Separation of brown carbon from black carbon for IMPROVE and Chemical Speciation Network PM2.5 samples
Separation of brown carbon from black carbon for IMPROVE and Chemical Speciation Network PM2.5 samples
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DOI：
10.1080/10962247.2018.1426653
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发表时间：
2018-01-01
影响因子：
2.7
通讯作者：
Gronstal, Steven B.
中科院分区：
文献类型：
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作者：
Chow, Judith C.;Watson, John G.;Gronstal, Steven B.
用 2015 型热/光分析仪 (TOA) 替换沙漠研究所 (DRI) 2001 型，可实现长期有机碳 (OC) 和元素碳 (EC) 数据库的连续性，并且无需额外的碳分析工作即可添加光学信息。多波长光衰减的价值在于，可以将黑碳 (BC) 的光吸收与棕碳 (BrC) 的光吸收分开，随后归因于已知来源，例如生物质燃烧和二次有机气溶胶。有证据表明，根据光衰减与 EC 的比率，过滤器负载对 EC 浓度最高的所有样品中的 25% 产生影响。需要研究类似于七波长测温计所使用的负载校正。平均而言，非城市受保护视觉环境机构间监测 (IMPROVE) 样本显示出比城市化学形态网络 (CSN) 样本更高的短波长吸收 BrC 分数，这是由于生物质燃烧和老化气溶胶的影响更大，以及城市发动机排气中的初级 BC 贡献更高。在大沼泽地国家公园野火期间采集的连续样本展示了从明火燃烧到阴燃燃烧的演变，随着阴燃开始主导火灾事件，BrC 分数增加。含义：在对特定 PM2.5（空气动力学直径为 2.5 m 的颗粒物）样本进行热/光学碳分析时纳入七个波长，可以估计生物质燃烧和二次有机气溶胶的贡献。这种分离对于评估控制策略的有效性、识别异常事件和确定自然能见度条件很有用。
The replacement of the Desert Research Institute (DRI) model 2001 with model 2015 thermal/optical analyzers (TOAs) results in continuity of the long-term organic carbon (OC) and elemental carbon (EC) database, and it adds optical information with no additional carbon analysis effort. The value of multiwavelength light attenuation is that light absorption due to black carbon (BC) can be separated from that of brown carbon (BrC), with subsequent attribution to known sources such as biomass burning and secondary organic aerosols. There is evidence of filter loading effects for the 25% of all samples with the highest EC concentrations based on the ratio of light attenuation to EC. Loading corrections similar to those used for the seven-wavelength aethalometer need to be investigated. On average, nonurban Interagency Monitoring of PROtected Visual Environments (IMPROVE) samples show higher BrC fractions of short-wavelength absorption than urban Chemical Speciation Network (CSN) samples, owing to greater influence from biomass burning and aged aerosols, as well as to higher primary BC contributions from engine exhaust at urban sites. Sequential samples taken during an Everglades National Park wildfire demonstrate the evolution from flaming to smoldering combustion, with the BrC fraction increasing as smoldering begins to dominate the fire event.Implications: The inclusion of seven wavelengths in thermal/optical carbon analysis of speciated PM2.5 (particulate matter with an aerodynamic diameter 2.5 m) samples allows contributions from biomass burning and secondary organic aerosols to be estimated. This separation is useful for evaluating control strategy effectiveness, identifying exceptional events, and determining natural visibility conditions.