Assessment of metal mobility in sediment, commercial fish accumulation and impact on human health risk in a large shallow plateau lake in southwest of China

Ecological and public health risk assessment of potentially toxic elements in the surface sediments of the Pasur river estuary, Bangladesh

Potentially toxic elements (PTEs) in the surface sediments of the Pasur river estuary was investigated to assess its distribution, potential sources, and current dangers to ecological and public health. The Pasur River is a tidal, meandering, perennial river in south-western Bangladesh with a considerable number of fisheries and industrial activities. Sediment samples were collected from seven sampling points from January to December 2022 to assess the contamination level of six potentially toxic elements (Pb, Cr, Cd, As, Cu and Zn). Flame Atomic Absorption Spectrophotometer was utilized to detect the concentration of PTEs by following some sequential analytical procedure. Concentration of PTEs followed the reducing trend of Zn > Cr > Pb > As > Cu > Cd with the mean value of 61.04 > 49.15 > 26.58 > 10.28 > 6.28 > 1.59 mg/kg, respectively. The principle component and cluster analyses justified the anthropogenic source of the studied PTEs. The mean values of contamination factor (CF), geo-accumulation index (Igeo) and enrichment factor (EFc) showed that Pb and Cd were highly responsible for sediment (uncontaminated to moderate) contamination. Pollution load index (PLI) indicated higher pollution of sediments near the port areas. Potential ecological risk index (PERI) indicated low to moderate risks due to the contaminated sediment. However, the contamination of sediment was not associated with the non-carcinogenic (HQderm and HI < 1) and carcinogenic (CRderm < 10-6) risks due to the dermal contact. Although the risks were within the tolerable limit, regular monitoring is suggested to reduce the risk of PTEs contamination.

Profound regional disparities shaping the ecological risk in surface waters: A case study on cadmium across China

The scientific advancement of water quality criteria (WQC) stands as one of the paramount challenges in ensuring the security of aquatic ecosystem. The region-dependent species distribution and water quality characteristics would impact the toxicity of pollutant, which would further affect the derivation of WQC across regions. Presently, however, numerous countries adhere to singular WQC values. The "One-size-fits-all" WQC value for a given pollutant may lead to either "over-protection" or "under-protection" of organisms in specific region. In this study, we used cadmium(Cd) pollution in surface waters of China as a case study to shed light on this issue. This study evaluated critical water quality parameters and species distribution characteristics to modify WQC for Cd across distinct regions, thus unveiling the geographical variations in ecological risk for Cd throughout China. Notably, regional disparities in ecological risk emerged a substantial correlation with water hardness, while species-related distinctions magnified these regional variations. After considering the aforementioned factors, the variation in long-term WQC among different areas reached 84-fold, while the divergence in risk quotient extended to 280-fold. This study delineated zones of both heightened and diminished ecological susceptibility of Cd, thereby establishing a foundation for regionally differentiated management strategies.

Metabarcoding of zooplankton communities of Dianchi Lake based on the mitochondrial cytochrome oxidase subunit 1 gene

Freshwater lakes as an essential component of the ecosystem, provide ecological resources in addition to economic source for humans. Under recent climate change scenario, preserving the biodiversity of freshwater ecosystems is crucial. This study aimed to characterize the diversity of zooplankton communities in Dianchi Lake, located in Kunming Municipality, Yunnan Province, China, using Illumina high-throughput sequencing of the cytochrome oxidase subunit 1 (COI) gene marker. A total of 18 water samples were collected including 16 from the outer sea area of Dianchi Lake: 4 from the east (E1-4), 4 from the west (W1-4), 4 from the south (S1-4), and 4 from the north (N1-4), and: 2 from the Caohai area (C1-2) as research sites. All environmental parameters including pH, ammonium (NH4+), total nitrogen (TN), total phosphorus (TP), chlorophyll a content (CHLA) were found to be insignificant (p > 0.05), except for chemical oxygen demand (COD) and transparency (T), which were found to be significant (p < 0.05). Alpha diversity indices including ACE, Chao1, Shannon, and Simpson showed non-significant differences (p > 0.05), indicating no variation in the richness of zooplankton communities at different locations of Dianchi Lake. However, principal coordinate analysis (PCoA) showed that most of the samples from East, West, and South groups were close to each other, showing more similarities among them, while Caohai and North group samples were distant from each other, showing more differences with other groups. Rotifera, Arthropoda, and Chordata were the top three phyla, while Keratella, Macrothrix, and Brachionus were the dominant genera. Mantel test analysis showed that COD and transparency were important environmental factors that shaped the Rotifera community structure of Dianchi Lake. In conclusion, this study provides insights on conserving the diversity of zooplankton communities in Dianchi Lake, especially by controlling COD and maintaining water transparency, in order to preserve its ecological resources and economic significance.

