Assessment of the Ecological Risk Associated with Seasonal Variability in Water and Sediment Contamination by Heavy Metals along the Coast of Senegal

The entrance of heavy metals through human activities causes pollution of water, soil, and plants. The aim of this study was to measure the heavy metals concentration (Hg, Pb, As, and Cd) and their ecological impacts on water, soil, and vegetables in the Kashaf Roud River basin. Hence, 72 samples of irrigation water, 72 samples of soils, and 216 samples of vegetables (dill, leek, and basil) were collected. The contamination levels were evaluated by several ecological indices including Ecological Risks index (ERI), Heavy Metal Evaluation Index (HEI), Contamination factor (Cf), Pollution Index (PI), geo-accumulation index (Igeo), Potential ecological risk index (RI), Pollution load index (PLI), and modified degree of contamination (MDC). Based on obtained results, concentrations of heavy metals in water and soil samples were in the order of Pb>As>Cd>Hg. In addition, Pb and As had the highest concentration in vegetables with the mean total concentrations of 1.60 and 0.08 mgkg−1 wet weight, respectively. According to ERI value (238), water sampling site no. 3 had higher pollution than other places and was classified in the considerable ecological risk. Among the soil samples, the Cf average values followed the declining order of Cd (7.78)>Pb (6.91)>Hg (4.26)>As (2.68), so that Pb and Cd presented high contamination levels. Moreover, all soil samples of the studied region possessed PLI>1, which confirms their contamination with heavy metals. Finally, the trends in the BAF values for heavy metals in various vegetables were in order of Hg>Cd≈Pb>As for Leek and Hg>As> Pb>Cd for Dill and Basil. Concentrations of heavy metals in soil and water samples were within the national and international standard ranges. However, the concentrations of these metals in some vegetable samples exceeded the national and international levels. The utilisation of standard quality effluent for agricultural irrigation requires control measures and good organisational performance.

Pollution of water and soils by heavy metals is an emerging problem in industrialized countries. The present study was conducted to investigate the heavy metals concentration in water and sediment samples from ship breaking sites of Sitakunda to assess the potential ecological risk posed by heavy metal using different methods. Heavy metals concentration was analyzed by Atomic Absorption Spectroscopy. Concentrations of all the tested heavy metals except Cr in water samples of ship breaking site, Sitakunda were lower than recommended values. The mean concentration of Cr was found 0.511± 0.284 mg/l. Concentrations of all the tested heavy metals except Mn in sediment samples were higher than standard limit. The concentrations of Pb, Mn, Cr, Cu and Zn in the sediment were 55.93±18.70, 20.08±4.03, 106.8±47.65, 50.09±18.31, and 70.71±19.45 mg/kg, respectively. Based on Geoaccumulation Index, Contamination factor, Sediment Quality Guidelines, the sediment of ship breaking site can be treated as unpolluted to moderately polluted with Pb, Zn, Cr and Cu but unpolluted with Mn. The Enrichment factors of Pb, Mn, Cr, Cu and Zn in the sediment were: 2.97±0.98, 0.035±0.008, 1.97±0.88, 1.99±0.73, and 1.17±0.32, respectively. The Enrichment factor (>1) in all sampling sites, suggesting source of those metals (Pb, Cr, Cu and Zn) were more likely to be anthropogenic. Based on the Potential Ecological Risk Index the ship breaking site posed to low risk to the environment. The results of present study clearly indicated that the ship breaking site was moderately polluted with heavy metals and pose low risk to the ecosystem.

