attempt to find the optimum solution
from an economic-ecological point of view.
Two major forces can lead to apathy: naive technological optimism-the
idea that some technological wonder will always save us regardless of what
we do, and gloom and doom pessimism-the idea that nothing will work and
our destruction is assured. Ecological and environmental problems are very
complex and difficult to solve. The best starting point to solving the complex
and difficult problems must be an understanding of the nature of the problems.
Ecological principles and ecological methods can then be employed to solve
some of them.
1.2 WHY ECOLOGICAL ENGINEERING AND RESTORATION ARE
The state of our environment, combined with a dwindling in nonrenewable
natural resources available to solve environmental problems, suggests that the
time has come for a new paradigm that involves ecosystem- and landscape-scale
questions and solutions. There are a great number of environmental and
resource problems that need an ecosystem approach, not just a standard technological
solution. We have finally recognized that we cannot achieve complete
elimination of pollutants, owing to a number of factors, and that we
need new approaches better attuned to our natural ecosystems. In our attempts
to control our own environment, we have also seen that we have tried to
control nature too much at times, with disastrous consequences such as enormous
floods, invasive species, air and water pollution being transported hundreds
and thousands of kilometers instead of a few kilometers, and the
production of massive quantities of solid wastes that need disposal or use
somewhere. But why now, and why do we suggest this new field, especially
to include engineers, whom many blame for the difficult situation in which
we now find ourselves?
There is a finite quantity of resources to address to the problems of pollution
control and natural resource disappearance. This is particularly true for developing
countries that wish to have the standard of living and technology of
developed countries but currently must deal with pollution problems often
more serious than those in the developed world. The limited resources and
the high and increasing human population force us to find a trade-off between
the two extremes of pollution and totally unaffected ecosystems. We cannot
and must not accept a situation of no environmental control, but neither can
we afford zero-discharge policies, knowing that we do not provide one-third
of the world's population with sufficient food and housing.
Three pronounced developments have caused the environmental crisis that
we are now facing: the growth in population, industrialization, and urbanization.
Figure 1.11 illustrates world population growth, past and projected.
From the graph it can be seen that population growth has experienced decreasing
doubling time, which implies that growth is more than exponential
(exponential growth corresponds to a constant doubling time). The growth of
population from 1 billion to 2 billion people took about 100 years, whereas
the next doubling in population took only 45 years. The net birth rate at
present is about 370,000 people per day, while the death rate is 150,000 per
day. The population growth is determined by the differences between the two:
population increase = birth rate - death rate. The present growth rate implies
that the world's population is increasing by more than 200,000 people per
day, or about 1.5
Excerpted from Ecological Engineering and Ecosystem Restoration
by William J. Mitsch Sven Erik Jorgensen
Copyright © 2003 by William J. Mitsch, Sven Erik Jorgensen.
Excerpted by permission.
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
Excerpts are provided by Dial-A-Book Inc. solely for the personal use of visitors to this web site.
1. Why Ecological Engineering and Ecosystem Restoration.
3. Classification of Ecological Engineering.
5. Ecological Design Principles.
'II. APPLICATIONS OF ECOLOGICAL ENGINEERING.
6. Lake and Reservoir Restoration.
7. STream and River Restoration.
8. Wetland Creation and Restoration.
9. Coastal Restoration.
10. Treatment Wetlands.
11. Bioremediation: Restoration of Contaminated Soils.
12. Mine and Disturbed Land Restoration.
13. Ecological Engineering in China.
III. ECOLOGICAL ENGINEERING TOOLS.
14. Modeling in Ecological Engineering and Ecosystem Restoration.