Considerations for environmental biogeochemistry and food security for aquaculture around Lake Victoria, Kenya

The impact of population expansion through economic growth and development has been identified as one of the key drivers of both water and sediment contamination from potentially harmful elements (PHEs). This presents a major hazard not only to aquatic ecosystems but local riparian communities and beyond who rely heavily on this natural resource for drinking water and fish-a valuable source of dietary micronutrients and protein. The present study measured biogeochemical concentration of PHEs in water, sediment and fish from locations pooled into four zones within Winam Gulf and Lake Victoria area of Kenya. Captured fish were used as a sentinel receptor of lake health to evaluate potential risks to fisheries and aquaculture food security. In water, concentrations of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu) and lead (Pb) were observed above the United States Environmental Protection Agency (US EPA) maximum contamination level drinking water guidelines (MCL), with aluminium (Al) observed above the Aquatic Life Criteria in all four zones. Similarly, sediment concentrations in all four zones exceeded the US EPA Effects range low (ERL) threshold guidelines for Cu, nickel (Ni), zinc (Zn) and Pb, with Cu, Zn and Pb classed at moderate contamination levels using the contamination factor. Fish tissue concentrations from the four zones were calculated using recommended daily intakes (RDI) and for PHEs as provisional maximum tolerable intakes (PMTIs) and indicated most macro- and micronutrients were at or below 10% RDI from aquaculture and wild fish, with Se indicating a greater RDI (16-29%) in all the zones. Contributions of PHEs to PMTIs were below threshold guidelines for both aquaculture and wild fish with only Cd, Cr and Pb levels being above the PMTI thresholds. There is a need to assess the long-term effects of persistent anthropogenic PHE input into Winam Gulf and the wider Lake Victoria basin. Continued monitoring of PHEs using both historical and more recent data will enable future management policies to be implemented through improved mitigation strategies to reduce their impact on water quality, fish health and subsequent human health.

Risk source identification and diffusion trends of metal(loid)s in stream sediments from an abandoned arsenic-containing mine

Stream sediments from mine area are a converging source of water and soil pollution. The risk and development trends of metal(loid)s pollution in sediments from an abandoned arsenic-containing mine were studied using modelling techniques. The results showed that the combined techniques of geographic information system (GIS), random forest (RF), and numerical simulation (NS) could identify risk sources and diffusion trends of metal(loid)s in mine sediments. The median values of As, Cd, Hg, and Sb in sediments were 5.01, 3.02, 5.67, and 3.20 times of the background values of stream sediments in China, respectively. As (14.09%) and Hg (18.64%) pollution in mine stream sediments were severe while As is the main potential risk source with a strong spatial correlation. High-risk blocks were concentrated in the landfill area, with the surrounding pollution shows a decreasing trend of "step-type" pollution. The risk correlation between Hg and As (55.37%) in the landfill area is high. As a case of arsenic, the diffusion capacity of As within 500m is strong and stabilizes at 1 km when driven by the flows of 0.05, 0.5, and 5 m³/s, respectively. With the worst-case scenario flow (86 m³/s), it would take only 147 days for the waters within 3 km to become highly polluted. The high pollution levels in a stream under forecast of different distance intervals (500, 1500, 2000 m) within 6.5 km is arrived at approximate 344, 357, and 384 days, respectively. The study suggested the combined technique of GIS, RF, and NS can serve the risk source identification of contaminated sites and risk forecast of toxic element diffusion in emergency situations.

Contamination of Selected Toxic Elements in Integrated Chicken-Fish Farm Settings of Bangladesh and Associated Human Health Risk Assessments

The presence of trace elements in the environment can contaminate a food chain of an agro farm in various ways. Integrated chicken-fish farms (i.e., where poultry chicken and fish are cultivated in same places) are getting popular nowadays to meet the demands of a balanced diet. The present study conducted a health risk assessment on the basis of selected heavy metal (i.e., Cr and Pb) and metalloid (i.e., As) contamination in this type of farm in Bangladesh. Samples of various types were collected from different farms between September 2019 and March 2020. The concentrations of the elements were checked by Flame-AAS and HG-AAS. Our findings demonstrated that the elements' concentrations in fishes were simultaneously induced by the habitation and bioaccumulation through the food chain of the farm. The concentrations of As and Pb in the chicken parts and Cr and As in some fishes were greater than the highest limits set by different permissible standards. Overall, the metal concentration obtained in different samples was in descending order: sediment > droppings > different fish parts > various species of chicken > pond water. Among the pollutants, As gave target hazard quotient (THQ) values higher than 1 for all the species, suggesting health risks from the intake of fishes and chicken. However, there was non-target cancer risk present while considering all the elements together. Notably, the study found carcinogenic risks of As, Pb, and Cr for humans due to poultry and/or fish consumption; the identified health risks associated with the integrated farming setting will be crucial in further tackling strategies. Investigation of the possible sources of heavy metals in commercial chicken feeds and regular monitoring of groundwater used for agro-farming are highly recommended to reduce the burden.

