Chemodiversity in freshwater health.

Dissolved organic matter may offer a way to track and restore the health of fresh waters.

Synthetic musks in the natural environment: Sources, occurrence, concentration, and fate-A review of recent developments (2010-2023).

Synthetic musks (SMs) have served as cost-effective substitutes for natural musk compounds in personal care and daily chemical products for decades. Their widespread use has led to their detection in various environmental matrices, raising concerns about potential risks. Despite numerous studies on SM levels in different natural environments, a systematic review of their contemporary presence is lacking. This review aims to address this gap by summarising recent research developments on SMs in diverse natural environments, including river water, lake water, seawater, estuarine water, groundwater, snow, meltwater, sediments, aquatic suspended matter, soils, sands, outdoor air, and atmospheric particulate matter. Covering the period from 2010 to 2023, the review focuses on four SM categories: nitro, polycyclic, macrocyclic, and alicyclic. It systematically examines their sources, occurrences, concentrations, spatial and temporal variations, and fate. The literature reveals widespread detection of SMs in the natural environment (freshwater and sediments in particular), with polycyclic musks being the most studied group. Both direct (e.g., wastewater discharges) and indirect (e.g., human recreational activities) sources contribute to SM presence. Levels of SMs vary greatly among studies with higher levels observed in certain regions, such as sediments in Southeast Asia. Spatial and temporal variations are also evident. The fate of SMs in the environment depends on their physicochemical properties and environmental processes, including bioaccumulation, biodegradation, photodegradation, adsorption, phase exchange, hydro-dilution effects. Biodegradation and photodegradation can decrease SM levels, but may produce more persistent and eco-toxic products. Modelling approaches have been employed to analyse SM fate, especially for indirect processes like photodegradation or long-distance atmospheric transport. Future studies should further investigate the complex fate if SMs and their environmental influence. This review enhances understanding of SM status in the natural environment and supports efforts to control environmental contamination.

Analysis and modelling of profiles to understand fractionation processes for contaminations with polychlorinated biphenyls observed in fish.

Polychlorinated biphenyls (PCB) both continue to spread into the environment and to bioaccumulate from primary urban and industrial sources as well as from secondary sources such as soils and the oceans. Fractions of congeners in PCB mixtures, i.e. PCB profiles, can be used as fingerprints to trace contamination pathways from sources to sinks because PCB mixtures fractionate during transport due to congener specific phase changes and degradation. Using a statistical analysis of a total of 8584 PCB profiles with seven congeners (CB28, CB52, CB101, CB118, CB138, CB153, CB180) for contaminated fish from two international datasets as well as a modelling of profiles, two major fractionation processes related to distinct contamination pathways were identified: (1) A relative enrichment of lighter congeners (CB28, CB52, CB101) in seawater fish due to a predominantly atmospheric transport, whereas freshwater and some coastal fish had higher fractions of heavier congeners (CB138, CB153) because those were mainly contaminated by particle-sorbed PCB from surface runoff. (2) A temperature driven fractionation tended to affect congeners with a medium molecular weight (CB118) as well as the heaviest congeners (CB180), a fractionation process which was conceptually associated with transport of PCB from secondary sources. Specifically, medium chlorinated PCB is sufficiently volatile and persistent for a preferred transport into cooler waters. In warmer climates, only the highest chlorinated congeners are persistent enough to ultimately accumulate in fish. Our analysis and modelling provide a starting point for the development of systems to trace - better than before - sources of PCB contaminations observed in fish.

Non-traditional abiotic drivers explain variability of chlorophyll-a in a shallow estuarine embayment.

