DEATH IN THE MARSH by Tom...

DEATH IN THE MARSH by Tom Harris (Island Press: $14.95). As a reporter for the Sacramento Bee, Harris helped uncover the threat selenium poisoning poses to the California water supply. Classified by chemists as a metalloid, selenium is a micronutrient: Humans and animals require trace amounts of it, but in concentrations of more than a few parts per billion, the element is five times as toxic as arsenic. Dangerous levels that caused birth defects, reproductive failure and death in waterfowl were discovered in 1983 at the Kesterton National Wildlife Refuge, a complex of holding ponds designed to filter agricultural run-off water. The search for the sources of the contamination led Harris on a roundabout journey through much of the Western United States, where he took soil and water samples and conferred with doctors, geologists and ranchers. His conclusions, which originally appeared as a series of reports in the Bee, reveal that much of Western North America is threatened by selenium-laden rocks that form topsoil when they erode. The problem has been exacerbated by toxic run-off from excessive use of phosphorus fertilizers tainted with selenium, and feeding domestic animals selenium-spiked food. The rising concentrations of various selenium compounds in large areas of the San Joaquin Valley may render some of the most productive land in California unfit for agriculture during the next decade. This interesting but disturbing (and, at times, self-congratulatory) book would benefit from the inclusion of illustrations and better maps.