Atmospheric particulate samples collected on quartz-fibre filters can be difficult to examine stereomicroscopically because dense dark and granular residues obscure potential target particles. This exploratory study qualitatively screened five pretreatment configurations intended to improve visualization of morphologically suspected atmospheric microplastics. One PM10-loaded quartz filter from a single 24-h sampling event was divided into eight approximately equal sections; five sections were allocated individually, one per method, without independent replication. All sections underwent static digestion in 100 mL of 30
Plastics constitute a significant source of chemical additives that can migrate into aquatic environments during use and the degradation of polymer materials. The aim of this study was to determine the release dynamics of selected plasticizers (phthalates and bis(2-ethylhexyl) adipate) and phenolic compounds (alkylphenols and bisphenol A) from single-use products made from different types of plastics. The study was conducted under laboratory conditions using leaching tests in distilled water over three time intervals (7, 30, and 60 days). The analyzed materials were classified into seven groups according to recycling codes (polyethylene terephthalate (PET), high-density polyethylene (HDPE), polyvinyl chloride (PVC), low-density polyethylene (LDPE), polypropylene (PP), polystyrene (PS), other (OTHER)). Concentrations were determined using gas chromatography coupled with mass spectrometry (GC–MS). The results showed significant variation in the amounts of released additives depending on the type of polymer and the duration of the test. The highest concentrations of phthalates and bis(2-ethylhexyl) adipate were observed in products made of HDPE and PVC, whereas for alkylphenols and bisphenol A, PVC was the dominant polymer exhibiting the highest concentrations. Temporal variability in the concentrations of organic compounds leached from the polymer matrix was observed, most likely due to the experimental design and the non-linear nature of the leaching process. The obtained results indicate that single-use polymer products can serve as a potential source of organic contaminants in aquatic environments, and that the migration of additives is influenced by multiple material and environmental factors.
Reliable effluent Chemical Oxygen Demand (COD) prediction is critical for stable operation and pollution control of municipal wastewater treatment systems. However, conventional forecasting methods are limited by feature redundancy, data imbalance and weak cross-model robustness. This study develops an integrated machine learning framework integrating feature screening, time-series data augmentation, multi-model evaluation and interpretability analysis. Based on 1,186 consecutive daily datasets from a municipal wastewater treatment plant in Yunnan, Pearson correlation analysis and Grey Relational Analysis (GRA) jointly screened six key variables: Mixed Liquor Suspended Solids (MLSS), Sludge Volume (SV), pH, influent Total Phosphorus (TP), influent COD and influent Biochemical Oxygen Demand (BOD5). A time-series-based Synthetic Minority Oversampling Technique (SMOTE) was adopted to optimize sparse high-COD samples and avoid temporal inconsistency and data leakage. Among 16 typical models, the ExtraTrees model performed best, with a test R2 of 0.839 and Mean Absolute Error (MAE) of 1.79 mg/L. Hapley Additive exPlanations (SHAP) analysis proved MLSS as the core factor affecting effluent COD, followed by SV, pH and influent parameters. Effluent COD is co-regulated by biomass, sludge settleability, reactor environment and external load. This framework offers accurate, interpretable references for wastewater treatment plants in effluent prediction, early warning and intelligent management.
Groundwater in the Maadher Hodna aquifer (Algeria) was assessed using an integrated approach combining hydrochemical analysis, pollution indices, GIS mapping, and machine-learning techniques to distinguish natural hydrochemical controls from nitrate-related anthropogenic impacts. Electrical conductivity exceeded the drinking-water guideline in 93.33 R^2=0.23± 0.30 ; two folds yielded negative R^2 values), suggesting that nitrate variability is not adequately explained by background hydrochemistry alone. The support vector machine (SVM) efficiently reproduced PIG-based groundwater-quality classes from the hydrochemical variables used in the PIG calculation, demonstrating potential for automated screening rather than an independent predictive relationship. Overall, the integrated framework identifies widespread mineralization and spatially heterogeneous nitrate contamination and provides a basis for targeted groundwater monitoring and agricultural pollution management.
Hydrodynamic disturbance regulates phosphorus (P) release and retention in reservoir sediments, but the response varies spatially among cascade reservoirs. We investigated Xuanmiaoguan and Tianfumiao reservoirs using field measurements, P fractionation, and 48-h adsorption-release experiments conducted under static, low- and high-disturbance conditions. Contrasting source-sink patterns were observed between the two reservoirs. The deep mid-reservoir zone acted as a P source in Xuanmiaoguan, where porewater PO4-P was 3.89 times that in the overlying water, whereas the tail acted as a sink. The tail was the main source in Tianfumiao, whereas the head acted as a sink. Distinct hydrodynamic responses were further observed between the two reservoirs. The highest cumulative release reached 94.5 mg kg⁻1 under sustained low disturbance in Xuanmiaoguan source sediment, indicating prolonged P mobilization, whereas Tianfumiao source sediment showed a more sustained release pattern. Phosphorus capture was enhanced differently in the two sink zones, with the highest adsorption reaching 122 mg kg⁻1 under low disturbance in Tianfumiao. Phosphorus fractionation further indicated that disturbance-driven mobilization was accompanied by redistribution from inorganic P to organic P. These results demonstrate that hydrodynamic forcing regulates phosphorus source-sink differentiation through reservoir-specific effects on release, adsorption, and fraction transformation, providing a basis for site-specific hydrodynamic management.
