Semivolatile Organic Contaminants in the Hawaiian Atmosphere.

An air sampling campaign on the Island of Hawaii aimed to assess background concentrations of semivolatile organic compounds (SVOCs) over the Central Northern Pacific and to explore their distribution along an altitudinal transect. XAD-resin-based passive air samplers were deployed from May to September 2011 at six sites along a transect from the northeastern coast to the Mauna Loa Observatory and at three other island sites. By crossing the trade wind inversion, the transect comprised the marine boundary layer and free troposphere. At the two ends of the transect, flow-through samplers simultaneously sampled air at monthly resolution. Elevated levels of dieldrin, chlordane- and DDT-related pesticides, polycyclic aromatic hydrocarbons (PAHs), and polybrominated diphenyl ethers (PBDEs) at two urban sites indicated contributions from local sources. The composition of chlordane and DDT-related residues indicated recent emissions. PAHs concentrations that decline more rapidly with increasing elevation than those for PBDEs are consistent with faster atmospheric degradation of PAHs. SVOC levels on Mauna Loa were generally at the lower end of concentration ranges reported for remote sites, including the Arctic. However, in contrast to the Arctic, long-range atmospheric transport is deemed less important than human-induced material flow as the source of SVOCs to the island's atmosphere.