Lee Yong Hwan, Choi Yongjoo, Ghim Young Sung
Department of Environmental Science, Hankuk University of Foreign Studies, Yongin, 17035, South Korea.
Present address: Department of Air Quality Research, National Institute of Environmental Research, Incheon, 22689, South Korea.
Environ Sci Pollut Res Int. 2016 May;23(9):8917-28. doi: 10.1007/s11356-016-6125-3. Epub 2016 Jan 28.
The inorganic ions in PM2.5 were measured downwind of metropolitan Seoul using a particle-into-liquid sampler over three periods. Five diurnal patterns, including a low-concentration pattern (L) and a high-concentration pattern with a decreasing trend during the day (H-), were distinguished for the first period from February to June 2012. The sum of ion concentrations increased primarily due to NO3 (-) with decreasing temperature and increasing relative humidity, which caused preferential partitioning of NO3 (-) into the particulate phase. The peak concentration occurred during the morning rush hour for L but was delayed until the next morning for H- due to the time required to form secondary inorganic ions from accumulated pollutants under lower wind speeds. The characteristic features of the patterns observed during the first period were generally similar with those obtained for the other two periods. However, for the second period, comprised of colder months, changes in the diurnal patterns from L to H- were accompanied by increasing temperature, as the effect of photochemical formation of NO3 (-) was larger than that of volatilization. Although the role of long-range transport was not distinct on the whole, the inflow of air masses from cleaner sectors was observed to lower the concentrations.
在三个时间段内，使用颗粒-液体采样器对首尔大都市区下风处的PM2.5中的无机离子进行了测量。在2012年2月至6月的第一个时间段内，区分出了五种日变化模式，包括低浓度模式（L）和白天呈下降趋势的高浓度模式（H-）。离子浓度总和的增加主要归因于NO3（-），这是由于温度降低和相对湿度增加，导致NO3（-）优先分配到颗粒相中。L模式的峰值浓度出现在早高峰时段，而H-模式的峰值浓度则推迟到第二天早上，这是因为在较低风速下，累积污染物形成二次无机离子需要时间。在第一个时间段内观察到的模式特征通常与其他两个时间段获得的特征相似。然而，在由较冷月份组成的第二个时间段内，日变化模式从L变为H-伴随着温度升高，因为NO3（-）的光化学形成作用大于挥发作用。尽管总体上远距离传输的作用并不明显，但观察到来自较清洁区域的气团流入会降低浓度。
