ADSORPTION TO SUSPENDED PARTICLES 



Dispersed oil will adsorb to clays and other fine sediments in seawater, 

 and eventually this sediment, with attached oil globules, is carried to the 

 bottom (Poirier and Thiel 1941). In estuarine areas that are characterized 

 by fine sediment salt marshes, the amounts of suspended particles in the water 

 are high and oil in this turbid area is soon carried to the bottom. Adsorption 

 to suspended particles is an important process for high weight aromatic and 

 aliphatic hydrocarbons which have low water solubility. These particles 

 include clays, detritus, living photoplankton, and microbes. Studies off 

 the coast of Georgia have shown that most dissolved hydrocarbons adsorb to 

 detrital particles, which are a mixture of organic matter, living bacteria, 

 and small clay particles (Lee 1977). Scanning electron micrographs reveal 

 rough surfaces on these detrital particles, with bacteria fastened by mucoid- 

 like pads and fibrilla appendages. Lower weight hydrocarbons and more polar 

 petroleum components remain in the water and show little adsorption to particles 



BIODEGRADATION 



It is commonly assumed that microbes are the major degraders of oil in 

 the sea. Hydrocarbon-degrading bacteria and fungi have been isolated from 

 both polluted and pristine water (Zobell 1971, Floodgate 1972, Gunkel 1973, 

 Walker and Colwell 1974). Hydrocarbon-degrading microbes are generally more 

 abundant in areas of chronic oil pollution than in petroleum-free areas (Atlas 

 and Bartha 1973). Through the use of radiolabeled hydrocarbons, it has been 

 found that microbes in inshore and offshore waters are important in degrading 

 phenols, lower weight aromatics, and aliphatics, but not higher weight aro- 

 matics (Lee and Ryan 1976, Lee 1977). 2 Estuarine waters show higher rates 

 of hydrocarbon degradation than offshore waters, presumably because of the 

 higher bacterial biomass associated with estuaries. Microbial breakdown of 

 higher weight aromatics, such as benz(a)anthracene and benzo(a)pyrene, is 

 probably not so important in ocean waters. Larger organisms, such as zoo- 

 plankton, can take up and degrade these hydrocarbons (Lee 1975, Corner et 

 al. 1976). After sedimentation of hydrocarbons, sediment microbes metabolize 

 polycyclic aromatic hydrocarbons. 



Input of oil into marine waters results in large increases in petroleum- 

 degrading microbes, which will attack the various slicks, emulsions, disper- 

 sions, and soluble components that are produced. Most of a fuel oil water 

 extract added to a large controlled ecosystem enclosure (2 m diameter and 15 

 m deep--60,000 1) in western Canada was biodegraded after 14 days (Lee 

 and Takahashi 1977, Lee et al . 1977a). Three days after fuel oil addition, 

 naphthalene degradation increased from 0.2 to 2.5 yg/l/day (turnover time 

 decreased from 500 days to 10 days). Large clumps of petroleum-degrading 

 microbes were observed, which were absent after the fuel oil components were 

 degraded. Using a continuous growth chamber, Gibbs (1975) found that degra- 

 dation of a Kuwait crude was 30mg/l/year in water from the Irish Sea. The 

 temperature and concentration of nutrients (nitrogen and phosphorus) are 

 important in determining the rate of biodegradation. Atlas and Bartha (1973) 

 found that the number of oil -degrading microbes was very low during the winter 

 in Raritan Bay. Other workers have noted slower degradation of crude oils 

 and oil components in the winter (Floodgate 1972, Lee 1977). 



_ 



This work was supported by NSF/IDOE, Grant No. IDO OCE 74-05283 A01. 



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