Surface Water Contamination Research Articles

A predictive assessment of the uranium ore tailings impact on surface water contamination: Case study of the city of Kamianske, Ukraine

In this study, we present an assessment of the uranium ore tailings impact on groundwater and surface water contamination. The radioactive materials were deposited in the tailings storage facility “Dniprovske” (the city of Kamianske, Ukraine) from 1954 to 1968; now it contains about 5.85·106 m3 of hazardous waste on the area of about 76 ha in the floodplain of the Dnipro river. The lack of a proper waterproof screen below deposited tailings and in the earthen dam led to permanent watering of radioactive materials, their leaching and migration in groundwater into the nearest small Konoplianka river. We used the reports on previous site-specific studies conducted in 1999–2016, monitoring results, and the field studies conducted in 2022 with the authors’ team participation. The calculations performed with the advection-dispersion model to simulate transport of radionuclides 238U, 230Th, 226Ra and 210Pb through the embankment to the Konoplianka river and dilution relations were compared to the monitoring data of the surface water quality. Among four radionuclides, uranium poses the greatest risks today; the subsurface runoff increases its concentration in the Konoplianka river water by several times over the background value. It is estimated that due to much more intensive sorption in the shallow aquifer, the contribution of 226Ra and 210Pb to the increase in radioactivity of Konoplianka river water is insignificant compared to uranium, whereas the migration front of 230Th has probably not yet reached the riverbank. In the next 50 years the radionuclide fluxes will increase by 1.3–3.7 times for different isotopes, with the uranium subsurface runoff growing at a slower rate than nowadays. These results are of high significance for improving hydrological, hydrogeological, and geotechnical monitoring on this hazardous facility to maintain its radiation safety.

Spatio-temporal patterns of microplastic contamination in surface waters of Hooghly River Estuary: Causes and consequences

We conducted a pilot study in Hooghly River Estuary (HRE) at ten stations covering rural, urban and tidally mixed stretches to the confluence to quantify levels of microplastic (MP) contamination in HRE, the first distributary of the major River Ganga. Surface water samples from the HRE were contaminated with MPs. Stations, within the city recorded the highest concentration of MPs. Filamentous type and white/transparent MPs were found in higher concentrations. The MP concentration was positively correlated with population density, and volume of sewage discharged in the vicinity. Size range of abundant MPs suggests that larger copepods, ichthyoplankton and zooplanktivorous fish are more susceptible to MP ingestion and interference. This study provides an insight into the MP contamination in lower stretch of the river estuary and impacts of Kolkata city on MP pollution, which can be used as baseline information in predicting the peak contaminated stretch and appraise precise mitigation.

MICRIBIOLOGICAL ASSESSMENT OF DRINKING WATER AND PERVASIVENESS OF WATER BORN DISEASES IN DUNGARPUR, RAJASTHAN

INTRODUCTION: This study assessed E. coli counts in drinking water from different sources and illustrates the high prevalence of gastrointestinal diseases in Dungarpur districts of southern Rajasthan, India. METHODOLOGY: The microbiological parameters studied were pathogen detection, total coliform count and total viable count. Microbiological analysis of water samples were performed as described in Standard Methods for the Examination of Water and Wastewater (APHA - AWWA, 2005 and Chhabra, 2008). Total coliform count performed by the Most Probable Number (MPN) method, which is commonly used as an indicator of potability of water. Presence of the bacteria from Enterobacteriacae family was confirmed using IMViC test. The data of Indoor and Outdoor patients for such disease were collected.RESULT AND DISCUSSION: Seasonal fluctuation in coliform counts was found to be prominent and varied from over 200 MPN/ 100 ml in winter to more than 1600 (over the measurable limit) in rainy season in three water bodies. Escherichia coli counts ranged from 17 to 500 MPN/100 ml for all the sampled sites. E. coli and Total coliform were highest in rainy season. Results of IMViC test indicates that in rainy season except for Margia Dam all the water bodies were laden with all five categories of enteric bacteria namely E. coli, Shigella, Citrobacter and Klebsiella/ Enterobacter. The contamination is significantly higher during the wet season compared to dry season, due to WBD patients does exhibit a trend that in late summer and rainy month’s incidence of the disease symptoms intensifies. CONCLUSION: Dungarpur district was analyzed and same pattern of seasonal variation in microbial counts of water samples and similar hospital data trend was observed. So, somehow the microbial contamination of surface water and run-off reaches the ground-water table. Therefore, hospital data confirms that the source of drinking water plays a strong, positive and significant association with waterborne diseases.

