River Water Research Articles

Postsynthetically Modified Cationic, Robust MOF Featuring Selective Separation of Carboxylate-Containing Pharmaceutical Drugs from Water at Neutral pH: Elucidation of the Adsorption Mechanism by Theory and Experiments.

The escalating levels of hazardous pharmaceutical contaminants, specifically nonsteroidal anti-inflammatory drugs (NSAIDs), in groundwater reservoir surfaces and surface waterway systems have prompted substantial scientific interest regarding their potential deleterious effects on both aquatic ecosystems and human health. Extraction of those pollutants from wastewater is quite challenging. Hence, the development of economic, sustainable, and scalable techniques for capturing and removing those pollutants is crucial to ensure water safety. Herein, we demonstrate a physicochemically stable, reusable, porous Hf(IV)-based cationic metal-organic framework (MOF), namely, 1'@MeCl for the aqueous phase adsorption-based removal of NSAIDs (diclofenac, naproxen, ibuprofen) from the wastewater environment. The highly positively charged surface of the 1'@MeCl MOF enables it to selectively extract more than 99% of diclofenac, naproxen, and ibuprofen contaminants within less than 30 s. With fast adsorption kinetics, very high adsorption capacities (Qe) were achieved at neutral pH for diclofenac (482.9 mg/g), naproxen (295.9 mg/g), and ibuprofen (219.5 mg/g). Moreover, the influence of changes in pH and coexisting anions on the adsorption property of the 1'@MeCl MOF was studied. Furthermore, the adsorption efficiency of 1'@MeCl in different real water environments was ensured by performing diclofenac, naproxen, and ibuprofen adsorption from tap, river, and lake water. Moreover, a 1'@MeCl-anchored cellulose acetate-chitosan membrane was developed successfully to demonstrate the membrane-based extraction of diclofenac, naproxen, and ibuprofen from contaminated water. Furthermore, a molecular-level mechanistic study was performed through experimental and computational study to propose the plausible adsorption mechanisms for diclofenac, naproxen, and ibuprofen over the surface of 1'@MeCl.

Migration characteristics of microplastics in riparian soils and groundwater.

Investigations have revealed the presence of microplastics in both soil and groundwater, but the migration characteristics from soil to groundwater remain incompletely understood. In this study, two sampling sections consisting of soil-groundwater-river water were established near Lianxi Bridge and Xilin Bridge along the Jiuxi River in Xiamen. A total of 22 soil samples, 36 groundwater samples, and 18 river water samples were collected. Microplastics were detected in all samples with an abundance range of 392-836 n/kg in soil (mean, 655 ± 177 n/kg), 0.58-2.48 n/L groundwater (mean, 1.23 ± 0.42 n/L), and 0.38-1.80 n/L in river water (mean, 0.86 ± 0.41 n/L). Flakes predominantly constituted the shape of microplastics found in soil, while fibers dominated those present in water. Black, yellow, and red were the dominant color types. Polyamide (PA) and polyethylene (PE) were the main components of microplastics within soils, whereas polyethylene terephthalate (PET), polypropylene (PP), and PA prevailed within water. Microplastic particle sizes ranged from 39 to 2498μm in soils, mainly from 29 to 3394μm in water. The upstream section displayed higher abundances of microplastic compared to the downstream, revealing the soil particles having an intercepting effect on microplastics. The distribution and migration of microplastics in soil and groundwater are affected by many factors, including natural and anthropogenic factors, such as soil depth, soil properties, pore structure, hydrodynamics, hydraulic connections between groundwater and surface water, the extensive utilization and disposal of plastics, irrational exploitation of groundwater, and morphology and types of microplastics. These research findings contribute to a better understanding of the pathways, migration capacity, and influencing factors associated with microplastic entry into groundwater, thereby providing valuable technical support for the development of strategies aimed at controlling microplastic pollution.

Structural alterations in scales of Capoeta capoeta (Güldenstädt, 1773) from heavy metal-contaminated river water.

