Assessment of hydrochemical characteristics, health risks and quality of groundwater for drinking and irrigation purposes in a mountainous region of Pakistan.

Renowned for its agriculture, livestock, and mining, Zhob district, Pakistan, faces the urgent problem of declining groundwater quality due to natural and human-induced factors. This deterioration poses significant challenges for residents who rely on groundwater for drinking, domestic, and irrigation purposes. Therefore, this novel study aimed to carry out a comprehensive assessment of groundwater quality in Zhob district, considering various aspects such as hydrochemical characteristics, human health risks, and suitability for drinking and irrigation purposes. While previous studies may have focused on one or a few of these aspects, this study integrates multiple analyses to provide a holistic understanding of the groundwater quality situation in the region. Additionally, the study applies a range of common hydrochemical analysis methods (acid-base titration, flame atomic absorption spectrometry, and ion chromatography), drinking water quality index (WQI), irrigation indices, and health risk assessment models, using 19 water quality parameters. This multi-method approach enhances the robustness and accuracy of the assessment, providing valuable insights for decision-makers and stakeholders. The results revealed that means of the majority of water quality parameters, such as pH (7.64), electrical conductivity (830.13 µScm-1), total dissolved solids (562.83 mgL-1), as well as various anions, and cations, were in line with drinking water norms. However, the water quality index (WQI) predominantly indicated poor drinking water quality (range = 51-75) at 50% sites, followed by good quality (range = 26-50) at 37% of the sites, with 10% of the sites exhibiting very poor quality (range = 76-100). For irrigation purposes, indices such as sodium percent (mean = 31.37%), sodium adsorption ratio (mean = 0.98 meqL-1), residual sodium carbonate (- 3.15 meqL-1), Kelley's index (mean = 0.49), and permeability (mean = 49.11%) indicated suitability without immediate treatment. However, the magnesium hazard (mean = 46.11%) and potential salinity (mean = 3.93) demonstrated that prolonged application of groundwater for irrigation needs soil management to avoid soil compaction and salinity. Water samples exhibit characteristics of medium salinity and low alkalinity (C2S1) as well as high salinity and low alkalinity (C3S1) categories. The Gibbs diagram results revealed that rock weathering, including silicate weathering and cation exchange, is the primary factor governing the hydrochemistry of groundwater. The hydrochemical composition is dominated by mixed Ca-Mg-Cl, followed by Na-Cl and Mg-Cl types. Furthermore, the human health risk assessment highlighted that fluoride (F-) posed a higher risk compared with nitrate (NO3-). Additionally, ingestion was found to pose a higher risk to health compared to dermal contact, with children being particularly vulnerable. The average hazard index (HI) for children was 1.24, surpassing the allowable limit of 1, indicating detrimental health effects on this subpopulation. Conversely, average HI values for adult females (0.59) and adult males (0.44) were within safe levels, suggesting minimal concerns for these demographic groups. Overall, the study's interdisciplinary approach and depth of analysis make a significant contribution to understanding groundwater quality dynamics and associated risks in Zhob district, potentially informing future management and mitigation strategies.

Ecological risk assessment, source identification and spatial distribution of organic contaminants in terms of mucilage threat in streams of Çanakkale Strait Basin (Türkiye).

In this study, the spatial distributions of organic contamination stressors in water of fluvial habitats in the Çanakkale Strait (ÇS) watershed were investigated and the data were assessed in terms of human health and mucilage threat. Seven significant riverine ecosystems flowing into the ÇS were defined in the basin. Water samples were taken in the spring season (2023), when the phytoplankton communities reach their highest densities. Then they were tested for a total of 8 limnological parameters. The Nutrient Pollution Index (NPI) and Water Quality Index (WQI) were applied to assess the comprehensive quality characteristics of waters. The Hazard Quotient (HQ) and Hazard Index (HI) were applied to indicate the prospective non-carcinogenic human health risks of organic stressors. Principal Component Analysis (PCA) and Cluster Analysis (CA) were applied to categorize the investigated habitats and define the sources of investigated contamination parameters. Also, Geographic Information System (GIS) was used to make an effective assessment through visualization. The determined spatial mean values of the measured variables in ÇS watershed as follows: 18.21 °C for temperature, 8.51 mg/L for DO, 4.57 NTU for turbidity, 3.95 mg/L for suspended solids, 1.11 mg/L for NO3-N, 0.012 mg/L for NO2-N; 0.173 mg/L for PO4-P and 2.32 mg/L for BOD. It has been determined that the organic pollution loads and water temperature values of the investigated sub-basins increase from the upstream to the downstream locations and Çanakkale Stream was recorded as the riskiest fluvial habitat for the ÇS watershed. According to the results of health risk assessment indices, non-carcinogenic risks of organic pollutants would not be expected for all age groups.

