INNOVATIVE AREAS OF RESEARCH
ORIGIN AND MODIFICATION OF CONTAMINANTS
(1) Reductive Dehalogenation of Chlorinated Organic Contaminants (Boyd).
A major research emphasis over the past five years has been the microbial degradation of organic toxicants in soils, sediments and groundwaters. Reductive dehalogenation is a degradative reaction which occurs in certain anaerobic environments. In this process, chlorine is removed from organochlorine toxicants and is replaced with hydrogen. The dechlorinated compounds are potentially less toxic, less likely to bioaccumulate, and more susceptible to further microbial degradation. Many compounds which are resistant to aerobic degradation are subject to reductive dehalogenation reactions. Fellows can study the reductive dehalogenation of a variety of environmentally important compounds including PCBs, pentachlorophenol, perchloroethylene and several pesticides. Efforts are currently underway to establish the importance of reductive dehalogenation in contaminated sediments and groundwaters and to overcome factors limiting dechlorination. This transformation can be used to remediate contaminated soils so important research projects can be devised in this area. A further goal is to produce microbially dechlorinated products, e.g., dechlorianted PCBs, and evaluate directly the resultant toxicity reduction. This allows for risk based clean-up criteria rather than the conventional concentration based approach.
(2) Attenuating Organic Contaminant Migration by Soil Modification (Boyd).
A major research objective has been to devise methods to prevent the migration of organic toxicants through soils, aquifers, and clay containment barriers. The Fellows may elect to study modifications of soils and bentonite by placing hydrophobic organic cations on their exchange sites via cation exchange reactions. Organic cations of the form [CH3)3NR]+ have been used to displace naturally occurring exchange ions, resulting in significantly enhanced sorption and greatly reduced transport of otherwise mobile organic groundwater contaminants. Subsurface sorbant zones may be formed by in situ injections of cationic surfactants and, if properly placed, these zones may intercept and immobilize contaminant plumes. Coupling enhanced contaminant immobilization via soil modification with biodegradation is being developed as a comprehensive soil restoration technology. Modified clays are also being developed to enhance the containment capabilities of clay landfill liners and bentonite slurry walls. This research has many important fundamental and applied research aspects.
(3) Bioavailability of soil-sorbed contaminants (Boyd).
In order to successfully implement bioremediation technologies, the target contaminants must be accessible to pollutant degrading microorganisms. The influence of sorption/desorption processes on the bioavailability of organic contaminants and pesticides in soils and subsoils is poorly understood despite its potential to limit the rate and extent of pollutant degradation. Fellows may choose to examine this question at a fundamental level by addressing the question of whether soil or sediment-bound contaminants are available for biodegradation, or if desorption into the aqueous phase is a prerequisite for biodegradation. If the latter is true, then the kinetics of desorption, if sufficiently slow, may limit the overall rate of degradation. Thus a related area of research is quantifying sorption/desorption kinetics of contaminants in soil and understanding factors that influence these kinetics, such as contaminant structure, contaminant aging, and water solubility. A more practical question is what can be done to overcome limited bioavailability. One approach under study is to use surfactants to raise the apparent solubility of contaminants and to increase their bioavailability.
(4) Microbial Mitigation of Soil Contaminants (Tiedje).
Soil microorganisms are vital mitigators of agricultural disturbances to soil and water by decomposing pesticides, cycling extra nutrients, and oxidizing extra organic matter. Sometimes microbes appear to fail to return the agricultural soil-water ecosystem to its desired state. One of the reasons is the lack of understanding about the distribution of microorganisms with more specialized features. It has always been assumed that a microbial process found in one soil will be in all soils. This is true for common processes such as cellulose decomposition, denitrification, and decomposition of less complex pesticides, but it does not appear to be true for chemicals in which the frequency of degraders is low and may not be true for "ecotypes" that carry out the common process, e.g. pesticide degraders that are more effective at part-per-billion concentrations or nitrogen cycle organisms that are adapted to the vadose zone. Thus, the next level of understanding about microbial processes requires some knowledge of the populations behind those processes to know how uniform they are and whether they have features unique to particular conditions.
Our research has focused on developing methods for community level analysis of microbes using a suite of molecular, chemical, physiological and imaging approaches. Some of these are ready to be applied to different problem domains. Two projects are offered that would draw on these methods to answer the above questions.
