Neutralization of acidic waters E3y Howard A. Simonin
Agricultural limestone and other alkaline materials have long been used to reduce the acidity of soils and to improve agricultural productivity. More recently the application of neutralizing materials to acidic waters has become a proven means to produce a habitat suitable for fish and other aquatic life. Lake neutralization (more commonly referred to as lake liming) also has been used to protect certain waters with low acid neutralizing capacity from increasing acidification. In this article, I will review the positive and the negative aspects of liming and its practical application to the problem of acidic deposition. One primary concern is that liming does not mitigate many of the problems that result from acidic deposition. Although lake neutralization is a useful practice, it is not presented as a solution to the acid rain problem. Liming is a means of restoring or protecting a few systems affected by acidic deposition while legislators pass a fair and equitable program to control the source of the problem-excessive emissions of sulfur dioxide and nitrogen oxides. Lake liming has been shown by numerous researchers to be a valuable and important fisheries management tool for use in certain acidified waters ( I 4). The primary benefit of a lake neutralization project is the improvement of the water quality to the point where a viable recreational fishery can be established and maintained. Liming also may be conducted to protect special habitats or strains of fish (e.g., genetically unique strains of brook trout that are threatened by acidification). Successful reproduction and recruitment of fish populations also can occur shortly after treatment (2), and the diversity of fish and other organisms present in the ecosystems often increase as a result of the treatment. Trout or other fish species may be stocked in a lake that was previously too acidic for fish survival. Fish populations have been lost in many waters as a result of acidic deposition; a number of these lakes can be neutralized and a viable recreational fishery restored. Other animals and plants that were eliminated as the ecosystem acidified W13936W8810922-11431601.5010
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populations of these organisms may decline. Similarly, when fish are stocked in a formerly fishless lake, certain organisms are preyed on by the fish and are adversely affected. A negative impact also may be caused by the liming activity itself, particularly if the lake is located in a wilderness or protected forest area. Although this impact often can be reduced by altering the neutralization method or timing of the treatment, liming may constitute an unacceptable intrusion into a protected wilderness.
may become reestablished after liming, and the result may be a more diverse aquatic community. The benefits to the ecosystem from lake neutralization may therefore include improved habitat for crayfish, mayflies, minnows, and other organisms sensitive to acidification; more abundant food resources for loons, osprey, eagles, mink, and oner; increased rate of decomposition and cycling of nutrients in the aquatic system; and decreased levels of toxic aluminum, which although still present in the watershed, becomes bound in the lake sediments. Many chemical materials have been used for lake neutralization. Hydrated lime, soda ash, quicklime, and others have been utilized, but agricultural limestone is the material most widely used. Agricultural limestone is relatively inexpensive, noncaustic, and intermediately soluble in water ( 5 ) . Thousands of lake neutralization projects have been conducted in Sweden using many different methods of application. In the United States, application methods have ranged from expensive helicopter-dispensed slurry systems to labor-intensive manual spreading of lime by boat or snowmobile. Although no major detrimental environmental impacts appear to result from neutralizing and maintaining the water quality of selected lakes with agricultural limestone, some adverse effects are possible. Certain plants and animals can tolerate an acidic environment; when the lake is neutralized, the
1988 American Chemical Society
Liming, a management decision Periodic reliming of waters in a liming program is an important management consideraiton. Until acidic deposition is reduced, the limed waters will reacidify and therefore will require careful monitoring to maintain water quality favorable to fish populations. Once a lake is limed and a fishery reestablished it is imperative that the lake not be allowed to reacidify, In addition to the problems caused by low pH, reacidification could cause a release of toxic aluminum from the sediments, most likely resulting in fish mortalities. Reliming therefore needs to be scheduled when the water chemistry falls to a certain nontoxic threshold level. The frequency of reliming is dependent on the hydrologic flushing rate of the lake. The use of rigorous site selection criteria can assure that the adverse effects of liming are minimized and the effectiveness of treatments maximized. Lakes that can maintain neutralized water and provide a viable fishery are considered good candidates. Waters with high flushing rates would not be expected to maintain suitable water quality for long. In the Adirondacks of New York state, limed lakes with flushing rates higher than 3 timedyear reacidified within a year after treatment (4). In its Acid Precipitation Mitigation Project, the U S . Fish and Wildlife Service concluded that lakes that flush more frequently than twice annually are not efficiently treated by direct water COIL umn liming (6).This flushing-rate criterion appears to be the most important factor in selecting good lake candidates for liming projects. Certain acidic waters would not proEnviron. Sci. Technol.. Vol. 22. No. 10. 1988 1143
vide a good fish habitat even after liming. These waters, including those with naturally low dissolved-oxygen levels or unsuitable summer water temperatures, should not be considered for lake neutralization projects. Similarly, naturally acidic bog ponds should not be limed because it is important to maintain and preserve these unique ecosystems. Other factors also need to be considered in selecting the best possible candidates for liming projects. Because the primary objective of most liming projects is to restore an acidifed pond or lake to a viable recreational fishery, the water should be relatively accessible for use by fishermen. Accessibility is also important in reducing the actual costs of neutralization, water quality monitoring, and fish stocking. Lake neutralization should include a commitment to long-term management of that water, and the availability of funds and staff to monitor and relime the water is an important consideration. These criteria all need to be used in the lake selection process before a neutralization project is actually started.
