Freshwater Pollution Research Articles

Migration patterns, habitat use and genetic origins of sea trout (Salmo trutta) in Norfolk chalk streams: implications for management of a mixed stock fishery

Sea trout, the anadromous ecotype of the species Salmo trutta, are subject to multiple threats, including exploitation and aquaculture impacts in the marine environment, habitat fragmentation and pollution in freshwaters, loss of genetic resilience due to interbreeding with hatchery strains and environmental change. Small streams contribute relatively little biomass to European sea trout stocks but are thought to be important in maintaining genetic diversity and therefore wider population resilience. The current study combined data from acoustic telemetry, stable isotopes, genetics and scalimetry to assess the current status of sea trout in the rivers Stiffkey and Glaven, two locally important chalkstreams in East Anglia, UK, to provide an evidence base for future management. The incidence of anadromy was low, and most sea trout were near migrants, residing in the lower reaches of rivers and close to the tidal outfalls. A small number migrated to the North Sea where they were vulnerable to exploitation in the coastal fishery, which comprises a mixed stock. Straying between the two rivers was recorded among 10% of sea trout, leading to apparent high gene flow. Nonetheless, genetic data also demonstrated structuring of River Glaven trout into two distinct groups. Quantification of patterns of freshwater and estuarine habitat use, and of passage at cross-channel obstructions, was used to identify where remedial measures such as habitat restoration would be most effectively targeted. Findings are discussed in the context of local supplementary stocking and the potential impact of the nearshore fishery on limited and vulnerable small stream anadromous trout populations.

Microplastic contamination in the Aquaculture Icon Oreochromis mossambicus: Prevalence, Characteristics, and Comprehensive Overview.

The global production of plastics has surged to 368 million tonnes annually, leading to significant plastic waste accumulation, projected to reach 12,000 Mt by 2050, impacting aquatic ecosystems. Fish, crucial for their protein and nutrients, are particularly vulnerable to microplastic (MP) ingestion. As a major aquaculture producer and fish consumer, India faces rising plastic pollution in freshwater, which disrupts fish health and growth, posing a significant threat to the sustainability and productivity of aquaculture systems and potential health risks. This study focuses on Mozambique tilapia (Oreochromis mossambicus), valued for its widespread aquaculture use, rapid growth, and nutritional benefits. Our research reveals significant MP contamination (69.23%) in Mozambique tilapia, with over 80% from the Ulhas River and 60% from the Bhima River contaminated and females showing higher susceptibility. These findings emphasise the need for further research on MP impacts on human health and the development of mitigation strategies.

Managing phosphorus input pressures for improving water quality at the catchment scale

Phosphorus (P) pollution of freshwater is an endemic threat to water quality and aquatic biodiversity. To better define the contributions of the two main food system sectors (agriculture and wastewater) responsible for freshwater P pollution, we investigated how the magnitude and distribution of sector P input pressures calculated using Substance Flow Analysis (SFA) linked to the P pollution threat across four distinct physiographic regions of the River Stour catchment (1260 km2) in Dorset, England. Agricultural P input pressures (−1 to 7 kg ha−1 yr−1) were dependent on the amount of livestock feed imports and resulting manure loadings to land, whilst food imports and population densities were the main driver of the human net P inputs of up to 13 kg ha−1 yr−1. Total P input pressures (i.e. Net Anthropogenic P Inputs (NAPI)) were positively correlated (r2 0.8–0.9) to riverine P flux of up to 6 kg ha−1 yr−1 across the catchment. Using measured river P concentration (C) and flow discharge (Q) analysis to distinguish monitoring stations capturing mainly diffuse P sources (termed diffuse stations), estimated riverine P fluxes attributable to agriculture varied up to 0.92 kg ha−1 yr−1 depending on the surplus P inputs applied to land. A combination of enhanced wastewater P removal and reduced surplus agricultural P inputs was required to improve water quality. For example, the P pressure-river P flux relationship at diffuse stations suggested that in the catchment area dominated by livestock production, removing the agricultural P surplus of 7 kg ha−1 yr−1 would reduce annual average river SRP concentrations in this area by a third to 0.23 mg L−1, but still well above the target concentration for eutrophication control (0.08 mg L−1). Our approach of linking SFA outputs to measured river P data provides a potential complimentary and internationally relevant methodology to evidence effective sector mitigation targets and policies in catchments, and its further testing in other catchments is recommended.

