Assessment of organic pollutants in the offshore sediments of Dubai, United Arab Emirates

Abstract

Fifteen stations (st) were selected along Dubai coastal region to delineate the distribution and the source of total petroleum hydrocarbon (TPH), total organic carbon (TOC), total Kjeldhal nitrogen (TKN), polycyclic aromatic hydrocarbon (PAHs) and polychlorinated biphenyls. The concentrations of TPH fluctuated between 2 μg g −1 and 48018 μg g −1 and the values of TOC were in the range of 0.16–5.9 wt%, while TPAHs ranged from 0.09 μg g −1 to 161.72 μg g −1. On the other hand, TPCBs showed values between 0.8 μg kg−1 and 93.3 μg kg−1 and TKN values varied from 218 μg g−1 to 2457 μg g −1. Distribution of oil and organic compounds in Dubai sediments are safe compared with previous studies except for limited areas at the northeastern offshore. These readings are probably due to: (1) presence of commercial or industrial ports, dry docks and fishing harbours and (2) population centers mainly concentrated at the northern part of the study area. Results indicate that TOC can be used as indicator of oil pollution only in heavily oiled sediments. The highest values of TOC, TPH, TPAHs and TPCBs corresponded to the stations covered with fine sand, due to adsorption properties and larger surface area. The evaporation of low boiling point compounds from surface layers led to enrichment of sediments with the thick residual. Al-Hamriya St 3 exhibited the highest values of TPH, TOC, TPAHs and TPCBs and the second highest value of TKN.