Influence of background particulate matter (PM) on urban air quality in the Pacific Northwest.
Influence of background particulate matter (PM) on urban air quality in the Pacific Northwest.
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DOI：
10.1016/j.jenvman.2013.07.023
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发表时间：
2013-11
影响因子：
8.7
通讯作者：
H. Timonen;N. Wigder;D. Jaffe
中科院分区：
文献类型：
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作者：
H. Timonen;N. Wigder;D. Jaffe
由于亚洲远距离输送（LRT）引起的颗粒物浓度升高在美国太平洋西北部上空的自由对流层（FT）中经常观察到，这种气溶胶从FT到边界层（BL）的输送及其对当地空气质量的影响仍然很少受到限制。我们利用巴舍山观测站（MBO, a.s.l 2.8 km）和太平洋西北部地面站收集的数据，研究了从FT到BL的细颗粒物（PM）的输送。在亚洲LRT期间，MBO以及华盛顿和俄勒冈州的低海拔地区的PM浓度明显高于相应的月平均值。此外，观察到MBO与低海拔部位之间存在明显的相关性，表明在FT和BL中都可以看到LRT发作。此外，鼓式冲击器测量显示MBO处PM的化学成分与BL部位相似。利用简单回归模型估计，在亚洲输送最有效的春季，亚洲源对太平洋西北清洁背景区pm2.5的贡献平均为1.7 μg m−3（约占PM的50-80%）。在城市和城市背景区的测量站也可以看到轻轨PM的影响。然而，由于城市地区的局部排放较大，轻轨PM的比例不太明显（占PM的36-50%）。
Elevated particulate matter concentrations due to Asian long-range transport (LRT) are frequently observed in the free troposphere (FT) above the Pacific Northwest, U.S. Transport of this aerosol from the FT to the boundary layer (BL) and its effect to local air quality remain poorly constrained. We used data collected at the Mount Bachelor observatory (MBO, 2.8 km a.s.l) and from ground stations in the Pacific Northwest to study transport of fine particulate matter (PM) from the FT to the BL. During Asian LRT episodes PM concentrations were clearly elevated above the corresponding monthly averages at MBO as well as at low elevation sites across Washington and Oregon. Also, a clear correlation between MBO and low elevation sites was observed, indicating that LRT episodes are seen in both the FT and BL. In addition, drum impactor measurements show that the chemical composition of PM at MBO was similar to that measured at the BL sites. Using a simple regression model, we estimate that during springtime, when the transport from Asia is most effective, the contribution of Asian sources to PM2.5in clean background areas of the Pacific Northwest was on average 1.7 μg m−3(representing approximately 50–80% of PM). The influence of LRT PM was also seen in measurement stations situated in the urban and urban background areas. However, the fraction of LRT PM was less pronounced (36–50% of PM) due to larger local emissions in the urban areas.