Biofilms are believed to play a significant role in the fate
and transport of contaminants in aquatic environments.
However little is known about the rates of sorption (k) and
partitioning (K
d) of contaminants to biofilms. Studies of
the latter were performed using mature biofilm cultivated
in a roto-torque reactor. The reactor was flushed with
river water containing a mixture of tetrabutyltin, p,p-DDT,
diclofop-methyl, triallate, lindane, atrazine, parathion-methyl, and dimethoate in two experiments. The first
experiment was conducted at a spiked level of 1 μg/L, and
the second was conducted at 10 μg/L for each component.
Apart from dimethoate, there was rapid depletion of all
contaminants from the water phase within the first 5−10
min with sorption occurring by pseudo-first-order kinetics.
In general, the mean values of k (10-4 min-1) increased
with water solubility and were 8, 70, 110, 180, 230, 370, and
100 for p,p-DDT, diclofop-methyl, triallate, tetrabutyltin,
lindane, atrazine, and parathion-methyl, respectively. The
values of log K
d increased linearly with log K
ow and
decreased linearly with the log of the aqueous solubilities.
In general, K
ow values were significantly greater than
the corresponding values of K
d, indicating that partitioning
of contaminants was not limited to lipophilic regions of
the biofilm.
