Soot sorption of non-ortho and ortho substituted PCBs.
Field-observations of distribution coefficients well above expectations from bulk organic-matter partitioning for several chlorinated aromatic compound classes have lead to the hypothesis that enhanced affinity to soot may not be limited to polycyclic aromatic hydrocarbons but may extend as a significant process for a wider range of hydrophobic organic compounds. This suggestion was here tested in soot-column sorption experiments with a series of ortho- and non-ortho substituted polychlorinated biphenyls (PCBs), using diesel particulate matter (NIST standard reference material SRM-1650) as model soot sorbent. For congeners of similar hydrophobicity, considerably higher affinities toward the soot sorbent were observed for the non-ortho substituted PCBs. Mono- to tetra-ortho substituted PCBs exhibited log-based soot-water distribution coefficients (K(sc)) from 5.25 to 5.51 l/kg(sc) at solute concentrations corresponding to 1-13 microg/l. In contrast, biphenyl, mono- and dichloro- non-ortho substituted PCBs yielded logK(sc) values between 5.09 and 6.35 l/kg(sc). These results are 20-50, and 75-110 times higher, respectively, than the corresponding K(ow)-predicted K(oc) numbers. This strong interaction with soot, particularly of non-ortho substituted PCBs, may fundamentally affect their environmental distribution and bioavailable exposure.
Bucheli
Thomas D
TD
Institute of Applied Environmental Research, Stockholm University, S-10691 Stockholm, Sweden. thomas.bucheli@fal.admin.ch
Gustafsson
Orjan
O
D000327:Adsorption; D002244:Carbon / Q000032:analysis*; D004785:Environmental Pollutants / Q000032:analysis; D011078:Polychlorinated Biphenyls / Q000737:chemistry*; D001335:Vehicle Emissions / Q000032:analysis
D004785:Environmental Pollutants; D001335:Vehicle Emissions; D002244:Carbon; D011078:Polychlorinated Biphenyls