Alien aquatic plants in Poland: Temporal and spatial distribution patterns and the effects of climate change

Distribution of alien aquatic plants in European freshwater ecosystems is still not fully recognized. Little is also known about the impact of climatic factors on the expansion of particular neophyte species in freshwater ecosystems. In this article, we present the first comprehensive assessment of the occurrence of non-native aquatic vascular plants in Poland (CE Europe), with a particular focus on: (1) inventory of the species, (2) temporal and spatial changes in their distribution, and (3) the climate impact on species occurrence and diversity. For this purpose, we collected both published and unpublished data on alien macrophytes occurrence in Poland covering past 70 years. In order to investigate the mechanism of alien aquatic plant expansion, climate data from 24 meteorological stations were analyzed. Redundancy analysis (RDA) was used to analyze the relationship between species composition and microclimate variables. In addition, Generalized Additive Model (GAM) was used to examine the response curves of neophyte species to temperature parameters.In total, we found records of 15 neophytes of alien aquatic plant taxa in Poland, including 14 species and collective taxon of Nymphaea cultivars. The most frequent was Elodea canadensis (over 25,000 records). Excluding this species, we counted more than 300 records of the occurrence of alien aquatic plants, of which three (E. nuttallii, Azolla filiculoides and Lemna turionifera) were the most abundant. Ten species occurred only in isolated sites. In addition, analyses showed a substantial increase in the number of the aquatic neophyte sites in the last 20 years that could be linked with the raised average monthly and yearly air temperatures in Poland.Our results showed a strong relationship between raised average temperatures in Poland and the spread of some species, e.g. Azolla filiculoides, while other species such as Elodea nuttallii and Lemna turionifera expanded irrespectively of this factor. The occurrence of some species (e.g. Vallisneria spiralis, Hygrophila polysperma) was exclusively associated to high thermally altered or thermally contaminated waters, and thus was limited to only a small part of the country. Our results confirm the major role of elevated temperatures (mean annual temperatures and minimum monthly temperatures) and thermally polluted freshwater ecosystems in the distribution of alien aquatic plants.

Effect of Wastewater Irrigation on Yield, Water Productivity and Economics of Sunflower and Toria Crop

Water scarcity is one of the most important issue affecting the global economy and human livelihoods. Climate change, rapid population growth, freshwater pollution and depletion are among the factors exacerbating the situation. Although not yet fully exploited, wastewater reclamation and reuse are considered potential mechanisms to mitigate the challenge. To evaluate the impact of wastewater on yield, economics, soil nutrient status, seed oil content and water productivity, a two-year experiment at farmers field in Angul, Odisha was taken up. The sunflower yield was found significantly higher with wastewater irrigation (10%) which was mainly contributed by higher head diameter (15.3 cm), no. of achenes per head (467) and 100 achene weight (69g). Similarly, toria crop irrigated with wastewater had higher yield by 11% resulting from higher siliquae per plant (179), no of seeds per siliqua (12.1) and test weight (4.6) compared to freshwater irrigation. Besides this soil nutrients and oil content was higher in wastewater irrigated toria and sunflower crop than freshwater crops. Benefit cost ratio was higher in wastewater irrigated sunflower (3.9) and toria (2.0) crop compared to freshwater irrigated crops (3.0 and 1.4 respectively for sunflower and toria). Water productivity under wastewater irrigation in sunflower (0.38 kg/m3) and toria (0.21 kg/m3) was higher than freshwater irrigated crops by 10-12%. The findings of the present study suggest that wastewater can be used as a source of irrigation for oilseed crop in Angul Odisha where water scarcity is acute during rabi season.

