This paper is the first to report on the role of a wastewater treatment plant (WWTP) in Sari, as a source of microplastics (MPs) in the Caspian Sea. Composite 270-liter/24-hour samples were taken the treated effluent of the WWTP in winter and spring, two seasons with different levels of human activity. The effluent contained 380±52.5 and 423±44.9 MPs/m3 in winter and spring, respectively, with the total numbers of MPs/m3 not differing between the two seasons. The dominant type of MPs in the effluent was microfibers with 237±68.7 and 328±33.4 per m3 in winter and spring, respectively. In both seasons, fiber sizes of

This paper presents concentrations and sources of Aliphatic and Aromatic Hydrocarbons in the sediments from Babolsar coastal area and the inlet of Babolrood River in the southern side of the Caspian Sea. The concentration of hydrocarbons in 13 sediment samples from the study area were measured by gas chromatography (GC). Total Petroleum Hydrocarbon (TPH) concentrations in sediment samples in the coastal area ranged from 115 to 201 μg/g. In the inlet samples, TPH concentrations were close to each other and ranged from 294 to 367 μg/g. The TPH results showed moderate level of oil pollution in the study area. Total Polycyclic Aromatic Hydrocarbons (ΣPAHs) concentrations in sediment samples inside the inlet ranged from 498 to 702 ng/g, indicating moderate level of pollution. Concentrations of ΣPAHs in sediment samples in the coastal area ranged from 341 to 1703 ng/g, indicating moderate to less than significant level of pollution. Developed indices for pollutant origins showed that hydrocarbons in all sediment samples collected in the study area had petrogenic origin. The results also showed the Babolrood River as the main source of oil pollution in the sediments in the study area.

Over the last few decades, Anzali wetland has been at risk of pollutants, especially from heavy metals. The present research analyzes some physical and chemical properties and heavy metals concentration in 27 points in nine stations of Anzali wetland. The samples of each station have been mixed, acidic digested, and analyzed by inductively coupled plasma mass spectrometry (ICP-MS). The mean concentrations of Fe, Mn, Pb, Zn, As, Cd, Cu, Hg, Ni, and Cr have been 50527.2, 1210, 23.3, 79.4, 8.8, 0.23, 32.1, 0.25, 31.6, and 31.5 mg/Kg, respectively. In addition, it can be seen that the concentrations of Cd (0.31 mg/Kg) and As (25.47 mg/Kg) in Hendekhale station, Hg (0.52 mg/Kg) in Pirbazar station, and Pb (52.69 mg/Kg) in Khazar villa station surpass world surface rock average. According to contamination factor (CF), in case of Mn and Pb, both Hendekhale, and Khazar Villa stations have been in considerable contamination level. The calculation of Pollution Load Index (PLI) shows that Hendkhaleh and Khazar Villa stations have had moderate pollution. The mCd index survey indicates that only in Hendekhale station, has heavy metals contamination been at a low degree level of contamination. According to PER index, mercury metal contamination in Hendekhale station faces medium risk. The calculated mean ERM quotient indicates the probability of heavy metals toxicity, equal to 21% in the examined stations.