ESTCP Project #1011, Rhizosphere
Final Report
Table 4. Table of P values for ANOVA of decalin GDD normalized data for three ESTCP sites,
P≤ .20 are bold.
One way
Factorial ANOVA
ANOVA
Fert X Plant
Plant
Fertilizer
TPH
.336
.934
.699
.075
Σ-PAH
.369
.316
.161
.847
Aliphatic C8-10
.734
.322
.868
.625
Aliphatic C>10-12
.773
.981
.512
.414
Aliphatic C>12-16
.640
.469
.477
.442
Aliphatic C>16-35
.343
.746
.953
.078
Aliphatic C8-35
.399
.950
.746
.100
Aromatic C8-10
.730
.949
.346
.567
Aromatic C>10-12
.329
.313
.146
.063
Aromatic C>12-16
.525
.778
.376
.242
Aromatic C>16-21
.396
.822
.758
.095
Aromatic C>21-35
.249
.855
.801
.048
Aromatic C8-35
.212
.977
.901
.036
Plant Effects on Depletion of Specific Petroleum Fractions. We observed significant
(P=0.075) plant-treatment effects for TPH but not the summed PAHs (Table 4 and Figure 28).
The heavier aliphatic fractions, C>16-35 aliphatics, and consequently, the C8-35 aliphatics were
significantly different than the treatments without plants, but the other aliphatic fractions did not
show an effect (Figure 29). Additionally, there were significant (P<0.10) plant effects for the
C>16-21 and C>21-35 aromatic fractions and consequently, the C8-35 aromatic total, but lighter
aromatic fractions did not show an effect (Figure 30). For clarity, only those aromatic fractions
showing significant plant effects are also shown (Figure 31). Beneficial plant effects have been
observed for heaver, more recalcitrant fractions in other studies on petroleum degradation
(Reynolds et al., 2001) and in other recalcitrant compounds such as polychlorinated biphenyls
(PCBs) (Leigh et al., 2002). The hypothesized mechanism for this is analogue enrichment
provided by compounds released from the plant. These data are in agreement with results we
have obtained in laboratory-growth chamber studies (Reynolds et al., 1997; Reynolds et al.,
1998).
Fertilizer Effects on Depletion of Specific Petroleum Fractions. All fertilizer main effects
comparisons are shown for TPH and summed PAHs, aliphatic fractions, and aromatic fractions
in Figures 32 through 34, respectively. Fertilizer had no effect with P<0.20 (Table 4) except for
the aromatic C>10-12, which showed a significant effect (P=0.063). Data for fertilizer effects on
the aromatic C>10-12 fraction are shown in Figure 35. The variability in the fertilized treatments
was large, yet fertilization resulted in lower degradation (P=0.063) of the aromatic C>10-12
fraction than the non-fertilized treatments.
Inhibition due to fertilizer is counter-intuitive, yet it agrees with the general observations from
two demonstrations we conducted in Korea. These data suggest that fertilizer alone can inhibit
29
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