Memet Varol

Assessment of heavy metal contamination in sediments of the Tigris River (Turkey) using pollution indices and multivariate statistical techniques

Heavy metal concentrations in sediment samples from the Tigris River were determined to evaluate the level of contamination. The highest concentrations of metals were found at the first site due to metallic wastewater discharges from copper mine plant. Sediment pollution assessment was carried out using contamination factor (CF), pollution load index (PLI), geoaccumulation index (Igeo) and enrichment factor (EF). The CF values for Co, Cu and Zn were >6 in sediments of the first site, which denotes a very high contamination by these metals. The PLIs indicated that all sites except the first site were moderately polluted. Cu, Co, Zn and Pb had the highest Igeo values, respectively. The mean EF values for all metals studied except Cr and Mn were >1.5 in the sediments of the Tigris River, suggesting anthropogenic impact on the metal levels in the river. The concentrations of Cr, Cu, Ni and Pb are likely to result in harmful effects on sediment-dwelling organisms which are expected to occur frequently based on the comparison with sediment quality guidelines. PCA/FA and cluster analysis suggest that As, Cd, Co, Cr, Cu, Mn, Ni and Zn are derived from the anthropogenic sources, particularly metallic discharges of the copper mine plant.

Assessment of surface water quality using multivariate statistical techniques: a case study of Behrimaz Stream, Turkey

Multivariate statistical techniques, such as cluster analysis (CA), principal component analysis, and factor analysis, were applied for the evaluation of temporal/spatial variations and for the interpretation of a water quality data set of the Behrimaz Stream, obtained during 1xa0year of monitoring of 20 parameters at four different sites. Hierarchical CA grouped 12xa0months into two periods (the first and second periods) and classified four monitoring sites into two groups (group A and group B), i.e., relatively less polluted (LP) and medium polluted (MP) sites, based on similarities of water quality characteristics. Factor analysis/principal component analysis, applied to the data sets of the two different groups obtained from cluster analysis, resulted in five latent factors amounting to 88.32% and 88.93% of the total variance in water quality data sets of LP and MP areas, respectively. Varifactors obtained from factor analysis indicate that the parameters responsible for water quality variations are mainly related to discharge, temperature, and soluble minerals (natural) and nutrients (nonpoint sources: agricultural activities) in relatively less polluted areas; and organic pollution (point source: domestic wastewater) and nutrients (nonpoint sources: agricultural activities and surface runoff from villages) in medium polluted areas in the basin. Thus, this study illustrates the utility of multivariate statistical techniques for analysis and interpretation of data sets and, in water quality assessment, identification of pollution sources/factors and understanding temporal/spatial variations in water quality for effective stream water quality management.

Dissolved heavy metal concentrations of the Kralkızı, Dicle and Batman dam reservoirs in the Tigris River basin, Turkey.

Water samples were collected at monthly intervals during 1 year of monitoring from Kralkızı, Dicle and Batman dam reservoirs in the Tigris River basin to assess the concentrations of dissolved heavy metals and to determine their spatial and seasonal variations. The results indicated that dissolved heavy metal concentrations in the reservoirs were very low, reflecting the natural background levels. The lowest total metal concentrations in the three dam reservoirs were detected at sampling sites close to the dam wall. However, the highest total concentrations were observed at sites, which are located at the entrance of the streams to the reservoirs. Fe, Cr and Ni were the most abundant elements in the reservoirs, whereas Cd and As were the less abundant. The mean concentrations of dissolved metals in the dam reservoirs never exceeded the maximum permitted concentrations established by EC (European Community), WHO and USEPA drinking water quality guidelines. All heavy metals showed significant seasonal variations. As, Cd, Cr, Cu, Fe, Ni and Pb displayed higher values in the dry season, while higher values for Zn in the wet season. Cluster analysis grouped all ten sampling sites into three clusters. Clusters 1 and 2, and cluster 3 corresponded to relatively low polluted and moderate polluted regions, respectively. PCA/FA demonstrated the dissolved metals in the dam reservoirs controlled by natural sources.

