2002 Volume 51 Issue 2 Pages 127-128
A new dynamic model for predicting of pesticide concentrations in the atmosphere has been developed. The trapping method has also been studied for determining of trace pesticides in the atmosphere. Concerning trapping, the most suitable adsorbents for soil fumigants and pesticides were Porapak T and silica gel, respectively, because of their high enrichment efficiencies and high break-through volume, as well as having good stability of the adsorbed chemical species on the adsorbent. The concentrations of the pesticides, fumigants and their transformed products were measured by GC or HPLC after their dispersion over a paddy field. No transformed products, such as fenitrooxon or N-nitrosofenobucarb, were detected. After air samples at 1.5∼100 m and 150∼800 m in height were collected in flight with a helicopter, the concentrations of pesticides were determined with GC/MS (SIM). The volatilization rates of the pesticides, and the partition ratios of the pesticides between air/water, air/soil, air/rice leaf and air/glass surface, respectively, were measured. Afere the concentrations of the soil fumigants were measured on a soil surface, their emission ratios were calculated as the emission weight divided by the applied weight. The correlation between the volatilization rates and the physicochemical properties were analyzed. Finally, a general model to predict the concentration of pesticides in the atmosphere outside of a sprayed area was developed using the results of the measured concentrations in reference to the atmospheric diffusion model used for an air pollution prediction model.