Heavy metal pollution, especially in freshwater, is a serious problem for aquatic organisms and human health. In this study, the scales of Capoeta capoeta living in the Karasu River (Turkey), which is estimated to be contaminated with pollutants, especially heavy metals, were examined for structural anomalies. Two stations on the river were selected for this purpose. Fish and surface water samples were taken at the stations. The heavy metal analyses were carried out in the water and the fish tissue. Heavy metal pollution was detected in the surface water. It was also observed that some heavy metals (As, Cu, Cd, Cr, Mn, Pb, Ni, Zn) accumulate in the fish tissue. Significant structural differences were observed on the dorsal surface of the scales, such as interrupted primary radii, damaged circuli, damaged focus, damaged anterior scale margin, broken focus, deformed scale structure, scattered chromatophores, dilatation of primary radii, loss of focus, damaged annuli, symmetry shift in the lateral line canal, eroded circuli, damaged posterior scale margin, double focus, branching in the primary radii, asymmetric circuli, incomplete annuli and interrupted secondary radii in each of the fish collected from the contaminated site. Heavy metals are suspected to be responsible for the structural anomalies in the scales. Based on these observations, it can be said that fish scales can be used as an effective indicator of water quality.

Paraben residues in wastewater and surface water: a case study of KwaZulu Natal and Gauteng provinces (South Africa) during the COVID-19 pandemic

Introduction: The presence of pharmaceuticals and personal care products in environmental matrices is considered one of the major scientific concerns. Most of these substances are disposed of unchanged through wastewater treatment plants and sewage systems. Consequently, they are continuously introduced into the water systems and progressively contaminate surface, ground and drinking water. During the COVID-19 pandemic, a large number of emerging contaminants including parabens were released to the environment through various routes. In this study, the occurrence of parabens (methylparaben (MePB), ethylparaben (EtPB), propylparaben (PrPB), and butylparaben (BuPB) was investigated in wastewater samples from various wastewater treatment plants (WWTPs) and the receiving surface waters in KwaZulu Natal and Gauteng Provinces (South Africa).Methods: The samples were collected between October 2020 and December 2021, covering the 2nd, 3rd and 4th waves of the COVID-19 pandemic. A solid phase extraction protocol with high-performance liquid chromatography was used to extract and enrich parabens before analysis.Results and Discussion: Methylparaben (2.02–84.7 μg/L), EtPB (<0.24–24.8 μg/L), PrPB (<0.26–55.1 μg/L), and BuPB (<0.27–17.3 μg/L) were quantified in wastewater influent collected WWTPs of KwaZulu Natal Province. While <0.19–5.43 μg/L, <0.16–5.63 μg/L, <0.17–6.89 μg/L, and <0.19–5.32 μg/L for MePB, EtPB, PrPB, and BuPB, respectively, were quantified in effluent wastewater from the same province. The concentrations of MePB, EtPB, PrPB, and BuPB in influent wastewater from Gauteng Province were 2.58–123 μg/L, <0.24–33.6 μg/L, 3.77–73.4 μg/L and <0.27–85.8 μg/L, respectively. In effluent wastewater, concentrations ranging from 0.24–17.76 μg/L (MePB), <0.16–4.88 μg/L (EtPB), 0.69-12.5 μg/L (PrPB), and <0.19–4.726 μg/L (BuPB) were quantified. During the 4th wave, the concentrations of parabens in surface water were lower compared to the second and third waves of the pandemic. In general, the paraben residues in the surface of KwaZulu Natal Province (<0.08–16.4 μg/L) were higher than those in Gauteng Province (0.08-3.14 µg/L). Methylparaben and propylparaben were dominant in all investigated samples (wastewater and surface water), followed by ethylparaben. The ecotoxicological risk assessment was carried out for aquatic biota, which was estimated in terms of risk quotients (RQs). RQs for the target compounds in river water indicated that MePB and EtPB pose low risk, whereas PrPB and BuPB pose low to medium risk to aquatic organisms.

Research on Water Ecological Resilience Measurement and Influencing Factors: A Case Study of the Yangtze River Economic Belt, China

