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1. INTRODUCTION AND OVERVIEW
The hazards to humans and ecosystems from exposure to the high
concentrations of atmospheric pollutants in urban areas are now well
documented, having been the focus of much research. As a result, air
quality considerations are becoming an integral part of urban and
industrial planning.
On the other hand, when some of the same pollutants are
disseminated broadly beyond urban areas, their fates and effects are
still little known. The analytical methods sufficiently sensitive to
measure trace concentrations of many pollutants have been developed
only recently. But even our present rudimentary understanding of
regional and global distribution of atmospheric pollutants, now
coupled with improvements in the scope and sensitivity of toxicity
testing, has produced a number of indications in the scientific
literature suggesting that some pollutants, even when diluted by air
masses on a continental or global scale, may accumulate in the
biosphere to concentrations that may be proved to be harmful.
Organochlorine pesticides and radionuclides from nuclear testing are
among those cited for widespread dissemination and accumulation. More
recently, evidence of other kinds of atmospheric pollution has been
found in rural and even wilderness areas remote from major sources of
atmospheric pollution. Examples are acid precipitation, increased
trace metal deposition, and reduced visibility.
Many lines of evidence have shown that most kinds of atmospheric
pollution have close associations with patterns of intensive human
energy use. The consumption of fossil fuels is known to be the major
source of anthropogenic pollution of the atmosphere, rivalled only by
the high temperature smelting of metallic ores. It is predicted that
energy demands will continue to increase exponentially (NRC 1979), and
fossil fuels will play an important role in satisfying
As a result, the Committee on the Atmosphere and
,
such demands.
the Biosphere decided
to conduct a general review of the pollutants discharged to the
atmosphere from fossil fuel burning.
Some of the effects of pollutants from fossil fuel usage have been
relatively well studied--for example, the postulated linkage between
increasing atmospheric CO2 and climatic warming (NRC 1977a, Kellogg
1
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and Schware 1981~; the damage to vegetation by photochemical oxidants
(NRC 1977b); and the health-related effects of SO2, NOX, and lead
(NRC 1978a,d; 1980a). Therefore, this Committee focused its efforts
on the broad scale ecological effects of SOX and NOX, as well as
on the less well-known trace metal and organic pollutants. Attention
was concentrated on the general properties of pollutants that govern
their emission, dissemination, deposition, and ecological effects in
the hope that discernible patterns would emerge that could assist
management agencies and legislators in foreseeing some of the
environmental consequences of continued fossil fuel burning, and in
devising research programs that will address the most critical of
unknown factors as quickly as possible.
THE FOS SI L FUEL SCENARIO:
THE PROBABILITY OF A CRISIS IN THE BIOSPHERE
Ecologists, geochemists, and climatologists are beginning to
discover that in many respects man is now operating on nature's own
scale, particularly through the heavy use of fossil fuels to supply
the energy that runs our industrial civilization. Because the
uncertainties associated with such large-scale operations are very
great--for good or ill--it behooves us to exercise restraint in our
present intensive use of energy, and to mitigate where possible the
ill effects that air pollution imposes not only on us but also on the
ecosystems that make up our life support system. In this connection
numerous studies have reported on the substantial opportunities for
energy conservation and shifts to alternative energy sources.
The predicted effects of the continued and accelerated combustion
of fossil fuels are many and complicated. Some climatologists
hypothesize that discharge to the atmosphere of CO2 and other
pollutants is likely to change the radiation balance of the earth
sufficiently within the next century or so to cause major warming as
well as changes in the patterns of climate. While there is
considerable uncertainty in predictions, some of the hypothesized
consequences could be severe. Droughts may be caused that are capable
of reducing food production in many areas now providing surpluses for
export. Other areas of the world may become able to produce more food
than before, but many of these currently lack the technology and
capital to do so. The postulated changes in climate would also cause
major changes in many of the earth's natural ecosystems. Moreover,
the hypothesized rise in sea level caused by the melting or breakup of
the Greenland and west Antarctic ice sheets might necessitate the
eventual relocation of major cities (NRC 1977a, Kellogg and Schware
1981), although the time scale is uncertain.
Perhaps the first well-demonstrated widespead effect of burning
fossi1 fuel is the destruction of soft-water ecosystems by "acid
rain," which has been caused by anthropogenic emissions of sulfur and
nitrogen oxides that are further oxidized in the atmosphere. Major
effects include destruction of many species of fish and their prey and
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acidification of surface and ground waters to the point where toxic
trace metals reach concentrations undesirable for human consumption
and for aquatic animal habitats (see Chapter 8~. Severe degradation
of many aquatic ecosystems has been recorded in Norway, Sweden, the
United States, Scotland, and Canada (Drablos and Tollan 1980~.
