Iranian Journal of

Background and Objective: Heavy metals contamination, particularly in aquatic environments, is an important concern.  Since Mahbad river is the source for supplying drinking water to the city and the dam established on it is used for catching fish and sale in the market, heavy metals concentrations in the sediments of Mahabad River and the Dam, and the possible health risk of the fish consumption were investigated.
Materials and Methods: Sediment samples from 21 sites in Mahabad dam, and river, and 16 fish samples (Sander lucioperca and bramis brama species) were collected. After preparation, the samples were analyzed using ICP-MS method. For data analysis, enrichment factor (EF), potential ecological risk index (RI), health risk indices, principal component analysis (PCA) and Mann-Whitney test were used.
Results: The EF and RI values of the studied heavy metals in the sediments were low. The max concentrations of lead, zinc, copper, arsenic and manganese were 36, 162, 74, 22.8 and 3221 mg/kg, respectively. This was more obvious in the samples taken from the downstream of the dam. However, accumulation of the heavy metals in fish tissues resulted in high values for total hazard quotients (THQ), particularly for As (1.19); high hazard index (above 1); and high estimated daily intake (EDI) for copper (1.64) in the study area.
Conclusion: The results of this study revealed that the conditions for elements’ mobility and bioavailability was suitable in the river and Mahabad Dam. Therefore, assessing the mobility and bioavailability of the heavy metals in the sediments of the region, and measurement and continuous monitoring of the heavy metals concentrations in the water, sediment and fish of the study area are needed.

Background and Objective: Microplastics (MPs) pollution are considered as a major growing global environmental problem in the past few decades. Dams could be an important reservoir for microplastics accumulation, therefore, in this study the presence of microplastics in sediments of Taleqan Dam and its upstream river was investigated in order to: 1) determine the local status of microplastic pollution and 2) determine the abundance and characteristics of the identified microplastics.
Materials and Methods: Sediment sampling was performed at 15 stations in the upstream of the river and the dam reservoir. After the sample preparation, separation method based on density difference was used for separation of the microplastics from the sediment, and stereo microscope and SEM-EDX were used for counting microplastics and investigation of their characteristics.
Results: Based on the results, maximum of the counted microplastic particles were observed in Taleqan City area with 2050 particles/300 g and minimum number was observed in the dam reservoir with 478 particles/300 g of sediment. The dominant shape, color, and size of the counted particles were polyhedral, colorless (transparent), and 100-250 μm, respectively.
Conclusion: The results showed that the concentration of microplastics in the stations near the urban and rural areas were higher due to the entry of sewage and the release of municipal solid wastes. Also, their concentrations were high in the stations close to the dock area of the dam due to the greater traffic of the locals and tourists and dumping of wastes in the shoreline of the lake.