Innovative Research Training Area 1. Are microorganisms metabolizing selected chemicals in the surface soil the same as those in the vadose zone? In a similar non-agricultural soil? This would help answer the question of whether degrading organisms are uniformly distributed and, therefore, their kinetic and regulatory features (e.g. induction) can be modeled with the same parameters. But, it may be that the organisms in the vadose zone are specialists for low concentrations (Vmax/Km), which would be desired for this region. Or, it might be that the patchiness of organisms in this zone is so severe that effective remediation cannot be achieved. We propose to use a suite of DNA-based methods that allow to resolve microbial differences from family to strain level, depending on the degree of distinction present. These methods include 16S-23SrDNA-PCR, REP-PCR, RFLP with conserved functional probes.
Innovative Research Training Area 2. Are the "ecotypes" of nitrogen cycle organisms selected for by agricultural management? Organisms of this class transform most of the nitrate leaving agricultural ecosystems. Our laboratory has cloned heme-nir (nitrate reductase) and Cu-nir genes from denitrifiers and they recognize over 90 percent of the denitrifiers testes to date. We also have the nos (nitrous oxide reductase) gene as a probe. Recently, we have determined and tested primers for PCR that are useful in detecting virtually all of the Cu- or heme-containing nirs, and hence have a sensitive molecular tool for assessing denitrification in soil or sediments. We are currently using these primers to develop quantitative PCR for DNA, for activity (MRNA), and for diversity (DGGE) studies. These gene probes and primers will be used against soil DNA, enrichment DNA, and numerically dominant isolate DNA to determine similarity or differences in soil denitrifying communities in response to agricultural practice. Surface, vadose, and riparian soils from an agricultural landscape will be compared to a similar, but non-agricultural landscape.
(5) Soil Processes the Control Nitrate and Phosphorus in Waters (Ellis).
To reduce leaching, agricultural systems must be developed that keep nitrate in the root zone to be assimilated so none is left at the end of the growing season. The failure of current agricultural systems to do that successfully has led to the degradation of groundwaters in the United States. Alternate management systems are needed to allow production agriculture to be compatible with maintaining adequate groundwater quality. Low input agricultural systems are being studied as part of the Long Term Ecological Research (LTER) system at Kellogg Biological Station. Through a analyses of the nitrogen dynamics in both high and low input agricultural systems, Fellows can be trained to research a number of aspects of this problem and to integrate their findings with those of the LTER team.
Phosphorus dynamics are also important to surface water quality. No-till agricultural systems have become very popular in the past five years, but they may lead to stratification wherein much higher levels of phosphorus remain in the surface of the soil. As this has not been studied, it would present an excellent research topic that would enable the Fellows to exercise initiatives in devising approaches to the problem.
(6) Pest Management/Water Quality (Bird).
Optimal use of pesticides in agriculture is a procedure designed to optimize productivity without increasing environmental and human health risks. During the past 25 years, MSU had a pioneering role in the development of integrated pest management (IPM). MSU Water Science Fellows will have an opportunity to research pest management procedures designed to minimize the potential of groundwater contamination while maintaining appropriate crop productivity and quality. Fellows will be able to specialize in entomology, plant pathology, weed science, nematology or IPM. The approaches for alternate control or pesticide optimization could include research on biological control organisms, cultural procedures, genetic manipulation, or regulatory procedures for reducing groundwater risk. The potential exists for highly applied or basic research programs.
TRANSPORT OF CONTAMINANTS BY WATER
Water management and control depend on several structural factors in the ecological system. Some of these are: groundwater flow and chemical movement, surface water flow and chemical movement, and agricultural water management for crop production processes. In addition, the chemical, biological, physical, and geological phenomena in the aquatic environments and soil-water quality are influenced by agricultural and industrial processes. Therefore, quality and cost control of water use, including risk assessment and economic analyses must be employed in relation to regional innovations in institutional, cultural, and physical infrastructures that provide the market environment and support services for efficient use and maintain the quality of the water resource base. In the larger framework, national and international policies, regulations, and incentives must be devised to preserve the long-term integrity of water resources.
The ability to understand, plan, manage, and control water resources is crucial to sustain the quality and quantity of the supply. Models are available for corn, wheat, barley, soybeans, dry beans, potatoes and alfalfa. Fellows will have the opportunity to develop models that relate growth of other crops to climate, soil conditions, and fertilization practices. These models will be developed to predict the contaminants, especially nitrates, that remain in and are transported by water.
The Fellows will be trained to research natural compounds and contaminant movement through saturated organomodified soils. The limited sorptive capacity of some soils can be greatly improved by the deliberate chemical organomodification of the clay fraction of the soil. These soils have been advocated for use in permeable sorptive zones to provide engineered control of the movement of dissolved organic contaminants. Development of this innovative approach requires interdisciplinary training to develop an understanding of the physical, chemical and microbial processes that occur naturally or that may be forced. This is essential to identify standards and opportunities for enhanced remediation of groundwater contamination offered by controlling conditions in the sorptive zone.
