Journal of contaminant hydrology最新文献

Microplastics (MPs) and antibiotics can enter groundwater through the interaction of soil and surface water, and MPs as carriers of antibiotics can promote the migration of antibiotics and thus generate more serious ecological risks. Therefore, this paper used experimental and molecular dynamics (MD) simulation methods to investigate the sorption between four common types of MPs in groundwater, namely polyamide (PA), polystyrene (PS), polyvinyl chloride (PVC), and polyethylene (PE), and oxytetracycline (OTC) with high detection rate in groundwater. Additionally, the impact of environmental factors on sorption was examined. The sorption kinetics of the four types of MPs followed the pseudo-second-order kinetics model, and the sorption isotherms of OTC on PA, PE, and PVC were highly linear, suggesting that the electrostatic interaction was the main sorption mechanism. Both experimental and simulation results indicated that PA had the highest affinity for OTC, due to the effect of the formation of hydrogen bonding between the amide groups of PA and OTC. The primary way pH affected sorption was by altering the form in which OTC exists. The effects of the representative substances of protein-like component (bovine serum albumin) and humus-like component (humic acid) in dissolved organic matter varied but were generally inhibitory. Ions could influence the sorption process by competitive sorption or forming complexes with the OTC.

Investigating the potential of novel data mining algorithms (DMAs) for modeling groundwater quality in coastal areas is an important requirement for groundwater resource management, especially in the coastal region of Bangladesh where groundwater is highly contaminated. In this work, the applicability of DMA, including Gaussian Process Regression (GPR), Bayesian Ridge Regression (BRR) and Artificial Neural Network (ANN), for predicting groundwater quality in coastal areas was investigated. The optuna-based optimized hyperparameter is proposed to improve the accuracy of the models, including optuna-GPR and optuna-BRR as benchmark models. Combined cross-validation (CV) and bootstrapping (B) methods were used to build six predictive models. The entropy-based coastal groundwater quality index (ECWQI) was converted into a normalized index (ECWQIn), which was divided into five classes from very poor to excellent. The self-organizing map (SOM), spatial autocorrelation and fuzzy logic model were used to identify spatial groundwater quality patterns based on 12 physicochemical variables collected from 67 groundwater wells. The SOM analysis identified four distinct spatial patterns, including EC-TDS-Cl^-, MgpH, Ca²⁺K⁺NO₃^-, and HCO₃^-SO₄^2-Na⁺F^-. The results showed that both the ANN (CV) and ANN (B) models performed better than other optuna-based models during the test phase (RMSE = 0.041, MAE = 0.026, R2 = 0.971, RAE = 0.15 = 21 and CC = 0.986) and (RMSE = 0.041, MAE = 0.025, R2 = 0.969, RAE = 0.119 and CC = 0.975), respectively. SO₄^2-, Cl^- and F^- played an important role in the prediction accuracy. F- and SO₄^2- showed higher spatial autocorrelation, which affected groundwater quality degradation. In addition, the ANN (CV) and ANN (B) models showed a Gaussian distribution of model errors (small standard error, <1 %), indicating the stability of the model. These results indicate the efficiency of the ANN model in predicting groundwater quality in coastal areas, which would help regional water managers in real-time monitoring and management of sustainable groundwater resources.

This study investigated the adsorption of 4-Nonylphenol (4-NP) on aged microplastics (MPs) composed of polyethylene terephthalate (PET) and poly(butylene-adipate-co-terephthalate)/polylactic acid (PBAT/PLA). Morphological analysis revealed wear, wrinkles, and increased surface roughness in both aged MPs, with X-ray diffraction showing slight increases in crystallinity. Infrared spectroscopy showed an increase in the carbonyl index from 2.78 to 4.37 for PBAT/PLA and 0.51 to 2.32 for PET after aging. The natural water from the San Pedro River in Chile Atacama region (5.91 mS·cm^-1 conductivity, 3.25 PSU salinity, 2955 mg·L^-1 total dissolved solids, 435 mg·L^-1 CaCO₃ hardness) was used as the environmental medium and compared with a 0.01 mol·L^-1 CaCl₂ as a model solution. Kinetic modeling showed a decrease in 4-NP percentage removal from 90.0 % (2277 μg∙g^-1 adsorption capacity) to 50.2 % (1268 μg∙g^-1) for PET and from 86.8 % (2087 μg∙g^-1) to 70.3 % (1955 μg∙g^-1) for PBAT/PLA when comparing the model solution to natural water, with 30 and 84 h equilibrium times, respectively. Isotherm data showed that 4-NP/PET fits BET n-layer and Temkin models, while 4-NP-PBAT/PLA fits the Toth and Hill models The ionic composition of natural water induces cation attraction to polarized MPs surfaces, intensifying competition for adsorption sites. This involves ion and molecular cooperation, 4-NP reorientation, external diffusion effects, and surface oxidation variations, which are attributed to explaining the bilayer (PET) and monolayer (PBAT/PLA) formation. This work contributes to understanding MP pollution and the importance of considering the bioplastics life cycle, since their waste presents significant potential to resist external factors for transporting contaminants.

