Geologic Sources, Mobilization, and Transport of Selenium from the CaliforniaCoast Ranges to the Western San Joaquin Valley: A Reconnaissance Study

摘要

The study is the first one of a selenium source area, the California CoastRanges, targeted as a problem area. The reconnaissance level study, started in 1984, is designed to examine the geologic sources of selenium in the Coast Ranges and to present a conceptual model of the dynamic processes of selenium mobilization and transport in stream and debris flows from the Coast Ranges to the west-central San Joaquin Valley floor. Identification of geologic source formations is based on samples of soils, geologic materials, efflorescent salts and stream sediments and associated seep and spring waters. Stream transport of selenium is based on analysis of streamflows which are in response to precipitation events, perennial springs which discharge directly into stream channels, and ephemeral pools. Mobilization processes are inferred from chemical characteristics and transformations of the element selenium in samples derived from identified source formations.