Dissolved heavy metals in the Tigris River (Turkey): spatial and temporal variations

Multivariate statistical techniques, such as analysis of variance, cluster analysis (CA), correlation analysis, principal component analysis (PCA), and factor analysis (FA), were applied to determine the spatial and temporal variations of dissolved heavy metals in the Tigris River at 7 different sites spread over the river stretch of about 500xa0km during the period of February 2008 to January 2009. The results indicated that Fe, Cr, and Ni were the most abundant elements in the river water, whereas Cd and As were the less abundant. Cu, Fe, Ni, and Zn showed significant spatial variations, reflecting the influence of anthropogenic activities. The lowest total concentration of heavy metals was found at site 2 downstream of the Dicle Dam due to clean water from the dam. The concentrations of most metals were found lower when compared with results of previous studies due to reduction of the activity of the copper mine plant and the construction of two dams on the river. The lowest total concentrations were determined in February due to high precipitation and snow melts. Hierarchical agglomerative CA classified all the sampling sites into three main groups of spatial similarities. Clusters 1 (Maden and Bismil), 2 (Cizre), and 3 (Eğil, Diyarbakır, Batman, and Hasankeyf) corresponded to moderate polluted and relatively low polluted regions, respectively. PCA/FA, CA, and correlation analysis suggest that Cu, Ni, and Zn are controlled by anthropogenic sources.

Organochlorine pesticide, antibiotic and heavy metal residues in mussel, crayfish and fish species from a reservoir on the Euphrates River, Turkey

This study investigated the residues of 19 organochlorine pesticides, 37 antibiotics and 5 heavy metals in biota samples (one mussel species, one crayfish species, six wild fish species and one farmed fish species) from the Keban Dam Reservoir on the Euphrates River, Turkey. Among monitored OCPs, only p,p-DDE was detected in biota samples. It was found only in mussel, fish muscle and fish gill samples. The highest concentration of p,p-DDE (0.032xa0mg/kg ww) was determined in the gill of common carp, which was found to be below the maximum residue limit (MRL). Only sulfadimethoxine was detected among antibiotics in biota samples. Its maximum concentration (0.0044xa0mg/kg ww) did not exceed the MRL of 0.1xa0mg/kg. Sulfadimethoxine was found only in muscle and gill of common carp collected from site S6, where there are many rainbow trout cage farms. However, no detectable residue of sulfadimethoxine was found in farmed rainbow trout. The highest concentrations of As, Cd and Pb were detected in mussels, while the highest concentrations Cu and Zn were determined in crayfish. Metal concentrations in biota samples did not exceed the maximum permissible levels. According to these results, the consumption of biota samples from the Keban Dam Reservoir is safe for human health.

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.

Heavy metal and arsenic concentrations in rainbow trout (Oncorhynchus mykiss) farmed in a dam reservoir on the Firat (Euphrates) River: Risk-based consumption advisories

The concentrations of ten metals in rainbow trout (Oncorhynchus mykiss) farmed in the Karakaya Dam Reservoir (Turkey) on the Firat River were determined. The metal concentrations in rainbow trout did not exceed the maximum permissible levels. Biomagnification factors (BMF) of ten metals were <1, indicating that these metals were not biomagnified. The estimated daily intake (EDI) of each metal was much lower than the respective tolerable daily intake (TDI). The target hazard quotient (THQ) for individual metal and total THQ for combined metals were lower than 1, indicating no health risk for consumers due to the intake of either individual metal or combined metals. The cancer risk (CR) value for toxic inorganic As was below 10-6, indicating no carcinogenic risk. According to the calculated maximum allowable consumption rates (CRmm), an adult may safely consume 28 meals of rainbow trout from the dam reservoir per month with no adverse carcinogenic and non-carcinogenic health effects. According to these results, the consumption of rainbow trout farmed in this dam reservoir is completely safe for human health.

