Study On The Phytoremediation Of Petroleum-contaminated Soil

Due to the petroleum production and application expanding,the soil pollution by petroleum becomes a serious environmental problem,and it has been attracting considerable public attention over last decade.Because the phytoremediation is effective without second pollution,non-intrusive,inexpensive comparing with traditional physicochemical treatment methods,specifically it could be used in pollution filed,the phytoremediation is becoming a key aspect for soil petroleum-polluted control in future.In this paper,the phytoremediation of petroleum-contaminated soil was studied from two aspects:screening the most promising plants for phytoremediation on high efficiency degradation of petrol hydrocarbon,and evaluating the effect of phyto- active sludge remediation of petroleum-contaminated soil.The main results are as follows:(1)Petroleum contamination had no effect on germination of Faba Linn..,Glycine max(L.)Merr.,Vigna sesquipedalis Koern.,Glycine max Merr.,Phaseolus calcaratus Roxb.,Lolium multiflorum Lam.,but the germination of Zea mays L. was inhibited in the high concentration polluted treatments,and at initial concentration of 10000mg/kg,the generation rate was 65%,which was 100%in the unpolluted treatment.The above-ground portion and root growth of Glycine max(L.)Merr.and Vigna sesquipedalis Koern were little affected when compared to the uncontaminated control at initial concentration of 1000-7000 mg/kg,and only in 10000 mg/kg petroleum-contaminated treatment,the plant heights and biomasses of the two plants showed significant reduction.After a growth season,the growth of Phaseolus calcaratus Roxb.,Lolium multiflorum Lam.were seriously inhibited in contaminated soil,and in the treatment of 10000 mg/kg oil pollution,the reduced biomass reached 78.9%and 88.8%of uncontaminated control.Although the above-ground portion of Zea mays L.was obviously inhibited due to crude oil but the root/shoot ratio was increased in the contaminated soil,and root growth showed less affected compared to shoot, so Zea mays L.Showed potential ability for phytoremediation.Among the seven plants, Faba Linn..has the highest tolerance in the petroleum-contaminated soil.(2)At initial concentration of 1000 mg/kg,4000 mg/kg,plants had no effect on degradation of petroleum,soil planted Faba Linn..,Phaseolus calcaratus Roxb., Zea mays L.showed higher degradation rate than other plants,and Zea mays L. was the most effective plant on phytoremediation to petroleum-contaminated soil, the degradation rate of petroleum were 50.37%,49.05%in 7000 mg/kg,10000 mg/kg petroleum-contaminated soil,the effect of Phaseolus calcaratus Roxb. was followed,and in the treatment of Phaseolus calcaratus Roxb.,the degradation rate of petroleum were 49.61%,44.82%.So Phaseolus calcaratus Roxb.and Zea mays L.were promising species for phytoremediation of petroleum-contaminated soils.Degradation ability of six plants(except Lolium multiflorum Lam.)differs in different vegetal periods,maximum degradation rate occurred in the period of seeding.(3)There was less restraints to the generation of plants in sludge treatment than un-sludge treatment.And in the earlier stage,the shoot of Faba Linn.was obviously developed in the sludge treatment than Zea mays L.,and the effect of sludge was reduced in the later time.The interesting results was found that the biomass of two plants was higher and the inhibition of root was less in the 8ml/pot sludge treatment than 20ml/pot sludge treatment.(4)Phyto-active sludge remediation accounts little for the dissipation of petroleum. The primary concentration of petrol hydrocarbon was rapidly reduced after the addition of sludge,but during the experiment,the addition of sludge didn't promote the biodegradation of petrol hydrocarbon.However,massive organic matter and nutrition substance such as Nitrogen,Phosphorus and potassium were in sludge,which also can be used as fertilizer to apply plants and microbial enough nutrition.Furthermore,increased biomass of plants and microbial activity may accelerate the efficiency of phyto- active sludge remediation.