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Showing 2 results for Surface Sediments

M Zamani, N Khorasani, A.r Riahi Bakhtiari, K Rezaei,
Volume 7, Issue 4 (1-2015)
Abstract

Background and Objectives: This study was performed to determine and identify the origin, concentration and source of perylene entry and some PAH compounds in surface sediments of Ghalam Goodeh (A), Siyah Kashim (B), and Talab Markazi (C) in Anzali wetland. Materials and methods: We collected 22 samples of sediments (from each region) and 2 samples of soils (from A region) in April of 2012. Sampling was performed from soil for proving the condition of concentration and origin of perylene in under investigating sediments. GC-MS was applied for extraction of PAH compounds using organic solvents and 2-phase column chromatography. Diagnostic ratios of Ph/An, Flu/Pyr, Flu/Flu+Pyr, BaA/BaA+Chr and IP/IP+BghiP were used to determine the origin of PAH compounds. Results: In all sediment samples, the origin of perylene and PAH compounds were found to be natural and petrogenic, respectively. The total concentration of PAH compounds were ranged between 560.05 to 1051.93 ng/g dry weight and perylene concentration were obtained between 70.65 to 204.41 ng/g dry weight. Total concentration of PAHs and perylene was significantly more in area A compared with other two area, whereas no relationship was found between normalized values of PAHs and TOC in sediments of all areas. Conclusion: With respect to the petrogenic source of PAHs in the surface sediments, the main sources of the PAH compounds entry are the discharge of domestic and industrials wastewater, the port and shipping activities, the exploration, excavation and refining activities of crude oil in offshore region and transportation of fishing and tourism boat but diagnosis of natural origin of perylene in the samples of surface sediment and soil implicated that this compound can be produced in terrestrial section due to activity of termites and fungi on the woody and cellulosic materials of forest floor, decaying wood and their fossilized remains and then their discharge to the wetland.


F Bateni, A Mehdinia, M Seyed Hashtroudi ,
Volume 11, Issue 4 (3-2019)
Abstract

Background and Objective: 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.
Materials and Methods: 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.
Results: 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.
Conclusion: 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.
 


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