جستجوی مقالات مرتبط با کلیدواژه « surface sediments » در نشریات گروه « پزشکی »

Heavy metals due to their ecological risks and high toxicity to living organisms are considered as one of the most dangerous pollutants. Therefore, the present study was conducted to investigate the level of pollution, toxicity and the ecological risks of heavy metals in the coastal surface sediments of Bushehr province using systematic review.

To conduct this review study, the concentration level of heavy metals in the surface sediments of Bushehr coastal was obtained by searching for published studies during the 9 years (2012-2020) through databases (Springer, Google Scholar, ProQuest, Web of Science, SID, Magiran). Finally, a comprehensive description of heavy metal pollution, toxicity and risks in coastal sediments was investigated using various indicators.

As a result of reviewing the extracted studies from the databases, 24 papers were selected. The survey results showed that the order of mean concentration of heavy metals in sediments was as Zn>Ni>Cr>Cu>Pb>Cd, and the amount of metals Pollution load index in different coastal sediments ranged from 0.15 to 1.99. The order of ecological risks for metals was observed as Cd>Pb>Ni>Cu>Cr>Zn, and the potential ecological risks for metals was obtained in the range of 3.76-257.38. In addition, the results of Toxic unit analysis and modified Hazard quotient of metals showed that the degree of toxicity and risk of contamination varies from very low to severely contaminated.

Based on the findings from the perspective of toxicity control and ecological risks of metals, it is necessary to prevent the transfer of heavy metals, especially Cd, Pb and Ni due to dominant human activities in the coastal areas of Bushehr. Also, due to the maximum pollution load and ecological risks in Bidkhon (Assaluyeh) coasts, pollution sources should be determined to effectively control and manage the entry of pollutants in this area.

This research was conducted of determining and comparing the heavy metals of zinc, iron, manganese, copper, nickel and vanadium in summer in waters and sediments of Naseri wetland in Khuzestan province, 2017.

Sampling of water and sediments from three areas of north, central and southern Naseri wetland was carried out in summer. In order to measure heavy elements, the ICP-OES model Varian 710-ES was used to measure the induction plasma (ICP) and its composition by mass spectrometry (ICP-MS).

The average concentration of heavy metals in Naseri wetland water was obtained at station 3 above the first and second stations. Zinc, iron, copper and vanadium were lower in the wetland water than national and international standards, but higher levels of manganese and nickel were obtained. The average of the concentrations of the studied metals except the nickel in the surface sediments of the wetland in the second station was higher than the first and third stations. Ni was found higher in the sediments of the third station.

The results of calculating the contamination factor showed that heavy metals were zinc, iron, manganese, nickel, vanadium and copper in low pollution levels. The degree of contamination of the studied metals also showed that pollution of Nasseri wetland sediments was low. The degree of contamination of modified heavy metals indicates very low contamination of sediments of Naseri wetland. The ecological risk of zinc, iron, manganese, nickel, vanadium, and copper was in the low-risk category. The total ecological risk of heavy metals at the stations was also classified as low risk.

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.

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. 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. 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. 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.