Evaluation of Tree Bark as a Passive Atmospheric Sampler for Flame Retardants, PCBs, and Organochlorine Pesticides

To investigate the relationship between the levels of persistent organic pollutants in tree bark (a passive sampler) and those in air and precipitation, tree bark and air and precipitation samples were collected during the same time period at the five U.S. Integrated Atmospheric Deposition Network (IADN) sites located in Great Lakes basin. The concentrations of polybrominated diphenyl ethers, Dechlorane Plus, decabromodiphenyl ethane, polychlorinated biphenyls, DDTs, and chlordanes were measured in these samples. Overall, the pollutant concentrations in tree bark are significantly related to the concentrations of these compounds in the air and precipitation collected where the tree was growing. Generally, the highest tree bark and air pollutant concentrations were observed at urban sites, and the lowest concentrations were observed at remote sites. The overall correlation between bark and atmospheric and precipitation concentrations for all the compounds measured in this study was highly significant (P < 0.0001) over 3-4 orders of magnitude. In addition, bark-air partition coefficients, measured for all the chemical categories in this study, were about 10(6), which was in good agreement with previously estimated bark-air partition coefficients for corresponding pollutant groups.