Figure 5

POD specific activities in earthworms. Control represents treatments without the addition of B[a]P, one-time addition are treatments with the addition of B[a]P at one time, multiple-time addition are treatments with the addition of B[a]P by twelve times. Error bars represent standard deviations. Samples with a common upper-case letter indicate no significant difference among different incubation times under the same treatment (P > 0.05, n = 3), and those with a common lower-case letter indicate no significant difference among different treatments at the same incubation time (P > 0.05, n = 3).