Geomorphological Connections to Soil Available Water and Predicting the Environmental Persistence of Munition Constituents.

Traditional degradation experiments to determine environmental persistence of compounds are done using soils that are obtained from the surface and under fully saturated conditions. These experiments provide useful data, however are not fully representative of the soil environment. To better understand environmental persistence this study examined the connections between soil geomorphology and soil available water for the ability to predict environmental persistence of munitions. Degradation experiments for TNT and RDX were conducted using different Alfisol soil horizons and at different soil available water contents. Microbial degradation is hypothesized to be the primary degradation pathway due to the available nitrogen from soluble forms of TNT and RDX. The degradation rate of the munition constituents was determined and preliminary results suggest that microbial activity is greater, as determined via CO2 gas evolution, for soils with munition constituents than for soils without munition constituents. In addition, soil horizons with better fertility status and greater soil available water have increased degradation rates compared to deeper soil horizons that tend to have less soil available water. Degradation products of both TNT and RDX are present shortly after soil spiking further supporting the hypothesis that microbial degradation is the primary pathway impacting the environmental persistence of TNT and RDX.