The Toxic Effect Study Of Four Metal Oxide Nanoparticles On Agricultural Soil Microorganism

Nanoparticles, in particular, those used for engineering purposes, are microscopic particles with at least one dimension that is 1-100 nm in length. Nanotechnology will influence the world economy in the 21st century by impacting industry and living standards. To understand nanoparticles'migration, transformation, enrichment in the environment and absorption mechanism, it is very important to evaluate environmental behavior and ecological toxicity of nanoparticles. These are the basic premises of the development and application of nanoproducts.The combination of soil heat metabolism, functional bacteria and enzyme activity to evaluate the toxicity of nanoparticles in agricultural soil is shown to be successful. Four kinds of metal oxide nanoparticles ?ZnO and SiO₂, TiO₂ and CeO₂? are used as test materials. Through total heat production of soil microbial, abundance of functional microbial and the change of plant physiology, environmental behaviors of nanoparticles exhibit the following three aspects:1, There is significant difference in toxicity between 1 mg kg^-1 ZnO and SiO₂, TiO₂ and CeO₂ nanoparticles on soil microorganisms. While ZnO and CeO₂ nanoparticles showed an obvious inhibiting effect on soil microbial activity, TiO₂ and SiO₂ did not. According to thermal parameters of nanoparticles, Pmax and k value, their toxicity can be listed in the following order:ZnO> CeO₂> TiO₂> SiO₂.2, ZnO and CeO₂ nanoparticles exhibit dose effect in agricultural soil ecosystem. According to the calculation of thermal parameter, EC₅₀ of ZnO and CeO₂ nanoparticles on agricultural soil microbial activity are 103.19 and 518.49 mg kg^-1. This can be used as a reference basis for future applications on pesticides or insecticides.3, SiO₂ nanoparticles ?9 nm,12 nm,40 nm? with different concentrations (10, 25,50 mg kg^-1) have no toxic effect on soil microorganism. The results confirm that SiO₂ nanoparticles can improve the metabolic ability of soil microorganisms.4, Compared to the control group, phytotoxicity results show that ZnO and CeO₂ nanoparticles have an inhibitory effect on seed germination and root enlongation, and photosysnthesis. TiO₂ and SiO₂ do not have inhibiting effect; phytotoxicity of nanoparticles depends on size and the amount of metal ions released in soil.