INTRODUCTION

This report contains papers presented at the seventh Technical Meeting of the U.S. Geological Survey (USGS), Toxic Substances Hydrology (Toxics) Program. The meeting was held March 8-12, 1999, in Charleston, South Carolina. Toxics Program Technical Meetings are held periodically to provide a forum for presentation and discussion of results of recent research activities.

The objectives of these meetings are to:

The Proceedings is published in three volumes. Volume 1 contains papers that report on results of research on contamination from hard-rock mining. Results include research on contamination from hard rock mining in arid southwest alluvial basins, research on hard rock mining in mountainous terrain, and progress from the USGS Abandoned Mine Lands Initiative. This Initiative is designed to develop a watershed-based approach to characterize and remediate contamination from abandoned mine lands and transfer technologies to Federal land management agencies and stakeholders.

Volume 2 contains papers on contamination of hydrologic systems and related ecosystems. The papers discuss research on the response of estuarine ecosystems to contamination from human activities. They include research on San Francisco Bay; mercury contamination of aquatic ecosystems; and investigation of the occurrence, distribution, and fate of agricultural chemicals in the Mississippi River Basin. This volume also contains results on development and reconnaissance testing of new methods to detect emerging contaminants in environmental samples.

Volume 3 contains papers on subsurface contamination from point sources. The papers discuss research on: hydrocarbons and fuel oxygenates at gasoline release sites; ground-water contamination by crude oil; complex contaminant mixtures from treated wastewater discharges; waste disposal and subsurface transport of contaminants in arid environments; ground water and surface water affected by municipal landfill leachate; natural attenuation of chlorinated solvents; and characterizing flow and transport in fractured rock aquifers.

In all, the more than 175 papers contained in this proceedings reflect the contributions of more than 350 scientists who are co-authors. These scientists are from across the USGS, as well as from universities, other Federal and State agencies, and industry.

More information on the Toxic Substances Hydrology Program, including a searchable bibliography of publications and selected on-line publications, is available on the World Wide Web at: http://toxics.usgs.gov/

ACKNOWLEDGMENTS

The editors acknowledge with great appreciation the assistance provided by Kim Crutchfield, Judy Salvo, Nana Snow, Judy Griffin, Patti Greene, and Ray Douglas. Their efforts in the planning, organization, and arrangements made for this seventh Technical Meeting of the Toxics Program made it both successful and enjoyable. Sincere thanks to Bill Ellis for assisting authors with preparation of papers for publication and for preparation and layout of this manuscript. Chet Zenone, Larry Slack, Anthony Buono, and John Flager assisted through review and improvement of the papers in this proceedings. Thanks are extended to the South Carolina District for their warm hospitality. Thanks also to the many scientists whose contributions and accomplishments are reflected in this proceedings; their continued efforts ensure continued success for the USGS Toxic Substances Hydrology Program.