The occurrences, distributions, and risks of 55 target volatile organic compounds (VOCs) in water, sediment, sludge, and soil samples taken from a chemical industrial park and the adjacent area were investigated in this study. The Σ₅₅-VOCs concentrations in the water, sediment, sludge, and soil samples were 1.22–5449.21 μg L⁻¹, ND–52.20 ng g⁻¹, 21.53 ng g⁻¹, and ND–11.58 ng g⁻¹, respectively. The main products in this park are medicines, pesticides, and novel materials. As for the species of VOCs, aromatic hydrocarbons were the dominant VOCs in the soil samples, whereas halogenated aliphatic hydrocarbons were the dominant VOCs in the water samples. The VOCs concentrations in water samples collected at different locations varied by 1–3 orders of magnitude, and the average concentration in river water inside the park was obviously higher than that in river water outside the park. However, the risk quotients for most of the VOCs indicated a low risk to the relevant, sensitive aquatic organisms in the river water. The average VOCs concentration in soil from the park was slightly higher than that from the adjacent area. This result showed that the chemical industrial park had a limited impact on the surrounding soil, while the use of pesticides, incomplete combustion of coal and biomass, and automobile exhaust emissions are all potential sources of the VOCs in the environmental soil. The results of this study could be used to evaluate the effects of VOCs emitted from chemical production and transportation in the park on the surrounding environment.

Chromium slag sites pose severe environmental risks due to hexavalent chromium (Cr(VI)) contamination, characterized by high mobility and toxicity. This study focused on chromium-contaminated soil from a historical chromium slag site in North China, where long-term accumulation of chromate production residues has led to serious Cr(VI) pollution, with Cr(VI) accounting for 13–22% of total chromium and far exceeding national soil risk control standards. To elucidate Cr(VI) transformation mechanisms and elemental linkages, a combined approach of macro-scale condition experiments and micro-scale analysis was employed. Results showed that acidic conditions (pH < 7) significantly enhanced Cr(VI) reduction efficiency by promoting the conversion of CrO₄²⁻ to HCrO₄⁻/Cr₂O₇²⁻. Among reducing agents, FeSO₄ exhibited the strongest effect (reduction efficiency >30%), followed by citric acid and fulvic acid. Temperature variations (−20 °C to 30 °C) had minimal impact on Cr(VI) transformation in the 45-day experiment, while soil moisture (20–25%) indirectly facilitated Cr(VI) reduction by enhancing the reduction of agent diffusion and microbial activity, though its effect was weaker than chemical interventions. Soil grain-size composition influenced Cr(VI) distribution unevenly: larger particles (>0.2 mm) in BC-35 and BC-36-4 acted as main Cr(VI) reservoirs due to accumulated Fe-Mn oxides, whereas BC-36-3 showed increased Cr(VI) in smaller particles ( 0.7, p < 0.01), attributed to adsorption–reduction coupling on iron-manganese oxide surfaces. In contrast, Cr showed weak correlations with Mg, Al, Si, and K. This study clarifies the complex factors governing Cr(VI) behavior in chromium slag soils, providing a scientific basis for remediation strategies such as pH adjustment (4–6) combined with FeSO₄ addition to enhance Cr(VI) reduction efficiency.

Subtropical karst regions exhibit pronounced soil calcium (Ca) heterogeneity, posing unique challenges to crop growth and agricultural sustainability. Understanding soil–plant Ca migration mechanisms and plant adaptive strategies is vital for developing sustainable nutrient management in these ecologically sensitive areas. This study investigated mango adaptability to contrasting Ca environments by comparing Ca content, chemical forms, and subcellular distribution in soils and mango tissues between karst and non-karst regions in Baise, Guangxi, China. Results revealed that karst soils contained higher total Ca and all fractions, yet exhibited a lower proportion of bioavailable Ca compared to non-karst soils. Despite this, mango Ca contents in roots, stems, leaves, fruits, and seeds were 1.52-, 1.97-, 1.56-, 2.01-, and 2.07-fold higher in karst areas, respectively, following a transpiration-driven distribution pattern (leaves > stems > roots > fruits > seeds). However, bioconcentration and translocation factors did not differ significantly between regions ( P > 0.05), indicating that higher soil Ca does not proportionally enhance Ca enrichment or internal translocation efficiency. Chemical speciation analysis revealed distinct adaptive strategies: karst mangoes preferentially accumulated Ca as pectate in cell walls, enhancing structural integrity under high-Ca stress, whereas non-karst mangoes relied more on Ca oxalate storage and cytoplasmic Ca signaling to maintain homeostasis under Ca-limited conditions. Subcellular fractionation confirmed greater cell wall Ca allocation in karst mangoes versus cytoplasmic dominance in non-karst mangoes. These findings demonstrate how plants modify Ca chemical forms and subcellular partitioning to cope with contrasting Ca regimes, providing critical insights into adaptive mechanisms of perennial crops in karst ecosystems and informing sustainable agricultural practices in geologically complex regions.