Search Results (256)

The paper presents the results of investigations into the relationship between selected water quality parameters and hydrological streamflow drought in a small river situated in the Mazovian Lowlands in Poland. As hydrological streamflow drought periods become more frequent in Poland, investigations about the relationship between flow and water quality parameters can be an essential contribution to a better understanding of the impact of low flow on the status of water rivers. Data from a three-year study of a small lowland river along with significant agricultural land management was used to analyze the connection between low flows and specific water quality indicators. The separation of low-flow data from water discharge records was achieved using two criteria: Q90% (the discharge value from a flow duration curve) and a minimum low-flow duration of 10 days. During these periods, the concentration of water quality indicators was determined based on collected water samples. In total, 30 samples were gathered and examined for pH, suspended sediments, dissolved substances, hardness, ammonium, nitrates, nitrites, phosphates, total phosphorus, chloride, sulfate, calcium, magnesium, and water temperature during sampling. The study’s main aim was to describe the relation between hydrological streamflow droughts and chosen water quality parameters. The analysis results demonstrate an inverse statistically significant relationship between concentration and low-flow values for total hardness and sulfate. In contrast, there was a direct relationship between nutrient indicators, suspended sediment concentration, and river hydrological streamflow drought. Statistical tests were applied to compare the datasets between years, revealing statistical differences only for nutrient indicators. Full article

This study was developed to identify the optimal (most cost-effective) strategies to reduce sediment and phosphorus loadings in the Upper Soldier Creek, Kansas, USA, watershed using the Watershed Management Optimization Support Tool (WMOST) suite of programs. Under average precipitation, loading targets for upland total phosphorus (TP) could be met with use of grassed swales for treating urban area runoff and of contouring for agricultural runoff. For a wet year, the same target could be met, but with use of a sand filter with underdrain for the urban runoff. Both annual and daily TP loading targets from Total Maximum Daily Loads (TMDLs) were exceeded in simulations of best management practice (BMP) solutions for 14 alternative future climate scenarios. We expanded the set of BMPs to include stream bank stabilization (physical plus riparian restoration) and two-stage channel designs, but upland loading targets could not be met for either TP or total suspended solids (TSS) under any precipitation conditions. An optimization scenario that simulated the routing of flows in excess of those treated by the upland BMPs to an off-channel treatment wetland allowed TMDLs to be met for an average precipitation year. WMOST can optimize cost-effectiveness of BMPs across multiple scales and climate scenarios. Full article

The occurrence of toxic metal(loid)s in surface freshwater is a global concern due to its impacts on human and ecosystem health. Conceptual and quantitative metal(loid) models are needed to assess the impact of metal(loid)s in watersheds affected by acid rock drainage. Few case studies have focused on arid and semiarid headwaters, with scarce hydrological and hydrochemical information. This work reports the use of WASP8 (US EPA) to model Al, Fe, As, Cu, and SO₄²⁻ concentrations in the Upper Elqui River watershed in north–central Chile. Calibrated model performance for total concentrations was “good” (25.9, RRMSE; 0.7, R²-d) to “very good” (0.8–0.9, R²-d). The dissolved concentrations ranged between “acceptable” (56.3, RRMSE), “good” (28.6, RRMSE; 0.7 d), and “very good” (0.9, R²-d). While the model validation achieved mainly “very good” (0.8–0.9, R²-d) predictions for total concentrations, the predicted dissolved concentrations were less accurate for all indicators. Sensitivity analysis showed that the partition coefficient is a sensitive constant for estimating dissolved concentrations, and that integrating sorption and sediment interaction reduces the model error. This work highlights the need for detailed and site-specific information on the reactive and hydrodynamic properties of suspended solids, which directly impact the partition coefficient, sedimentation, and resuspension velocity calibration. Full article

Monitoring chlorophyll-a concentration (Chl-a) is essential for assessing aquatic ecosystem health, yet its retrieval using remote sensing remains challenging in turbid coastal waters because of the intricate optical characteristics of these environments. Elevated levels of colored (chromophoric) dissolved organic matter (CDOM) and suspended sediments (aka total suspended solids, TSS) interfere with satellite-based Chl-a estimates, necessitating alternative approaches. One potential solution is machine learning, indirectly including non-Chl-a signals into the models. In this research, we develop machine learning models to predict Chl-a concentrations in the Chesapeake Bay, one of the largest estuaries on North America’s East Coast. Our approach leverages the Extra-Trees (ET) algorithm, a tree-based ensemble method that offers predictive accuracy comparable to that of other ensemble models, while significantly improving computational efficiency. Using the entire ocean color datasets acquired by the satellite sensors MODIS-Aqua (>20 years) and VIIRS-SNPP (>10 years), we generated long-term Chl-a estimates covering the entire Chesapeake Bay area. The models achieve a multiplicative absolute error of approximately 1.40, demonstrating reliable performance. The predicted spatiotemporal Chl-a patterns align with known ecological processes in the Chesapeake Bay, particularly those influenced by riverine inputs and seasonal variability. This research emphasizes the potential of machine learning to enhance satellite-based water quality monitoring in optically complex coastal waters, providing valuable insights for ecosystem management and conservation. Full article

