Date of Award
Master of Science in Oceanography
James G. Quinn
A method which allows the measurement of the concentration of hydrocarbons and phthalic acid or phthalic acid esters in a single sea water sample is described. The average hydrocarbon concentration for 36 sea surface microlayer samples, approximately the top 300 microns was 94 μg/l with a range of <4 to 559 μg/l. The hydrocarbon concentration for 36 subsurface samples, approximately 20 cm below the surface, averaged 51 μg/l, with a range of <2 to 248 μg/l. Comparisons of sample pairs, sea surface microlayer and subsurface from each station, reveal that 71% have greater hydrocarbon concentrations in the sea surface microlayer than in the subsurface.
The average phthalic acid concentration for 10 sea surface microlayer samples was 0.9 μg/l (range of 0.1 to 3.2 μg/l), while the average value for 7 subsurface samples was 0.4 μg/l (range of <0.1 to 1.0 μg/l). The average di-2-ethylhexyl phthalate (DEHP) concentration for 3 sea surface microlayer samples was 4.0 μg/l (range for 3.2 to 4.6 μg/l) and the average concentration for 3 subsurface samples was 1.3 μg/l (range of 0.7 to 2.5 μg/l). All but one of the samples measured for phthalic acid and DEHP had greater concentrations in the sea surface microlayer than in the subsurface.
Pelagic tar was found to be a possible sources of petroleum hydrocarbons found in the Sargasso Sea waters. This material, as analysed by gas liquid chromatography, averaged 23% hydrocarbon, based on the dry weight of tar. Atmospheric transport and deposition are possible sources of phthalic acid in the open ocean samples.
Wade, Terry L., "Measurements of Hydrocarbon, Phthalic Acid, and Phthalic Acid Ester Concentrations in Environmental Samples" (1974). Open Access Master's Theses. Paper 2295.