Further Studies on the Latitudinal and Temporal Trends of Persistent Organic Pollutants in Norwegian and U.K. Background Air

Data are presented for PBDEs, PCBs, and selected
organochlorine compounds, measured at background
locations by passive air samplers (semipermeable
membrane devices, SPMDs) along a latitudinal transect
from the south of the U.K. to the north of Norway during
2000−2002. This work is part of an ongoing air sampling
campaign in which PCB data were previously obtained
in 1994−1996 and 1998−2000. Comparisons of the masses
of chemicals sequestered by the SPMDs during these
different time intervals are used to investigate spatial
and temporal trends. The study yielded examples of
compounds that increase, decrease, or remain uniform
with latitude, suggestive of differences in the relative
importance of deposition versus atmospheric reaction
in controlling their long-range atmospheric transport
potential. The main constituents of the penta-BDE
product were detected at amounts equivalent to
2.0 (range 1.1−2.5) and 1.1 (0.8−1.6) pg m-3 for the
U.K. and Norway background sites, respectively.
Fractionation of PBDEs was observed, because the
amounts of lighter BDEs decreased with latitude, while
the heavier molecular weight congeners were quite
uniformly distributed. In contrast, the sequestered
amounts of the lighter PCBs were uniformly distributed
with latitude, with heavier PCBs decreasing. Sequestered
amounts of hexachlorobenzene increased with latitude.
Preliminary PCB atmospheric clearance rates were
derived using the 1994−1996, 1998−2000, and
2000−2002 data. They averaged ca. 3.5 years for all
congeners/locations. No systematic differences in
congeners or locations were noted, supporting the
hypothesis that the underlying trends in European
background air are still controlled by primary, rather
than secondary, sources.