The effect of bioremediation on microbial populations in AN oil-contaminated coastal wetland
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abstract
A series of controlled crude oil applications was carried out in a Texas coastal wetland to determine the effectiveness of bioremediation in these sensitive areas. The first application, conducted in 1996, was performed to assess the use of diammonium phosphate and diammonium phosphate plus a potential electron acceptor (nitrate) to stimulate microbial growth and subsequent hydrocarbon degradation. The second application, conducted in 1997, was performed to determine the potential of two commercial bioaugmentation products to enhance hydrocarbon biodegradation. Diammonium phosphate was also reevaluated during this phase as a biostimulation treatment. For both applications, sediment samples from all oiled test plots showed exponential increases in the numbers of aliphatic hydrocarbon and polycyclic aromatic hydrocarbon (PAH)-degrading microorganisms. Average numbers of aliphatic-degrading and PAH-degrading microorganisms were slightly higher (though not significantly higher) than populations on oiled control plots on most sample days. The bioaugmentation products and diammonium phosphate treatment examined during the second application did not significantly increase the numbers of hydrocarbon-degrading microorganisms (aliphatic-degraders or PAH-degraders). Overall, the microbial populations from both phases of research illustrated a well-documented response to a petroleum hydrocarbon input. Although the bioremediation treatments did not appear to significantly increase these populations, this data will be evaluated with nutrient and petroleum hydrocarbon data to determine the effectiveness of bioremediation in wetland areas.
