Date of Award
Master of Science in Oceanography
James G. Quinn
Water samples from Narragansett Bay, the Providence River, the Sargasso Sea, and fulvic acid/saline (NaCl) solutions were examined for their ability to solubilize n-alkane (n-C16, n-C20), isoprenoid (pristane), naphthenic (tetradecahydrophenanthrene) and aromatic (phenanthrene, anthracene) hydrocarbons. A 30-80% reduction in the dissolved organic content of the natural samples by activated charcoal and by ultraviolet oxidation resulted in 50-99% decrease in the amount of saturated hydrocarbons solubilized. This decrease was directly related to the amount of dissolved organic matter (D.O.M.) removed. The solubilities of the aromatic hydrocarbons were unaffected by the D.O.M. The solubility of phenanthrene is twenty times greater than its structural isomer, anthracene, regardless of the concentration of D.O.M.
Fulvic acid from a marine sediment, surface active organic material isolated at a chloroform/sea water interface, organic material extracted from a marine sediment by sea water, organic matter associated with a municipal sewage effluent, fulvic acid from a muck soil, and humic acid from a marine sediment promote n-alkane solubility when added to saline solutions and reenhance solubility when added to organic depleted sea water. The solubility of No. 2 fuel oil increased 2.5 times in the presence of fulvic acid in saline solutions and was 1.5 to 2.0 times greater in Narragansett Bay water than in charcoal treated bay water. Most of the increase is seen in the n-alkane and isoprenoid components of the fuel oil.
N-alkane solubility in fulvic acid/saline solutions with increasing pH and reaches a maximum with respect to ionic strength at I = 0.3 in NaCl solutions and at I = 0.2 in sea water. There is evidence to suggest that the mode of solubilization of the hydrocarbons is by association with micelles formed by the surface-active humic-like monomers. The presence of ionic species is a prerequisite for micelle formation and hence solubilization.
The surface microlayer of the Sargasso Sea, which was enriched 1.8 times in dissolved organic carbon relative to the subsurface water, solubilized n-alkane hydrocarbons while the subsurface water showed no ability to solubilize these materials.
Boehm, Paul David, "Solubilization of Hydrocarbons by Dissolved Organic Matter in Sea Water" (1973). Open Access Master's Theses. Paper 2079.