| Silver nanoparticles(AgNPs)has been widely used and has strong biological toxicity and bactericidal properties.At present,the presence of AgNPs has been detected in estuaries and coastal waters,but the environmental behavior of AgNPs entering coastal waters and its impact on marine bacteria have not been studied.Salinity increasing and high dissolved organic matter(DOM)are two typical characteristics in area from estuary to nearshore.In order to study the environmental behavior of AgNPs in seawater,this paper studied the stability of different particle sizes(10 nm and 40 nm)AgNPs with the same coating(citrate)and different coating(citrate and bPEI)AgNPs with the same particle size(40 nm)in artificial seawater with different salinity and DOM concentrations.Further,on the basis of AgNPs environmental behavior in seawater,the correlation between AgNPs environmental behavior and its toxicity to typical marine bacteria Roseobacter denitrificans och114 and Vibrio caribbeanicus JL3219 was explored.Finally,the growth inhibition differences of AgNPs on Roseobacter denitrificans och114,Vibrio caribbeanicus JL321 9 and Vibrio sp.JL3 833,Alteromonas macleodii ATCC27 126 and Marinobacter algicola JL117 were studied.The results show that:1.In artificial seawater with different salinity,compared with the salinity of 0,AgNPs have all been reunited,different particle sizes of AgNPs with the same coating(citrate)form agglomerates about 100 μm in all salinity,there was no significant difference in size.When the AgNPs coating is different,AgNPs coated with citrate(Ag-Cit)form agglomerates are 2 to 40 times larger than AgNPs coated with bPEI(Ag-bPEI).It shows that AgNPs will agglomerate in all seawater with different salinity,the size of the agglomerates has no obvious correlation between and the salinity of seawater and the particle size of AgNPs,but has significant correlation with coating of AgNPs.2.In the presence of DOM in seawater,the Ag-Cit agglomerates are 5 to 15 times smaller than Ag-bPEI.DOM enhances the stability of the AgNPs coated with citrate,while reducing the the stability of the AgNPs coated with bPEI.The higher the DOM concentration,the worse the stability of Ag-bPEI.It is indicated that DOM is an important factor affecting the stability of AgNPs,and further indicates that the coating of AgNPs is a key factor affecting its stability in seawater.3.In pure artificial seawater,Ag-Cit formed a larger agglomerate than Ag-bPEI,and corresponding the inhibition rate of Ag-Cit to och114 and JL3219 was significantly weaker than Ag-bPEI(P<0.05).In high concentration DOM seawater,the Ag-Cit agglomerates was significantly smaller than Ag-bPEI,and corresponding the inhibition rate of Ag-Cit to och114 and JL3219 was significantly stronger than that of Ag-bPEI(P<0.05).There was no significant difference in the stability of AgNPs in pure artificial seawater with different salinity,and there was no significant difference in the inhibition rate of AgNPs to och114 and JL3219(P>0.05).It is shown that the toxicity of AgNPs to bacteria under different conditions in seawater environment is related to the stability of AgNPs(degree of agglomeration).Under the condition that AgNPs form larger agglomerates,its toxicity to bacteria is weaker.4.The toxicity of AgNPs to 5 strains marine bacteria from strong to weak was och114,JL117,JL3219,JL3833 and ATCC27126,och114 and JL117 were sensitive species.By studying the mechanism of Ag-Cit10 toxicity to sensitive species och114,AgNPs can significantly increase the permeability of outer membrane and intima of och114 cells.The accumulation of reactive oxygen species(ROS)in och114 cells increases with the concentration of AgNPs.1 mg/L AgNPs stimulated the activity of superoxide dismutase(SOD)in och114 cells significantly.This indicates that AgNPs have physical and physiological damage to och114.AgNPs can damage the cell membrane of bacteria and stimulate the increase of intracellular ROS levels and cause changes in the activity of SOD enzymes related to oxidation levels. |
PDF Full Text Request