Understanding the factors influencing eutrophication, as represented by concentrations of chlorophyll-a (Chl-a), is needed to inform effective management and conservation strategies promoting ecological resilience. The objective of this study was to evaluate a unique combination of abiotic explanatory factors to describe Chl-a concentrations within the study estuary (North Biscayne Bay, Florida, USA). Multiple linear regression determined the strength and direction of influence of factors using data from 10 water quality monitoring stations. The analysis also considered time scales for evaluating cumulative effects of freshwater inflow and wind. Results show that dominant drivers of Chl-a were temperature, freshwater volume (whose cumulative effects were evaluated up to a 60-day time scale), and turbidity, which were statistically significant at 60, 60, and 70 % of the investigated stations, respectively. All drivers collectively accounted for 22 to 63 % of the variability of Chl-a measurements. Of the nine variables evaluated, nutrient concentrations (orthophosphate and ammonia) were not among the top three overall drivers. Despite nutrients historically being cited in the literature as the most significant factor, this study asserts that non-nutrient factors often govern Chl-a levels, necessitating a paradigm shift in management strategies to bolster estuarine resilience against climate change.

What, How, When, and Where: Spatiotemporal Water Quality Hazards of Cyanotoxins in Subtropical Eutrophic Reservoirs.

Though toxins produced during harmful blooms of cyanobacteria present diverse risks to public health and the environment, surface water quality surveillance of cyanobacterial toxins is inconsistent, spatiotemporally limited, and routinely relies on ELISA kits to estimate total microcystins (MCs) in surface waters. Here, we employed liquid chromatography tandem mass spectrometry to examine common cyanotoxins, including five microcystins, three anatoxins, nodularin, cylindrospermopsin, and saxitoxin in 20 subtropical reservoirs spatially distributed across a pronounced annual rainfall gradient. Probabilistic environmental hazard analyses identified whether water quality values for cyanotoxins were exceeded and if these exceedances varied spatiotemporally. MC-LR was the most common congener detected, but it was not consistently observed with other toxins, including MC-YR, which was detected at the highest concentrations during spring with many observations above the California human recreation guideline (800 ng/L). Cylindrospermopsin was also quantitated in 40% of eutrophic reservoirs; these detections did not exceed a US Environmental Protection Agency swimming/advisory level (15,000 ng/L). Our observations have implications for routine water quality monitoring practices, which traditionally use ELISA kits to estimate MC levels and often limit collection of surface samples during summer months near reservoir impoundments, and further indicate that spatiotemporal surveillance efforts are necessary to understand cyanotoxins risks when harmful cyanobacteria blooms occur throughout the year.

Physiological responses and removal mechanisms of ciprofloxacin in freshwater microalgae.

Antibiotics, such as ciprofloxacin (CIP), are frequently detected in various environmental compartments, posing significant risks to ecosystems and human health. In this study, the physiological responses and elimination mechanisms of CIP in Chlorella sorokiniana and Scenedesmus dimorphus were determined. The exposure CIP had a minimal impact on the growth of microalgae, with maximum inhibit efficiency (IR) of 5.14% and 22.74 for C. sorokiniana and S. dimorphus, respectively. Notably, the photorespiration in S. dimorphus were enhanced. Both microalgae exhibited efficient CIP removal, predominantly through bioaccumulation and biodegradation processes. Intermediates involved in photolysis and biodegradation were analyzed through Liquid Chromatography High Resolution Mass Spectrometer (HPLC-MS/MS), providing insights into degradation pathways of CIP. Upregulation of key enzymes, such as dioxygenase, oxygenase and cytochrome P450, indicated their involvement in the biodegradation of CIP. These findings enhance our understanding of the physiological responses, removal mechanisms, and pathways of CIP in microalgae, facilitating the advancement of microalgae-based wastewater treatment approaches, particularly in antibiotic-contaminated environments.

Fate, behaviour and microbial response of diluted bitumen and conventional crude spills in a simulated warm freshwater environment.