Elevated sediment radionuclide concentrations downstream of facilities treating leachate from landfills accepting oil and gas waste

Management of oil and gas (O&G) waste streams from extraction of unconventional reservoirs challenges the sustainable development of these reservoirs. Landfilling of waste materials is an emerging strategy for unconventional O&G waste disposal. However, the effectiveness of effluent management systems designed for historical landfill waste streams in treating O&G waste is not established. This creates the potential for contamination associated with landfills accepting O&G waste. Yet, tracers of O&G waste are not necessarily included in routine effluent monitoring and environmental surveillance monitoring is too sparse to reliably detect this contamination. This study reviewed administrative records and analyzed grab samples of surface waters and stream sediments near effluent outfalls from facilities accepting O&G waste to evaluate this potential contamination. Administrative records are conflicting and inadequate, with only one landfill out of twenty-five agreeing within a factor of two between waste delivery and receipt volume reporting in 2019. Moreover, total radium was enriched in sediments downstream of effluent discharges, up to 4x relative to upstream values, magnitudes consistent with sediment accumulations downstream of known O&G waste inputs. Water chemistry measurements indicate that the largest upstream to downstream changes are consistent with O&G waste chemistry. These findings suggest landfill effluent influenced by O&G waste should be carefully scrutinized to avoid potential contamination of surface waters.

Indigenous food sources as vectors of Escherichia coli and antibiotic resistance

The contamination of surface waters by fecal bacteria, measured by the number of Escherichia coli, is a significant public health issue. When these bacteria are also resistant to antimicrobials, infections are more complicated to treat. While water is regularly tested at recreational sites, wild-harvested foods, known as mahinga kai by the indigenous Māori people of Aotearoa New Zealand, are commonly overlooked as a source of exposure to potential pathogens and antimicrobial resistance (AMR). We investigate two likely sources of risk from harvesting aquatic wild foods. The first is water contact, and the second is contact with/ingestion of the harvest. We used E. coli as a proxy for microbial water quality at harvesting sites. Two popular mahinga kai species were also harvested and assessed. We found antibiotic-resistant bacteria on watercress (Nasturtium officinale) and cockles (Austrovenus stutchburyi). One-third of E. coli isolates were conjugative donors of at least one resistance phenotype. Tank experiments were used to track the internalization of E. coli by Greenshell/lip mussels (Perna canaliculus). Greenshell mussels kept at environmentally relevant concentrations of E. coli were colonized to levels considered unsafe for human consumption in 24 h. Finally, we measured horizontal gene transfer between bacteria within the shellfish, what we termed ‘intra-shellular’ conjugation. The transmission frequency of plasmid RP4 was significantly higher in mussels than in water alone. Our results indicate that shellfish could promote the dissemination of antibiotic resistance. They highlight the need to limit or reduce human pathogenic bacteria where food is gathered.

Tracking down unknown PFAS pollution – The direct TOP assay in spatial monitoring of surface waters in Germany