With rapid developments in society and economy, the concentrations of heavy metals in surface water in South China have increased significantly, which poses a serious threat to the regional water security. In this study, the Fuhe River watershed in South China was selected as the study area to analyze physicochemical characteristics and heavy metal (Cu, Zn, Pb, Cd and Cr) concentrations in river water in the dry and rainy seasons, in 2019, with the purpose of exploring their spatial–temporal variations and main influences and assessing the potential health risks of heavy metals. The pH value of river water varied from 5.82 to 7.97, and it fluctuated less overall in the dry season, but it oscillated greatly in the rainy season and was lower, especially in the lower reach of the Fuhe River. The electrical conductivity (EC) value changed between 33 μS/cm and 128 μS/cm and increased and fluctuated along the river flow in the two periods. The concentrations of Cd, Cr, Cu, Pb, and Zn in river water showed obvious differences between the two periods. The concentrations of Cd and Cu were lower with the ranges from 0.001 μg/L to 0.67 μg/L and from 1 μg/L to 12 μg/L, respectively, in the dry season than in the rainy season, while there were inverse cases for other heavy metals. Along the river flow, the Cr concentration was stable, whereas other heavy metals showed increasing trends. It was noted that the concentrations of heavy metals in the Fuhe River were, on average, lower than the Chinese drinking standard values, with the concentration of Pb in the dry season significantly higher than the drinking standard value of the World Health Organization (WHO). Principal component analysis and correlation analysis showed that rock weathering and anthropogenic inputs were the main controlling factors of Cu and Zn in the Fuhe River, and human activities were mainly responsible for Pb, Cr, and Cd concentrations. The health risk assessment results showed that the non-carcinogenic risk (HQingestion) value of Pb was greater than 1 in most sampling points in the middle and lower reaches in the dry season, suggesting a significant non-carcinogenic risk for adults and children by direct ingestion. The minimum carcinogenic risk (CRingestion) value of Cr was more than 10−4 in the rainy and dry seasons, and the CRingestion value of Cd in some sampling points was more than 10−4 in the rainy season, indicating significant cancer risks to adults and children. For areas with significant pollution and health risks in the Fuhe River watershed, it is urgent to strengthen the controls of industrial, agricultural, and urban wastewater discharge.

The occurrence of heavy metals in water ecosystems and sediment can impact human life, due to their possible transfer to food chain and adverse effects. Therefore, it is crucial the evaluation of the status of heavy metals in water and sediments in order to evaluate water quality and their environmental impacts. Current study aims to evaluate the occurrence of heavy metals in water and sediment as well as the water and sediment pollution of Drini Bardhe River in Kosovo. Three representatives sampling sites were selected along Drini Bardhe River to collect water and sediment samples. Heavy metals concentrations in water and sediment samples were determined by using atomic absorption spectrophotometer (AAS). The data of heavy metal concentration in water were compared with EC Directives 75/440/EEC and 2008/105/EC in order to evaluate water quality. The degree of sediment pollution was evaluated by using Enrichment Factor (EF) and Geo-accumulation Index (Igeo). Based on obtained data of heavy metals concentration in water, the values of iron and arsenic were over acceptable values of EC directives. Enrichment factor (Ef) calculations showed that sediments have moderate severe enrichment for Cd and Ni, minimal enrichment for Cu, Cr, and Pb, whereas no enrichment for Fe, Mn and Zn. Based on Geo-accumulation Index (Igeo) calculations sediments result strongly polluted with Cd and Ni, moderately polluted with Cr, unpolluted to moderately polluted with Cu, Mn, Pb and Zn, and unpolluted with Fe. The Occurrence of heavy metals in water and sediments indicates potential risk of some heavy metals as their amounts were over acceptable limits. Keywords: Heavy metals, Ef, Igeo, pollution, water, sediment.

Seasonal assessment of heavy metal concentration (Cu, Zn, Fe, Mn and Ni) in water of Rupingazi River was carried out during the wet season in May (2018) and dry times in January (2019). In this research water samples were collected from twenty sampling points along the river. The levels of the heavy metals in the water were measured with the Atomic Absorption spectrophotometer. Data that was obtained from the analysis of the water was analyzed using one-way analysis of variance. Mean heavy metal concentrations (mg/l) in water were Cu (0.01-0.31), Fe (0.00-1.82) and Zn (0.003-1.508) during the wet season and Cu (0.01-0.40), Fe (0.53-2.07) and Zn (0.02-1.81) during the dry season. The levels of zinc and copper were lower than the WHO limits for drinking water. Iron levels in most sampling stations either during the wet or dry season exceeded the limits. Analysis of the correlation coefficient showed a low, moderate or high correlation between the heavy metals in water during both seasons. Key words : heavy metal, concentration, water, Rupingazi river, pollutants DOI : 10.7176/JNSR/15-3-05 Publication date : November 30 th 2024

