Geochemical Characteristics And Ecological Effects Of Selenium In Typical Geochemical Landscapes

Selenium is an essential trace element for human beings and animals.When selenium intake is insufficient or too low,it will lead to selenium deficiency and reduce immunity.The seleniumenters the human body mainly through the plant and the animal and so on,they all come from the soil.China is a country with poor selenium,72% areas are lack of selenium or low Selenium,and the population of 2/3 is lack of selenium intake.In recent years,the study on the geochemical characteristics and ecological effects of soil selenium has become a hot topic in the field of Applied Geochemistry in China and even in the world.Multi purpose regional geochemical survey has irised out manySe enriched area.the study shows that the total amount of selenium in soil is higher in some areas,but less then 5% can be absorbed and utilized by plants.Many study have shown that The seleniumenters the human body mainly through the plant and the animal and so on,they all come from the soil.So the study of origin,migration and activation of soil selenium in soil-crop system and the law of absorption and accumulation has important significance.In this paper,the geochemical characteristics of Selenium were analyzed and studied by using the data of 1:5 million land quality geochemical survey in the typical Selenium-rich landscape area.The results showed that:(1)CaO、MgO in soil Jiaozuo Boai County is mainly affected by the North rock weathering effect,SiO2 is mainly affected by the alluvial deposits in the southern Yellow Rive,Selenium presents the characteristics of high in the north and low in the south,it mainlyaffected by the northern rock weathering and soil forming secondary enrichment and pollution effects of human activities;(2)soil elements in XiantaoZhanggou townis mainly controlled by DongJing River,SiO2 and Na2 Owith high content in the region of near the river.Al2O3,TFe2O3 in the area away from the river is high,Se element with high background area is located in the middle and southeast of study area from the angle,the upper reaches of Enshi Ziyang,via the Yangtze River and Hanjiang river sedimentary;(3)Mianzhu Qitian town elements distributed in the study area is mainly affected by the northwest high background and the alluvial depositof Xiushui River,Mianyuan River and Shitingjiang,Se elements are high in the northwest,low in the southeast.The study area of wheat and rice enriched rate is high,Selenium content that higher than 0.04mg/kg accounted for 99.4%;Soil physical and chemical condition have a significant effect on Seleniumenrichment factor,between Se content and soil Se content of wheat and rice shows no significant correlation,There was a positive correlation between crop enrichment factorwith soil Na2O、SiO2 and pH,but negative correlation with soil S、P and organic carbon in three study areas.The results showed that the soil with high alkalinity and sandy content was beneficial to the accumulation of selenium in rice.