Appraisal of metallic accumulation in the surface sediment of a fish breeding dam in Türkiye: A stochastical approach to ecotoxicological risk assessment.

This study examines the levels and patterns of potentially toxic elements (PTEs) in surface sediment of Almus Dam Lake (ADL), a key fish breeding site in Türkiye. PTE concentrations in sediment were ranked: Hg (0.05 ± 0.01) < Cd (0.16 ± 0.01) < Pb (9.34 ± 1.42) < As (18.75 ± 15.65) < Cu (63.30 ± 15.17) < Ni (72.64 ± 20.54) < Zn (86.66 ± 11.95) < Cr (108.35 ± 36.40) < Mn (1008 ± 151) < Fe (53,998 ± 6468), with no significant seasonal or spatial differences. Ecological risk indices (mHQ, EF, Igeo, CF, PLI, Eri, mCd, NPI, PERI, MPI, and TRI) showed low contamination levels. Health risk assessments, including LCR, HQ, and THI, indicated minimal risks to humans from sediment PTEs. Statistical analyses (PCA, HCA, SCC) identified natural, transportation, and anthropogenic PTE sources, with slight impacts from agriculture and fish farming. This research underlines contamination status of ADL and emphasizes the need for targeted management strategies, offering critical insights for environmental safeguarding.

Spatiotemporal variations, health risk assessment, and sources of potentially toxic elements in potamic water of the Anday Stream Basin (Türkiye), Black Sea Region.

Monitoring and protecting freshwater habitats are paramount for a sustainable water management perspective. This study investigated potentially toxic elements (PTEs) in the potamic water of the Anday Stream Basin (Türkiye), Black Sea Region, for a hydrological year (from May 2020 to April 2021). Among PTEs, the highest average values were recorded for sodium (Na) at 41.3 mg/L and the lowest for mercury (Hg) at 0.009 µg/L and noted under quality guidelines. The stream was found to be at the level of "Low Heavy Metal Pollution" and "Low Contamination" based on the ecotoxicological risk indices. The highest calculated hazard quotient (HQ) value of 1.21E-02 for Cd was noted in the children via the dermal pathway and the lowest of 6.91E-06 for Fe in adults via the ingestion pathway. Results revealed a higher hazard index (HI) value of 1.50E-02 for Cd to children and the lowest of 1.98E-05 for Fe to adults. As a result of applying agricultural risk indices, the stream showed sodium adsorption ratio values less than 6 and was found to be "Excellent" for agriculture. However, the sodium percentage values were less than 20 and found "Permissible" and the magnesium hazard > 50 and noted as "Unsuitable" for agriculture. Statistical analysis revealed that natural factors mainly attributed to PTE contamination of the Anday Stream Basin.

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.

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.

Temporal variation of water quality parameters in the lacustrine of the Thrace Region, Northwest Türkiye.

Thrace is a part of the Marmara Region northwest of Türkiye. This region hosts several lentic ecosystems used for irrigation and drinking water supply. The present study was conducted to analyze the temporal distributions of water quality parameters (WQPs) of lentic ecosystems (lacustrine habitats), including lakes (L1-L2), reservoirs (R1-R12), and ponds (P1-P19) of the Thrace Region. Thirty-three lacustrine habitats were identified in the region. Freshwaters were collected in the wet (end of winter) and dry (end of summer) seasons of 2021-2022 and tested for 12 WQPs. Data was evaluated for the water quality index (WQI) and nutrient pollution index (NPI) and their overall quality level. For the evaluation of non-carcinogenic health risk indices of WQPs, the chronic daily index (CDI), hazard quotient (HQ), and hazard index (HI) were applied. Cluster analysis (CA), Pearson correlation index (PCI), and principal component analysis (PCA) were used to classify the lacustrine habitats and identify the source of WQPs. The average values were as follows: 9.28 mg/L for dissolved oxygen (DO), 94.6% for oxygen (O2) saturation, 9.29 for pH, 613 µS/cm for electrical conductivity (EC), 3.96 NTU for turbidity, 358 mg/L for total dissolved solids (TDS), 3.17 mg/L for nitrate (NO3), 0.05 mg/L for nitrite (NO2), 1.01 mg/L for phosphate (PO4), 78.5 mg/L for sulfate (SO4), and 102 mg/L for chloride (Cl). Results showed a significant increase in WQPs, including NO3, NO2, and PO4, in the wet season, while the salinity decreased from the dry to wet season. Results revealed that HI values of water contaminants in lacustrine habitats were noted to be less than one. Based on determined WQPs, the present study recommends using lacustrine water habitats for irrigation, drinking, and other domestic and industrial purposes.

