Elements characteristics and ecological risks of farmland soil with typical heavy metal high background in Chongqing

¹ Chongqing Key Laboratory of Major Geological Events and Effects of resources and the environment (Chongqing Institute of Geology and Mineral Resources), 401120, China
² Observation and Research Station of Ecological Restoration for Chongqing Typical Mining Areas, Ministry of Natural Resources (Chongqing Institute of Geology and Mineral Resources), 401120, China
³ Chongqing Institute of geological survey, Chongqing 401122, China

^* Corresponding author: sportagang@163.com

Abstract

To investigate the characteristics of elements in selenium and cadmium rich soil and the ecological risk of local agricultural products in the typical heavy metal high background area of Chongqing,Taking the Se and Cd enriched soil in study area as a research object, The effects of Cd and Se on agricultural products were studied by collecting and analyzing the element contents and available contents of soil and agricultural products samples, The results showed that The pH value of soil in the study area is 6.89 ~ 8.22, which is alkaline and rich in organic matter; The study area belongs to the typical high background area of heavy metals. The content of Cd in the soil is 0.52 ~ 1.84 mg·kg-1, the average value is 1.26 mg·kg-1, the content of se is 0.41 ~ 0.77 mg·kg-1, the average value is 0.64 mg·kg-1, and its element characteristics are rich in selenium and cadmium; The activation rates of Cd and Se were 6.63 ~ 28.26% and 0.17 ~ 1.58% respectively; The concentration of Cd and Se in the soil of the study area may be mainly from the parent material of soil, and it is closely related to the content of organic matter in the soil. The local agricultural products are less affected by the high background value of heavy metals in the soil, and there is no excessive Cd in the agricultural products, among which potatoes and sweet potatoes have reached the standard of selenium enrichment. The research suggests that the soil rich in selenium and cadmium in the study area may come from the soil parent material, which is caused by the natural geological background and closely related to the content of organic matter in the soil. The activation rate of Cd and Se in the soil is low, which has little impact on the ecological risk of local agricultural products. This paper has important guiding significance for the development and utilization of selenium-rich soil resources in typical heavy metal high background areas.