Soil Fertility Status and Degradation of Munitions Constituent Contaminated Soil.

Current models for predicting the environmental fate of munition constituents (MC) in soils are solely based on chemical distribution parameters, and neglect the larger considerations with respect to other soil parameters. We propose a new model based on the whole soil activity for predicting the long-term residence time and fate of MC based on agronomic soil fertility concepts. We demonstrate the beginnings of such conceptual development for predicting the environmental fate of MC utilizing classical soil fertility measurements, and quantifying a soil’s potential buffering capacity (PBC) of the essential nutrients N, P, K via the quantity-intensity (Q/I) approach. These relationships are demonstrated by correlating experiments involving full physical and chemical characterization of 8 taxonomically distinct soils, with batch reactor studies determining MC degradation potential. Soils were incubated in a slurry for 10 days in a closed reactor system with temperature, pH, and Eh readings recorded every 24-h. Air and slurry samples were taken 8 times within the incubation period. Carbon dioxide production, TNT and degradation product concentrations in solution and sediment, and solution nutrient concentrations were collected to obtain a full picture of soil chemistry changes due to microbial activity in response to additions of TNT. Running a linear regression of the degradation rate coefficient (K) against the PBC of N and K shows a positive linear relationship with R² values of 0.8402 and 0.7865 respectively, implying that degradation potential can be predicted by PBC of N and K. Regression against PBC P shows less correlation and therefore is less likely to prove to be useful when predicting MC degradation. These studies lay the groundwork for ongoing investigations seeking to enhance predictions of the environmental fate of MC compounds based on freely available soil nutrient data.