Environmental Geochemistry and Health最新文献

The groundwater salinization problem in the south bank of the Yellow River irrigation area is severe, restricting the sustainability of groundwater resources. However, the groundwater salinization formation mechanism is unclear. Accordingly, this study analyzed the chemical characteristics and salinization mechanism of groundwater based on hydrochemical analyses (self-organizing maps, SOM), isotope analyses (δ¹⁸O and δD), and quantitative models (Rayleigh distillation model), as well as evaluating the potential health risks of fluoride. The results indicated that surface water and groundwater in the study area had high salinity and weak alkalinity, with the fluoride and total nitrogen (TN) content exceeding Grade III water standards. Additionally, only 42% of the water samples were suitable for drinking, with nitrogen sources being the main cause of water quality deterioration. Around half of the samples were unsuitable for irrigation. The spatial and temporal distribution of total dissolved solids (TDS) in the irrigation area was influenced by autumn irrigation. Overall, groundwater salinization was primarily attributed to evaporite dissolution, cation exchange, silicate weathering, and human inputs. Evaporation was not the main influencing factor. In addition, the non-carcinogenic risk of fluoride in the water body decreased as follows: infants > children > adult females > adult males. The results of this study deepen understanding of the relationship between changes in groundwater quality and the ecological environment in semi-arid inland areas, thereby promoting the rational utilization and scientific management of groundwater resources in the irrigation area.

Rare earth elements (REEs) are increasingly recognized as significant environmental pollutants due to their environmental persistence, bioaccumulation, and chronic toxicity. This study assessed REEs pollution in soil, water, and vegetables in an ion-adsorption rare earth mining area in Ganzhou, and evaluated the associated health risks to the local population. Results indicated that the REEs content in soil ranged from 168.58 to 1915.68 mg/kg, with an average of 546.71 mg/kg, substantially surpassing the background level for Jiangxi Province (243.4 mg/kg) and the national average (197.3 mg/kg). Vegetables displayed an average REEs content of 23.17 mg/kg in fresh weight, far exceeding the hygiene standard of 0.7 mg/kg. Water samples contained REEs at a concentration of 4.09 μg/L. The estimated daily intake (EDI) of REEs from vegetables exceeded the threshold for subclinical damage, posing potential health risks, particularly for children and adolescents. Further analysis of the adjusted average daily intake (ADI) and non-carcinogenic risk suggested that while most vegetable consumption remains within safe threshold, the intake of REEs from high-risk vegetables such as pakchoi should be limited. Overall, carcinogenic risks associated with lifetime cancer risk (LCR) model for REEs exposure through vegetables and water were found to be low in this area.

In attention to the Sustainable Development Goal 6, the quality evaluation of water resources in Mexico is limited compared to other regions. This study provided new data from Oriental Basin, an important socio-economic region with up to 20% population growth over the last decade by assessing groundwater from the Libres-Oriental aquifer (Ca-Mg-HCO₃ facies; F^-: 2.5-9.9 mg/L; NO₃^-: up to 75.3 mg/L) and water from the Totolcingo Lake (Na-Cl facies; F^-: 12.7-13.2 mg/L; NO₃^-: < 0.75 mg/L). Fluoride content grouped about 80% groundwater samples as promotor of dental and skeletal fluorosis. Nitrate Pollution Index suggested moderate pollution in 20% and very significant pollution in 10% groundwater samples. Possible exposure of older adults and elderly pregnant women to fluorosis from all the groundwater samples (Hazard Quotient > 1) from the Oriental Basin and 55% of them might also be causing fluorosis in infants suggest a potential health risk hotspot in the eastern-central Mexico. Even though all the groundwater samples did not contain enough NO₃^- to cause methemoglobinemia, their boiling for drinking could enhance nitrate content beyond the WHO limit. Thus, the mitigation techniques might diminish the health risks in consuming population.

Petroleum contaminated soil (PCS) has complex properties and compositions, which seriously endangers the environment and is difficult to treat. In this study, a new method for the remediation of PCS using MgO as remediation agent was proposed. Meanwhile, the mechanism of PCS remediation was revealed by various characterization methods. The study found that MgO was effective in remediating PCS. The results of PCS remediation showed that the residual oil rate of PCS decreased from 2.62 to 1.37%, and the absolute removal rate of oil in PCS after remediation was 37.3% under the optimum remediation conditions. The mechanism research indicated that the prepared MgO had large specific surface area, high hydration activity and strong adsorption with the conditions of calcination temperature of 650°C, calcination time of 120 min and heating rate of 10°C/min. In the remediation process of PCS, MgO was tightly adsorbed on the surface of PCS particles, and the hydration reaction occurred rapidly after contact with water to form Mg(OH)₂. Mg(OH)₂ could effectively encapsulate soil particles firmly, ensuring the stability of PCS, thereby achieving the effective remediation of PCS. This study provided a new method for the remediation of low-concentration PCS, and had important scientific significance for the future research on the advanced treatment of low-concentration PCS.