Metal-mining-induced sediment pollution presents a potential ecological risk and threat to human health across China: A meta-analysis

Aquatic sediment polluted by potentially toxic elements (PTEs) from mining activities represents a potential health "time bomb" for humans and the local ecology, but the integrated analysis of pollution and hazards of PTEs in sediment around typical metal mines in China is limited. Presently, the associated pollution status, spatial distribution, and ecological and health hazards of Cd, Cu, Zn, Pb, Cr, and As were investigated through index evaluation, spatial analysis, health risk assessment models, and Monte Carlo simulation. Overall, the sediment exhibited varying degrees of PTE contamination; notably, the level of Cd was 104.85 times higher than its background value, and it became the most enriched element in the surveyed sediment, followed in descending order by Cu, As, Zn, Pb, and Cr. Nationally, over 64.5% of metal-mining-affected sediment presented a very high ecological risk, contributed mostly by Cd (43.2%-98.7%) followed by As, Pb, and Cu; the risk contributed by both Cr and Zn was found to be negligible. The adverse health risk posed to children by most sediment was 1.72 and 6.46 times higher than that posed to adults for cancerous and noncancerous risks, respectively. The potential noncarcinogenic risks were mainly caused by As, which contributed over 78.9% of the Hazard Index values, then followed by Pb (>9.3%). For both children and adults, the carcinogenic risk of PTEs decreased in the following order: As > Cd > Cr > Pb. The investigated sediment was found seriously affected by nearby metal mines, especially those in regions with long-term and large-scale nonferrous-metal-mining activities. This study could provide a reference for policymakers to develop control strategies for PTE pollution in sediment around mining areas.

Assessment of heavy metal accumulation in Penaeus monodon and its human health implications

Asian tiger shrimp Penaeus monodon (P. monodon) of Chilika lagoon, India was studied regarding the metal accumulation and its associated human health risks. It showed a tendency of metal accumulation in the following order: Zn > Ni > Cu > Co > Cr > Pb > Cd. A two-way ANOVA indicated the metal accumulation was insignificant with respect to season (n = 421, p = 0.59) and sector (n = 32, p = 0.61). The estimated daily intake (EDI), targeted hazard quotient (THQ) and hazard index (HI), and carcinogenic risks (CR) revealed no potential human health risks and were safe for consumption. The pollution load index (PLI) of <1, Geo-accumulation index (Igeo,) and contamination factor (CF) indicated that the study area was unpolluted. This pioneering study highlighted that P. monodon was nurtured well in the healthy habitat of Chilika lagoon and the fair level of metal content made it an excellent source of dietary components.

Toxic Metals, Non-Metals and Metalloids in Bottom Sediments as a Geoecological Indicator of a Water Body's Suitability for Recreational Use

The study of bottom sediments was conducted within the basins of water bodies used for recreational purposes (e.g., bathing, fishing and diving) in the Silesian Upland and its periphery in southern Poland. Various concentrations of trace elements were found in bottom sediments, reflected by the following levels: Pb (30-3020 mg/kg), Zn (142-35,300 mg/kg), Cd (0.7-286 mg/kg), Ni (10-115 mg/kg), Cu (11-298 mg/kg), Co (3-40 mg/kg), Cr (22-203 mg/kg), As (8-178 mg/kg), Ba (263-19,300 mg/kg), Sb (0.9-52.5 mg/kg), Br (1-31 mg/kg), Sr (63-510 mg/kg) and S (0.001-4.590%). These trace elements are present in amounts that usually exceed those found in other bodies of water or are sometimes even unprecedented among bodies of water in the world (e.g., cadmium-286 mg/kg, zinc-35,300 mg/kg, lead-3020 mg/kg, arsenic-178 mg/kg). It was found that bottom sediments were contaminated to varying degrees with toxic metals, metalloids and non-metals, as evidenced by the values of geoecological indicators, i.e., the geoaccumulation index (-6.31 < I_geo < 10.90), the sediment contamination factor (0.0 ≤ Cfi < 286.0), the sediment contamination degree (4.6 < C_d < 513.1) and the ratios of the concentrations found to the regional geochemical background (0.5 < I_RE < 196.9). It was concluded that the presence of toxic elements (e.g., lead, zinc, cadmium, chromium, strontium and arsenic) in bottom sediments should be taken into account when classifying water bodies as suitable for recreational use. A maximum ratio of the concentrations found to the regional geochemical background of I_RE ≤ 5.0 was proposed as the threshold for the permissibility of recreational use of water bodies. The water bodies used for recreational purposes in the Silesian Upland and its periphery do not meet the geoecological conditions for safe use in terms of recreation and leisure activities. Forms of their recreational use that directly affect the participants' health (e.g., fishing and the consumption of fish and other aquatic organisms) should be abandoned.

