Environmental Geochemistry and Health最新文献

Graphitic carbon nitride (g-C₃N₄), a metal-free polymeric semiconductor, has attracted increasing attention for photocatalytic and biomedical applications due to its visible-light responsiveness, tunable electronic structure, and chemical robustness. However, its practical utility remains constrained by poor crystallinity, limited active surface sites, and rapid electron-hole recombination. In this study, a facile one-step calcination strategy was employed to synthesize highly crystalline, non-metal-doped g-C₃N₄ nanostructures with enhanced physicochemical properties. Structural and optical characterizations revealed improved crystallinity, expanded surface area, defect-rich architecture, and extended visible-light absorption. These features significantly boosted the photocatalytic performance for the degradation of Reactive Blue 222, achieving up to 89% removal within 90 min under visible light, with the degradation kinetics following a pseudo-first-order model (k = 0.97 min⁻¹). Beyond environmental remediation, the modified g-C₃N₄ also demonstrated notable anticancer activity against HCT-15 (colon cancer) cell lines. Cytotoxicity assays revealed concentration-dependent inhibition, with IC₅₀ values of 7.10 µg/mL, respectively, indicating its potential as a photodynamically active nanomaterial for cancer therapy. The dual functionality of visible-light-driven photocatalysis and selective anticancer activity underscores the potential of engineered g-C₃N₄ as a sustainable platform for integrated environmental and biomedical applications.

Radon, a naturally occurring radioactive gas produced from the decay of uranium in the subsurface, migrates upward through soil by diffusion and advection before being released into the atmosphere. As the second leading cause of lung cancer after smoking, understanding its behavior in the near-surface environment is essential for assessing environmental radiation risks. This study investigates depth-wise radon concentrations in soil gas, surface exhalation rates, and transport parameters in the soil of Chakrata region,  Garhwal Himalaya, India. Radon measurements were performed using a portable Smart RnDuo monitor at depths (Z) of 15, 30, and 45 cm. Soil-gas radon concentrations ranges from 237 to 6540 Bq m^-3 at 15 cm, 854 to 7831 Bq m^-3 at 30 cm, and 1020 to 8540 Bq m^-3 at 45 cm, indicating a systematic increase with depth. Surface exhalation rates varies between 1.25 and 16.19 Bq m^-2 h^-1, with a mean value of 6.42 Bq m^-2 h^-1, respectively. Radon transport parameters were derived using Fick's diffusion model, resulting in average values of 0.49 m for diffusion length (l_s) and 0.002 m²s^-1 for diffusion coefficient (D_s). Spearman's rank correlation analysis revealed that surface radon exhalation and diffusion parameters exhibit strong correlations. These findings provide baseline information on radon mobility and soil-gas dynamics in the region and will support future radon hazard assessment and environmental monitoring efforts in the Chakrata area of the Lesser Indian Himalaya.

The development of efficient and sustainable adsorbents is crucial for remediation heavy metal contamination in both aqueous and terrestrial environments. Biomass-derived biochar shows great promise, yet its adsorption performance is highly dependent on both the feedstock properties and the pyrolysis temperature. However, a systematic understanding of how temperature dictates the adsorption mechanisms, especially for multi-metal systems, remains limited for novel biomass precursors. Therefore, the stem pith of Medulla stachyuri (MS) was utilized to prepare biochars at different pyrolysis temperatures (400, 600, and 800 °C, denoted as MBCs) and to investigate their adsorption behavior for Pb²⁺ and Cu²⁺. The results indicated that higher pyrolysis temperatures significantly enhanced the specific surface area (reaching 322.94 m²/g for MBC-800) and ash content but decreased the oxygen-containing functional groups. MBC-800 exhibited superior adsorption capacities for Pb²⁺ (2139.25 mg/g) and Cu²⁺ (970.68 mg/g), with remarkable selectivity for Pb²⁺ in binary systems. Mechanistic studies revealed that the dominant adsorption mechanism shifted from surface complexation at lower temperatures to precipitation induced by the biochar's inherent inorganic components (e.g., SO₄²⁻ forming PbSO₄) at higher temperatures. Component contribution analysis quantitatively confirmed that the water-soluble fraction in MBC-800 was responsible for over 78% of Pb²⁺ immobilization. Furthermore, MBC-800 demonstrated excellent stability with the lowest desorption rate, indicating a low risk of secondary pollution. This work highlights the superiority of high-temperature biochar from MS for efficient and stable heavy metal removal, providing new insights into the precipitation-dominated mechanism and the high-value utilization of medicinal plant residues.