Human welfare and biodiversity are at risk due to the deterioration of water and sediment quality. Particularly, in last few decades, global water and sediment quality degraded due to the rapid industrialization and urbanization. This study aimed to determine the concentration of nine heavy metals and metalloid (Pb, Cr, Cd, Hg, As, Mn, Ni, Cu, and Zn) and assess the ecological risks using different pollution indices (e.g., heavy metal pollution index [HPI], Nemerow pollution index [NI], geo-accumulation index [Igeo], contamination factor [CF], degree of contamination [CD] and pollution load index [PLI], ecological risk index [ERI]) in water and sediment of the Shitalakshya River, an industrially affected urban river of Bangladesh. For the first time, 20 water and sediment samples were collected across a wider geographical area of the Shitalakshya River during both monsoon and dry seasons and analyzed using the atomic absorption spectrometer. Average concentrations of heavy metals and metalloid in water were within the Bangladesh standard except for Cr (51.69 ppb) and Mn (228.20 ppb) during monsoon season, portraying potential ecological and human health risks. Besides, average concentration of Mn (549.75 and 370.93 ppb), Ni (549.75 and 370.93 ppb), and Cu (45.34 and 36.09 ppb) in sediment during both seasons were above international standard, implying risk to aquatic sediment biota. The average HPI values indicated moderate to high contamination, whereas the NI values implied polluted water in monsoon season with severe pollution in port area of the river. Similarly, Igeo, CF, CD, and PLI elucidated different levels of contamination in the sediment, particularly during dry season. The ERI values also referred moderate ecological risk in the sediment during dry season. Overall, our findings highlight the alarming level of heavy metal pollution in the Shitalakshya River, necessitating immediate action to protect the aquatic environment, sediment biota, and human health. PRACTITIONER POINTS: This study determined the concentration of heavy metals and metalloid in water and sediment of the Shitalakshya River, Bangladesh. The study revealed that the average concentration of Cr and Mn in water exceeded national standard, whereas Mn, Ni, and Cu in sediment exceeded international limit. Potential ecological risk of heavy metals was also assessed using different pollution indices. Calculated pollution indices indicated different degree of pollution, implying critical ecological condition due to heavy metal pollution in aquatic environment and sediment biota.

