ABSTRACT

The shallow subsurface of the earth is an extremely important geological zone, one that yields much of our water resources, supports our agriculture and ecosystems, and influences our climate. This zone also serves as the repository for most of our municipal, industrial, and governmental

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wastes and contaminants, intentional or otherwise. Safe and effective management of our natural resources is a major societal challenge. Contaminants associated with industrial, agricultural, and defense activities in developed countries, the increased use of chemical pollutants resulting from the technological development of countries with evolving market economies, the increased need to develop sustainable water resources for growing populations, and the threat of climate and land use change on ecosystems all contribute to the urgency associated with improving our understanding of the shallow subsurface.