Surprisingly, significant effects have also been recorded for aquatic
systems in countries once thought to be geologically resistant to
acidification, including the Netherlands, Denmark, and Belgium
(Vangenechten and Vanderborght 1980, Van Dam et al. 1980, Rebsdorf
1980).
Although claims have been made that direct evidence linking
power-plant emissions to the production of acid rain is inconclusive
(Poundstone 1980, Curtis undated), we find the circumstantial evidence
for their role overwhelming. Many thousands of lakes have already
been affected, according to estimates by European and North American
scientists (Drablos and Tollan 1980~. Acidified lakes have been found
in areas where geological factors, such as volcanism and the
weathering of pyrites, or biological factors, such as acid bog
drainage, cannot be implicated. At current rates of emission of
sulfur and nitrogen oxides, the number of affected lakes can be
expected to more than double by 1990, and to include larger and deeper
lakes (Henriksen 19801. There is little probability that some factor
other than emissions of sulfur and nitrogen oxides is responsible for
acid rain. Although the deposited nitrogen and sulfur may be slightly
beneficial in terrestrial soils deficient in these elements, the
stimulus is expected to be short-lived (Abrahamson 1980), and over the
long term acid precipitation is likely to accelerate natural processes
of soil leaching that lead to impoverishment in plant nutrients
(Overrein et al. 1980~. When freshwater effects are considered, the
positive effects are greatly outweighed by the negative.
The same gaseous oxides are known to affect human health directly
in urban areas (Lave and Seskin 1977, NRC 1977b, NRC 1977c, NRC 1978a,
Mendelsohn and Orcutt 1979) and to cause decreases in crop yields in
some areas. Acid deposition is also known to cause large economic
losses by corroding metals and eroding buildings and statuary made of
calcareous rock (Bolin 1971, Nriagu 19781. The Committee believes
that continued emissions of sulfur and nitrogen oxides at current or
accelerated rates, in the face of clear evidence of serious hazard to
human health and to the biosphere, will be extremely risky from a
long-term economic standpoint as well as from the standpoint of
biosphere protection.
Less well appreciated is the widespread dispersal of toxic metals
by the burning of fossil fuel (Bertine and Goldberg 1971, NRC 1980a).
Of most immediate concern are mercury, lead, zinc, and cadmium.
Mercury metal occurs at high concentrations in many fishes under
natural conditions. Its release to the atmosphere through the burning
of coal and crude oil, as well as through smelting, cement
manufacture, and municipal incineration, may already have been
sufficient to elevate mercury concentrations enough to make fish from
many areas unacceptable for human consumption. Lakes and rivers
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containing fish with elevated mercury concentrations have been
reported from Sweden, Quebec, New Brunswick, Ontario, Minnesota, New
York State, and Maine (Tomlinson et al. 1980). Precipitation in areas
receiving acid deposition and high sulfate deposition also has
elevated mercury concentrations (Tomlinson et al. 1980, Semb 1978,
Dickson 1980), and mercury uptake by fish appears to be enhanced by
low pH. At present, there is no satisfactory technology for
controlling large-scale emissions of mercury to the atmosphere. Its
continued or accelerated release, especially in view of its synergism
with acid deposition, may cause chronic problems in many areas in
years to come.
Natural lead releases now have been exceeded by emissions from
man's activities (Lantzy and Mackenzie 1979, NRC 1980a). While data
are scarce, some have argued that the present body burden of lead in
average Americans, and probably in other residents of industrial
societies, is approaching chronically damaging levels (Patterson, see
minority report in NRC 1980a; Settle and Patterson 1980~. Leaded
gasolines are heavily implicated, though other industries are also
important sources of lead (NRC 1980a).
Models based on concentrations in sediment and water and on
projected rates of increases in emissions suggest that in Lake
Michigan both cadmium and zinc will reach concentrations toxic to
zooplankton within the next 30 to 80 years depending on the rate of
increase in emissions of the metals (Muhlbaier and Tisue 1981;
Marshall and Mellinger 1980; G.T. Tisue and J. Marshall, Argonne
National Laboratory, Argonne, IL, personal communication; Figure
1.1~. Many other waters may be similarly affected, although careful
studies have not been done yet to document these changes.