Metals and phosphorus in the sediments of streams emptying into the Çanakkale strait (Dardanelles): Spatial distribution, pollution status, risk assessment and source identification.

The Çanakkale Strait is exposed to various pollutants due to its strategic location. It is thought that stream inputs may contribute significantly to metal and phosphorus (P) accumulation in the strait. In this study, the spatial distribution, pollution status, ecological risks and possible sources of twelve metals and P in the sediments of seven important streams emptying into the strait were analyzed. The results showed that Zn (226 mg/kg), Ba (67.2 mg/kg) and Pb (10.4 mg/kg) concentrations were higher in the Umurbey Stream due to mining activities, while P concentration (295 mg/kg) was higher in the Çanakkale Stream due to both agricultural activities and domestic wastewater discharges. Modified hazard quotient (mHQ), enrichment factor (EF) and contamination factor (Cf) values revealed that Zn and Pb showed high and moderate contamination in the US3 and US4 sampling sites of the Umurbey Stream, respectively. Similarly, P showed moderate contamination in the ÇS3 site of the Çanakkale Stream. Nemerow pollution index (NPI) showed that the US3 (2.41) and US4 (4.28) sites of the Umurbey Stream were slightly and moderately polluted, respectively. Toxic risk index (TRI) values demonstrated that the sediments in only the US4 site (5.17) of the Umurbey Stream may pose a low toxic risk due to high Zn content. Similarly, based on comparison results with sediment quality guidelines (SQGs), it was found that high Zn content may lead to adverse effects on sediment-dwelling organisms in the US4 site. In addition, the PEC-quotient value in the US4 site exceeded 0.5, confirming the finding that the sediments in this site could be toxic to benthic organisms. Finally, correlation, cluster and factor analyzes were used to determine possible sources of elements. Mining activities, natural sources and mixed sources (agricultural activities and natural sources) were identified as the main sources of elements in the sediments of the streams. This study can provide an important reference for evaluating stream sediment pollution and managing marine pollution.

Boron contamination and related health risk assessment in the soils collected from olive groves in Izmir province, Türkiye.

Although boron (B) is an essential element for plants, high levels are also toxic. In this respect, pollution of soils by B may pose a serious problem for ecosystem and human health. On the other hand, studies evaluating the ecological and human health risks that may arise due to B contamination in agricultural soils are limited. In this study, it was aimed to determine the B pollution degree of the soils taken from the olive groves of Izmir province, which is approximately 180 km away from the B deposits in the Bigadiç district. In addition, the factors affecting boron adsorption and availability were discussed and the ecological and health risks of boron were evaluated. For this, soil samples were collected at depths of 0-30 cm from 118 olive groves and their B, Al, Fe, pH and organic matter contents were determined. The mean B content (47.08 mg/kg) of the study area was comparable to world-soil average B concentration (42 mg/kg). Also, B had a "low potential ecological risk" in the study area according to the ecological risk index results. On the other hand, based on the results of contamination factor (Cf) and enrichment factor (EF), "moderate contamination" and "significant enrichment" were found in the study area for B. These findings indicated that the B content in the study area is mainly related to the soil parent material, but irrigation water also contributes slightly to B content. Correlation analysis results suggested that Al and Fe contents of the soils in the study area may have an effect on B adsorption. The results of health risk assessment indicated non-carcinogenic effects are not expected for adults and children exposed to soil B content by ingestion, dermal contact and inhalation.