PFAS contamination of surface waters in central Europe was investigated in a spatial monitoring using suspended particulate matter and sediment samples. The samples were collected in 2021 at 171 sampling sites in Germany and at five sites in Dutch waters. All samples were analyzed for 41 different PFAS by target analysis to establish a baseline for these compounds. In addition, a sum parameter approach (direct Total Oxidizable Precursor (dTOP) assay) was used to investigate the PFAS load in the samples more comprehensively.PFAS pollution varied widely between water bodies. Target analysis detected ∑PFAS concentrations between <0.5 and 53.1 μg kg−1 dry weight (dw), while levels of <1.0–337 μg kg−1 dw were determined by dTOP assay. Associations were observed for ∑PFSAdTOP and the percentage of urban area in the vicinity of the sampling sites and, less strongly, for distances to industrial sites (i.e. galvanic/paper) and airports. PFAS hotspots were identified by setting the 90th percentile of the data sets for ∑PFAStarget or ∑PFASdTOP as a threshold. Of the 17 hotspots identified by target analysis or dTOP assay, respectively, there were only six overlaps. Thus, 11 highly contaminated sites could not be identified by classical target analysis.The results demonstrate that target analysis captures only a fraction of the actual PFAS load, while unknown precursors remain undetected. Consequently, if only the results of target analysis are considered in assessments, there is a risk that sites heavily polluted with precursors will not be identified delaying mitigation actions and risking prolonged negative impacts on human health and ecosystems. Moreover, effective PFAS management requires establishing a baseline for PFAS using target and sum parameters such as the dTOP assay, and then monitoring this baseline on a regular basis to support emission control and to inform risk management of its effectiveness.

Hydrogeochemistry and Mercury Contamination of Surface Water in the Lom Gold Basin (East Cameroon): Water Quality Index, Multivariate Statistical Analysis and Spatial Interpolation

Artisanal and small-scale gold mining activities have an impact on natural resources and human health. This study addresses the assessment of surface water quality in the Lom gold basin. A combined approach of water quality index calculation, multivariate statistical analysis and spatial interpolation was used. Sampling was performed at 15 stations during low- and high-water periods in 2021 for classical physicochemical parameters and total mercury measurements. The results show that the physicochemical parameters were below drinking water standards for both periods, except for pH, total suspended solids and total mercury. These waters show a large cation deficit as well as an anion deficit. The water chemistry is controlled by precipitations and silicate dissolutions in rock that convert the water into the Ca-HCO3 and Ca-Mg-HCO3 types. The level of mercury contamination varied from acceptable to high due to high flow rates during high water that cause a dilution effect for the mercury concentration upstream and its accumulation downstream. The water quality varied from excellent to very poor with better quality during the high-water period. The Lom watershed is locally affected by physical and chemical pollution due to the abundance of suspended solids and mercury resulting from the different gold mining activities.

Illegal mining impacts on freshwater Potamonautid crab in a subtropical Austral highland biosphere reserve

The contamination of surface water by heavy metals, especially mercury, has become a global issue. This problem is particularly exacerbated in rivers and reservoirs situated in developing nations. Therefore, the objective of this study was to evaluate the potential contamination effects of illegal gold mining activities on freshwater Potamonautid crabs and to quantify the mercury levels in 49 river sites under three land use classes: communal areas, national parks and timber plantations. We used a combination of field sampling, multivariate analysis and geospatial tools to quantify mercury concentrations in relation to crab abundances. Illegal mining was prevalent throughout the three land use classes, with mercury (Hg) being detected in 35 sites (71.5 %). The mean range of Hg concentrations detected across the three–land uses was: communal areas 0–0.1 mg kg−1, national parks 0–0.3 mg kg−1 and timber plantations 0–0.06 mg kg−1. Mean Hg geo–accumulation index values showed strong to extreme contamination in the national park, with strong contamination observed for communal areas and timber plantations; furthermore, the enrichment factor for Hg concentrations in the communal and national park areas showed extremely high enrichment. Two crab species (i.e., Potamonautes mutareensis, Potamonautes unispinus) were found in the Chimanimani area, with P. mutareensis being the dominant taxon in the region across all the three land use areas. The national parks had higher total crab abundances than communal and timber plantation areas. We observed negative and significant K, Fe, Cu and B effects on total Potamonautid crab abundances, but surprisingly not for other metals such as Hg which might reflect their widespread pollution. Thus, illegal mining was observed to impact the river system, having a serious impact on the crab abundance and habitat quality. Overall, the findings of this study underscores the need to address the issue of illegal mining within the developing world as well as to establish concerted effort from all stakeholders (e.g., government, mining companies, local communities, and civil society groups) to help protect the less charismatic and understudied taxa. In addition, addressing illegal mining and protecting understudied taxa aligns with the SDGs (e.g. SDG 14/15-life below water/life on land) and contributes to global efforts to safeguard biodiversity and promote sustainable development.

