Multi-wavelength optical measurement to enhance thermal/optical analysis for carbonaceous aerosol
Multi-wavelength optical measurement to enhance thermal/optical analysis for carbonaceous aerosol
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DOI：
10.5194/amt-8-451-2015
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发表时间：
2015-01-01
影响因子：
3.8
通讯作者：
Watson, J. G.
中科院分区：
文献类型：
--
作者：
Chen, L. -W. A.;Chow, J. C.;Watson, J. G.
配备有用于监测过滤器样品的光谱反射率（R）和透射率（T）的七波长光源/检测器（405-980 nm）的热/光学碳分析仪允许“热光谱分析（TSA）”和波长（λ）依赖的有机碳（OC）元素碳（EC）测量。光学感测用可追溯到绝对R和T测量的转移标准进行校准，针对负载效应进行调整以报告光谱光吸收（作为吸收光学深度（τ（α，λ），并使用柴油机排气样品进行验证。对环境和源样品的测试表明，当基于相同的波长（类似于635 nm）进行热解调节时，OC和EC浓度与常规碳分析的浓度相当。TSA提供了额外的信息，评估黑碳（BC）和棕碳（BrC）的贡献及其在太阳光谱的近红外到近紫外部分的光学特性。增强型碳分析仪可以为当前的气溶胶监测计划增加价值，并为气候，能见度或健康研究提供更准确的OC和EC测量。
A thermal/optical carbon analyzer equipped with seven-wavelength light source/detector (405-980 nm) for monitoring spectral reflectance (R) and transmittance (T) of filter samples allowed "thermal spectral analysis (TSA)" and wavelength (lambda)-dependent organic-carbon (OC)-elemental-carbon (EC) measurements. Optical sensing was calibrated with transfer standards traceable to absolute R and T measurements, adjusted for loading effects to report spectral light absorption (as absorption optical depth (tau(a,lambda))), and verified using diesel exhaust samples. Tests on ambient and source samples show OC and EC concentrations equivalent to those from conventional carbon analysis when based on the same wavelength (similar to 635 nm) for pyrolysis adjustment. TSA provides additional information that evaluates black-carbon (BC) and brown-carbon (BrC) contributions and their optical properties in the near infrared to the near ultraviolet parts of the solar spectrum. The enhanced carbon analyzer can add value to current aerosol monitoring programs and provide insight into more accurate OC and EC measurements for climate, visibility, or health studies.