SELENIUM: ABUNDANT SOIL SURVEY AND ASSESSMENT IN ZHEJIANG
浙江富硒土壤资源调查与评价

A recent survey found that there are large areas of soils with abundant selenium in Zhejiang. Among different types of soils, Se concentration in calcareous rock soil is the highest. Calcareous rock soil, yellow soil and red soil belong to selenium-enriched soils. In different parent materials, selenium concentration in all kinds of eluvial-slope wasp is higher than that of others, and it is up to 0.43mg/kg. Selenium concentration in same rocks, such as quartz sand rock, silicon rock, middle and deep metamorphic rocks is higher than that of the Earth's crust of rocks in Eastern China. The soil with abundant selenium is from the rocks with abundant selenium and coal formation. The variety of selenium content in soil profiles shows that selenium tends to be enriched in top soil, and it decreases rapidly from top soils to deep layer especially in parent material. It is obvious that Se in rock is the Se source of soil. This means selenium is enriched during soil formation and probably a part of selenium is from air deposition. The average enrichment coefficient of selenium in soils of Northern Zhejiang is up to 1.94, but that in the coastal hilly plain of Eastern Zhejiang is 1.14, which is similar to that in the hilly basin of Middle Zhejiang with enrichment coefficient of 1.34. The soil with abundant selenium can be recognized considering its enrichment coefficient and ecological landscape soil selenium criteria. The soils with abundant selenium can be divided into three sections dependent on selenium enrichment coefficient, selenium-abundant area, and selenium bio-availability in soil.