Diluted bitumen (DB), one of the most transported unconventional crude oils in Canada's pipelines, raises public concerns due to its potential spillage into freshwater environments. This study aimed to compare the fate and behaviour of DB versus conventional crude (CC) in a simulated warm freshwater environment. An equivalent of 10 L of either DB or CC was spilled into 1200 L of North Saskatchewan River (NSR) water containing natural NSR sediment (2.4 kg) in a mesoscale spill tank and its fate and behaviour at air/water temperatures of 18 °C/24 °C were monitored for 56 days. Oil mass distribution analysis showed that 42.3 wt % of CC and 63.6 wt% of DB resided in the oil slicks at the end of 56-day tests, consisting mainly high molecular weight (HMW) compounds (i.e., resins and asphaltenes). The lost oil contained mainly low molecular weight (LMW) compounds (i.e., light saturates and some aromatics) into the atmosphere, water column, and sediment through collective weathering processes. Notably, weathered CC emulsified with water and remained floating until the end, while the weathered DB mat started to lose its buoyancy after 24 days under quiescent conditions and resurfaced once waves were applied. Analysis of the microbial communities of water pre- and post-spills revealed the replacement of indigenous microbial communities with hydrocarbon-degrading species. Exposure to CC reduced the microbial diversity by 12%, while exposure to DB increased the diversity by 10%. During the early stages of the spill (up to Day 21), most dominant species were positively correlated with the benzene, toluene, ethylbenzene, and xylenes (BTEX) content or polycyclic aromatic hydrocarbon (PAH) content of the water column, while the dominant species at the later stages (Days 21-56) of the spill were negatively correlated with BTEX or PAH content and positively correlated with the total organic carbon (TOC) content in waters.

Analysis of environmental biological effects and OBT accumulation potential of microalgae in freshwater systems exposed to tritium pollution.

The ecological risk of tritiated wastewater into the environment has attracted much attention. Assessing the ecological risk of tritium-containing pollution is crucial by studying low-activity tritium exposure's environmental and biological effects on freshwater micro-environment and the enrichment potential of organically bound tritium (OBT) in microalgae and aquatic plants. The impact of tritium-contaminated wastewater on the microenvironment of freshwater systems was analyzed using microcosm experiments to simulate tritium pollution in freshwater systems. Low activity tritium pollution (105 Bq/L) induced differences in microbial abundance, with Proteobacteria, Bacteroidota, and Desulfobacterota occupying important ecological niches in the water system. Low activity tritium (105-107 Bq/L) did not affect the growth of microalgae and aquatic plants, but OBT was significantly enriched in microalgae and two aquatic plants (Pistia stratiotes, Spirodela polyrrhiza), with the enrichment coefficients of 2.08-3.39 and 1.71-2.13, respectively. At the transcriptional level, low-activity tritium (105 Bq/L) has the risk of interfering with gene expression in aquatic plants. Four dominant cyanobacterial strains (Leptolyngbya sp., Synechococcus elongatus, Nostoc sp., and Anabaena sp.) were isolated and demonstrated good environmental adaptability to tritium pollution. Environmental factors can modify the tritium accumulation potential in cyanobacteria and microalgae, theoretically enhancing food chain transfer.

Assessing ecological responses to exposure to the antibiotic sulfamethoxazole in freshwater mesocosms.

Antibiotics are a contaminant class of worldwide concern as they are frequently detected in aquatic ecosystems. To better understand the impacts of antibiotics on aquatic ecosystems, we conducted an outdoor mesocosm experiment in which aquatic communities were exposed to different concentrations of the antibiotic sulfamethoxazole (0, 0.15, 1.5, 15 and 150 µg/L). These concentrations include mean (0.15 µg/L) and maximum detected concentrations (15 and 150 µg/L) in aquatic ecosystems worldwide. Sulfamethoxazole was applied once a week for eight consecutive weeks to 1530 L outdoor mesocosms in the Netherlands, followed by an eight-week recovery period. We evaluated phytoplankton-, bacterial- and invertebrate responses during and after sulfamethoxazole exposure and assessed impacts on organic matter decomposition. Contrary to our expectations, consistent treatment-related effects on algal and bacterial communities could not be demonstrated. In addition, sulfamethoxazole did not significantly affect zooplankton and macroinvertebrate communities. However, some effects on specific taxa were observed, with an increase in Mesostoma flatworm abundance (NOEC of <0.15 µg/L). In addition, eDNA analyses indicated negative impacts on the insects Odonata at a sulfamethoxazole concentration of 15 µg/L. Overall, environmentally relevant sulfamethoxazole concentration did not result in direct or indirect impairment of entire aquatic communities and ecological processes in our mesocosms. However, several specific macroinvertebrate taxa demonstrated significant (in)direct effects from sulfamethoxazole. Comparison of the results with the literature showed inconsistent results between studies using comparable, environmentally relevant, concentrations. Therefore, our study highlights the importance of testing the ecological impacts of pharmaceuticals (such as sulfamethoxazole) across multiple trophic levels spanning multiple aquatic communities, to fully understand its potential ecological threats.