Impacts of the Residual Trace Metals of Aquaculture in Net Cages on the Quality of Sediment

Anthropogenic pollution by trace metals in aquatic environments in semiarid zones is a critical area of investigation. The objective of this study was to investigate the concentration and spatial distribution of trace metals in surface sediments in the Rosário reservoir, which is affected by the intensive aquaculture of Tilápia-do-Nilo (Oreochromis niloticus). Sediment samples were collected in three different areas, postculture (PCTV), cultivation (CTV) and control (CTRL) in the dry season in 2019. The granulometric composition, organic matter and concentrations of Fe, Mn, Zn, Cu, Cr, Cd, Pb and Ni metals were determined. Multivariate statistics were used. Geochemical and ecotoxicological indices and a comparison with sediment quality guidelines (SQG) were used. The sediment was characterized by silty clay loam with an average organic matter of 18.76 ± 4.27. The analytical merit figures demonstrated accuracy (metal recoveries in certified standards) between 89 to 99% and high precision (RSD < 5%). The concentration ranges for the metals were Fe: 0.11-0.85 (%), Mn: 14.46-86.91, Zn: 2.6-220.56, Cu: 26.89-98.75, Cr: 60.18-76.06, Cd: 0.38-0.59, Pb: 18.13-43.13, and Ni: 34.4-46.75, all in (mg/kg^-1). The highest concentration values were found in the CTV areas (Fe: 40 ± 0.22, Mn: 66.48 ± 19.11, Zn: 114.83 ± 59.75 and Cr: 70.85 ± 2.62) and PCTV (Cd: 0.53 ± 0.04, Cu: 71.83 ± 21.20, Pb: 33.71 ± 4.34 and Ni: 44.60 ± 1.79). Pearson's correlation, hierarchical cluster analysis and principal component analysis confirmed the influence of fish farming on metals. Only Ni presented concentration values higher than the reference value established in the SQG. Thus, considering the probable geochemical and ecotoxicological effects, they comprise the two lowest levels of impact.

Potential human health risks associated with ingestion of heavy metals through fish consumption in the Gulf of Guinea

Heavy metal pollution of the marine environment has toxic implications for both the aquatic biota and human health. We examined the levels of Zinc (Zn), Lead (Pb), Copper (Cu), Cadmium (Cd), Arsenic (As) and Mercury (Hg) in muscles of Sardinella maderensis, Dentex angolensis, Sphyraena sphyraena and Penaeus notialis caught from the coastal waters of Ghana using inductively coupled plasma mass spectrometry method. Penaeus notialis recorded the highest concentrations of all the metals (Cu:12.08 ± 1.46 µg/g, Zn: 19.20 ± 2.27 µg/g, As: 8.46 ± 2.42 µg/g, and Cd: 0.03 ± 0.01 µg/g) except Hg. Mercury was relatively high in D. angolensis (0.14 ± 0.03 µg/g). Apart from As, all metals were within globally permissible daily limits for consumption by human per meal. The estimated Target Hazard Quotient due to the intake of Hg through D. angolensis consumption exceeded the threshold value across all age categories. Carcinogenic risks due to As intake through P. notialis consumption far exceeded the 10^-6 threshold for all age groups in Ghana. It is recommended that the consumption of these fish species particularly, the shrimp P. notialis be done cautiously to avoid possible future health challenges.

