Air–plant exchange of brominated flame retardants at a rural site: Influencing factor, interspecies difference, and forest scavenging

Abstract

Brominated flame retardants (BFRs) in eucalyptus leaves and pine needles from a rural site in southern China were measured to investigate the air-plant exchange. Mean concentrations of BFRs were higher in pine needles (79.8 ng/g dry wt) than in eucalyptus leaves (74.5 ng/g), whereas an inverse result was found for the leaf surface particles, with mean concentrations of 3490 ng/g and 5718 ng/g, respectively. For most of the BFRs, the correlations between their concentrations in plants and those in the vapor phase, atmospheric particles, leaf surface particles, and the environmental variables (temperature, wind speed, and relative humidity) at this site were in contrast to the results the authors observed at an electronic waste site previously, indicating that ambient air level plays a vital role in the relationships. The interspecies difference in the BFR profiles and the correlations above implied that pine needles likely have more advantages for uptake of BFRs from gaseous deposition than eucalyptus leaves, for which particle-bound deposition is more important. Like the electronic waste site, the leaf scavenging ratios of BFRs were also controlled by their octanol-air partition coefficient. It was estimated that approximately 154 kg of BFRs in the atmosphere are scavenged annually by forest in this region, which was 1.7 times larger than that via atmospheric deposition to nonforest ground.