Co-contamination of heavy metals from antimony (Sb) mining poses significant threats to soil quality and human health. Although many studies have examined Sb sources, few have provided quantitative source apportionment combined with population-specific risk assessment. This study examined a representative Sb mining area in southwestern China through an integrated approach. The methodology combined Positive Matrix Factorization (PMF), Monte Carlo Simulation (MCS), the geo-accumulation index (I_geo), the enrichment factor (EF), the modified Nemerow pollution index (I_NI), and health risk assessment models. Results indicated a mean Sb concentration of 125.61 mg·kg⁻¹, nearly 50 times the regional background value (2.50 mg·kg⁻¹), with pronounced spatial variability (CV = 246.97%). PMF analysis revealed three major sources: regional mixed sources (36.8%), natural geological sources (30.1%), and industrial point sources (33.1%). MCS results suggested high ecological risks for Cd and Sb, with associated probabilities of 94.43% and 83.45%, respectively. The probability of non-carcinogenic risk (HI > 1) in children reached 85.61%. The total carcinogenic risk (TCR) exceeded acceptable thresholds for all individuals, with children showing higher susceptibility. Natural geological sources accounted for 57.9% of carcinogenic risk and 62.3% of non-carcinogenic risk in children. These findings underscore the urgent need for targeted pollution control and remediation strategies to mitigate both ecological and human health risks in Sb mining areas.

The co-occurrence of microplastics (MPs) and cadmium (Cd) in agricultural soils poses ecological risks, yet their interactions in flooded rice paddies remain unclear. Therefore, this study investigated the individual and combined effects of polyethylene MPs (mPE) and Cd on rice (Oryza sativa L.) growth, Cd accumulation, and soil microbial communities. Combined stress (5 mg/kg Cd + 1% mPE) significantly reduced rice growth (4.1–13.8% in plant height) and increased Cd accumulation in roots, stems, and seeds, driven by MP-enhanced Cd bioavailability. MPs altered soil pH, organic matter (OM), and moisture content (MC), indirectly suppressing yield. Microbial analysis revealed decreased bacterial alpha diversity (0.86–8.36%), favoring Cd-tolerant taxa (e.g., Solirubrobacteraceae), while fungal responses were weaker under flooding. Structural equation modeling indicated that Cd exerted direct toxicity through tissue accumulation, whereas MPs acted indirectly by modifying soil properties and inducing oxidative stress. Under co-exposure, MPs intensified Cd-induced oxidative stress, enhancing both direct and indirect toxicity pathways. Mantel tests identified DTPA-extractable Cd (r = 0.70) and OM (r = 0.55) as key drivers of Cd uptake. These findings highlight the complex interplay of MPs and Cd in rice paddies, with implications for managing co-contaminated agroecosystems.

Phosphogypsum (PG), a major by-product of the phosphate industry, has potential for improving acidic and nutrient-poor red soils, yet its agronomic benefits and heavy metal risks require systematic evaluation. A field experiment was conducted with five treatments, CK (soil only), GT (50% modified phosphogypsum, MPG), TT (40% MPG), ZT (50% phosphorite tailings), and DT (25% MPG + 25% lake sediment), to assess their effects on soil properties, enzyme activities, peanut growth, yield, quality, and heavy metal accumulation. All amendments improved soil structure, moisture retention, nutrient availability, and enzymatic activities. Peanut pod and kernel yields increased under all treatments, with DT achieving the greatest improvements (29.89% and 40.88%, respectively), whereas ZT showed the weakest response (1.91% and 6.26%). DT also achieved the highest soil quality index, and performed best in both yield improvement and root development. Although Cd accumulation increased under DT, heavy metal concentrations in peanut kernels remained below national food safety limits. Overall, DT was identified as the most effective amendment for enhancing red soil fertility and peanut productivity, while long-term monitoring of Cd bioavailability is recommended to ensure sustainable and safe application.

To address the contradiction between the widespread prevalence of selenium deficiency and the growing demand for selenium-enriched fruits, this study utilized phosphate tailings (industrial solid waste), wood vinegar (a by-product of forestry processing), biochemical fulvic acid, and alginic acid (renewable biomass resources) to construct an organic–inorganic composite soil selenium activator. This formulation enhances the mobilization of inherent selenium in the soil without relying on exogenous selenium supplementation, thereby improving selenium bioavailability while mitigating the environmental pollution and resource depletion associated with external selenium inputs. Through field experiments, we systematically evaluated the influence of varying activator dosages on soil physicochemical properties, available selenium content, selenium distribution in different citrus organs, and fruit quality. The results demonstrated that the application of the compound activator at 600 g/plant significantly increased (p < 0.05) soil available selenium and fruit selenium content by 21.26% and 21.06%, respectively. During the fruit expansion stage of Sugar Orange, soil available selenium was elevated by 21.8%, which corresponded to a 21.09% increase in fruit selenium content. Regarding fruit quality parameters, Sugar Orange exhibited increases in soluble solids (35.8%), citric acid (20.3%), solid-to-acid ratio (77.8%), and selenium content (223.3%). In Rock Sugar Orange, significant enhancements were observed in soluble solids (46.1%), vitamin C (45.3%), total soluble sugars (73.4%), solid-to-acid ratio (156.6%), and selenium content (69.7%). Structural equation modeling revealed that soil available selenium, soil properties, and selenium content in citrus organs collectively exerted positive regulatory effects on fruit quality. Specifically, juice selenium content showed significant positive correlations with fruit shape index, individual fruit weight, soluble solids content, and solid-to-acid ratio. This strategy achieves the synergistic reuse of industrial solid waste and agricultural biomass resources, offering a green and sustainable pathway to enhance selenium content and quality in citrus fruits.

The resourceful application of biogas slurry liquid (BSL) to farmland promotes circular agriculture, yet nutrient imbalances and potential heavy metal risks restrict its safe application. This study used Chinese cabbage (Brassica rapa L. ssp. pekinensis) to evaluate the agronomic and environmental impacts of BSL applied alone or combined with chemical fertilizers. Heavy metal safety was assessed using the pollution index, geoaccumulation index, and bioaccumulation coefficient. This study demonstrates that BSL application significantly increases soil available nitrogen. The co-application of medium-concentration BSL (0.1 L) with conventional chemical fertilizer effectively alleviates nutrient deficiency, resulting in the highest cabbage yield (e.g., peak total fresh weight of 5.12 g plant⁻¹ and plant height of 20.73 cm) and quality (soluble sugar reaching 4.21–4.31%, vitamin C at 16.3–17.3 μg g⁻¹). Based strictly on this short-term evaluation, no significant anthropogenic enrichment of heavy metals was detected in the soil, and heavy metal concentrations in the edible tissues of Chinese cabbage complied with China’s national food safety standards. While experimental observation of continuous accumulation was outside the scope of this study, predictive mass-balance modeling identifies Cd as the primary limiting factor for the long-term safe use of BSL. Compared with single BSL application, co-application with chemical fertilizers significantly mitigates the projected accumulation of soil environmental hazards (extending the safe utilization period to 27.3–54.6 years), and concurrently enhances both crop yield and quality. This study supports evidence-based decision-making for the safe agronomic reuse of BSL and its ecological risk assessment.