Investigating Landfill Leachate and Groundwater Quality Prediction Using a Robust Integrated Artificial Intelligence Model: Grey Wolf Metaheuristic Optimization Algorithm and Extreme Learning Machine

The likelihood of surface water and groundwater contamination is higher in regions close to landfills due to the possibility of leachate percolation, which is a potential source of pollution. Therefore, proposing a reliable framework for monitoring leachate and groundwater parameters is an essential task for the managers and authorities of water quality control. For this purpose, an efficient hybrid artificial intelligence model based on grey wolf metaheuristic optimization algorithm and extreme learning machine (ELM-GWO) is used for predicting landfill leachate quality (COD and BOD5) and groundwater quality (turbidity and EC) at the Saravan landfill, Rasht, Iran. In this study, leachate and groundwater samples were collected from the Saravan landfill and monitoring wells. Moreover, the concentration of different physico-chemical parameters and heavy metal concentration in leachate (Cd, Cr, Cu, Fe, Ni, Pb, Mn, Zn, turbidity, Ca, Na, NO3, Cl, K, COD, and BOD5) and in groundwater (Cd, Cr, Cu, Fe, Ni, Pb, Mn, Zn, turbidity, EC, TDS, pH, Cl, Na, NO3, and K). The results obtained from ELM-GWO were compared with four different artificial intelligence models: multivariate adaptive regression splines (MARS), extreme learning machine (ELM), multilayer perceptron artificial neural network (MLPANN), and multilayer perceptron artificial neural network integrated with grey wolf metaheuristic optimization algorithm (MLPANN-GWO). The results of this study confirm that ELM-GWO considerably enhanced the predictive performance of the MLPANN-GWO, ELM, MLPANN, and MARS models in terms of the root-mean-square error, respectively, by 43.07%, 73.88%, 74.5%, and 88.55% for COD; 23.91%, 59.31%, 62.85%, and 77.71% for BOD5; 14.08%, 47.86%, 53.43%, and 57.04% for turbidity; and 38.57%, 59.64%, 67.94%, and 74.76% for EC. Therefore, ELM-GWO can be applied as a robust approach for investigating leachate and groundwater quality parameters in different landfill sites.

Seasonal variation in non-point source heavy metal pollution in Satpara Lake and its toxicity in trout fish.

Heavy metal contamination in surface water is widespread throughout the world as a result of numerous anthropogenic activities and geo-genic mechanisms. This contamination is also affecting aquatic life, as fish have the potential to acquire heavy metals in their tissues making them vulnerable. Worldwide lakes are an important source of water for the inhabitants of the area. So, in the present study, we have focused on the Satpara Lake to check the extent of heavy metal pollution and their accumulation in fish to provide baseline data for metal pollution management. Samples were collected from three locations (inflow, center, and outflow sites) during two seasons (summer and winter). Inductively coupled plasma optical emission spectrometry (ICP-OES) was applied to analyze heavy metals concentration. Among the metals, Cd, Pb, As, and Fe revealed relatively higher concentrations. The highest concentration of heavy metal found in water and fish was of Cd, i.e., 8.87mg L-1 and 18.19mg L-1 in summer season, respectively. Arsenic concentration was also higher than the permissible limits in both water (0.76) and fish (1.17mg L-1). The water quality assessment showed that in the summer season, the HPI (heavy metal pollution index) value 253.01 was more than 100, indicating the bad quality of water for drinking purposes. However, the HPI value 35.72 was less than 100 in winter. Toxicity hazard calculation of fish in summer seasons gives Hi values greater than 10.0, indicating the acute effect on human health as compared to winter.

