Properties and evolution of biomass burning organic aerosol from Canadian boreal forest fires
Properties and evolution of biomass burning organic aerosol from Canadian boreal forest fires
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DOI：
10.5194/acp-15-3077-2015
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发表时间：
2014-10
影响因子：
6.3
通讯作者：
Matthew D. Jolleys;H. Coe;G. Mcfiggans;Jonathan W. Taylor;S. O'Shea;M. Breton;S. Bauguitte;S. Molle
中科院分区：
文献类型：
--
作者：
Matthew D. Jolleys;H. Coe;G. Mcfiggans;Jonathan W. Taylor;S. O'Shea;M. Breton;S. Bauguitte;S. Molle
对北方森林火灾生物质燃烧有机气溶胶（BBOA）的空中测量揭示了不同年龄羽流的高度对比特性。这些测量使用Aerodyne Research Inc.小型飞行时间气溶胶质量流量计（C-ToF-AMS）在BORTAS期间（使用飞机和卫星定量北方森林火灾对大西洋上空对流层氧化剂的影响）实验，已用于推导归一化过量有机气溶胶（OA）质量浓度（1 OA =1CO），与更高的平均比率观察到更接近源（0.190 0.010）比在远场（0.097 0.002）。新鲜烟羽和老化烟羽之间1 OA =1CO的差异受整个燃烧过程中主要燃烧条件变化的影响。在一次研究飞行中，对火源的测量包括3次羽流拦截，并对大部分闷烧的火进行了采样。在远场的四次飞行中进行了23次拦截，羽流来自于活动早期发生的火灾，当时火灾活动更为激烈，在与老化相关的任何转变之前，排放量形成了潜在的对比。燃烧条件的变化也会影响生物质燃烧排放物的垂直分布，因为来自火焰占主导地位的火灾的老化羽流被注入到高达6000 m的更高海拔。AMS质谱中质荷比（m/z/ 60和44峰）对总OA质量（表示为f60和f44/）的比例贡献分别用作初级和氧化BBOA的示踪剂。f44在近场羽流中的平均值低于在远场中取样的值，这与羽流被传输到距源更远的距离时的更长的老化时间一致。然而，1 O3 =1CO和log（NOx= NOy/接近源的高水平表明排放物可以在短时间内非常快速地氧化。相反，进入对流层上部的羽流的放样可以导致源廓线在广泛的时间和空间尺度上传输后的保留，在老化的羽流中平均f60也更高。OA成分随年龄的变化与先前研究中BB示踪剂的观察结果相当，显示从f60到f44的持续进展。老化羽流中氧合水平升高及其与1 OA =1CO平均值较低的相关性与老化期间由于稀释和化学处理的结合而通过蒸发造成的OA损失一致，而整个活动中燃烧条件的差异也对BBOA的产生和组成有显著影响。
Airborne measurements of biomass burning or- ganic aerosol (BBOA) from boreal forest fires reveal highly contrasting properties for plumes of different ages. These measurements, performed using an Aerodyne Re- search Inc. compact time-of-flight aerosol mass spectrom- eter (C-ToF-AMS) during the BORTAS (quantifying the impact of BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellites) experiment in the summer of 2011, have been used to derive nor- malised excess organic aerosol (OA) mass concentrations (1OA=1CO), with higher average ratios observed closer to source (0.190 0.010) than in the far-field (0.097 0.002). The difference in 1OA=1CO between fresh and aged plumes is influenced by a change in dominant combus- tion conditions throughout the campaign. Measurements at source comprised 3 plume interceptions during a single re- search flight and sampled largely smouldering fires. Twenty- three interceptions were made across four flights in the far- field, with plumes originating from fires occurring earlier in the campaign when fire activity had been more intense, cre- ating an underlying contrast in emissions prior to any trans- formations associated with aging. Changing combustion con- ditions also affect the vertical distribution of biomass burn- ing emissions, as aged plumes from more flaming-dominated fires are injected to higher altitudes of up to 6000 m. Pro- portional contributions of the mass-to-charge ratio (m/z/ 60 and 44 peaks in the AMS mass spectra to the total OA mass (denoted f60 and f44/ are used as tracers for primary and oxidised BBOA, respectively. f44 is lower on average in near-field plumes than those sampled in the far-field, in accordance with longer aging times as plumes are trans- ported a greater distance from source. However, high levels of 1O3=1CO and log(NOx= NOy/ close to source indi- cate that emissions can be subject to very rapid oxidation over short timescales. Conversely, the lofting of plumes into the upper troposphere can lead to the retention of source pro- files after transportation over extensive temporal and spatial scales, withf60 also higher on average in aged plumes. Evo- lution of OA composition with aging is comparable to obser- vations of BB tracers in previous studies, revealing a consis- tent progression fromf60 tof44. The elevated levels of oxy- genation in aged plumes, and their association with lower average 1OA=1CO, are consistent with OA loss through evaporation during aging due to a combination of dilution and chemical processing, while differences in combustion conditions throughout the campaign also have a significant influence on BBOA production and composition.