فهرست مطالب فاطمه باطنی

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.

Landscape characteristics and land use patterns of watershed demonstrate extension, distribution, density and abundance of human interference. These factors can affect water quality of adjacent aquatic systems within a watershed. Land use changes have caused various environmental problems for Zayandehroud River,turned it as a sink of pollutant. Therefore this is investigated that how would Landscape characteristics and land use patterns change water quality and affect ecosystem management. The main goal of this study was to examine how landscape patterns (including Number of Patches, Edge Density, Percentage of landscape, Total Edge and Largest Patch Index) influence water quality. Indexes (including EC, HCO3, NO3, Cl, K, Ca, COD, Na, DO, P, pH, BOD5 and TDS) were measured in 10 stations along the Zayandehroud river.This is one of the most important rivers of the central plateau of Iran.In this study, Four classes of land use including Cropland, Orchard, Residential and industrial area were identified in a period of eleven years (1997–2008). The results indicated that water quality was significantly correlated with both proportions and configuration of Residential areas. Total edge of Industrial area had negative effects on water quality, especially on TDS and COD. Results of this study can be used not only for resource managers in order to restore the aquatic ecosystems but also for policy makers in evaluating alternate land management decisions.