Stormwater runoff from areas with specific industrial, agricultural or logistic land use comprises a significant source of water pollution, yet research on its specific composition remains limited compared to urban stormwater pollution. This review synthesizes findings from different studies to analyze sampling methods, types of pollution parameters and their associated concentration ranges across various non-urban land use types, including industrial and commercial zones, transportation infrastructure (ports, airports, highways, railways) and agricultural areas. Studies differed in sample strategy, investigated phase (water, sediment) and analyzed chemical parameters. The latter can be grouped into sum parameters (e.g., total suspended solids (TSS), chemical oxygen demand (COD)), metals (e.g., nickel, copper, zinc, lead), nutrients (e.g., nitrogen, phosphorus), organic micropollutants (e.g., polycyclic aromatic hydrocarbons (PAH), perfluoroalkyl acids (PFAA)) and microbial contaminants. Results indicate that pollutant loads vary widely depending on land use, with industrial and railway areas showing the highest metal contamination, while agricultural and livestock farming areas exhibit elevated nutrient and microbial concentrations. The heterogeneity of the sampling, analysis and subsequent data processing hindered the statistical condensation of data from different studies. The findings underscore the need for standardized monitoring methods and tailored stormwater treatment strategies to mitigate pollution impact effectively. Full article

Satellite observations provide broad spatial coverage of complex coastal environments but may lack temporal resolution to capture rapid changes in these dynamic systems. This study explores the potential of the recently installed NASA Aerosol Robotic Network Ocean Color (AERONET-OC) in the Chesapeake Bay, USA, both for comparison with satellite remote sensing and to complement the satellite observations by filling temporal gaps at a fixed site. Using AERONET-OC’s effectiveness as a validation tool through comparisons with multi- and hyperspectral satellites, we find agreement between AERONET-OC and satellite remote sensing reflectance measurements in the Chesapeake Bay. We use AERONET-OC to estimate total suspended matter transport through the upper bay, revealing a 3-day lag of sediment plume transport from riverine discharge to the AERONET-OC site. During the 2023 Canadian wildfire smoke episode, AERONET-OC aerosol optical depth measurements in the Chesapeake Bay agree with satellite products while capturing diurnal variations that are not observable through daily satellite passes. This study demonstrates the potential of continuous in situ monitoring by AERONET-OC to complement satellite observations with higher frequency, important for capturing extreme events that may be missed by daily satellite overpass or are less frequent when cloudy. Full article

Extensive antibiotic use in swine production contaminates manure and wastewater with antibiotics. Discharging this waste into the environment, even after treatment, potentially fuels the spread of antibiotic resistance. This study investigated a full-scale swine wastewater treatment plant that combines coagulation–sedimentation, sand filtration, ozonation, activated carbon filtration, and a deaeration process. At each stage of this process, samples were collected and analyzed to determine their water quality parameters, antibiotic concentrations, and antibiotic resistance genes (ARGs). The experimental results showed coagulation–sedimentation effectively removed suspended solids (92.2%) and total phosphorus (96.9%). Ozonation significantly reduced antibiotic levels, including sulfamethazine by over 99.9%, although ARGs such as tetM, sul1, and sul2 were only removed at levels up to 95.9%. Interestingly, partial rebounds of sulfamethazine (438.9 μg/L) and marbofloxacin (0.40 μg/L) appeared in the final effluent, suggesting that desorption or operational factors (e.g., hydraulic fluctuation, filter media saturation, and pH) may affect the treatment process. In addition, strong correlations emerged between the levels of suspended solids and those of certain antibiotics (lincomycin, tiamulin), indicating particle-mediated sorption as a key mechanism. Even though ozonation and coagulation–sedimentation were found to contribute to the substantial removal of pollutants, the observed rebounds and residual ARGs highlight the need for optimized operational strategies and multi-barrier approaches to fully mitigate antibiotic contamination and inhibit the proliferation of resistant bacteria in swine wastewater. Full article

The offshore transport of coastal water masses in the East China Sea is vital for maintaining ecological stability. Understanding its spatial-temporal pathways helps clarify material transport and ecological responses. This study used total suspended sediment (TSS) data from the Korean Geostationary Ocean Color Imager to analyze TSS distribution and anomalies, combined with satellite-derived surface residual currents. Results show significant seasonal variations: coastal water masses expand to the 50 m isobath in winter and contract to the 20 m isobath in summer. Offshore transport pathways vary spatially, extending to the shelf edge north of 28° N but restricted by the Taiwan Warm Current south of 28° N. A persistent transport pathway near 28° N shifts from northeastward to eastward. Other pathways include one south of Hangzhou Bay (spring and autumn) linked to tidal mixing and another north of the Yangtze River estuary (summer) following the Yangtze River Diluted Water. These findings provide crucial observational insights for modeling material cycling in the East China Sea shelf. Full article

