Water, Air, & Soil Pollution最新文献

Extracellular polymeric substances (EPS) are a collection of organic molecules from microbial metabolism, secreted outside the cell to counteract effects of harsh environment, a process that has enabled the application of the biopolymer for wastewater treatment. Reduction in concentration of lead II (Pb²⁺) and chromium VI (Cr⁶⁺) together with other physicochemical parameters from tannery wastewater by EPS from Penicillium expansum was studied. The maximum removal of Pb²⁺ and Cr⁶⁺ were 23.13% and 17.83% respectively under optimized removal conditions of 180 rpm agitation, 90 mg/L EPS concentration, 5.0 pH at  40 °C using a 2-h residence time. However, this low percentage removal of Pb²⁺ and Cr⁶⁺ in the tannery wastewater called for more batches of removal process under optimized conditions. After subjecting the EPS to four batches of removal process, 100% and 89.75% removal of Pb²⁺ and Cr⁶⁺ respectively were achieved in less than 8 h. Based on this, FTIR Analyses showed frequency shifts in alkenyl (C = C), hydroxyl (OH) and carbonyl (C = O) functional groups, and molecular overlapping in the EPS was observed on scanning electron micrograph. Physicochemical parameters in the tannery wastewater were significantly (p < 0.05) reduced by 50% or more with the exception of pH after the duration of the biosorption process. The findings in this study showed that EPS produced by P. expansum could significantly (p < 0.05) decrease the concentrations of Pb²⁺, Cr⁶⁺ and other heavy metals as well as other tannery wastewater physicochemical properties that contributed to its polluting effect.

The prediction of methane (CH₄) concentration is important for pig farming due to its environmental impact on pigs and farm workers. This study examined the utilization of machine learning algorithms, specifically multiple linear regression (MLR), XGBoost regression (XGB), and random forest regression (RFR), to predict CH₄ concentrations in pig barns during the growing-finishing stage of pigs. The dataset included five key input biophysical variables: feed intake (FI), pig mass (MP), carbon dioxide (CO₂) levels, temperature (T), and relative humidity (RH). Data was collected from three experimental pig barns during 2022 and 2023 to train and test the machine learning models. Among the three machine learning models, the RFR consistently outperformed both MLR and XGB in predicting CH₄ concentrations. The results demonstrated better performance by the RFR model in testing (R² > 0.81), with improvements in R² of up to 1.92% and 10.46%, as well as decreases in RMSE of up to 5.74% and 20.51%, compared to the XGB and MLR across the three input datasets. In terms of stability, MLR exhibited the maximum stability, followed by RFR and XGB. Sensitivity analysis found FI to be the most influential input variable for CH₄ concentration prediction, with the impact ranking being FI > MP > CO₂ > T > RH. This study emphasized the potential of machine learning models, particularly RFR, in predicting CH₄ concentrations using relevant input variables. These findings enhance understanding of CH₄ concentration, providing useful insights into pig production and environmental management.

As freshwater resources become increasingly scarce, safe drinking water is critical to public health. However, emergent pollutants and pathogenic microorganisms threaten this goal, posing direct and indirect water quality risks. Photocatalysis offers a promising alternative disinfection strategy, overcoming many limitations of conventional methods by generating reactive oxygen species (ROS) capable of effectively deactivating microbial contaminants through targeted redox reactions. This review explores the photocatalytic disinfection process, detailing microbial inactivation mechanisms, and provides a comparative analysis of commonly used photocatalysts and their composites. Sources of microbial contamination, including bacteria, viruses, algae, fungi, and protozoa, are discussed to contextualize the challenges faced in water treatment. Key operational parameters influencing photocatalytic efficiency and an overview of practical bioreactor types optimized for varied disinfection needs are also addressed. This comprehensive review highlights the advancements and potential of photocatalytic bioreactors in safeguarding water quality and expanding accessible, efficient, and eco-friendly disinfection technologies.