Adsorption of toxic metals from greywater using coconut husk biochar and spent green tea

The discharge of wastewater into ground and surface waters can cause human and ecological health problems, hence eco-friendly, sustainable and cost-effective methods for removing toxic metals from wastewater are required. The study employed coconut husk biochar and spent impra ginseng flavoured green tea to adsorb cadmium (Cd), chromium (Cr) and lead (Pb) from greywater. The adsorption capacity of coconut husk biochar ranged from 88.70 % to 98.20 % for cadmium, 78 %–96 % for chromium and 95.71 %–99.29 % for lead whilst the spent impra ginseng flavoured green tea ranged from 94.03 % to 96.87 % for cadmium, 52 %–74 % for chromium and 98.52 %–99.48 % for lead. The maximum adsorption capacity (Qe) of coconut husk biochar ranged from 235.64 to 1132.40 mg/g for Cd, 1.31–8.80 mg/g for Cr and 58.85–415.80 mg/g for Pb. Lead demonstrated the highest affinity for the binding of coconut husk biochar and spent impra ginseng flavoured green tea adsorbent with a trend of Pb > Cd > Cr. Coconut husk biochar and spent impra ginseng flavoured green tea adsorbent were suitable for the toxic metals adsorption in the greywater. Cr showed different removal efficiencies where coconut husk biochar showed more effective removal than spent impra ginseng flavoured green tea. The application of coconut husk biochar and spent impra ginseng flavoured green tea in wastewater treatment is a green technology means and can lead to zero pollution of freshwater.

Distribution, flux, and risk assessment of microplastics at the Anzali Wetland, Iran, and its tributaries.

Microplastic pollution has raised significant concerns among scientific communities and society in recent years due to its increase and lesser-known effects on the environment. To improve the knowledge of microplastic pollution in freshwater, we investigated microplastics in Anzali Wetland, a Ramsar site in northern Iran, as well as its nine main entering rivers. The extracted microplastics were characterized via visual identification, SEM-EDX, and μ-Raman methods. Microplastics (size range: 50-5000 μm) were found in all water and sediment samples with concentration of fibrous particles as well as polypropylene and polyethylene polymers. The mean concentration of microplastics in bottom sediment and surface water samples of the wetland was 301 ± 222 particles∙kg-1 d.w. and 235 ± 115 particles∙m-3 (0.23 particles∙L-1), respectively. The microplastic concentration in the central and eastern parts of the wetland was higher than in other areas; however, the mean concentrations revealed homogeneity across the wetland area. Water properties (dissolved oxygen, pH, temperature, electrical conductivity, and salinity in water) did not affect the concentration of microplastic particles, though correlational analysis revealed a strong positive association between microplastic quantity and turbidity. There was a significant positive relationship between microplastic concentration and the percentage of clay in sediment samples. The quantity of microplastics in river water was higher than in wetland water, but the difference between the results was not significant. However, the quantity of microplastics in the river's littoral sediment was higher than in the bottom sediment of the wetland where the difference between the results was significant. Microplastic ecological risk assessment showed high potential ecological risk. The findings underscore the importance of effective management strategies and the implementation of policies to mitigate the negative impact of MP pollution on ecosystems and human health.

Biomonitoring of Heavy Metal Toxicity in Freshwater Canals in Egypt Using Creeping Water Bugs (Ilyocoris cimicoides): Oxidative Stress, Histopathological, and Ultrastructural Investigations.

The abundance of metal pollutants in freshwater habitats poses serious threats to the survival and biodiversity of aquatic organisms and human beings. This study intends for the first time to assess the pernicious influences of heavy metals in Al Marioteya canal freshwater in Egypt, compared to Al Mansoureya canal as a reference site utilizing the creeping water bug (Ilyocoris cimicoides) as an ecotoxicological model. The elemental analysis of the water showed a significantly higher incidence of heavy metals, including cadmium (Cd), cobalt (Co), chromium (Cr), nickel (Ni), and lead (Pb), in addition to the calcium (Ca) element than the World Health Organization's (WHO) permitted levels. The Ca element was measured in the water samples to determine whether exposure to heavy metals-induced oxidative stress engendered Ca deregulation in the midgut tissues of the creeping water bug. Remarkably, increased levels of these heavy metals were linked to an increase in chemical oxygen demand (COD) at the polluted site. Notably, the accumulation of these heavy metals in the midgut tissues resulted in a substantial reduction in antioxidant parameters, including superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and ascorbate peroxidase (APOX), along with a marked rise in malondialdehyde (MDA), cytochrome P450, and protein carbonyl levels. These results clearly indicate a noticeable disturbance in the antioxidant defense system due to uncontrollable reactive oxygen species (ROS). Notably, the results demonstrated that oxidative stress caused disturbances in Ca levels in the midgut tissue of I. cimicoides from polluted sites. Furthermore, the comet and flow cytometry analyses showed considerable proliferations of comet cells and apoptotic cells in midgut tissues, respectively, exhibiting prominent correlations, with pathophysiological deregulation. Interestingly, histopathological and ultrastructural examinations exposed noticeable anomalies in the midgut, Malpighian tubules, and ovarioles of I. cimicoides, emphasizing our findings. Overall, our findings emphasize the potential use of I. cimicoides as a bioindicator of heavy metal pollution in freshwater to improve sustainable water management in Egypt.

