Valence State Changes and Bioavailability of Selenium in Soil Treated with Selenite and Selenate

Pot experiments were conducted to study valence state changes and bioavailability of selenium in soil treated with selenite and selenate.The objective of the study was to provide information for bioavailability,biogeochemical cycling and environmental action of selenium in soil.The results showed that the total selenium,Se(Ⅳ) and Se(0) concentration of the soil treated with slenite increased significantly with the increase of selenium concentration at different growth stages of pakchoi.In different growth phases,soil total selenium,Se(Ⅳ),Se(VI) and Se(0) concentration increased remarkably when selenate concentration increased.The valence state changes of selenium were observed in soil treated with selenite and selenate.Se(Ⅳ) and Se(VI) were transformed into Se(0) with the growth of pakchoi.Roots were the dominant sites for selenium accumulation in slelenite-supplied pakchoi,whereas shoots were the major sinks for selenate accumulation.Shoots and roots seleniun content in selenate-treated pakchoi were significantly higher than that in selenite-treated pakchoi.The bioavaibility and mobility efficiency of selenate in pakchoi were greater than selenite.Selenium accumulation in pakchoi was more contributed to soil Se(VI) concentration than other valence selenium.