The Reghaïa Nature Reserve (Algeria) comprises a freshwater lake surrounded by natural soils covered by spontaneous vegetation with a habitat for wildlife. It is exposed to 3 mains sources of pollution i.e. an industrial zone, agricultural lands and the urban area. Abnormal high levels of metallic trace elements (MTEs) have been already reported in lake’s water and natural topsoil. In the present study, we explore the tolerance and phytoremediation capacity of Oxalis pes-caprae L., growing spontaneously on Reghaïa lake’s bank, toward Pb, Zn and Cd, the 3 main metal pollutants from anthropogenic activities. Sampling was carried out over 4 months, for Oxalis pes-caprae L. plants and rhizosphere soils, harvested in 3 sites along a gradient of proximity to lake’s water. Firstly, we estimated the degree of contamination of the sampled sites by Pb, Zn and Cd and we determined soils parameters which influence metals distribution in soil and their absorption by O. pes-caprae L. roots. Secondly, we examined the distribution and the accumulation of Pb, Zn and Cd within O. pes-caprae shoots and roots. The results revealed that Pb and Cd were the main soil pollutants and that O. pes-caprae L. adopted different remediation strategies such as an exclusion strategy for Pb in soil and a phytoextraction strategy for Cd.

Triclosan (TCS) is widely used in personal care products due to its effective antibacterial properties. However, the increasing frequency of TCS detection in global surface waters, particularly following the heightened use of disinfectants during the COVID- 19 pandemic, underscored the need for careful environmental risk assessment. In this study, we conducted ecological toxicity assays using the model organism Caenorhabditis elegans to investigate the potential risks of environmentally relevant concentrations of TCS. After 72 h of exposure, specific reproductive toxicity, including a decrease in eggs in utero at concentrations ranging from 0.1 to 5 μg L⁻¹ was observed. The predicted no-effect concentration (PNEC) was determined based on a 10% inhibition of egg formation using the Hill and Weibull models. At lower concentrations, TCS inhibited total brood size in C. elegans and increased intracellular ROS levels and sod- 3 antioxidant gene expression. The reproductive risk of TCS in urban freshwater environments was further assessed using predicted environmental concentrations (PEC) from 2019 to 2022 and the PNEC simulated in this study. Risk quotient (RQ) and exceedance risk (ER) analyses indicated a high reproductive risk of TCS (RQ > 1 or inhibition > 10% at ER = 0.5) in urban rivers and lakes, particularly in the post-pandemic period. Given the global concern over the potential hazards of TCS, our findings contributed to understanding its environmental risks in urban freshwater systems and provided a basis for regulatory authorities to develop appropriate control measures and management strategies.

Spring water is one the important source of fresh water in the Himalayan region which is used for drinking, irrigation, and industrial purposes. With the unprecedential rise in the urbanization and industrialization, has posed severe threats to spring water resources. The water quality of springs has severely deteriorated owing to the changes in land use patterns. In the present study, the physiochemical parameters of the spring water of intermountain Doon valley, present at the eastern Himalayan region were assessed in order to simultaneously understand the hydrogeochemistry of the region and the factors controlling the ion chemistry of water. In total nine water samples were collected from three different water springs during three different seasons and were different water quality parameters were analyzed viz. temperature, pH, electrical conductivity (EC), total dissolved solids (TDS), bicarbonate (HCO₃⁻), sulphate (SO₄²⁻), chloride (Cl⁻), nitrate (NO₃⁻), and fluoride (F⁻) total hardness (TH), calcium (Ca²⁺), magnesium (Mg²⁺), sodium (Na⁺) and potassium (K⁺). The heavy metal analysis (for Cu, Pb, Ni, Cr and Cd) for all the three seasons was found to be below the BIS threshold for drinking water quality. The total coliform and E. coli tests were conducted and was found to above the BIS standard's permissible limits. The Water Quality Index (WQI) was evaluated to check the suitability of water for drinking purposes and as per WQI index water and was found to be under the good category for drinking purposes. The spring water have fallen under the excellent to good category for irrigation purposes. The high ratio of Ca²⁺ + Mg²⁺ / Na⁺ + K⁺ and a low ratio of Na⁺ + K⁺ /TZ⁺ indicated the dominance of carbonate weathering in the studied area. The piper trilinear diagram indicated the Ca²⁺-Mg²⁺-HCO₃ and Ca²⁺-Mg²⁺–HCO₃^– -SO₄²⁻ were dominant hydro-chemical facies in the study area.