Pollution characteristics, sources and health risks assessment of potentially hazardous elements in sediments of ten ponds in the Saros Bay region (Türkiye).

Pollution of lentic ecosystems by potentially hazardous elements (PHE) due to human activities has become a global concern. In this study, the contents of eight PHEs in the sediments of 10 most important ponds located in the Saros Bay region (Türkiye) were evaluated. The contents of PHEs in the sediments of the ponds ranged from 0.14 mg/kg for Cd to 274 mg/kg for Mn. According to the enrichment factor (EF) results, ponds P3, P8 and P9 for Cd and pond P8 for Pb showed "moderate enrichment". However, the pollution load index (PLI) results indicated that all ponds were in a "baseline contamination" state due to the combined effect of all PHEs. Similarly, based on ecological risk assessment indices, no ecological risk from PHEs was identified. In addition, Cd, Zn, As, Cr, Cu and Pb contents in all ponds were found below threshold effect concentrations. The results of the health risk assessment indicated that non-carcinogenic and carcinogenic risks were not expected for recreational receptors due to exposure to the PHEs in the sediments via incidental ingestion and dermal contact. Correlation and cluster analysis results indicated that although agricultural activities contributed slightly to the As content, all PHEs mainly originated from natural sources.

Hydrochemistry, water quality and health risk assessment of streams in Bismil plain, an important agricultural area in southeast Türkiye.

In this study, the water quality of Ambar, Kuruçay, Pamuk and Salat streams, which are the important tributaries of the Tigris River in the Bismil Plain (Diyarbakir, Türkiye) was assessed using 19 physicochemical parameters. Except for a few exceptions, all parameters in the water samples taken from the streams were below the drinking water limit values. Kuruçay Stream had significantly higher TOC, Na+, NO3-, NO2-, Cl- and SO42- levels and lower DO levels than other streams (p < 0.05) due to sewage water discharges, animal manure storage areas near the stream and irrigation return flows. In all streams, Ca-HCO3 was dominant water type. Gibbs diagram indicated that rock weathering is the major factor controlling the hydrochemistry of the streams. According to the results of water quality index (WQI), all sampling stations of Ambar, Pamuk and Salat streams and K1 station of Kuruçay Stream had "good" quality water for drinking purposes, while K2 station of Kuruçay Stream had "poor" quality water. Irrigation indices (permeability index, sodium percentage, magnesium hazard, residual sodium carbonate, Kelley's ratio, sodium adsorption ratio and potential salinity) revealed that all water samples taken from the streams were suitable for irrigation. The water samples from Ambar, Pamuk and Salat streams were in the C2S1 (medium salinity and low alkalinity) category, while the samples from Kuruçay Stream were in the C2S1 and C3S1 (high salinity and low alkalinity) categories. Both hazard quotient and hazard index values of NO3-N, NO2-N and F- for children and adults were found below 1, indicating that adverse health effects are not expected from exposure to these contaminants via water ingestion and dermal contact. The findings of this study showed that the water quality status of Kuruçay Stream is worse as it receives large amounts of irrigation return flows compared to other streams.

Risk assessment and source apportionment for metals in sediments of Kaptai Lake in Bangladesh using individual and synergistic indices and a receptor model.

Metal enrichment in lake sediments originating from multiple sources can threaten both the aquatic ecosystem and human health. Therefore, assessment of the eco-environmental risks and potential sources of metals in the sediments is essential for effective lake management. Here, we analyzed the sediment metal contents of Kaptai Lake, the largest lake in Bangladesh for the first time with this study. The results indicated that only Cr and Ni contents among the metals studied exceeded the probable effect concentrations (PEC) at 25.42 % and 55.93 % of the sampling stations, respectively. All metals at most sampling stations showed low contamination and low ecological risk based on the individual indices (geoaccumulation index, contamination factor, ecological risk factor, enrichment factor and modified hazard quotient). There was no significant risk from the combined metals in the sediments of the lake according to the synergistic indices (toxic risk index, Nemerow risk index, ecological risk index, Nemerow pollution index and pollution load index). Organic matter and silt were significant sediment parameters that favored the accumulation of Cr, Fe, Cu, Pb and Mn. In the absolute principle component scores-multiple linear regression model (APCS-MLR), five potential sources of metals were identified in the sediments: Zn, Mn, Co and Cd mainly from natural sources and to a lesser extent from agricultural and aquacultural activities, Ni, Cr and Fe from parent materials, Pb and Cu mainly from natural sources and to a lesser extent from vehicle emissions, Hg and U from lithogenic sources, and As from natural sources. This study will improve our knowledge of the sedimentary metal contents of Kaptai Lake and provide helpful information for developing effective lake management and pollution control strategies.

