Figure 3: PCA biplot showing the factor loadings and the factor scores from the microbial degradation of gasoline on residential soil over 30 days. Variable abbreviations are as shown in Table 2. Soil samples are designated as “F” for Fall, the number of days of degradation and the replicate number (e.g., F-4-1 is the first replicate from a sample aged four days on Fall soil). Note that the observations begin in the upper right quadrant and progress to the lower right quadrant over the course of 30 days.