Effects Of Chemical And Biological Oil Spill Dispersants On Oil Degradation And Microorganism

In recent years,marine oil pollution has occurred frequently in the world.The addition of dispersants is a universal emergency response measure.It is generally believed that dispersants can improve the bioavailability of oil and thus promote the oil biodegradation.At the same time,researchers have debated whether dispersants enhance,inhibit or have no significant effect on oil biodegradation.But in China,the dispersant has not been systematically studied on oil biodegradation.In laboratory experiments,we simulated oil pollution of Zhoushan port and Shenzhen bay and use the 16 S r RNA Illumina Miseq sequencing,GC-MS analysis,and 14C-Naphthalene,14 CHexdecane radioactive isotope tracer technology to explore the effects of different chemical and biological dispersants on the microbial community structure and the influence on oil degradation.The main conclusions are as follows:1.The effects of different chemical and biological dispersants on the biodegradation of oil components in Zhoushan port were studied.These four dispersants all changed the degradation mode of oil.2.The effects of different chemical dispersants(Corexit 9500 and Slickgone NS)and biological dispersants(Rhamnoides and Sophorolipid)on the composition and activity of microbial communities in Zhoushan port were studied.The results showed that different chemical and biological dispersants promoted different dominant microorganisms.Among them,Corexit 9500 promoted the growth of C1-B045 and Alcanivorax and Slickgone NS promoted the growth of Alteromonas and Neptuniibacter.Rhamnolipids and Sophorolipid promoted the growth of Alteromonas and Aesturaiibacter respectively.At the same time,Chemical and biological dispersants reduced the activity of total microorganism and oil-degrading microorganism.3.The effects of different chemicals(Corexit 9500 and JFT)and biological dispersants(rhamnolipid)on the composition of microbial community and oil biodegradation in Shenzhen bay were studied.The results showed that different chemical and biological dispersants promoted different dominant microorganisms.Corexit 9500 and JFT promoted the growth of Neptuniibacter and Oleiphilus respectively,while Rhamnolipids promoted the growth of Aestuariicella.At the same time,all three dispersants promoted the degradation of alkanes and PAHs,and the effect of JFT was slightly better than that of Corexit 9500.4.We compared the effects of oil and its water-soluble fractions on the experimental results.The results showed that different oil addition methods only had effect on the microbial community structure at the early stage,while the effects on the microbial community structure at the later stage of culture tended to be consistent and the dominat oil-degrading bacteria all were C1-B045.At the same time,addition of oil,water-soluble oilfractions and insoluble oilfractions had no effect on the total microbial activity,but in the experiment of addition of oil,the microbial activity of oil degradation was higher than that of direct addition of water-soluble oilfractions.In summary,different types of dispersants and areas are the reasons for disputes over dispersants' effect on the degradation of oil.In summary,the influence of different dispersants on the dominant oil-degrading bacteria and activitiy thus influence the oil biodegradation.Therefore,different dispersants applied in different sea areas have different effects on the oil biodegradation.This study can provide scientific reference for China to formulate bioremediation measures for regional marine oil pollution.