Industrial development and population expansion has had serious negative impacts on the water ecological environment, and enhancing water ecological resilience (WER) has become a new sustainable development goal. Current research on WER is mostly about ecological resilience assessment including water systems. In order to explore the WER of the Yangtze River Economic Belt (YREB), ecological resilience and water ecology were combined to form the concept of WER. Based on the “social-ecological” resilience perspective, a DCSMI (Driving Force—Carrying Capacity—State—Management—Innovation) WER evaluation index system was constructed, which consists of five subsystems. The WER of the YREB from 2011 to 2022 was measured by using game-theoretic combination weights and the comprehensive evaluation method, which were then combined with the kernel density (KD) estimation, the Thiel index, and the center of gravity-standard deviation ellipse (SDE) method to reveal the WER differences and spatial evolution characteristics of the YREB. Finally, the key factors influencing WER were explored using the BP-DEMATEL model. It was found that (1) the average value of WER in the YREB has declined from 0.4562 to 0.4442, the polarization of WER is obvious, the overall gap is on a widening trend, and the gap between different basins is the main reason for the differences in WER in the YREB. (2) The WER of the YREB presents an asymmetric U-shaped distribution pattern with the downstream optimal, upstream medium, and midstream worst, and the spatial evolution presenting a northwestern–southeastern pattern. (3) The key factors of the top-ranked provinces in the WER index are concentrated in the layer of the State (S) indicators, the middle-ranked provinces and the back-ranked provinces are more influenced by the Driving Force (D) and the Carrying Capacity (C) indicators, respectively, and the Management (M) and Innovation (I) indicators are distributed in several provinces. These results can provide theoretical support for the construction of “resilient cities” and water ecology optimization in the YREB.

Skyrocketing pollution: assessing the environmental fate of July 4th fireworks in New York City.

Pyrotechnic displays often lead to significant increases in poor air quality. The widespread environmental fate-involving air, water, and spatial-temporal analyses-of fireworks-produced pollutants has seldom been investigated. This study examined the environmental fate of pollutants from the largest fireworks event in the U.S.: Macy's Fourth of July Fireworks show in New York City (NYC). Real-time PM2.5 and gravimetric PM2.5 and PM10 were collected at locations along the East River of NYC. Airborne particles were assayed for trace elements (X-ray fluorescence) and organic and elemental carbon (OC/EC). River water samples were evaluated by ICP-MS for heavy-metal water contamination. Spatial-temporal analyses were created using PM2.5 concentrations reported by both EPA and PurpleAir monitoring networks for NYC and 5 other major metropolitan areas. The fireworks event resulted in large increases in PM2.5 mass concentrations at the river-adjacent sampling locations. While background control PM2.5 was 10-15 µg/m3, peak real-time PM2.5 levels exceeded 3000 µg/m3 at one site and 1000 µg/m3 at two other locations. The integrated gravimetric PM2.5 and PM10 concentrations during the fireworks event ranged from 162 to 240 µg/m3 and 252 to 589 µg/m3, respectively. Zn, Pb, Sb, and Cu more than doubled in river water samples taken after the event, while S, K, Ba, Cu, Mg, Fe, Sr, Ti, and Zn increased in airborne PM2.5 from the fireworks. Data from hyperlocal monitoring networks for NYC and other metropolitan areas yielded similar, but generally smaller, increases in PM2.5 levels. Fireworks shows have been associated with environmental contamination. This comprehensive analysis considers the fate of pollutants from the largest annual U.S. pyrotechnic show through air, water, and hyperlocal temporal characterization.

Simulation of Groundwater Dissolved Organic Carbon in Yufu River Basin during Artificial Recharge: Improving through the SWAT-MODFLOW-RT3D Reaction Module

To keep groundwater levels stable, Jinan’s government has implemented several water management measures. However, considerable volumes of dissolved organic carbon (DOC) can enter groundwater via water exchange, impacting groundwater stability. In this study, a SWAT-MODFLOW-RT3D model designed specifically for the Yufu River Basin is developed, and part of the code of the RT3D module is modified to simulate changes in DOC concentrations in groundwater under different artificial recharge scenarios. The ultimate objective is to offer valuable insights into the effective management of water resources in the designated study region. The modified SWAT-MODFLOW-RT3D model simulates the variations of DOC concentration in groundwater under three artificial recharge scenarios, which are (a) recharged by Yellow River water; (b) recharged by Yangtze River water; and (c) recharged by Yangtze River and Yellow River water. The study shows that the main source of groundwater DOC in the basin is exogenous water. The distribution of DOC concentration in groundwater in the basin shows obvious spatial variations due to the influence of infiltration of surface water. The area near the upstream riverbank is the earliest to be affected. With the prolongation of the artificial recharge period, the DOC concentration in groundwater gradually rises from upstream to downstream, and from both sides of the riverbank to the surrounding area. By 2030, the maximum level of DOC in the basin will exceed 6.20 mg/l. The Yellow River water recharge scenario provides more groundwater recharge and less DOC input than the other two scenarios. The findings of this study indicate that particularly when recharge water supplies are enhanced with organic carbon, DOC concentrations in groundwater may alter dramatically during artificial recharge. This coupled modeling analysis is critical for assessing the impact of recharge water on groundwater quality to guide subsequent recharge programs.