Interaction of Microbes with Microplastics and Nanoplastics in the Agroecosystems-Impact on Antimicrobial Resistance.

Microplastics (MPs) and nanoplastics (NPs) are hotspots for the exchange of antimicrobial resistance genes (ARGs) between different bacterial taxa in the environment. Propagation of antimicrobial resistance (AMR) is a global public health issue that needs special attention concerning horizontal gene transfer (HGT) under micro-nano plastics (MNPs) pressure. Interactions between MNPs and microbes, or mere persistence of MNPs in the environment (either water or soil), influence microbial gene expressions, affecting autochthonous microbiomes, their resistomes, and the overall ecosystem. The adsorption of a range of co-contaminants on MNPs leads to the increased interaction of pollutants with microbes resulting in changes in AMR, virulence, toxin production, etc. However, accurately estimating the extent of MNP infestation in agroecosystems remains challenging. The main limitation in estimating the level of MNPs contamination in agroecosystems, surface and subsurface waters, or sediments is the lack of standardized protocols for extraction of MPs and analytical detection methods from complex high organic content matrices. Nonetheless, recent advances in MPs detection from complex matrices with high organic matter content are highly promising. This review aims to provide an overview of relevant information available to date and summarize the already existing knowledge about the mechanisms of MNP-microbe interactions including the different factors with influence on HGT and AMR. In-depth knowledge of the enhanced ARGs propagation in the environment under the influence of MNPs could raise the needed awareness, about future consequences and emergence of multidrug-resistant bacteria.

Revealing the effect of an industrial flash flood on vegetation area: A case study of Khusheh Mehr in Maragheh-Bonab Plain, Iran

Floods are one of the most significant environmental hazards that can have harmful effects on agricultural activities and vegetation. The primary objective of this study is to analyze the destructive after-effects of an industrial flash flood on the vegetation of the Khusheh Mehr region. This flash flood occurred due to a break in the wastewater ponds of the Kaveh Soda factory on April 25, 2010. Using the Normalized Difference Water Index (NDWI) and the Normalized Difference Vegetation Index (NDVI) derived from time-series Landsat data over the period of 2000–2020, we analyzed the changes in wastewater ponds and regional vegetation before and after the wastewater flood occurred. We also investigate the quantitative and qualitative changes in vegetation during the past 20 years and detect the flood passage through this area. The results show that 538 ha out of the total 2123 ha of Khusheh Mehr were directly affected by the runoff resulting from the 2010 flood, and 1250000 m3 of industrial wastewater was discharged in the study area. The analysis of the vegetation in 2010 showed that during May and July, the efficiency and expansion of vegetation in these areas (NDVI >0.3) decreased by 90% and 55%, respectively, compared to the same periods in 2009 and 2006. The study is significant because it can help evaluate the effects of the flash flood not only on wastewater ponds and vegetation but also on the contamination of underground and surface waters as chemicals and industrial wastewater held in natural and artificial environments are discharged during a flood and directly affect vegetation. The findings can provide useful information for hazard and land use management and support policymakers, e.g., payment for financial loss of farmers.

Physiochemical and Microbiological Investigation of Surface and Ground Water Contaminants of Bhojpur Municipality

Water is an essential resource for life evolution. 75% of the whole earth is covered by water. The water sources that flow through the social periphery represent the development and awareness of that society. This paper focuses on investigating contaminants of different water sources within Bhojpur Municipality. The six different water samples, based on their different latitudes, were collected following all the guidelines. The physiochemical parameters and microbiological organisms like E. Coli were tested and analyzed. The results revealed that the physiochemical parameters were mostly found to be within the guideline and standardization of the World Health Organization (WHO), but in the Silichung water sample, the number of bacteria was found to be out of the WHO limit. Physiochemical parameters like total dissolved solids (TDS), total solids (TS), and chloride content were not found under the guideline of WHO. The dissolved oxygen (DO) content was found more in the water sample of Bahundhara, whereas Bhandari well sample had a low amount of DO among the other samples. The biological oxygen demand (BOD) level in Sera Khola sample was found more, while Silichung sample had a low amount of BOD, indicating Sera Khola water sample is a bit more polluted than others. On microbiological testing, the Silichung water sample was tested with Providencia spp, indicating not useful for drinking purposes. Thus, it reveals that the Silichung water should not take directly, which is rich in Providencia spp. Other physiochemical parameters of other samples were found to be within the range of WHO.

