Heavy Metals in the Environment: Using Wetlands for Their Removal - Chapter 2 doc

CHAPTER 2 Problems and Needs CONTENTS Environmental Health for Humanity...21 Ecotoxicology ...22 Heavy Metals in Environment ...23 Organization of Heavy Metal Cycles...24 Evaluation of A

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CHAPTER 2 Problems and Needs

CONTENTS

Environmental Health for Humanity 21

Ecotoxicology 22

Heavy Metals in Environment 23

Organization of Heavy Metal Cycles 24

Evaluation of Alternatives 25

Toxicity 25

Initiatives in Industrial Ecology 26

Originally, before human civilization, the cycle of heavy metals in the geobiosphere was compatible with the living cover of the earth, aided in large measure by ﬁltering ecosystems, especially wetlands Most of the metals were in deposits in geological strata, rarely interacting at high concentrations with life Accelerating over several centuries, the heavy metal storage reserves

in the geological strata were brought into industrial manufacture, with uses changing rapidly as technologies changed What was most economical at ﬁrst was to mine, to use, and to discard, letting

of resource exploitation?

ENVIRONMENTAL HEALTH FOR HUMANITY

for society with heavy metals out of place The environmental lead burden is not smoothly distrib-uted spatially, and the reduction in atmospheric lead pollution from leaded gasoline means that background levels will not grow as rapidly as before, focusing attention on more concentrated sources Most studies of the physiological and economic costs of lead poisoning have involved cases of acute lead poisoning at high exposure levels, and more recently they have examined the effects of exposure to elevated levels of lead in urban environments, but not at lower levels in the general environment It is estimated that the average burden of lead in the human body is now at least 300 times that of pre-industrial human populations (National Research Council, 1993) The effect of this on overall human health is not known precisely, although there is no known lower threshold for deleterious effects of lead

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22 HEAVY METALS IN THE ENVIRONMENT: USING WETLANDS FOR THEIR REMOVAL

While lead has long been known as a toxin, the last 20 years has conﬁrmed the poisonous effects of lead for the neurological system, even at very low levels (Needleman et al., 1979, 1990)

considered cause for intervention by public agencies such as the Centers for Disease Control (CDC) and Environmental Protection Agency (EPA) (National Research Council, 1993) Low-level lead exposure has been linked to lowered intelligence, diminished cognitive function, and delinquent behavior in children (Schwartz, 1994a; Jacobs, 1996b; Needleman et al., 1996) The sources of lead exposure have changed in recent years, with the decline of leaded gasoline and lead solder in food cans, but the largest remaining sources are especially risky for children — lead-based paint and lead-polluted soil (Jacobs, 1996b)

Lead pollution from leaded gasoline and food cans was much more easily addressed by environmental regulations than the residual stock of lead in house paint and soil Manufacturers

of leaded gasoline and tainted foodstuffs could be identiﬁed and regulations readily enforced Although the use of lead-based paint in houses declined from 1940 onward (National Research Council, 1993), the danger remains as old paint ﬂakes, crumbles, turns to dust, or is disturbed

by renovation

The U.S Department of Housing and Urban Development (HUD) estimated the cost of com-pletely removing lead-based paint from the nation’s housing stock to be about $500 billion (HUD,

1990, cited in Jacobs, 1996a) (By comparison, EPA estimated the annual cost of removing lead from gasoline to be only about $500 million.) That cost is misleading, however, since interim control methods (to reduce exposure but not to remove all lead-based paint) would be much less expensive Given the toxic effects of low-level lead exposure discussed above, there are clear economic beneﬁts to such an enterprise Schwartz (1994b) estimated a social beneﬁt of $1.7 billion

economics Measuring the social beneﬁt of reducing lead exposure using emergy has not been undertaken, but would be expected to be at least as dramatic

ECOTOXICOLOGY

There is ﬁnally a general realization that humanity can be healthy only when its environment

is also healthy Understanding heavy metal toxicology also requires an understanding of these elements and their impact on the environment — the ﬁeld of ecotoxicology Some of the questions about heavy metals and environment are scientiﬁc issues about the way systems self-organize their cycles of toxic material use

Hierar-chical Approach (Newman and Jagoe, 1996) Starting with the very small scale of cells and molecular biology, chapters considered the processing of toxic substances by organisms and their behavior, populations, communities, ecosystems, lakes, and the earth as a whole Newman, in his introduction, defines the field as: “knowledge about the fate and effects of toxicants in ecosystems based on explanatory principles.” But mechanisms at a small scale of time and space (example: chemical reactions) cannot by themselves explain distributions at much larger scales Principles were not included for relating separate chapters on phenomena of different scale A discipline is sometimes defined as understanding phenomena of a particular scale (example: chemistry concerned with molecules and their processes), but it is unlikely that principles of one scale can suffice