Sugar production generates high-strength wastewater that poses a persistent threat to aquatic ecosystems, particularly in water-scarce regions. While wastewater treatment plants (WWTPs) are deployed to mitigate this impact, their performance is traditionally evaluated through pollutant removal efficiency, a metric that can mask the significant residual environmental pressure of the final effluent. This study employs the grey water footprint (GWF) to conduct a holistic, five-year (2021-2025) assessment of a sugar production facility in Isfahan, Iran, quantifying the volume of freshwater required to assimilate the pollutant load from both raw and treated wastewater. The analysis of raw wastewater revealed an exceptionally high pollution load, culminating in a Nitrate-dominated GWF of 167.3 m³ per ton of sugar produced. Following treatment via an upflow anaerobic sludge blanket (UASB) system, the effluent was monitored for key pollutants (BOD, COD, Nitrate, Phosphate). Diagnostic ratio, Principal Component Analysis (PCA), and a 95% confidence interval uncertainty analysis collectively and unequivocally identified Nitrate as the most unstable and critical parameter, consistently dictating the annual GWF. The treatment process achieved a substantial reduction, lowering the average GWF to 1.4 m³/ton, a decrease of over 99%. It was demonstrated that the GWF provides a more accurate and environmentally relevant benchmark than removal percentages alone, transforming the perception of treatment efficacy. The findings underscore the imperative to optimize treatment trains for robust Nitrate removal and to integrate GWF metrics into regulatory frameworks for sustainable water resource management in the sugar industry and analogous sectors.

Small reservoirs are under-researched despite their critical role in rural water supply, particularly regarding spatio-temporal variability and livestock-specific health thresholds. Most regional studies focus on water quality for human consumption not livestock, hence, this study, which aimed to assess physicochemical properties of the Makoye Reservoir and evaluate their implications on livestock using water samples collected during the 2023/24 rainy season through stratified random sampling, where sections of the reservoir were divided into strata and sampling points selected. Laboratory analyses included total suspended solids (TSS), turbidity, pH, nutrients (nitrates and phosphates), major ions (sodium, calcium, magnesium, and sulphates), and heavy metals (iron, lead, cadmium, and copper). Spatial heterogeneity was mapped using Inverse Distance Weighting interpolation in ArcGIS 10.2, having been the freely accessible version. Results showed that pH, nitrates, conductivity, sodium, and sulphates largely conformed to FAO thresholds, indicating generally acceptable seasonal quality. Phosphate averaged 0.48 mg/L, nearly five times the FAO maximum of 0.1 mg/L, raising concerns about eutrophication and reproductive health. Iron averaged 4.82 mg/L, over sixteen times the 0.3 mg/L limit. TSS averaged 2885.9 mg/L, almost three times the recommended 1000 mg/L, contributing to high turbidity and reduced palatability. Lead and cadmium were negligible, suggesting minimal industrial impact. Spatial analysis revealed nitrate hotspots in the northwest linked to agricultural runoff, sulphate peaks centrally associated with mineral dissolution, elevated iron near shorelines, and peripheral increases in calcium, magnesium, and sodium due to shoreline grazing. Although most parameters met FAO guidelines, critically high phosphates, iron, and suspended sediments pose risks to livestock health and reservoir ecology. Integrated livestock water quality needs assessment model, erosion control, improved manure management, and regular livestock-focused monitoring are recommended. The study suggests a novel water quality monitoring framework for livestock.

Groundwater resources in rapidly urbanizing Himalayan cities are under severe stress due to overexploitation and contamination, a situation exacerbated by seismic activity, which disrupts aquifer integrity. This study presents an integrated framework for assessing groundwater potential and quality in Muzaffarabad, Pakistan, a city traversed by active faults, including the Muzaffarabad Thrust Fault and Jhelum Strike-Slip Fault. We combined geospatial, geophysical, and hydrochemical techniques to map resources and identify contamination pathways. Groundwater potential zones (GWPZs) were mapped using Analytical Hierarchy Process (AHP) and Random Forest (RF) models, with the RF model demonstrating superior predictive accuracy (AUC = 0.86). Vertical Electrical Sounding (VES) surveys within these zones revealed aquifer thicknesses ranging from 35-100 m and transmissivity values of 0.8-16,948 m²/day, validating the north-central and southwestern regions as priority zones. Notably, hydrochemical analysis revealed that while 57% of samples exhibited 'excellent' chemical quality (Ca²⁺-Mg²⁺-HCO₃⁻ facies), 52% were contaminated with Total Coliforms. Spatial analysis directly links this pervasive biological contamination to inadequate sanitation and, more significantly, to aquifer vulnerability enhanced by tectonic faults, which act as proven conduits for surface pollutants. This study provides quantitative evidence that tectonic activity in the Himalayan foothills is a primary control on groundwater contamination risk. The integrated methodology offers a replicable framework for sustainable water management in tectonically active urban areas globally.