Phytoplankton diversity as a bioindicator in river waters

Water quality can be seen from the diversity of plankton in the waters. Plakton can also be considered as a bioindicator to determine whether the waters are polluted or not. This research was conducted by taking water samples in the waters of the Krueng Pase River and analyzing them in the laboratory. The results of the analysis show that the most common phytoplankton found the type Naviculla sp reached 10%. This type of phytoplankton belongs to the Bacillariophyceae class. Phytoplankton from this group can be a bioindicator of environmental pollution in water.Keywords: Bioindicator; Fitoplankton; Pollutan

Fast Determination of Eleven Food Additives in River Water Using C18 Functionalized Magnetic Organic Polymer Nanocomposite Followed by High-Performance Liquid Chromatography

A novel magnetic nanomaterial with Fe3O4 as the core, PS-DVB as the shell layer, and the surface modified with C18 (C18−PS−DVB−Fe3O4) had been synthesized by seeded emulsion polymerization. C18−PS−DVB−Fe3O4 retains the advantages of the chemical stability, large porosity, and uniform morphology of organic polymers and has the magnetic properties of Fe3O4. A simple, flexible, and efficient magnetic dispersive solid phase extraction (Mag-dSPE) method for the extraction of preservatives, sweeteners, and colorants in river water was established. C18−PS−DVB−Fe3O4 was used as an adsorbent for Mag-dSPE and was coupled with high-performance liquid chromatography (HPLC) to detect 11 food additives: acesulfame, amaranth, benzoic acid, tartrazine, saccharin sodium, sorbic acid, dehydroacetic acid, sunset yellow, allura red, brilliant blue, and erythrosine. Under the optimum extraction conditions, combined with ChromCoreTMAQC18 (5 μm, 4.6 × 250 mm), 20 mmol/L ammonium acetate aqueous solution and methanol were used as mobile phases, and the detection wavelengths were 240 nm and 410 nm. The limits of detection (LODs) of 11 food additives were 0.6–3.1 μg/L with satisfactory recoveries ranging from 86.53% to 106.32%. And the material could be reused for five cycles without much sacrifice of extraction efficiency. The proposed method has been used to determine food additives in river water samples, and results demonstrate the applicability of the proposed C18−PS−DVB−Fe3O4 Mag-dSPE coupled with the HPLC method to environment monitoring analysis.

Rethinking fish-friendliness of pumps by shifting focus to both safe and timely fish passage for effective conservation

Globally, catadromous freshwater eels of the genus Anguilla are of conservation concern, including critically endangered European eel (Anguilla anguilla). Pumping stations that move river water to a higher elevation severely impact eels during their seaward spawning migration. Fish-friendly pumps can mitigate fish injury and mortality but here we uniquely rethink a fish-friendly pump as a fish passage solution. In this pluriannual study, the seasonal timing of pump operation was misaligned with the typical silver eel migration period. Eels were almost exclusively nocturnal but night-time pumping represented as little as 5.6% a year. Night-time eel approaches were primarily influenced by pump duration and temperature, but did not align with lunar phase, unlike in unregulated rivers. After reaching the pumping station, eel passage was influenced by weedscreen aperture and increased when the aperture was increased. Passive sensor collision suggested non-pump infrastructure could cause injury and mortality to eels. It is therefore recommended pump operation should align with the timing of silver eel migration, weedscreen and pump entrance efficiencies should be maximised, and non-pump infrastructure must have low fish injury risk. Ultimately, considering the entire structure a fish passage solution will help ensure fish-friendly pumps have high conservation value for anguillid eels globally.

