| Nicosulfuron was found in the United States in 1989,which is a kind of sulfonylurea herbicide.DuPont compangy introduced it during the pyridine-ethyl (flazasulfuron, grass-specific herbicides) found in the research process.Nicosulfuron is mainly used for preventing cornfield more lower toxicity and dosage characteristic,which is used widely.However,the issues of the degradation and the residue in soil has become increasingly concerned by scientific workers.In this paper,nicosulfuron's residue analysis method in plant,green corn,mature seed and soil was improved.Using HPLC for the research of its degradation dynamic and the final residual.This method provides the basis for formulating residual standard.The nicosulfuron degraddtion strains N80 and bioremediation of contaminat-ed soil were studied further.Aimed at nicosulfuron appeared in the process of environ-mental problem solving for reference.Soil samples were extracted by acetonitrile and water mixture.Decompression suction filter were deal with in brinell funell funnel with filtration did agent 545.The filtrate was collected with 7g of sodium chloride in 100ml graduated cylinder and oscillated for 1 min.Still,after a plug from the cylinder to draw 40ml evaporated nearly dry.Volume by methanol and welect Zorbax Q18 column with methanol and acetic acid acidification of the water mixture as mobile phase for high performance liquid chrom-Atography(HPLC)analysis.Maize,green maize and mature seeds have been extracted with chloroform and purificated by C18 SPE cartidge.After volume with methanol.the sample is under test by HPLC. Other pretreatment and analytical steps is the same with the soil samples.Take thre add levels are 0.05,0.1 and 1.0mg/kg,method recovery is during 84.2%and 109.1%.Coefficient of variation is 1.9%-12.3%,the sample minimum detected concentration is 0.006mg/kg.Two years' field experiments were done in Chang Chun city of Ji Lin province and Hai Lun city of Hei Longjiang province in 2009 and 2010.75% nicosulfuron WG treated soil and corn samples with 120g/667m2 and 80g/667m2 and did dynanic analysis of residual.Degradation process conform to level kinetics reaction model C= COe-kt. In the soil two years between dynamic equations were C=6.9436e-0.0835t, r= 0.8924, half-life is 5.1d (2009 Ji Lin); C=5.358e-0.0955t, r=0.9456, half-life is 3.8d (2009 Hei Longjiang); C=1.6317e-0. 0617t,r= 0.7772, half-life is 4.6d (2010 Ji Lin); C= 2.7014e-0.0508t,r=0.8396, half-life is 3.8d (2010 Hei Longjiang).The dynamic equation in maize plants were C=45.116e-0.2603t, r=0.8601, half-life is 0.9d (2009 Ji Lin);C= 51.25e-0.33921, r=0.851, half-life is 0.2d (2009 Hei Longjiang); C= 9.9624e-0.0848t, r=0.649, half-life is 2.0d (2010 Ji Lin); C= 15.377e-0.1835t, r=0.8933, half-life is 1.9d(2010 Hei Longjiang).The results showed that:the digestion rate of nicosulfuron in soil and corn plant is faster,the half-life is shorter,this pesticide is easily degrated(t1/2 is less than 30 days).The final residues determination results show that:the soil in 2009 and 2010 has been detected,the others were lower than 0.05mg/kg.The result of N80 solid bacterium agent show that:the best formula of carrier is 7% pupa powder+ 3%Silkworm powder+15%sawdust+75%Wheat gluten, diatomite(9:1).The best process conditions is inoculation quantity(10%),fermentation temperature (25℃),fermentation time(24h) and drying time(48h).Preparation of the above condit-ions,the better N80 stability of solid agents after 60d storage at 25℃for nicosulfuron can still maintain a high degradation.The bioremediation experimental results show that:with the exogenous strains N80 can promote the degradation of nicosulfuron in the contaminated soil.At the 30th days,the highest degradation rate is 79.7%.The most suitable conditions of degradation of nicosulfuron by N80 in soil is 25℃,pH=7.0, inoculation quantity(108cfu/g) and initial concentration(10mg/kg).Pot experiment showed that:the hand-actuated inoculation of N80 strain could effectively increase degradation rate of nicosulfuron in contaminated soil.This experiment achieve the desired effect of bioremediation. |