The Chili, Vitor and Quilca rivers and their tributaries in Peru serve as a vital water resource for both irrigation and domestic use in the surrounding communities and agricultural areas. The purpose of this study was to establish, for the first time, the presence, abundance, distribution and chemical identity of polymer microparticles in aqueous samples from these river basins. The results showed that, on average, filaments were the most dominant (71.4 %), followed by fragments (17.2 %) and film (6.74 %). Identification of the polymer types revealed that the most abundant type of MPs is polyethylene (40.8 %), followed by polypropylene (23.8 %), synthetic fibres (15.8 %), and other synthetic polymers. All samples showed the occurrence of microplastics, with a mean concentration of 35.34 MPs/m³, a maximum value of 172.70 MPs/m³ and a minimum value of 3.59 MPs/m³. The results reported in this study establish a baseline for the study area for the first time; in addition, the areas were established with a Pollution Indicator, and the Pollutant Load Index (PLI) was calculated, which reinforced the proposed identification, alerting the need to control clandestine urban and rural landfills, as well as the indiscriminate use of PE big bags in the agricultural catchment.

High intensity agricultural activities can lead to a decrease in soil fertility and an increase in soil bulk density, which may significantly impact the migration and transformation of pesticides in soil. As a new widely-used micro-toxic pesticide, gibberellic acid (GA₃) is more soluble and hydrophilic than most pesticides, which could readily migrate throughout the soil during water infiltration and impact groundwater quality. In this study, the leaching of GA₃ in saturated soils with different bulk densities (1.15-1.75 g/cm³) and infiltration rates (0.2215-0.0017 mm/s) were analyzed using column experiments. The migration and distribution of GA₃ in the soil with a depth of 50 cm were also investigated. The results indicated that GA₃ could completely penetrate the soil with bulk densities less than 1.45 g/cm³, and GA₃ mass variation in the effluent was normally distributed. The maximum mass of GA₃ in the effluent was calculated using the equation M_outlet(max) = 79.01 t^-0.97 (R² = 0.9811), and 83.69-93.16 % mass of the added GA₃ migrated downward in the soil. The analysis of the distribution of GA₃ in the soil showed that GA₃ accumulated in the upper soil layers with depths of 0-25 cm (the total depth of soil was 50 cm). In addition, the residual and hydrolyzed GA₃ amounts in the soil were 75.07-96.47 % and 5-30 % of the added GA₃, respectively. Overall, the soil bulk density and irrigation volume determine what type of impact that GA₃ may potentially have on the environment.

The current increase in microplastic (MP) occurrence worldwide is predicted to cause severe environmental crises in the future. Therefore, it is imperative to develop innovative MP removal technologies that can effectively mitigate MP emissions in any given scenario. This review discusses recent environmentally friendly advances in MP removal technologies that aim to overcome the limitations of current technologies, prevent secondary pollution, and utilize low energy. It also explores the potential applicability of these technologies under the current environmental conditions in South Korea. The core principles of these technologies, such as adsorption or flocculation, focus on minimizing the energy required to initiate and sustain these processes and on reducing the usage of adsorbents and flocculants. Employing microalgae as flocculants and triboelectricity for electrophoresis are identified as promising technologies. Incinerating MP-adsorbed materials from the process could be a viable disposal method, potentially serving as a source of heat energy. Consequently, technologies based on biochar or microalgae are especially advantageous in this context. The location where these technologies are applied plays a crucial role in their overall energy consumption. Ideally, implementation should occur as close as possible to points where MPs are found or within wastewater treatment plants. Froth flotation, microalgae flocculation, and triboelectricity-based electrophoresis are suitable methods in this regard. Establishing and enforcing administrative systems, laws, and policies globally to prevent MP occurrence remains critical. However, while these measures are vital, the most effective method for reducing MP occurrence is lowering plastic consumption alongside implementing stringent segregation and collection procedures.

Microplastics (MPs) have recently gained attention as emerging environmental contaminants, yet knowledge of their distribution, sources, and risks in freshwater lakes remains limited. This study examined the occurrence and risk of MPs in water and sediment samples from eight locations in Mohamaya Lake (Bangladesh) collected in April and May 2023. MPs were identified using stereomicroscopy and FTIR, revealing concentrations of 20-95 particles/L in water and 550-1900 particles/kg (d.w.) in sediment, with mean values of 50.62 ± 9.95 particles/L and 1068.75 ± 521.49 particles/kg (d.w.). Dominant MPs were blue fibers, 0-0.5 mm in size, with HDPE, PET and LDPE as the most common polymers. This study used four indices (nemerow pollution index-NPI, contamination factor-CF, pollution load index-PLI, and polymer hazard index-PHI) to assess MP pollution, revealing light to high contamination levels. While NPI indicated light pollution, CF, PLI, and PHI highlighted areas of moderate to high risk, with certain polymers showing high to extreme toxicity. This study deepens understanding of MP contamination in Bangladesh's freshwater lakes, underscoring the need for research on ecotoxicology, regulation, and associated challenges.