Uptake of 15N-urea and phosphates in Triticum aestivum with Pseudomonas putida and Rhizophagus irregularis endophytes of calcareous soil weeds

In calcareous soil, the growth and production of _Triticum aestivu_m depends on the availability of phosphates, which in turn reduces the uptake of nitrogen in the form of urea, which causes volatilization and partial leaching of both fertilizers, contributing to the greenhouse effect, and warming global. An alternative ecological solution for _T. aestivum _is to inoculate _Pseudomonas putida _and_ Rhizophagus irregularis_ with endophytes that increase phosphorus uptake such as P2O5 and urea. The objective of this research was to analyze the uptake and distribution of 15N-urea in _T. aestivum_ with _P. putida _and _R. irregularis_ fertilized with 50% urea and P2O5. In this sense, _P. putida _and_ R. irregularis_ isolated from roots of _Resenda luteola _and_ Arista purpurea_ native to the calcareous soil of northeastern Mexico. In_ T. aestivum_ with these endophytes, acid and alkaline phosphatase activity in root and stem, N (nitrogen) uptake from total urea (Nt) and yield (Y). The experimental data were analyzed by ANOVA/Tukey (P&lt;0.01). The results showed a positive response of _T. aestivum to P. putida _and _R. irregularis_ with 60 kg/ha of urea and 40 kg/ha of P2O5, equivalent to the 50% recommended for this region of Mexico. It was evidenced that in _T. aestivum, P. putida, _and _R. irregularis _endophytes of desert weeds improved the uptake of urea and P2O5 to 50% by phytohormones that optimized nitrogen with phosphatases, soil phosphate and that from the applied fertilizer. The Nt in stem and the yield of _T. aestivum _with_ P. putida and R. irregularis_ reached statistically different numerical values to those registered in _T. aestivum _with 120 kg/ha of urea and 80 kg/ha of P2O5 without _P. putida _and_ R. irregularis _at 100% (relative control), consequently the performance of _T. aestivum_ in calcareous soils. It is avoided by the generation of greenhouse gases, the contamination of surface water, by using the beneficial interaction of endophytes with weeds with _T. aestivum,_ as well as global warming.

Degradation of crude oil by the microbial populations of Lagos and Ologe lagoon waters

Introduction: hydrocarbon contamination of surface waters as a result of anthropogenic activity poses threat to ecosystems and counter their beneficial uses. Some indigenous microbial communities have the potential to purify such waters unaided. Aims: To show the biodegradative potential of microbial communities in Lagos and Ologe Lagoons during minimal pollution with crude oil. Materials and Methods: The total heterotrophic bacteria and hydrocarbon utilising bacterial and fungal populations were estimated from Lagos and Ologe lagoon water samples contaminated with 1% crude oil over 42-day incubation period by plate count and vapour-phase transfer techniques. Residual hydrocarbons were determined by Gas chromatography. Results: The predominant bacterial genera identified from the lagoons include Enterobacter, Klebsiella and Proteus, while Escherichia, and Morganella. Aspergillus and Mucor were the predominant fungal genera in both waters. The hydrocarbon degradation rate in the Lagos Island microcosm was 65.391±0.370 mg/l/d, degradation rate constant 0.05±0.01 /d, half-life 9.559±0.093 /d and percentage degradation of 95.315 ± 0.134. Corresponding values in the Ologe water were 61.190± 8.542 mg/l/d, 8.725 ±0.389 /d, 0.055±0.003/d and 96.345±0.488 respectively. There was almost complete disappearance of the various fractions of the oil in the two samples. The microbial communities from both lagoons effectively utilised majority of the hydrocarbon fractions after 42 days where 66.890±1.075 and 100±000 were recorded for benzene, toluene had 100±000 percent degradation, anthracene 96.755±0.119 and 99.726±0.026, and pristane had 91.674±0.222 and 99.943±0.015 while phytane had 96.44±0.058 and 99.670±0.104 respectively. Conclusion: Efficient biodegradation of moderate contamination crude oil could be achieved by indigenous microbial flora present in Lagos and Ologe lagoon waters.

