F. Vandenberg et al., MEASURED AND COMPUTED CONCENTRATIONS OF 1,3-DICHLOROPROPENE AND METHYL ISOTHIOCYANATE IN AIR IN A REGION WITH INTENSIVE USE OF SOIL FUMIGANTS, Water, air and soil pollution, 78(3-4), 1994, pp. 247-264
A sampling programme was set up to measure 1,3-dichloropropene and met
hyl isothiocyanate in air in a region with intensive agricultural use
of these soil fumigants. In two consecutive autumns, 6-hour air sample
s were taken at two locations in that region with charcoal tubes using
automatic samplers. Most (81%) of the 6-hour concentrations of 1,3-di
chloropropene measured in both years were below 3.2 mu g m(-3) and a f
ew percent could not be measured with a detection limit of around 0.3
mu g m(-3). Only 4% of the 6-hour concentrations exceeded 10 mu g m(-3
), almost all of which were measured at a location where a field just
upwind of the measuring site had been treated. For methyl isothiocyana
te, 73% of the 6-hour concentrations of both years could not be measur
ed with a detection limit in the two years of 1 and 2 mu g m(-3), resp
ectively. A small fraction (3%) of the concentrations were in the rang
e of 3.2 to 10 mu g m(-3) and only 1% exceeded 10 mu g m(-3). The rate
s of emission of 1,3-dichloropropene and methyl isothiocyanate into ai
r were estimated for,weeks with many applications in the region studie
d. Using the PAL model, the concentration of fumigant in air at a rece
ptor site was computed for representative fumigations at different upw
ind positions. The computed concentrations in air ranged up to 9.9 mu
g m(-3) for 1,3-dichloropropene and up to 2.5 mu g m(-3) for methyl is
othiocyanate.