Chemical characterization of water-soluble organic carbon aerosols at a rural site in the Pearl River Delta, China, in the summer of 2006
Chemical characterization of water-soluble organic carbon aerosols at a rural site in the Pearl River Delta, China, in the summer of 2006
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DOI：
10.1029/2009jd011736
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发表时间：
2009-07-31
影响因子：
4.4
通讯作者：
Weber, R. J.
中科院分区：
文献类型：
--
作者：
Miyazaki, Y.;Kondo, Y.;Weber, R. J.
2006年7月，在珠江三角洲的一个农村地区，中国使用颗粒入液采样器(PILS)和总有机碳(TOC)分析仪相结合的方法在线测量了水溶性有机碳(WSOC)气溶胶。用大孔非离子(DAX-8)树脂对亲水性和疏水性WSOC进行了定量，WSOC分别被定义为穿透DAX-8柱和保留在DAX-8柱上的WSOC组分。实验室标定表明，亲水性WSOC(WSOCHPI)包括低分子脂肪族二元酸和羰基、糖和胺，而疏水性WSOC(WSOCHPO)包括较长链脂肪族二元酸和羰基、芳香酸、酚类、有机硝酸盐、环酸和黄腐酸。WSOC总量(TWSOC)占有机碳总量的60%，WSOCHPO占TWSOC总量的60%。WSOCHPI和WSOCHPO都随光化学老化而增加，由NOx/NOY比值确定。特别是，发现WSOCHPO的平均质量在类似于10小时的时间尺度内增加了5倍，大大大于WSOCHPI的增加(2-3倍)。随着光化学老化，有机碳质量的总体增加与WSOCHPO质量的大幅增加有关。这些结果与实验室校准相结合，表明大量疏水有机化合物(可能含有大量碳数)是通过光化学处理产生的。相比之下，水不溶性有机碳(WIOC)的质量没有随光化学老化而表现出明显的变化，这表明在研究期间，WIOC向WSOC的化学转化不是产生WSOC的主要过程。
Online measurements of water-soluble organic carbon (WSOC) aerosols were made using a particle-into-liquid sampler (PILS) combined with a total organic carbon (TOC) analyzer at a rural site in the Pearl River Delta region, China, in July 2006. A macroporous nonionic (DAX-8) resin was used to quantify hydrophilic and hydrophobic WSOC, which are defined as the fractions of WSOC that penetrated through and retained on the DAX-8 column, respectively. Laboratory calibrations showed that hydrophilic WSOC (WSOCHPI) included low-molecular aliphatic dicarboxylic acids and carbonyls, saccharides, and amines, while hydrophobic WSOC (WSOCHPO) included longer-chain aliphatic dicarboxylic acids and carbonyls, aromatic acids, phenols, organic nitrates, cyclic acids, and fulvic acids. On average, total WSOC (TWSOC) accounted for 60% of OC, and WSOCHPO accounted for 60% of TWSOC. Both WSOCHPI and WSOCHPO increased with photochemical aging determined from the NOx/NOy ratio. In particular, the average WSOCHPO mass was found to increase by a factor of five within a timescale of similar to 10 hours, which was substantially larger than that of WSOCHPI (by a factor of 2-3). The total increase in OC mass with photochemical aging was associated with the large increase in WSOCHPO mass. These results, combined with the laboratory calibrations, suggest that significant amounts of hydrophobic organic compounds (likely containing large carbon numbers) were produced by photochemical processing. By contrast, water-insoluble OC (WIOC) mass did not exhibit significant changes with photochemical aging, suggesting that chemical transformation of WIOC to WSOC was not a dominant process for the production of WSOC during the study period.