The chronicle of detrimental substances from the burning of fossil
fuel could be continued for many pages, treating--among others
--vanadium, arsenic, copper, and selenium. Also emitted are organic
micropollutants of many types, some of which are known to be
carcinogens, acute toxicants, teratogens, and mutagens. Hence, faced
with the total array of atmospheric pollutants that could be
reviewed--far beyond the scope of one committee's abilities--the
Committee on the Atmosphere and the Biosphere decided to focus its
attention on pollutants generated in energy production, most notably
on sulfur and nitrogen compounds including acid rain, trace metals'
and organic substances. Carbon dioxide, an important pollutant, is
treated in some detail by NRC (1979b), and little space is devoted to
it here.
THIS REPORT
Patterns of emission, transport, deposition, interaction, and
biological effects of energy-related pollutants are known only
incompletely, and we were forced to use a mosaic of examples to
illustrate different concepts. We hope that this review will provide
a preliminary guide to the sorts of integrated research needed to
overcome weaknesses in our understanding of the consequences of
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1 ' 1 1 1
l ~ ~ l ~
105
104
0
A 103
-
UJ
=5 10'
Cal
10°
0% per annum
1% per annum
3% per annum
~—~ 5% per annum
7% per annum
-
1
-
40 60 80 100
0 20
YEARS AFTE R P R ESENT
FIGURE 1.1 Projected cadmium concentrations in Lake Michigan for various rates of
increase in the annual input rate. The lower horizontal dashed line represents the con-
centration at which toxic effects have been reported for aquatic organisms (Marshall and
Mellinger 1980). The upper dashed line is the current U.S. EPA standard for waters of
Lake Michigan's hardness. The present rate of increase of the input rate for Lake Michi-
gan is 4.6 percent per annum, which would cause the lake to reach the toxicity threshold
for aquatic organisms in about 40 years. The authors indicate that a high proportion of
the input of cadmium is from the atmosphere. Cadmium in sediment at 10 6 gig is equal
to 1.5 X 10 ~ g/1 in water. SOURCE: After Muhlbaier and Tisue (1981). Copyright (3
1981 by D. Reidel Publishing Co., Dordrecht, Holland.
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atmospheric pollutants. We hope, too, that the report will make
apparent the probable consequences of unregulated reliance on fossil
fuels to fulfill future energy needs.
Chapter 2 reviews the scientific discoveries that led to the
realization that the atmosphere is inseparably linked to the biosphere
and that pollution of the atmosphere--even with trace amounts of
toxicants--could have serious consequences for the latter. It is
noteworthy that although atmospheric pollution has only recently
become a widespread public concern, clearcut scientific evidence for
the effects of atmospheric pollution from fossil fuel burning and
smelting was generated during the second half of the 19th century.
Confusion has recently developed over natural emissions of
substances from the biosphere to the atmosphere. The mechanisms of
exchange of sulfur, nitrogen, reactive trace metals, and organic
substances between atmosphere and biosphere, insofar as they are
known, are reviewed in Chapter 3. In Chapter 4, we quantify the
emissions of these substances from fossil fuel burning and compare the
magnitude and form of these emissions with those from other important
anthropogenic activities as well as from natural sources.
Chapter 5 is devoted to the transport, chemical transformation,
and deposition of energy-related pollutants, with particular emphasis
on physical and chemical properties of the emissions that affect their
residence time in the atmosphere and thus the distance they are
carried.
Chapter 6 is devoted to processes affecting pollutants once they
enter the biosphere, with particular attention to similarities in
pathways, repositories, and effects of different pollutants. Examples
of synergism, antagonism, and development of resistance to pollutants
are given.
Chapter 7 represents an attempt to generalize from what is known
about important pollutants and sensitive parts of the biosphere to
develop a blueprint for predicting the consequences of continued or
accelerated pollution of the atmosphere. Again, because the
information base is incomplete, only a rough, conceptual outline has
resulted. Two of the major impediments to making more specific
conclusions or predictions are the lack of a long-term data base
sufficient to quantify small increases in toxicants and the inadequacy
of methods for detecting and predicting low-level toxic effects, at
the level of either organisms or ecosystems.
In Chapter 8, we give an up-to-date case history of acid
deposition, one example of the severe biospheric effects resulting
from anthropogenic pollution of the atmosphere that appears already to
have eliminated or substantially reduced the populations of some
organisms, including fishes, in parts of their natural ranges. Owing
to the concentrated efforts of scientists in the Northern Hemisphere,
most notably in Scandinavia during the past decade, we have a much
more complete knowledge of the causes and consequences of acid
deposition than we have for other pollutants discussed here. Yet even
for acid deposition, many mechanisms and effects are poorly known.