In Chapter 4 of this book we try to relate phenomena of different scales using energy hierarchy concepts Emergy (spelled with an “m”) is a quantitative measure of the work accumulated in concentrating valuable substances from one scale to another Units and processes are given their hierarchical position by their unit emergy, which increases with scale and concentration and correlates with toxicity (Genoni and Montague, 1991) Systems models are required which combine

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PROBLEMS AND NEEDS 23

what is important among the scales of interest In this book a systems model of lead in a wetland

Much science in this century has approached each phenomenon of interest by studying

the chapters discuss various mechanisms of toxic interaction at the smaller scales of stressed organisms This is the traditional approach of trying to understand all the component mechanisms even though the larger-scale parts of the system and ﬂow in the biogeochemical cycles are con-trolling the rates If the questions and needs are environmental, is it really necessary to understand the DNA damage, molecular biology, membrane physiology, histology, organism behavior, popu-lation demography, ecosystem oscilpopu-lations, biogeography, and community composition (the topics

of the ecotoxicology book)? It is probably not practical to put that much detail from the parts in

a model intended to explain the environmental role of heavy metals

Minimodels are simpliﬁcations in the form of diagrams and mathematical equations relating the various parts and processes of a system For example, Beyers and Odum (1993) simulated the role of a toxic metal that recirculates through the photosynthesis and respiration of an ecosystem, with a generalized minimodel named TOXICPR Another model of a cycle of toxic substance (named TOXICOSM) simulated the stress on biodiversity These are top-down models, highly aggregated to show only the most important components and processes How useful are minimodels

of this class in explaining heavy metal distribution in real cases?

Ecological microcosms are containers with living, miniaturized ecosystems (examples: aquaria and terraria) Perez et al (1977) and Perez (1995) studied similar treatments in microcosms of three different sizes and found that the impacts were dependent on the size of the microcosm Large-scale impact oscillations were excluded from the small scale Questions were raised about using small microcosms to judge toxicity impact of large environmental systems Beyers and Odum (1994) reviewed some of the extensive literature that used ecological microcosms to study cycles and toxicities In this review we suggested transferring conclusions from small-scale microcosms

to larger-scale systems by multiplying the dimensions of the observed phenomena’s time, space, and unit emergy by the scaling factor relating microcosm to the full-scale system Underlying this theory is the general systems idea that processes of all scales are similar because of the energy principles guiding self-organization

HEAVY METALS IN ENVIRONMENT

Other questions concern the way the lead cycle is changing in its relationship to society What

do we need to know to set public policy on heavy metals?

1 How can human society reorganize the toxic impacts of heavy metals? People can avoid concentrations of the heavy metals such as those in acid drainages and hot-spring waters around volcanoes The principal toxic exposures now are leftovers from unwise uses of heavy metals in close proximity to people The lead use in pipes started in Roman times The tetraethyl lead that was an “antiknock” gasoline additive spread lead with motor vehicle exhausts on all the roadsides With passage of the Clean Air Act of 1972, lead emissions from automobiles began to decrease in the U.S., and the lead concentrations in transportation decreased dramatically (Eisenreich et al., 1986) The action needed to stop uses that are not compatible with life and human society is well under way

2 Can heavy metal accumulations be made safe from human interaction including the natural ore deposits and industrial waste sites? Currently there are toxic distributions and accumulations from the rush to use heavy metals in the past These include mines left open to the surface waters and aquatic ecosystems They include Superfund sites like the Sapp Swamp in this study Digging

up the metal residues and soils and putting them in a dump somewhere else is not a solution Getting the biogeochemical cycle on a track to become part of the geological cycle of slow and

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more isolated processes is the appropriate course of action Processing Superfund wastes through regular technological metal reprocessing was recommended by Staley (1996)

3 When can we increase the fraction of heavy metals supplied from reuse? Well under way are the collection and return of heavy metals for reprocessing and resupply This saves the earth reserves

requires lead, nickel, and cadmium batteries to be recycled for reprocessing, not cast into general solid waste disposal systems

4 Can the rate of use be balanced with a sustainable rate of supply? Although recycling for reuse was substantial in 1997, the rate of use of ores of lead and other heavy metals was not sustainable As the more concentrated ores become increasingly scarce, prices will rise, and more and more of the metals will have to come from recycle and reuse at greater cost Then the former great economic stimulus of cheap abundant raw materials will be over Decreasing availability of cheap critical materials and the rising costs of fuels will contribute to the leveling and decline of the global economy

5 Can society eliminate the dangerous concentrations of heavy metals left over from earlier ill-advised uses? For example, lead-based paint, crumbling into dust from old houses, is dan-gerous if ingested, especially by children playing on the ground or on the ﬂoors Lead paints have been banned from use in houses since 1978, and laws now require checks and information

to be supplied in real estate transactions Public health recommendations call for checking for lead in children

