Volatilization of dieldrin and heptachlor from a maize field

Abstract

Dieldrin and heptachlor were applied at 5.6 kg/ha and mixed 7.5 cm deep in the soil immediately before maize planting on a 0.68-ha watershed at Coshocton, Ohio, on April 30,1969. Vapor density profiles up to 4 m above the ground were measured on 7 days between May 2 and October 16. Vertical flux densities were calculated from eddy diffusion coefficients determined from simultaneous micrometeorological observations. Maximum flux intensities of 4.0 g/ha per day of dieldrin and 5.0 g/ha per day of heptachlor were observed on June 26th. Marked diurnal variations with noonday maxima were observed. Flux intensities declined to low values in October. Calculated seasonal losses were 199 g/ha of dieldrin and 383 g/ha of heptachlor.The importance of volatilization as a significant pathway for organochlorine insecticide loss from soils was noted by Lichtenstein and Schultz (1961). Later, Lichtenstein et al. (1964) showed that losses of aldrin and dieldrin were greatly reduced when the insecticides were incorporated to the 4 in. depth in the soil than when they remained on the surface without cultivation; they attributed this difference to the higher evaporation of the exposed material. Toxic concentrations of insecticide vapors in the air over soils treated with aldrin, heptachlor, and other insecticides were demonstrated by Harris and Lichtenstein (1961) who also showed that the vapor concentration, measured in terms of toxicity, was affected by temperature, humidity, and airflow. Spencer et al. (1973) reviewed measurements

Volatilization of dieldrin and heptachlor residues from field vegetation

“…Similar diurnal variations have also been reported in the volatilization of heptachlor and dieldrin residues incorporated into surface soil (Taylor et al, 1976). In the earlier work the diurnal variation was attributed to changes in water movement to the soil surface controlled by surface water evaporation-the "wick effect".…”

“…Considerable attention has been devoted to studies of pesticide movement through soils and the extent to which volatilization rates are related to diffusion. Although some measurements of rates of insecticide volatilization from soils under field conditions have been published (Taylor et al, 1976;Willis et al, 1971Willis et al, , 1972, little or no data are available concerning rates of volatilization from exposed plant or vegetation surfaces in the field.…”

“…The work described here was designed to measure the volatilization of dieldrin and heptachlor, two chemically persistent insecticides, over a period of 3 weeks of warm summer weather after their application to field vegetation. The two insecticides were chosen to give data directly comparable with that from other studies in which they were incorporated to the 7.5 cm depth of surface soil (Taylor et al, 1976). Suitable techniques for measurement of their concentrations in the air over the treated field, together with the necessary analytical methods, were also available .…”

Volatilization of Microencapsulated and Conventionally Applied Chlorpropham in the Field1

“…I and 2). Similar dependence on solar energy was found in the volatilization of dieldrin and heptachlor from soil and vegetation (14,15) and trifluralin from soil surfaces (D. E. Glotfelty, personal communication).…”

Volatilization of surface-applied pesticides from fallow soil

“…Using this technique, Willis et al (1972) estimated dieldrin losses from flooded, moist, or nonflooded fallow soil. Taylor et al (1976) estimated seasonal losses of dieldrin and heptachlor incorporated into the soil of a growing corn crop. In a follow-up study, Taylor et al (1977) compared losses of these same two pesticides from a 10-cm stand of orchard grass.…”