PMID- 11348061
OWN - NLM
STAT- MEDLINE
DCOM- 20010802
LR  - 20190714
IS  - 0013-936X (Print)
IS  - 0013-936X (Linking)
VI  - 35
IP  - 7
DP  - 2001 Apr 1
TI  - Are PCBs in the Canadian Arctic atmosphere declining? Evidence from 5 years of 
      monitoring.
PG  - 1303-11
AB  - A long-term database of weekly air concentrations was examined to establish 
      temporal trends of PCBs in the Arctic atmosphere. Several methods were employed 
      to reduce the intra-annual variability allowing the elucidation of longterm 
      trends for a selection of congeners at Alert located in the Canadian Arctic. 
      These methods included temperature normalization (TN), multiple linear regression 
      (MLR), and digital filtration (DF). Estimation of the slope (m) resulting from 
      the linear regression between the natural logarithm of the partial pressure in 
      air versus reciprocal temperature (In P = m/T + b), required for TN and MLR, 
      proved difficult due to the poor correlation with temperature experienced forthe 
      majority of congeners. Values of m were considerably lower than those obtained 
      from temperate studies, implying that regional air-surface exchange plays a minor 
      role in supporting the observed air concentrations in the Arctic. The lighter 
      congeners generally showed very low slopes, and some even showed positive 
      correlation with 1/T. This might be a result of their relatively fast reaction 
      rates with OH radicals following the onset of 24-h sunlight in spring. Use of DF 
      (in combination with TN and MLR) revealed declining trends for several of the 
      lower chlorinated congeners in the high Arctic atmosphere, with estimated 
      first-order half-lives, t1/2, ranging from approximately 3 to 20 yr. Declining 
      trends of the lower congeners probably reflect falling levels in source regions, 
      as a result of long-range transport to this Arctic site. There were no apparent 
      trends for the higher chlorinated congeners (penta-substituted and above), 
      exceptfor PCB 180, in marked contrast to temperate studies, indicating a lag time 
      for decline between the Arctic and source regions.
FAU - Hung, H
AU  - Hung H
AD  - Meteorological Service of Canada, Downsview, Ontario. hayley.hung@ec.gc.ca
FAU - Halsall, C J
AU  - Halsall CJ
FAU - Blanchard, P
AU  - Blanchard P
FAU - Li, H H
AU  - Li HH
FAU - Fellin, P
AU  - Fellin P
FAU - Stern, G
AU  - Stern G
FAU - Rosenberg, B
AU  - Rosenberg B
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - United States
TA  - Environ Sci Technol
JT  - Environmental science & technology
JID - 0213155
RN  - 0 (Air Pollutants)
RN  - 0 (Chlorine Compounds)
RN  - 0 (Environmental Pollutants)
RN  - 0 (Free Radicals)
RN  - DFC2HB4I0K (Polychlorinated Biphenyls)
SB  - IM
MH  - Air Pollutants/*analysis
MH  - Arctic Regions
MH  - Chlorine Compounds
MH  - *Environmental Monitoring
MH  - Environmental Pollutants/*analysis
MH  - Free Radicals/analysis
MH  - Polychlorinated Biphenyls/*analysis
MH  - Temperature
EDAT- 2001/05/12 10:00
MHDA- 2001/08/03 10:01
CRDT- 2001/05/12 10:00
PHST- 2001/05/12 10:00 [pubmed]
PHST- 2001/08/03 10:01 [medline]
PHST- 2001/05/12 10:00 [entrez]
AID - 10.1021/es001704b [doi]
PST - ppublish
SO  - Environ Sci Technol. 2001 Apr 1;35(7):1303-11. doi: 10.1021/es001704b.