Behaviour of synthetic musk fragrances in freshwaters: occurrence, relations with environmental parameters, and preliminary risk assessment.

The aims of this study were to investigate the presence, possible sources, and potential ecological risks of synthetic musk fragrances in freshwaters and sediments of the main tributaries of a deep subalpine lake in Northern Italy. The total musk concentrations ranged from few ng L-1 up to values > 500 ng L-1, depending on river characteristics: water flow and the presence of wastewater effluents proved to be the main factors affecting fragrance concentrations. The water flow may indeed dilute fragrance input mainly deriving from treated wastewaters. Good correlations (determination coefficients > 0.60) between synthetic fragrances concentrations and parameters related to anthropogenic impacts confirmed this hypothesis: synthetic fragrances were mainly detected in most polluted rivers crossing urbanized areas. Sediment analysis highlighted accumulation of fragrances in this matrix. Concentrations of synthetic fragrances up to 329 ng g-1 organic carbon were measured in sediments of the most contaminated rivers Boesio and Bardello, which also show the highest nutrient content. The preliminary environmental risk assessment revealed that present levels of synthetic musk fragrances do not pose any risk to the studied environmental compartments. However, a probable medium risk level was evidenced during the dry season in the most contaminated rivers Boesio and Bardello. For these reasons, small rivers draining urbanized watersheds and affected by wastewater effluents should be considered synthetic musk contamination hotspots that warrant further research.

Bioaccumulation of polystyrene microplastics and changes in antioxidant and AChE pattern in a freshwater snail (Filopaludina bengalensis) from river Ganga.

Microplastic pollution is a leading global problem affecting terrestrial and marine aquatic ecosystems. Due to the stagnant nature of microplastics, the toxic effect of microplastics is more pronounced to benthic organisms than the surface feeder. Hence, the present study effort was to study the microplastic bioaccumulation pattern and changes in the enzymatic and nonenzymatic antioxidant and AChE pattern of freshwater snail Filopaludina bengalensis, which were subjected to 0.5 ppm to 5 ppm levels of polystyrene microsphere (∼ 30 µm) for 27 days. The study showed that microplastics were easily accumulated in the test organism in a dose and time-dependent manner, amounting to 82 ± 6.02 particles /individuals at a 5 ppm dose on the 27th day. However, no mortality was observed at the test microplastic dosages. The enzymatic antioxidant profile (SOD and catalase) showed limited variability and remained stable with increased duration and microplastic dose. However, the nonenzymatic antioxidant profile showed distinct variability with the complete seizing of the DPPH activity on the 27th day at 5 ppm microplastic dose and a gradual decrease of ABTS and FRAP activity at all the dose ranges. Even the AChE activity decreased with higher exposure concentrations. The present study for the first time shows the direct impact of microplastics on a freshwater snail widely available in the Indian subcontinent, indicating the role of microplastic pollution will create havoc in the Ganga river eco-biosystem in the long run.

Future emergence of new ecosystems caused by glacial retreat.