Spatial distribution of potentially toxic elements contaminations and risk indices of water and sediments in the Darband and Samana streams, Pakistan.

This study examined potentially toxic elements (PTE) of water and sediments in the Darband and Samana streams of Hangu District. Darband and Samana streams are the main fluvial ecosystems of Hangu District, Pakistan, directly or indirectly affecting more than 0.52 Million people. Water and sediment samples were collected and analyzed for PTE utilizing inductively coupled plasma mass spectrometry (ICP-MS). Water characteristics of Darband and Samana streams were noted within the WHO drinking water guidelines, except for Turbidity and sulfate. Most water characteristics showed higher values in the Samana stream than in the Darband stream. Similarly, most of PTE showed higher concentrations in sediments collected from the Samana stream than the Darband stream. For ecological risk evaluation, several pollution indices were employed to assess the eco-toxicological consequences. The highest contamination factor (CF) value of 15 and 20 were exhibited by molybdenum (Mo) in the Samana and Darband streams showing very high contamination. Similarly, the pollution load index (PLI) showed that 24% of the sediment samples were polluted (PLI > 1). Furthermore, a high ecological risk in a range of 160 < ERI < 320 was observed for Mo, while a low ecological risk ERI < 40 was by As for the Darband and Samana streams sediments. Statistical techniques revealed that various anthropogenic sources primarily contaminated in water and sediment. Therefore, this study recommends regular monitoring PTE contaminations in the area to avoid any health hazards in the future.

Spatio-temporal Sediment Quality Risk Assessment by Using Ecological and Statistical Indicators: A Review of the Upper Sakarya River, Türkiye.

In this study, heavy metal accumulation levels (Cu, Zn, Cr, Pb, As) in biotic [Carassius gibelio (Bloch, 1782), Squalius pursakensis (Hankó 1925)] and abiotic (sediments) components in a significant freshwater ecosystem in Türkiye were investigated on the basis of seasonal variations using geographic information systems (GIS) and some ecotoxicological risk assessment indices [PLI (pollution load index), PERI (potential ecological risk index), Igeo (geo accumulation index), CF (contamination factor) and BRI (Biological Risk Index)]. GIS-based maps were utilized to depict the distribution of ecotoxicological risk assessment indices to provide a visual explanation by using the Inverse Distance Weighted (IDW) as an estimation method. Samples were collected seasonally from 12 stations selected on the Upper Sakarya River Basin, which is one of the longest fluvial ecosystems in Türkiye. As a result of applied indices, cadmium was found as the most hazardous heavy metal in terms of PERI and CF, nickel was found as the most hazardous heavy metal in terms of BRI and arsenic was found as the most hazardous heavy metal in terms of Igeo. As a result of applied PCI, 2 statistically significant factors explained 81.31% of the total variance. It was also determined that levels of almost all the investigated heavy metals (except Zn) in muscle tissues of fishes were under the permissible limits of Turkish legislation and the FAO.

Ecotoxicological evaluation of organic contamination in the world's two significant gateways to the Black Sea using GIS techniques: Turkish Straits.

