A. Eschenbach et al., FATE AND STABILITY OF NONEXTRACTABLE RESIDUES OF [C-14]PAH IN CONTAMINATED SOILS UNDER ENVIRONMENTAL-STRESS CONDITIONS, Environmental science & technology, 32(17), 1998, pp. 2585-2590
It has been recognized during recent years that polycyclic aromatic hy
drocarbons (PAH) may form nonextractable residues in soil and that thi
s process may be stimulated by microbial activities. To use that proce
ss intentionally for soil bioremediation, one must ensure that the for
med nonextractable PAH residues will not be released from the soil on
the long run. The long-term stability of four different nonextractable
[C-14]PAH residues ([C-14]naphthalene, [C-14]anthracene, [C-14]pyrene
, and [C-14]benzo[a]pyrene) was therefore monitored under different ec
ological stress conditions, it was found that a considerable fraction
of the total [C-14]PAH residues could be released as (CO2)-C-14 from t
he soil being partly due to a biogenic reduction of the nonextractable
C-14 residue fraction. The turnover of this fraction was comparable t
o the natural turnover rate for humic substances. Neither the addition
of humus-degrading microorganisms nor a mechanical stress treatment o
f the soil structure by freezing and thawing led to a mobilization of
the nonextractable [C-14]PAH residues. However, a significant mobiliza
tion of the nonextractable C-14 activity occurred when EDTA was added
to the soil. The metal-organic soil complexes were destabilized by thi
s complexing agent and released C-14 activity that was attached to col
loidal or dissolved organic matter.