Aerial short-range dispersion of volatilized pesticides from an area source.
Owing to legal provisions, pesticides have to be applied in such a way that there is no unacceptable influence on human health and the environment at nearby non-target areas. In order to quantify their concentration over and downwind of agricultural target plots of 0.5-1 ha, covered by winter wheat and winter barely, the pesticides lindane, parathion and pirimicarb were applied. Over these plots the post-application volatilization rates of the pesticides were estimated indirectly from vertical concentration, wind and temperature profile measurements using the aerodynamic gradient technique. Philip's advection model was applied to take non-favourable fetch conditions into account. In addition, at a height of 1.6 m downwind of the area source, measurements of the horizontal concentration profile were made up to a distance of about 250 m at roughly 50-m intervals. The monitoring started immediately after spraying in the morning and continued for about 8-10 h, thus providing a worst-case situation because volatilization, and therefore pesticide concentration in the atmospheric surface layer, is then strongest. The concentration of the airborne pesticides over the downwind non-target area was also calculated by Philip's advection model. By using the Nash-Sutcliffe relative-difference measure between observed and calculated concentrations, a goodness-of-fit of 0.97 was obtained over the downwind non-target area, indicating that the Philip model is well suited for dispersion estimates in the near-field range.
Wittich
K-P
KP
Deutscher Wetterdienst, Agrarmeteorologische Forschung, Bundesallee 50, 38116 Braunschweig, Germany.
Siebers
J
J
D000383:Agriculture; D000397:Air Pollution / Q000517:prevention & control; D004782:Environmental Health; D006801:Humans; D008685:Meteorological Concepts; D008962:Models, Theoretical; D010575:Pesticides / Q000009:adverse effects / Q000032:analysis*; D014835:Volatilization
D010575:Pesticides