فهرست مطالب علی مهدی نیا

Polycyclic aromatic hydrocarbons (PAHs) are classified as an important category of semi-volatile and persistent organic pollutants. They cause environmental problems due to their toxicity and accumulation in sediments. In this research, offshore sediments of 19 stations in 8 transects of the Persian Gulf in Bushehr province were studied to assess the sources of PAHs. The extraction and clean up method were based on pressurized liquid extraction (PLE) with the cleanup by packed silica gel-based column. The compounds were analyzed by GC-MS. Recovery of the compounds was over 70%. The range of total 15 PAHs in sediment was from 6.5 to 35.5 ng g-1 sediment dry weight. The results showed that the levels of PAHs in the sediments were in the category of low pollution sediments. The highest concentrations of PAHs have been recorded in the station number 4 and 15 near the Kharg Island (Abouzar oil field) and Golshan oilfield, respectively. The cross plots of the diagnostic ratios of PAHs have come into common use as a tool for identifying and assessing pollution emission sources. Three cross-plots for the diagnostic ratios were applied in this study. They showed that the PAHs in the area had mixed sources of pyrogenic and pyrolytic. A progressive increase in the levels of PAHs was observed compared to the ROPME Cruise in 2006 that reflected more impact of anthropogenic activities on the sediments in recent years.

This study conducted to assess ecological risk of an important group of pollutants called polycyclic aromatic hydrocarbons (PAHs) in offshore sediment of the Persian Gulf deposits in Bushehr province. The aim of this study was to model the toxicity of PAHs for aquatic organisms in the study area. In the first step of the applied risk assessment model in this study, the unit of toxicity for each PAH and solubility were calculated by Quantitative Structure-Activity Relationships (QSAR) model. In the second step, the pore water concentration of all compounds in sediment was calculated as an available fraction. Finally, the proposed model was used to evaluate the offshore sediments of the Persian Gulf. Sediments in 19 stations and 7 transects were studied to assess the ecological risk of 21 PAHs. The extraction and clean up method was based on pressurized liquid extraction (PLE) with packed clean up cell. Compounds were analyzed by GC-MS. The toxicity and solubility of PAHs were modeled. The Pearson correlation for the predicted and measured data was more than 0.93. The amount of total toxicity was introduced as a risk index. The maximum and minimum total toxicity values for the sediments were found as 0.018 and 0.147, respectively. The results from this study indicated that although the concentration of PAHs in the sediments may not cause significant concern in the study area, they may affect benthic organism at the sub-lethal levels. According to the applied risk assessment model for 21 unsubstituted PAHs, the offshore sediments of Bushehr are in low-risk range. The result of this study indicated a low risk of the sediments. The hazard index decreased as the distance from coastal and oil and gas industry increased, indicating the high impact of anthropogenic activities on the contamination of the study area.

Mollusks are remarkably appropriate as a bio-indicator due to their wide geographical distribution, high abundance in benthic environments, selective absorption of certain ions and their motionless nature. Chiton, a mollusk of the phylum of Polyplacophora, and of its lamyi species is abundant in Chabahar Bay coastal rocks. Based on previous studies, this animal can be introduced as a potential indicator of Ecosystem Health; hence Chiton was chosen to be investigated rate of accumulation of metals, Cd, Cu, As and Hg in Chabahar Bay. After sampling four major stations, the samples were prepared and Cold Vapor Atomic Absorption apparatus were used for measurement of mercury and graphite furnace method was used for measuring other metals. Then, using the obtained data, bioaccumulation factor was calculated for each metal separately in the maximum amount of cadmium bioaccumulation factor at station 4 (Great sea) (136.34±0.02) and the lowest mercury at station 2 (Coast of Maritime University) (1.88±0.02), respectively. After statistical analysis of the results, it was found that Chiton can be introduced as a bio-indicator of the mentioned contaminants in the coast of Chabahar Bay.

In this study, concentrations and origins of 15 PAHs in intertidal sediments of North Pars Special Economic Energy Zone were investigated. Samples were collected from 20 stations (during low tide and randomly) before establishment and running in June 2011. Samples were analyzed by HPLC. Fluoranthene in Melgonze 2 showed the highest levels of PAHs and Dibenzo[ah]anthracene in Chahpahn 1, Chahpahn 2, Zirahak 1, Kabgan1, Kabgan 2, Kabgan 4, Bordekhon 3, Bordekhon 4, Demeigez 1 and Demigez 2 were the lowest ones in the study area. Results revealed that there were relatively low levels of ΣPAHs in the sediments. Sediment in the study area is being subjected to a combination of pyrogenic and peterogenic with pyrogenic prevalence origin. It could be concluded that in the study area, pollution amounts were much lower than the compared standards and the potential hazard for benthic assemblages seemed to be low.