Glacier shrinkage and the development of post-glacial ecosystems related to anthropogenic climate change are some of the fastest ongoing ecosystem shifts, with marked ecological and societal cascading consequences1-6. Yet, no complete spatial analysis exists, to our knowledge, to quantify or anticipate this important changeover7,8. Here we show that by 2100, the decline of all glaciers outside the Antarctic and Greenland ice sheets may produce new terrestrial, marine and freshwater ecosystems over an area ranging from the size of Nepal (149,000 ± 55,000 km2) to that of Finland (339,000 ± 99,000 km2). Our analysis shows that the loss of glacier area will range from 22 ± 8% to 51 ± 15%, depending on the climate scenario. In deglaciated areas, the emerging ecosystems will be characterized by extreme to mild ecological conditions, offering refuge for cold-adapted species or favouring primary productivity and generalist species. Exploring the future of glacierized areas highlights the importance of glaciers and emerging post-glacial ecosystems in the face of climate change, biodiversity loss and freshwater scarcity. We find that less than half of glacial areas are located in protected areas. Echoing the recent United Nations resolution declaring 2025 as the International Year of Glaciers' Preservation9 and the Global Biodiversity Framework10, we emphasize the need to urgently and simultaneously enhance climate-change mitigation and the in situ protection of these ecosystems to secure their existence, functioning and values.

Nowhere to go! Microplastic abundances in freshwater fishes living near wastewater plants.

Microplastic presence in aquatic environments is a major problem globally. This study quantified microplastic abundances in fish species across two systems in South Africa around wastewater treatment works. Fish (n = 163) were examined for microplastic in gills and gastrointestinal tracts. Microplastic levels were generally low during the cool-dry season (mean 11.0 - 34.0 particles per fish taxon), and high during the hot-wet season (mean 10.0 - 119.0 particles per fish taxon). The microplastic concentrations per fish were similar between these systems, with downstream of wastewater treatment plants having high microplastic abundances. Although benthopelagic feeders were dominant, pelagic feeders had high microplastic abundances (range 20-119 particles), followed by benthopelagic (range 10-110 particles) and demersal (22 particles) feeders. Multiple regression analysis revealed a significant positive relationship between fish standard length and total microplastic levels, which suggests fish consume more microplastics due to increased food demand as a result of growth.

Antimicrobial resistance in southeast Asian water environments: A systematic review of current evidence and future research directions.

Antimicrobial resistance has been a serious and complex issue for over a decade. Although research on antimicrobial resistance (AMR) has mainly focused on clinical and animal samples as essential for treatment, the AMR situation in aquatic environments may vary and have complicated patterns according to geographical area. Therefore, this study aimed to examine recent literature on the current situation and identify gaps in the AMR research on freshwater, seawater, and wastewater in Southeast Asia. The PubMed, Scopus, and ScienceDirect databases were searched for relevant publications published from January 2013 to June 2023 that focused on antimicrobial resistance bacteria (ARB) and antimicrobial resistance genes (ARGs) among water sources. Based on the inclusion criteria, the final screening included 41 studies, with acceptable agreement assessed using Cohen's inter-examiner kappa equal to 0.866. This review found that 23 out of 41 included studies investigated ARGs and ARB reservoirs in freshwater rather than in seawater and wastewater, and it frequently found that Escherichia coli was a predominant indicator in AMR detection conducted by both phenotypic and genotypic methods. Different ARGs, such as blaTEM, sul1, and tetA genes, were found to be at a high prevalence in wastewater, freshwater, and seawater. Existing evidence highlights the importance of wastewater management and constant water monitoring in preventing AMR dissemination and strengthening effective mitigation strategies. This review may be beneficial for updating current evidence and providing a framework for spreading ARB and ARGs, particularly region-specific water sources. Future AMR research should include samples from various water systems, such as drinking water or seawater, to generate contextually appropriate results. Robust evidence regarding standard detection methods is required for prospective-era work to raise practical policies and alerts for developing microbial source tracking and identifying sources of contamination-specific indicators in aquatic environment markers.

Nutritional values of wild edible freshwater macrophytes.

