Journal of contaminant hydrology最新文献

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.

Monitoring of long-term contaminant concentrations trends is essential to verify that attenuation processes are effectively occurring at a site. However, monitoring data are often affected by extreme variability which prevents the identification of clear concentration trends. The variability is higher in long-screened monitoring wells, which are currently used at many contaminated sites, although it has been known since the 1980s that monitoring data from long-screened wells can be biased. Understanding the factors that may influence the variability of monitoring data is pivotal. To this end, following hydrochemical conceptual modelling using a multi-method approach, the variability of hydrocarbon concentrations from fully screened monitoring wells was assessed over eleven years at a former oil refinery located in Northern Italy. The proposed methodology combined factor analysis with multiple linear regression models. Results pointed out a higher variability in hydrocarbon concentrations at the plume fringe and a lower variability at the plume source and core. 44-46 % of the total variability in measured hydrocarbon concentrations is due to "intrinsic plume heterogeneity", related to the three-dimensional structure of a contaminant plume, which becomes thinner at the edge, creating a vertical heterogeneity of redox conditions at the plume fringe. This variability, expressed as increasing concentrations of sulfate and decreasing concentrations of methane, represents a background variability that cannot be reduced by improving sampling procedures. The remaining 56-54 % of the total variability may be due to the non-standardization of some purging and sampling operations, such as pump intake position, purging and sampling time/flow rates and variations in the analytical methods. This finding suggests that monitoring improvements in fully screened wells by standardizing all purging/sampling operations or using sampling techniques that can reduce the actual screen length (e.g., packers or separation/dual pumping techniques) would reduce data variability by more than half.

Non-stationarity of climatic variables (e.g., temperature and precipitation) due to Climate Change (CC) can affect the migration processes of radionuclides released from nuclear activities. In this paper, a framework of analysis is developed to predict the evolution in time of contaminant concentration and fluence under different Climatic Boundary Conditions (CBCs) of precipitation scenarios provided by a climate model integrated with an accurate physical coupled hydraulic-transport model. A case study is worked out with respect to the migration of a radioactive contaminant (²³²Th) at Kirtland Air Force Base (Albuquerque, New Mexico, USA), for which the different CBCs considered are: i) stationary and ii) non-stationary precipitation. The effects of such alternative hypotheses on the physical modelling results are analysed, using a cross-wavelet analysis. It is shown that fluence is strongly affected by precipitation extremes, more than concentration, and it is claimed that a daily scale on the information and data of CBCs is necessary to model, with sufficient accuracy, the migration process and properly assess the impact of future CC on groundwater contamination.