Comprehensive natural radioactivity and pollution risk assessments of aquatic media and sediment in Lake Van (Türkiye).

This paper studies the radionuclide (137Cs, 226Ra, 232Th, 40K) activity concentrations and gross radioactivities in waters and sediments of Lake Van, which is the third largest closed lake (with no natural or artificial outlet) within the Earth. The physico-chemical parameters were measured and evaluated in the lake waters. The mean gross α activities in surface, middle and bottom waters are 0.04, 0.03 and 0.03 Bq/L, respectively, and in the same order, the mean gross ß activities are 0.30, 0.23 and 0.33 Bq/L, respectively. In sediment samples, the mean activity concentrations were measured as 1.98 Bq/g for gross-α, 3.46 Bq/g for gross-ß, 48.3 Bq/kg for 226Ra, 32.0 Bq/kg for 232Th, 540.1 Bq/kg for 40K and 25.9 Bq/kg for 137Cs. The radiation hazard parameters values based on the measured activities were calculated and Raeq values are lower than the world average value in all samples, while Dout and AED values are relatively high in some sediment samples.

The first evidence of microplastic uptake in natural freshwater mussel, Unio stevenianus from Karasu River, Turkey.

PURPOSE: Microplastic pollution is a major problem that threatens freshwater mussels as well as marine bivalves, since these filter-feeding organisms are directly exposed to microplastics in the water column. There is no study on the microplastic contamination of Unio stevenianus as a bioindicator organism. The aim of this study is to determine the microplastic contamination in U. stevenianus. MATERIALS AND METHODS: In total, 32 U. stevenianus were obtained from three different sites from Karasu River, in October 2020. The soft tissue of each mussel was digested and filtered. The filters with microplastics were observed under a stereomicroscope. RESULTS: A total of 1,253 microplastics, ranging from 0.81 to 6.69 items/gram (mean 2.85 ± 1.27 items/g) and 13.00 to 84.73 items/individual (mean 39.15 ± 16.95 items/individual), were extracted from soft tissues of mussel for all stations. The dominant of the detected microplastics consisted of fragment (48.8%) followed by fiber (47.5%) types, and ˂0.1 mm size (44.8%), irregular shape (48.7%) and black coloured (48.8%) items were the most uptaked microplastics. CONCLUSION: This study indicated that U. stevenianus has a lot of pollution where there are a lot of microplastics in the river.

High levels of microplastic ingestion by commercial, planktivorous Alburnus tarichi in Lake Van, Turkey.

Microplastic pollution of inland environments has been receiving increased publicity over the last few years. For the first time, this study reports on the presence of microplastics (0.1 mm to <5 mm) in the gastrointestinal tracts of Alburnus tarichi in Lake Van from January to April 2020. In total, 101 fishes were obtained from Citoren, Edremit, Gevas and Dagonu fisheries regions. A total of 3338 pieces of plastic, ranging from 8 to 124 samples per fish with averaging 34 ± 13 MPs/individual, were extracted from gastrointestinal tracts of fish. The majority of the ingested particles consisted of fibres (74%), and blue coloured material was the most consumed microplastic. The polymers identified by Fourier Transform Infrared Spectroscopy (FTIR) were polyethylene and polypropylene. Consequently, this study suggested that the vast majority of A. tarichi were contaminated with microplastics and showed higher abundance in comparison with other worldwide studies so far.