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Revegetation is widely recognized as a promising strategy for the large-scale bauxite residue management and disposal. However, its potential ecotoxicological risks, particularly the ecotoxicity of treated bauxite residue leachate on aquatic organisms, remain largely unknown. This study assessed the effects of exposure to bauxite residue leachates from short-term revegetation on oxidative stress and DNA damage in zebrafish (Danio rerio) tissues. The results revealed significant variations in the activities or levels of superoxide dismutase (SOD), catalase (CAT), acetylcholinesterase (AChE), malondialdehyde (MDA), and 8-hydroxydeoxyguanosine (8-OHdG) in zebrafish liver, brain, gill, and muscle tissues after 7, 14, 21, and 28 days of exposure to bauxite residue leachates. The integrated biomarker response (IBR) index indicated that leachate from treated residue exhibited greater toxicity to the liver, gills, and muscle compared to untreated residue, whereas brain tissue exhibited the opposite trend. Correlation analysis revealed significant positive and negative correlations between pH, EC, Al, Na, As, and V in leachates and oxidative stress/DNA damage biomarkers in zebrafish tissues. Despite the neutral pH (7.44 ± 0.26) and low concentrations of Al (0.67 ± 0.01 mg·L⁻¹), As (4.65 ± 0.20 mg·L⁻¹), and V (0.01 ± 0.00 mg·L⁻¹) in the treated residue leachate, the relatively higher Na concentration (22.33 ± 3.61 mg·L⁻¹) and other contaminants introduced by amendments and bauxite residue likely played a key role in inducing oxidative stress and DNA damage in zebrafish tissues. These findings highlight the importance of carefully selecting amendments for revegetation to support plant establishment while minimizing secondary contamination risks. This study provides valuable insights into the environmental risks of short-term bauxite residue revegetation, contributing to the development of more effective and sustainable revegetation strategies.

This study introduces an efficient and environmentally friendly approach by utilizing synthesized ZnO nanoparticles to degrade pharmaceutical contaminants. The structural and optical properties of the nanoparticles were extensively characterized using Fluorescence spectrometry, UV–VIS spectroscopy, FTIR spectroscopy, particle size analysis, Zeta potential, PXRD, FE-SEM, and EDAX techniques. The photocatalytic degradation of paracetamol (PARA) and diclofenac (DCF) was successfully achieved using ZnO in combination with Fenton’s reagent across a wide pH range (2.5, 7.0, and 10.5) and various light sources. Enhanced degradation efficiency was observed at lower pH levels (pH = 2.5) than at higher pH values (pH = 7.0 and 10.5) under all light sources tested. Notably, ZnO achieved complete degradation within 45 min under UV254 exposure at pH 2.5, outperforming other conditions tested. This research highlights the potential of ZnO photocatalysts and their functionalization to effectively mitigate the environmental impact of pharmaceutical pollutants.

Since municipal solid waste incineration fly ash (MSWI FA) contains a large amount of potentially toxic heavy metals that need to be safely treated before landfill, solidification/stabilization chemical stabilization method is one of the most commonly used methods for MSWI FA treatment. To investigate the effects of different inorganic and organic chelating agents on the solidification of heavy metals (such as Pb, Cd, etc.), immobilization, here we selected three inorganic chelating agents (Na₂S, NaH₂PO₄ and Na₃PO₄) and four organic chelating agents (thiourea, diethyl-mercaptan, DDTC and EDTA Na) for a comprehensive comparison of the heavy metal stabilization and immobilization performance. The leaching and BCR results indicate that under the same low addition conditions, diethyl-mercaptan containing double bond groups exhibits a better chelating effect on most heavy metals (such as Pb, Cd, Cr, Cu and etc.), and the addition of Na₂S can better increase the residual state ratio of Cd. Moreover, we further selected inorganic Na₂S and organic diethyl mercaptan for compounding and it was found that the content of cadmium and lead in the leaching product after the composite chelating agent NS-2 solidified the heavy metals was low, and the lead content was far below the safety threshold of the landfill standard of China (GB16889-2008), which can significantly save the cost of chemicals. This work can provide a reference for the selection and design of effective chelators for stabilizing toxic heavy metals.

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