Effect Of Nanomaterials On The Inhibition Of Allelochemicals On Algae

Eutrophication is one of the most prominent ecological environmental problems in China.Due to the rapid development of social economy and the irrational utilization of freshwater lakes,the natural biodiversity of a large number of freshwater water bodies in China has been damaged.Cyanobacteria outbreaks are common in many small and medium-sized water bodies,including artificial lakes in cities,which worsen water quality,reduce biodiversity and affect industrial and agricultural production and human health.To curb and harness the eutrophication,the ecological method that are consistent with sustainable development mainly uses the allelochemicals secreted by aquatic plants for remove algal.Using allelochemicals secreted by aquatic plants to remove algae is not only ecologically friendly and sustainable,but also can beautify the environment by planting aquatic plants reasonably.However,with the rapid development of nanotechnology,the application of nanomaterials is becoming more and more extensive.Whereas,their effects on interspecific interactions are rarely reported,especially in aquatic ecosystems.Therefore,the effects of two kinds of nano-materials?nano-fumed silica,NFS;and magnetic Fe₃O₄ nanoparticles,magnetic n-Fe₃O₄?on the algal inhibition effect of allelochemicals on p-hydroxybenzoic acid?p-Ha?were studied,to evaluate how nanomaterials affect the interaction between aquatic plants and algal.The main findings are as follows:?1?In this paper,the effects of magnetic n-Fe₃O₄,NFS and allelopathy p-Ha alone on the physiological indexes of Microcystis aeruginosa?M.aeruginosa?were studied.The results showed that p-Ha>magnetic n-Fe₃O₄>NFS were found in the inhibition rate of M.aeruginosa.The half inhibitory concentration of p-Ha on M.aeruginosa is at the level of 0.716mmol/L.The Minimum Inhibitory Concentration of NFS on the growth of M.aeruginosa?Minimum Inhibitory Concentration,MIC?is at 800mg/L.The effect of magnetic n-Fe₃O₄ on the growth of M.aeruginosa MIC is at182mg/L.It was also found that,the Electric Conductivity?EC?value,the content of superoxide anion(O₂^·—),Microcystins?MCs?,polysaccharides?PS?,and the content of nitric oxide?NO?of M.aeruginosa increased with the p-Ha,magnetic n-Fe₃O₄ and NFS concentration increase.Chlorophyll a content and algal protein content decreased with the increase of p-Ha,magnetic n-Fe₃O₄ and NFS concentration,indicating that M.aeruginosa was strongly inhibited,affecting its growth and related physiological and biochemical indexes.?2?The effects of magnetic n-Fe₃O₄ and NFS combined with allelochemicals p-Ha on the growth and physiological and biochemical indexes of M.aeruginosa were also studied.The results showed that the combination of NFS and p-Ha could attenuate the allelopathic effect of p-Ha,while magnetic n-Fe₃O₄ could enhance the allelopathic effect of p-Ha on M.aeruginosa.The combination of NFS and p-Ha showed that p-Ha could significantly attenuate the allelopathic effect of p-Ha on M.aeruginosa.On the seventh day of the experimental group,the inhibitory rates of each mixed group on M.aeruginosa were-11.3,-30.90%,-0.08%,-7.25%,69.48%,81.66%,that is,when the concentration of p-Ha was in 1.0mmol/L,the inhibition rate on M.aeruginosa was found.At this time,the half inhibitory concentration(IC₅₀)of p-Ha on M.aeruginosa at 7th day in mixed group was 1.021mmol/L.The interaction of magnetic n-Fe₃O₄ and p-Ha showed that n-Fe₃O₄ significantly enhanced the allelopathic inhibitory effect of p-Ha on M.aeruginosa.The inhibition rate of the combined effect on M.aeruginosa was-1.63%-98.2%.The half inhibitory concentration(IC₅₀)of p-Ha on M.aeruginosa was 0.629 mmol/L at 7th day in the mixed group.