Assessment of As, Cd, Ni and Cr Contamination in Water, Sediments and Fish of Shahid Rajaie Dam, North Iran

The pollution of the aquatic environment with heavy metals and trace elements has become a worldwide problem during recent years, because they are indestructible and most of them have toxic effects on organisms. Potentially toxic elements (PTEs) added to an aquatic system by anthropogenic and natural sources are distributed during their transport between different compartments of aquatic ecosystems, such as water, sediment and biota. The main goals of present study are: 1) determine concentrations of As, Cd, Ni and Cr in water and sediment as well as their accumulation in fish, 2) Evaluating contamination and toxicological factor in the river and lake dam sediments and 3) calculate monthly fish consumption limits for carcinogenic and noncarcinogenic health. Study area Shahid Rajaei dam is located in 40Km south of the Sari City, in the north part of Iran (Fig. 1) with 160 million cubic meters capacity and approximate catchment of 1244Km2. It is constructed on Tajan River and its reservior is fed by Shirinrood and Sefidrood rivers (in the confluence of these rivers, Tajan river arise). It was designed to provide irrigation, drinking, and industrial water in the region. The main activities in this area are agriculture, crop irrigation, and dairy activities. The main human settlements are in upstream including Ferim, Afrachal, Ali-Abad, Sekuya villages with a total of more than 10000 habitants. Geological formations in the region in terms of lithology are mainly limestone, dolomitic limestone, sandstone, marl and shale (Fig. 1). Sampling and analysis For water quality assessment, 16 water samples were collected from the surface waters including 9 sites along the Shirinrood (Sh-1 to Sh-9) and 4 sites along Sefidrood (S-1 to S-4) rivers and 3 samples from Lake Dam (M-1 to M-3) during two periods (November 2012 and September 2013). The location of the sampling points is shown in Fig. 1. The samples were kept at 4°C prior to analysis. As, Cd, Ni and Cr were analyzed by ICP-MS in Westlab, Australia. 26 Sediment samples were collected from Sefidrood, Shirinrood rivers and dam lake, using a pre-cleaned stainless steel grab sampler for Lake samples (SR-7 to SR-15) and using a plastic scoop for river samples (SR-1 to SR-6 and SR-16 to SR-26) in October 2012. Figure 2 shows the location of the sampling points. The collected samples were immediately stored in polyethylene bags and air-dried in the laboratory at room temperature. Then, gravel and plant root were removed. The samples were passed through a 63 micron steel sieve. The concentrations of the constituent potentially toxic elements (PTEs) were measured at Zar Azma Laboratory (Iran) using ICP-MS methods. Fish samples, including two species Barbel and L. cephalus of Cyprinidae family, were collected from the Lake Dam. The fish samples were washed with deionized water, packed in polyethylene bags and kept at -20°C, then, transported on ice to the laboratory. As, Cd, Cr and Ni were analyzed by atomic absorption spectrometry.