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Study on the Residue Dynamics of Atrazine and Acetochlor in Maize and Soil

Field trials and Gas Chromatography-Mass Spectrum(GC-MS) were conducted to study the residual dynamics and final residues of atrazine and acetochlor which were widely used as herbicides in maize and soil.The results showed that,the limits of determination for the atrazine and acetochlor were 0.08 ng g-1 and 0.40 ng g-1,respectively.When the added concentration of atrazine and acetochlor ranged from 10 ng g-1 to 250 ng g-1,the recoveries changed individually from 85% to 97% and from 102% to 109%,and their respective relative standard deviations varied from 10.0% to 14.4% and from 9.7% to 14.0%,respectively.The kinetic equations of atrazine and acetochlor degradation in soil were C=1942.7e-0.0492T and C=916.53e-0.0343T and the half lives were 14.1 d and 20.2 d,respectively.According to the research,if atrazine and acetochlor were sprayed between maize sowing and seedling emergence,and when atrazine 38% aqueous suspension concentrate was applied one time to control the weeds in maize field with the dosages of 5.25-10.50 g hm-2,the final residues of atrazine in maize seed were less than 0.08 ng g-1 and the final residues in soil were less than 3.3 ng g-1.And when 900 g L-1 acetochlor emulsion pesticide was applied one time to control the weeds in maize field with the dosages of 2.25-4.50 g hm-2,the final residues of atrazine in maize seed were less than 0.40 ng g-1 and the final residues in soil were less than 12.4 ng g-1.All the residual values were up to the relevant limit standards.