Parameter-based models estimating microbial hydrocarbon-degrading activity in a diesel-contaminated soil

Bioremediation is a popular method to degrade diesel from soil. Bioremediation strategies can be developed by estimating the effect of important environmental parameters on microbial activity. Respirometry was used to develop empirical models describing the effect of temperature, moisture, nitrogen, phosphorus, and NaCl concentration on microbial activity in a diesel-contaminated soil from Wyoming. Treatments were conducted by varying one parameter while holding others constant for each parameter tested. Carbon dioxide (CO2) data was analyzed using a base equation where its coefficient values were functions of each parameter. Two physiologically different groups of microorganisms were suggested by the results yielded by the analysis of CO2 data collected while varying temperature. The empirical models were combined into one model and this model was tested against soils from Egypt and California. No significant difference was observed between predicted and actual CO 2 data from the Egypt soil, but significant differences were observed between predicted and actual CO2 data from the California soil. This suggests that the empirical models are limited to soils from semi-arid to arid regions. Overall, this study demonstrates empirical models from respirometric data provide a method to describe microbial activity in diesel-contaminated soils.