Limitations to liming Lake liming does have definite limitations; even if all suitable candidate waters were limed, many acidified lakes would remain. Recent survey data for the Adirondacks indicate that about 75% of the acidic lakes have flushing rates greater than 2 timeslyear (7, and would therefore be unsuitable for direct water column liming projects. Other methods for treating these lakes have been suggested but have not been proven to be effective, practical, or environmentally sound. These methods include watershed liming and the continous addition of lime to tributary streams to provide longer lasting water quality neutralization. Lake liming does not protect the ecosystem from acidic episodes that occur during the spring snowmelt and during large precipitation events. During these times large volumes of acidic water may enter the lake and create a toxic environment in the zone where the runoff water mixes with the lakewater. Organisms that are not able to move out of these toxic zones may be adversely affected. Many miles of streams and rivers have been negatively affected by acidic deposition, and lake liming does little to restore these ecosystems. In certain cases stream liming, which has been conducted in Scandinavia (2) and several parts of the United States (6, s), can effectively neutralize stream acidity. The problems with liming in many affected streams are both logistical and technological. Logistically, many streams are not accessible by road and 1144 Enviran. Sci. Technot., Val. 22. No. 10, 1988
cannot be easily supplied with large amounts of lime. Constructing large lime dosing structures would not be permitted in many wilderness areas where affected streams are located. Technologically, stream-dosing devices have not been demonstrated to operate effectively during spring snowmelt, when many streams flood their banks, form ice dams, and create difficult stream-gaging situations. It is during spring snowmelt that the most acidic conditions occur and the most lime would be required. Other problems of acidic deposition that are not mitigated by neutralizing acidic lakes include impacts on air quality, trees, and structures. As is discussed above, liming a handful of acidic lakes is not a practical solution for the countless acidic streams or acid lakes with high flushing rates. Acidic deposition continues to add acidity to sensitive ecosystems and reacidifies
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limed waters. When deposition levels are reduced, however, the water quality of acidified lakes is predicted to improve substantially and in some cases rapidly (9). The liming of acid waters is a viable and important fisheries management tool in certain selected waters, but it is not a realistic alternative to an effective program of emissions controls. Several time factors are important in discussing liming and the impending passage of acid deposition control legislation. Time will first be needed to devise control strategies, and the emitters of acid rain precursors will be allowed several years to implement reductions. After these emissions and resulting acidic deposition are reduced, the affected resources will require a number of years to respond. In the interim, lake neutralization will continue to be an important tool for managing certain acidic waters
References ( I ) Flick. W. A,; Schofield. C. L.; Websler. D. A. In Acid RainIFisherim: Johnson. R. E., Ed.;American Fisheries Society: Bethesda. MD, 1982; pp. 287-306. (2) Hasselrot. C. L.; Hullberg, H. Fisheries 1984, 9(1), 4-9. (3) Schofield. C. L.: Gloss, S.P;Josephson. D. “Extensive Evaluation of Lake Liming, Resloeking Strategies, and Fish Popdation Res onse in Acidic Lakes Following NcutraEzation by Liming”: Interim Progress Rcport NEC-86/18: U S . Fish and Wildlife Service, Eastern Energy and Land Use Team: Washington, DC. 1986. (4) Gloss, S . P: Schofield. C . L.; Sherman. R. E. “An Evaluation of New York State Lake Liming Data and the Application of
By Ellen Silbergeld
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(6) (6) (7)
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Models from Scandinavian Lakes to Adirondack Lakes:” U.S. Fish and Wildlife Service, Eastern Energy and Land Use Team. Washington, DC, in press. Fraser. I. E.; Britt. D. L. “Liming of Acidified Waters: A Review of Methods and Effects on Aquatic Ecosystems”: Report 80/40.13; U.S. Fish and Wildlife Scrvice. Eastern Energy and Land Use Team, Washineton. Team. Washington. DC. DC, 1982. Schrieber. R. k K.;;Britt, D. L. Fisheries 1987. /2(3), 2-6. Adirondack Lakes Survey Cor ration. Vols. 1-15. $w York 1984-86 R~DOCIS. State Deparimeni of Environmental Conservation: Ray Brook. NY. Zurbuch. P E. Fisheries 1984, 9 0 ) . 4247.
