Effects Of Carbon Nanotubes' Toxicity On Growth And Physiological Charactericts Of Microcystis Aeruginosa

Since the beginning of the 21st century,a large number of research scholars published articles on global top journals such as "natural" "science" and so on,which stressed the importance of exploring environmental toxicity of nano-materials particles,and appealed to focus on the research on environmental behavior and ecological risk of nanoparticles,with the development and utilization of nanotechnology at the same time.When nanomaterials exposed to environment.it is inevitable to put an unpredictable impact on surrounding organisms,even the ecosystems.What's more,The phenomenon of eutrophication has become increasingly serious,and the outbreak of the "water boom" and"red tide" also has become increasingly frequent under the influence of social development and human activities,the ecological environment problems and the algae control problems arising from the algae have been praised by the worldwide scholars' attention.This paper takes Microcystis aeruginosa,the featured algae in the breakout of cyanobacteria blooms as the tested material.It studies and evaluates the biotoxicity and mechanism of toxication of single-walled carbon nanotubes(SWCNTs)and multy-walled carbon nanotubes(MWCNTs),under their individual or combined effect,to microcystis aeruginosa.It aims to provide a more scientific and comprehensive data support for assessing the safety of algae in aquatic environments and assessing its toxicological effects on organisms.It provides a reference for comprehensively reflecting the risk of ecological exposure of the coexistence of multiple nanomaterials in a real water environment and lays a scientific theoretical basis for the guiding the future use of carbon nanomaterials to control cyanobacteria blooms.The main results are as follows:Low concentration(0.10 mg/L and 0.50 mg/L)of SWCNTS and MWCNTs had a certain stimulating effect on the growth of Microcystis aeruginosa.At high concentrations(50 mg/L and 100 mg/L),CNTs could strongly inhibited cyanobacteria growth and inhibition even was above more than 90%.SWCNTs,EC50 values of each SWCNTs,MWCNTs and their combined effects was 28.367 mg/L,68.664 mg/L and 12.011 mg/L,respectively.Joint toxicity is determined at synergistic,which is higher than single toxicity.Besides,SWCNTs are more toxic than MWCNTs.In the range of low concentration(0.10 mg/L-10.00 mg/L),CNTs promoted the synthesis of photosynthetic pigments and promoted the increase of algal cells.The content of carotenoid decreased gradually with the increase of CNTs concentration.High concentration of CNTs will seriously inhibit the synthesis of three kinds of photosynthetic pigments,algae cell viability decreased.In general,MWCNTs results are little higher than SWCNTs.Single toxicity test results were higher than the combined toxicity test.The activity of SOD and POD were influenced with the trend of increase at initial,then decreased afterwards.Instead,the joint toxicity test showed a contradictory tendency that is decrease at first,then decrease.CAT activity decreased with the increase of CNTs concentration,while the content of MDA increased gradually.Among them,the variation range of MWCNTs is the smallest.When the concentration was higher than 10.00 mg/L,the activity of all antioxidant enzymes was significantly inhibited,and the accumulation of MDA was serious.The content of soluble protein decreased initially with the CNTs concentration variation,and then decreased,which also has a correlation to phycocyanin.While soluble sugar content changing tends was in contrary to the protein content.Low CNTs concentrations could stimulate the protein content rising.At 5.00 mg/L,protein content reached the peak.At high concentrations(50 mg/L-100 mg/L),protein synthesis was severely blocked.In addition,1.00 mg/L is the changing spot concentration of soluble sugar.