Environmental Geochemistry and Health最新文献

Lead (Pb) and cadmium (Cd) in soil threaten agroecosystem safety and human health. Due to the high bioavailability and mobility of heavy metals in red soil, the risk is further increased. Biochar is widely used for heavy metal immobilization, but original biochar suffers from inherent limitations. Most existing studies of iron (Fe)-manganese (Mn) modified biochar have not focused on red soil, and the relationship with soil-plant responses remains unclear. This study aimed to evaluate and compare the efficacy of sugarcane bagasse biochar (BC) and Fe-Mn modified sugarcane bagasse biochar (FMBC) for Pb and Cd immobilization in red soil, and clarify their effect on plant uptake. BC and FMBC were applied to Pb and Cd contaminated red soil for pot experiments with pak choi (Brassica rapa chinensis) as an indicator plant. The results showed that both BC and FMBC elevated soil pH, organic matter (SOM), enzyme activities, reduced Pb and Cd bioavailability, and transformed Pb and Cd to stable fractions. FMBC outperformed BC, and the 5% FMBC treatment achieved the optimal remediation efficacy. The 5% FMBC decreased the acid-extractable Pb and Cd by 9.33 and 34.40% compared to control. The plant biomass was significantly increased, Pb and Cd content in edible shoots met the limit standards, and bioconcentration (BCF) and translocation factors (TF) were lowered. Overall, this study establishes theoretical foundations and empirical bases for the application of FMBC to immobilize Pb and Cd in red soils, thereby providing a feasible and eco-friendly approach to support sustainable agriculture and the recycling of agricultural waste.

Soils in and around mining areas are frequently co-contaminated with heavy metals, posing risks to crop safety and human health. Nano zero-valent iron (nZVI) shows promise for multi-metal stabilization but is hindered by aggregation and oxidation. In this study, nZVI-supported attapulgite (nZVI@A) was synthesized by liquid-phase reduction and evaluated for stabilization of Cd, Cr, Cu, Ni, Pb, and Zn in contaminated mine soil and for reduction of maize metal uptake. Pot trials and stabilization tests were conducted, during which extractable fractions, sequential speciation, soil pH, CEC, EC, and metal concentrations and translocation in maize tissues were measured. Experimental results indicated that the stabilization effect was optimal at an nZVI-to-attapulgite mass ratio of 1:3. Significant reductions in extractable concentrations were observed for all target metals, with decreases in acid-extractable fractions and increases in residual fractions, indicating conversion to more stable forms and reduced bioavailability. Metal accumulation and translocation factors in maize were markedly lowered. The stabilization effect was attributed to synergistic adsorption by attapulgite and nZVI-driven precipitation and redox transformations. NZVI@A is proposed as a promising, potentially scalable in-situ amendment for multi-metal immobilization; field-scale validation and long-term stability assessment are recommended.

This study aimed to assess the lasting effects of early-life dioxin exposure via breastfeeding on the endocrine and reproductive health of children at 14 years of age, continuing a Vietnamese longitudinal cohort started in 2008. The participants were 68 mother-child pairs (38 from a dioxin hotspot and 30 from a non-exposure area). Serum steroid hormones in adolescents were quantified by liquid chromatography-tandem mass spectrometry and linked to their mother's breast milk dioxin congener levels collected within 4-16 weeks postpartum. Secondary sexual characteristics in girls and testicular volume in boys were clinically assessed. The results showed sex-specific differences. In girls from the hotspot, body weight and head circumference were significantly lower than those in the non-exposure area and showed negative correlations with specific dioxin congeners and steroid hormones. Hormonal analysis revealed significantly lower levels of estrone and estradiol, but higher cortisol levels, in both exposed genders. Estrone and estradiol displayed negative correlations with dioxins, stronger in girls. Conversely, cortisol showed positive correlations with most dioxin congeners and total toxic equivalents (TEQs) in boys only. Additionally, allopregnanolone levels were higher and positively correlated with dioxin in boys, while androstenedione and androstanediol were significantly lower in hotspot girls. Notably, testicular volume in boys did not differ or correlate with dioxin exposure. In conclusion, lactational dioxin exposure might associated with long-term, sex-specific disruption of steroid hormone homeostasis and impaired physical growth during puberty, particularly in girls.