Ecological and health risk assessment and quantitative source apportionment of dissolved metals in ponds used for drinking and irrigation purposes.

In this study, dissolved metal levels of 10 different ponds used as irrigation and drinking water sources in the north of Saros Bay (Türkiye) were evaluated using multivariate statistical methods, contamination and ecological risk indices, and absolute principal component score-multiple linear regression (APCS-MLR). The mean levels of metals in the ponds ranged from 0.045 µg/L (Cd) to 127 µg/L (Mn). Pond 7 used for drinking water source had the lowest total metal level. Only Mn levels in two ponds (P1 and P2) slightly exceeded the critical value set by EU Drinking Water Directive. However, the levels of all metals in all ponds were lower than the critical values set for irrigation water and aquatic life. According to the heavy metal pollution index (HPI), five ponds showed low metal pollution in terms of drinking water quality, four ponds showed moderate metal pollution, and one pond (P1) showed moderate to heavy pollution. According to the Nemerow pollution index (NPI) values (0.26-1.82), ponds P1 and P2 showed slight metal pollution, while other ponds showed insignificant metal pollution. Contamination degree (CD) values of ponds varied between 0.95 and 3.33, indicating that all ponds showed low pollution. In terms of irrigation water quality, all ponds showed low or insignificant metal pollution according to the HPI, NPI, and CD values. According to the ecological risk index (ERI) values, metals in all ponds posed low ecological risks for both drinking and irrigation purposes. Factor analysis identified two potential sources: mixed sources and natural sources. The APCS-MLR model results revealed that mixed sources and natural sources contributed 78.99% and 21.01% to dissolved metals in the ponds, respectively. Health risk assessment results indicated that both individual and combined metals in the ponds would not cause non-carcinogenic risks to both adults and children. Similarly, it was found that Cr and As would not cause carcinogenic risks to the residents of the region.

Evaluation of the water quality of a highly polluted stream with water quality indices and health risk assessment methods.

The water quality of Çorlu Stream, located in the Thrace region of Türkiye, and exposed to intense industrial pressure, was evaluated by monitoring 10 toxic metals and 13 other water quality variables in the dry and wet seasons of 2021. Seven different water quality indices were applied to determine the pollution level at the sampling stations in the stream. In addition, human health risks from exposure to toxic metals in stream water via ingestion and dermal contact were evaluated. The results showed that the water quality at stations S2 and S3 of Çorlu Stream receiving domestic and industrial discharges are seriously polluted by NH4-N, PO4-P, COD, BOD5 and suspended solids according to surface water quality standards. In addition, these stations were highly polluted and had poor water quality according to the results of the water quality indices. The average Cr level at station S3 exceeded the permissible levels set for the protection of aquatic life due to effluent discharges from the leather factories. Considering the results of the health risk assessment methods, non-carcinogenic risks from ingestion of combined metals in stream water can be expected at station S3 for both children and adults and at station S2 for children. Also, it was estimated that Cr and As at station S3 may cause carcinogenic health risks for residents.

Water quality assessment of the Karasu River (Turkey) using various indices, multivariate statistics and APCS-MLR model.