Overlooked Transformation of Nitrated Polycyclic Aromatic Hydrocarbons in Natural Waters: Role of Self-Photosensitization.

Photochemical transformation is an important process that involves trace organic contaminants (TrOCs) in sunlit surface waters. However, the environmental implications of their self-photosensitization pathway have been largely overlooked. Here, we selected 1-nitronaphthalene (1NN), a representative nitrated polycyclic aromatic hydrocarbon, to study the self-photosensitization process. We investigated the excited-state properties and relaxation kinetics of 1NN after sunlight absorption. The intrinsic decay rate constants of triplet (31NN*) and singlet (11NN*) excited states were estimated to be 1.5 × 106 and 2.5 × 108 s-1, respectively. Our results provided quantitative evidence for the environmental relevance of 31NN* in waters. Possible reactions of 31NN* with various water components were evaluated. With the reduction and oxidation potentials of -0.37 and 1.95 V, 31NN* can be either oxidized or reduced by dissolved organic matter isolates and surrogates. We also showed that hydroxyl (•OH) and sulfate (SO4•-) radicals can be generated via the 31NN*-induced oxidation of inorganic ions (OH- and SO42-, respectively). We further investigated the reaction kinetics of 31NN* and OH- forming •OH, an important photoinduced reactive intermediate, through complementary experimental and theoretical approaches. The rate constants for the reactions of 31NN* with OH- and 1NN with •OH were determined to be 4.22 × 107 and 3.95 ± 0.01 × 109 M-1 s-1, respectively. These findings yield new insights into self-photosensitization as a pathway for TrOC attenuation and provide more mechanistic details into their environmental fate.

Treatment of Synthetic Industrial Effluent Aiming at the Removal of Glyphosate by Means of Advanced Oxidation

Objective: The purpose of this study was to assess the efficiency of an advanced oxidative process gradually applying different oxidative agents, i. e. UV, TiO2 and O3, to evaluate the removal efficiency of a commercial composition of glyphosate from an aqueous matrix. Theoretical framework: In Brazil, approximately 150 million liters of glyphosate are consumed per year, representing 30% of the total pesticides used, which can contaminate surface water due to aerial or terrestrial spraying, erosion and runoff, improper disposal of commercial packaging and cleaning of contaminated spray tanks. Advanced oxidative processes have emerged as an alternative to the degradation of glyphosate since they have high efficiency in reducing organic contaminants to an acceptable limit with a low operating cost. Method: Experimental consisted of a benchtop-scale system, composed of a batch reactor with a 25W UV lamp inside and a feeding pump in a recirculation reservoir. It was responsible for performing the removal of glyphosate by means of an advanced oxidative process after receiving TiO2 and O3 application. Results and conclusion: The photolysis process obtained an efficiency of 24.69%, the photocatalytic oxidation process with TiO2 obtained 37.78%, and the photocatalytic ozonation with TiO2 obtained 45.46% efficiency in 60 minutes of reaction. The possible formation of byproducts after one hour of reaction due to the increase in concentration was also observed, since it was not possible to distinguish glyphosate from other compounds in the analysis method applied. Implications of the research: As demonstrated by the results of the experimental assays, the advanced oxidative technique proved to be very efficient to make the removal of a commercial composition of glyphosate from an aqueous matrix. Originality/value: It has been shown that it is possible to remove glyphosate in an efficient way, using a highly efficient fast technique.

