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BIOREMEDIATION OVERVIEW AND WORK PLAN ALTERNATIVES Years of research and thousands of applications around the world by government and industry have confirmed that common, non- pathogenic bacteria (and fungi ) are capable of the thorough aerobic degradation (mineralization) of many anthropogenic ' compounds- including fuel hydrocarbons , solvents, and pesticides . As aerobic degradation ends in the formation of carbon dioxide, minerals , and water, complete destruction of contaminants may be achieved. In addition, biological detoxification processes have proven to be cost effectivee- frequently affording savings of 50% or more when compared to conventional treatment and disposal methods . The science upon which biological detoxification is based is itself founded upon knowledge of the chemical and physical changes which occur in compounds (most often petroleum and petroleum products ) which have entered the environment as pollutants . While changes in the composition of polluting hydrocarbon mixtures are both chemically and biologically induced, biological (microbial ) degradation plays a mayor role in this process (known as weathering) . Although the complete breakdown of hydrocarbon materials into carbon dioxide, water, and minerals is theoreti- cally possible under virtually all circumstances , petroleum hydrocarbons are very complex mixtures containing large numbers of alicyclic, aromatic, and other compounds . Gasoline, for example, may contain 200 such compounds and crude oil many thousands . As each of these compounds possess distinctive physical and chemical characteristics , they differ in their capacity to serve as microbial substrates ( i .e . be utilized by bacteria as sources of carbon and energy) within a given environment. In addition, the physical state of the pollutants, environmental temperature, availability of oxygen and nutrients (particularly nitrogen, phosphorus , and iron ) significantly impact the rate of pollutant degradation. Clearly, the fate of fuel hydrocarbon contaminants within a given habitat will depend on the set of abiotic parameters particular to that habitat, with the interactions of multiple factors determining the overall rate of biodegradation. Factors such as favorable oxygen concentrations and a large surface �l area for microbial/contaminant interface could, for instance, be offset by low nutrient concentrations . Similarly, the favorable nutrient concentrations within certain soils may be offset by the presence of anoxic pockets of contamination within I. I