The present investigation optimized and validated a modified QuEChERS analytical technique for extraction of residues from broccoli and soil matrices. Method validation demonstrated excellent linearity, no matrix effect (< 20%), recovery ranged between 80.26-102.52%, RSD < 20%, and LOQ of 0.01 mg kg^-1 ensuring accurate, precise, and sensitive residue detection in food and environmental samples as per European Union guidelines. 1st order dissipation kinetics model was best fitted with half-life of 1.97-2.61 days (chlorfenapyr), 2.29-2.67 days (fenvalerate), and 1.23-1.69 days (tolfenpyrad) on broccoli. The residues were below LOQ within 10-20 days, depending on insecticide and dose, while soil residues were below LOQ at harvest, indicating minimal persistence behaviour and reduced risk of environmental contamination. Dietary risk assessment revealed estimated daily intakes were well within acceptable safety thresholds, suggesting negligible acute and chronic health risks to the consumers. Furthermore, simple household practices, particularly immersion in 5% NaHCO₃ (46.94-69.75% reduction), significantly reduces surface residues, further lowering potential dietary exposure. Overall, the integrated evaluation of residue kinetics, soil contamination, dietary risk and mitigation strategies demonstrates that judicious use of these insecticides on broccoli poses a low risk to environment and public health. This study provides scientifically robust basis for the formulation of safer pesticide management strategies and evidence based, risk informed regulatory framework.

Groundwater is a critical resource for health, agriculture, and ecosystems in semi-dry regions. In the Karur district of Southern India, hard-rock aquifers serve as the primary source of drinking water. To evaluate seasonal variations in groundwater quality and fluoride (F^-) mobilization, 173 samples were analysed during the pre-monsoon (PRM) and post-monsoon (POM) periods. Hydrogeochemical processes, including halite dissolution, evaporation, silicate weathering, and ion exchange, were identified as major controls on groundwater chemistry. The evolution of faces from Ca-HCO₃ to Ca-Cl, Na-Cl, and Ca-Na-HCO₃ types reflects water quality degradations. Geochemical modelling confirmed saturation of halite, gypsum, dolomite, and fluorite, consistent with long-term rock-water interaction and fluoride release. Groundwater quality index (GWQI) revealed values ranging from 41 to 178, with better quality observed during the pre‑monsoon period. GIS‑based GWQI mapping highlights recharge dynamics, water-rock interactions, and anthropogenic influences. Elevated fluoride concentrations were observed in deeper aquifers (20-30 m) before monsoon recharge, with dilution reducing the level afterwards. Health risk assessment supported by Monte Carlo Simulation (MCS) revealed that children are vulnerable, with hazard quotients exceeding safe limits. These findings provide new insights into the hydrogeochemical evolution of hard rock aquifers. They emphasize the need for targeted fluoride mitigation strategies to safeguard public health in semi‑arid regions.

Source-specific probabilistic ecological risk assessment (PERA) of heavy metals (HMs) enhances risk management strategies. However, conventional methods, relied on total concentrations and deterministic parameters, may introduce considerable bias due to ignoring bioavailability and uncertainty. To address these limitations, this study conducted both concentration- and source-specific PERAs for HMs in Poyang Lake sediments using their bioavailable fractions and two-dimensional Monte Carlo simulation. Results reveled significant Cd pollution in sediments. Chemical speciation analyses indicated Cd (58.45% acid-soluble fraction) and As (36.96% specifically adsorbed fraction) exhibited high bioavailability, whereas Cr, Cu, Ni, Pb, and Zn were predominantly associated with residual fraction (48.55%-89.07%). Source apportionment identified three primary sources: mining/smelting, mixed sources, and industrial activities, with contribution of 26.87%, 34.55%, and 38.58%, respectively. Notably, mining/smelting was identified as the primary sources (77.68%), and As, Cd, and Pb emerged as targeted elements of concern. Incorporating bioavailable HMs into PERA reduced overall ecological risks by 38.09% compared to total concentration-based PERA. Corresponding source-specific ecological risk reductions were 39.21%, 42.11%, and 47.47% for mining/smelting, mixed sources, and industrial activities, respectively. This study highlights the importance of incorporating HM bioavailability and probabilistic analysis into ecological risk assessment framework for achieving accurate and realistic evaluation.

In southern Ghana, coastal aquifers are a significant water source but are frequently compromised by seawater intrusion, making them unsuitable for drinking and agriculture. This study evaluates seawater intrusion in central coastal communities using integrated hydrogeochemistry and spatial analysis. Sixty-seven groundwater samples from hand-dug wells and boreholes, collected during field measurements, were analysed for major-ion chemistry, nutrients, and metals. The study was analysed using combinations of geochemical plots, hydrochemical indices, and multivariate statistical methods. Total dissolved solids ranged from 120 to 42,431 mg/L (mean 2,158.75 mg/L). 26.47 per cent of the samples exceeded 1,500 mg/L for TDS. Thirty-nine per cent exceeded 200 mg/L for Na⁺, and 20.59 per cent exceeded 600 mg/L for Cl^-. TDS correlated strongly with Cl^- (r = 0.95) and Na⁺ with Cl^- (r = 0.93). EC-TDS ratios of 0.5-0.7 and Na⁺-Cl^- dominance on Piper plots indicated marine mixing. Gibbs plots showed rock-water control at moderate salinity and evaporation-mixing at high salinity. Evaporite phases remained undersaturated, supporting mixing and concentration rather than in situ salt dissolution. Positive chloro-alkaline indices signalled reverse ion exchange along saline fringes. Multivariate results separated two regimes. A large carbonate-buffered group represented inland fresh to slightly brackish waters. A smaller Na-Cl-rich group aligned with streams and near-coastal sites, localised saline end members and likely pathways for intrusion. This study recommends that water managers and the government prioritise sentinel-well monitoring in hotspots, seasonal pumping controls, protection of inland recharge zones, and targeted recharge enhancement.

