The Behavior Of Pesticide Residues In Chrysanthemun And Cultivated Soil

A simple, rapid residue analytical method of chlorpyrifos in Chrysanthemum flower and soil was developed. The fortified recoveries of chlorpyrifos in analytical samples were in range of80.37%～97.55%, with relative standard deviations of1.06～9.93%. The detectable limit of FPD for chlorpyrifos is0.001ng, and the mminimum detectable concentration is0.0001mg·kg-1in soil,0.0004mg·kg-1in fresh bud and flower,0.0002mg·kg-1in dry bud and flower. The residue analytical method of carbendazim in Chrysanthemum flower and soil was studied. The fortified recoveries of carbendazim in analytical samples were in range of84.03%-95.19%, with relative standard deviations of1.32～9.86%. The detectable limit of HPLC for chlorpyrifos is0.3ng ng, and the minimum detectable concentration is0.01mg·kg-1in soil,0.05mg·kg-1in bud and flower.According to the result of residue test under the control condition of10,20,30℃, degrading speed of chlorpyrifos and carbendazim in soil, dry bud and dry flower were related to the temperature. The higher temperature was, the higher degrading speed was. The half lives of chlorpyrifos in soil were17.72d(10℃),14.14d(20℃),10.35d(30℃), in dry bud were27.39d(10℃),19.74d(20℃),12.64d(30℃), in dry flower were38.08d(10℃),22.87d(20℃),15.29d(30℃). The half lives of carbendazim in soil were19.69d(10℃),10.64d(20℃),7.65d(30℃); in dry bud were45.30d(10℃),33.16d(20℃),26.55d(30℃); in dry flower were49.86d(10℃),40.06d(20℃),33.00d(30℃).The result of degradation of chlorpyrifos and carbendazim in soil of different moisture showed that:the half lives of chlorpyrifos in the soil of dry, field capacity and submerged condition were36.58d,33.00d and38.01d; the half lives of carbendazim in the soil of dry, field capacity and submerged condition were47.46d,35.73d and2.30d.Results of field test showed that the half lives of chlorpyrifos were9.87～12.49d (2011～2012) in soil;4.74～5.27d (2011～2012) in bud;3.99～4.56d (2011～2012) in flower. It is30days that the chlorpyrifos residue in bud and flower was degraded below0.5mg·kg-1. So it was predictable that0.48kg·hm-2chlorpyrifos was sprayed once a year and30days were proposed as the minimum preharvest interval of chlorpyrifos in the Chrysanthemum flower to make the dry Chrysanthemum flower safe. The half lives of carbendazim were7.98-8.34d (2011～2012) in soil;3.90-4.05d (2011～2012) in bud;3.37～3.45d (2011～2012) in flower. so it was predictable that0.675kg·hm-2carbendazim was sprayed once a year and21days were proposed as the minimum preharvest interval of carbendazim in the Chrysanthemum flower to make the residue of carbendazim in the dry Chrysanthemum flower below the MRL.