Ground-based aerosol characterization during the South American Biomass Burning Analysis (SAMBBA) field experiment
Ground-based aerosol characterization during the South American Biomass Burning Analysis (SAMBBA) field experiment
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DOI：
10.5194/acp-14-12069-2014
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发表时间：
2014-01-01
影响因子：
6.3
通讯作者：
Artaxo, P.
中科院分区：
文献类型：
--
作者：
Brito, J.;Rizzo, L. V.;Artaxo, P.
本文研究了受生物质燃烧严重影响的地面气溶胶的物理和化学特征。该站点位于巴西亚马逊雨林西南部朗的韦略港附近，被选中部署一套大型仪器，其中包括气溶胶化学形态监测仪。我们的测量是在南美生物质燃烧分析（SAMBBA）现场实验期间进行的，该实验包括巴西上空的飞机和地面测量，旨在调查生物质燃烧排放对气候，空气质量和数值天气预报的影响。该活动在2012年9月/10月的旱季和雨季过渡期间进行。在活动的大部分时间内，该场地受到区域生物质燃烧污染（平均CO混合比为0.6 ppm）的影响，偶尔会叠加强烈（高达2 ppm的CO）的新排放生物质燃烧羽流。气溶胶数浓度范围从接近1000 cm-3到高达35000 cm-3的峰值（在生物质燃烧（BB）事件期间，对应于平均亚微米质量平均浓度为13.7 μ g m-3，峰值浓度接近100 μ g m-3）。有机气溶胶在亚微米非耐火成分中占主导地位，平均浓度为11.4 μ g m（-3）。观察到的无机物NH 4、SO 4、NO3和Cl的平均浓度分别为0.44、0.34、0.19和0.01 μ g m（-3）。当量黑碳（BCe）范围为0.2至5.5 μ g m（-3），平均浓度为1.3 μ g m（-3）。在BB峰期间，有机物占总质量的90%以上（亚微米非耐火材料加上BCe），在文献中描述的最高值中。我们使用H：C和O：C比率的变化来检查生物质燃烧有机气溶胶（BBOA）的老化，并且发现在大多数气溶胶处理过程中，（O：C与D 0：25一致至O：C与D 0：6一致），H：C比未观察到显著变化（类似于1：35）。这一结果与以前对城市和亚马逊河流域生物气溶胶化学老化的观察形成强烈对比。在较高的处理水平（O：C > 0：6）下，H：C比率以H：C / O：C斜率为-0.5的方式变化，这可能是由于BB（H：C / O：C斜率D 0）和生物（H：C / O：C斜率D1）有机气溶胶（OA）的组合的发展。Δ OA /Δ CO质量比的分析产生非常小的增强OA加载与大气处理，与以前的观察结果一致。这些结果表明，可以忽略不计的二次有机气溶胶（SOA）的形成发生在整个观察到的BB羽流处理，或SOA的形成几乎完全平衡的OA volatility.Positive基质因子分解（PMF）的有机气溶胶光谱的三个因素：新鲜的BBOA，老化的BBOA，和低挥发性含氧有机气溶胶（LV-OOA）。日变化模式和与外部标志物的相关性分析表明，在运动的第一部分，OA浓度的影响，当地的火羽流与一些化学处理发生在近地层。在运动的第二部分，长距离运输的BB羽流以上的表面层，以及潜在的SOA形成高空，占主导地位的OA浓度在我们的地面采样site.This手稿描述了第一个地面部署的气溶胶质谱在亚马逊地区的生物质燃烧严重影响的网站，使气溶胶生命周期在这个重要的生态系统的更深入的了解。
This paper investigates the physical and chemical characteristics of aerosols at ground level at a site heavily impacted by biomass burning. The site is located near Porto Velho, Rondonia, in the southwestern part of the Brazilian Amazon rainforest, and was selected for the deployment of a large suite of instruments, among them an Aerosol Chemical Speciation Monitor. Our measurements were made during the South American Biomass Burning Analysis (SAMBBA) field experiment, which consisted of a combination of aircraft and ground-based measurements over Brazil, aimed to investigate the impacts of biomass burning emissions on climate, air quality, and numerical weather prediction over South America. The campaign took place during the dry season and the transition to the wet season in September/October 2012.During most of the campaign, the site was impacted by regional biomass burning pollution (average CO mixing ratio of 0.6 ppm), occasionally superimposed by intense (up to 2 ppm of CO), freshly emitted biomass burning plumes. Aerosol number concentrations ranged from similar to 1000 cm(-3) to peaks of up to 35 000 cm(-3) (during biomass burning (BB) events, corresponding to an average submicron mass mean concentrations of 13.7 mu g m(-3) and peak concentrations close to 100 mu g m-3. Organic aerosol strongly dominated the submicron non-refractory composition, with an average concen-tration of 11.4 mu g m(-3). The inorganic species, NH4, SO4, NO3, and Cl, were observed, on average, at concentrations of 0.44, 0.34, 0.19, and 0.01 mu g m(-3), respectively. Equivalent black carbon (BCe) ranged from 0.2 to 5.5 mu g m(-3), with an average concentration of 1.3 mu g m(-3). During BB peaks, organics accounted for over 90% of total mass (submicron non-refractory plus BCe), among the highest values described in the literature.We examined the ageing of biomass burning organic aerosol (BBOA) using the changes in the H : C and O : C ratios, and found that throughout most of the aerosol processing (O : C congruent to D 0 : 25 to O : C congruent to D 0 : 6), no remarkable change is observed in the H : C ratio (similar to 1 : 35). Such a result contrasts strongly with previous observations of chemical ageing of both urban and Amazonian biogenic aerosols. At higher levels of processing (O : C > 0 : 6), the H : C ratio changes with a H : C / O : C slope of -0.5, possibly due to the development of a combination of BB (H : C / O : C slope D 0) and biogenic (H : C / O : C slope D 1) organic aerosol (OA). An analysis of the Delta OA / Delta CO mass ratios yields very little enhancement in the OA loading with atmospheric processing, consistent with previous observations. These results indicate that negligible secondary organic aerosol (SOA) formation occurs throughout the observed BB plume processing, or that SOA formation is almost entirely balanced by OA volatilization.Positive matrix factorization (PMF) of the organic aerosol spectra resulted in three factors: fresh BBOA, aged BBOA, and low-volatility oxygenated organic aerosol (LV-OOA). Analysis of the diurnal patterns and correlation with external markers indicates that during the first part of the campaign, OA concentrations are impacted by local fire plumes with some chemical processing occurring in the near-surface layer. During the second part of the campaign, long-range transport of BB plumes above the surface layer, as well as potential SOAs formed aloft, dominates OA concentrations at our ground-based sampling site.This manuscript describes the first ground-based deployment of the aerosol mass spectrometry at a site heavily impacted by biomass burning in the Amazon region, allowing a deeper understanding of aerosol life cycle in this important ecosystem.