Trophodynamics and health risk assessment of toxic trace metals in the food web of a plateau freshwater lake

The trophodynamics of toxic trace metals is significant for assessing the threat of toxic trace metals to the aquatic ecosystem and human safety. However, due to the difficulty of accurately calculating the trophic positions of freshwater aquatic organisms in the food web, the comprehensive process of trophodynamics of toxic trace metals in freshwater ecosystems was still rarely known. By integrating the compound-specific nitrogen stable isotopic analysis of amino acids (CSIA-AAs) and the Bayesian stable isotope mixing model (SIMM) as a novel approach, the present study investigated the trophodynamics of five toxic trace metals (Zn, As, Cr, Cu, and Hg) in the food web of the YangZong Lake, a plateau freshwater lake that was once heavily polluted by arsenic in Yunnan Province, China. The results revealed that Hg tended to be efficiently biomagnified in the food web with a trophic magnification factor of 1.75; As, Cr, and Cu were biodiluted significantly, while Zn showed no biomagnification or biodilution trends. The dietary health risk assessment indicated the potential health risk of toxic trace metals for the local residents of long-term fish consumption. The present work highlights the accuracy and reliability of the novel CSIA-AAS+SIMM approach in the calculation of the trophic positions of freshwater organisms.

A human health risk assessment of methylmercury, arsenic and metals in a tropical river basin impacted by gold mining in the Colombian Pacific region

The Atrato River basin is one of the most biodiverse areas worldwide, and paradoxically, it is one of the sites in Colombia with the highest environmental impact from gold mining. This study assessed the distribution of Hg, As, Pb, and Cd in 47 fish species (n = 1372) and the accumulative human health risk in inhabitants (n = 2325) from 13 municipalities located along the Atrato River basin. The results revealed that Hg and As in fish present a high potential human health risk based on their mean concentrations. Estimated daily intake (EDI) calculations showed that humans could present detrimental health effects, while that target hazard quotient (THQ) above 1 showed that the exposed population might experience noncarcinogenic health risks, mainly from the accumulative effects of Hg (80.4%) and As (18.2%). The species that would most affect the health of the inhabitants are carnivorous H. malabaricus, A. pardalis, P. schultzi, R. quelen, and C. kraussii, which are among the fourteen most consumed in the region. These species had values of estimated weekly intake (EWI) above the provisional tolerable weekly intake thresholds for MeHg (PTWI of 1.6 and 3.2 μg/kg bw/week for adults and children, respectively) in 7 of the 13 localities evaluated. According to the surveys, the calculated weekly allowable fish amount (MFW) showed that carnivorous fish may generate adverse effects on the consumers because the allowed MeHg is about 2 times higher than the upper reference limit. Other results indicate a significant carcinogenic health risk, mainly from As, in 8 of the 13 localities evaluated. Due to the high rates of unsatisfied basic needs and the monetary poverty in the region, the possibility that inhabitants can replace fish as the principal source of protein is low. Therefore, a food guidance is required to avoid risks, obtain nutritional benefits, and sustain fish populations.

Contamination level, source identification and health risk assessment of potentially toxic elements in drinking water sources of mining and non-mining areas of Khyber Pakhtunkhwa, Pakistan

Accelerated mining activities have increased water contamination with potentially toxic elements (PTEs) and their associated human health risk in developing countries. The current study investigated the distribution of PTEs, their potential sources and health risk assessment in both ground and surface water sources in mining and non-mining areas of Khyber Pakhtunkhwa, Pakistan. Water samples (n = 150) were taken from selected sites and were analyzed for six PTEs (Ni, Cr, Zn, Cu, Pb and Mn). Among PTEs, Cr showed a high mean concentration (497) μg L^-1, followed by Zn (414) μg L^-1 in the mining area, while Zn showed the lowest mean value (4.44) μg L^-1 in non-mining areas. Elevated concentrations of Ni, Cr and a moderate level of Pb in ground and surface water of Mohmand District exceeded the permissible limits set by WHO. Multivariate statistical analyses showed that the pollution sources of PTEs were mainly from mafic-ultramafic rocks, acid mine drainage, open dumping of mine wastes and mine tailings. The hazard quotient (HQ) was the highest for children relative to that for adults, but not higher than the USEPA limits. The hazard index (HI) for ingestions of all selected PTEs was lower than the threshold value (HI_ing < 1), except for Mohmand District, which showed a value of HI >1 in mining areas through ingestion. Moreover, the carcinogenic risk (CR) values exceeded the threshold limits for Ni and Cr set by the USEPA (1.0E-04-1.0E-06). In order to protect the drinking water sources of the study areas from further contamination, management techniques and policy for mining operations need to be implemented.

