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.

Over the past decades, overall ecological conditions in the Caspian Sea have deteriorated. However, a comprehensive understanding of lake-wide spatial differences in anthropogenic pressures is lacking and the biological consequences of human impacts are poorly understood. This paper therefore aims at assessing the individual and combined effects of critical anthropogenic pressures on the Caspian Sea ecoregions. First, cumulative pressure scores were calculated with a cumulative environmental assessment (CEA) analysis. Then, the individual contribution of anthropogenic pressures was quantified. Finally, ecoregion-specific differences were assessed. The analyses show that both cumulative and individual pressure scores are unevenly distributed across the Caspian Sea. The most important individual pressures are invasive species, chemical pollution and poaching. This uneven distribution of pressure scores across Caspian Sea ecoregions creates new challenges for future conservation strategies, as different ecoregions usually require different conservation measures.

The main objectives of the present study were to measure the concentration of mercury in Alosa spp. muscle tissue and to assess the health risk to consumers. For this purpose, fish samples were collected from four regions of the southern coast of the Caspian Sea. Mean concentrations of mercury in the regions of Bandar Torkaman, Feridonkenar, Chalos and Bandar Anzali were 264.10, 73.74, 161.90, and 183.80 μg g−1 dw, respectively. The mercury averages obtained in all four regions were below the standards recommended by the World Health Organization (WHO), the Food and Agriculture Organization (FAO), the Standardization Administration of China (SAC) and the Joint FAO/WHO Expert Committee on Food Additives (JECFA). The values of hazard quotient also showed no potential health risk for consumer. However, the assessment of other contaminants is recommended for more accurate conclusions about the health risks of consumers through the consumption of the fish.

The Caspian Sea is the largest land-locked lake in the world that includes numerous endemic species. Because of its enclosed nature, the pollutants entering this water body become entrapped. The present paper examines the influence of human activity and beach morphology on the abundance and distribution of stranded plastic debris along the Caspian Sea coastlines. It would be possible by relating some characteristics of these beaches (population, urbanization, substrate type, and slope of beaches) with the abundance of plastic debris through a PCo analysis. The results showed that in our study area, the most effective factors on plastic debris distribution were urbanization and population followed by the slope and substrate of beaches. Three size classes of plastic debris were defined as “large microplastic” (1 to < 5 mm), “mesoplastic” (5 to < 25 mm), and “macroplastic” (> 25 mm). The density of the large microplastic, mesoplastic, and macroplastic materials on the Caspian Sea coastline was 8.43 ± 0.54, 8.74 ± 0.42, and 7.53 ± 0.30 particles/m², respectively. Foam was the most abundant microplastic debris along the study area (47.58%), followed by resin pellets (33.93%) and fragments (16.30%), respectively. We also selected the Boujagh National Park with limited accessibility as an appropriate area for the study of marine debris as one sampling station. Cigarette butts and film pieces displayed a different distribution pattern compared to other debris types in the Boujagh National Park station likely due to their distinct buoyancy specification.