Hydrochemical characteristics of the United Arab Emirates waters along the Arabian Gulf and the Gulf of Oman

Abstract

        Seawater samples were collected bimonthly from the United Arab Emirates territorial waters, which extend for more than 800 km along the Arabian Gulf and the Gulf of Oman. In this paper, the levels and distributions of temperature (20.0-34.5°C), salinity (35.4-42.3 psu), pH (7.21-8.38), transparency (4.0-26.0 m), dissolved oxygen (2.24-6.19 ml l^-1; 43.4-155.5 sat. %), and permanganate value (oxydizability) of dissolved organic matter (0.1-30.8 mg O₂l^-1) are presented. Temperature variations in both areas were as usual in the region, i.e., maximum in summer and minimum in winter. The distribution of temperature revealed higher values (27.7°C) in the Arabian Gulf waters compared to the Gulf of Oman (26.3°C) suggesting higher evaportic conditions. Due to the higher rate of evaporation, the Arabian Gulf waters showed also higher salinity (39.2 psu) compared to the Gulf of Oman (36.4 psu). Regarding the pH, the two regions displayed very limited seasonal and regional variations without significant differences. Transparency, however, showed wide variations in the two regions with higher values in the summer season than the winter season. The seawater in the Gulf of Oman was more transparent than the Arabian Gulf waters. In the meantime, the Arabian Gulf and the Gulf of Oman waters contained nearly similar concentrations of dissolved oxygen, with higher values in the winter season than the summer season. The concentrations of the permanganate value (oxidizability) of dissolved organic matter indicated higher values in the seawater of the Arabian Gulf than the Gulf of Oman, with higher values in the summer season than the winter season. Moreover, pronounced increase in the concentrations of permanganate value (oxidizability) of  dissolved organic matter was observed with depth with depth in the two regions. The amounts of oxygen that present after complete oxidation of organic matter in the Arabian Gulf and the Gulf of Oman were found to be 48.8 and 51.7%, respectively.