The sorption-desorption behavior and long-term fate of hexahydro-1,3,5-trin
itro-1,3,5-triazine (RDX) was examined in sterilized and-nonsterilized tops
oil. Results of this study indicate that although RDX is not extensively so
rbed by;the topsoil (K-d(S) of 0.83 L/kg), sorption is nearly irreversible.
Furthermore, there was no difference in the sorption behavior far sterile
and nonsterile topsoil. However, over the long-term, RDX completely disappe
ared within 5 weeks in nonsterile topsoil, and hexahydro-1-nitroso-3,5-dini
tro-1,3,5-triazine (MNX), hexahydro-1,3-dinitroso-5-nitro-1,3,5-triazine (D
NX), and hexahydro-1,3,5-trinitroso-1,3,5-triazine (TNX) metabolites formed
in the aqueous phase. Dyer I the same period, recovery of RDX from sterile
topsoil was high (55-99%), and the nitroso metabolites were not detected.
Only traces of RDX were mineralized to CO2 and N2O by the indigenous microo
rganisms in nonsterile topsoil. Of the RDX that was mineralized to N2O, one
N originated from the ring and the other from the nitro group substituent
as determined using N-15 ring-labeled RDX. However, N2O from RDX represente
d only 3% of the total N2O that formed from the process of nitrification/ d
enitrification.