Abstract
The coast of the Gulf of Aqaba is subjected to several sources of pollution due to several activities occurring at the coastal area. The activities vary between industrial, tourist and other development aspects at the Jordanian coastline of the Gulf of Aqaba. Phosphate industry has been considered a major source polluting the marine environment. According to official reports, 4-7 million tons of raw phosphate is exported through the Gulf of Aqaba. During transportation and loading, a small proportion of this enters the waters of the Gulf. Phosphate dust has also been considered another source of nutrients loading to the Gulf. 19 sediment samples were collected along the Saudi Gulf coastline, from the Saudi-Jordan border down to the end of the Gulf at Tiran Strait. Measurements of the activity concentrations of super(226)Ra, super(232)Th, super(40)K and super(137)Cs in Bq/kg (in dry weight) of the collected samples were carried out using gamma-ray spectrometry based on a highly pure germanium coaxial detector (HPGe). The concentrations of super(238)U and super(232)Th were also determined using ICP-MS technique. The average specific activities for super(226)Ra, super(232)Th, super(40)K and super(137)Cs were found to be 11.4+/-1.5, 22.5+/-3.7, 641.1+/-61.3 and 3.5+/-0.7 Bq/kg, respectively. The results show that the mean activity of super(226)Ra and super(232)Th is lower than the world average of 25 Bq/kg for both of them, whereas the mean value for super(40)K is about double the world average of 370 Bq/kg. The presence of super(137)Cs in the analyzed samples is low in most locations. The mean concentrations of super(238)U and super(232)Th in the study area are 1.2 and 5.4 mg/kg, respectively, and the ratio super(238)U/ super(232)Th is 0.2, which is lower than the global ratio of 0.3. The ratio of super(226)Ra/ super(228)Ra was found to decrease southwards in the direction of Tiran Strait, away from the phosphate industry in Jordan. Mean values for radium equivalent, absorbed dose, annual effective dose, external and internal hazard index and representative level index were determined as: 92.9 Bq/kg, 45.6 nGy/h, 56.0 mu Sv/y, 0.13, 0.28 and 0.73, respectively.