Purpose. Assessment of the dynamics of heavy metal accumulation in water, bottom sediments, and fish of water bodies of different purposes in Dnipropetrovsk region. Methodology. The study on heavy metal contents in water, bottom sediments, and hydrobionts (fish) was conducted at various water bodies (Dnipro-Donbas hydraulic canal), fish ponds (ponds of PrJSC “AgroSoyuz”, PrJSC “Petrykivsky Rybhosp” and PE «Agrofirma «Nakhodka»), and multipurpose reservoirs (Dnipro reservoir, Sholokhivske reservoir) in Dnipropetrovsk region from 2015 to 2024. The determination of heavy metal concentrations (Pb, Cd, Mn, Cu, Fe, Ni, Zn) was carried out at the laboratory of the Research Center for Biosafety and Environmental Monitoring of Agricultural Resources of Dnipro State Agricultural and Economic University. The metal content was analyzed using atomic absorption spectrophotometry. The heavy metal contents were measured in four fish species (European perch, roach, Prussian carp, common carp). Sampling, data processing, and statistical analysis were conducted according to standard hydrochemical, hydrobiological, and ichthyological methods. The heavy metal contents were determined in fish muscles. Water quality was assessed according to general requirements and standards for fishery water bodies. Findings. The heavy metal contents in ecosystems of water bodies of different purposes was determined. In the sediment of ponds of PrJSC “AgroSoyuz” and PrJSC “Petrykivsky Rybhosp”, the heavy metal contents were significantly higher than in water or fish body: manganese within 41.24–68.43 mg/kg, cadmium – 0.32 mg/kg, lead 1.50–4.90 mg/kg (for ponds of PrJSC “AgroSoyuz”); manganese – 29.73 mg/kg, cadmium – 0.54 mg/kg, lead 5.72 mg/kg (for recreational pond of PrJSC “Petrykivsky Rybhosp”). For the water of these ponds, which is used for aquaculture, an excess of the content of some heavy metals – Mn, Zn, Cd - was recorded, and for the pond of PrJSC “AgroSoyuz” also Cu. Exceeding the normative heavy metal content for pond water of PE “Agrofirma “Nakhodka” was not noted. The content of some heavy metals in the water of the upper part of the Dnipro reservoir (Cu, Fe) did not meet the fishery norms. At the same time, the heavy metal contents in water and fish of these water bodies does not exceed the fishery standards for water used for fishery purposes. The heavy metal contents in the water of the upper part of the Dniprovske Reservoir (except for the Samara Bay) corresponded to fishery standards. The water in the Dnipro-Donbas hydrotechnical canal was characterized by high levels of heavy metals. Of the 6 investigated heavy metals, the maximum allowable concentrations were not exceeded only for lead (0.40 mg/dm3) The heavy metal contents in C. carpio muscles (juveniles and table fish) in different ponds of PrJSC “Petrykivskyi Rybhosp” (nursery and fattening) corresponded to fishery standards during the three years of the study (2011, 2015, 2016). In the Sholokhivske reservoir, the zinc content in C. gibelio muscles was 46.50 mg/kg, slightly exceeding the maximum allowable concentrations. Exceedances of copper and lead content were not noted. For fish from the Dnipro reservoir, the content of most heavy metals was elevated. In the meat of pelagic roach (R. rutilus), only copper content was within the normal limits (1.56 mg/kg), while all other 6 heavy metals exceeded the maximum allowable concentrations. In the meat of benthophagous Prussian carp (C. gibelio), elevated levels of accumulation of heavy metals were observed for manganese, iron, lead, and nickel, while zinc, copper, and cadmium content were within the standards. In the meat of European perch (P. fluviatilis), the highest content of heavy metals was observed for iron (80.54 mg/kg), with elevated levels observed for manganese, zinc, lead, and nickel. The obtained results indicate that the hydroecosystem of the Dniprovske reservoir, unlike other water bodies in the region, is significantly polluted with heavy metals. This is adequately reflected in the levels of heavy metal accumulation in the organisms of fish from different ecological groups - pelagic herbivores, benthophagous bottom-feeders, and predators. Originality. For the first time, the content of heavy metal accumulation in water, bottom sediments, and fish of water bodies of different purposes in Dnipropetrovsk region has been carried out over several years (2015–2024). Practical Value. The obtained results have theoretical and practical importance for the preparation of scientific-biological justifications for the fishery use of water bodies of various purposes in the region. Continuous monitoring of the heavy metal contents in hydrobionts is necessary to ensure food safety and the quality of raw materials and food fish products. Keywords: Dnipropetrovsk region, heavy metals, Dnipro Reservoir, Dnipro-Donbas Canal, ponds, Sholokhivske Reservoir, water, sediment, fish, accumulation of pollutants.

In this paper, some trace metals were seasonally determined for six months between January -June 2021 (to cover both the wet and dry seasons) in surface water and sediments from River Riana in Kisii County. The river is an important source of drinking water and fisheries and receives an array of wastes from agricultural, industrial, commercial and sewage treatment. Consequently, this study evaluated the levels or concentrations of heavy metals (Pb, Cr. Ni, Mn, Cu and Zn) in surface water and surface sediments and the effect of seasonal variations on their concentrations. Samples were collected monthly from three sampling sites along the River and the results of heavy metal concentrations were compared with national and international guidelines including the Kenya Bureau of Standards, World Health Organization (KEBS/WHO) and WHO sediment quality guidelines (SQGs) respectively to establish pollution level. Metal concentrations in water and sediments were analyzed using inductively coupled plasma atomic emission spectroscopy (Shimadzu ICPE-9000) after nitric acid digestion. The results obtained showed that the mean range of heavy metals in water (ppm) were: Pb (0.031-0.196), Cr (<0.001-0.009), Ni (0.014-0.321), Mn (0.131-0.351). Cu (0.114-0.370) and Zn (0.132-0.326) while the mean range of metals in surface sediments (mg/kg) was; Pb (0.041-8.74), Cr (0.001-1.31), Mn (276-692), Cu (1.35-9.74) and Zn (6.37-15.67) respectively. The heavy metals Cr, Cu and Zn complied with the WHO and KEBS drinking water recommended safe limits while the Pb and Mn concentrations exceed the recommended safe limits but Ni concentrations exceeded KEBS recommend safe limit for drinking water. The mean monthly concentrations for the heavy metals in surface water and surface sediments for the River decreased in the order Mn>Zn>Cu>Pb>Ni.>Cr and Mn>Zn>Cu>Ni>Pb.>Cr respectively. The heavy metal concentrations were generally higher during the dry season than the wet season in both surface water and sediments however, there were no significant seasonal differences (p>0.05) except for Cr and Mn in water. All the heavy metals complied with WHO fresh water SQGs and exhibited no significant seasonal variations (p ≥0.05) in water for surface sediments. The River Riana was contaminated by all the determined trace metals and this indicated potential toxicity risk, thus the need for regular monitoring. We recommended determination of other toxic metals in water, sediments and biota such as fish form this river

