Water‐soluble organic compounds in biomass burning aerosols over Amazonia 2. Apportionment of the chemical composition and importance of the polyacidic fraction
Water‐soluble organic compounds in biomass burning aerosols over Amazonia 2. Apportionment of the chemical composition and importance of the polyacidic fraction
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DOI：
10.1029/2001jd000522
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发表时间：
2002-10
影响因子：
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通讯作者：
O. Mayol-Bracero;P. Guyon;B. Graham;Gregory Charles Roberts;M. Andreae;S. Decesari;M. Facchini;
中科院分区：
文献类型：
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作者：
O. Mayol-Bracero;P. Guyon;B. Graham;Gregory Charles Roberts;M. Andreae;S. Decesari;M. Facchini;
[1]对来自巴西亚马逊地区Rondonia的碳质气溶胶进行了化学表征，这是欧洲对亚马逊地区大规模生物圈-大气实验（LBA-EUSTACH）的一部分贡献。采样期（1999年10月）包括燃烧季高峰和干湿季过渡。采用热燃烧法对碳质材料进行表征。这使得气溶胶总碳（TC）、黑碳（BC）和有机碳（OC）的测定成为可能。相当一部分BC材料（平均约50%）似乎是可溶于水的高度难熔的有机材料。对水溶性有机碳（WSOC）组分进行了更详细的分析，包括WSOC含量的测定，水溶性组分的高效液相色谱（HPLC）分离（紫外检测），以及单个组分的气相色谱/质谱（GC/MS）表征。WSOC组分占OC的45 ~ 75%。高WSOC分数表明气溶胶主要来自闷烧燃烧。通过GC/MS，检测到许多不同的化合物，包括羟基、羧酸盐和羰基。GC/MS鉴定的WSOC含量约为10%。通过HPLC/UV分离出中性化合物(N)、单羧酸和二羧酸（MDA）和多羧酸（PA）三类化合物。这三个类群的总和约占WSOC的70%，其中MDA和PA含量最多（约占50%）。BCwater（水提后的BC）和左旋葡聚糖（均为生物质燃烧指标）与水溶性物质（即WSOC、N、MDA和PA）呈良好的相关性（r2在0.84 ~ 0.99之间），且在燃烧期间其浓度的增加有力地证明了生物质燃烧是WSOC的主要来源。特别有趣的是，PA和类似腐殖质的物质（由于它们的多酸性）在生物质燃烧过程中大量产生。这些物质由于其水溶性和表面张力降低效应，可能在确定生物质燃烧气溶胶的整体云凝结核活性方面发挥重要作用，因此在云过程和气候强迫中可能很重要。
[1] Chemical characterization was performed on carbonaceous aerosols from Rondonia in the Brazilian Amazon region as part of the European contribution to the Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA-EUSTACH). The sampling period (October 1999) included the peak of the burning season as well as the dry-to-wet season transition. Characterization of the carbonaceous material was performed by using a thermal combustion method. This enabled determination of aerosol total carbon (TC), black carbon (BC), and organic carbon (OC). A significant fraction of the BC material (on average about 50%) seemed to be highly refractory organic material soluble in water. A more detailed analysis of the water-soluble organic carbon (WSOC) fraction of the TC was undertaken, involving measurements of WSOC content, high-performance liquid chromatography (HPLC) separation (with UV detection) of the water-soluble components, and characterization of individual components by gas chromatography/mass spectrometry (GC/MS). The WSOC fraction accounted for 45−75% of the OC. This high WSOC fraction suggests an aerosol derived mainly from smoldering combustion. Using GC/MS, many different compounds, containing hydroxy, carboxylate, and carbonyl groups, were detected. The fraction of the WSOC identified by GC/MS was about 10%. Three classes of compounds were separated by HPLC/UV: neutral compounds (N), monocarboxylic and dicarboxylic acids (MDA), and polycarboxylic acids (PA). The sum of these three groups accounted for about 70% of the WSOC, with MDA and PA being most abundant (about 50%). Good correlations (r2 between 0.84 and 0.99) of BCwater (BC after water extraction) and levoglucosan (both indicators of biomass combustion) with the water-soluble species (i.e., WSOC, N, MDA, and PA), and their increase in concentrations during the burning period provided strong evidence that biomass burning is a major source of the WSOC. Particularly interesting is that PA and therefore, probably, humic-like substances (due to their polyacidic nature) are generated in significant amounts during biomass burning. These substances, due to their water solubility and surface tension-lowering effects, may play an important role in determining the overall cloud condensation nuclei activity of biomass burning aerosols and, consequently, could be important in cloud processes and climate forcing.