Grafted polymeric organogel using low molecular weight gelator as an effective medium for expulsion and purification of cationic dyes and organic pollutants from contaminated surface water

An increase in water pollution is a major concern for the safety of living organisms. The present work revolves around synthesizing an organogel capable of absorbing contaminated pollutants like solvents and removing cationic dyes from water surfaces. The organogel prepared using a LMWG (low molecular weight gelator) was characterized using FT-IR, SEM, NMR, TGA, and XRD spectra. Water contact angle determination was also carried out to observe the hydrophobicity. Swelling kinetics, adsorption isotherm, and intra-particle diffusion model are reported after the respective absorption and adsorption study by the gel. The highest swelling was observed in Acetic acid with swelling of 10 times its original weight. Adsorption of dyes exhibited the highest removal efficiency of 99.35% within 60 min. The organogel holds the capability to reuse dye solutions for up to 10 cycles while also holding the capacity to remove from a binary mixture of dyes. The prepared organogel serves as a potential adsorbent for environmental remediation with the potential of maximum swelling and selectivity for cationic dyes.

Developing a Slow-Release Permanganate Composite for Degrading Aquaculture Antibiotics

Copious use of antibiotics in aquaculture farming systems has resulted in surface water contamination in some countries. Our objective was to develop a slow-release oxidant that could be used in situ to reduce antibiotic concentrations in discharges from aquaculture lagoons. We accomplished this by generating a slow-release permanganate (SR-MnO4−) that was composed of a biodegradable wax and a phosphate-based dispersing agent. Sulfadimethoxine (SDM) and its synergistic antibiotics were used as representative surrogates. Kinetic experiments verified that the antibiotic-MnO4− reactions were first-order with respect to MnO4− and initial antibiotic concentration (second-order rates: 0.056–0.128 s−1 M−1). A series of batch experiments showed that solution pH, water matrices, and humic acids impacted SDM degradation efficiency. Degradation plateaus were observed in the presence of humic acids (&gt;20 mgL−1), which caused greater MnO2 production. A mixture of KMnO4/beeswax/paraffin (SRB) at a ratio of 11.5:4:1 (w/w) was better for biodegradability and the continual release of MnO4−, but MnO2 formation altered release patterns. Adding tetrapotassium pyrophosphate (TKPP) into the composite resulted in delaying MnO2 aggregation and increased SDM removal efficiency to 90% due to the increased oxidative sites on the MnO2 particle surface. The MnO4− release data fit the Siepmann–Peppas model over the long term (t &lt; 48 d) while a Higuchi model provided a better fit for shorter timeframes (t &lt; 8 d). Our flow-through discharge tank system using SRB with TKPP continually reduced the SDM concentration in both DI water and lagoon wastewater. These results support SRB with TKPP as an effective composite for treating antibiotic residues in aquaculture discharge water.

Seasonal pulse effect of microplastics in the river catchment-From tributary catchment to mainstream

Rivers have received extensive attention as a major pathway for microplastics (<5000 μm) from land to ocean. This study investigated the seasonal variation of microplastic contamination in surface water of the Liangfeng River catchment, a tributary of the Li River in China, based on a fluorescence-based protocol, and further explored the migration process of microplastic in the river catchment. The abundance of microplastics (50–5000 μm) was (6.20 ± 0.57)–(41.93 ± 8.13) items/L, of which 57.89–95.12% were small-sized microplastics (<330 μm). The microplastic fluxes in the upper Liangfeng River, lower Liangfeng River, and upper Li River were (14.89 ± 1.24) × 1012, (5.71 ± 1.15) × 1012, and (1.54 ± 0.55) × 1014 items/year, respectively. The 3.70% of microplastic load in the mainstream came from the tributary input. Fluvial processes can effectively retain 61.68% of microplastics in the surface water of river catchments, especially for small-sized microplastics. The rainy season is the main period of microplastic retention (91.87%) in the tributary catchment by fluvial processes, while exporting 77.42% of one-year microplastic emissions from the tributary catchment into the mainstream. This study is the first to reveal the transport characteristics of small-sized microplastics in river catchments based on flux variation, which not only can partly explain the “missing small-sized microplastic fraction” in the ocean, but also contribute to improving microplastic model.