Study on Selenium Content of Surface Soils in Longhai, Fujian and Its Influencing Factors

Based on the data of geochemical soil surveys in Longhai, selenium content in soils and its influencing factors were investigated, which will provide information for the development of selenium-rich land resources. The total selenium contents of 4394 surface soil samples in Longhai, Fujian were analyzed by Atomic Fluorescence Spectroscopy (AFS). Results show that the total selenium concentrations in soils range from 0.031 to 2.361 mg/kg and the geometric mean is 0.354 mg/kg. The soil area of selenium-sufficient and selenium-rich accounts for 88.69% of Longhai City area. The results also indicate the parent materials, land use patterns, soil pH, organic matter and altitude were important influencing factors for selenium content. The contents of selenium in tuff and granite soils were higher than those in alluvium, diluvium and marine deposit. In different land use patterns, forest soils had the highest selenium content, and orchard soils and plough soils had moderate selenium content. The selenium content in surface soil had a significant positive correlation with altitude and organic matter and had a significantly negative correlation with soil pH, indicating that the selenium is enriched easily in acidic and organic matter-rich soils, especially in high altitude areas such as hilly areas with the obvious enrichment of selenium. This research provided valuable information for rational utilization of land and scientific development of the selenium-enriched industry.