Impact of nickel mining in New Caledonia on marbled eels Anguilla marmorata

New Caledonia is particularly affected by nickel open pit mining activities because of the presence of ultramafic soils rich in metals. The particles dispersed by atmospheric transport and soil erosion during the excavation of nickel end up by deposition or leaching in rivers where they may be bioaccumulated by organisms living downstream the mines. Despite alarming freshwater metals concentrations, no study investigated the level of their bioaccumulation in eels, and if high bioaccumulation levels occur, the potential consequences on their health. The aim of this study was to determine how eels Anguilla marmorata are impacted in situ by metals issued from mining activity by measuring: morphometric parameters; metal concentrations in tissues and organs and transcription levels of target genes encoding proteins involved in several metabolic key functions. Among organs, liver was found to be the most affected by mining with average nickel concentrations of 5.14 mg/kg versus 1.63 mg/kg for eels away from mines leading to dysregulation of numerous genes involved in oxidative stress, DNA repair, apoptosis, reproduction and both lipid and mitochondrial metabolisms. This study should allow us to define in an integrated way if metals released by mining activities influence metals bioaccumulation in eels and induce biological effects.

Distribution and Bioaccumulation of Essential and Toxic Metals in Tissues of Thaila (Catla catla) from a Natural Lake, Pakistan and Its Possible Health Impact on Consumers

Although fish are often recommended as a component of a healthy diet, the environmental accumulation of heavy metals in many fish species has been of considerable concern for those weighing the nutritional health benefits against adverse toxic outcome of excess intake of toxic metals. This study aimed to determine the concentration of essential and toxic metals in the tissues of Catla catla in Mangla Lake and to assess the possible risk to the consumers. Fifty samples of Catla catla were collected from Mangla Lake, Mirpur, Azad Jammu and Kashmir, Pakistan and analyzed for eighteen metals including essential and trace metals. The measured range concentrations (µg/g, wet weight) in muscle tissues, in decreasing order, were: K (955–1632), Ca (550–2081), Na (449–896), Mg (129–312), Zn (61.2–215), Fe (11.6–26.8), Sr (2.60–9.27), Pb (1.72–7.81), Se (1.55–3.55), Co (0.12–4.08), Mn (1.04–4.33), Ni (0.69–3.06), Cu (0.88–2.78), Cr (0.45–1.88), As (0.67–1.58), Cd (0.28–0.56), Hg (0.17–0.57) and Li (0.12–0.38). The metal concentrations found in this study were comparatively higher than those reported in literature. A majority of the metals exhibited higher accumulation in gills compared with those in scales and muscles. Mean levels of Pb, As, Co, Mn, Cd, Cr and Zn in Catla catla muscle were found to be exceeding the international permissible limits for the safe human consumption. The condition factor (K), as an indicator of fish health status, indicated that Catla catla of Mangla Lake are in good health condition. The metal pollution index (MPI) of gills (27.9), scales (12.5) and muscle (7.57) indicated low contamination. Moreover, human health risk was evaluated using estimated weekly intake (EWI) and daily intake (EDI), target hazard quotient (THQ), hazard index (HI) and target cancer risk (TCR). Estimated weekly and daily intake values for As, Cd, Cr, Hg, Ni and Pb were higher than provisional permissible tolerable weekly intake and permissible tolerable daily intake while THQ for As, Cd, Cr, Hg, Pb, Se and Zn was higher than 1. The THQ for As, Hg and Pb was several folds higher than 1, indicative of lifetime non-carcinogenic health risks to the consumers. The hazard index indicated cumulative risk, which greatly increased with increasing fish consumption. Target cancer risk indicated that the people eating the Catla catla from Mangla Lake were exposed to As, Cd, Cr, Ni and Pb with a significant lifetime carcinogenic risk. In summary, consumption of Catla catla from this lake was found to be associated with an increased lifetime risk to the general health of the consumers.

Integrated approaches to mitigate threats from emerging potentially toxic elements: A way forward for sustainable environmental management

Potentially toxic elements (PTEs) such as toxic metal (loid)s and other emerging hazardous contaminants, exist in the environment and poses a serious threat. A large amount of wastewater containing PTEs such as cadmium, chromium, copper, nickel, arsenic, lead, zinc, etc. Release from industries during production process. Besides these, chemical-based fertilizers used in soils during crop production have become one of the crucial sources of PTEs. Various techniques are being employed for the mitigation of PTEs like chemical precipitation, ion exchange, coagulation, activated carbon, adsorption, membrane filtration, and bioremediation. Among these mitigation strategies, biological processes such as bioremediation, phytoremediation etc. Are extensively used, as they are economic have high-efficiency rate and are eco-friendly. This review intends to provide information on PTEs contamination through various sources; along with the toxicity of metal (loid)s with respect to their patterns of transmission and risks in the changing environment. Various remediation methods for the management of these pollutants along with their techno-economic perspective are also summarized in this review.

