Studies On Degradation Dynamics Of OCDPE In Soil And Its Accumulation In Soil-Tea System

The analytical methods and dynamics of Octachloropropyl ether residues in soil andtea were studied in this dissertation. The sensitivity, accuracy and precision of the methodswere investigated. The degradation and dissipation of OCDPE residues in soil were studiedboth in laboratory and field experiment.The Migration and accumulation of OCDPE insoil–tea plant system was studied in field experiment. The main results weresummarized as following:1. The analytical methods for OCDPE residues in soil and teaSoil sample was extracted with ethyl acetate by ultrasonic.Quantification analysis wasperformed by gas chromatography with an electron capture detector. Recoveries and RSDsof OCDPE in soil （the concentrations of OCDPE fortified in soil were0.01～1.0mg/kg）were82.3%～101.5%and7.4～9.9%,respectively. Tea sample was extracted withacetone/n-Hexane （2/1,v/v） by a mechanical.Quantification analysis was performed by gaschromatography with an electron capture detector. Recoveries and RSDs of OCDPE in tea（the concentrations of OCDPE fortified in tea were0.01～0.5mg/kg） were77.7%～92.3%and86%～10.4%, respectively. The accuracy, precision and sensitivity of this validatedmethod were suitable for analysis of OCDPE residue in soil and tea.2. Degradation of OCDPE residues in soilAt initial concentration of1.0mg/kg, the dynamic equation of OCDPE In red soil wasC_t=0.9362e^-0.0283t, and half-life (T_1/2) was24.40d. In yellow cinnamon soil, the dynamicequation was C_t=1.0307e^-0.018t, and half-life (T_1/2) was38.50d. In lime concretion black soil,the dynamic equation was C_t=1.0063e-0.0316, and half-life (T_1/2) was21.9d. At initialconcentration of10.0mg/kg, In red soil, the dynamic equation was C_t=9.8608e-^0.0296t, andhalf-life (T_1/2) was23.41d; In yellow cinnamon soil, the dynamic equation wasC_t=10.674e^-0.0177t, and half-life (T_1/2) was39.15d; In lime concretion black soil, thedynamic equation was C_t=10.451e^-0.0288t, and half-life (T_1/2) was24.06d.At initial concentration of1.0mg/kg, The field of OCDPE, the dynamic equation ofOCDPE in yellow cinnamon soil with the moisture of40%,60%and80%of field watercapacity were C_t=1.1629e-0.0193t, C_t=1.0307e^-0.018tand C_t=1.0447e-0.0141t, and the half-lives(T_1/2) were49.15d,38.50d and35.91d. 3．Dissipation of OCDPE residues in soil of tea gardenThe dissipation dynamic of OCDPE in soil of tea garden followed an apparentfirst-order kinetic model. In the soil, the dynamic equation of OCDPE was C_t=4.1524e^-0.1198t, and the dissipation half-life (T_1/2) of OCDPE in the soil was5.78d. Afterapplying OCDPE about20d, the dissipation rate of OCDPE in the soil was up to90%.4. Accumulation of OCDPE in soil-tea systemThe accumulation of OCDPE in fresh tea of the senile and young tea plants werestudied. The result showed that OCDPE was applied in soil of tea garden with sand at100g （a.i.）/hm². After55days, the concentration of OCDPE residue in fresh tea of the seniletea plant （15years） reached a maximum （0.1440mg/kg）. However, the concentration ofOCDPE residue in fresh tea of the young tea plant （7years） reached a maximum （0.3645mg/kg） after45d.During5d-55d after OCDPE being applied, the dynamic equation was C=0.0227e^-0.0566t，R²=0.9154. In fresh tea of the young tea plants, the dynamic equation wasC=0.0298^e-0.0306t，R²=0.7156.After the concentration of OCDPE residue in fresh tea of the senile and young teaplants reaching a maximum, OCDPE residue was dissipated. In fresh tea of the senial teaplants, the dissipation dynamic equation was C=1.5627e^-0.048t，R²=0.9634, and half-life(T_1/2) was14.4d; In fresh tea of the young tea plants, the dissipation dynamic equation wasC=3.8435e^-0.055t，R²=0.9698, and half-life (T_1/2) was12.6d.