This study was carried out to determine the spatial-temporal distributions of limnological parameters of Çanakkale Strait (ÇS) and Istanbul Strait (IS), Turkiye. Fluvial (n = 11) and lacustrine (n = 4) habitats water samples were collected in the dry and rainy seasons of 2022-2023. Among limnological parameters, the highest mean electrical conductivity values of 6063 µS/cm were noted in the IS basin during the rainy season and the lowest was 0.04 mg/L for nitrite in the ÇS basin. Generally, the levels of organic contaminants and ecological risk indices were as follows: rivers of IS > rivers of ÇS > Alibey Dam Lake (IS) > Atikhisar Dam Lake (ÇS). The highest non-carcinogenic health risks of 0.88 were noted for children in the ÇS basin during the dry season and the lowest of <0.01 in Atikhisar Dam Lake during the rainy season. Multivariate statistical techniques were applied to data to categorize investigated ecosystems and sources apportionment of contaminants and geospatial distribution.

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.

Spatial-temporal distributions, probable health risks, and source identification of organic pollutants in surface waters of an extremely hypoxic river basin in Türkiye.

This study was carried out to determine the spatiotemporal distributions of organic pollution parameters in the Meriç-Ergene River Basin subjected to intensive agricultural and industrial pressure. A total of 5 basin components, including Anadere (A), Çorlu (Ç), Tunca (T), Meriç (M), and Ergene (E) rivers, and 9 stations (A1, Ç1, T1, M1-M2, and E1-E4) were identified in the watershed, and surface water samples were collected in the dry (end of summer) and wet (end of winter) seasons of 2021-2022. The Water Quality Index (WQI) and Nutrient Pollution Index (NPI) were applied to the data to evaluate the overall water quality characteristics. The Chronic Daily Index (CDI), Hazard Quotient (HQ), and Hazard Index (HI) were applied to the data to reveal the probable noncarcinogenic health risks of organic contaminants. Cluster Analysis (CA) and Principal Component Analysis (PCA) were applied to the data to classify the sampling sites and identify the source apportionment of organic pollution parameters. The recorded spatiotemporal averages of the investigated parameters in the basin are as follows: 6.26 mg/L for DO, 9 for pH, 1626 µS/cm for EC, 985 mg/L for TDS, 1 ‰ for salinity, 6.88 mg/L for nitrate, 0.1 mg/L for nitrite, 1.8 mg/L for phosphate, 81 mg/L for sulfate, and 473 mg/L for chloride. The results indicate that the most contaminated components of the basin are Çorlu Stream and Ergene River, and in addition to their quite high salt and nutrient content, they have extreme hypoxic conditions to the extent that it is impossible for many aquatic organisms to live. The contamination degrees of the investigated basin components were determined using the organic pollution risk assessment indices as follows: Çorlu Stream > Ergene River > Anadere Stream > Tunca River > Meriç River.

Identifying factors affecting irrigation metrics in the Haor basin using integrated Shannon's entropy, fuzzy logic and automatic linear model.

The sustainability of agricultural practices is seriously threatened by the quality of water used for irrigation. This paper aims to evaluate the suitability of irrigation water and identify the region suitable for agricultural use in the Haor basin of Bangladesh using conventional irrigation indices such as sodium adsorption ratio (SAR), percent sodium (Na%), magnesium hazard ratio (MHR), permeability index (PI), and Kelly's ratio (KR), as well as novel irrigation indices such as, Shannon's entropy index for irrigation water quality (EWQ) and fuzzy logic index for irrigation water quality (FIWQI). The main influences of groundwater and surface water parameters on irrigation indices were predicted using automatic linear modeling (ALM). Forty water samples were collected from shallow tube wells, rivers, canals, ponds, and drainage systems within agricultural land sampled and analyzed for cations and anions. SAR and KR show that 52.5% and 60% of the samples exceeded the allowable level, respectively, indicating that they were unsuitable for irrigation. According to EWQI, about 55% of the analyzed samples were of good quality, while 45% were of medium quality. ALM predicted that KR (0.98), Na% (0.87), and MHR (0.14) were the main significant factors affecting SAR and KR. ALM shows that elevated sodium, magnesium, and calcium are the most important factors affecting irrigation water suitability. The EWQI and FIWQI integrated models showed that water from nearly 30% of the sampling sites would need treatment before use. A new suitability map created by overlaying all parameters showed that surface water and some groundwater in the western and southwestern portions are suitable for agriculture. The north-central part is unsuitable for irrigation due to excessive sodium and magnesium levels. This paper will highlight the irrigation pattern for regional water resource use, identify new suitable regions, and improve sustainable agricultural practices in the Haor basin.

