Study On The Degradation Of Xiangcaoliusuobingmi,Novel Antiviral Pesticide In Aerobic Soils

Xiangcaoliusuobingmi is a novel antiviral pesticide successfully developed by Guizhou University and has independent intellectual property rights in China.In order to ensure the safety of environment and agricultural products,and to realize the industrialization and commercial application of vanillin thiotropic ether,it is urgent to study environmental behavior and fate of Xiangcaoliusuobingmi in aerobic soils.In this thesis,¹⁴C-labeled Xiangcaoliusuobingmi compounds A and B in different positions were used as tracers that can reflect molecular characteristics of this pesticide.Four typical soils with different properties were selected as test soils,and liquid scintillation technology and modern instrument analysis technology were comprehensively used in this research.The environmental behavior and fate of Xiangcaoliusuobingmi in soil under aerobic conditions were systematically studied,and the dynamic transformation rules of different occurrence forms of extractable residues,bound residues and mineralization were clarified from the perspective of conservation of mass.The degradation dynamics and laws of pesticides in different soils were revealed,and the use of high-throughput sequencing technology to evaluate the effect of Xiangcaoliusuobingmi on soil microbial diversity,aimed at assessing the environmental safety of Xiangcaoliusuobingmi scientific,reasonable and safe use provides theoretical basis and data support.The main findings are as follows:（1）Mass balance:The total radioactive recovery rates of ER,BR and mineralization of Xiangcaoliusuobingmi in five soils（ponderosa pine soil,sterilized ponderosa pine soil,red sandy soil,moisture soil,chernozem）were 85.7-112.1%,92.9-111.9%,92.2-103.4%,83.7-103.6%,95.2-102.7%,respectively.It shows that this study conforms to the good ¹⁴C quality conservation law.（2）ER,BR and mineralization laws:1)The variation range of extractable residues in each soil is:9.9%（ponderosa pine soil）,24.5%（sterilized ponderosa pine soil）,28.3%（red sandy soil）,13.4%（moisture soil）,31.8%（chernozem）.There was no significant difference in the ER contents of A and B in ponderosa pine soil and moisture soil,while there was significant differences in the ER of red sandy soil and chernozem after 12 d and 10 d of cultivation,respectively.The ER of sterilized soil was always significantly higher than that of unsterilized soil.2)The variation range of the BR in each soil were:52.9%（ponderosa pine soil）,38.4%（sterilized ponderosa pine soil）,32.3%（red sandy soil）,33.3%（moisture soil）,63.8%（chernozem）.The order of the BR was as follows:chernozem>ponderosa pine soil>sterilized ponderosa pine soil>moisture soil>red sandy soil.3)The mineralization amount of Xiangcaoliusuobingmi was different in different soils.There was no significant difference in mineralization between ponderosa pine soil and sterilized soil at different marker sites,and there were significant differences in the remaining three soils.The amount of mineralization was 45.9%-46.0%（ponderosa pine soil）,20.4%-21.5%（sterilized ponderosa pine soil）,25.0%-36.1%（red sandy soil）,38.2%-41.7%（moisture soil）,1.55%-1.77%（chernozem）.（3）Maternal degradation and metabolite dynamics:The degradation of Xiangcaoliusuobingmi in the test soil under aerobic conditions was mainly biodegradation.The half-lives of Xiangcaoliusuobingmi in the ponderosa pine soil,red sandy soil,moisture soil and chernozem in soils were 2.68 d,1.01 d,4.44 d,12.10d,respectively.The degradation rate of the four non-sterilized soils from fast to slow was red sandy soil>ponderosa pine soil>moisture soil>chernozem.According to"Chemical Pesticide Environmental Safety Evaluation Test Standard Test",this pesticide belonged to easily degradable pesticide.The LC-LSC results showed that the metabolites formed by Xiangcaoliusuobingmi in the ponderosa pine soil and moisture soil had the same types of metabolites,with 5 metabolites;5 metabolites in red sandy soil;4 metabolites in chernozem.The metabolite formed by A is more abundant than B.M3,M4 and M5 were the main metabolites of Xiangcaoliusuobingmi.According to the radioactive peak characteristics and mass spectrometry information,it is speculated that M3 is 4-（（4-chlorobenzyl）oxy）-3-methoxybenzoic acid,M4 is 4-（（4-chlorobenzyl）oxy）-3-methoxybenzaldehyde,and M5 is 2-（4-（（4-chlorobenzyl）oxy）-3-methoxyphenyl）-1,3-oxathiolane.（4）Effects of soil microbial diversity:Results showed that the main fungi common in the tested soils include Ascomycota and Basidiomycota,and there are obvious differences in the diversity of the fungal communities in the four soils.In the same soil,the application of Xiangcaoliusuobingmi has no significant effect on fungal diversity;bacteria shared by the test soil mainly include Acidobacteria,Actinobacteria,Bacteroidetes,Planctomycetes,Proteobacteria,Rokubacteria.There is a temporary difference in the bacterial richness in each soil after application,and there is also a temporary difference in the composition of the soil bacterial community after the application in moisture soil and chernozem.