Agricultural HNO₃ can affect mineral weathering, regional carbon cycling, and river NO₃^- pollution, which are linked to complex biological and hydrogeochemical processes. However, the involvement of HNO₃ in carbonate weathering and associated CO₂ fluxes is still not fully understood, especially in piedmont areas. Herein, 20 river water samples were collected from a typical piedmont region (Qingshui River basin) in September 2023 and analyzed for hydrochemical ions and multiple isotopes. The hydrogeochemical analyses, coupled with the Bayesian and forward models, and stoichiometric relationships, were employed to elucidate the major mechanisms underlying the release of HNO₃ from agricultural NH₄⁺ inputs and its quantitative effects on carbonate weathering and CO₂ sink flux. The hydrochemical evolution was driven by the piedmont strong runoff condition, resulting in the dominance of the HCO₃-Ca facies with less-soluble minerals. On the other hand, the riverine NO₃^- concentrations in the piedmont agricultural region were primarily derived from sewage and manure, with a mean contribution rate of 92.0 ± 2.07%. A large amount of NH₄⁺ from manure and sewage was rapidly oxidized through microbial nitrification, producing 35.9 ± 12.7 mg/L of HNO₃. According to the forward model results, carbonate weathering was the major contributor to water-rock interactions (49.8 ± 3.96%). Furthermore, carbonate rocks (mainly calcite) were preferentially and rapidly weathered by the produced HNO₃, increasing and decreasing the Ca²⁺ + Mg²⁺ concentrations and CO₂ sink flux by the end of the sampling period by 18.5 ± 6.21% and 13.0 ± 5.07%, respectively. Our study provides further insights into mineral weathering and carbon cycling associated with anthropogenic acids in piedmont areas.

Children in large Latin American cities may experience concurrent exposure to multiple environmental metals. This study quantified hair concentrations of lead (Pb), manganese (Mn), cadmium (Cd), mercury (Hg), and copper (Cu) in Bogotá schoolchildren to assess spatial heterogeneity across four administrative localities.Query In a cross-sectional design, 69 pooled scalp-hair samples from 14 public schools were washed, digested, and analyzed using atomic absorption spectrometry (flame, graphite furnace, and cold vapor, as applicable). Key quality control steps included blanks, certified-reference materials, matrix-spike recoveries, and instrument triplicates; batches not meeting precision criteria were reanalyzed or flagged (see Supplementary Tables S2-S9). Missing data were handled via multiple imputations. Inter-locality differences were assessed with Kruskal-Wallis tests, and multielement patterns compared using PERMANOVA. Statistically significant differences were found for Pb, Mn, and Cd (p < 0.05), with higher levels in Bosa and, to a lesser extent, Usaquén. Hg levels were low and spatially uniform. These findings support the use of school-based hair biomonitoring to detect spatially structured metal exposure and guide targeted environmental-health actions in urban settings.

Oil-based drilling cuttings residue (OBDCR) and fly ash (FA) are hazardous industrial solid wastes whose safe and cost-effective disposal remains an environmental challenge. This study addresses this issue by developing a novel approach to transform OBDCR and FA into value-added foamed ceramsite, thereby contributing to sustainable waste management and resource recovery. The primary aim was to optimize the synthesis parameters to produce a lightweight, high-strength, and environmentally stable material. Using OBDCR and FA as the main raw materials and borax as a fluxing agent, a univariate experimental design was employed to systematically investigate the effects of calcination temperature, duration, and foaming agent content on the material's properties. The ceramsite was characterized in terms of porosity, water absorption, compressive strength, acid/alkali resistance, and heavy metal leaching potential. Results demonstrated that under optimal conditions (850 °C, 1 h, 6% foaming agent, and OBDCR:FA:Borax = 35:35:30), the foamed ceramsite exhibited superior performance: 65% porosity, 14.9% water absorption, 4.02 MPa compressive strength, and acid/alkali resistance exceeding 99%. Critically, the leaching concentrations of heavy metals were significantly below the limits of Chinese national standard GB/T 5085.3, and multiple ecological risk assessment methods confirmed negligible environmental hazards. Pilot-scale experiments further validated the feasibility and economic potential of this approach. This work presents a novel, efficient, and low-risk pathway for the utilization of hazardous solid wastes, offering a practical inorganic material solution for industrial waste recycling and environmental protection.