WATER SELENIUM SPECIATION AND SEDIMENT FRACTIONATION IN A CALIFORNIA FLOW-THROUGH WETLAND SYSTEM

Selenium speciation and sediment fractionation. In a wetland system, selenium mass balances were performed between water and sediments as a function of time (2 years). Extraction and analysis procedures are described for Se (0), Se (IV), Se (VI) and organic matter associated with Se. Selenium accumulation, transformation and incorporation are found to be intensified on the surface of sediment and decrease with depth. Selenium was removed with the water flow but in sediment, reduction (Se°) and immobilization into organic phase were the major reaction mechanisms.