The objectives of this study were to compare the influence of land use, to determine which land has an impact on hydrochemistry and to clarify the impact of land use on soil microbial diversity and the correlation between hydrochemistry and soil microbial diversity. The impacts were assessed through chemical and biological data from 4 land-use groups. The results showed that soil microbial diversity and water chemical composition were different under different land uses. There was a strong correlation between the main hydrochemical components under different land uses, and the M03 had the highest correlation. The Shannon index was the largest for M01, the Simpson index was the smallest for M01, and the Chao1 and Ace indexes were the largest for M02. Actinobacteria, Proteobacteria and Acidobacteria were the dominant bacteria with different land uses, and some bacteria were present or absent depending on the land use. It was found that the soil CO2 content was different with different land uses. Soil CO2 content, hydrochemistry and soil microbial species were related to each other. A heatmap analysis showed that the F− and soil CO2 content showed a strong correlation with soil microorganisms and that the dominant bacteria were positively correlated. Under different land uses, hydrochemistry, soil CO2 and soil microorganisms interact with one another.

Local officials play active and important roles in the high-quality agricultural development process in China. In this study, the DEA-SBM model was used to measure the level of agricultural quality development in China, and Tobit regression was conducted to analyze the impacts of officials on agricultural quality development in China. The results showed that between 1997 and 2016, the agricultural GTFP exhibited a downward trend before following an upward trend in China. The personal characteristics of officials had important effects on the development of agricultural quality. In different development stages, officials had diverse effects on agricultural quality development.

No abstract

Fluorine is an essential nutrient, and excessive or deficient fluoride contents in water can be harmful to human health. The shallow groundwater of the Jiaolai Basin, China has a high fluoride content. This study aimed to (1) investigate the processes responsible for the formation of shallow high-fluoride groundwater (SHFGW); (2) identify appropriate methods for in situ treatment of SHFGW. A field investigation into the formation of SHFGW was conducted, and the results of experiments using soils from high-fluoride areas were examined to investigate the leaching and migration of fluoride. The results showed that the formation of SHFGW in the Jiaolai Basin is due to long-term geological and evaporation processes in the region. Stratums around and inside the basin act as the source of fluoride whereas the terrain promotes groundwater convergence. The hydrodynamic and hydrochemical conditions resulting from slow groundwater flow along with high evaporation and low rainfall all contribute to the enrichment of fluoride in groundwater. In situ treatment of SHFGW may be an effective approach to manage high SHFGW in the Jiaolai Basin. Since soil fluoride in high-fluoride areas can leach into groundwater and migrate with runoff, the construction of ditches can shorten the runoff of shallow groundwater and accelerate groundwater loss, resulting in the loss of SHFGW from high-fluoride areas through river outflow. The groundwater level will be reduced, thereby lowering the influence of evaporation on fluoride enrichment in shallow groundwater. The results of this study can act a reference for further research on in situ treatment for high-fluoride groundwater.

The water quality of the rainwater is obviously different from that of the groundwater after it reaches the surface and passes through the vadose zone. This study aims to further evaluate and analyze how soil CO 2 changes under natural conditions, to provide a theoretical background for the establishment of CO 2 geological storage, and to provide a basis for the detection of CO 2 leakage in order to provide insights for expanding CO 2 research. The changes in soil CO 2 concentration under different conditions were simulated and analyzed by laboratory experiments, and the effects of CO 2 on water chemical composition were also analyzed. In this study, two experimental groups (vegetation group (V) and high-temperature sterilization group (R)) and one blank group (B) were established. The results showed that the CO 2 concentration in column R was the lowest, while that in column V was the highest. With rainfall infiltration, soil CO 2 concentration gradually increased. When the rainwater infiltrated to 215 cm, the CO 2 concentrations in the columns V, B, and R were 5100 mg•m −3 , 4450 mg•m −3 , and 32,000 mg•m −3 , respectively. At infiltration depths from 5 to 215 cm, the Na + , Ca 2+ , Mg 2+ , SO 4 2− , and HCO 3 − concentrations in columns V and B decreased, whereas they increased in soil column R. The simulation revealed that the CO 2 concentration ranged from 560 mg•m −3 to 50,000 mg•m −3 ; pH value decreased; NO 3 − and Cl − remained stable; SO 4 2− decreased; and fCO 2 , HCO 3 − , Ca 2+ and Mg 2+ increased.