impractical to drill out suspect areas. Prediction of limestone sinkhole collapse will remain elusive until the triggering mechanisms are better understood.
Interdisciplinary Earth Science/Materials/Medical Research. Interdisciplinary research in these apparently diverse fields can provide a substantial opportunity to address major societal issues regarding health. This involves research into and public education about acceptable levels of risk in relationship to costs. Three examples are (1) the "asbestos hazard" where the relation between crystal size, shape, structure, and composition and chemical/ biological interaction is particularly important; (2) the radon concern; and (3) the presence and hazard to humans of trace elements present in the environment, especially if they may interact.
Radioactive Waste Isolation. To ensure the isolation of radioactive waste, which has been designated by the Congress to deep disposal only, hydrologic research on sedimentary and volcanic deposits plays an important role. Sedimentary deposits contain aquifers, which are the single most important reservoir for fresh water.
Groundwater Protection. Protecting groundwater quality requires monitoring and sampling, such as vadose zone sampling, sampling of volatile organic components in groundwater, and sampling volatile organic components that might affect employee safety. Improved methods for testing field permeability and in situ methods of measuring the physical and chemical properties of soil and rock are needed.
Organic Chemistry Control. Biological control of organic chemical reactions, especially in groundwater, is a rich area for research—research with a high potential monetary payoff in terms of current and ongoing expenditures for waste site remediation. Chemical reactions involving the fate of in situ organic compounds are controlled by soil microorganisms, and understanding the kinetics of such reactions poses a scientific challenge. Introducing an organism that produces a benign byproduct may be the cheapest way to remediate some forms of groundwater contamination. In many instances groundwater moves so slowly that colonies of microorganisms can actually move with the plume of contamination.
Waste Management: Landfills. The earth science community is equipped to develop management expertise for those materials that must be consigned to land burial.
Waste Management Geochemistry. A new field of geochemistry of waste management can be produced by recycling metals from waste.
Hazardous Waste Cleanup. In situ cleanup of uncontrolled hazardous waste sites vitally needs attention. The importance of fracture sealing of radioactive waste repositories in the subsurface cannot be overemphasized. Future generations should not be left with isolated pockets of hazardous material whose limits will undoubtedly become unknown with time.
Waste Disposal from Mining Operations. The problems with disposal of the waste from mining, milling, and in situ leaching need much greater emphasis, both for better understanding and, where possible, for mitigation of the potential adverse effects of exploiting and utilizing energy resources. Research and technological development are needed. Also, methods for site selection, characterization, and design of proposed repository sites for radioactive wastes have still not been developed.
Coal Mining and the Environment. The environmental impact of mining coals and their environmental acceptability as fuel are the most important aspects of coal research. Every stage of coal development, from exploration to consumption, has potential environmental impacts. Mine safety and mine site rehabilitation will also require research.
Nuclear-Energy-Related Wastes. Disposal of spoil waste at mine sites and of spent reactor material is the most important research area for nuclear energy. Recent concern about atmospheric carbon dioxide buildup, as well as about the increase in acid rain resulting partially from coal usage, may lead to a reevaluation of policies relating to nuclear power.
Global Change. The solid-earth scientist is the custodian of the past record of global change, and the research areas recommended in Chapter 3 are related to that record. Here the emphasis is on the most recent past.
Past Global Change. The record in ice cores, tree rings, deep-sea cores, lake-bed deposits, and surface features like sand dunes and glacial deposits is generally the most complete record of the recent