Determining the water quality status of a river and accurately identifying potential pollution sources threatening the river are pillars in effective control of pollution and sustainable water management. In this study, water quality indices, multivariate statistics and absolute principal component score-multiple linear regression (APCS-MLR) were applied to evaluate the water quality of the Karasu River, the main tributary of the Euphrates River (Turkey). For this, 19 water quality variables were monitored monthly at eight stations along the river during one year. Based on the mean dissolved oxygen (DO), electrical conductivity (EC), nitrate-nitrogen (NO3-N), orthophosphate-phosphorus (PO4-P), total phosphorus (TP), ammonium-nitrogen (NH4-N), chemical oxygen demand (COD) and total nitrogen (TN) levels, most stations of the river had "very good" water status according to surface water quality criteria. Spatial cluster analysis (CA) divided eight stations into three regions as clean region, moderate clean region and very clean region. The mean values of Nutrient Pollution Index indicated that the river was "no polluted". Similarly, Water Quality Index and Organic Pollution Index values indicated that the river water quality was between "good" and "excellent". A minimum water quality index (WQImin) consisted of ten crucial parameters was not significantly different with the WQI based on all the 17 parameters. Discriminant analysis (DA) results showed that water temperature (WT), EC, chlorophyll-a (Chl-a), potassium (K), calcium (Ca), NO3-N and COD are the variables responsible for temporal changes, while WT, total dissolves solids (TDS), Chl-a, K, magnesium (Mg), Ca, NH4-N and COD are the variables responsible for spatial changes in the river water quality. Principal component analysis/factor analysis (PCA/FA) identified four potential sources, including anthropogenic, natural, seasonal and phytoplankton. Source apportionment in the APCS-MLR model revealed that seasonal and anthropogenic sources contributed 35.2% and 25.5% to river water quality parameters, respectively, followed by phytoplankton (21.4%) and natural sources (17.9%).

Levels of metals and elements in tissues of fish species in the Kizilirmak River (Turkey) and assessment of health risks and nutritional benefits.

Although the Kizilirmak River, the longest river in Turkey, is home to many fish species, there are a few studies reporting metal levels in fish in the river. The contents of 17 metals and elements (MEs) in various tissues of three fish species and surface water from the river were investigated. Significant differences in the ME levels among tissues were recorded, and the highest levels of most MEs were recorded in the gills and liver. The results revealed that correlations between MEs in tissues and fish size were not clear and consistent. Among the MEs, P (6058-109489) and Zn (933-47556) had the highest bioconcentration factor values. The levels of As and Cd in the river water exceeded water quality criteria. Health risk assessment methods (Target Hazard Quotient, Estimated Daily Intake and Lifetime Carcinogenic Risk) indicated that consumption of the studied fish species is safe. It was estimated that a weekly consumption of 490 g of C. gibelio, or 350 g of C. carpio or 280 g of T. tinca would not cause any health risks. Furthermore, it was found that fish species would provide significant benefits in terms of intake of nutrients such as P, K, Ca, Mg, Cu, Zn, Fe and Mn. These findings revealed that nutritional benefits from consumption of fish species outweigh the health risks posed by metals in fish.

Sediment contamination by trace elements and the associated ecological and health risk assessment: A case study from a large reservoir (Turkey).

Although Keban Reservoir (KR) is Turkey's the second largest man-made reservoir, limited data are available on the contents of trace elements (TEs) in sediments of the KR. The concentrations of 23 less- and commonly-monitored TEs in the sediments from 49 sites in the reservoir were measured to assess health risks, contamination levels and ecological risks of TEs. Concerning median Enrichment Factor values of TEs, chromium (Cr), strontium (Sr) and nickel (Ni) showed moderate enrichment, while other TEs showed minimal enrichment. Pollution Load Index values ranged from 0.33 to 0.63, indicating no a multi-element contamination case in the study area. Low ecological risk was found at 47 sites, while moderate ecological risk was recorded at two sites. The PEC (probable effect concentration) values were exceeded for Ni and Cr. Although wastewater from leather processing factory partly contributed to Cr enrichment at site 2, all TEs mainly originated from lithogenic sources. Median hazard quotient (HQ) values of zirconium (Zr) and lanthanum (La) for children from sediment ingestion were above the risk threshold of unity (HQ = 4.81 and 1.39) and contributed 62.9% and 18.2% of the total health risk. Such high HQ values of Zr and La have never been reported in the literature. Hazard index values for children exceeded those for adults, indicating that children are more vulnerable to health risks than adults. Carcinogenic risk values of arsenic (As) were within the acceptable limits. Our findings indicated that in a multi-element sediment study, some less-monitored elements such as Zr and La may have an important role in health risk assessment even if they are found in the sediment at low concentrations. Therefore, this study can be a model for future similar studies evaluating the health risks of multi-elements in sediments.

