Ecotoxicological risk assessment and source identification of heavy metals in the surface sediments of comlekci stream, Giresun, Turkey

Heavy metal (HM) pollution of river sediments is one of the most important problems encountered in the aquatic environments. The purpose of this study was to determine potential HM contamination in the sediments of comlekci stream and to assess the environmental risks associated with this contamination. To achieve these objectives, sediment samples were collected seasonally at three different stations, dried at 103 degrees C for 24 h, sieved to < 63 mu m, and analyzed for HMs with inductively coupled plasma-mass spectrometry (ICP-MS). The average concentrations (mg/kg) in the sediments were as follows: Iron (Fe) 8597 +/- 1726 > manganese(Mn) 297.7 +/- 48.42 > zinc (Zn) 60.09 +/- 46.52 > copper (Cu) 35.26 +/- 23.33 > lead (Pb) 19.91 +/- 11.01 > chrome (Cr) 7.89 +/- 2.78 > nickel (Ni) 7.01 +/- 3.33 > cobalt (Co) 5.77 +/- 1.32 > cadmium (Cd) 0.11 +/- 0.17. To determine the origins and the relationships of HMs, statistical methods such as Pearson's correlation coefficient analysis, principal component analysis and hierarchical cluster analysis were used. In addition, potential ecological risks and toxicity to human health were determined by performing calculations of the geoaccumulation index (I-geo), enrichment factor (EF), hazard index (HI), hazard quotient (HQ) and lifetime cancer risk (LCR) and comparing data to sediment quality guidelines (SQGs). The average enrichment factors (EFs) of Fe, Ni and Cr were less than 1.5, which indicates that they come from natural sources, while the other metals were consistently higher (EF > 1.5), which implies an anthropogenic influence. According toI(geo) results, there is limited contamination of sediments by Cu, Pb and Zn. Average value of SQGs showed that there is no environmental risk for aquatic biota. Data of HI, HQ, and LCR indicate that HMs do not pose carcinogenic risks or non-carcinogenic hazards to human health.