Hygroscopic behavior of water-soluble matter extracted from biomass burning aerosols collected at a rural site in Tanzania, East Africa
Hygroscopic behavior of water-soluble matter extracted from biomass burning aerosols collected at a rural site in Tanzania, East Africa
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DOI：
10.1002/2014jd021546
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发表时间：
2014-11-16
影响因子：
4.4
通讯作者：
Fu, Pingqing
中科院分区：
文献类型：
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作者：
Boreddy, S. K. R.;Kawamura, Kimitaka;Fu, Pingqing
在这项研究中，我们提出了从生物质燃烧衍生的颗粒物2.5（PM2.5）气溶胶中提取的水溶性物质（WSM）的吸湿行为，收集在坦桑尼亚的农村背景站点在2011年6月至8月。通过吸湿串联微分迁移率分析仪（H-TDMA）测量WSM的吸湿生长因子g（RH），其中初始干颗粒直径为100 nm。我们观察到，在90%相对湿度（RH）下，WSM的g（RH），g（90%）（WSM），范围为1.10至1.47，平均值为1.25 +/- 0.12。H-TDMA检索的WSM吸湿性参数kappa（WSM）范围为0.04 - 0.24，平均值为0.11 +/- 0.07。我们发现，所观察到的g（90%）（WSM）与PM2.5中K+（R-2 = 0.61），Cl-（0.54）和有机碳（0.58）的质量分数呈正相关。此外，它与左旋葡聚糖（0.67）和总二酸（0.76），这意味着，虽然无机部分可能是最重要的因素，以控制吸湿性，生物质燃烧有机物在坦桑尼亚气溶胶的吸湿性发挥了重要作用。在采样点获得的较低的生长因子可能是由于在大气老化过程中形成了水溶性较低的草酸钾（K2 C2 O 4）或吸湿性较低的K2 SO 4颗粒。我们观察到一个中等的相关性（R-2 = 0.33）之间的PM2.5质量分数的WSOC和g（90%）（WSM）。检索的g（90%）（WSOM）值范围为1.0 - 1.25，平均值为1.16 +/- 0.05。这项研究表明，坦桑尼亚气溶胶的吸湿性在很大程度上是由生物质燃烧产品的排放和随后的化学老化过程中大气传输控制。
In this study, we present the hygroscopic behavior of water-soluble matter (WSM) extracted from biomass burning derived particulate matter 2.5 (PM2.5) aerosols collected at a rural background site in Tanzania during June-August 2011. Hygroscopic growth factors, g(RH), of WSM were measured by hygroscopic tandem differential mobility analyzer (H-TDMA) with an initial dry particle diameter of 100 nm. We observed that the g(RH) of WSM at 90% relative humidity (RH), g(90%)(WSM), ranged from 1.10 to 1.47 with an average of 1.25 +/- 0.12. The H-TDMA retrieved hygroscopicity parameter of WSM, kappa(WSM), ranged from 0.04 to 0.24 with a mean of 0.11 +/- 0.07. We found that the observed g(90%)(WSM) is positively correlated with PM2.5 mass fractions of K+ (R-2 = 0.61), Cl- (0.54), and organic carbon (0.58). Moreover, it well correlates with levoglucosan (0.67) and total diacids (0.76), implying that although the inorganic fraction may be the most important factor to control the hygroscopicity; biomass burning organics play a significant role in the hygroscopicity of Tanzanian aerosols. The lower growth factors obtained over the sampling site are probably due to the formation of less water-soluble potassium oxalate (K2C2O4) or less hygroscopic K2SO4 particles during atmospheric aging. We observed a moderate correlation (R-2 = 0.33) between PM2.5 mass fraction of WSOC and g(90%)(WSM). The retrieved g(90%)(WSOM) values ranged from 1.0 to 1.25 with a mean of 1.16 +/- 0.05. This study demonstrates that the hygroscopicity of Tanzanian aerosols is largely controlled by the emission of biomass burning products and the subsequent chemical aging during atmospheric transport.