Environmental, ecological and human health risk assessment of heavy metals in sediments at Samsun-Tekkeköy, North of Turkey.

A detailed study was conducted in order to evaluate the effects of heavy metal pollution in the sediments in terms of environmental, ecological, and human health. Sediment samples were collected from 5 different points in two seasons, namely summer (August 2017) and winter (December 2017), to determine the distribution of heavy metals, potential pollutants, and toxic and ecological risks in the river sediments in Samsun-Tekkeköy district located in the Mid-Black Sea Region of Turkey and to evaluate the human health risk. The distribution of heavy metals at the sampling points was Fe>Al>Mn>Zn>Cu>Cr>Ni>Pb>Cd based on their averages. According to the toxic risk index (TRI) results, sampling point OIZ (Organized Industrial Zone) Channel (T3) was also found to have a moderate risk, and it was determined that the highest contribution was from Cu>Ni>Cd>Cr, respectively. Potential ecological risk index (PERI) results revealed a low risk except for Cd metal at all sampling points. While the sediment enrichment factor (EF) did not show much metallization at many points, the highest enrichment was observed in Cd, Cu, and Zn metals at sampling point T3. According to the geoaccumulation index (Igeo) and contamination factor (CF), sampling point T3 showed contamination with Cd, Cu, Cr, and Zn. Evaluation of human health risk showed that the hazard index (HI) results of carcinogenic and non-carcinogenic risks were higher among children than adults. The total lifetime cancer risks (TLCR) of heavy metals were within the limits determined by USEPA. However, the risk was ranked as Cr>Cd>Pb. Sediment quality guidelines (SQGs) and pollution index results showed that heavy metal contamination was due to anthropogenic and industrial activities since the region was an industrial zone. It was determined that heavy metals posed ecological risks and that the Samsun-Tekkeköy region was moderately and significantly contaminated.

Distribution and bioaccumulation of organochlorine pesticides along the Black Sea coast.

Sediment, mussel, and seawater samples were collected three times during 2001-2003 at nine sampling stations along the mid-Black Sea coast of Turkey. The samples were analyzed with GC-ECD for contents of various organochlorine pesticides (OCPs) in the environment. DDT and its metabolites were detected at concentrations significantly above the detection limits. The highest concentrations of DDT metabolites measured in the sediment and mussel samples were 35.9 and 14.0 ng/g wet weight respectively. Considerable levels of aldrin, dieldrin, endrin, heptachlor epoxide, lindane, endosulfan sulphate, and HCB were also detected in the sediment, mussel, or seawater samples. Although these persistent toxic compounds have been banned for some years in Turkey, they may still be used illegally in some regions, contributing to their significant levels in the environment. The biota-sediment accumulation factor (BSAF) estimated for DDT and its metabolites in mussels was 2.9, which is nearly two times higher than the benchmark of 1.7. In spite of such high BSAF values observed for these toxic compounds, their levels in mussels were significantly below the international legal limits recommended by the Food and Agriculture Organization of the United Nations. Edible biota from the waterbodies examined may thus still be considered safe for human consumption at this time. However, as pollutants can biomagnify through the food chain over time, further routine sampling and analysis of biota along the Black Sea coast are warranted in order to better assess the threat of OCPs to public health in the region.

A survey to determine levels of chlorinated pesticides and PCBs in mussels and seawater from the Mid-Black Sea Coast of Turkey.

A mussel and seawater monitoring survey was conducted at six sampling points between Yalikoy (Ordu) and Sinop in 1999-2000 along the Mid-Black Sea Coast of Turkey in order to assess concentrations of organochlorine pesticides (OCs) and polychlorinated biphenyls (PCBs). Chlorinated pesticides and PCBs were measured in the mussel Mytilus Galloprovincialis and in seawater. In the mussel samples, the most common pollutants in terms of average concentration per g of wet weight (ww), were DDT (max. 1800 pg/gww, min. 240 pg/gww) and its metabolites DDD (max. 5400 pg/gww, min. 240 pg/gww) and DDE (max. 2800 pg/gww, min. 70 pg/gww). Also, dieldrin, heptachlor and HCB were notable contaminants in the mussel samples. PCBs were determined in none of the biota or seawater samples. The concentrations of the OCs and PCBs in mussels were higher in coastal areas receiving river discharges and close to the largest city of the region, Samsun (especially in sampling points in the harbour area). The well-known long persistence of DDTs and other chlorinated compounds was confirmed by residues of these pollutants measured in mussels. On the other hand, even though the usage of such kind of persistent compounds in Turkey was banned, there may still be illegal usage and it is not certain whether the application of these compounds did end in the region.