Effect of elemental composition assigned to antrotopic pollution on the quality of the water and sediment of the Marrecas river (PR, Brazil) as highlighted by multivariate statistical analyses

In recent years, several environmental pollutants have been monitored in surface waters and sediments. However, few studies apply multivariate statistics to identify the main components and correlate them temporally and spatially. In this sense, the present study sought to monitor the quality of water and sediments in the Rio Marrecas/Brazil, through the analysis of physicochemical parameters and trace elements, as well as to identifying sources of contamination, using multivariate statistics. For this purpose, sampling was carried out in nine locations for a period of 12 months. The Total Reflection X-ray Fluorescence (TXRF) technique was used to quantify the 15 elements identified in water and sediment samples. Through multivariate statistical analyses, the most significant elements, their correlations and possible pollutant sources were defined, and the pollution index (HPI) and assessment index (HEI) of heavy metals were applied. The parameters pH and BOD₅ do not comply with Brazilian legislation. Based on PCA and Spearman correlation, there was strong evidence of contamination of the water naturally, composed of the elements Ti, V, Mn, Fe, and of anthropogenic origin composed of the elements Ca, Ni, Cu, Zn. These findings provide insights to determine the impacts of heavy metals on human health and the environment.

Study of the Tagus River and Entrepeñas reservoir ecosystem around the Trillo nuclear power plant using chemometric analysis: Influence on water, sediments, algae and fish

The fluvial and aquatic ecosystem of the Tagus River and Entrepeñas reservoir located in the surrounding of the Trillo nuclear power plant (NPP) was evaluated from 1992 to 2008, considering the physical-chemical characteristics, metal content and radiological activity of the water, sediments, algae and fish. The water of both basins demonstrated pH, conductivity, COD, NO₃^- and DO values within a range considered as good quality and the water quality index (WQI) was found to be within a range of 71-90. Chemometric analysis revealed a shift in the river water (from upstream to downstream) affected by the concentration of salts and metals of natural origin, such as Fe and Al, and slight variations in temperature and radiological activity were detected due to the discharges from the NPP. The hydric conditions contributed to increase or decrease the metal concentration of the river water, the reservoir sediments, algae and fish. Fe and Al were found in higher concentration during drought periods and accumulated in sediments, algae and fish along the river course (from SP1 to SP3). Natural and artificial radionuclides found were ⁴⁰K with an average of 245 Bq/kg in river sediments, 499 Bq/kg in reservoir sediments and 121 Bq/kg in fish, and ⁹⁰Sr with a concentration between 0.40 and 1.30 Bq/kg in sediments. Contamination of the aquatic ecosystem with metals and radionuclides was low according to European legislation. In conclusion, this study provides additional elements aimed at understanding the dynamics of fluvial and lentic ecosystems under the influence of different disturbances.

Potential health risk assessment of some bioaccumulated metals in Nile tilapia (Oreochromis niloticus) cultured in Kafr El-Shaikh farms, Egypt

In Egypt, using agricultural drainage water is a serious challenge for fish farming, due to water scaristy. Metals could be a potential threat to the quality of the cultured fish. Thus, this study aimed to assess the content of the metals in the cultured fish, their effect on the fish tissues, and the possible human health risk upon their consumption. This accomplished firstly, by determining the levels of essential Fe, Mn, Zn, Cu, beside the top three most toxic metals (Cr, Cd, and Pb) in the edible muscles and liver of 200 samples of Oreochromis niloticus cultured at three fish farms, using inductively coupled plasma optical emission spectroscopy (ICP-OES). The results showed the order of abundance: Fe > Zn > Cu ≥ Cr > Mn > Pb > Cd. Levels of Fe, Zn, Mn, and Cu in the fish liver were higher than corresponding values of muscles by 3, 3, 5, 9 order of magnitude, respectively. The histopathological examination showed alternations in muscles and liver tissues of fish farms irrigated with drainage water. However, the risk assessment indicated the safe human consumption of cultured fish produced from these fish farms.

Heavy metals bioaccumulation in marine cultured fish and its probabilistic health hazard

In aquacultures, heavy metals could be accumulated in fish tissues from natural and human-related sources depending on different factors. This study aims to estimate the level of bioaccumulation of heavy metals in cultured Gilt-head sea bream Sparusaurata. In this regard, heavy metals concentrations were measured in both water and fish musculature that were collected from a private fish farm in Kafr ElSheikh, Egypt. Regarding the water samples, heavy metals were within the permissible limits with exception of Cd, Cu, and Zn. In fish musculature, all heavy metals were within the WHO/FAO permissible limits. The bioaccumulation factor (BAF) indicated that mostly all heavy metals accumulation in the Gilt-head sea bream musculature decreased with time which may be correlated with the increase in water pH, calcium, and other cations concentrations. The hazard index (HI) calculations indicate no adverse health effects of heavy metals on humans through daily fish consumption so far. However, health risks are not negligible making the regular monitoring of metal contaminants in the studied area a necessity.