The finite element method will be used to predict the rate and extent of the movement of dissolved chemicals through an aqueous environment. Several preliminary models now exist. They use empirical constants and characteristic soil curves to provide input parameters. These empirical relationships could be more accurately described by factoring in random variables. In order to estimate the lack of information about a given hydrologic system and the risk associated with making a decision based on the output of these models, it will be necessary to restructure the model from "constant" to random variables.
Therefore, the present Finite Element Method Surface Water Hydrology Model (FEM SWHM) and the Agricultural Nonpoint Source (AgNPS) model will be restructured with pseudorandom number generation routines to simulate the empirical data upon which these constants are based.
(10) Water Relations of Forestland and Rural Watersheds at the Landscape Level (Hart)
Human habitat depends on the quantity, quality and fluctuations in flow rate of water that occur in soils, surface waters, riparian areas and wetlands. These depend on the climate, watershed characteristics and the land management patterns occurring within the watershed area. Therefore, analysis and management of water on a regional scale is dependent on a knowledge of the interactions between climate, topography, vegetation, animals, soils, groundwater and surface drainage for interacting watersheds in the regional area. In many landscapes the watersheds must be conceptualized, analyzed and managed as systems and subsystems. Various silvicultural, agricultural, rural and urban land uses interact with the landscape factors to result in nonpoint effects on water attributes.
The Fellows training will include course, research and discussion opportunities relative to these regional landscape considerations. Research and discussion opportunities can include: 1) hydrologic, biologic and landscape ecologic relationships in watersheds; 2) quantity and quality of waters entering groundwater and wetland surface systems from natural and managed landscape situations; 3) effects of vegetation removal, conversions and management on nonpoint source inputs to water systems; 4) soil residuals, leachate and groundwater effects from additions of wastewater, sludge, herbicides and other agri-chemicals used on watersheds; and 5) integrated effects of various watershed management use alternatives on landscape water resources. Research priorities emphasize ecologic and hydrologic evaluation and classification of landscape systems; relationships between climatic inputs and local ecosystem functioning; soil and groundwater effects from velpar use for pine plantations and Christmas tree production; municipal sludge application effects on plants, animals, soils and groundwater; and geographic and integrative analysis of landscape sized areas. These research activities have established extensive cooperative relationships between university researchers and various federal, state and industrial land management agencies.
FATE OF CONTAMINANTS IN SURFACE WATERS
(11) Development of a computer model to predict the dynamics of bioaccumulation of xenobiotic chemicals in aquatic organisms (Giesy, Zabik and D’Itri).
One major question about the use of biomonitors and their bioaccumulation has been how accurate the time integrated estimation is for contaminant levels in the environment. The concentrations depend on both the species and the contaminant. Differences in kinetics for uptake and depuration may hinder generalizations. For example, the uptake of dieldrin by mosquito fish is eight time faster than that of aldrin. Also, even species with similar phylogenetic origins may respond differently to the same contaminant and accumulate it at different rates, as is the case with two species of clam. This makes correlation difficult. Therefore, biomonitors may not provide an adequate indication of time integrated concentrations of the pollutant in the environment unless they can be integrated into a computer model in some type of multivariate statistical pattern recognition technique. As with any statistical method, multivariate algorithms are based on a number of assumptions. The variables usually must be distributed as multivariate normal with common variance and covariance. This method also can be applied between classification groups. To avoid chance patterns in the data, the number of observations must be greater than the number of variables being studied. Under this training proposal, computer modeling techniques will be developed to integrate these data along with passive samplers to give as reliable, accurate, and precise data as possible to achieve dynamic and predictive modes in aquatic contamination problems.