(9) Gherini. S. A. et al. In n e Inregrated Loke-Watershed Acidificarion Srudy: Goldstein, R . A , ; Gherini. S. A,. Eds.; Electric Power Research Institute: Palo Alto. CA, 1984; Val. 4, pp. 7.1-7.47.
Howard A . Simonin is a senior aquatic biologist with the New York Department of Environmental Conservation. He has conducted research on the effect of acidic deposition and recently has evaluated New York i program of liming selected acidged waters. He is located at the Rome Field Station in Rome, NY
Science and the EPA: Voodoo toxicology
During the past eight years, EPA has had a mixed relationship with the scientific community. Its use of science has ranged from attempts to integrate stateof-the-art basic science into policy to proposals so inexplicable that they are charitably characterized as voodoo toxicology. During the first four years of the Reagan administration, actions were taken to deliberately purge EPA of its science base, and eminent members of the scientific-technical establishment outside the government were proscribed from appointment to agency advisory committees. More recently, EPA is relying increasingly on science to validate policy, particularly now that risk assessment has taken more precedence as a basis for policy and regulation. Through this process, however, remarkably inconsistent signals are being sent. For example, a series of highly controversial issue-specific decisions, such as the recent cancer risk management decisions on dioxin and arsenic, are being set in the context of explicit guidelines defining scientific ground rules that frequently contradict the content of the decisions themselves. Science has rescued EPA-and the country-from some of its worst attempts at “reform.” When, in 1982, Anne Burford accommodated George Bush3 Regulatory Reform Committee’s high priority identification of lead as a target for deregulation, the biomedical community fought against the idiocy of once again adding lead to gasoline. In less dramatic cases, scientists on National Research Council boards and committees have provided guidance that prevented EPA from adopting weakening policies on drinking water and other issues. More critically, there
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has been a forum for consensus development through the NRC that will outlive EPAs current inaction on radon and acid rain. The record of these outside scientific advisory committees is a strong endorsement for extending requirements for EPA to consult with the NRC on issues beyond air and water. Environmentalists are more than willing to trust this consultative process. It has been my experience that the deliberations of peer review have not caused undue delays in regulatory action, which are often rightly decried by Congress and my colleagues. However, the country cannot rely entirely on outside scientists to rescue EPA from its more egregious folly. Methods must be developed within the agency to internalize a primary allegiance to good science, to principles of health promotion and disease prevention, and above all to effective communication between EPA and the outside scientific world. Appointments of
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persons to the agency with scientific stature-like Bernard Goldstein and John Moore-are welcome signals of solidarity. But one of the greatest threats is EPA’s appalling mismanagement of intramural and extramural research. The Science Advisory Board of the agency has repeatedly criticized EPA’s lack of long-term research goals and the routine plundering of the Office of Research and Development resources by program offices. Extramural research is equally mismanaged: Many academic scientists have learned to distrust EPAs allegiance to the peer review process. Currently EPA is trying to gain s u p port for a new venture in long-term research-a novel quasi-governmental research institute. At the same time, however, the agency continues to work against allocation of Superfund monies to the National Institutes of Health for basic research on toxicology and environmental engineering. It is not clear that EPA truly accepts the integral role of research in improving decision making. Until these issues are resolved, and until EPA constrains its proposals from the voodoo of the dioxin “reassessment” series, it is hard for scientists to trust an institution with a record as unpredictable as EPA’s in supporting science and accepting its conclusions.
Ellen Silbergeld is a senior scientist with the Environmental Defense Fund. She received her Ph.D. in environmental engineering from Johns Hopkins Universiiy and sat for the past jive years on EPA’s Science Advisory Committee and has served on several committees of the National Research Council. Environ. Sci. Technoi., Vol. 22. No. 10, 1988 1145
