Composition and diurnal variability of the natural Amazonian aerosol
Composition and diurnal variability of the natural Amazonian aerosol
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DOI：
10.1029/2003jd004049
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发表时间：
2003-12-18
影响因子：
4.4
通讯作者：
Andreae, MO
中科院分区：
文献类型：
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作者：
Graham, B;Guyon, P;Andreae, MO
作为亚马逊河流域大规模生物圈-大气实验（LBA）-合作LBA空中区域实验（CLAIRE）2001年活动的一部分，2001年7月在巴西亚马逊河流域的一个地面站点分别采集了白天和夜间气溶胶样本，以研究自然“背景”气溶胶的组成和时间变化。分析技术的组合被用来表征气溶胶的元素和离子组成。通过电子显微镜和光学显微镜鉴定了大于0.5 mm的主要颗粒类型。粗粒和细粒气溶胶都主要由有机物组成（质量百分比分别为70%和80%），粗粒部分含有少量土壤尘埃和海盐颗粒，细粒部分含有一些非海盐硫酸盐。粗颗粒物质量浓度（CPM近似于PM10 - PM2）在夜间最高（平均值= 3.9 +/- 1.4 mg m（-3），平均昼夜比= 1.9 +/- 0.4），而细颗粒物质量浓度（FPM近似于PM2）在白天增加（平均值= 2.6 +/- 0.8 mg m（-3），平均夜-日比= 0.7 +/- 0.1）。在CPM夜间增加恰逢初级生物颗粒在此大小范围内（主要是酵母菌和其他真菌孢子）的增加，导致从表面衍生的森林气溶胶下的浅夜间边界层和湖陆微风效应在现场的陷阱，虽然活跃的夜间孢子形成也可能作出了贡献。与此相关，我们观察到夜间浓度升高的生物元素和离子（P，S，K，Cu，Zn，NH 4+）的CPM部分。对于FPM部分持续较高的白天浓度的有机碳被发现，这表明，光化学生产的二次有机气溶胶从生物挥发性有机化合物可能作出了显着的贡献，细气溶胶。灰尘和海盐相关的元素/离子的CPM部分，和非海盐硫酸盐的FPM部分，显示较高的白天浓度，最有可能是由于增强对流向下混合的远程传输气溶胶。
As part of the Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA)-Cooperative LBA Airborne Regional Experiment (CLAIRE) 2001 campaign, separate day and nighttime aerosol samples were collected in July 2001 at a ground-based site in Amazonia, Brazil, in order to examine the composition and temporal variability of the natural "background'' aerosol. A combination of analytical techniques was used to characterize the elemental and ionic composition of the aerosol. Major particle types larger than similar to0.5 mm were identified by electron and light microscopy. Both the coarse and fine aerosol were found to consist primarily of organic matter (similar to70 and 80% by mass, respectively), with the coarse fraction containing small amounts of soil dust and sea-salt particles and the fine fraction containing some non-sea-salt sulfate. Coarse particulate mass concentrations (CPM approximate to PM10 - PM2) were found to be highest at night (average = 3.9 +/- 1.4 mg m(-3), mean night-to-day ratio = 1.9 +/- 0.4), while fine particulate mass concentrations (FPM approximate to PM2) increased during the daytime (average = 2.6 +/- 0.8 mg m(-3), mean night-to-day ratio = 0.7 +/- 0.1). The nocturnal increase in CPM coincided with an increase in primary biological particles in this size range (predominantly yeasts and other fungal spores), resulting from the trapping of surface-derived forest aerosol under a shallow nocturnal boundary layer and a lake-land breeze effect at the site, although active nocturnal sporulation may have also contributed. Associated with this, we observed elevated nighttime concentrations of biogenic elements and ions (P, S, K, Cu, Zn, NH4+) in the CPM fraction. For the FPM fraction a persistently higher daytime concentration of organic carbon was found, which indicates that photochemical production of secondary organic aerosol from biogenic volatile organic compounds may have made a significant contribution to the fine aerosol. Dust and sea-salt-associated elements/ions in the CPM fraction, and non-sea-salt sulfate in the FPM fraction, showed higher daytime concentrations, most likely due to enhanced convective downward mixing of long-range transported aerosol.