glass cylinders (15cm height£4.5cm internal
diameter) contained 160gdw of soil over a 2cm high layer of glass beads (2mm diameter) supported by a fine Teflon mesh (to allow
the collection of leachates in future experiments). Soil was spiked
with aqueous suspensions of Atrazerba FL in order to obtain doses
equivalent to 40 and 400Lha¡1
, and the whole soil volume was
homogeneized with a glass rod to promote incorporation of atrazine.
Two sets of bioaugmentation treatments were performed, as
follows: (i) one single inoculation with the P. ADP cell suspension
to give approximate inoculum densities of 107 or 108CFUg¡1 at the
beginning of the experiment, and (ii) three successive inoculations
(»3.5£107CFUg¡1 each) at days 0, 2 and 4 (for 200£ RD contaminated
soils only). For biostimulation treatments, trisodium citrate
was added to give 0.8 and 2.4mgg¡1 of soil when distributed.
Non-inoculated and/or non-amended controls were also included
in each set of experiments. Soil moisture was adjusted to 40% of
the soil WHC as described above. Amended soils were again mixed
thoroughly and gently packed into the glass cylinders. Microcosms
were incubated at 25°C in the dark (to avoid atrazine photodegradation)
and weighted every day in order to replace the water lost
by evaporation. Samples of soil were periodically collected and
processed immediately or stored at ¡20°C for microbiological or
chemical analysis, respectively