Effect Of Biochar And Typical Nanoparticles On The Growth Of Green Algae Chlorella Pyrenoidosa

In recent years,because of unique physical and chemical properties,biochar has been more and more widely used in the remediation of soil and water.Biochar also has a combined impact with other nanoparticles on environmental organisms.Therefore,it is of great significance to discuss the influence of biochar on algal cells.To explore the effect of biochar and its influence on the toxicity of other nanoparticles,a series of experiments were carried out in this study.By studying the effects of biochars prepared at two different temperatures on the growth of Chlorella vulgaris,it was found that biochar prepared at 400? showed obvious inhibition on the growth of Chlorella vulgaris,while biochar prepared at 500? showed obvious promotion on the growth of Chlorella vulgaris.Through toxicity index test,it was found that biochar affected the growth of algae by destroying the integrity of cell membrane,producing oxidative stress and affecting the synthesis of chlorophyll a.By measuring inorganic phosphorus and dialysis experiments,we found that the reason is that compared with biochar prepared at 500?,biochar prepared at 400?contains more small molecular organic matter,while inorganic phosphorus content is relatively less.It is also confirmed that inorganic phosphorus can promote algal growth,and small molecular organic matter is an important reason for the biotoxicity of biochar.It was found that the combined toxicity of biochar with nano-plastics or silver nanoparticles was smaller than the toxicity of nanoplastics or silver nanoparticles alone on Chlorella vulgaris.The reasons were as follows: 1)Due to electrostatic interaction and mutual adsorption,nanoplastics or/and silver nanoparticles could not easily contact with algae.2)In the competitive adsorption of Chlorella vulgaris,biochar is in a dominant position,so that nanoplastics or/and silver nanoparticles can no longer contact algal cells and enter algal cells.In conclusion,biochar was toxic in environment,and it has obvious mitigation effect on the toxicity of other toxic nanoparticles,which is of great significance for the safety of biochar and the research on the biotoxicity mitigation methods of other nanoparticles.