Self-ratiometric fluorescence approach based on room-temperature instantaneously synthesized carbon dots from Folin’s reagent and ethanol amine for determination of nitroxinil in water, milk, and food samples

BackgroundNitroxinil has been used extensively to treat parasitic worms, mainly Fasciola, in food-producing cattle and sheep. The reported methods for nitroxinil analysis included expensive instrumentation, the need for skilled operators, and tedious procedures. Fluorimetry is one of the fastest and simplest methods widely used; hence, we aimed to develop a simple, cost-effective, and convenient fluorometric approach for the estimation of nitroxinil in various matrices. Compared with other detection methods, self-ratiometric fluorescent probes are considered a promising approach for the detection of analytes as their detection accuracy overcomes traditional fluorescence of the sensing probe in that it is not affected by the probe concentration, solution polarity, instrument parameters, and other factors. In this research, room temperature instantaneously synthesized carbon dots were used as a sensitive and selective self-ratiometric probe for the determination of the veterinary medicine nitroxinil in various matrices. ResultsA room-temperature synthesized quinone-ethanolamine carbon dots (RTQECDs) was fabricated using the instantaneous reaction of sodium 1,2-naphthoquinone-4-sulfonate (Folin’s) with ethanolamine, without any energy/catalyzing reagents, for the first time. The prepared carbon dots show green-blue fluorescence at 450 nm upon exposure to UV light at 365 nm with a quantum yield of 26.6%. Upon interaction with nitroxinil, the fluorescence intensity of RTQECDs at 450 nm is quenched and shifted to a longer wavelength at 475 nm. Meanwhile, the fluorescence of RTQECDs at 400 nm (absorbance maxima of nitroxinil) was more extremely quenched under the same conditions. Taking this in hand, a new RTQECDs self-ratiometric probe was developed for the determination of nitroxinil using the decrease in peaks at 450 nm and 400 nm and the shift of the fluorescence maxima to 475 nm as built-in reference peaks. The probe showed a quantitative increase in signal output of F475/F400 in the range of 0.10-30.0 μg/mL nitroxinil with a limit of detection of 30.0 μg/mL. The nitroxinil-sensing mechanism using RTQECDs is mainly ascribed to the partial secondary blue-type inner filter effect (IFE). The designed study was applied for the estimation of nitroxinil in veterinary dosage forms (recoveries; 99.78%−100.35%), river water (recoveries; 98.55%−101.53%), and (meat, liver, kidney, and milk (recoveries; 97.60%−104.25%). SignificanceThe novelty of our work includes the immediate synthesis of the sensing probe at room temperature, as well as its use as the self-ratiometric fluorescence probe for the determination of nitroxinil in veterinary samples, river water, and food products with excellent sensitivity down to 30 ppb. RTQECDs own the highest response and selectivity to nitroxinil compared with cations, anions, as well as other co-administrated drugs, including cefotaxime and ivermectin.

Chemical weathering and CO2 consumption rates of the Koshi River Basin: modelling and quantifying

The Koshi River is a typical river originating from the Tibetan Plateau that drains into the Indian Plain. To quantify the chemical weathering and CO2 consumption rates of the upstream alpine meltwater-supplied mountainous and downstream rainfall-impacted temperate plain regions, 46 river water samples were collected at 23 sites during monsoon and post-monsoon seasons, and major ions concentrations were measured in the laboratory. The forward model was applied to calculate carbonate weathering rate (CWR), silicate weathering rate (SWR), and their CO2 consumption rates ([CO2]car and [CO2]sil). For investigating the hydrological impacts, correlation analysis was applied between the chemical weathering rates and different runoff components based on the Spatial Process in Hydrology model at each sampling site. Results show that carbonate and silicate rock weathering control the river water chemistry. The average silicate weathering rate is 7.37 tons/km2/yr, consuming 3.40 × 105 mol/km2/yr CO2 while considering sulfide-involved carbonate weathering, the carbonate weathering rate is 26.35 tons/km2/yr, consuming 3.82 × 105 mol/km2/yr CO2. Overall, chemical weathering and CO2 consumption rates are enhanced in monsoon season in both the upstream and downstream regions owing to the intense hydrological cycle. These rates are relatively higher in the alpine upstream region during the post-monsoon season due to intense physical erosion, and higher in downstream during the monsoon season due to the greater volume of water. The significant positive correlations between snowmelt runoff with CWR and [CO2]car indicated that the rising precipitation and temperature leading to enhanced snowmelt would increase the carbonate weathering rate. Hence, this study provides a valuable understanding of the spatiotemporal variations in river hydrochemistry and the role of hydrology in shaping chemical budget within the snow and glacier-fed Himalaya River Basins.

