[Availability of Se-rich Arable Land in High Geological Background Area and Suggestions for Zoning].

In order to promote the results of land quality geochemical surveys to serve the development of characteristic land resources and realize the safe utilization of Se-rich resources in high geological background areas, Wuli Town, Qianjiang District, Chongqing City were taken as the research object to evaluate the Se-rich level and heavy metal content of soil crops and carry out research on Se-rich cultivated area division and the availability method system in the high geological background area, in order to improve the utilization efficiency of Se-rich resources and provide ideas for the safe utilization of Se-rich resources in high geological background areas. The results showed that the soil and crops in the study area were rich in Se and had the potential to develop Se-rich resources, but some samples had the problem of excessive Cd. Soil pH was a key factor affecting the content of Se and Cd in crops, and alkaline conditions were conducive to the safe utilization of Se-rich resources. The areas of Class A-E (A:selenium-enriched arable land, B:crops that were not selenium-enriched but were safe, C:crops that were selenium-enriched but unsafe, D:crops that were not selenium-enriched and unsafe, and E:soil selenium content less than the selenium-enriched threshold and soil heavy metals not exceeding the standard)cultivated land were 0.72, 0.75, 0.28, 0.13, and 0.56 km2, respectively. It is recommended to develop safe and Se-rich resources in the distribution area of Class A cultivated land and to carry out soil acidification conditioning and low-accumulation crops in the distribution area of Class C and D cultivated land; other agronomic measures should be taken to reduce the risk of excessive heavy metals in crops and strengthen the protection of cultivated land in the region to prevent the input of new pollutants.