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Carbon Dioxide Produced by Biodegradation of TPH Carbon dioxide was produced in the head space of the jars due to biodegradation of TPH, PAM and organic matter contained in the soil. Figure 2 shows the plot of COZ as a function of time for all treatments. The control treatments, F, have a low amount of COZ as shown in Figure 2. Biodegradation of TPH and PAM are responsible for most of the production of COz in our contaminated soil. There was a slight disappearance of PAM as shown in Table 13 of Khaitan (23) for treatment E, so biodegradation of TPH was the primary source of COz produced in the microcosms. The rate of COz production was high initially and then the rate slows down gradually as can be seen from the slopes of the graphs in Figure 2. Treatment B produced the largest amount of COz as it contained the largest amount of TPH. Initially, treatment C produced COZ at a high rate and then the rate became very low at t=13 weeks due to the decrease in concentration of TPH. From the TPH plot as a function of time in Figure 1, disappearance of TPH in treatment C is nearing completion, which results in a corresponding reduced rate of production of COz. Treatment D continued to produce COz at almost the same rate as shown from the plot in Figure 2; there was a corresponding decrease in the TPH toward the end of the experimental time period of 23 weeks. Biodegradation of TPH in treatment D may be able to continue for a few more weeks as biodegradation does not appear to be near completion. The same reasoning applies far treatment B, the potential to produce COs for several more weeks is indicated by the concentration of TPH at the end of 23 weeks as shown in Figure 1. Treatment A was sterilized and was not expected to produce COz, but insufficient sterilization and/or contamination of the treatment resulted in COz production for all sterilized replicates. Though treatment A had the same concentration of TPH as treatment B, [he COZ production in treatment A was much less than in treatment B as can be seen from Figure 2. This may be due to the sterilization of treatment A, which reduced the microbial activity in the soil. In Figure 2, COz produced by independent replicates of treatment A for a period of 23 weeks was less than the COZ produced by replicates for a period of 13 weeks. This may result from differences in the degree of sterilization and contamination of treatment A replicates. The largest losses of carbon were associated with treatment A. There may be some loss because of the sterilization process. Treatment E produced slightly higher quantities of COz than that produced by treatment F (control) as shown in Figure 2. This is the only evidence for the biodegradation of PAM. The carbon dioxide produced by PAM is low compared to that produced by TPH. Biodegradation of PAM is expected to be slow and may take several years. Conclusions Some potential formulations of ATM material are composed of polyacrylamide, petroleum hydrocarbons and residual acrylamide that has not been removed. Biodegradation of polyacrylamide is a slow process and usually takes several years. Polyacrylamide has been shown to be nontoxic to humans, animals, fish and plants, but any residual acrylamide monomer content in PAM products is a neurotoxin to humans and is a major concern in regulation of this polymer. [t is concluded that PAM itself, does not pose any environmental threat, and can be used in various applications such as those described in this work and to treat soils to effectively reduce irrigation-induced erosion. Significant disappearance of petroleum hydrocazbons, of the range Cio - C,4, in an open environment is due to volatilization. Hydrocarbons on the surface of soil and other surfaces are