Soda saline-alkali soils pose significant challenges to agricultural productivity due to high pH and excessive sodium content. This study investigated the removal of excess salts in soda saline-alkali soil through electrochemical treatment (ECT). Traditional ECT often led to uneven soil pH distribution, with acidic conditions near the anode and alkaline conditions near the cathode, which limited its effectiveness for soil improvement. We explored the impact of conditioning the catholyte pH coupled with approaching anode electrochemical treatment (AA-ECT) on soil pH distribution and the removal of soluble sodium ions in soda saline-alkali soil. The results demonstrated that AA-ECT was less effective than fixed anode electrochemical treatment (FA-ECT) in regulating soil pH, achieving a relatively uniform pH range of 7.31-8.44. Adding acetic acid further improved pH uniformity, narrowing the range to 7.32-8.02. Moreover, all experimental groups exhibited high removal of soluble sodium ions efficiency, and the acetic acid coupled with AA-ECT achieved an average removal efficiency of 91.90%. Notably, the soil was successfully transformed from severely alkali soil (exchangeable sodium percentage (ESP) > 61%) to non-alkali soil (ESP < 14%). Additionally, the AA-ECT groups showed lower energy consumption than the FA-ECT groups. These findings highlighted that conditioning the catholyte pH coupled with AA-ECT was a highly effective strategy for improving soda saline-alkali soils, offering a sustainable solution for soil remediation and agricultural productivity enhancement.

Submarine Groundwater Discharge (SGD) has a global impact, affecting coastal aquifers, the freshwater environment, and contributing to coastal development. The present study investigates the impact of Submarine Groundwater Discharge (SGD) on groundwater geochemistry along the coast from Chettikulam to Kolachel in Southern India, with an emphasis on regional changes pre and post monsoons in the years 2023-2024. A total of 80 groundwater samples (40 from both monsoons) were analyzed using hydrochemical plots such as Piper, Wilcox, Gibbs, and Hydrochemical Facies Evolution Diagrams (HFE-D), along with AquaChem software and spatial mapping techniques. Hydrogeochemical analysis reveals significant seawater intrusion during the pre-monsoon period, with 48% of groundwater samples categorized under the Mixed Ca-Mg-Cl facies and 30% under the Ca-Cl facies, leading to elevated salinity, total dissolved solids (TDS), chloride, and sulfate concentrations. In contrast, post-monsoon conditions demonstrate improved water quality due to monsoonal recharge, with 55% of samples in the mixed Ca-Mg-Cl facies but exhibiting reduced salinity. Water Quality Index (WQI) analysis shows an increase in 'Excellent' water samples from 22.5% pre-monsoon to 37.5% post-monsoon. The Wilcox diagram highlights a reduction in salinity hazards, improving groundwater suitability for irrigation. The Seawater Mixing Index (SMI) indicates the seawater intrusion in coastal zones, although monsoonal dilution mitigates its effects. Seasonal variation in hydrochemical facies reveals a decrease in the freshening phase from 60% pre-monsoon to 45% post-monsoon, alongside an expansion of the intrusion phase from 40 to 55%. The study underscores the need for ongoing groundwater monitoring and effective water management strategies to sustainable coastal aquifers impacted by Submarine Groundwater Discharge (SGD).

Microplastics (MPs), as a global environmental issue, have unclear impacts on agricultural ecosystems. Cotton, as a major agricultural crop in Xinjiang, requires plastic film covering to ensure its yield. The widespread use of plastic film (commonly made of polyethylene) in cotton cultivation has led to significant concerns about microplastic pollution in cotton fields. However, there is limited research on the effects of MPs on cotton growth and cotton field ecosystems. This study investigates the effects of different concentrations and particle sizes of polyethylene microplastics (PE-MPs) on the physiological changes in cotton plants and the physicochemical properties of the soil. The results show that cotton seedling growth was inhibited in all treatment groups, with a clear dose-dependent effect. In the 200 μm^-1wt% treatment group, the cotton seedlings' antioxidant system experienced severe stress, reflected by significant increases in malondialdehyde and total soluble proteins by 58.95% and 94.29%, respectively, which suppressed plant growth and caused a significant reduction in cotton plant height by 41.95%. Additionally, the inhibition of leaf photosynthesis by PE-MPs was more pronounced as the particle size decreased. Under higher concentrations (1wt%, 3wt%), the transpiration rate (Tr) and stomatal conductance (Gs) were significantly suppressed. In the 2 μm^-1wt% treatment group, Gs and Tr decreased significantly by 44.35% and 36.21%, respectively, compared to the control group. Furthermore, the addition of PE-MPs significantly increased the organic matter and available nitrogen content in the soil, with a dose-dependent effect. At the highest concentration (3wt%), the available nitrogen content increased by 1.78, 1.86, and 1.68 times, respectively, compared to the control group. These findings demonstrate the impact of PE-MPs on cotton seedlings and soil properties, providing strong evidence for the ecological risks of MPs in plastic film-covered agricultural fields.

