EFFECTS OF MIXING ADDITION OF THE GREENERY WASTES ON THEIR REMEDIATING EFFECTS ON PETROLEUM POLLUTED SOIL

In this study, greenery wastes of Platycladus orientalis (Po) and the other 5 species which are commonly used in urban landscaping were collected. Monospecific greenery wastes and their 1:1 mixtures containing Po waste were used to treat contaminated soil with a petroleum content of 15.00 g/kg, to conduct a 150-day laboratory remediating experiment at 20-25℃, under a soil moisture of 50% of the saturated water holding capacity. The effects of mixed addition of greenery wastes on their re-mediating effects on contaminated soil were detected, to provide scientific basis for the reasonable utilization of greenery waste in contaminated soil remediation. The results indicated that: (1) Mixed addition of Po waste with Picea asperata (Pa), Acer truncatum (At), Ginkgo biloba (Gb) or Juniperus formosana (Jf) waste significantly enhanced their effect of removing petroleum contaminants, espe-cially for removing aromatic and non-hydrocarbon substances; while the mixed addition of Po waste with Pinus tabuliformis (Pt) waste significantly weakened their remediating effects. The mixed addition of Po waste with Gb or Jf waste significantly enhanced their effects of replenishing soil available N and P; the mixed addition of it with Pa, Pt, Gb or Jf waste tended to enhance their effects of stimulating the activities of soil invertase, urease, phosphatase and dehydrogenase, while the mixed of it with At waste tended to weaken their simulating effects. (2) Mixed litters with high contents of C, N, terpenoids and amino acids, and chemical dispersion facilitated the degradation of petroleum contaminants, while those with high contents of soluble saccharides and total organic acids/terpenoids led to contrast effects; mixed litters with high N content facilitated the increment of soil enzymatic activities, while those with high contents of total organic acids and terpenoids led to contrast effects. In conclusion, mixed addition of Po and Jf, Po and Gb, and Po and Pa wastes might enhance their overall remediating effects on petroleum contaminated soil, while mixed addition of Po and Pt wastes might weaken their ability of removing the contaminants, and this mixing form of greenery wastes should be avoided.