The objectives of the research that we have been conducting has addressed the development and application of in vitro assays to determine the estrogenic potential of individual compounds and complex mixtures from hazardous waste sites. The ongoing research is part of an integrated program that is designed to reduce uncertainty in ecological and human risk assessments by developing and validating in vitro and in vivo assays to determine the total chemical activity of estrogen agonists and antagonists in the aquatic environment. We have developed several novel in vitro assay systems in fish and mammalian cells for the rapid, sensitive identification of complex mixtures of "estrogenic" or "anti-estrogenic" compounds in surface waters and fish tissues. We have also developed and are now validating solid phase extraction, fractionation and instrumental quantification techniques to determine the "estrogenic" or "anti-estrogenic" activity of complex mixtures of compounds in surface waters by use of bioassay-directed instrumental analyses. The protocol that we have developed uses instrumental analyses in a Toxicity Identification and Evaluation (TIE) approach to establish a mass balance to determine if all of the possible "estrogenic" compounds have been identified. These methods are being used in a monitoring TIE scheme that has focused on surface waters in Michigan. During the first two years of the project we have determined the "estrogenic" and "dioxin-like" potential of a number of point sources, including waste water treatment plants, industries and hazardous waste sites. Some of the most "active" responses to the bioassays have occurred at the Federal Marine Terminal site, a hazardous waste site on the Detroit River.
We are also developing and validating laboratory and field biomarkers of exposures of fishes to Aestrogenic" and Aanti-estrogenic" compounds. We will report the results of controlled laboratory studies of the responses of both fathead minnows and gold fish to several prototypical estrogenic substances. We have completed a calibration study of the effects of 17b-estradiol (E2) on the gross and histological pathology, hormone status and reproductive performance of fish. In addition to this definitive study, we have investigated the effects of several compounds that have been reported to be estrogenic and occur in surface waters near waste sites. These include nonylphenol and octylphenol and their ethoxylates. The results of two years of field monitoring of concentrations of plasma hormones in caged fathead minnows and goldfish below effluents and point sources will be reported. In addition concentrations of vitellogenin in cages fishes will be compared to responses of in vitro assays to extracts from solid phase samplers collected at the same locations. The results of these studies indicate that monitoring of vitellogenin in the plasma of male fishes is not a good predictor of reproductive performance of pairs of males and females exposed simultaneously. Furthermore, the estrogen-like effects of these compounds seem to be due to an increase in circulating hormones, not direct action as E2 agonists, such as has been proposed in the literature. We will discuss the possible mechanisms of action and implications for screening an monitoring programs.
FATE OF CONTAMINANTS IN GROUNDWATERS
(14) Development of an integrated hydrogeochemical/isotopic model for aquatic systems (Long and Ostrom).
Predicting the fate of organic and inorganic pollutants in the ecosystem and planning effective designs of landfills for municipal and hazardous wastes depend on understanding natural hydrodynamic and chemical processes and individual site variations. The Fellows' training will be designed to enable them to construct new research initiatives on the development of an integrated hydrogeochemical/isotopic model for aquatic systems. Selected training in research methods can include: (1) obtaining data from laboratory studies to describe the fate of pollutants such as adsorption-desorption reactions for organic and inorganic chemicals in ecosystems and link them to computer chemical models, (2) measuring the natural chemical and isotopic evolution of groundwaters and linking them to computer chemical and multivariate models, (3) estimating the effect of microbiological processes on groundwater systems by tracing environmental isotopes and computer chemical modeling, and (4) measuring the natural chemical variability of runoff and streams and linking these measurements to computer chemical and mass balance models.
ECONOMIC, SOCIAL AND LEGAL ASPECTS OF WATER QUALITY
(15) Economic Evaluation of Nonpoint Pollution Control (Hoehn).
Informed public policy requires information on the economic impact of nonpoint pollution control. This program would allow the Fellows to conduct research to better link the analytical methods of economics with physical and biological considerations.
The linkage between economic methods and biophysical information would be forged through research such as the projects now being carried out. Two current projects provide opportunities for examining these linkages. A project funded by the Michigan Department of Natural Resources examines the human behavior and economic responses to biological information about toxic concentrations in fish and aquatic environments. A USAID funded project in Cairo, Egypt, examines the economic benefits of environmental improvements obtained through investments in municipal wastewater conveyance and treatment.
(16) Societal Implications of Toxic Water Pollutants (Bronstein, Harris and Olsen).
All aspects of water toxicology have implications for society and, consequently, the government agencies that must deal with them. One important way to discover the influence of technical findings is to conduct case studies of individual episodes in depth enough to draw general conclusions.
This requires knowledge of toxicology, law, economics and sociology. Fellows may develop special emphases, depending on the particular cases selected for detailed study. Two possible areas of study are currently underway. One involves the decision making processes for alternative clean-up strategies at hazardous waste sites. The other is an evaluation of the social and economic development consequences of abandoned hazardous waste sites. Previous studies have been undertaken on the initial implementation of the Toxic Substances Control Act by the U.S. Environmental Protection Act and the role of public participation in pesticide decision making. The Water Science Fellows can select subjects for study to suit their backgrounds and interests after consultation with appropriate faculty.