A STUDY OF THE SPATIAL-DISTRIBUTION OF PCBS IN THE UK ATMOSPHERE USING PINE NEEDLES

Past and current polychlorinated biphenyl (PCB) inputs to the environm ent, mainly in industrialized countries, continue to determine a globa l re-distribution of these contaminants. In order to better understand PCB transport and distribution phenomena, a number of large-scale dis tribution studies have been recently published in the literature. In t his paper a nationwide survey of 28 pine needle samples taken across t he UK is presented. Mean PCB concentrations of a number of latitudinal bands (transects) revealed the presence of a decreasing concentration gradient from southern England to northern Scotland of a factor of si milar to 7. The pine needle data also provide evidence to suggest: 1) that there has been a decrease in the PCB concentration of the atmosph ere in the southern UK; and 2) there is a relationship between regiona l mean needle PCB concentrations and population densities. Calculated air concentrations from the pine needle results were compared with mea sured literature data of a similar area to test the possibility of usi ng bioconcentration factors (BCF) based on n-octanol:air partition coe fficients (Koa) to predict air-leaf equilibrium of semivolatile organi c compounds. A more detailed analysis, in accordance with some literat ure data, has revealed that uncertainties arise when leaf-air uptake o f molecules with high Koa values (Log Koa > 8-9) is modelled. Copyrigh t (C) 1996 Elsevier Science Ltd