Microplastics in wild fish in the Three Gorges Reservoir, China: A detailed investigation of their occurrence, characteristics, biomagnification and risk

Microplastics (MPs) pollution in freshwater poses a risk to various ecosystems and health security. In 2018, the Chinese government banned fishing since 2018 in the Three Gorges Reservoir (TGR), but the fate and risk of MPs in wild fish remain unclear. Therefore, a detailed investigation was conducted into the occurrence of MPs in 18 wild fish species in the TGR using a Micro Fourier Transform Infrared Spectrometer, and the trophic transfer and risks were assessed. MPs in fish were aged, with abundances ranging from 0.68 ± 0.98 to 4.00 ± 2.12 items/individual. Most particles were less than 1 mm in size (73.4 %), with fibers being the dominant shape (48.9 %) and transparent as the dominant color (35 %). Polyethylene (PE) was the most prevalent type. The bioconcentration factor (BCF), bioaccumulation factor (BAF), trophic magnification factor (TMF) and polymer hazard index (PHI) were low, suggesting no trophic transfer and a low risk of MPs. The BAF may provide a more reasonable description of the degree of enrichment of MPs, and ‘items/individual’ or ‘g/individual’ can be used to describe MPs concentrations in fish. This study proposes new insights and prospectives that can help researchers better understand MPs enrichment in fish across various trophic levels.

Water, environment, and health nexus: understanding the risk factors for waterborne diseases in communities along the Tano River Basin, Ghana.

Freshwater pollution is a major concern in Ghana, directly impacting human health. However, the underlying drivers of exposure and risks are not comprehensively understood, emphasizing the severity and impact of these diseases. This study assessed the interaction between water and human health, specifically focusing on the risk factors for waterborne diseases and the drivers of water pollution among residents near the Tano River Basin, Ghana. A sample size of 400 households was selected from five communities within the basin based on their proximity to the Tano River. In addition, the study combined both spatial and non-spatial data sources to map potential flood zones for the basin. The study found that inadequate sanitation, poor hygiene practices, and contamination from illegal mining were the primary causative factors of waterborne diseases. Additionally, floods and improper waste management significantly contributed to disease outbreaks. The flood susceptibility analysis indicated that areas highly susceptible to flooding cover 21.2% of the basin, predominantly in the southern part. The results highlight the urgent need for comprehensive interventions to address the drivers of waterborne diseases. This study will contribute to the local authorities in developing plans to prevent waterborne diseases and mitigate their economic and public health impacts.

Влияние фосфорсодержащих пестицидов на ферментативную активность и множественные формы кислой фосфатазы живородки речной (Viviparus viviparus L.)

Organophosphate pesticides are used in agriculture and for treating landscape and park areas due to their high efficiency and economic availability, and therefore they are potential toxicants in water bodies. Broad-spectrum systemic herbicide (Glyphosate) and an organophosphorus insecticide (Malathion) have been studied against the freshwater mollusks (Viviparus viviparus L.), widespread in permanent water bodies of the European part of Russia and Siberia. Changes in the activity and composition of multiple forms of acid phosphatase (AcP) were revealed in the hepatopan creas of mollusks under the influence of high doses of glyphosate and malathion in an acute toxicological experiment (96 hours). In both cases, an increase in enzyme activity is observed, but the cholinomimetic malathion is significantly more active than glyphosate, the neurotropic activity of which is unknown. It was shown that the increase in activity in the experimental groups of mollusks is associated with the appearance of new multiple forms of acid phosphatase, which persist throughout the experiment. Multiple form of AсP with low relative electrophoretic mobility revealed as an effect of glyphosate and malathion. In addition, in mollusks exposed to malathion, a multiple form of the enzyme with an average electrophoretic mobility was detected. The composition of multiple forms of acid phosphatase in mollusks of the control group did not change during the exposure. The results indicate the formation of nonspecific adaptations in response to organophosphate pesticides and confirm that acid phosphatase can be an indicator of toxic effects in environmental and biochemical monitoring of freshwater pollution.

