health and safety plan solid waste management unit assessment

JP-4 (JET FUEL 4) 64-19
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. The available review articles (citing
laboratory studies and field studies) confirm that the distribution of
hydrocarbon-utilizing microorganisms reflects the historical exposure
of the environment to hydrocarbons (2252,2255,2257,2249). In
unpolluted ecosystems, hydrocarbon utilizers generally constitute less
than 0.1% of the microbial community; in oil-polluted ecosystems, they
can constitute up to 100% of the viable microorganisms (2255). Walker
s A. (2257) reported that all classes of petroleum hydrocarbons were
degraded by microorganisms in an oil-exposed sediment but not in a
similar unexposed sediment.
Biodegradability has been shown to be related to JP-4 hydrocarbon
concentrations. When concentrations are too low, biodegradation may
cease. However, at high concentrations the components or their
metabolic intermediates may be toxic and inhibit degradation (2249).
Biodegradation of petroleum hydrocarbons has also been shown to be
dependent on other environmental factors including: temperature,
oxygen and moisture, nutrients, salinity, and pH (2252,2249,2255,1846).
Petroleum biodegradation has been reported to occur over a wide range
of temperatures: Huddleston -and Cresswell (2261) reported
biodegradation at -1.l'C; Dibble and Bartha (2262) reported that the
highest rates occurred between 3O'C and 4O'C with no increase observed
above 37'C; and Atlas and Bartha (2263) reported that the degradation
rate roughly doubles with each 5-C increase in the-5' to 20-C range;
degradation in arctic environments has been reported to be dramatically
reduced (2255,2266).
Oxygen has been'reported to be necessary for the initial steps of
hydrocarbon degradation; reports of anaerobic degradation have been
sporadic and controversial (2252,2255,2249). Oxygen depletion has been
shown to lead to sharply reduced hydrocarbon utilization in soils
(2261). Tilling of soil has been shown to have a positive effect on
petroleum degradation (1811,2256).
In the presence of large quantities of hydrocarbon substrates, the
availability of nutrients, particularly nitrogen and phosphorus,
becomes' increasingly important and the addition of fertilizers has a
notable positive effect on biodegradation (2249.2252.2255); in subsoil
treated with l-10% oil, the addition of fertilizer had little effect
(2256).
There are limited data available on the effects of pH and salinity
on biodegradation of'petroleum. In general, degradation was reported
to decrease with increasing salinity (2249) although the effect of
different microbial populations in the experiment was not determined.
Hydrocarbon degradation was reported to be low in naturally acidic
soils and increased up to pH 7.8 (2262).
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