Assessment of heavy metal concentration in the water of major carp breeding River Halda, Bangladesh

Heavy metal contamination in river water is a result of anthropogenic sources like industrial waste, tanneries, used fertiliser, and sewage discharge. Bioaccumulation and toxicity of heavy metals are alarming concerns for the natural carp breeding ground of the one and only river Halda of Bangladesh. Seven heavy metals (Fe, Mn, Cu, Co, Ni, Zn, and Cr (VI)) were assessed in this study following standard methods by gathering data from 36 sampling points that are situated along the area between the origin of Halda and Kalurghat confluence point of Halda and Karnofuli. An atomic absorption spectrophotometer was used for the measurement of the heavy metals, and the correlation between the parameters was determined using principal component analysis (PCA). The concentration of heavy metals ranged from 0.316 to 3.216 mg/L for Fe, 0.023–0.236 mg/L for Mn, 0.022–0.044 mg/L for Cu, 0.022–0.051 mg/L for Co, 0.002–0.008 mg/L for Ni, 0.037–0.282 mg/L for Zn, and 0.013–0.146 mg/L for Cr (VI), respectively. Cu and Mn values in some points were above the permissible limit, but other metal contents were within the permissible limit.

Synergistic SERS enhancement of NiCo-LDHs microurchins and silver nanoparticles for ultra-sensitive and reusable detection of thiabendazole

Two-dimensional layered semiconductor materials as a distinctive class of materials are comprehensively explored for widespread applications due to narrow bandgap, controllable morphology, and tunable metal cation composition. Herein, we constructed a sensing platform of surface enhanced Raman spectroscopy (SERS) by combination of nickel‑cobalt layered double hydroxide (NiCo-LDH) microurchins and plasmonic silver nanoparticles (Ag NPs) for fungicide detection of thiabendazole (TBZ). The NiCo-LDHs/Ag-NPs microcomposites consist of NiCo-LDHs microurchins having a large number of nanoneedles deposited with photoreduced Ag NPs. The SERS platform with NiCo-LDHs/Ag-NPs shows an excellent SERS performance for TBZ detection, including an ultra-low detection limit of 1.49 × 10−11 M, a sublime enhancement factor of 1.71 × 109, high uniformity, good reproducibility, and long-term storage stability. The ultrahigh SERS activity of NiCo-LDH/Ag-NPs can be attributed to strong electromagnetic enhancement in the nanoscale gaps between Ag NPs, massive charge transfer through large-area NiCo-LDH/Ag-NPs interfaces, and the synergistic action of electromagnetic and charge transfer mechanisms. Besides, the unique morphology of NiCo-LDHs/Ag-NPs microcomposite provides a broad surface area for adsorption of TBZ molecules for further Raman signal enhancement. The practicability of the proposed SERS platform is confirmed by detecting TBZ in the real samples of apple juice and river water. The exceptional self-cleaning capability of the NiCo-LDHs/Ag-NPs microcomposite with an retention rate of 81.97 % even after the fifth degradation cycle underscores its impressive sustainable reusability and cost-effectiveness. The findings in this work lay the foundation for the development of high-performance SERS platforms to ensure food safety and environmental protection.

Sustainable synthesis of fluorescent polymercarbon dots@PVA for sensitive chlortetracycline detection.

Antibiotic residues persist in the environment and represent serious health hazards; thus, it is important to develop sensitive and effective detection techniques. This paper presents a bio-inspired way to make water-soluble fluorescent polymer carbon dots (PCDs@PVA) by heating biomass precursors and polyvinyl alcohol (PVA) together. For example, the synthesized PCDs@PVA are very stable with enhanced emission intensity. This property was observed in a wide range of environmental conditions, including those with changing temperatures, pH levels, UV light, and ionic strength. PCDs@PVA detected the antibiotic chlortetracycline (CTCs) with great selectivity against structurally related compounds and a low detection limit of 20 nM, demonstrating outstanding sensitivity and specificity. We confirmed the sensor's practical application through real sample analysis, yielding recovery rates of 98%-99% in samples of milk, honey, and river water. The synthesized PCDs@PVA fluorescence sensor was successfully used for CTCs detection in real samples.

Comparative analysis of water quality index and river classification in Kereh River, Penang, Malaysia: Impact of untreated swine wastewater from Kampung Selamat pig farms.