Seasonal variations of toxic metal(loid)s in groundwater collected from an intensive agricultural area in northwestern Turkey and associated health risk assessment.

Ipsala district located in the northwest of Turkey is an intensive agricultural area, where paddy cultivation has been carried out for more than 50 years. The main source for drinking water in the area is groundwater. Since large amounts of agrochemicals are applied to the paddy fields, groundwater in the study area can be contaminated with toxic metal (loid)s (TMs). In this study, levels of eight TMs in the drinking water samples taken from the district and its 22 villages in the dry and wet seasons were measured and compared with drinking water quality guidelines. In addition, non-carcinogenic and carcinogenic health risks, and pollution status of TMs were assessed. The mean values of Cd, Ni, Cu, Zn, Mn, Pb, As and Cr in both seasons were below the drinking water limits. High clay content and low infiltration rate of the soils in the study area may have caused low TM concentrations. The TMs levels were higher in the wet season due to high rainfall intensity. Metal pollution indices indicated that groundwater quality is suitable for potable uses. All hazard quotient and hazard index results for children and adults in both seasons were lower than the acceptable risk level of 1. Carcinogenic risk results of As and Cr in both seasons were within or below the acceptable risk range. These findings revealed that the TMs in the drinking water would not pose health risks to the local residents.

Arsenic and trace metal concentrations in different vegetable types and assessment of health risks from their consumption.

The levels of 12 trace metal (loid)s (TMs) in 10 vegetable types including leafy vegetables (purslane, purple basil and parsley) and fruiting vegetables (pepper, tomato, eggplant, cucumber, zucchini, green bean and melon) and in maize grown in Malatya province (Turkey) were investigated and non-carcinogenic health risks from consumption of these crops were assessed. The levels of TMs were measured by inductively coupled plasma-optical emission spectrometry. The mean levels of Ni, Cu, Cd, Cr, As and Zn in all crops were below maximum permissible concentrations (MPCs), while those of Pb in pepper (0.109 mg/kg fw), eggplant (0.103 mg/kg fw) and green bean (0.177 mg/kg fw) slightly exceeded MPCs (0.1 mg/kg fw). Leafy vegetables had relatively higher concentrations of Al, As, Ba, Cr, Cu, Fe and Mn compared to fruiting vegetables and maize. The estimated daily intake value of each TM estimated for each crop was found to be below the tolerable daily intake value. The target hazard quotients of all TMs in all crops did not exceed the acceptable non-carcinogenic risk level. However, hazard index (HI) value (1.57) in tomato was found to be above the threshold value of 1, indicating non-carcinogenic risks for consumers due to the intake of combined TMs in tomato. The THQ values of As, Co and Pb contributed 46.4%, 24.5% and 16.4% of the HI value of tomato, respectively. High daily consumption amount of tomato likely resulted in high HI value. The findings obtained in this study reveal that even if the levels of TMs in vegetables are safe, more attention should be paid to non-carcinogenic risks associated with TMs as a result of high vegetable intake.

Pollution status, potential sources and health risk assessment of arsenic and trace metals in agricultural soils: A case study in Malatya province, Turkey.