Background: The social acceptability of wild freshwater macrophytes as locally consumed vegetables is widespread. Freshwater macrophytes have several uses; for example, they can be used as food for humans. This study determined the proximate composition and mineral content of three freshwater macrophyte species, i.e., Eichhornia crassipes, Limnocharis flava, and Neptunia oleracea. Methods: Young shoots of E. crassipes, L. flava, and N. oleracea were collected from shallow channels of Puchong (3°00'11.89″N, 101°42'43.12″E), Ladang 10, Universiti Putra Malaysia (2°58'44.41″N, 101°42'44.45″E), and Kampung Alur Selibong, Langgar (06°5'50.9″N, 100°26'49.8″E), Kedah, Peninsular Malaysia. The nutritional values of these macrophytes were analysed by using a standard protocol from the Association of Official Analytical Chemists. Eight replicates of E. crassipes and L. flava and four replicates of N. oleracea were used for the subsequent analyses. Results: In the proximate analysis, N. oleracea possessed the highest percentage of crude protein (29.61%) and energy content (4,269.65 cal g-1), whereas L. flava had the highest percentage of crude fat (5.75%) and ash (18.31%). The proximate composition trend for each species was different; specifically, all of the species possessed more carbohydrates and fewer crude lipids. All of the species demonstrated a similar mineral trend, with high nitrogen and potassium and lower copper contents. Nitrogen and potassium levels ranged from 12,380-40,380 mg kg-1 and from 11,212-33,276 mg kg-1, respectively, and copper levels ranged from 16-27 mg kg-1. The results showed that all three plant species, i.e., E. crassipes, N. oleracea, and L. flava are plant-based sources of macro- and micronutrient beneficial supplements for human consumption.

Assessment of microplastic contamination in the Loire River (France) throughout analysis of different biotic and abiotic freshwater matrices.

The contamination of microplastics (MP) in freshwater environments represent a major way for the MP transport in the environment. The assessment of MP pollution in freshwater compartments is then important to visualize the pressure and the impacts on medium, and to set up necessary measures. In this context, this study focused on the influence of anthropogenic activities of a medium French city (Angers) on MP levels in samples collected from the Loire River, the longest river in France. Abiotic and biotic matrices were collected upstream and downstream Angers. A first analysis was performed based on microscopy to determine the size, colour and shape of suspected MP and a complementary analysis by µ-FTIR (micro-Fourier Transform InfraRed) was conducted to determine the composition of plastic particles. Three organisms belonging to different trophic levels were studied: when the MP level was expressed per individual, the lowest abundance of MP was found in Tubifex sp. Followed by Corbicula fluminea, while the highest was measured in Anguilla anguilla. To establish the relationship with their habitat, the presence of MP in sediment and water was also analysed. Therefore, this works constitutes a complete overview of the MP levels in freshwater abiotic and biotic matrices. Overall, the presence of MP in analysed samples did not follow a particular pattern, neither in the sites nor matrices: the characteristics depending on a multifactorial outcome (feeding mode, organism size …). However, correlation of MP pattern between clams and sediment was quite evident, while the one between worms and their habitat was not. This demonstrates the relevance of investigating plastic contamination both in biotic and abiotic matrices. Finally, a standardisation of sampling and analytical analysis protocols would be helpful to make comparisons between studies more robust.

Untreated wastewater impact and environmental risk assessment of artificial sweeteners in river water and sediments of the Danube River Basin in Serbia.