ORGANIZATION OF HEAVY METAL CYCLES

6 Is there an energetic principle of chemical self-organization that accounts for the natural distribution of the heavy metals? The tendency for heavy metals to circulate and become concen-trated high in the energy hierarchy of the earth and of the economy is related to energy and emergy

ore bodies, the result of converging processes of the energy hierarchy of the global system According to this concept, position in the energy hierarchy determines real wealth value, and justiﬁes costs in processing and the kind of reuse or recycle that is appropriate

7 How does the precivilization cycle of heavy metals compare with the present cycle? Appar-ently, the earlier system kept lead and other heavy metals bound in cycles of the land, keeping levels in the atmosphere, lakes, and oceans low Is global toxicity ultimately due to letting heavy metals get into atmospheric and aquatic circulation?

8 How can the use and processing of heavy metals by the economy make use of the natural principles guiding scarce elements? Public policies on mining and scarce minerals now are largely

a better basis for evaluating and planning society’s use of scarce metals in the long range Alter-natives are recommended that maximize the production and use of real wealth

9 What incentives help consumers recycle and reuse heavy metals? Already, deposits are being required to facilitate returns for recycling, as in war times and earlier times of less afﬂuence Tax exemptions can be offered to the public based on emdollar values of recycle and reuse The high value to the public of keeping the metals in appropriate reuse and out of the air and water cycles justiﬁes public subsidy Emergy-emdollar evaluations indicate how much is appropriate

Incentives can also be used to help the natural processes regulate the environmental recycling Conservation and special-use easements can be purchased where lands and waters need to be managed for the public interest and safety For example, a public easement can be purchased so that a wetland containing heavy metals is not excavated Special restriction easements are less expensive than outright land purchase; they allow private interests to use lands and waters for compatible purposes

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EVALUATION OF ALTERNATIVES

10 Can the real-wealth value (emergy) of heavy metals be given an equivalent economic basis? Emdollars are the dollars of the gross economic product made possible by an emergy contribution

11 Can we deﬁne what is the appropriate best use for scarce chemical elements? For any need,

a desirable policy selects alternatives that achieve objectives with the least use of the most valuable materials Here the emergy value measures of the accumulated work of nature and humans are better than the market values for measuring which resources are most valuable and scarce, to be used sparingly See Chapter 4

12 How does the worth of scarce metals compare to strategic needs and safety of nations? On what basis can policies be deﬁned for conservation? Resources essential to military prowess and security were stockpiled during World War II, but used to accelerate the economy after the war Both practices need to be put on a comparative basis Economic use and defense contributions can both be evaluated on an emergy-emdollar basis, thus representing the real-wealth value to the public Emdollar values of heavy metals are much higher than market values A student report by Pat Dalton in 1986 found emdollars of defense about twice the economic value, partly because of the high transformities of strategic metals

13 Can we evaluate the present and potential role of wetlands and other natural ﬁlters in environmental self-regulation? The discovery that many wetlands capture and denature toxic sub-stances raises the possibility that safety for human society can be achieved with little cost by letting

14 How can the useful properties of peat for maintaining a healthy biosphere be evaluated when economic profit evaluations appear to justify destructive uses? Lynne (1984) had difficulty finding any method of economic analysis that would prevent the nonrenewable use of Florida peats for agriculture Odum (1996) found the Santa Fe Swamp in North Florida was worth 1.6 billion emdollars to the public, much more than if the peat were sold at market price This evaluation used emergy procedures, which are based on the work contributed by nature See Chapter 4

TOXICITY

15 Can measurement of heavy metals in the pore waters of sediments represent the tendency for metals to be toxic to organisms or to be released to open waters? Pore water analysis is a recent approach to determining the hazard of sediments containing heavy metals (Campbell and Tessier, 1996) For example, they report an experiment by Ankley et al (1991) that correlated mortality of benthic amphipods to the ratio of heavy metal to AVS (acid volatile sulfides) The idea is that more metal relative to potentially binding sulfide means more metal free to affect the animals Yet there are many binding mechanisms in sediments and wetlands (particle adsorption, base exchange, complexing with humic acids, precipitation) Are binding mechanisms complementary so that there are usually backup mechanisms to bind heavy metals not bound by the first process?

