Comparative Study On The Effect Of Three Typical Nanoparticles On Soil Bacterial And Enzymes Activities

Among varied kinds of nanoparticles,Ag nanoparticles,Zn O nanoparticles and fullerene nanoparticles are the most representative nanoparticles in most use.Plenty of nanoparticles can leach to the environment through manufacture,employment and deposition process.Soil is the main container in ecological environment for nanoparticles,soil microbial is one of the most diverse populations,soil enzymes are of great importance to circulation of materials,both soil microbial and enzymes are sensitive indicators of pedoturbation,thus,studies of nanoparticles influencing to soil microbial and enzymes are of great importance.This studies put three kinds of typical nanoparticles(Ag NPs representing metal nanoparticle,Zn O NPs representing metal oxide nanoparticle,n C60 representing carbon base nanoparticle)into soil(Corresponding soluble ions and derivative are set as experiment control),being exposed to different concentrations(0?1?10?100?g/g)after different period of time(0?1?3?6?10?15 days).Three kinds of soil enzyme activities(dehydrogenase,urease,phosphatase)had been measured to investigate the influence mechanisms of nanoparticles to soil enzyme activities.The result showed that silver nanoparticles and silver ion have an obvious influence on enzyme activities and presented a significant correlation to exposure concentrations.Both silver nanoparticles and silver ion of middle and high concentration(10?100?g/g)can significantly inhibit soil dehydrogenase and urease activity.Silver ion posed a greater and a more acute impact.Silver nanoparticles of low concentration had a slight stimulation while silver ion of low concentration posed a slight inhibition.Silver nanoparticles of high concentration posed a slight inhibition effect,but silver ion of high concentration posed a significant inhibition.Zn O nanoparticles and C60 nanoparticles had no significant effects on these three enzyme activities,while zinc ions and fullerenols had a little impact on soil enzyme activities.The impact of three typical nanoparticles on soil microbial under different expose concentrations for different period had been investigated.As a result,in order of most inhibit,it goes: Ag NPs>Zn O>n C60.High through-put sequencing had been conducted under different treatments(before dosing D.0,3 days after dosing D.3.CK,D.3.Ag NPs,D.3.Zn ONPs,D.3.n C60,15 days after dosing D.15.CK,D.15.Ag NPs,D.15.Zn ONPs,D.15.n C60),the order of soil bacterial community diversity is D.0>D.3.CK?>D.15.Zn ONPs?>D.3.n C60?>D.15.n C60?>D.15.CK?> D.3.Zn ONPs>D.3.Ag NPs>D.15.Ag NPs.It has been found by analyzing soil microbial community structure that the greatest changes occur in silver nanoparticles treatment group,Proteobacteria and Bacteroidete were coming to the dominant species gradually when other phylums decreasing.Compared with control group,other nanoparticle treatment groups presented significant changes.Both anaerobic and aerobic bacteria have a certain resistance to the environment changes,but sensitive to silver nanoparticles,slightly stimulated by zinc oxide nanoparticles.In silver nanoparticle treatment group,gram positive bacterias had a higher resistance than gram negative bacterias.The bacterias concerning nitrogen circulation such as Cupriavidus?Bradyrhizobium?Pseudomonas?Bacillus?Nitrospira are resistant to nanoparticles,for whose relative abundance increased a little under silver nanoparticle stress.It has been found by analyzing differences between different treatments that the main reasons influencing soil bacteria community are cultivate time and the types of nanoparticles.Only silver nanoparticle treatment shows a significant difference with the control group,and a significant difference can be also found between samples from different cultivate time.As for other treatment groups,the number of distinctive bacteria genus had increased through the incubation time.