Factors controlling the transport and transformation of selenium in typical soil environments: a case study of the Chengdu economic zone in Sichuan Province

Abstract：Selenium is an essential trace element which is beneficial for people’s health and has significant cancer-fighting properties. More and more people have attached importance to this element, which has produced great economic efficiency. The inadequateness or excessiveness of selenium content and different forms of selenium in soil can affect the plant growth directly and then bring about further influence on the health of human beings and animals by food-chain. So It’s significant to study the transport and transformation of selenium in the soil profile. In this paper, 4 soil profile samples of PM2, PM8, PM9, PM11 were collected from Chengdu economic zone in Sichuan Province according to different soil types. The authors analyzed the content of total selenium and the available selenium content in the soil profiles. By cultivating soil solution the authors also obtained the total selenium and the available selenium content both in soil solution and in soil debris. Then the authors calculated the distribution coefficient of selenium in the soil solution. The result indicates that the total selenium and available selenium were well concentrated at the surface of these four soil profiles. The content of available selenium shows a significantly positive correlation with the total selenium and a positive correlation with the soil organic matter. By calculating the distribution coefficient of selenium (Ki) in different types of soil, the authors have reached the conclusion that the distribution coefficient of selenium is gradually concentrated from deep to top soil. Furthermore, the coefficient of selenium also shows a positive correlation with soil pH and the soil organic matter. This study also suggests that the total selenium, the soil pH, the soil organic matter and the clay fraction are the main factors affecting the transport and transformation of selenium to plant in different types of soils. The transport of selenium with the migration of the soil solution in the vertical soil profiles is not obvious.