MIGRATION AND ENRICHMENT OF SELENIUM IN SOIL-PLANT SYSTEM IN BAIQUAN AREA, HEILONGJIANG PROVINCE

Based on the 1:50 000 land quality geochemical survey data of Baiquan area in Heilongjiang Province, the paper studies the geochemical characteristics and ecological effects of selenium(Se), and discusses the migration and enrichment rule of Se in soil-plant system. The results show that the Se content in root soil is averagely 0.25×10^-6, belonging to medium Se-rich soil, with higher Se-rich percentage in soybean and rice. The Se contents in water-soluble and ion-exchangeable forms together account for about 5%, which restricts the available content of Se to some extent. The physicochemical properties of soil have important effect on total Se, Se forms and migration-enrichment. Specifically, Se content in alkaline-neutral soil is not affected by pH, mainly existing in the form of selenite, which is not conducive to the transfer of Se and plant absorption. The total Se (available content) is positively correlated with organic matter. However, when the content of organic matter exceeds a certain limit, its increase can improve the Se content, but also inhibit the migration and enrichment of Se.