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.

Effects of COVID-19 era on a subtropical river basin in Bangladesh: Heavy metal(loid)s distribution, sources and probable human health risks.

The COVID-19 era has profoundly affected everyday human life, the environment, and freshwater ecosystems worldwide. Despite the numerous influences, a strict COVID-19 lockdown might improve the surface water quality and thus provide an unprecedented opportunity to restore the degraded freshwater resource. Therefore, we intend to investigate the spatiotemporal water quality, sources, and preliminary health risks of heavy metal(loid)s in the Karatoya River basin (KRB), a tropical urban river in Bangladesh. Seventy water samples were collected from 35 stations in KRB in 2019 and 2022 during the dry season. The results showed that the concentrations of Ni, Cu, Zn, Pb, Cd, and Cr were significantly reduced by 89.3-99.7 % during the post-lockdown period (p < 0.05). However, pH, Fe, Mn, and As concentrations increased due to the rise of urban waste and the usage of disinfectants during the post-lockdown phase. In the post-lockdown phase, the heavy metal pollution index, heavy metal evaluation index, and Nemerow's pollution index values lessened by 8.58 %, 42.86 %, and 22.86 %, respectively. Besides, the irrigation water quality indices also improved by 59 %-62 %. The total hazard index values increased by 24 % (children) and 22 % (adults) due to the rise in Mn and As concentrations during the lockdown. In comparison, total carcinogenic risk values were reduced by 54 % (children) and 53 % (adults) in the post-lockdown. We found no significant changes in river flow, rainfall, or land cover near the river from the pre to post-lockdown phase. The results of semivariogram models have demonstrated that most attributes have weak spatial dependence, indicating restricted industrial and agricultural effluents during the lockdown, significantly improving river water quality. Our study confirms that the lockdown provides a unique opportunity for the remarkable improvement of degraded freshwater resources. Long-term management policies and regular monitoring should reduce river pollution and clean surface water.

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.

Comparisons of diatoms and fishes as toxic metal bioindicator: a case study of an A-class wetland in northwest Turkey under effect of an intensive paddy cultivation stress.

In this research, diatoms as the first step and fishes as the last step of the food chain were compared as toxic metal accumulation bioindicator in an A-class wetland in Turkey. Bioaccumulations of potentially toxic elements (PTEs) were determined in liver, gill and muscle tissues of two commercially consumed fish species Carassius gibelio and Cyprinus carpio and in frustules of epiphytic diatom communities living on submerged macrophytes. Samples were collected seasonally from the Gala Lake, which is among the best stopover habitats of birds migrating between Europe and Africa, considering the paddy harvest period that is a major stress factor for the ecosystem. Also, potential human health risks associated with the consumption of fishes and consumption - dermal contact of diatoms were evaluated both for summer - before paddy harvest (BPH) and autumn - after paddy harvest (APH) periods. As a result of this research, the investigated toxic metal concentrations were increased significantly in diatoms in the APH period, while less significant exchanges were recorded in fishes. The bioaccumulations of PTEs were ranked as follows: Zn > Mn > Se > Cu > B > Cr > Ni > As > Pb > Cd for C. gibelio; Zn > Mn > Se > Cu > B > Cr > As > Ni > Pb > Cd for C. carpio; and Mn > Zn > Se > Pb > B > Ni > Cr > Cu > As > Cd for diatom frustules. Although the HI values in diatoms detected in the APH period were statistically significantly higher (about 1000 times; p < 0.05) than detected in the BPH period, they were less than the limit of 1 in both seasons. However, the HI coefficients of fishes were quite higher than the limit (an average of 23.59 for C. gibelio and 19.18 for C. carpio), which means quite high probable non-carcinogenic health risks for humans. Furthermore, the CR coefficients of Cr, Ni and As in muscle tissues of fishes were considerably higher than the limit of 10-4, which reflects a significant carcinogenic health risk for consumers. The data showed that although the fishes at the top of the food chain bioaccumulate the PTEs in their tissues much higher than the diatoms at the bottom of the food chain, the diatoms are much more sensitive to changes in the environmental conditions than the fishes and they are more effective biological tools as toxic metal accumulation bioindicators.