16 How should acute toxicity tests (mortality in a short time — <96 h) and chronic toxicity tests (mortality over a long period — >96 h) be used to manage lead in the environment? Whereas acute tests can quickly determine dangerous levels, should they ever be used for Environmental Quality standards (EQ)? The time scale of human lives is much longer, and the time for accumulating impact is greater than for short-lived test animals Being on a larger scale, humans are more sensitive

to some stresses, such as ionizing radiations, than other species of plants, animals, and microbes

17 Can emergy per unit mass and/or transformity (the emergy per unit energy) be used to predict toxicity of substances? Energy hierarchy theory ﬁnds the effect of something increasing

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is an evidence of more embodied work (and thus higher emergy per unit) An old pharmacological principle states that drugs that are most beneﬁcial are also the most toxic at the wrong dose In a sense, environmental pollution is a state of materials in the environment in the wrong dose Does greater potential impact (for good or harm) occur when transformity of substance and interacting receiver differ by one or two orders of magnitude? The smaller impact of toxic substances on small microcosms compared to large ones may be an example

18 Can present concepts of heavy metal risk be put on a simpler and more general basis using emergy? The complex concepts of risk now in use to judge heavy metals in the environment evaluate

“probabilities” of metal concentration, probabilities of sensitive organisms being present, and probabilities of the interests of society being impacted (Suter, 1993) Perhaps emergy and emdollars can evaluate a potential impact and thus rank priorities and reorganize the use systems to convert impacts into beneﬁts

19 What index of overall ecosystem condition is the best indicator of stress due to heavy metals?

Indices of diversity of plants and animals have been consistent in indicating pollution See, for

of ecological integrity Many papers ﬁnd lower species diversity with increasing heavy metals There is toxic action, but also an effect of helping those species that are adapted to the heavy metals

in Silver Springs, FL, rather than the high diversity periphyton growing on glass slides See

INITIATIVES IN INDUSTRIAL ECOLOGY

Industrial ecology is a recently popular word for initiatives from private industry to develop a stable and efﬁcient system of material use and recycle Socolow et al (1994) say the goal of industrial ecology is “evolution of the world’s industrial activity into suitable and environmentally benign systems.”

20 Can industries such as battery makers take over the whole cycle of processing, use, reuse, and control of environmental recycle? In our time many people seek to privatize many public needs Can the private industries that now produce heavy metal products take over the whole cycle of a heavy metal including recycle, reuse, and safe control of environmental releases? The products are

at the high value end of the cycle, and incentives are provided by market prices and demand for use Recycled remnants and wastes are at the more dispersed part of the cycle where there is little market demand or source of money To manage privatizing for the public good may require emergy-based economic subsidies or tax incentives for the dilute part of cycles

21 How will changes in automobile transportation affect heavy metal use and environmental impact? Urban growth in the 1990s meant more cars, more air pollution, and more consideration

of alternatives to the heavy lead batteries The Paul Scherrer Institute (1998) compared the electrical energy per unit mass (watt hours per kilogram) from new, lighter-weight batteries Older lead batteries delivered about 35, nickel–cadmium batteries 55, nickel–hydride 76, and zinc–air batteries

100 A net emergy evaluation (which includes changed monetary costs) is needed to see if the lighter batteries can be a net beneﬁt With an industrial ecology perspective Graedel and Allenby (1998) document the central role of automobiles in our civilization They found the lead batteries still with the least cost ($70 to 100 /kWh) A switch in metals would change the kind of heavy metals impacting the environment, but those most considered are all ﬁltered by wetlands Will electric cars increase heavy metal risks and costs? Is this transportation sustainable? A Carnegie-Mellon University study by Lave et al (1995) on “environmental implications of electric cars” stated that electric car mandates like one proposed in California may expose thousands of

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people to toxic doses of lead while unnecessarily accelerating the demise of an important non-renewable resource (Berriman, 1995) Lead released with an electric car system was stated to be

741–742.) Previous evaluations of electric cars indicated they were not a net beneﬁt and thus not likely to prevail (McGrane, 1993)

22 What is the pattern of heavy metal use and processing appropriate and economical for a time of less fuel availability and contracting economy? For the future, what is the long-range scenario for use of metals? Will there be a climax accumulation of people and machines on the earth, followed by decreases as the fuel energy basis for the high concentrations decreases? What

When the shortages of nonrenewable resources force the global economy to a lower level, will the uses of heavy metals be less? Will there be more conservation and reuse, with diminishing environmental toxicities? An evaluation of global fuel reserves by Campbell (1997) estimates fuel prices generally rising after the year 2009

Initiated by Georgescu-Roegen (1977) is the idea that civilization could become limited more

by the critical materials, such as heavy metals, than by the fuels However, ecosystems concentrate critical materials several orders of magnitude as needed so long as they have their energy budget

In our society more and more fuel energy is being used to recycle, reconcentrate, and reuse the heavy metals as the concentrations available for mining diminish Emergy evaluation allows energy reserves and reserves of critical materials to be compared on an equivalent basis Both types of nonrenewable resources are supporting the ultimate pulse of this civilization now under way With the questions of this chapter in mind, consider next some of the published literature on

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