Iranian Journal of

Background & Objectives: In recent years, enterance of oil contaminants especially polycyclic aromatic hydrocarbons (PAHs) to Anzali Wetland, has seriously threatened organisms life. Therefore, the current study was conducted to determine and compare concentration of PAH compounds with multiple sediment quality assessment indice to evaluate the ecological toxicity of surface sediments of Anzali Wetland and present appropriate management strategy. Materials & Methods: We randomly collected 22 surface sediment samples each sample was dried and extracted based on the soxhlet method. Then during two-step of column chromatography the PAH compounds were separated and analyzed by gas chromatography equipped with a mass spectrometry detector (GC-MS). Results: Total concentrations of these compounds ranged from 212 to 2674 ng g-1 d.w. with the mean of 907 ng g-1 d.w. The highest concentrations of PAHs was reported from stations (3-1 and 4-1) located in the vicinity of urban areas with shipping activities. In comparison with sediment quality guidelines (SQGs) used in this study, the concentrations of most PAH compounds in the majority of stations situated in low range values of adverse biological effects. Only in a few stations (3-1, 3-2 and 5-3), the concentrations of some of PAH compounds exceeded the low range of adverse biological effects. Conclusion: In comparison with sediment quality guidelines (SQGs) used in this study, the concentrations of most PAH compounds in Anzali Wetland rarely lead to adverse biological effects. However, concentrations of some of these compounds can cause acute toxic effects. Therefore, further studies including toxicity and bioaccumulation tests and survey of benthic community composition, especially in areas exceeded SQGs are essential for proper management.

Background and Objective: Mercury (Hg) is considered as a global pollutant that is widely dispersed in the environment. Monitoring of total mercury (THg) concentration in the sediments without determination of organic mercury (OHg) and selenium (Se) is an unreliable approach to evaluate the precise toxicological effects of Hg. In the present study, concentrations of THg, OHg and Se in the surface sediments of the eastern and western parts of Anzali wetland were investigated. In addition, the correlation of THg and OHg with Se and total organic carbon were analyzed.

Materials and Methods: Forty surface sediment samples were collected from the eastern and western parts of the wetland. Analysis of total and organic mercury in the sediment samples were done with Advanced Mercury Analyzer and the concentration of selenium was measured using inductively coupled plasma atomic emission spectroscopy (ICP-OES).

Results: The average concentrations of THg in the East and West wetlands were 109.53 and 68.39 ng/g dw, respectively. The average concentration of THg in the sediments of the eastern part of Anzali Wetland was significantly higher than that of the western part (P<0.001). The mean concentrations of OHg in East and West wetland were about 34.91 and 28.84 ng/g dw, respectively. There was  no significant relationship. The ratio of OHg to THg showed significant differences in the two studied areas. The average concentrations of Se in East and West wetlands were 156.25 and 163.75 ng/g dw, respectively. There was a significant negative correlation between the concentration of selenium and organic mercury in sediments of  the western part of  wetland (P<0.05).

Conclusion: The THg concentration in the sediments of Anzali wetland was lower in comparison to other studied regions of the world. However, the percentage of OHg in the Eastern and Western part of wetland was high. Therefore, bioavailability and toxicity of Hg would be high in the sediments and aquatic environment. In this study, in spite of high molar ratio of Se to THg, there was relatively high content of OHg. We recommend to measure the various Se-species that are effectively bound to inorganic Hg and to determine the amount of Se and Hg in aquatic organisms.

Background and Objective: Research has shown that assessing the toxicity and ecological risk of various types of pollutants, including heavy metals, using specific indicators, is indispensable in the ecological risk assessment of the ecosystem. Accordingly, the aim of this study was the assessment of the ecological effect of heavy metals presence (Pb, Zn, Cu, Cd and, As) in Anzali wetland using Heavy Metals Pollution Index (HPI).

Materials and Methods: 43 water samples were collected from the eastern, western and central parts of Anzali wetland. The samples were transferred to the laboratory, and the preparation steps were carried out using the ASTM method. Concentration of the elements was determined by Inductively Coupled Plasma -Atomic Emission Spectroscopy (ICP-AES). According to the concentration of heavy metals in the water samples, the index (HPI) was calculated. The results of the HPI index were classified into three classes: low risk (<15), moderate (15-30), and high risk (> 30).

Results: The numerical value of the HPI index was 3.59-23.3 with an average of 27.97, indicating the average level of heavy metals pollution in Anzali wetland. Indicator (HPI) in the eastern part of Anzali wetland and ​​the Pirbazar area showed a severe contamination and ecological hazard of the heavy metals and in the Abkenar region showed an acceptable ecological status.