The Kereh River in Penang, Malaysia, has faced severe pollution for over 40 years due to untreated wastewater from swine farms in Kampung Selamat, discharged via stormwater drains. Despite official claims that all 77 swine farms treat their wastewater to meet regulatory standards, local non-governmental organizations and villagers have challenged this, though their concerns lack scientific backing. This study evaluates the river's water quality by analyzing samples from upstream (US), midstream (MS), and downstream (DS), and from Parit Cina-Parit Besar, a conduit for untreated swine wastewater. Fourteen parameters were measured against Malaysia's National Water Quality Standards (NWQS). Significant differences were found in six parameters: ammonium nitrogen (AN), biochemical oxygen demand (BOD), chemical oxygen demand (COD), dissolved oxygen (DO), total suspended solids (TSS), and oil and grease (OG). While Dunn's post hoc pairwise comparison showed no significant differences among river segments, mean values indicated increased pollution downstream, particularly after the convergence with untreated swine wastewater. River classification worsened, with water quality index dropping from 69.88 ± 11.37 score (Class III) US to 38.49 ± 12.74 and 50.44 ± 3.14 scores (Class IV) MS and downstream, respectively. A significant positive correlation between E. coli and AN (r = 0.71, p < 0.01) suggests a common point source pollutant, particularly the untreated swine wastewater. The river exhibits low oxygen levels and high organic matter and nutrient concentrations, especially MS and downstream, highlighting substantial ecological and public health risks. Effective enforcement of waste treatment regulations and enhanced monitoring are crucial for mitigating pollution and restoring the river's ecosystem. Collaboration between authorities and pig farmers is essential to improve water quality and maintain the river's ecological balance. PRACTITIONER POINTS: Severe Kereh River pollution: Untreated swine wastewater from Kampung Selamat pig farms, primarily via Parit Cina-Parit Besar, has degraded the river for over 40 years. Regulatory non-compliance: Despite official claims, untreated swine wastewater continues to pollute the river, challenging regulatory standards. Significant pollution indicators: Elevated levels of AN, BOD, COD, DO, TSS, OG, and E. coli signal severe pollution midstream and downstream. Water quality index drop: WQI scores classify midstream and downstream sections as polluted, indicating worsening conditions downstream. Urgent need for action: Enforcing regulations, improving wastewater treatment, and relocating pig farms are crucial for restoring the Kereh River.

Evaluation of SENTINEL-2 products-based algorithms in estimating water pollutants of the River Niger in Bamako

Monitoring surface water quality on a spatio-temporal scale is very important to restrict the entry of polluting components into water bodies, particularly rivers. Traditional techniques of assessing water quality are typically costly and time-consuming. With the advent of remote sensing technologies and the availability of high-resolution satellite images in recent years, a significant opportunity for water quality monitoring has arisen. Our study aims to test the use of Sentienl-2 multispectral imaging sensors in estimating three important water quality parameters: chlorophyll-a, Colored Dissolved Organic Matter and Total Suspended Matter in Niger River. Sentinel-2 satellite data were acquired in 2020. Atmospheric correction was performed using Sen2cor from the Sentinel toolbox to obtain a geometrically corrected Sentinel-2 multispectral image. We selected multiple water-body indices from the literature based on their spectral reflection characteristics, analyze correlations between the reflectance values of water body indices and the water quality parameters of synchronous measured sampling points in order to obtain an optimal water body index for estimating water quality parameters (WQP) in Niger River. Five regression functions were used in this study: linear regression, exponential, logarithmic, power and polynomial regression. The performance and accuracy of these regression models were evaluated by correlating spectral reflectance band ratio against the in situ water quality parameters (WQP) concentrations. Polynomial regression gave a higher performance and accuracy based on their R values. The best spectral index was selected to assess the spatio-temporal distribution of water pollutants in the Niger River in Bamako and its surroundings. The results showed that the polynomial regression of 6th degree provided the best fit had the best spectral band ratio and in situ Chl-a, CDOM and TSM concentrations which were respectively achieved with band index of B2/B3 (R2 = 0.78), B3/B6 (R 2 = 0.79) and B3/B4 (R 2 = 0.63). Therefore, the best band ratio was selected to evaluate Chl-a spatio-temporal in Niger River water in Bamako. The results of this study showed seasonal variability of the water pollutants in the Niger River. This highlights the potential of the Sentinel-2 products for water quality analysis. As a conclusion, the Sentinel-2 images could be helpful for precise water quality control of Niger River in Bamako.

