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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.

Carbon sequestration refers to the technology of capturing carbon and storing it safely instead of directly discharging CO2 into the atmosphere. Rock salt is a promising CO2 reservoir, and the underground rock salt structure formed by salt cavern reservoirs in geological history has a natural sealing function. Storing carbon dioxide in salt caves can ensure that carbon dioxide is stably stored underground for a long time. However, at present, there are few studies on carbon sequestration in abandoned salt caves. This study analyses the characteristics of carbonate-evaporite strata in the high fold zone of eastern Sichuan and qualitatively evaluates Triassic carbonate-evaporite layers formed in the depth range of 800-3000 m in various sedimentary basins in Chongqing. A large set of carbonates-evaporites are developed in Chongqing, and the carbonate rocks near evaporites have low porosity and permeability, which can be used as CO2 storage caprock in salt cavities. Thick evaporated strata can also provide a good cover for CO2 storage in abandoned salt caves, which has great potential space resources.

A large area of soil in China is deficient in selenium (Se) and zinc (Zn)，meanwhile, Se and Zn are essential trace elements for human body, so it is of great significance to find Se and Zn rich soil to cultivate crops. Based on the data of Se and Zn in topsoil, crops and root soil obtained from 1:50000 land quality geochemical survey, this paper taking the western area of Fuling in Chongqing as the research area, studies the content and spatial distribution characteristics of Se and Zn in soil and crops, and analyzes the enrichment law of Se and Zn in agricultural crops. The results show that the average values of Se and Zn in the topsoil of the study area are 0.265mg/kg and 77.56mg/kg respectively. There are some differences in the contents of Se and Zn in different geological backgrounds, soil parent materials and soil types. The high value areas of Se and Zn are mainly distributed in the exposed areas of Triassic carbonate; in the study area, the average contents of Se and Zn in maize seeds are 0.029mg/kg and 20.752mg/kg respectively, and the enrichment rates are 96% and 82% respectively. The average contents of Se and Zn in rice seeds are 0.032mg/kg and 11.463mg/kg respectively, and the enrichment rates are 13.3% and 5% respectively. The bioaccumulation coefficients of Se and Zn in maize are higher than that in rice, and the availability of Se and Zn elements in maize root soil is higher.The results can provide geochemical basis for developing characteristic land resources, functional agriculture and promoting rural revitalization in Fuling District.