Wg. Macintyre et al., DEGRADATION KINETICS OF AROMATIC ORGANIC SOLUTES INTRODUCED INTO A HETEROGENEOUS AQUIFER, Water resources research, 29(12), 1993, pp. 4045-4051
Degradation rates of benzene, p-xylene, naphthalene, and o-dichloroben
zene have been measured in a heterogeneous, unconfined aquifer during
a pulse injection experiment at Columbus Air Force Base, Columbus, Mis
sissippi. Dissolved oxygen in the pulse plume maintained aerobic condi
tions. Degradation kinetics calculated from the complete field data se
t were approximately first order with the following rate constants: be
nzene, 0.0070 d-1; p-xylene, 0.0107 d-1; naphthalene, 0.0064 d-1; and
o-dichlorobenzene, 0.0046 d-1. Reaction rates were also calculated fro
m a near-field subset of the data using a model based on the hydrologi
c characteristics of the aquifer. Shapes of the degradation rate curve
s were consistent with microbial degradation processes. Maximum degrad
ation rates obtained are presumed to be characteristic of the microbia
l population metabolism. Carbon 14-labeled p-xylene was included in th
e injection solution to permit detection of degradation products. This
technique is suggested for future field experiments, because it disti
nguishes solute degradation from solute losses by sorption and evapora
tion and allows mass balance to be demonstrated throughout the course
of the reaction in the aquifer.