| Nanoparticles(AgNPs)are metallic silver elements with diameter between 1 and 100 nm.AgNPs have stable physical and chemical properties,they show excellent performance in electronics,optics and catalysis,and are widely used in catalyst materials,battery materials,optical materials,antibacterial materials,coatings and so on.However,the widespread use of AgNPs also causes a large number of its entry into the soil environment,which causes a lot of environment problems.Soil enzyme is a kind of protein which has the ability of catalyses,and participates in all soil biochemical reactions.Its activity can characterize the exchange of matter in soil,which can be used as an important index of soil quality evaluation.In this paper,the soil enzyme activity was used as the research object.Under the condition of adding AgNPs,the effects of AgNPs on soil enzyme and the function and potential mechanism of soil enzyme in soil ecosystem were studied.In order to know the ecological repair and pollution removal to provide theoretical basis and technical support,the main contents include the following aspects:For the preparation of AgNPs,this paper focuses on the controllable preparation and explored its formation mechanism.Using ethanol as a reducing agent and solvent,silver nitrate as a silver source,PVP as a covering agent,simultaneously,the effects of different parameters such as reactant concentration ratio,reaction time,reaction temperature and stirring rate on the final morphology and size of AgNPs were discussed.Finally,the size distribution of AgNPs was about 10nm with well dispersity as the material for subsequent testing.The soil urease,dehydrogenase,neutral phosphatase,arylsulfatase and ?-glucosidase activity were studied by soil culture experiment under AgNPs stress,investigated the effects of AgNPs concentration and contact time on soil enzyme activities,AgNO3 control group was used to investigate the migration and toxic mechanism of AgNPs in soil.The results showed that the effects of different concentrations of AgNPs on soil enzyme activities were different.The effect of AgNPs on soil dehydrogenase showed a significant dose effect.With the increase of AgNPs concentration in soil,the degree of soil dehydrogenase was inhibited,and AgN03 was similar.AgN03 inhibitory effect is more obvious at high concentration.Urease activity was not significantly changed under low concentration of AgNPs,and even a certain stimulating effect.High concentration of AgNPs had a strong inhibitory effect on soil urease activity.The inhibitory effect of urease activity in AgNO3 control group was also significant and continued to decrease during the culture.The activity of neutral phosphatase was less inhibited under the stress of AgNPs.Under 1?g/g and 10?g/g AgNPs,the activity of enzyme was only slightly fluctuated.AgNO3 control group had a greater inhibitory effect on neutral phosphatase activity,the degree of inhibition more than 20%at 10?g/g,and more than 50%at 100?g/g AgNO3.The activity of aryl sulfatase was inhibited under the stress of AgNPs,but gradually restored with the increase of the contact time,the dose effect was not obvious.AgNO3 control group is similar,but the degree of inhibition is slightly larger.1?g/g and 10?g/g AgNPs had a excitation to ?-glucosidase activity,100?g/g AgNPs significantly inhibited enzyme activity,and AgN03(1,10,100?g/g)significantly inhibited soil P-glucoside Enzyme activity.In vertical flow constructed wetland plant experiment,the changes of soil enzyme activity in the rhizosphere soil of the wetland system under AgNPs stress were explored.And the effect of wetland plants on AgNPs stress was analyzed bycomparative test.The results shows that the soil enzyme in wetland has obvious seasonal variation,which was significantly correlated with the growth and development of the plant.It was found that the change of soil enzyme in the plant group was obviously smaller,and the plant played a significant buffer effect in the constructed wetland by comparison. |
PDF Full Text Request