Radney James G, You Rian, Zachariah Michael R, Zangmeister Christopher D
Material Measurement Laboratory, National Institute of Standards and Technology , Gaithersburg, Maryland 20899, United States.
Department of Chemistry and Biochemistry, University of Maryland , College Park, Maryland 20742, United States.
Environ Sci Technol. 2017 May 16;51(10):5622-5629. doi: 10.1021/acs.est.7b00810. Epub 2017 May 4.
Particles from smoldering biomass burning (BB) represent a major source of carbonaceous aerosol in the terrestrial atmosphere. In this study, mass specific absorption spectra of laboratory-generated smoldering wood particles (SWP) from 3 hardwood and 3 softwood species were measured in situ. Absorption data spanning from λ = 500 to 840 nm were collected using a photoacoustic spectrometer coupled to a supercontinuum laser with a tunable wavelength and bandwidth filter. SWP were size- (electrical mobility) and mass-selected prior to optical characterization allowing data to be reported as mass-specific absorption cross sections (MAC). The median measured MAC at λ = 660 nm for smoldering oak particles was 1.1 (0.57/1.8) × 10 m g spanning from 83 femtograms (fg) to 517 fg (500 nm ≤ mobility diameter ≤950 nm), MAC values in parentheses are the 16 and 84 percentiles of the measured data (i.e., 1σ). The collection of all six wood species (Oak, Hickory, Mesquite, Western redcedar, Baldcypress, and Blue spruce) had median MAC values ranging from 1.4 × 10 m g to 7.9 × 10 m g at λ = 550 nm with absorption Ångström exponents (AAE) between 3.5 and 6.2. Oak, Western redcedar, and Blue spruce possessed statistically similar (p > 0.05) spectra while the spectra of Hickory, Mesquite, and Baldcypress were distinct (p < 0.01) as calculated from a point-by-point analysis using the Wilcox rank-sum test.
闷烧生物质燃烧（BB）产生的颗粒物是陆地大气中碳质气溶胶的主要来源。在本研究中，对实验室生成的来自3种硬木和3种软木的闷烧木材颗粒（SWP）的质量比吸收光谱进行了原位测量。使用与具有可调波长和带宽滤波器的超连续激光耦合的光声光谱仪收集了波长范围从λ = 500至840 nm的吸收数据。在进行光学表征之前，对SWP进行了尺寸（电迁移率）和质量选择，从而能够将数据报告为质量比吸收截面（MAC）。闷烧橡木颗粒在λ = 660 nm处测得的MAC中位数为1.1(0.57/1.8)×10 m²/g，粒径范围从83飞克（fg）至517 fg（500 nm≤迁移直径≤950 nm），括号中的MAC值是测量数据的第16和第84百分位数（即1σ）。所有六种木材（橡木、山核桃木、牧豆树、西部红雪松、落羽杉和蓝云杉）在λ = 550 nm处的MAC中位数范围为1.4×10⁻⁶ m²/g至7.9×10⁻⁶ m²/g，吸收Ångström指数（AAE）在3.5至6.2之间。根据使用Wilcox秩和检验的逐点分析计算，橡木、西部红雪松和蓝云杉具有统计学上相似的（p>0.05）光谱，而山核桃木、牧豆树和落羽杉的光谱则明显不同（p<0.01）。