Sequencing batch reactor Grundfos technology (SBR-GT) system efficiently treats municipal and selected industrial wastewater, designed for small and medium-scale facilities. It offers advanced solutions for biodegradable wastewater, including municipal and food industry effluents. Important features include stable sedimentation under fluctuating influent conditions, no need for sludge recirculation, and full process automation. The system uses a static decanter and constant chamber filling for optimal oxygenation efficiency and reduced costs. The system uses a static decanter and constant chamber filling for optimal oxygenation efficiency and reduced costs. It is ideal for small settlements with variable inflow, such as towns, allowing flexible operation and cost-effective maintenance. Implementations showed stable parameters for COD (chemical oxygen demand), BOD5 (biochemical oxygen demand), total suspended solids (TSS), total nitrogen (TN), and total phosphorus (TP) and up to 99% pollutant reduction, demonstrating high effectiveness in regular and stormwater conditions. Using multivariate multiple linear regression, significant relationships were identified. A multiple regression analysis revealed a strong relationship between water quality parameters. Total suspended solids, Total nitrogen, and Total phosphorus collectively and significantly influenced both chemical oxygen demand and biochemical oxygen demand (p < 0.01 for all). The models explained a high proportion of variance, with R² values of 0.99 for COD and 0.93 for BOD5 (p < 0.001 for both). Specifically, TSS had a strong positive effect on COD (p < 0.001), while TN and TP also significantly affected COD (p < 0.01). Although the overall BOD5 model was highly significant, the individual effects of TSS, TN, and TP on BOD5 were not statistically significant in this model. This method demonstrated high effectiveness in both regular and stormwater conditions, enhancing overall treatment performance. Full article

The nitrogen budget and the effects of varying densities of sea grape (Caulerpa lentillifera) on water quality and the growth performance of Asian seabass (Lates calcarifer) in a polyculture system were evaluated. Four treatments were tested, each stocked with 20 fish (average weight: ~20 g; density: 2.66 kg/m³). Treatment 1 (control) contained no sea grapes, while treatments 2, 3, and 4 included 100, 200, and 400 g of sea grapes, corresponding to 0, 667 g/m³, 1333 g/m³, and 2666 g/m³, respectively. Significant (p < 0.05) reductions in total ammonia nitrogen (TAN), total suspended solids (TSS), and turbidity were observed with increasing sea grape density; however, no significant differences (p > 0.05) were found among the three sea grape treatments. Higher sea grape densities increased nitrite (NO₂–N) and nitrate (NO₃–N) concentrations due to enhanced nitrification. Approximately 65% of the nitrogen input originated from feed, but only 47.78–48.96% was assimilated into fish biomass. Nitrogen losses included 1.17–1.46% via water exchange and final drainage, while 45.27–50.76% was likely retained in sediments, volatilized, or lost through denitrification. Sea grapes effectively absorbed total nitrogen (TN), demonstrating their potential as biofilters for improving water quality without compromising fish growth performance. The optimal density was 100 g of sea grapes per 2.66 kg/m³ of seabass biomass, offering a sustainable strategy to enhance productivity while mitigating environmental impacts. Full article

The persistent challenge of achieving cost-effective total phosphorus (TP) removal in wastewater treatment necessitates innovative coagulant development. While polyaluminum chloride (PAC) demonstrates efficacy in eliminating total nitrogen (TN), ammonia nitrogen (NH₄⁺-N), suspended solids (SSs), and pH stabilization, its limitations in attaining economical TP removal remain unresolved. This study introduces a novel FeSO₄-Al₂(SO₄)₃ composite coagulant to address PAC’s shortcomings through systematic formulation optimization. Utilizing single-variable experiments and response surface methodology (RSM), we determined the optimal reagent combinations under simulated high-efficiency sedimentation tank conditions. The results revealed that the FeSO₄-Al₂(SO₄)₃ composite achieved a TP removal efficiency approximately 40% greater than the PAC at equivalent dosages. A cost–benefit analysis indicated an approximate 50% reduction in the chemical expenditure relative to conventional PAC-based systems. The optimized formulation demonstrated synergistic effects between the Fe²⁺ and Al³⁺ ions, enhancing the charge neutralization and sweep flocculation mechanisms. These findings establish FeSO₄-Al₂(SO₄)₃ as a technically and economically viable alternative for TP-centric wastewater treatment, with implications for process sustainability. Further investigations should validate the long-term operational stability across diverse water matrices and assess the environmental impacts of residual metal ions. Full article