Artificial sweeteners are receiving increasing attention as newly recognized emerging contaminants that mainly reach the aquatic environment through the discharge of municipal wastewater containing large amount of these compounds. In this study, the impact of raw untreated wastewater discharges on the levels and the water/sediment distribution of artificial sweeteners in the Danube River and its largest tributaries in Serbia was evaluated, and a comprehensive assessment of environmental risks for freshwater and benthic organisms was performed. Acesulfame and sucralose were detected in all river water samples (100%), while saccharin (59%) and cyclamate (12%) were less frequently found, indicating long-term continuous sewage-derived pollution. Aspartame (100%) and neotame (60%) were the only artificial sweeteners recorded in the sediment samples due to their preference to sorb to particulate matter in the water/sediment system. In terms of ecotoxicological risk, a low risk for aquatic organisms was determined at the detected levels of saccharin in river water, while a high to medium risk was found for benthic biota at the concentrations of neotame and aspartame detected in sediments. The largest contribution to the pollution of the Danube River Basin with artificial sweeteners, and consequently the highest environmental risk, was determined in the two largest cities, the capital Belgrade and Novi Sad, which raises the issue of transboundary pollution.

Abundance and characteristics of microplastics in a freshwater river in northwestern Himalayas, India - Scenario of riverbank solid waste disposal sites.

Microplastics (MPs) are one of the challenging and established contaminants that have adverse implications on human health. The focus of this study was to quantify and analyze the contribution of unscientific municipal solid waste (MSW) disposal sites to the MPs in the Jhelum River and the risk associated with it. Quantitative analysis of our study showed a mean MP concentration of 1474 ± 1026 particles/m3 for the entire stretch of the river. All the sites confirmed the presence of MPs with the concentration ranging from 600 particles/m3 to 2500 particles/m3. The size distribution of MPs suggested that 34 % of the microplastics ranged between 300 µm to 75 µm while 66 % of the particles varied between 300 µm to 5 mm. The concentrations of MPs downstream of unscientific disposal sites were found to increase threefold to that of upstream. The Fourier Transform Infrared Spectroscopy (FT-IR) confirmed the presence of polyethylene (PE) in the majority followed by polyvinyl chloride (PVC) and polypropylene (PP). The flakes were dominant throughout the river followed by filaments, fragments, and spherules. Count based Pollution level indexing (PLI) estimated 3-14 times MP contamination in the river with respect to contamination in glacial runoffs. The risk assessment study of the MPs indicated an increase of around 10.2 % in ingestion rates of MPs due to the unscientific disposal of MSW on the banks of the freshwater body. The values of polymer hazard index (PHI) and potential ecological risk index (PERI) were in the extreme case of pollution (PHI>1000 and PERI>1200). This study manifests the adversities of unscientific municipal solid waste disposal for timely waste management.

Metal pollution in freshwater fish: A key indicator of contamination and carcinogenic risk to public health.

Metals are micropollutants that cannot be degraded by microorganisms and are infiltrated into various environmental media, including both freshwater and marine water. Metals from polluted water are absorbed by many aquatic species, especially fish. Fish is a staple food in the diets of many regions in the world; hence, both the type and concentration of metals accumulated and transferred from contaminated water sources to fish must be determined and assessed. In this study, the heavy metal concentration was determined and assessed in fish collected from freshwater sources via published literature and Estimated Daily Intake (EDI), Target hazard quotient (THQ), and Carcinogenic Risk (CR) analyses, aiming to examine the metal pollution in freshwater fish. The fish was used as a bioindicator, and Geographic information system (GIS) was sued to map the polluted regions. The results confirmed that Pb was detected in fish sampled at 28 locations, Cr at 24 locations, Cu and Zn at 30 locations, with values Pb detected ranging from 0.0016 mg kg-1 to 44.3 mg kg-1, Cr detected ranging from 0.07 mg kg-1 to 27 mg kg-1, Cu detected ranging from 0.031 mg kg-1 to 35.54 mg kg-1, and Zn detected ranging from 0.242 mg kg-1 to 103.2 mg kg-1. The strongest positive associations were discovered between Cu-Zn (r = 0.74, p < 0.05) and Cr-Zn (r = 0.57, p < 0.05). Spatial distribution maps depicting the consumption of fish as food and its corresponding Pb and Cr intake revealed a higher incidence of both carcinogenic and non-carcinogenic health concerns attributed to Pb and Cr in the region with populations consuming the fish.