Biochar is an effective adsorbent for antibiotics, but the impacts and mechanisms of biochar on oilseed rape (Brassica napus L.) under antibiotics stress are not yet clear. Therefore, we investigated root morphology, photosynthesis, root antioxidant systems, and root transcriptome treated by sulfamethazine (K) and sulfamethazine + Platanus orientalis L. leaf biochar (TK). The results indicated that the sulfamethazine stress decreased root length, surface area, volume, and diameter by 14.06%, 35.91%, 36.71%, and 19.47%, respectively, compared with CK because net photosynthetic rate was decreased by 35.54% and reactive oxygen species (H₂O₂ and O₂^-) balance was damaged. However application of the biochar increased net photosynthetic rate (38.84%), and further enhanced activity of catalase (27.48%) to decrease reactive oxygen species content, thereby promoting root growth, especially root length significantly increased by 29.55%. Transcriptomic analysis revealed that biochar induced root growth and reactive oxygen species balance of oilseed rape under sulfamethazine stress through enhancing the expression of genes related to the cell wall and auxin biosynthesis such as auxin response factor, auxin/indole-3-acetic acid, small auxin-up RNA, Gretchen-Hagen 3, and dormancy/auxin associated protein. Our study provides insights for the biochar improving oilseed rape growth under sulfamethazine stress, and can promote the remediation of antibiotic-contaminated farmland soil, agricultural production.

Fuel combustion in households leads to the generation of ashes, and the effect of such wastes on plant growth and Al and Zn uptake is poorly understood. Therefore, in this study, two soils (A-1: sandy loam and B-1: sandy soils) were amended with two ashes (10 %) after coal-wood co-combustion in households (ASH1; ASH2). The control and ash-amended control soils were subjected to a pot experiment where Raphanus sativus and Spinacia oleracea were cultivated. The mobilization of Al and Zn in soils was assessed in the leaching experiment with Pseudomonas fluorescens. The study reveals that ashes do not significantly affect the biomass of Raphanus sativus. In turn, both ashes increase the biomass of Spinacia oleracea regardless of the soil used (up to 3049 mg DW in biomass of leaves in the ash-amended soil compared to the control soil where the biomass is 1180 mg DW). The highest Al translocation factor (TF) is noted for Raphanus sativus in the ash-amended soil (0.84; with ASH1), whereas for Zn, for Spinacia oleracea (3.03) also in soil amended with ASH1. The Al and Zn mobilization with Pseudomonas fluorescens is higher in soils from all treatments compared to the sterile growth medium as the control. Furthermore, bacteria can mobilize Al in the short term in ash-amended soil from the river valley (up to 1.18 % in the ash-amended soil) indicating that even the long-term mobilization of Al and Zn by the bacteria is possible. Therefore, household ashes are not recommended for soil amelioration and fertilization.

The study examined natural radionuclide levels in edible muscles of cephalopod species consumed in Kerala. Uranium (²³⁸U) concentrations ranged from 1.14 ± 0.06 to 1.72 ± 0.07 Bq kg^-1, while thorium (²³²Th) levels were between 0.08 ± 0.02 and 0.66 ± 0.04 Bq kg^-1. Polonium (²¹⁰Po) showed higher concentrations, ranging from 4.7 ± 0.9 to 27.2 ± 3.3 Bq kg^-1, and lead (²¹⁰Pb) levels varied from 3.8 ± 0.9 to 24.6 ± 6.8 Bq kg^-1. Squids, being pelagic, accumulated higher amounts of ²³⁸U and ²¹⁰Po, whereas cuttlefishes, being benthic, showed greater levels of ²³²Th and ²¹⁰Pb. Statistical analysis revealed significant differences in radionuclide concentrations among and within cephalopod species, influenced by habitat and taxonomy (p < 0.05). The annual committed effective dose (ACED) for coastal residents consuming these cephalopods was assessed. ²¹⁰Po was the main contributor to radiation dose, comprising over 80% of the total dose from all radioisotopes analyzed. Despite this significant contribution, the study concluded that health risks from consuming these cephalopods were within acceptable safety limits.