Heavy metal pollution is a serious problem worldwide. In this study, 41 soil samples and 32 cabbage samples were collected from the area surrounding the Jinsha coal-fired power plant (JCFP Plant) in Guizhou Province, southwest China. Pb, Cd, Hg, As, Cu and Cr concentrations in soil samples and cabbage samples were analysed to study the pollution sources and risks of heavy metals around the power plant. The results indicate that the JCFP Plant contributes to the Pb, Cd, As, Hg, Cu, and Cr pollution in nearby soils, particularly Hg pollution. Cu and Cr in soils from both croplands and forestlands in the study area derive mainly from crustal materials or natural processes. Pb, Cd and As in soils from croplands arise partly through anthropogenic activities, but these elements in soils from forestlands originate mainly from crustal materials or natural processes. Hg pollution in soils from both croplands and forestlands is caused mainly by fly ash from the JCFP Plant. The cabbages grown in the study area were severely contaminated with heavy metals, and more than 90% of the cabbages had Pb concentrations exceeding the permissible level established by the Ministry of Health and the Standardization Administration of the People’s Republic of China. Additionally, 30% of the cabbages had As concentrations exceeding the permissible level. Because forests can protect soils from heavy metal pollution caused by atmospheric deposition, close attention should be given to the Hg pollution in soils and to the concentrations of Pb, As, Hg and Cr in vegetables from the study area.

The content of heavy metals in the soil in Guizhou Province, which is a high-risk area for heavy metal exposure, is significantly higher than that in other areas in China. Therefore, the objective of this study was to evaluate the ability of CaCO₃ and clay to accumulate heavy metals in topsoil sample collected from Lixisol using the method of indoor simulation. The results showed that the contents of Cu, Zn, Cd, Cr, Pb, Hg and As in the soil sample were 10.8 mg/kg, 125 mg/kg, 0.489 mg/kg, 23.5 mg/kg, 22.7 mg/kg, 58.3 mg/kg and 45.4 mg/kg, respectively. The soil pH values increased with the CaCO₃ concentration in the soil, and the fluctuation of the soil pH values was weak after the CaCO₃ concentrations reached 100 g/kg. The adsorption capacity of lime soil increased by approximately 10 mg/kg on average, and the desorption capacity decreased by approximately 300 mg/kg on average. The desorption of all heavy metals in this study did not change with increasing clay content. Pseudo-second-order kinetics were more suitable for describing the adsorption kinetics of heavy metals on the soil material, as evidenced by the higher R² value. The Freundlich model can better describe the adsorption process of As on lime soil. The process of As, Cr, Cd and Hg adsorption on the soil sample was spontaneous and entropy-driven. Additionally, the process of Cu and Pb adsorption on the soil materials was spontaneous and enthalpy-driven. Generally, the adsorption and desorption of heavy metals in polluted soil increased and decreased, respectively, with increasing CaCO₃ content. The effect of calcium carbonate on the accumulation of heavy metals in soil was greater than that of clay. In summary, CaCO₃ and pH values in soil can be appropriately added in several areas polluted by heavy metals to enhance the crop yield and reduce the adsorption of heavy metals in soils.

Highly promising artificial intelligence tools, including neural network (ANN), genetic algorithm (GA) and particle swarm optimization (PSO), were applied in the present study to develop an approach for the evaluation of Se(IV) removal from aqueous solutions by reduced graphene oxide-supported nanoscale zero-valent iron (nZVI/rGO) composites. Both GA and PSO were used to optimize the parameters of ANN. The effect of operational parameters (i.e., initial pH, temperature, contact time and initial Se(IV) concentration) on the removal efficiency was examined using response surface methodology (RSM), which was also utilized to obtain a dataset for the ANN training. The ANN-GA model results (with a prediction error of 2.88%) showed a better agreement with the experimental data than the ANN-PSO model results (with a prediction error of 4.63%) and the RSM model results (with a prediction error of 5.56%), thus the ANN-GA model was an ideal choice for modeling and optimizing the Se(IV) removal by the nZVI/rGO composites due to its low prediction error. The analysis of the experimental data illustrates that the removal process of Se(IV) obeyed the Langmuir isotherm and the pseudo-second-order kinetic model. Furthermore, the Se 3d and 3p peaks found in XPS spectra for the nZVI/rGO composites after removing treatment illustrates that the removal of Se(IV) was mainly through the adsorption and reduction mechanisms.

Microplastics (MPs) entering the gastrointestinal tract of hosts through various pathways alter the community structure and metabolic activity of the gut microbiota, thereby affecting the normal physiological functions of the host. However, there is still huge knowledge gap in the effects of MPs on gut microbiota of organisms. This review mainly summarized comprehensively the response mechanism of gut microbiota of three typical organisms, including aquatic animal (fish), rodent (mouse), and soil animal (earthworm) after MPs entering their gastrointestinal tract. MPs pose substantial health risks to organisms, supported by increasing evidence from animal and human studies. MPs can impair the digestive systems of fish, mice, and earthworms, leading to reduce appetite, slow growth, and diminish reproductive capacity. Additionally, MPs can damage the intestinal mucosal barrier, further compromising health. MPs can increase the absorption of fat, and the lipase on the surface of lipid coated MPs can digest triglyceride, which maybe a potential mechanism leading to changes in fat metabolism. Meanwhile, this review also briefly elaborated a key step and important model for evaluating MPs using gut microbiota as the target organ. Ultimately, this review summarized the limitations in gut microbiota studies of MPs and their future development directions to better comprehend the effects of MPs on the animals and human gut microbiota.

Background: The secondary forests have become the major forest type worldwide, and forest gap was also a common small disturbance in secondary forests. We aimed to analyze the effects of small gap disturbance on the plant species richness of subtropical secondary forest with natural regeneration barriers and examine the relationship between soil topography and plant species in a subtropical Rhododendron secondary forest of the Baili Rhododendron National Nature Reserve. Methods: The major plant species and soil topography gradient factors of the small gaps and closed canopy (control group) were analyzed using two-way ANOVA, multivariate permutational analysis of variance, nonmetric multi-dimensional scaling, random forest, canonical correspondence analysis, redundancy analysis, and a generalized linear model. Results: Small gaps had significant impact on the distribution of soil available potassium (AK), organic carbon to total phosphorus (C/P) ratio rather than slope position for soil pH and calcium (Ca) under closed canopy. Soil pH and AK followed by total phosphorus (TP) were the most important variables explaining the spatial distributions of soil properties in both habitats. Determining the spatial distribution of individual woody plant species were soil pH in small gaps, instead of lower altitude, TP, total potassium (TK) and sodium (Na) concentrations for both habitats. Moreover, Ericaceae and Fagaceae were strongly associated with pH in the small gaps. However, there was soil Na for the herbaceous plant in the closed canopy. The species richness of woody plant species in small gaps was affected significantly by pH, soil water content (SWC), and TK, instead of soil organic carbon (SOC), SWC and C/P ratio in both habitats. Conclusions: Small gaps were not always significantly improved the composition of soil nutrients, but provided a good microenvironment for plant growth, species richness of major woody plant differed between habitats.