Biomonitoring of Trace Metals in the Keban Dam Reservoir (Turkey) Using Mussels (Unio elongatulus eucirrus) and Crayfish (Astacus leptodactylus)

Freshwater mussels and crayfish are commonly used as biomonitors of trace metals. In the present study, the concentrations of ten metals were determined in mussels (Unio elongatulus eucirrus) and crayfish (Astacus leptodactylus) collected from the Keban Dam Reservoir in Turkey. The significant spatial differences in concentrations of studied metals except As in mussels were not found. However, Co, Cr, Cu, and Zn concentrations in mussels and As, Co, Cu, Fe, Pb, and Zn concentrations in crayfish showed significant seasonal differences. As, Cd, and Mn levels in mussels were about nine times higher than those in crayfish. The concentrations of Cd, Cr, Cu, Pb, Zn, and inorganic As in crayfish and mussels were lower than maximum permissible levels. When compared with other biomonitoring studies using mussels and crayfish, high concentrations of As, Cd, Co, Cr, and Ni in mussels and Cr and Ni in crayfish were observed due to lithogenic sources and anthropogenic activities in the basin. Bioconcentration factor values of Fe, Mn, Cd, and Zn in mussels and Zn, Cu, Fe, and Co in crayfish were >u20091000, which indicates that both U. e. eucirrus and A. leptodactylus have potential to bioaccumulate these metals. Therefore, attention should be paid to mussels and crayfish from ecological and human health perspective, because they are potential vectors of metals to higher trophic levels.

Thirty-four new records and the diversity of the Rotifera in the Turkish part of the Tigris River watershed, with remarks on biogeographically interesting taxa

A total of 175 morphospecies belonging to 47 genera of the monogonont Rotifera are reported here, representing the highest rotifer biodiversity recorded from any body of water in Turkey; 34 of these species are new records for the Turkish fauna. The genera Donneria De Smet, Octotrocha Thorpe and Stephanoceros Ehrenberg are recorded for the first time in Turkey. The eastern Oriental taxon Brachionus murphyi Sudzuki and the tropicopolitan Trichocerca braziliensis (Murray) are new records for both the Palearctic region and western Asia. Additionally, the Palearctic European species Cephalodella cf. ungulata Fischer and Ahlrichs and Lecane margalefi De Manuel are recorded for the first time in Asia and for the second time outside of their type localities. The Tigris River is the third locality reported for the distribution of Donneria sudzukii (Donner). All observed species were members of 23 families with the majority (72%) of the examined fauna belonging to the following families: Notommatidae (33 species) > Lecanidae (30 species) > Brachionidae (25 species) > Dicranophoridae (14 species) > Lepadellidae (13 species) > Trichocercidae (11 species). Littoral rotifers made a significant contribution to the overall species diversity observed. Due to the strategic geographic position of Turkey, it is important to conduct species inventories in different localities of the country to fill distributional gaps for many rotifer species. The rotiferan species richness found in the study region and the biogeographically interesting elements of this river are remarkable and are discussed here. Additionally, this report represents the most up-to-date review of Turkish rotifers.

Trace Metal Levels in Rainbow Trout ( Oncorhynchus mykiss ) Cultured in Net Cages in a Reservoir and Evaluation of Human Health Risks from Consumption

Although fish consumption has positive health effects, metals accumulated in fish can cause human health risks. In this study, the levels of ten metals in rainbow trout (Oncorhynchus mykiss) farmed in the Keban Dam Reservoir, which has the biggest rainbow trout production capacity in Turkey, were determined and compared with the maximum permissible levels (MPLs). Also, human health risks associated with rainbow trout consumption were assessed. The metal concentrations in rainbow trout were found below the MPLs. The estimated daily intake of each metal was much lower than the respective tolerable daily intake. The target hazard quotient (THQ) for individual metal and total THQ for combined metals did not exceed 1, indicating no health risk for consumers. The cancer risk (CR) value for inorganic arsenic was within the acceptable lifetime risk range of 10−6 and 10−4. For carcinogenic and non-carcinogenic effects, the maximum allowable fish consumption rates were high enough to ensure the human health. According to these results, the consumption of rainbow trout farmed in the Keban Dam Reservoir does not pose a risk on human health.