Resolving the Long-Term Trends of Polycyclic Aromatic Hydrocarbons in the Canadian Arctic Atmosphere
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- 作者：Sara Becker ; Crispin J. Halsall ; Wlodek Tych ; Hayley Hung ; Susie Attewell ; Pierrette Blanchard ; Henrik Li ; Phil Fellin ; Gary Stern ; Brian Billeck ; and Sheri Friesen
- 刊名：Environmental Science & Technology
- 出版年：2006
- 出版时间：May 15, 2006
- 年：2006
- 卷：40
- 期：10
- 页码：3217 - 3222
- 全文大小：373K
- 年卷期：v.40,no.10(May 15, 2006)
- ISSN：1520-5851
文摘
Polycyclic aromatic hydrocarbon (PAH) air concentrationsmeasured over the period 1992-2000 at the CanadianHigh Arctic station of Alert were subject to time-seriesanalysis using dynamic harmonic regression (DHR). For mostof the PAHs, the DHR model fit to the observed datawas good, with DHR capable of interpolating over missingdata points during periods when air concentrationswere below detection limits. As expected, DHR identifiedseasonal increases in PAH air concentrations. However, ithas also identified additional, subtler "seasonal" patternsas a series of harmonics with varying periodicity. Forexample, a regular summer high in air concentrations wasapparent for many PAHs, particularly the lower molecularweight (two- to three-ringed) compounds, which maybe attributed to summertime regional combustion eventssuch as forest fires and/or revolatilization from surfaces (e.g.,soil and oceans, as well as arctic surfaces). Comparisonof wintertime PAH concentrations (where 
PAH ranged from260 to 516 pg m-3) with an earlier arctic study did notreveal a reduction in PAH levels. However, removal of theseasonal components by DHR revealed a declining trendin PAH concentrations over the 1992-2000 period. For manylighter PAHs, this was typified by a linear decrease overthe whole time series, although, for the higher molecularweight PAHs, a marked reduction was apparent in the firstfew years of sampling followed by a leveling off inconcentrations by the mid/late-1990s. This behavior issimilar to reported trends of other air pollutants in the Arctic,may be attributed to the decline in Soviet industryduring the early 1990s, and has implications regarding themajor PAH sources affecting the Arctic.
PAH ranged from260 to 516 pg m-3) with an earlier arctic study did notreveal a reduction in PAH levels. However, removal of theseasonal components by DHR revealed a declining trendin PAH concentrations over the 1992-2000 period. For manylighter PAHs, this was typified by a linear decrease overthe whole time series, although, for the higher molecularweight PAHs, a marked reduction was apparent in the firstfew years of sampling followed by a leveling off inconcentrations by the mid/late-1990s. This behavior issimilar to reported trends of other air pollutants in the Arctic,may be attributed to the decline in Soviet industryduring the early 1990s, and has implications regarding themajor PAH sources affecting the Arctic.