The Relative Importance of Factors Influencing Selenium Toxicity

Joy A. Gober

Abstract

	Selenium is the constituent most frequently identified as 
potentially impacting fish and wildlife species on irrigated lands in the 
States by the Department of Interior's National Irrigation Water Quality 
Program. Concentration of selenium is usually the first factor assessed. 
However, other factors should also be considered including the chemical form 
of selenium present, antagonism or synergism with other chemical constituents, 
substrate cation-exchange capacity, species sensitivity, exposure, dietary 
habits, behavior, age, vigor, water velocity, and temperature. In order to 
more effectively remediate for adverse impacts to fish and wildlife from 
selenium, accurate cause and effect relationships must be identified. A 
decision methodology that addresses the potential factors previously listed 
and guides the user toward the most appropriate focus is recommended. This 
approach might prove useful for potential future remediation sites and help 
ensure the most effective use of time, effort, and money.

KEY TERMS: Selenium; irrigation drainage; biota.