Assessment of the effects of COVID-19 lockdown period on groundwater quality of a significant rice land in an urban area of Türkiye.

In the current research, the impact of the COVID-19 lockdown period on groundwater quality of Lower Meriç Plain (Thrace Region of Türkiye) was evaluated. Some significant nutrient characteristics (NO3-, NO2-, and PO43-), salinity characteristics (EC, TDS, and salinity), and physical characteristics (temperature, DO, pH, and turbidity) were investigated in groundwater samples collected from 45 sampling points in pre-lockdown and lockdown periods. Water quality index (WQI) and nutrient pollution index (NPI), Pearson correlation index (PCI), cluster analysis (CA), one-way ANOVA test (OWAT), and factor analysis (FA) were applied to assess ecological risk. Excluding recorded statistical differences in temperature and DO due to climatic conditions (p < 0.05), levels of all the investigated water quality parameters show no statistically significant differences and no significant reduction in pollutants measured in the lockdown period. On the contrary, the WQI and NPI scores have increased between the rates of 4.76-27.10% during the lockdown period. In the lockdown period, although the reduction of industry or limited production of many industrial facilities reduced the inorganic contaminant releases to the environment, ongoing agricultural activities and domestic wastes caused to prevent the reduction of organic pollutants in groundwater of the region during the lockdown period.

Ecotoxicological risk assessment for sediments of Çavuslu stream in Giresun, Turkey: association between garbage disposal facility and metallic accumulation.

The objective of this paper was to stress the possible potential toxic element (PTE) accumulation in the surface sediments of the Çavuslu Stream (ÇS), as well as examining the source identification of whether or not any association between garbage disposal facility (GDF) and ecotoxicity or human health risk in Giresun, Turkey. The sediment specimens were analyzed by inductively coupled plasma mass spectroscopy (ICP-MS) followed by microwave digestion. The descending order of metals (mg/kg) in sediments were as follows: Fe (38,791 ± 3269) > Al (27,753 ± 4051) > Mn (730.90 ± 114.60) > Cr (233.39 ± 53.32) > V (176.40 ± 19.66) > Cu (85.22 ± 6.06) > Ni (72.87 ± 11.50) > Zn (46.45 ± 3.68) > Co (21.96 ± 3.33) > Pb (12.17 ± 1.97) > As (3.12 ± 1.45) > Sb (0.22 ± 0.06) > Cd (0.17 ± 0.02) > Hg (0.04 ± 0.01). Among these elements, certain metals (V, Cr, Cu, and Ni) in the sediments were above the average shale. Cr and Ni levels were above their corresponding threshold effect level (TEL) and probable effect level (PEL) values while Cu concentration exceeding its TEL, indicating that benthic organisms in the sediment of ÇS have likely toxic responses. Based on the results from contamination factor (CF), enrichment factor (EF), and geo-accumulation factor (Igeo) values of PTEs, the sediment was frequently classified into moderate contamination, moderate enrichment, and unpolluted to moderately polluted group. Pollution load index (PLI), integrated pollution index (IPI), and ecological risk index (Eri) indicated low pollution or low potential ecological risk. Toxicity risk index (TRI) and toxic unit analysis (TUs) suggested moderate toxicity. The outcomes of hazard quotient (HQ), total hazard index (THI), and lifetime cancer risk (LCR) stressed out that PTEs would not pose a significant health risk when adults are exposed to sediments in ÇS. However, a non-cancerogenic health risk for children was considered as the collective effect of 14 PTE (THI = 1.47 > 1). Multivariate statistical analysis (principal component analysis (PCA), Pearson's correlation coefficient (PCC), and hierarchical cluster analysis (HCA)) outlined that the metallic accumulation in the sediments of ÇS was related to lithological, geological, and anthropogenic impacts. Therefore, the GDF is likely a major reason in terms of anthropogenic pollution in the sediments of the ÇS.

