Plant Effects on Depletion of Specific Petroleum Fractions

Performance Assessment - LR-04-190026

Microbial Characterization - LR-04-190028

LR-04-19
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Table 2. Table of P values for ANOVA of decalin GDD normalized data for three ESTCP sites,

.075

.078

.100

.146

.063

.095

.048

.036

4.1.2 Results for Two-Way Factorial ANOVA Comparison of Main Effects of

Fertilizer, Plants, and Their Interactions

Table 2 also lists the P values for the main effects and interactions of the factorial ANOVA,

using all depletion data from the three sites, normalized to decalin and GDD-C. All means and

95% confidence intervals are also shown in Figures 10-13. Data showed no significant

interactions.

4.1.3 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 2 and Figure 10). 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 11). 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 12). For

clarity, only those aromatic fractions showing significant plant effects are also shown in Figure

13. 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).

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