Abstract

Watersheds are sources of our drinking water and are affected by a variety of toxic substances. Some of these toxic pollutants enter the watershed through direct introduction; however, the most serious problems of toxics found in the nation's water supplies are created through indirect means. Many toxics are introduced into the water supply through their movement through the biosphere. Two of these toxic substances are mercury and pesticides.

Mercury in the environment poses many risk-management challenges, including:

• Alternative treatment options for mercury-contaminated wastes
• In situ treatment of mercury in sediments
• Identification and control of diffusive sources of mercury
• Fate and transport of mercury in the watershed environment

Pesticides in the environment pose many risk-management challenges, including:

• Pesticide degradation and mixture characterization and behavior
• Pesticide application and transport data
• Reliability and effectiveness of pesticide occurrence modeling and pesticide management practices

This paper summarizes the current state of knowledge on the toxic sources, describes toxics’ effects on ecosystem and human health, discusses the challenges to the successful management of toxics, and outlines the suggested management-related research for watersheds.

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Teri Richardson

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