We measured the concentrations of arsenic and 11 trace metals in the soils from vegetable fields in Malatya province (Turkey) and assessed health risks for residential adults and children. Also, we assessed their potential sources, contamination status and ecological risks. Median concentrations of only As, Co, Ni and Cr exceeded the world soil average values, while those of Cd, As, Ni and Cu exceeded the upper continental crust contents. Contamination factor, enrichment factor and geoaccumulation index results indicated that the study region was contaminated with Cd, As, Ni and Cu likely due to use of irrigation water contaminated with industrial wastewaters and use of fertilizers and pesticides. Also, the study region had "high potential ecological risk" for Cd, whereas "low potential ecological risk" for the other trace metal(loid)s (TMs). Factor and hierarchical cluster analyses revealed that As and Cu were from anthropogenic sources, Cd and Ni from both natural and anthropogenic sources, while other TMs from natural sources. The hazard quotient values of all TMs and total hazard index values for both children and adults were lower than the risk level of 1, indicating that non-carcinogenic health risks are not expected for residents. Also, the cumulative carcinogenic risk results were within the acceptable risk range. Our results indicated that application of multivariate statistics, pollution, ecological and health indices together provide valuable knowledge for assessing soil pollution in a particular region.

A comparison of trace element concentrations in surface and deep water of the Keban Dam Lake (Turkey) and associated health risk assessment.

Keban Dam Lake (KDL) is the second largest dam lake in Turkey. There have been some reports on the trace element (TE) levels in surface water of the KDL, but its deep water has been never studied. We measured 17 TEs (Pb, Hg, Cd, As, Cr, Ni, Co, Mn, Cu, Fe, Al, Sr, U, V, Zn, Zr and Ba) in surface and deep water samples and assessed their health risks for residential and recreational receptors. Copper, Zn, Ba, Ni, Mn and Pb levels in deep water were higher than those in surface water. Total TE level in deep water was higher in wet season, whereas that in surface water was higher in dry season. TE levels in both surface and deep water were much lower than the guideline values for drinking water and the protection of freshwater aquatic life, indicating that TEs in the KDL originate from natural sources. All HQ (hazard quotient) and HI (hazard index) values were below the risk threshold of unity. HI values for child were higher than those for adult, indicating that the health of children is at dramatically higher risk than adults. Arsenic and U for water ingestion were the primary contributors to total risk (HI), while V and Cr for dermal pathway. The presence of U and V, among the TEs which are major contributors to total health risk, reveals the necessity of monitoring of such less-studied elements in the surface water bodies. Carcinogenic risk values of As and Cr in surface and deep water were below the target risk of 1 × 10-4. These findings indicated that TEs in surface and deep water of the KDL do not pose health risks to residential and recreational users. Thus this study may serve as a model for similar studies assessing health risks of multi-elements in freshwater bodies in future.

Accumulation of trace elements in muscle, gill and liver of fish species (Capoeta umbla and Luciobarbus mystaceus) in the Tigris River (Turkey), and health risk assessment.

Two fish species (Capoeta umbla and Luciobarbus mystaceus) were collected from the Tigris River (Turkey), and tissues (gill, muscle and liver) of fish samples were analyzed for Cd, As, Mn, Cr, Cu, Co and Ni using the inductively coupled plasma-tandem mass spectrometry. Significant differences were present between fish species in regard to trace element (TE) concentrations in muscle for Mn, in liver for Cu, Cd and Mn, and in gill for As, Co, Cu and Cd (p < 0.05). Liver had the highest total TE concentration, followed by gill and muscle. Significant negative correlations were recorded between fish size (length and weight) and TE concentrations in the tissues. Both fish species showed no gender differences in TE accumulation in muscle, gill and liver (p > 0.05). The estimated daily intakes for all TEs were much lower than the tolerable daily intakes. The target hazard quotient (THQ) and total THQ values of all TEs did not exceed 1, which means that non-carcinogenic health effects are not expected for the consumers. Arsenic carcinogenic risk values were within acceptable range. Mean Cd concentrations in muscle tissue of both fish species exceeded the maximum permissible limit set by the European Commission Regulation, while mean concentrations of As, Cr and Cu were below the legislated limits.

Macroelements and toxic trace elements in muscle and liver of fish species from the largest three reservoirs in Turkey and human risk assessment based on the worst-case scenarios.