Tire wear particles (TWPs), as a prevalent form of microplastic pollution in aquatic environments, have been shown to adsorb antibiotics, potentially exacerbating their toxic effects. This study provides a comprehensive analysis of the adsorption of ofloxacin (OFL), ciprofloxacin (CIP), sulfadiazine (SDZ), and tetracycline (TC) on TWPs that have undergone various aging processes, including cyclic freeze-thaw and ozone aging. We observed a significant increase in the specific surface area (SBET) of TWPs after aging, from an initial 2.81 ± 0.29 to 6.63 ± 0.16 m²/g for ozone-aged TWPs. This enhancement in surface area and pore volume led to a respective 1.36-fold and 28-fold increase in adsorption capacity for OFL and CIP, highlighting the substantial impact of aging on TWPs' adsorptive properties. Conversely, the adsorption of SDZ and TC was reduced post-aging, suggesting a complex interaction between antibiotic physicochemical properties and TWPs' surface characteristics. The pseudo-second-order model, indicating chemisorption interactions, effectively described the adsorption kinetics, with the Freundlich isotherm model capturing the adsorption behavior more accurately than the Langmuir model. Our findings underscore the critical role of hydrophobic and electrostatic interactions in the adsorption process, particularly for SDZ and TC. This study's results offer crucial insights into the environmental implications of TWPs, emphasizing the need for further research on their role in the transport and fate of antibiotics in aquatic ecosystems.

This study analyzed surface water from the River Swat, Pakistan, using inductively coupled plasma mass spectrometry, multivariate statistical techniques, and US-EPA risk assessment models to evaluate the concentrations, distribution, pathways, and potential risks of arsenic (As) and heavy metals, including chromium (Cr), manganese (Mn), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), cadmium (Cd), mercury (Hg), and lead (Pb). The results revealed significant correlations (p ≤ 0.01) among metals that indicated common pollution sources, likely influenced by anthropogenic point and non-point activities. Along the monitored sites (S1-S10), the mass flow of ∑metals showed a dynamic pattern: progressively increasing downstream, decreasing at S6-S7, rising again at S7-S8, and then steadily declining toward S10, with Ni being the most abundant metal, followed by Cr > As> Cu > Mn > Co > Zn > Hg > Cd > Pb. The As and Heavy Metal Pollution Index (HPI), As and Heavy Metal Evaluation Index (HEI), and Pollution Index (PI) revealed variations in pollution levels, ranking the metals in the orders of Co > As> Cr > Cd > Mn > Hg > Ni > Pb > Cu > Zn, As> Cr > Ni > Hg > Cd > Co > Mn > Cu > Zn > Pb, and Hg > Ni > As> Co > Cu > Cd > Mn > Zn > Pb, respectively. However, according to the risk assessment, overall individual metal contamination in the River Swat water was below the ecological risk threshold (ERI 〈110). Where, the Chronic Daily Intakes (CDIs), Hazard Quotients (HQs), Hazard Indices (HIs), Cancer Risks (CRs), and Total Cancer Risks (TCRs) of Cr, Mn, Co, Ni, Cu, Zn, As, Cd, Hg, and Pb associated with daily river water intake and dermal contact indicate that long-term exposure to untreated river water may pose both carcinogenic and non-carcinogenic health risks to residents.

Dynamic monitoring of in-situ chemical oxidation (ISCO) of LNAPLs in groundwater is the foundation for evaluating remediation effectiveness. In this study, spectral (SIP) and time-domain induced polarization (TDIP) measurements are conducted in laboratory columns and sandboxes to monitor the ISCO of LNAPL for characterizing oxidant transport and quantifying contaminant consumption under different injection strategies. To support the interpretation, this was combined with total petroleum hydrocarbon (TPH), hydrochemistry and computed tomography (CT) measurements. Experiments were performed using two media, and the monitoring results showed similar variations in key parameters. The electrical resistivity, chargeability and TPH decreased significantly during ISCO remediation, while the hydrochemical parameters showed an increasing trend. Specifically, IP variations before and after injection revealed that more oxidant remained in the source area using a multiple-injection strategy compared to a single-injection strategy. The effect of contaminant consumption under well-controlled conditions on electrical resistivity was <3 % and the effect on chargeability was <8 %. In conditions with oxidant migration, the effect of oxidant on the resistivity and chargeability was similar at ∼89 % in the source area, whereas the oxidant had a greater effect on the resistivity (>58 %) than the chargeability (<40 %) outside the source area. Based on the experimental results, a conceptual model for the IP response during ISCO remediation is proposed and we delineate the pore structural characteristics of porous media based on the conceptual model. Oxidant injection develops a high conductivity environment and causes a decrease in LNAPLs content and number of interfaces, leading to the suppression of the IP response. In conclusion, IP measurement in combination with supporting information clearly enables the characterization of the ISCO remediation of LNAPLs in groundwater and facilitates the pore structure characterization of porous media based on the IP conceptual model.