Ecological Remediation Of Oil-contaminated Wetland By Indigenous Oil-degrading Microorganisms And Native Plants On Huangpu River Shore

As a main water transport channel of Shanghai, the ecological environment of Huangpu River shore wetland is being damaged more and more seriously due to the oil spills. This study aims at the Huangpu River shore wetland, the combined effect of oil-degradaing microorganisms and plants was used to repaire oil-polluted wetland. The sediments of study area have a high oil content, the average value was 512mg/kg, the peak value was 1708mg/kg. Experimental results indicated that there are significant differences between the rhizosphere and non-rhizosphere soils in the characteristics of microorganism activity and enzyme activities. It concluded that the plant roots could promote the enzyme activities and microorganism activity, the experimental plants might improve the ability of phytoremediation, contributing to the mineralization, degradation and distribution of oil pollutants.Three oil-degrading bacterial strains (M1, M2 and M3) were discovered and identified by sequencing their 16S rDNA genes, two of them were Pseudomonas and the other one was Alcaligenes. The proper growth conditions of the oil-degraders were 30³5℃, salinity 0¹.0%, pH 7⁷.5. The degradation ratios of three bacterial strains were 33.05%,15.21% and15.89% in 7 days, respectively. They all played a good role on the n-alkanes within the range of C₁₆^C₂₅ components of diesel.The outside simulated experiments were conducted to evaluated the diesel decontaminating potential of the isolated oil-degraders and it co-activition action of four native plant species, including Scirpus tripueter L(STL), Phragmites australis(PA), Carex phacota Spr(CPS) and Sagittaria sagittifolia L(SSL). The inherent microorganisms could adapt and degrade diesel in a low diesel concentrations of 5 000mg/kg. However, the oil-degraders would adapt to a higher concentration, and achieve a better removal efficiency(67.41%) at the 15000 mg·kg^-1 soil. The removal ratios of diesel were 72.62%,68.45%,75.81% and 73.08% (on 15 000 mg/kg soils) respectively under the co-activation action of STL, PA, CPS and SSL with oil-degraders in the 60d experiment. The four plants with oil-degraders could degrade n-alkanes within the range of C₁₂^C₃₀ components.The combined bioremediation of Salix matsudana and oil-degrader M1 was evaluated, the Salix matsudana has an absorption effect of oil and it could enhance soil microbial activity and the activity of various enzymes. Phytoremediation effects of organic pollutants might be influenced by the interactions of plants and microbes in the rhizosphere. The results confirmed that the oil-degraders and the plant improved the biodegradation ability of diesel pollutants. The diesel could inhibit the activity of enzymes in the rhizosphere soils. The microbial populations were significantly larger in the oil-degrader soils and the rhizosphere soils compared to the controls. The oil-degrading bacteria M1 could enhance the bioremediation capacity.The research results showed that the plants could strength the biodegradation of oil-degraders, especially in a higher diesel concentration soil. The strengthening effect is particularly significant.