Transformation rate of 1,3-dichloropropene and 3-chloroallyl alcohol in topsoil and subsoil material of flower-bulb fields

The extent of the risk of (Z)- and (E)-1,3-dichloropropene and their transformation products (Z)- and (E)-3-chloroallyl alcohol causing a hazard to the quality of groundwater pumped up for public water supply from below flower-bulb fields has been evaluated. The 1,3-dichloropropenes were incubated at 10°C in water-saturated subsoil material from three such fields. A first stage with gradual transformation was followed by a second stage with comparatively rapid transformation and after three months negligible amounts remained. The 3-chloroallyl alcohols were incubated at 15°C in soils from the root zone of the same fields. Complete transformation had occurred in about a week or even less. The 3-chloroallyl alcohols were also incubated in the water-saturated subsoil material at 10°C. Again, a first stage with gradual transformation was followed by a second stage with fast transformation. In most instances, the concentrations had fallen to a very low level within three months. It was concluded that it is unlikely that residues in the upper groundwater would permeate into the deeper groundwater pumped up for public water supply.