health and safety plan solid waste management unit assessment

FUEL OILS 66-15
Natural ecosystems have considerable exposure to petroleum
hydrocarbons from natural emissions, accidental contamination through
oil spills and storage tank leaks, and deliberate application to land
in waste disposal activities such as land-farming; therefore, their
biodegradation is of environmental importance. Numerous authors have
observed the biodegradation of petroleum hydrocarbons, and several
extensive reviews and reports are available (1846,2252,2255,2249,
2253). An extensive and diverse group of petroleum hydrocarbondegrading
bacteria and fungi are widely distributed in the environment.
Although the microbiota of most non-contaminated soils include many
naturally occurring hydrocarbon-degrading populations, the addition of
petroleum selectively enriches that sector able to adapt and utilize
the'new substrate. Other environmental factors shown to have a major
effect on biodegradability are availability of oxygen and moderate
temperatures. The reader is referred to Chapter 64 for a more detailed
summary of the biodegradation of petroleum hydrocarbons,
The qualitative hydrocarbon content of petroleum mixtures largely
determines their degradability. In general, microorganisms exhibit
decreasing ability to degrade aliphatic hydrocarbons with increasing
chain length: aromatics are generally more rapidly biodegraded than
alkanes. The composition of diesel oil suggests that some of the
aromatic species will be biodegradable: biodegradation of the high
molecular weight aromatics expected to be present in residual oils will
be slower (2339).
In s-ary , biodegradation of the petroleum hydrocarbons
comprising diesel and fuel oils may occur under conditions favorable
for microbial activity and when fuel components are freely available to
the microorganisms. Degradation may be limited and/or slow in
environments with few degrading organisms, low pH. low temperatures,
and high salinity (e.g., arctic environments). It should be mentioned
that Walker s a. (2257) state that even under optimum conditions,
total and complete biodegradation is not expected to occur except
possibly over an extremely long time period.
66.2.3 Primary Routes of Exposure from Soil/Ground-water Systems
The above discussion of fate pathways suggests that pure fuel oils
have low vapor pressure but that their components vary in their
volatility from water. The components are strongly or very strongly
sorbed to soil. The polycyclic aromatic hydrocarbons in fuel oils have
a moderate or high potential for bioaccumulation, while the
longer-chain aliphatic compounds have low potential for
bioaccumulatfon. These fate characteristtcs suggest that the various
components may have somewhat different potential exposure pathways.
Volatilization of fuel oils from a disposal site or spill would
not be expected to result in significant inhalation exposures to
workers or residents in the area. Gravity would tend to carry bulk
quantities of the oil down towards the water table leaving only a
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