Advertisement

Science File / An exploration of issues and trends
affecting science, medicine and the enviroment. | Science
in Brief

Rock Formations Reported as Source of Water Pollution

October 22, 1998

Rock formations, not air pollution or clear-cutting of forests, are the source of excess nitrates in some California waterways, UC Davis researchers report in today's Nature. Nitrates cause massive algal blooms that use up dissolved oxygen and lead to fish kills. Biogeochemists Randy Dahlgren and JoAnn Holloway studied 40 miles of watershed along the Mokelumne River from Kirkwood to Jackson in the Sierra Nevada.

They found that nitrate levels were highest where the bedrock was composed of volcanic and sedimentary rocks that readily release nitrogen. One possible way to mitigate the high nitrate levels, they suggested, would be to plant more oak trees. Oaks remove more nitrates from soil than do the species now growing in the region.

Compiled by Times medical writer Thomas H. Maugh II

Advertisement
Los Angeles Times Articles
|
|
|