| Polycyelie aromatie hydroearbons because of its stable benzene ring structure, is persistent organic pollutant, insoluble in water. People pay close attention to it, because it can induce cancer, malformation and mutation to human. Simultaneously, it can affect soil structure and quality greatly negatively, so restoration of soil polluted by it has been a global focus. At present, there were many methods to restore soil polluted by (PAHs). But because plant-microbial associated bioremediation is low cost, effective and cannot lead to secondary pollution etc., it has great utilization potentiality. Its rhizoremediation accomplish through plants absorbing PAHs, root exudate and enzyme degrading PAHs and intensifying microorganism, then and microorganism degrading PAHs.The study chose common greening tree species Koelreuteria paniculata at southern as experiment tree specie and chose pyrene as PAHs representative, and made 1 treatment and 2 controls by pot culture:(1) treatment:plants planted in 1000 mg·kg-1 soil polluted by pyrene (2) controls:plants planted in soil not polluted by pyrene, no plants planted in 1000 mg·kg-1 soil polluted by pyrene. And the study research dynamic change of concentration and degradation rate in Koelreuteria paniculata rhizosphere soil and non-rhizosphere soil and dynamic change of soil pH, TOC, TN, TP and DOC and microbial biomass carbon. It was shown that:(1) Koelreuteria paniculata could degrade pyrene effectively. During 270 days’ experiment, degradation rate in rhizosphere soil and non-rhizosphere soil was 88.66% and 74.90% respectively. The degradation rate in rhizosphere soil was increased by 13.76% compared with that of non-rhizosphere. The degradation rate in rhizosphere soil and non-rhizosphere soil was 36.35% and 22.59% respectively in comparison with the control. During 60th ～90th, the degradation rate in rhizosphere soil and non-rhizosphere soil was maximal. Namely, the effect of degradation was great in rhizosphere soil and non-rhizosphere soil in 60th ～90th.(2)Pollution of pyrene made soil pH increase in the scope of acidity. Compared with the control of no pyrene pollution, the soil pH in rhizosphere soil and non-rhizosphere of pyrene pollution was more than that in rhizosphere soil and non-rhizosphere of no pyrene pollution. And there was significant in pH values between rhizosphere soil of pyrene pollution and rhizosphere soil of no pyrene pollution and between non-rhizosphere soil of pyrene pollution and non-rhizosphere soil of no pyrene pollution (P<0.05).Pollution of pyrene made soil the content of TOC increase. The content of TOC in rhizosphere soil and non-rhizosphere of pyrene pollution exceeded that in rhizosphere soil and non-rhizosphere of no pyrene pollution respectively. There existed significance in TOC between rhizosphere soil of pyrene pollution and rhizosphere soil of no pyrene pollution in 0th,15th,30th and 180th and between non-rhizosphere soil of pyrene pollution and non-rhizosphere soil of no pyrene pollution in 30th,60th,180th and 270th (P<0.05).The content of TN in rhizosphere soil of pyrene pollution exceeded that in non-rhizosphere of pyrene pollution and there existed significance in 30th,90th and 270th (P<0.05)th. The content of TN in rhizosphere soil of pyrene pollution is more than that in rhizosphere soil of no pyrene pollution in 30th-270th. The content of TN in non-rhizosphere soil of pyrene pollution exceeded that in non-rhizosphere soil of no pyrene pollution.Pollution of pyrene made soil the content of TP decrease in comparison with that of no pyrene pollution. Namely, the pollution of pyrene made the content of TP in soil decrease. Compared with that in rhizosphere soil of no pyrene pollution, the content of TP in rhizosphere soil of pyrene pollution decreased 35.1% in 0～270th days, and there existed significance in 30th ～270th (P<0.05). Compared with that in non-rhizosphere soil of no pyrene pollution, the content of TP in non-rhizosphere soil of pyrene pollution decreased 28.8%in 0～270th days, and there existed significance in 0th～180th (P<0.05).Pollution of pyrene made soil the content of DOC decrease in comparison with that of no pyrene pollution. Compared with that in rhizosphere soil of no pyrene pollution, the content of DOC in rhizosphere soil of pyrene pollution decreased 8.8% in 0～270th days, and compared with that in non-rhizosphere soil of no pyrene pollution, the content of DOC in non-rhizosphere soil of pyrene pollution decreased 7.2% in 0-270th days. Analysis of variance showed that there existed significance in the content of DOC between rhizosphere soil of pyrene pollution and rhizosphere soil of no pyrene pollution and between non-rhizosphere soil of pyrene pollution and non-rhizosphere soil of no pyrene pollution(P<0.05).Compared with that of no pyrene pollution soil, pollution of pyrene made soil the content of microbial biomass carbon decrease in 0th ～30th days and 180th ～270th, but increased in 60th and 90th, which reflected that the degradation that microorganism degraded pyrene was fastest in 60th and 90th. The content of microbial biomass carbon in rhizosphere soil exceeded that in non-rhizosphere soil. Compared with that in non-rhizosphere soil, the content of microbial biomass carbon in rhizosphere soil exceeded to 17.0% in pyrene pollution soil in 15th ～270th. And the content of microbial biomass carbon in rhizosphere soil exceeded to 26.6% in no pyrene pollution soil in 15th ～270th, in comparison with that in non-rhizosphere soil.(3) Degradation in rhizosphere soil polluted by pyrene was extremely significantly negative relation to DOC and microbial biomass carbon (P<0.01); degradation in non-rhizosphere soil polluted by pyrene was extremely significantly negative relation to DOC (P<0.01), significantly negative relation to microbial biomass carbon and significantly positive relation to soil pH (P<0.05). Degradation in rhizosphere soil polluted by pyrene was no significant relation to soil pH, TOC, TN and TP (P>0.05). Degradation in non-rhizosphere soil polluted by pyrene was no significant relation to TOC, TN and TP (P>0.05), and soil pH was significantly negative relation to DOC and microbial biomass carbon in non-rhizosphere soil (P<0.05).In conclusion, Koelreuteria paniculata had preferable capacity to get rid of pyrene, rhizospheric section> non-rhizospheric section> the control. And in 60th and 90th days, there existed maximal removal efficiency in rhizospheric section and non-rhizospheric section of Koelreuteria paniculata.ln 0～270 days, the pH and the content of TOC in rhizosphere soil and non-rhizosphere soil of pyrene pollution all exceed that in rhizosphere soil and non-rhizosphere soil of no pyrene pollution, while the content of TP, DOC was inferior to that in rhizosphere soil and non-rhizosphere soil of no pyrene pollution. There was not a rule can be followed by the pollution of pyrene impact on TN in soil. In 0～270 days, the pH in rhizosphere soil of pyrene pollution and no pyrene pollution was inferior to that in non-rhizosphere soil, while the content of TOC, TN, TP, DOC and microbial biomass carbon exceeded that in non-rhizosphere soil. |
PDF Full Text Request