Microplastics in Russian Freshwater Systems: a Review

Contamination of environment by plastic debris has already become a worldwide problem due to the global production of polymers and the further accumulation of waste. Microplastic particles (<5 mm) have been found almost everywhere. Despite the significant number of publications devoted to the microplastic pollution in freshwater and marine environments, in the review articles around the world freshwater systems the Russian territory is a white spot. The article provides the summary of studies investigating microplastics (MP) in Russian lakes and rivers, the determination of concentrations, type and composition of polymer particles and also possible sources of plastic contamination. The map of the MP distribution in Russian freshwater systems is presented. The concentration of microplastics in freshwater system varies greatly, e.g., in lakes from 0,27 items/m3 in Lake Baikal to (4-26)∙103 items/m3 in the Altai lakes of Western Siberia; in large Russian rivers measured polymer content varies by three orders of magnitude, from parts of items/m3 in the Volga River to hundreds of items/m3 in the Upper Ob. Significantly higher concentrations of MP are found in the bottom sediments of rivers and lakes, exceeding polymer concentrations in surface water by several orders of magnitude. Thus, bottom sediments are able to accumulate significant amounts of MP.

How plastic waste management affects the accumulation of microplastics in waters: a review for transport mechanisms and routes of microplastics in aquatic environments and a timeline for their fate and occurrence (past, present, and future)

An increasing global problem is the buildup of improperly handled plastic garbage in the environment. One of the biggest environmental issues facing aquatic ecosystems today is contamination from bulk plastics and plastic detritus. Specifically, microplastics (MPs) and nanoplastics, which are small-scale plastic waste, are now the main causes of pollution in freshwater and marine environments. On the other hand, contamination of aquatic systems is now acknowledged as one of the major environmental hazards facing our world. Currently, concerns have been raised regarding the breakdown of plastic products into micro and nanosized particles, because of the ineffective plastic waste management. To prioritize regions for mitigation policy implementation, it is critical to pinpoint the precise MPs’ transport mechanisms and the locations where trash is created. In order to show the historical and contemporary circumstances as well as forecasts and scenarios of global plastic waste management from now until 2060, we used continent-level data on trash management. This study, finally, presents a potential future scenario of estimates on the destiny, transport, and occurrence of plastic waste in aquatic habitats, highlighting the different factors that trigger the transport of MPs into water and the necessity of rational management of plastic waste.

Crop grey water footprints in China: The impact of pesticides on water pollution

Agricultural water pollution is a significant challenge in China, a rapidly growing economy with a large agricultural sector. The grey water footprint (WF) is a tool for evaluating freshwater pollution. It expresses pollution in volumetric units identifying the pollutant that theoretically needs most water to be diluted to accepted water quality standards. Previous agricultural grey WF studies focused on nitrogen (N) and phosphorus (P), some studies included pesticides. This study assesses grey WFs based on N, P and 1513 pesticide combinations for twelve main crops and two crop categories in 31 Chinese provinces. Grey WFs, including the pesticide component, are far larger than estimated before, dominating total agricultural WFs (green, blue, and grey). The total grey WF of Chinese agriculture (4,900 109 m3 year−1) is determined by pesticides, while grey WFs related to N and P are 450 and 1,500 109 m3 year−1, differences of a factor of eleven and three respectively. The provinces Heilongjiang, Inner Mongolia, Hebei, Henan, and Shandong are hotspots contributing 37 % to the total grey WF. A limited number of pesticides used for maize, vegetables, fruits and potato (Mancozeb a fungicide, Acetochlor a herbicide and Cypermethrin an insecticide) dominate total grey WFs, contributing 80 % to the total grey WF. Eliminating the most polluting pesticides per category and redistributing the remaining ones with a similar function but lower grey WFs reduces national water pollution from agriculture by 64 %. Only five crops, i.e. maize, potato, soybean, rice and wheat, and the two crop categories, vegetables and fruits, contribute 94 % to this reduction. Probably grey WFs could reduce even further with a second elimination and redistribution effort. This study is the first national grey WF assessment related to pesticides in agriculture. It offers valuable insights to farmers and policymakers to enhance water quality in China and beyond.