In forested watersheds, suspended sediment concentration (SSC) is an important parameter that impacts water quality and beneficial use. Water quality also has impacts beyond the stream channel, as elevated SSC can violate Indigenous sovereignty, treaty rights, and environmental law. To address elevated SSC, watershed partners must understand the dynamics of the sediment regime in the basins they steward. Collection of additional data is expensive, so this study presents modeling and analysis techniques to leverage existing data on SSC. Using data from the South Fork Clearwater River in Idaho County, Idaho, USA, we modeled SSC over water years 1986–2011 and we applied regression techniques to evaluate correlations between SSC and natural disturbances (channel-building flow events) and anthropogenic disturbances (timber harvesting, hazardous fuel management, controlled burns, and wildfire). Analysis shows that SSC did not change over the period of record. This study provides a monitoring program design to support future decision making leading to reductions in SSC. Full article

This study investigates the hydrodynamic and morphological effects caused by non-powered floating objects (e.g., barges, pontoons, and floating or moored platforms) that are towed by external forces (such as tugboats) across flat, shallow seabeds. This study employs an integrated approach combining advanced computational fluid dynamics (CFD) simulations with multivariate polynomial regression analysis to systematically investigate the hydrodynamic and morphological effects of non-powered floating objects on sediment resuspension. A total of 96 simulation scenarios were conducted, of which 84 significant cases (where the floating object did not touch the seabed) were analyzed. Variations included bow geometries (blunt and raked), towing speeds, and operational parameters. The results indicate that, under similar towing speeds and clearance heights, blunt bows increase the suspended sediment concentration by approximately 90–190% compared to raked bows. The regression model, attaining an R-squared value of 0.9647, identified the Froude number, squat ratio, squared towing time, and object type as critical predictors of suspended sediment concentration. Furthermore, the interaction terms between the Froude number and object type were significant, enhancing the model’s predictive accuracy. These results underscore the importance of optimized design and operational strategies in minimizing the environmental impact of floating structures, especially in shallow marine environments where sediment dynamics play a crucial role in ecological balance. Careful consideration of towing speed, object geometry, and operational parameters can significantly reduce sediment resuspension, mitigating ecological consequences. Full article

Urbanization and the expansion of impervious surfaces have increased stormwater runoff volumes, altered runoff timing, and degraded water quality and aquatic ecosystems. Runoff from urban areas carries pollutants such as nitrogen, phosphorus, sediments, and heavy metals, which can adversely impact the physical characteristics of receiving waterbodies. Stormwater management programs aim to mitigate these effects using Best Management Practices (BMPs) to retain and treat stormwater on-site. However, in densely developed areas, space constraints and high costs often make traditional BMPs impractical. This study assessed the effectiveness of expanded shale, an engineered material, as a filtration medium in bioswales, a type of linear BMP commonly used in transportation infrastructure. Thirty scenarios were tested in a 16 ft (4.9 m) long plexiglass flume using expanded shale mixed with sandy clay soil. Due to the limited scope of this study, it focused on assessing the effectiveness of expanded shale in removing suspended sediments and reducing turbidity. Results showed that expanded shale achieved removal efficiencies ranging from 20% to 82% for total suspended solids (TSS) and −4% to 61% for turbidity under different conditions. It outperformed conventional filtration materials such as sand and gravel, requiring less channel length. Remarkably, even in a small-scale laboratory setting, expanded shale met the suspended sediment removal standard of 80%, demonstrating its potential as a highly effective filtration material alternative for urban stormwater management. Full article

Safety and ecological health are restricted by the high amount of suspended sediment in the Yellow River. To solve the problems of the high sediment content and siltation in the Yellow River, the Xiaolangdi Reservoir (XLDR) has been carrying out water–sediment regulation (WSR) since 2002. To clarify the effects of the water and sediment changes caused by WSR on microbial communities, we analysed the composition of the microbial communities and functional groups in surface water and sediments before and after WSR using high-throughput sequencing and microbial functional annotation. Proteobacteria, Actinobacteria, Bacteroidetes, and Firmicutes were detected as the main microbial communities in the Yellow River’s middle and lower reaches. The water temperature (WT), dissolved oxygen (DO), total nitrogen (TN), total phosphorus (TP), and evolution of the microbial communities were all correlated (p < 0.05). The biodiversity indices of the surface water and sediment microbes, respectively, greatly declined. The WSR programme broke down nutrients that had been adsorbed on the sediments, which diminished microbial metabolic activity and impaired the water bodies’ capacity to purify themselves. In summary, this study provides the biological information needed for the ecological conservation of the Yellow River basin, as well as insights into the changes in and response characteristics of microorganisms following severe disturbances in rivers with high sediment concentrations. Full article