Study On The Residual Distribution Of Carbendazim In Rape Planting System And The Effect Of Biochar On The Environmental Behavior Of Carbendazim

Carbendazim is a broad-spectrum benzimidazole fungicide for foliar spray,seed treatment and soil treatment.It is caused by fungi(such as deuteromycetes,polycyspores)on many crops.Good control effect,widely used in China,large amount of use.However,carbendazim is chemically stable,has a long residual period,is toxic to mammals,can penetrate into plants through crop leaves and seeds,and can cause poisoning through the esophagus.Biochar has rich pore structure and surface functional groups,and has a large specific surface area and strong stability.The biochar modified soil can enhance the adsorption capacity of pesticides,reduce the leaching of pesticides and the toxicity to soil organisms..Therefore,research on the residual distribution and control factors of carbendazim in the rapeseed system and the effects of biochar on the environmental behavior of carbendazim are important for reducing the use of carbendazim and its toxic effects on the soil environment..In this paper,the relationship between the deposition and distribution of carbendazim in the rapeseed system,the digestion dynamics,and the application amount and deposition amount were studied systematically.The adsorption characteristics of three biochars to carbendazim were studied by isothermal adsorption test and adsorption kinetics test.Aiming at the residual pollution of carbendazim in farmland,the elimination of carbendazim in soil by three biochars was investigated.The main research results are as follows:1.A liquid chromatography residue analysis method for carbendazim in leaves,stems,seed pods,flowers and soil of rapeseed was established.The linear relationship of carbendazim in the concentration range of 0.1～50 mg/L is good.The linear regression equation is:Y= 90.762x+20.047,R2=0.9999,the minimum detection amount(LOD)is 0.02 ng,the lowest detection concentration(LOQ)It is 0.1 mg/kg.The recoveries of rapeseed leaves,flowers,stems,seed pods and soil were 82.9%～97.6%,83.8%～108%,80.3%～90.9%,86.5%～90.7%and 77.0%～95.8%respectively,in line with residue analysis requirements.2.90% carbendazim WP was applied to rapeseed in Qinghai Muxiang,Nanjing,Jiangsu and Changsha,Hunan.The results showed that the degradation of carbendazim on rapeseed,leaf,pod and stem was consistent with first-order dynamics.Learn the equation.The average half-lives of carbendazim on rape,leaves,pods and stems were 2.5,9.5,7.1 and 5 days,respectively.The degradation of carbendazim in soil did not conform to the first-order kinetic equation.3.The risk assessment of carbendazim was carried out by the Food Safety Application Threshold Calculator and the Risk-Free Pesticide Amount Calculator for Birds,Peas,and Bees.The results showed that the field use of carbendazim was much lower than the food safety threshold,and the bee and bee were There is no risk of exposure and there is no acute toxicity risk to birds,but there is a risk of chronic toxicity.Finally,the safe application limit of carbendazim on rapeseed was 1120-2500 a.i.g/ha.4.The effects of biochar addition on carbendazim adsorption were studied by adding three kinds of biochar in the black soil of Northeast China.The results showed that the adsorption capacities of the three biochars were:shell charcoal>rice straw charcoal>coconut shell charcoal,adsorption The rate is:shell charcoal>rice straw charcoal>coconut shell charcoal.After the addition of shell charcoal,the theoretical maximum adsorption capacity of black soil in Northeast China increased from 46.30μg/g to 215.23 μg/g.After adding rice straw charcoal,the theoretical.maximum adsorption capacity of black soil in Northeast China increased from 46.30μg/g to 117.26.μg/g,the addition of coconut shell charcoal to the carbendazim theoretical maximum adsorption amount does not change much.5.The aging test of shell charcoal and rice straw charcoal with good adsorption performance was carried out to study the effects of physical treatment,natural aging and oxidative aging on the adsorption capacity of carbendazim.The results showed that the theoretical maximum adsorption capacity of carbendazim increased after physical aging,and the theoretical maximum adsorption amount of carbendazim decreased after natural aging and oxidative aging.6.Adding 0.3% nut shell carbon,0.3% rice straw carbon,0.3%coconut shell carbon,0.6%shell carbon,0.6%rice husk,0.6%coconut shell charcoal under indoor conditions,carbendazim The half-lives were 16.2 days,16.1 days,63 days,53 days,49.5 days,and 43.3 days,respectively,which were less than 99 days without biochar addition.42 days after the addition of biochar under outdoor conditions,the content of carbendazim in the soil was>1%in the northeast soil>1%in the carbon soil>1%coconut shell carbon>1%shell carbon.It indicates that biochar can accelerate the reduction of the effective carbendazim content in the soil.7.Earthworm is very sensitive to carbendazim in the soil and has an avoidance effect.The evasive effect of hydrazine on carbendazim is studied by adding nutshell biochar to the soil containing carbendazim.The test results showed that the addition of 1%shell charcoal in the soil containing 5mg/kg reduced the avoidance rate of cockroaches from 100%to 60%,indicating that biochar reduced the concentration of carbendazim in contact with carbendazim.It reduces the avoidance effect of hydrazine on carbendazim.