Bifunctional titanium boron-phosphate glass containing Ag nanoparticles for the detection and photocatalysis of organic compounds

This study delves into the structural characterization of a composition comprising Ag-NPs/phosphate plasmonic glass. Additionally, it explores two applications aimed at addressing one of the numerous challenges facing the modern world. The continuous technological progress of society has led to the proliferation of chemicals in natural water sources, posing a significant threat to ecosystems due to their low concentrations, making them difficult to detect and remove. The findings presented herein showcase the potential of Ag-NPs/sodium/titanium-phosphate glasses as a promising solution for detecting and degrading organic pollutants in freshwater. To achieve this, Ag nanoparticles were integrated into the glass surface via the ion exchange method, followed by thermal treatment. Subsequently, the detection of crystal violet solutions, applied dropwise onto the sample surface, was successfully carried out using surface-enhanced Raman spectroscopy, reaching a detection limit as low as 10−6 M. Furthermore, the glass composition demonstrated heterogeneous photocatalytic properties for UV degradation of methylene blue, with enhanced photoactivity attributed to the presence of silver nanoparticles, resulting in a 111 % increase in the kinetic constant compared to unmodified glass. Thus, these newly developed Ag-NPs sodium titanium-phosphate glasses exhibit remarkable bifunctional capabilities, offering improved optical detection and efficient photodegradation of organic molecules.

Asian clam Corbicula fluminea as potential biomonitor of microplastics and metal(oid)s in a Patagonian River

This study summarizes the concentration in dry weight (dw) of several metal(oid)s (As, Cd, Cr, Cu, Mn, Ni, Pb, and Zn), as well as the abundance and characteristics of microplastics (MP) in wet weight (ww) of the soft tissues of clam Corbicula fluminea from Chubut River (Patagonia, Argentina). The contents of essential elements were in the following decreasing order: Zn > Mn > Cu > Ni; meanwhile, non-essential elements Cd, Cr and Pb were below the detection limit (<0.5 μg/g dw). A high mean concentration of As (6.1 ± 0.3 μg/g dw) was found, surpassing the maximum allowable limit established by the Argentine Food Code for bivalve molluscs. The number of MP ranged from 0.07 to 1.27 items/ind. and from 0.2 to 2.9 items/g ww. Fibers were the most common shape, mainly transparent. The size of MP ranged from 42 to 1917 μm, accounting for 62 % of MP between 50 and 450 μm. The dominant polymer was PET based on the results of Raman spectroscopy. Based on the widespread distribution of MP in the environment and the wide range of effects on organisms, it is necessary to develop long-term monitoring programs for MP contamination in different environmental matrices. Understanding the bioaccumulation of MP in bivalves is crucial to assess the potential risk to human health through consumption and to the ecosystem. We propose that the widespread Asian clam could serve as a useful biomonitor for MP and As pollution in freshwater and estuarine environments such as the Chubut River.

URBANIZATION IN INDIA: AN EVALUATION FROM ENVIRONMENTAL PERSPECTIVES

Urbanization is a process taking place globally intertwined with economic development. Urbanization is a process that leads to the growth of cities due to industrialization and economic development, and that leads to urban- specific changes in specialization, labor division and human behaviors. Urbanization refers to general increase in population and the amount of industrialization of a settlement. The population is growing at the rate of about 17 million annually which means a staggering 45,000 births per day and 31 births per minutes. If the current trend continues, by the year 2050, India would have 1620 million populations. It includes increase in the number and extent of cities. It symbolizes the movement of people from rural to urban areas. Urbanization happens because of the increase in the extent and density of urban areas. The most emerging issues are climate changes, freshwater scarcity, deforestation, and fresh water pollution and population growth. Although it is impossible to restrict urbanization it has to be ensured that urbanization proceeds in the right path causing minimum impact on environment. KEYWORDS: Urbanization, Environmental, Growth, scarcity, deforestation

