The Environmental Risk Of Engineered Nanomaterials:examples Of Cu（OH）₂ Nanopesticide And CuS Nanoparticles

With the rapid development of nanotechnology,more and more artificial nanomaterials are widely used in daily life.Artificial nanomaterials will inevitably lead to the entry of nanomateri-als into environment during the process of production,transportation and use,causing potential risks to the ecological environment and human health.With the rapid growth of population in the world,the demand for the quantity and quality of food is constantly increasing,and the traditional pesticide has not met the demand of the agricultural production,vet the nanotechnology is likely to be a new platform for achieving the dynamic balance between the agricultural production and the environmental sustainability.In this study,two kinds of artificial nanomaterials,copper hydroxide(Cu(OH)2)and copper sulfide(CuS)were taken as model nanomaterials.On the basis of summarizing the research status and existing problems of Cu(OH)2 nanoparticles and CuS nanoparticles,we selected two systems which are of great significance for evaluating the environmental risks of Cu(OH)2 and CuS nanomaterials.In the first system,we studied the effect of Cu(OH)2 nanopesticide application on soil enzyme activity,microbial community and degradation of typical organic pollutants(thiacloprid).In the other system,we conducted research to shed light the mechanism for sulfidation of silver nanoparticles by copper sulfide in water that have not been clear.The purpose of this study was to evaluate the environmental risk of Cu(OH)2 nanoparticles and CuS nanoparticles by studying the effects of Cu(OH)2 nanoparticles on soil enzyme activity,microbial community,degradation of organic pollutants and the mechanism of silver nanoparticles sulfidation caused by CuS nanoparticles in water environment to evaluate the advantages and disadvantages of Cu(OH)2 nanoparticles compared with traditional CuSO4.And the environmental risk of CuS nanoparticles.The main results are as follows1.The effect of Cu(OH)2 nanopesticide on the soil environment compared with traditional CuSO4:urease activity,bacterial abundance(especially actinomycetes)and diversity and community decreased,yet catalase activity increased.These findings suggest that Cu(OH)2 nanoparticles can not only affect the activity of soil enzymes,but also reduce the abundance of bacteria and change the community structure of bacteria2.Compared with the traditional CuSO4,the conventional dosage of Cu(OH)2 nanopesticide can slow down the degradation of thiacloprid in soil.The specific influence way is that the adsorption of Cu(OH)2 nano pesticide reduces the bioavailability of thiacloprid.At the same time,Cu(OH)2 nanopesticide changes the soil microbial community,reduces the activity of nitrile hydrate enzyme and reduces the abundance of nth gene of thiacloprid3.The mechanism for sulfidation of silver nanoparticles by copper sulfide as S2-sources in water is that the cation exchange reactions(CERs).Dissolved oxygen is an important factor for silver nanoparticles to produce silver ions.The surface charge of CuS and different Ag/S molar ratios will affect the sulfidation rate.The natural organic matter,and inorganic salt also affect the silver nanoparticle sulfidation process.