[Characteristics of Soil Selenium-cadmium Migration and Accumulation and Its Bioeffectiveness in Typical Geological High Background Area].

The prevalence of selenium-cadmium （Se-Cd） symbiosis in soils of geologically high background areas directly affects the safe utilization of Se-rich land resources. To investigate the migration and accumulation characteristics and bio-effectiveness of Se-Cd in the soil-crop system in typical geological high background areas of Southwest China and to realize the safe use of natural Se-rich land resources in geological high background areas, we collected 84 samples of agricultural crops （maize） and their supporting root systems and analyzed the Se-Cd content and physicochemical properties. Se-Cd accumulation characteristics, influencing factors, and bio-effectiveness of the soil-crop system were evaluated using geostatistics, bioenrichment factors, and geographic detectors. The results showed that the Se-Cd content in the study area was significantly higher than the background value of the soil in the whole country and in Yunnan Province. Influenced by the geological background, secondary enrichment in the process of soil formation, and agricultural activities, the accumulation and enrichment characteristics of Se in the root soil varied from no enrichment to slightly enriched, and the occurrence form was dominated by the residue state. The accumulation index of soil Cd was mainly in the medium pollution level, and the occurrence form was mainly in the residual state and the combined state of iron and manganese. The Se-enrichment rate of crop seeds reached 98.8% （DB 50/T 524-2013 standard）, and the average value of bioconcentration factor was 5.8%. The exceeding rate of Cd content in crop seeds was only 1.19% （GB 2762-2022 standard）, and the average value of Cd bioconcentration factor was 2.11%, so the ecological risk of heavy metal Cd in crop seeds was relatively low. In the Se-Cd symbiosis area under geological background, the weak alkaline environment of the soil could effectively reduce the bioavailability of Cd in crop seeds, and the Se-rich soil could inhibit the uptake of Cd by the crops to a certain extent. Correlation analysis showed that the migration and accumulation of Se and Cd from soil to crop seeds in the soil-crop system were affected by the elemental accumulation pattern and the physical and chemical properties （pH） of the soil, and at the same time, there was a certain synergistic-antagonistic effect between Se and Cd in the soil-crop system. Correlation analysis showed that the migration and accumulation of Se and Cd from soil to crop seeds in the soil-crop system was influenced by the occurrence of elements, soil physicochemical properties （pH）, and other factors, and there was also a certain synergistic-antagonistic interaction between Se and Cd in the soil-crop system.

[Potential Ecological Risk Assessment and Source Analysis of Heavy Metals in Soil-crop System in Xiong'an New District].

In order to evaluate the distribution characteristics of fluorine geochemistry in the surface soil and human health risk in Xiong'an New District, GIS spatial analysis and correlation analysis were used to analyze the depleted and enriched features and influencing factors of soil fluoride and to carry out the soil fluoride health risk assessment. The uncertainty of the health risk assessment results was studied based on the Monte Carlo stochastic simulation. The results showed that the average content of fluorine was 641 mg·kg-1, which was 1.34 times the background value of the national A-layer soil. The excess fluorine and high-grade samples accounted for more than 85%, and the overall soil fluorine content was relatively high. The average content of fluoride of the irrigation water samples was 0.85 mg·L-1, the spatial distribution characteristics of which were affected by the hydrochemical type and flow direction of shallow groundwater. The vertical spatial variation of soil fluoride, mainly affected by the vertical distribution of soil physicochemical properties such as soil organic carbon and texture, was not obvious. The depletion and enrichment of topsoil fluorine was mainly controlled by the geological background, and its spatial distribution was affected by external inputs, such as human factors (agricultural irrigation water, fertilization, and atmospheric dry and wet deposition). The soil fluoride content was significantly correlated with the iconic indicators of the geomorphological environment, including the content of Al2O3, Fe2O3, MgO, K2O, soil organic carbon (Corg.), cation exchange capacity (CEC), clay, and silt (P<0.01). The results of human health risk assessment showed that oral intake was the main exposure risk route of soil fluoride. The non-carcinogenic health risk index HQ of adults was less than 1, and the harm could be ignored. The probability of non-carcinogenic health risk exceeding the threshold for adults and children was 34.3% and 27.6%, respectively, and daily soil intake was the most sensitive parameter.

[Factors Affecting the Translocation and Accumulation of Cadmium in a Soil-Crop System in a Typical Karst Area of Guangxi Province, China].

To understand the main factors influencing the translocation and accumulation of cadmium (Cd) in soil-crop systems in typical karst areas, 68 sets of paddy soil and rice grain samples were collected in Guangxi Province. These were used to analyze Cd concentrations and soil properties (pH, organic matter (OM) content, oxide content, and texture). Spearman's correlation coefficients and principal component analysis (PCA) were used to examine the effects of soil properties on Cd concentrations and identify the main influencing factors. The studied soils were highly enriched in iron oxide (TFe2O3), aluminum oxide (Al2O3), and manganese oxide (MnO) compared to background levels, with average concentrations of 20.2%, 19.0%, and 0.2%, respectively. However, the soils are relatively depleted in silica (SiO2), with an average concentration of 41.0%. The soils are strongly weathered and leached in study area, giving rise to rich occurrences of Fe-Mn nodules. The concentrations of TFe2O3 and MnO in the study soils were significantly correlated with soil Cd, rice seed Cd, and the Cd bioconcentration factor (BCF). The PCA analysis further showed that TFe2O3 and MnO in soils were the main factors affecting the migration and enrichment of Cd while soil pH, OM, and Al2O3 had less of an influence. Furthermore, SiO2 and soil texture indirectly affected the migration and enrichment of Cd. It is suggested that the Fe-Mn nodules effectively adsorb and immobilize Cd in the study area soils, acting as a heavy metal scavenger that reduced the biological accessibility of Cd.

miR-125a inhibits the migration and invasion of liver cancer cells via suppression of the PI3K/AKT/mTOR signaling pathway.

In order to explore the regulation of the invasive ability of hepatocellular carcinoma cells and the underlying mechanism, mimics sequences of microRNA (miR)-125a (miR-125a-3p/5p) and scramble sequences (miR-125a-3p-s/5p-s) were transfected into human hepatocellular carcinoma cell lines, HCC-LM3 and HepG2, and the non-malignant epithelioid hepatic cell line QZG. To inhibit and upregulate the expression of miR-125a individually. Protein expression was detected by western blotting, and the cell proliferation and migration abilities were evaluated by soft agar colony formation and Transwell assay, respectively. It was revealed that the expression of miR-125a was downregulated in HepG2 and HCC-LM3 cells compared with that of QZG cells, and expression was markedly lower in HCC-LM3 cells than that in HepG2 cells (P<0.01). The colony formation and migration rates of the cells transfected with miR-125a-3p/5p were decreased compared with negative controls, but were increased in cells transfected with miR-125a-3p-3/5p-s (P<0.01). The protein and messenger RNA expression of phosphoinositide 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) was decreased following transfection with miR-125a-5p, whereas expression was increased compared with negative controls following transfection with miR-125a-5p-s (P<0.01). Furthermore, the proliferation and migration abilities of cells were attenuated following inhibition of the PI3K/AKT/mTOR pathway by LY294002. The results of the present study indicated that miR-125a inhibits the invasive ability of hepatocellular carcinoma cells via regulation of the PI3K/AKT/mTOR pathway.