Health Effects of Heavy Metal Contamination in Drinking Water

Water is essential for life, be it the life of animals, plants or human beings. It’s our prime duty to protect, manage and preserve the quality of water. Uncontrolled anthropogenic activities have resulted in contamination of fresh water resources thereby affecting the health of living beings. Rampant industrialization is a major environmental problem on the global scale for the pollution of fresh water with toxic effluents containing heavy metals. Contamination of surface water by heavy metals is the greatest quality issues because of their toxic nature, increased release and negative impact on the health of human beings. Water-borne diseases remain one of the major health concerns in the world. Heavy metals are individual metals and metal compounds that can impact human health. Exposure of humans to metals such as antimony, arsenic, barium, cadmium, chromium, cobalt, copper, iron, lead, manganese, mercury, nickel, selenium, silver, tin, zinc, etc results in chronic and acute toxicities. The toxicity of heavy metals depends on their concentration, period of exposure and route of exposure. Humans are exposed to heavy metals either by inhalation from the atmosphere, intake through drinking water, or by ingestion through the skin by dermal contact. The present review describes the analysis of ‘heavy metal contamination in drinking water’ with reference to definition, sources, health effects on humans and preventive measures. This study suggests that, the best way to get rid of heavy metal contamination in drinking water is to remove toxic heavy metals by using the best water purification system. Also, the ground water resources must be monitored for quality assessment, source identification and bioremediation of heavy metals.

Aquatic life criteria of hydrothermal liquefaction wastewater via ecotoxicity test and modeling

Wastewater resulting from hydrothermal liquefaction (HTL-AP) of biowaste is gaining attention as an emerging hazardous material. However, there is a lack of specific and systematic ecotoxicity studies on HTL-AP. This study addresses this gap by conducting acute toxicity tests on HTL-AP using typical aquatic species and integrating these results with predicted toxicity values from interspecies correlation estimation models to establish aquatic life criteria. HTL-AP exhibited significant toxicity with LC50 of 956.12–3645.4 mg/L, but demonstrated moderate toxicity compared to common freshwater pollutants like commercial microbicides, personal care products, and insect repellents. The resulting hazardous concentration for 5 % of species (HC5), the criterion maximum concentration, and the short-term water quality criteria for aquatic were 506.0, 253.0, and 168.7 mg/L, respectively. Notably, certain organisms like Misgurnus anguillicaudatus and Cipangopaludina chinensis showed high tolerance to HTL-AP, likely due to their metabolic capabilities on HTL-AP components. The significant decrease in HC5 values for some HTL-AP substances compared to pure compounds could indicate the synergistic inhibition effects among HTL-AP compositions. Furthermore, according to the established criteria, HTL-AP required significantly less diluted water (13 t) than carbendazim (1009 t) to achieve biosafety, indicating a safer release. This research establishes a preliminary water quality criterion for HTL-AP, offering a valuable reference for risk assessment and prediction in the utilization of HTL-AP within environmental contexts.

Improving photocatalytic efficiency: Harnessing the importance of Ag@HfO2 core-shell nanostructures

Pollution of fresh water has resulted from waste generated by agricultural and industrial activities. The pollutants need to be removed from water owing to the growing demand for drinking water due to an increase in the population. Hence, the effective treatment of synthetic dyes and their release into the environment is crucial. In this study, Ag@HfO2 core-shell nanostructures were synthesized and presented as a new catalyst for removing cationic dyes - such as rhodamine B (RhB), methylene blue (MB), and direct red-23 (DR-23) - from wastewater. X-ray diffractometry (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–Vis, and photoluminescence (PL) spectroscopies were employed to verify the synthesis success of Ag@HfO2 core-shell nanostructures in this study. The Ag@HfO2 core-shell nanostructures' effectiveness for photodegradation were tested by removing dyes associated with photo-catalytic measurements with high efficiency in both the UV and visible regions. The results are expected to contribute towards solving an environmental health issue deemed critical.