health and safety plan solid waste management unit assessment

JP-4 (JET FUEL 4) 64-3.8
The oxygenated products of photooxidation are generally more
water-soluble than the parent hydrocarbons and are thus more likely to
be leached from soil; enhanced toxicity of the oxygenated hydrocarbons
has also been observed (2248,2252). Larson et al. (2260) have reported
that in marine environments weathering of crude oils resulted in
decreased growth of algae.
64.2.2.2 Biological Degradation
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
land-farming waste disposal activities; 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). Hydrocarbondegrading
bacteria and fungi are widely distributed in marine, freshwater,
and soil environments. As reported in the review by Atlas
(2255), an extensive and diverse group of bacteria and fungi have been
shown to have the ability to degrade 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; however, Haines and Alexander (2254) showed that
n-alkanes up to C,, were metabolized. n-Alkanes are considered more
easily biodegraded than branched or cyclic alkanes; aromatics are
generally more rapidly biodegraded than alkanes.
The relative biodegradation susceptibility of petroleum
hydrocarbons has been summarized in a review by Bossert and Bartha
(2252): n-alkanes, n-alkylaromatics, and aromatics of the C,,-C,,
range are the most readily biodegradable; n-alkanes, alkylaromatics,
and aromatics in the C,-C, range are biodegradable at low
concentrations by some microorganisms but are removed by volatilization
and unavailable for biodegradation in most environments: n-alkanes in
the C,-C, range are biodegradable only by a narrow range of specialized
hydrocarbon degraders; and n-alkanes, alkylaromatics, and. aromatics
above C,, are generally not available to degrading microorganisms.
Hydrocarbons with condensed ring structures, such as polycyclic
aromatic hydrocarbons, hava been shown to be relatively resistant to
biodegradation. The biodegradability of some hydrocarbons may be
enhanced when present in petroleum mixtures.
Fatty acids and long chain n-alkanes not originally present in
weathered petroleum samples have been observed after biodegradation;
generation of tar balls which are quite resistant to microbial degradation
has also been reported.(2252,2255,2257,2258). Therefore, enhanced
solubilization or sorption of some metabolic intermediates (some
of which may be more toxic than the original hydrocarbons) may be
significant in the soil environment (2249).
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