Toxic heavy metals get into humans through absorption, inhalation and ingestion. All heavy metals are toxic to animals and plants when present in excessive amounts. The adverse effects of heavy metals in mammals may manifest in disorders such as growth retardation, decrease in longevity, changes in reproductive cycles, chronic diseases and formation of tumours. River Nyamindi flows from Mt. Kenya Forest passing through rocks, soil, agricultural land, residential areas and urban centres. Geological factors and human activities may have made heavy metals get into the river water. Since the water is used for domestic purposes and irrigation, it was necessary to determine if heavy metal concentration in river Nyamindi has reached alarming levels. Water and sediment samples were collected along river Nyamindi during wet and dry season. The samples were digested appropriately and the concentration of eight heavy metals determined using ICP-MS. The mean amount of Cd, Cr, Ni, Pb, Zn, As, Mn and Se in sediment were 0.0882, 41.1219, 91.7718, 10.7445, 54.3880, 2.4561, 1753.5587 and 5.7648 mg/kg respectively during wet season and 0.0590, 39.1176, 559.0917, 0.3781,76.3715, 3.0114, 1714.4195 and 6.5488 mg/kg respectively during dry season. The mean concentration of the same metals in water was 0.00005, 0.0167, 0.1943, 0.0223, below detection limit (BDL), 0.0002, 0.1379 and BDL ppm respectively during wet season and 0.0009, 0.0005, 0.0148, 0.0184, BDL, 0.00003, 0.0080 and 0.00003 ppm respectively during dry season. The mean amount of Cr, Ni and Mn in sediment were found to be above WHO and US EPA permissible limits during both seasons. The mean concentration of Cr and Mn in water were above WHO and KEBS/WASREB permissible limits during wet season. However, during dry season, all the eight heavy metal concentrations in water were below WHO, KEBS/WASREB permissible limits. Therefore, as far as the eight heavy metals are concerned, water from river Nyamindi was not be potable during rainy season but was potable during dry season. However, further investigations should be carried out to determine other water parameters to confirm it’s suitability as potable water.

The indiscriminate dumping of municipal solid waste in Malawi, particularly at Lunzu dumpsite in Blantyre, has raised significant environmental concerns due to the potential contamination of surrounding soils and water sources by heavy metals (HMs). This study assessed the concentrations, spatial distribution, and ecological risks of selected heavy metals, cadmium (Cd), lead (Pb), copper (Cu), zinc (Zn), iron (Fe), manganese (Mn), and cobalt (Co) in soil and groundwater around the dumpsite. Samples were collected at varying distances (0-250 m radius from the dumpsite) during both dry and wet seasons and analyzed using Flame Atomic Absorption Spectrophotometry (AAS). In soil, the highest concentrations were recorded at the dumpsite center during the dry season: Cd at 3.08 mg/kg, Cu at 316.18 mg/kg, and Pb at 80.00 mg/kg, exceeding the WHO and EU permissible limits. In the wet season, metal concentrations were lower but still elevated, with Cd at 2.77 mg/kg, Zn at 635.22 mg/kg, and Pb at 72.00 mg/kg. In water samples, the maximum concentrations during the dry season were Cd at 0.02 mg/L, Pb at 0.14 mg/L, and Fe at 1.56 mg/L, which exceeded WHO drinking water standards, particularly for cadmium and lead. Correlation analysis revealed strong positive relationships among most metals and soil organic carbon (SOC), suggesting common pollution sources and the role of organic matter in metal retention. Water samples also revealed elevated concentrations of cadmium and lead, with levels surpassing WHO, EU, and Malawi Bureau of Standards (MBS) guidelines, posing serious health risks to nearby communities. Contamination assessment indices like the contamination factor (CF), geo-accumulation index (Igeo), enrichment factor (EF), and potential ecological risk index (PERI) consistently identified cadmium and mercury as the most ecologically hazardous metals. The spatial trend showed a decline in metal concentrations with increasing distance from the dumpsite, confirming the dumpsite as the primary contamination source.