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.

Ecological risks and controlling factors of trace elements in sediments of dam lakes in the Black Sea Region (Turkey).

The evaluation of trace elements (TEs) in sediments of dam lakes is crucial for maintaining ecosystem health. Therefore, it is very important to determine their concentrations, pollution status, sources, controlling factors and ecological risks in these ecosystems. Here, for the first time, we analyzed 14 TEs (Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Cd, Sb, Hg and Pb) and sediment properties (organic matter (OM) and pH) in sediments from four dam lakes (Erfelek, Derbent, Suat Ugurlu and Saraydüzü) in the Black Sea Region of Turkey, which are used for different purposes and located on the different rivers or streams with different pollution levels. The results indicated that Al, V, Mn, Fe, Cu, Zn, As, Pb and Sb concentrations were lower in the Erfelek Dam Lake which has been used for drinking water supply, indicating that it is more protected than other dam lakes. However, Al, V, Mn, Fe, Co, Cu and Sb concentrations were higher in the Suat Ugurlu Dam Lake on the Yesilirmak River which is moderately polluted. According to sediment contamination indices, there was low contamination in the sediments of all dam lakes. Similarly, the assessment of ecological risk posed by TEs indicated low eclogical risk in the dam lakes. Sediment OM and pH were found to be important control factors affecting the distribution of TEs in the dam lakes sediments. Correlation and factor analyses suggested that all TEs in the sediments of dam lakes mainly originated from geogenic sources.

Variations, health risks, pollution status and possible sources of dissolved toxic metal(loid)s in stagnant water bodies located in an intensive agricultural region of Turkey.

There are many reservoirs, ponds and lakes in the Meriç-Ergene River Basin (Turkey), which is an intensive agricultural region. Since agrochemicals are extensively applied to the agricultural soils in the basin, these water bodies may be contaminated with toxic metal (loid)s (TMs). However, no study has been conducted to determine TM levels in the water bodies. In this study, levels of seven TMs (Cr, As, Cu, N, Zn, Cd and Pb) in surface water samples taken from 25 different stagnant water bodies (11 reservoirs, 12 ponds and 2 lakes) in the dry and wet seasons were measured and compared with water quality guidelines. In addition, spatial and seasonal variations, health risks, pollution status and possible sources of TMs were assessed. The mean As concentration of the lakes was significantly higher due to drainage water from paddy fields. The ponds had higher total mean TM concentration likely due to their low water volume. Surface runoff from rainfall caused the Cr, Zn, Cd, Pb and Cu concentrations to increase in the wet season. Only the mean As concentration of the lakes in the dry season was above the drinking water standards. Metal pollution indices showed low contamination of the water bodies in both seasons. Health risk indices indicated that As in the lakes in the dry season via ingestion exposure pathway may pose both non-carcinogenic and carcinogenic health risks to the residents. The results of factor and correlation analyses showed that among the studied TMs, only As originated from anthropogenic sources. The findings of this study revealed that agricultural activities caused As pollution in the lakes, while the reservoirs and ponds were not significantly affected by agricultural activities. We suggest that the levels of TMs in all water bodies should be measured at regular intervals to check the quality of surface water.