The environmental chemistry of selenium in the San Bernard River

Abstract

Samples from the lower San Bernard River, located on the Texas Coastal Plain, were analyzed for selenium by the latest techniques of atomic absorption spectrophotometry. Concentrations as high as 50 ug/l soluble, 20 ug/l particulate, and 58 ug/l total selenium were detected. Seventy-one percent of all sediment contained selenium in the range of 0.3 to 5.1 ug/g. Algae samples contained from 0.3 to 5.5 ug/g in 89% of the samples. Selenium in water was predominantly soluble, except during high flow when particulate was more prevalent. Selenium was detected throughout the area during low and medium flows and only in the vicinity of a waste canal outlet during high flow. Factors affecting the distribution and environmental chemistry of selenium are discussed. Since selenium often exceeded the 10 ug/l level suggested to be hazardous to the marine environment by the Environmental Protection Agency, the possible adverse effects are reviewed to frame recommendations.