The concentrations of the heavy metals Pb, Cd, Cr, Hg, As, Cu and Zn in soil and locally produced grain (rice) were determined in paddy soil and rice around an abandoned high-arsenic coal mine area of Xingren county, southwest China. The health risk assessment was used to assess the multimedia and multipathway health risks of HM exposure in the study area. The results showed that the concentrations of As, Pb and Cd in soil were all higher than the corresponding limits for HMs in China. In terms of the accumulation and transfer capacity, Cd was more likely to transfer from the roots to rice, and its strong mobility may pose potential risks to local residents. The non-carcinogenic risks and carcinogenic risks of HM exposure in different media and exposure pathways were higher in children than adults. The total non-carcinogenic risks and carcinogenic risks in adults and children were higher than the standard limit values because of the HM exposure through ingesting rice husk. Among the exposure pathways evaluated, the contribution of diet was the largest, and As was the most important heavy metal in terms of the non-carcinogenic risk and carcinogenic risk factors. The total non-carcinogenic risks and carcinogenic risks caused by As in dietary crop (rice) accounted for 52% of the total in both adults and children. In order to maintain the health of residents in the study area, it is necessary to strictly strengthen the monitoring of heavy metal pollution in the study area and find effective soil improvement methods to reduce the health risks caused by heavy metal exposure.

Biochar can have multiple benefits, such as solid waste recycling, water pollution treatment, carbon fixation and sustainability, and it is green, friendly, inexpensive and highly efficient. Therefore, the present study aimed to investigate Cd(II) removal from aqueous solutions using pomelo peel derived biochar combined with a permeable reactive barrier (PRB). Meanwhile, the materials were characterized using SEM, FIIR, XRD, N₂ adsorption, Zeta potential, TGA and XPS. The removal conditions were optimized by a response surface methodology (RSM) and a back propagation combined with genetic algorithm (BP-GA). The results show that there were slight changes in the structure of the pomelo peel derived biochar before and after activation, while the variation was not significant. The specific surface areas of the not activated and activated pomelo peel derived biochars were 3.207 m² g⁻¹ and 6.855 m² g⁻¹, respectively. The pore diameter of the former was 4.165 nm and that of the latter was 4.425 nm, indicating that the two materials are mainly mesoporous. BP-GA is more suitable than RSM for optimizing the removal conditions of Cd(II) using the prepared materials combined with PRB. The maximum removal efficiency of Cd(II) was 90.31% at biochar dosage = 4.84, reaction time = 53.75 min, initial Cd(II) concentration = 19.36 mg l⁻¹ and initial pH = 6.07. The verification experiment was 88.74% under these experimental conditions, and the absolute error was 1.57%. The saturated adsorption capacity of quartz sand for Cd(II) is approximately 0.08 mg g⁻¹ when reaching equilibrium. The saturated adsorption capacity of biochar for Cd(II) is approximately 29.76 mg g⁻¹. Pseudo second order kinetics and Langmuir isotherm adsorption were more suitable for describing the Cd(II) adsorbed from an aqueous solution by activated pomelo peel derived biochar. The adsorption process of Cd(II) by the prepared biochar was spontaneous, endothermic and entropy driven. Our results suggest that the modified pomelo peel derived biochar can be regenerated within the fourth cycle and that it has application prospects as a useful adsorbent for water treatment in PRB systems. This finding provides a reference for relieving Cd pollution and for its large scale removal from wastewater when combined with a PRB system.

Background: Studies that address the changing characteristics of diseases are of great importance for preventing and controlling the occurrence and development of diseases and for improving health. However, studies of the epidemiological characteristics of noncommunicable diseases (NCDs) and malignant tumors (MTs) of the residents in Guiyang, China, are lacking. Objective: The aim of this study was to evaluate the prevalences of NCDs and MTs in residents of Guiyang, Guizhou Province, China, and analyze differences among ages, genders, and regions. Methods: A multistage stratified cluster sampling method was used. Based on the inclusion and exclusion criteria, 81,517 individuals were selected for the study. Of these, 77,381 (94.9%) participants completed the study. Structured questionnaires were used to collect information on demographic characteristics, NCDs, and MTs. The chi-square test (with 95% confidence intervals) was used to analyze differences in disease prevalence among genders, ages, and geographical regions. Results: The major chronic NCDs of Guiyang residents are obesity, hypertension, and diabetes. MTs in women are mostly breast cancer, cervical cancer, and endometrial cancer, whereas in men, MTs are mainly lung cancer, rectal cancer, and gastric cancer. The prevalences of hypertension and diabetes in women are higher than in men, but the prevalences of lung cancer and gastric cancer in men are higher than in women. The epidemiological characteristics of individuals in different life stages are dissimilar. In terms of regional distribution, the prevalences of the above diseases in the Baiyun and Yunyan districts of Guiyang are relatively high. Conclusions: Several NCDs (obesity, hypertension, and diabetes) and MTs (women: breast cancer, cervical cancer, and endometrial cancer; men: lung cancer, rectal cancer, and gastric cancer) should be the focus for the prevention and control of chronic diseases in the future. In particular, the Baiyun and Yunyan districts of Guiyang are the important regions to emphasize.

Reduced graphene oxide loaded with an iron-copper nanocomposite was prepared in this study, using graphene oxide as a carrier and ferrous sulfate, copper chloride and sodium borohydride as raw materials. The obtained material was prepared for eliminating hazardous dye carmine and the binary dye mixture of carmine and Congo red. The process of carmine dye removal by the nanocomposite was modeled and optimized through response surface methodology and artificial intelligence (artificial neural network–particle swarm optimization and artificial neural network–genetic algorithm) based on single-factor experiments. The results demonstrated that the surface area of the nanocomposite was 41.255 m²/g, the pore size distribution was centered at 2.125 nm, and the saturation magnetization was up to 108.33 emu/g. A comparison of the material before and after the reaction showed that the material could theoretically be reused three times. The absolute error between the predicted and experimental values derived by using artificial neural network–particle swarm optimization was the smallest, indicating that this model was suitable to remove carmine from simulated wastewater. The dose factor was the key factor in the adsorption process. This process could be described with the pseudo-second-order kinetic model, and the maximum adsorption capacity was 1848.96 mg/g. The removal rate of the mixed dyes reached 96.85% under the optimal conditions (the dosage of rGO/Fe/Cu was 20 mg, the pH was equal to 4, the initial concentration of the mixed dyes was 500 mg/L, and the reaction time was 14 min), reflecting the excellent adsorption capability of the material.