53%. 87 days after the injection the contaminants concentrations were below 16% of
their initial value. 147 days after the injection MCB and B concentration rose again
to 37% and 83% of their initial concentration, respectively, while T almost
disappeared.
19.3.2.3 Microbial Biomass
In the case of the water samples, the PLFA concentrations remained more or less
stagnant. In the case of the soil from the in situ microcosms, a gradual increase of
bacterial biomass was observed to reach their maxima 87 days after the injection.
At this time, approximately ten times higher abundance of bacterial biomass
compared with the initial values was observed. 147 days after the injection the
bacterial biomass was still almost two times higher compared with the initial
values.
19.3.3 Gelatinous Hydrogen Peroxide
The initial concentrations of the contaminants in the respective monitoring well just
few hours before the start of the injections were as follows—B 6.7 μg/L; T 41.3 μg/
L; MCB 451 μg/L. The course of the monitored parameters during the field study is
shown in the graphs below (Fig. 19.5). Although pure hydrogen peroxide gel did not
penetrate into the monitoring well, low H 2 O 2 concentrations were detectable in the
well (up to 0.5 mg/L) 21 days after the injection.
19.3.3.1 Physicochemical Parameters During the Remediation Pilot Test
H 2 O 2 gel injection caused very slight increase in the pH a day after the injection.
Later on, it was more or less stagnant. On the other hand, the effect on the E h was
significant as it increased from À45 mV to +166 mV per day. Later on, it gradually
decreased to levels around 0 mV 147 days after the injection. The O 2 concentration
rose to 2.2 mg/L one day after the injection and decreased quickly to the original
background values after 21 days. The groundwater temperature (data not shown)
rose 1 day after the injection to +3.7
C and remained elevated even 10 days after the
injection. Afterward, the temperature decreased gradually. No significant effect of
the injection on the conductivity (data not shown) was observed.
19.3.3.2 Contaminant Concentrations Throughout the Test
Unlike the case of the solid oxygen sources, injection contaminants concentration
decreased 21 days after the injection. We assume the contaminant mobilization
420
O. Lhotský
their initial value. 147 days after the injection MCB and B concentration rose again
to 37% and 83% of their initial concentration, respectively, while T almost
disappeared.
19.3.2.3 Microbial Biomass
In the case of the water samples, the PLFA concentrations remained more or less
stagnant. In the case of the soil from the in situ microcosms, a gradual increase of
bacterial biomass was observed to reach their maxima 87 days after the injection.
At this time, approximately ten times higher abundance of bacterial biomass
compared with the initial values was observed. 147 days after the injection the
bacterial biomass was still almost two times higher compared with the initial
values.
19.3.3 Gelatinous Hydrogen Peroxide
The initial concentrations of the contaminants in the respective monitoring well just
few hours before the start of the injections were as follows—B 6.7 μg/L; T 41.3 μg/
L; MCB 451 μg/L. The course of the monitored parameters during the field study is
shown in the graphs below (Fig. 19.5). Although pure hydrogen peroxide gel did not
penetrate into the monitoring well, low H 2 O 2 concentrations were detectable in the
well (up to 0.5 mg/L) 21 days after the injection.
19.3.3.1 Physicochemical Parameters During the Remediation Pilot Test
H 2 O 2 gel injection caused very slight increase in the pH a day after the injection.
Later on, it was more or less stagnant. On the other hand, the effect on the E h was
significant as it increased from À45 mV to +166 mV per day. Later on, it gradually
decreased to levels around 0 mV 147 days after the injection. The O 2 concentration
rose to 2.2 mg/L one day after the injection and decreased quickly to the original
background values after 21 days. The groundwater temperature (data not shown)
rose 1 day after the injection to +3.7
C and remained elevated even 10 days after the
injection. Afterward, the temperature decreased gradually. No significant effect of
the injection on the conductivity (data not shown) was observed.
19.3.3.2 Contaminant Concentrations Throughout the Test
Unlike the case of the solid oxygen sources, injection contaminants concentration
decreased 21 days after the injection. We assume the contaminant mobilization
420
O. Lhotský