Field derived accumulation and release kinetics of DDTs in plants

Vegetation plays an important role in influencing the air/surface exchange of semivolatile organic compounds (SOCs). In order to predict the capability of different plant species to capture chemicals from the air, plant-air partition coefficients and kinetic accumulation parameters must be defined. In this study, potted plants of three different species were transferred to the vicinity of a source point for DDT, namely a contaminated area around a former production plant in Italy. Leaves were constantly sampled in order to follow the uptake from air over time. Later, the potted plants were transported to a location characterized by background diffuse air concentrations for the release phase. Coupling the experimental results with a two-compartment accumulation model it was possible to derive the kinetics parameters and the plant-air partition coefficient K(PA) for p,p'-DDT. The logK(PA) (on a mass/volume basis) ranged between 1.7 and 2.2 for the different species. The uncertainties related to the different phenomena involved in a field uptake/release experiment are discussed.