Oil pollution in the Persian Gulf and approaches, 1978

Vessel reports of oil slicks in the Persian Gulf and approaches during 1978 show an increase in number and percentage of positive reports towards the Strait of Hormuz. Pronounced seasonal variations in slick characteristics include an increase in number, size and areal coverage during winter, but an increase in thickness of slicks in summer. High solar radiation enhances photolysis, evaporation, solution and bacterial degradation of oil. Slick dispersal patterns agreed with prevailing wind and surface current circulation. Most slicks appeared to represent separate events. Of the ten major slicks, which were all ‘thin’, seven were reported by two out of 84 vessels. Collectively, they contained 73% of all oil in 139 reported slicks. Using an average of 13 μm for the thickness of ‘thin’ slicks, the largest slick contained more than 54 000 m³, and all slicks combined totaled 160 000 m³. Two independent alternate estimates confirm this computation within 10%.