We investigated eight heavy metals (Cr, Cd, Cu, Ni, Pb, Zn, Mn, and Fe) in water and bed sediment at 9 study sites along with 2320km stretch of the Ganga River. Principal component analysis (PCA) and indices such as geo-accumulation index (Igeo), contamination factor (CF), enrichment factor (EF), pollution indices, and sediment quality guidelines were used to assess source apportionment and magnitude of contamination. Concentrations of Cr, Cd, Pb, Ni, Cu, and Fe in water have exceeded their respective standards in the middle and lower reaches of the river. Sediment Cr and Ni have reached probable effective concentration (PEC) at Kannauj, imposing likely threats to sediment dwellers. Highest Igeo values were recorded for Cr, Cd, and Pb at Kannauj, Rajghat, and Howrah. We further tested ecological risks (Er) and potential ecological risks (PERI) to assess individual and cumulative effects and found the Kannauj, Rajghat, and Howrah sites under the high-risk category. The modified pollution index (MPI) and the modified degree of contamination (mCd) also revealed the middle and lower river reaches under moderately to the heavily polluted category. Our study provides the first detailed watershed-scale database on heavy metal concentration in water and bed sediment, the magnitude of contamination, and likely ecological risks to aquatic organisms in the Ganga River. Given that the Ganga water is used for drinking and irrigation and the river harbors a diversity of habitats for fisheries, the study merits attention from a human health perspective as well.

The Yacoraite River and its tributaries run down the eastern slope of the Aguilar Range. It is one of the tributaries of the Rio Grande, located in Quebrada de Humahuaca, a UNESCO World Heritage site. The Aguilar underground mine (Pb–Ag–Zn) is located in the upper reaches of the Yacoraite River drainage basin. The aim of this work is to characterize the presence of heavy metals in water and sediments of the Yacoraite River and to identify their sources. The analysis shows the seasonal variation of heavy metals concentration in water and their relation with the World Health Organization (WHO) limits established for human consumption. The Yacoraite basin is naturally anomalous in some metals and some elements, such as As which is controlled by the chemical composition of regional lithology. During the wet season, Al, Co, Mo and Pb concentrations in water samples are higher than during the dry season; in addition, these metals are also higher than WHO limit values. High enrichment factors for Ba, Mo, Pb, Zn and Cd were found in Casa Grande stream, indicating the direct influence of the mining activities. Cd, Pb and Zn are present in the Aguilar ore minerals, such as sphalerite and galena. Sediments collected during the dry season show a drastic increase in the concentration of As, Pb, Ba, Zn, Cd and Mn. The Müller geo-accumulation index in Casa Grande indicates that it is a highly polluted stream. The concentrations of As, Pb, Ba, Zn, Cd are also high in Yacoraite River: Security Quality Guidelines indicates toxicity. A decrease in enrichment factors and geo-accumulation indices observed in sediments indicates the occurrence of precipitation/adsorption processes in the river to restore the equilibrium composition. Strict environmental controls in Aguilar Mine are necessary to avoid the uncontrolled input of toxic metals in Casa Grande stream and Yacoraite River.

