Document Details
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Document Type |
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Thesis |
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Document Title |
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Biogeochemistry of Selenium in the Red Sea بيوجيوكيميائية السلينيوم في البحر الأحمر |
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Subject |
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Faculty of Marine Sciences |
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Document Language |
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Arabic |
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Abstract |
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Selenium as a nonmetal element with bilateral properties has been subject to extensive studies during the last hundred years. This is due to its chemical, biological, and physiological importance for a human being, animals, and plants. The aim of this thesis is to investigate selenium by determination, distribution, sources, behavior, and its relationship with the physical and chemical properties of the Red Sea water. The study was conducted in the eastern Red Sea water to cover open sea water, some polluted lagoons, and one desalination plant.
In the lagoons, total dissolved selenium (TDSe) showed a high concentration with range between 0.16 and 74.09 nM and average of 5.15 nM which exceeds the permissible level established by the World Health Organization (WHO) and the Food and Agriculture Organization (FAO) in Al-Arbaeen lagoon and Sharm Obhur. The relationships of the TDSe against nitrate, phosphate, and DIN revealed clearly its role as the nutrient and its participation in the biological processes. The source of pollution was identified using the TDSe correlation versus the salinity and the selenium surface horizontal distribution. The data revealed that pollution source was mainly due to the waste water discharging. The TDSe showed a conservative mixing behavior in the lagoons. The TDSe relationship with the chlorophyll a and the total organic carbon revealed its utilization by phytoplankton and the possibility of selenium uptakes and releasing from dissolved organic matter in the lagoons. The TDSe relationship with the dissolved oxygen showed that the redox reaction has an important role in controlling selenium biogeochemistry. The pollution was very clear figured out from the nutrients and salinity measurements in Al-Arbaeen compared with Reayat Al-Shabab lagoon. This can be referred to the problems in circulation with open sea water due to the Jeddah Islamic Port which hinders the water exchange in Al-Arbaeen lagoon. In two fish species selenium were exceeded the permissible level.
In the open sea water, the surface TDSe revealed low concentration compared with the other seas and oceans. It showed a high concentration in front of Duba and Ummluj surface coastal water due to the valleys input. In the three transects, it showed a high coastal water concentration decreased towards offshore due to the dilution effect. It did not show the nutrient type profile in Rabigh and Duba. In agreement with the previous studies, the surface temperature recorded a high value in the middle part in front of Jeddah and decreased northward in front of Duba. Similarly, the surface pH and chlorophyll a showed the same variation patterns due to productivity. The nitrate revealed a high concentration in front of Yanbu and Al-Wajh due to the valleys input and anthropogenic effect. In the same regard, the phosphate showed a high concentration in the northern part of the Red Sea in front of Yanbu, Al-Wajh, and Duba. In all transects except for Duba, the TDSe correlation with nitrate and phosphate reflected its role as nutrient and its contribution to the biological processes. It showed a significant positive correlation with the salinity which indicates that conservative behavior. The correlation of TDSe with total organic carbon and chlorophyll a revealed that selenium can be utilized by phytoplankton through the uptakes and can be released through the organic matter remineralization. |
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Supervisor |
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Dr. Radwan Khalid Al-Farawati |
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Thesis Type |
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Doctorate Thesis |
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Publishing Year |
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1438 AH
2017 AD |
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Added Date |
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Wednesday, July 12, 2017 |
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Researchers
| أحمد سيف الدين إبراهيم | Ibrahim, Ahmed Saif Aldein | Researcher | Doctorate | |
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