Toxics

Mining and smelting release potentially toxic elements (PTEs) that threaten ecosystems and public health. However, comprehensive risk assessments of PTEs across environmental media near mining areas remain scarce. The Laoguan River Basin is located in southwestern Henan Province, China. It lies within the water source area of China’s South-to-North Water Diversion Middle Route Project. This area has high geographic and ecological importance. In this study, we analyzed the pollution characteristics of PTEs in the water–soil–crop system. We also performed a source-oriented health risk assessment by integrating Monte Carlo simulation with source apportionment. According to this study, Mo and Sb were the predominant contaminants in soils and water. Pb, Cr, and Ni were elevated in crops. The health risk assessment indicated that PTEs in surface water were at acceptable levels. In contrast, PTEs in soils pose both non-carcinogenic and carcinogenic risks, particularly to children. The estimated risks were 1% (non-carcinogenic) and 64% (carcinogenic), with ingestion as the primary exposure pathway. Source apportionment showed that the surface water pollution was mainly linked to diverse mining activities. Soil pollution was jointly influenced by the geological background and mining and agricultural activities. Crop pollution was primarily associated with mining and agricultural activities. Geological background and mining were the main driving factors of the increased health risks for children. They accounted for 83% of the non-carcinogenic risk and 79% of the carcinogenic risk. Overall, these results are crucial for pollution control, safeguarding public health and safety, and promoting balanced economic and ecological development.

In this study, mulberry tree stems were used as raw material to prepare magnetic modified biochar, Fe-BC-500, using the co-precipitation method. The structure of Fe-BC-500 was systematically characterized and tested for arsenic (As) adsorption in batch experiments by varying parameters such as solution pH (3–11), the concentrations of co-existing anions (2–20 mg/L), and ionic strength (0–0.5 mol/L NaNO₃). The results indicate that Fe-BC-500 exhibited optimal adsorption capacity at pH 4 and an initial As(V) concentration of 20 mg/L. The influence of co-existing anions on As(V) adsorption followed the order PO₄³⁻ > SO4²⁻ > NO₃⁻. Kinetic analysis showed that adsorption of Fe-BC-500 on As(V) followed a pseudo-second-order kinetic model, with a correlation coefficient of 1.00, indicating chemical adsorption. The Langmuir model accurately described the isothermal adsorption results, indicating monolayer adsorption. Mechanistic analysis showed that As(V) was fixed on the Fe-BC-500 surface through complexation reactions, demonstrating adsorption specificity. This study provides a theoretical basis and highlights the application potential of magnetically modified biochar for removing As(V) from water.

With the widespread use of emerging contaminants such as melamine (MEL) and organophosphate esters (OPEs) as alternatives to traditional flame retardants, their ubiquitous presence in the environment has raised concerns about human internal exposure and health risks. Urine, as a critical matrix for biomonitoring, enables accurate assessment of internal exposure to these contaminants and their metabolites. This review systematically summarizes the research progress on urinary biomonitoring of MEL and its derivatives (cyanuric acid (CYA), ammeline (AMN), ammelide (AMD)) and OPE metabolites. It covers analytical methods (sample pretreatment including enzymatic hydrolysis and extraction, instrumental detection via HPLC-MS/MS/UPLC-MS/MS, and method validation), exposure characteristics (global spatial differences, population disparities among sensitive groups like children and e-waste workers, and temporal variations such as postprandial peaks), and health risk assessments. Results show that MEL and CYA are widely detected in urine (detection rates > 97%), with CYA dominating total MEL (66.2–80%); OPE metabolites exhibit regional compositional differences, e.g., bis(2-chloroethyl) phosphate (BCEP) in Shenzhen and diphenyl phosphate (DPHP) in New York. Current exposure levels are generally safe, but 2–12% of sensitive individuals face potential risks. This review highlights key challenges (method standardization, limited hydroxylated OPE standards) and provides directions for future research to establish a comprehensive exposure–health risk evaluation system.