MEASUREMENT AND INTERPRETATION OF NONVOLATILE HYDROCARBONS IN THE OCEAN. PART I. MEASUREMENTS IN ATLANTIC, MEDITERRANEAN, GULF OF MEXICO, AND PERSIAN GULF

Little quantitative data are available on the amount and composition of hydrocarbons in the sea. To obtain such data, water samples were taken from tankers along four main routes in the Atlantic and adjacent seas and in other locations from oceanographic research vessels. Floating oil or tar balls were not collected. The water samples were extracted with carbon tetrachloride. The amount of extractable organic material and the amount and composition of nonvolatile hydrocarbons were measured. Hydrocarbons (with a mean of 4 ppb) were log-normally distributed in the samples collected through the top to meters of the water column. In deeper ocean waters hydrocarbon content generally declined with depth, and the median value was less than 1 ppb. Based on relative amounts of hydrocarbons and of total CCL4 extractable material, it is estimated that the hydrocarbons are mostly petroleum-derived in locations where petroleum input into the sea is likely. Additional work is needed to confirm and extend these findings.