Despite the consensus on the importance of considering the bioavailability of metal(loid)s by measuring their bioaccessibility when assessing exposure, integrating these parameters into risk calculations often involves proprietary approaches that lack adequate justification. This is the case with the in vitro unified bioaccessibility method (UBM), which is widely used in Europe to assess the bioaccessibility of metal(loid)s in the event of soil ingestion. This study proposes a comprehensive operational approach that incorporates bioaccessibility to refine human exposure and risk assessments. A pilot study of 45 Pb-contaminated soil samples collected in and around Paris highlighted the importance of carefully following soil preparation protocols. Specifically, sieving the soil to 250 µm without mechanical milling is recommended for determining both bioaccessible and total concentrations. A simplified test using dilute hydrochloric acid can predict the bioaccessibility of metal(loid)s in first-tier screening. This affordable, single-extraction method is easy to use in analytical laboratories and is both fast and reproducible. For second-tier validation studies, the UBM protocol should be applied to a limited number of samples. With the new approach, the relative bioavailability can be directly calculated using an in vivo/in vitro equation in the stomach compartment, thus, enabling UBM validation. The results of the pilot study demonstrated that to refine exposure assessments, adjusting chronic daily intake using relative bioavailability data was more effective than were classical approaches based on total concentrations. This method offers a promising perspective for stakeholders in managing polluted sites and soils.

This study investigated the role of Al and As fate during the transformation process of ferrihydrite influenced by different pH values under oxic conditions. The results indicate that the Al doping greatly enhanced the transformation of ferrihydrite (Fh) to Al-substituted goethite at all acidic or alkaline pH values under oxic conditions by promoting the incongruent dissolution and reprecipitation reactions of Al-substituted ferrihydrite (AlFh). Under acidic conditions, the preferential dissolution of structural Fe (4.73 mg/L) from AlFh occurs, whereas under alkaline conditions, the preferential dissolution of structural Al (1.25 mg/L) takes place. In contrast, under neutral conditions, the low solubility of Fh and AlFh induces the significant particle assembly, with Fe/Al minerals primarily transforming into goethite through oriented aggregation. As predominantly remains in an adsorbed state at all pH values during the transformation of Fh and AlFh, with the highest proportion of adsorbed As (86.9-96.7%) observed under neutral conditions. During the aging process, the adsorbed As gradually transforms into non-extractable As, and the changes in As speciation within Fe/Al minerals are closely coupled with the transformation of AlFh and Fh. Under alkaline and acidic conditions, the proportion of non-extractable As in the transformation products of Fh and AlFh increases by 14.02-19.72% and 12.27-16.28%, respectively, while under neutral conditions, it increases only by 12-13.02%. Therefore, regulating soil pH can partially modify As speciation and mitigate its environmental impact by altering the mineral transformation process. The results of this study facilitate better understanding of the role of Al substitution in the transformation of Fh and the cycling of As in the environment.

The preservation of groundwater quality is essential for maintaining the integrity of the water ecological cycle. The preservation of groundwater quality is crucial for sustaining the integrity of the water ecological cycle. Nitrate (NO₃^-) has emerged as a pervasive contaminant in groundwater, attracting significant research attention due to its extensive distribution and the potential environmental consequences it poses. The primary sources of NO₃^- pollution include soil organic nitrogen, atmospheric nitrogen deposition, domestic sewage, industrial wastewater, landfill leachate, as well as organic and inorganic nitrogen fertilizers and manure. A comprehensive understanding of these sources is imperative for devising effective strategies to mitigate NO₃^- contamination. Technologies for tracing NO₃^--polluted groundwater include hydrochemical analysis, nitrogen and oxygen isotope techniques, microbial tracers, and numerical simulations. Quantitative isotope analysis frequently necessitates the application of mathematical models such as IsoSource, IsoError, IsoConc, MixSIR, SIAR, and MixSIAR to deduce the origins of pollution. This study provides a summary of the application scenarios, as well as the strengths and limitations of these models. In terms of remediation, pump and treat and permeable reactive barrier are predominant technologies currently employed. These approaches are designed to remove or reduce NO₃^- concentrations in groundwater, thereby restoring its quality. The study offers a systematic examination of NO₃^- pollution, encompassing its origins, detection methodologies, and remediation approaches, highlighting the role of numerical simulations and integrating multidisciplinary knowledge. Additionally, this review delves into technological advancements and future trends concerning the detection and treatment of NO₃^- pollution in groundwater. It proposes methods to control the spread of pollution and acts as a guide for identifying and preventing pollution sources.