Throughout the above-mentioned chapters we have attempted to indicate
how widespread and complicated the atmospheric pollution problem is,
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and how intertwined the biogeochemical cycles of pollutants are with
the cycles of naturally important elements. As a consequence, second-
and third-order effects may be of great importance, but they are far
more difficult to predict than the first-order effects upon which most
attention is focused.
Though necessarily incomplete in many respects, the information
synthesized by the Committee renders a rather unfavorable picture of
the consequences of current fossil fuel burning practices. Along with
the probable large-scale effects described above, slow, nearly
undetectable increases in a multitude of extremely toxic substances
are taking place. It is the Committee's opinion, based on the
evidence we have examined, that the picture is disturbing enough to
merit prompt tightening of restrictions on atmospheric emissions from
fossil fuels and other large sources such as metal smelters and cement
manufacture. Strong measures are necessary if we are to prevent
further degradation of natural ecosystems, which together support life
on this planet.
Some pollutants, such as sulfur and nitrogen oxides, particulate
pollutants, and lead, are readily amenable to control by appropriate
engineering technologies. Others, such as mercury and CO2, are more
difficult and expensive to control by available technologies. In the
long run, only decreased reliance on fossil fuel or improved control
of a wide spectrum of pollutants can reduce the risk that our
descendants will suffer food shortages, impaired health, and a damaged
environment.
CONC LUS I ONS AND RECOMMENDAT IONS
Atmospheric pollution and its consequences deserve major
consideration when the sources and sites of energy production are
decided. However, much remains to be done if we are to assess
adequately the ecological significance of atmospheric pollutants
generated by different energy systems.
To improve and refine our ability to detect what may be
irreversible degradation in natural ecosystems, increased and improved
scientific effort is needed in two critical areas: long-term
monitoring and forecasting of future effects, and ecotoxicology.
At present, the long-term data base on emission, deposition, and
biological effects of all energy-related pollutants is insufficient.
Such information is critical to forecasting ecological effects, both
of fossil fuel combustion and of alternative energy production
systems. Natural sources of the substances and linkages to the cycles
of ecologically important chemicals must also be known, in order to
discern how natural biogeochemical processes may be stressed or
disrupted.
Likewise, our knowledge of the toxicity of pollutants requires
rapid development in four major areas: (1) identification of the
phys~co-chemical and biological properties of natural ecosystems and
organisms that are sensitive indicators of stress from pollutants; (2)
development of statistical and mathematical methods for detecting and
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quantifying ecological deviations significantly outside the normal
range in unstressed ecosystems, particularly in response to the
synergistic and antagonistic effects of several pollutants acting in
concert; (3) identification and protection of ecosystems, communities,
and species that are especially sensitive to present or projected
pollution burdens; and (4) an evaluation of how current toxicity
tests, usually done with single species, relate to stresses at the
ecosystem level.
The personnel available to undertake such studies are not
sufficient in number, nor are they trained adequately in the several
disciplines necessary for the detection of subtle increases in
pollutant stress on ecosystems over long periods. Protection of our
threatened, sensitive ecosystems requires educational programs that
are specifically designed to produce scientists with the necessary
qualifications. While this need and some appropriate topics for study
are identified and discussed in this report and elsewhere (NRC 1975,
NRC 1981, Butler 1978), educational programs and research techniques
need to be more clearly defined. In particular, current educational
programs in toxicology must be upgraded to include rigorous
statistical training and thorough grounding in ecological principles,
with emphasis on detection of long-term, whole-ecosystem effects
rather than on the current, short-term tests of individual species.
The needed curriculum should utilize the combined strengths of
programs in ecology and environmental engineering. University
programs of biology and ecology usually lack strength in applied
aspects of ecology, while programs in environmental engineering often
pay insufficient attention to the foundations of their discipline in
ecology. While combined programs do exist at some institutions, many
lack the scientific rigor necessary for training experts to attack the
complex problems that will be faced in the coming years.
Current institutional arrangements are not designed to undertake
effectively the complex, long-term studies envisaged. One possibility
that deserves consideration is to set up a National Center for Ecology
and Environmental Science, with functions similar in part to those of
the National Center for Atmospheric Research and the U.S. Geological
Survey. These organizations provide alternative models of
governance--the first being supported by federal funds but governed by
a consortium of universities, the second, a larger organization both
funded and controlled federally. Such an institution would also
require the cooperation and coordination of federal agencies, such as
the U.S. Departments of Agriculture, Energy, the Interior, Health and
Human Services, and the Environmental Protection Agency.
Representative terms from entire chapter:
atmospheric pollution