Macroelement (Na, K, Ca, Mg and P) and toxic trace element (As, Cd and Pb) contents were investigated in muscle and liver of the two fish species (common carp and trout barb) from the largest three reservoirs (Atatürk, Keban and Karakaya) in Turkey. Also, human health risks for consumers using the worst-case scenarios were assessed. Potassium was the most abundant macroelement in muscle of both fish species in all reservoirs, whereas phosphorus was the most abundant in liver. Toxic trace element contents in the liver of the two fish species from the three reservoirs were higher than those in muscle. The mean levels of As and Pb in muscle and liver of fish species from the Karakaya Reservoir were higher than those from the other two reservoirs. Three-way ANOVA showed that the interaction between fish species, reservoir and fish tissue was significant for only Cd (p < 0.01). The maximum levels of As, Cd and Pb in muscle and liver of fish species from the three reservoirs were below permissible limits. The estimated daily intakes of toxic trace elements in fish species were much lower than their corresponding tolerable daily intakes. The target hazard quotient (THQ) and total THQ values in fish species were below 1, which indicated that non-carcinogenic health effects are not expected. The carcinogenic risk values for inorganic arsenic were within acceptable range. The results revealed that toxic trace elements in common carp and trout barb from the Atatürk, Keban and Karakaya reservoirs do not pose a significant health risk to consumers.

Arsenic and trace metals in a large reservoir: Seasonal and spatial variations, source identification and risk assessment for both residential and recreational users.

The Keban Dam Reservoir in Turkey is an internationally important reservoir, because it is located on the Euphrates River, which is an important transboundary river. Water samples were seasonally collected from 11 sampling sites on the reservoir between autumn 2014 and summer 2015. Spatial and seasonal variations, possible sources and health risks of dissolved trace metals (TMs) were investigated. Among ten TMs, only Cr and Mn showed significant spatial variations, while Cr, Mn and Pb did not show significant seasonal variations. The average concentrations of TMs except As and Cd indicated a decreasing trend from autumn to summer. Also, minimum total metal concentration was recorded in summer due to raised water level of the reservoir. Maximum concentrations of all TMs were lower than the drinking water guideline values set by EC (European Community), WHO and USEPA. Principle component analysis/factor analysis and correlation analysis demonstrated that all TMs originate from natural sources. Non-carcinogenic and carcinogenic risks through ingestion and dermal contact exposure pathways were estimated for both residential and recreational receptors exposed to TMs in reservoir water. Hazard quotient, hazard index (HI) and total HI values were lower than 1. Also, carcinogenic risk (CR) values of As and Cr for each exposure route and total CR values were within the acceptable range of 10-4 and 10-6. Thus, the Keban Dam Reservoir is safe for human health in terms of residential and recreational uses.

Comparison of heavy metal levels of farmed and escaped farmed rainbow trout and health risk assessment associated with their consumption.

In this study, levels of ten metals (arsenic, cadmium, cobalt, chromium, copper, iron, manganese, nickel, lead, and zinc) in muscles of farmed and escaped farmed rainbow trout (Oncorhynchus mykiss) in the Keban Dam Reservoir (Turkey) were determined. Also, human health risks associated with their consumption were assessed. Of ten metals, only Co and Fe levels in escaped rainbow trout were significantly higher than those in farmed rainbow trout. The metal levels in farmed and escaped rainbow trout were below the maximum permissible limits. The estimated daily intake (EDI) of each metal in both farmed and escaped farmed rainbow trout was much lower than the respective tolerable daily intake (TDI). The target hazard quotient (THQ) values for individual metal and the total THQ values for combined metals were lower than 1 in both farmed and escaped rainbow trout, indicating no health risk for humans. The cancer risk (CR) values estimated for inorganic As in both farmed and escaped rainbow trout indicated low carcinogenic risk to the consumers. According to the maximum allowable monthly consumption limits (CRmm), adults may safely consume 24 meals of farmed rainbow trout per month or 39 meals of escaped rainbow trout per month, with minimal adverse carcinogenic and non-carcinogenic health effects. This study revealed that the risk from consuming farmed and escaped farmed rainbow trout in the Keban Dam Reservoir due to these trace elements is minimal.