Significant Decrease in Heavy Metals in Surface Sediment after Ten-Year Sustainable Development in Huaxi Reservoir Located in Guiyang, Southwestern China

In the Karst area of southwestern China, the heavy metals in the sediment of a reservoir are determined by both human activities and the high background values. Thus, this study explores the change of heavy metals in surface sediment after ten-year sustainable development in the upstream areas of a reservoir, Huaxi Reservoir, located in Guiyang of southwestern China, then evaluates the risk of these heavy metals to water environment systematically and finally identifies the sources in both 2019 and 2009. The results reveal that all of the measured heavy metals decrease dramatically and their spatial distributions change from the increase-decrease pattern to decrease-increase pattern, implying different locations of main source input. The risk indices based on the total or average content and relative or reference values have decreased to the lowest level. However, those indices calculated from the absolute content of each metalloid still show a low or a moderate risk because of the high background value, such as As and Cr. Moreover, although only one main source of heavy metals is identified in both 2019 and 2009, the risk from human activities still cannot be neglected because agricultural production and infrastructure construction would promote the weathering of soil and then these heavy metals from the soil will be brought into the reservoir with the rainfall-runoff process. The high background value of specific heavy metals, e.g., As and Cr would still exert some challenges to the water environment protections because the non-point source input of heavy metal cannot be controlled easily by promulgating a series of bans. These results provide important reference for creating the policies of water environment protection, especially in some Karst area of southwestern China that exhibits high background value of heavy metals.

Metal bioavailability, toxicity, and ecological risk due to sediments of a lately rehabilitated lake (Mariut, Egypt)

Sediments from Lake Mariut, Egypt, after its rehabilitation, and its anoxic diverted polluted drains were subjected to five sequential steps to define different geochemical fractions of eight studied metals. Results cleared out that 30-50% of its total Cd and total Co contents are easily bioavailable with a high-risk assessment code (RAC) to enter the food chain in the lake basin. Whereas Cu and Fe are safe and the remaining studied metals, i.e., Mn, Zn, Pb, and Cr are of medium risk for the environment. Individual contamination factor (ICF) is high (> 6) for all the studied metals except for Fe and Cu which are tightly held in sediments confirming their safeness to biota. Cadmium accounted for > 94% of the total risk in the study area. Metal pollution loading (MPL) from the sediments was found in the order: Fe > Mn > Zn > Pb > Cu > Cr > Co > Cd.

Possible human health risk of some heavy metals from consumption of tilapia fish from Lake Mariut, Egypt

Lake Mariut Main Basin (MB) is not only one of the three basins composing Lake Mariut (LM) but is also the main source of the popular tilapia fish to Alexandrian people. Unfortunately, this basin was consistently for about 50 successive years receiving a continuous discharge of agricultural, sewage, and industrial effluents. This has led to contamination of the flesh of its tilapia fish living there particularly with some toxic heavy metals like Cd and Pb. Lately, in 2010, a rehabilitation program was adopted and carried out to save this vital MB from such intensive pollution. This had been achieved by diverting all those polluting sources. The present work is made after elapsing about 7 years from the diversion process date, to assess and evaluate the levels of those two metals (in addition to the other four one's Fe, Cu, Cr, and Zn) in the edible flesh part besides the liver and gills of this fish (Nile tilapia spec., Oreochromis niloticus), and in ambient water of this restored basin to measure the efficiency of the rehabilitation program on quality of endogenous fish. A simultaneous parallel sampling program was also commenced for the other two basins of LM. The obtained results revealed that the concentration level of the studied metals in each of the muscles of the fish and the ambient water of the restored MB becomes now not only almost alike the metal levels of the corresponding compartments of the other two basins of LM, but also they became at concentration levels lay below those of their counterpart permissible limits in fish and water recommended by national and international standards. Health risk assessment indices: bioaccumulation factor (BAF), metal pollution index (MPI), estimated daily intake (EDI), hazardous index (HI), and relative risk (RR) for the present case were estimated, assessed, and subsequently evaluated. All are referring to a fact that MB is currently in good environmental condition and producing safe fish for human consumption.