Anzali Lagoon is an internationally protected lagoon located in west-south of Caspian Sea which has special ecologic, economic, social importance with vast diversity of plants and animals. According to entrance of contaminants into this lagoon, concentration of several heavy metals in muscle of Esox lucius fish have been investigated in this study. First stage of sampling from three stations of lagoon, have been fulfilled at dry season of September and second stage have been implemented at rainy season of November 2010. In each season nine samples of fish have been collected and transported to laboratory in freezed condition. Evaluation and measurement of heavy metal concentration has been fulfilled by Graphite furnace atomic absorption equipment. Maximum mean concentration of Hg, Ni, Se, Zn, Al, and Fe have been detected in the summer and maximum mean concentration of Cu has been detected in the winter. Maximum mean value of Hg, Ni, Zn,Al in Abkenar, maximum mean value of Se in Siah Darvishan and maximum mean value of Cu, Fe in Komeh Aghajani have been detected, while concentraton of Mo, Cd, V and Pb are equal in the three above mentioned stations. Statistical analysis of this study has been fulfilled by SPSS, V14 software. Pearson correlation test, showed a positive strong correlation between temperature and the amount of Fe (r=0.83, P<0.05). Only significant difference in concentration of Fe has been obtained between summer and winter seasons (P=0.016, df=16, P<0.05). Significant difference in concentration was detected only for Hg between Abkenar and Komeh Aghajani stations (P=0.05).This study shown that, the concentration of Ni, Hg, and Cd in the muscle of Esox lucius are high and it is considered as a serious warning.

Polycyclic aromatic hydrocarbon (PAHs) is one of the most important environmental pollutants which originated from various sources. They are stable in seawater and especially in sediments and their degradation occur slowly. Sixteen numbers of this pollutant are introduced by Environmental Protection Agency (EPA) as serious carcinogen compounds. In this study، the contents of 16 PAHs compounds were determined in the sediments of Hormoz straight، Persian Gulf. The sampling was performed by Van Veen grab from 11 sites of Iranian waters of Hormoz straight. Determination of PAHs were performed by high performance liquid chromatography equipped with fluoresce detector. The results showed that the total concentration of PAHs varied between 72. 17- 191. 70 ng g_1 dry weight of sediments. Maximum individual concentration of PAHs was 19. 72 ng g-1 belonged to flouranthene. Dibenzo (a،h) anthracene and flourene were not detected in all of the sampling sites. The total organic matters (TOM) of sampling sites were different from 8. 25 to 2. 75%. Comparison of PAHs concentrations in the studied sediments with that of other places in the world showed that the PAHs pollutions of studied sediments are medium to low. The results also showed that the source of PAHs pollutants can be attributed to the pyrolitic sources.

Concentrations of PAH’s known as carcinogenic compositions were studied in the muscle of Pike fishes (Esox lucius) in Iranian international wetland of Anzali in year 2010. Fifteen samples were taken at three stations of Mahruzeh, Koumeh Aghajani and Siah darvishan in dry (early September) and wet (early December) seasons. Some environmental parameters like pH, dissolved oxygen and water temperature were also measured at the same time. Biometry and age determination were done for each sample prior to their preparation for measurement of PAH’s concentrations using HPLC method. Acenaphtene with the concentration of (31.9 ± 11.37 ppb) and Benzo[a]pyrene with (0.2 ± 0.1 ppb) were the highest and lowest recorded concentrations in each season respectively. In both seasons, significant negative correlations (P<0.05) were observed between Naphthalene and Acenaphtene with fish age (2 year and under 1 year) and also between Benzo[b]fluoranthene and Benzo[ghi]perylene with dissolved oxygen. In both seasons, significant correlation were observed between dissolved oxygen and pH with PAH’s while  between PAH’s and fish weight it was significant only in cold season (P<0.05).Considering the 52.63 ppb (dry weight) as the highest measured concentration of PAH’s in this study and 30 µg/kg (wet weight) as the maximum allowable contamination level for aquatic organisms it can be concluded that the PAH’s concentration in Pike’s muscle is almost within the allowable limit in Anzali Wetland.