Poly(allyl alcohol-co-vinyl acetate)-grafted Concrete Waste for Adsorptive Removal of As(III)

This study focused on the synthesis of concrete waste grafted with a polymer of allyl alcohol and vinyl acetate as a novel nano adsorbent and the investigation of its ability in the adsorptive removal of Arsenic (As(III)) from aqueous solutions. The prepared nano adsorbent was characterized using X-ray diffraction, thermogravimetric analysis, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Fourier-transform infrared spectroscopy. Various parameters were optimized by response surface methodology and central composite design model to achieve the highest As(III) removal efficiency, including the solution's temperature, contact time, and pH. The model predicted a maximum removal efficiency of 92% under the optimal conditions (temperature = 25 °C, contact time = 24 min, and pH = 7), resulting in a sorption capacity of 6.81 mg g-1. The zero point of charge for the nano adsorbent was obtained at about 6.5. The experimental data for As(III) sorption onto the nano adsorbent was well-fitted by the Freundlich isotherm and pseudo-1st-order kinetic models. This suggests that the adsorption process involves the formation of a multilayer of As(III) on the adsorbent surface, and it occurs through physical interactions rather than chemical reactions. The reusability of the nano adsorbent was evaluated, demonstrating a removal efficiency exceeding 72% even after seven recycling cycles. The presence of interfering cations influenced the removal efficiency in the following order: Pb2+>Mn2+>Cu2+>Zn2+>Ni2+. The prepared nano adsorbent showed significant efficiency in removing As(III) from well water and river water samples, with a repeatability range of 1.09-2.51%.

Evaluation of turbidity removal efficiency from Karun river water using polyaluminum chloride and chitosan

This study was conducted with the aim of evaluation of turbidity removal efficiency from Karun river water using polyaluminum chloride and chitosan. Chitosan is a linear cationic polyelectrolyte with high positive electron charge (one positive charge per glucose amine unit). Chitosan is used in water purification systems as coagulant along with common coagulants (alum, chlorferric). This biopolymer is also used as a primary coagulant. Chitosan has a higher ability to coagulate colloidal particles than synthetic polyelectrolytes, most of which lack the property of biological degradation in the short term, and some of them cause carcinogenesis and genetic mutation in humans. Therefore, the use of chitosan is preferable to artificial polyelectrolytes from an environmental point of view. This research was conducted on the laboratory scale using a jar test device at the water treatment plant in Ahvaz. In this study, various parameters such as pH, polyaluminum chloride concentration and chitosan concentration were present as variables. After preparing the samples and just before starting jar tests, in the rapid mixing cycle of 200 rounds per minute, the optimal pH to remove the turbidity obtained 8. Also, the optimal dosages of polyaluminum chloride and chitosan were selected as 4 ppm and 0.04 ppm, respectively. Also the main mechanism for destabilizing clots and removing turbidity was bridging between the particles. In this condition, the removal of turbidity showed the highest efficiency. On the other hand, chitosan created clots with a higher weight and, as a result, better settling ability. Therefore, chitosan was a suitable choice to remove turbidity from water.

Lateral Transport Controls the Tidally Averaged Gravitationally Driven Estuarine Circulation: Tidal Mixing Effects

Abstract In classic models of the tidally averaged gravitationally driven estuarine circulation, denser salty oceanic water moves up the estuary near the bottom, while less dense riverine water flows toward the ocean near the surface. Traditionally, it is assumed that the associated pressure gradient forces and salt advection are balanced by vertical mixing. This study, however, demonstrates that lateral (across the estuary width) transport processes are essential for maintaining the estuarine circulation. This is because for realistic estuarine bathymetry, the depth-integrated salt transport up the estuary is enhanced in the deeper estuary channel. A closed salt budget then requires the lateral transport of this excess salt in the deeper channel toward the estuarine flanks. To understand how such lateral transport affects the estuarine salt and momentum balances, we devise an idealized model with explicit lateral transport focusing on tidally averaged lateral mixing effects. Solutions for the along-estuary velocity and salinity are nondimensionalized to depend only on one single nondimensional parameter, referred to as the Fischer number, which describes the relative importance of lateral to vertical tidal mixing. For relatively strong lateral tidal mixing (greater Fischer number), salinity and velocity variations are predominantly vertical. For relatively weak lateral tidal mixing (smaller Fischer number), salinity and velocity variations are predominantly lateral. Overall, lateral transport greatly affects the estuarine circulation and controls the estuarine salinity intrusion length, which is demonstrated to scale inversely with the Fischer number.