Bioaccumulation of heavy metals (cadmium, Cd; chromium,Cr; lead, Pb; copper, Cu) in plankton and water from Elechi creek were studied for twelve months. Plankton and water samples collected using plankton net and bottles were analysed for heavy metals following standard method of APHA and the data obtained were subjected to statistical analysis. Results showed that plankton accumulated more heavy metals than water with the orders of magnitude, Cu> Cd > Cr >Pb and Cu > Cr> Pb> Cd for plankton and water respectively. The mean values of heavy metals in water were lower than the EPA, USEPA and WHO permissible limits for human consumption. Pb concentration in plankton differed significantly in station 4 while Cu differed seasonally with dry season values higher than wet season values unlike the heavy metal concentration in water. The higher bioconcentration factor (BCF) and the order, Cd>Pb>Cr> Cu observed showed that plankton has high potential to concentrate heavy metals. The dominance by Bacillariophyceae followed by Chlorophyceae and Cyanophyceae in species and abundance and the presence of indicator species, Cyclotella species, Melosira monoliformis and Navicula distans indicates pollution. This calls for awareness and constant assessment to avoid further contamination of the resources meant for human consumption.Keywords: Heavy metals, plankton, bioaccumulation, pollution, Elechi Creek

This study examines the levels of heavy metals in polyculture fish (Labeo rohita, Cyprinus carpio, and Catla catla), water, and sediment in Tanda Dam, Kohat, Pakistan, aiming to understand environmental and health risks. Samples of fish, water, and sediment were collected from 3 fish farms, and heavy metal concentrations were measured using a Flame Atomic Absorption Spectrophotometer (AAS). Results reveal that C. catla exhibited significantly higher (p < 0.05) levels of Zn than other fish species. Conversely, C. carpio showed significantly higher (p < 0.05) concentrations of Pb, Cd, Cr, Mn, Cu, As, and Ni than other species. The heavy metal hierarchy in C. carpio was found to be Zn > Cu > Pb > Cr > Cd > Mn > As > Ni. While heavy metal levels in L. rohita and C. catla generally fell within reference ranges, exceptions were noted for Zn, Pb, and Cd. Conversely, in C. carpio, all metals exceeded reference ranges except for Cu and Ni. Principal Component Analysis (PCA) indicated a close relationship between water and sediment. Additionally, cluster analysis suggested that C. catla formed a distinct cluster from L. rohita and C. carpio, implying different responses to the environment. Despite concerns raised by the Geoaccumulation Index (Igeo) and Contamination Factor (CF), particularly for Cd, which exhibited a high CF. Furthermore, Hazard Index (HI) values for all three fish species were below 1, suggesting low health risks. However, elevated Igeo and CF values for Cd suggest significant pollution originating from anthropogenic sources. This study underscores the importance of monitoring heavy metals in water for both environmental preservation and human health protection. Future research efforts should prioritize pollution control measures to ensure ecosystem and public health safety.

The water quality of the Golmud River is essential for environmental preservation and economic growth of Golmud city and Qarhan Salt Lake in China. Thirty-four samples of surface water and sediment from seventeen places in the Golmud River and thirty-two dustfall samples in the Qaidam Basin were collected. The concentrations of heavy metals (HMs) were measured; water quality, risk assessment, and multiple source analysis were applied. Concentrations of HMs in water were Zn &amp;gt; Cu &amp;gt; Ni &amp;gt; As &amp;gt; Pb &amp;gt; Cd &amp;gt; Hg, and in sediment were Ni &amp;gt; Zn &amp;gt; Pb &amp;gt; As &amp;gt; Cu &amp;gt; Cd &amp;gt; Hg. In water, the Nemerow pollution index (NP) values indicated that most of the sampling points seemly were seriously polluted; other water quality assessment results suggested no pollution. In sediment, the concentrations of 27% HMs exceeded the background values of soil in Qinghai; 48% exceeded the Earth crust background values, which were As, Hg, and Cd. The single factor index method (Pi), geological accumulation index (Igeo), and contamination factor (CF) revealed that As pollution is serious, followed by Hg and Cd; the pollution load index (PLI) and modified pollution index (mCd) values indicated that 64% and 57% of samples were polluted. NP values are shown serious pollution. The ecological risk results demonstrated a low risk in water and a medium risk in sediment. The average total hazard quotient values in sediment and water for adults and children revealed low non-carcinogenic risks. Carcinogenic risk indicated Ni in water and sediment, and As in sediment may be involved in cancer risk. Multivariate statistics showed that the HMs mainly came from nature, and human activities will also impact them. The upper continental crust values indicated that As and Hg have high background values. The saline dust storm was one of the essential sources of HMs, especially Hg. Various provenances constituted the material cycling of HMs in the surface environment.