Abstract A lack of information on the radiative effects of refractory black carbon (rBC) emitted from biomass burning is a significant gap in our understanding of climate change. A custom-made combustion chamber was used to simulate the open burning of crop residues and investigate the impacts of rBC size and mixing state on the particles' optical properties. Average rBC mass median diameters ranged from 141 to 162 nm for the rBC produced from different types of crop residues. The number fraction of thickly-coated rBC varied from 53 to 64%, suggesting that a majority of the freshly emitted rBC were internally mixed. By comparing the result of observed mass absorption cross-section to that calculated with Mie theory, large light absorption enhancement factors (1.7–1.9) were found for coated particles relative to uncoated cores. These effects were strongly positively correlated with the percentage of coated particles but independent of rBC core size. We suggest that rBC from open biomass burning may have strong impact on air pollution and radiative forcing immediately after their production.

中文翻译：

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由于新鲜生物质燃烧排放物中黑碳的混合状态，增强了光吸收

摘要 缺乏关于生物质燃烧排放的难熔黑碳 (rBC) 辐射效应的信息是我们对气候变化理解的一个重大空白。使用定制的燃烧室来模拟作物残留物的露天燃烧，并研究 rBC 尺寸和混合状态对颗粒光学特性的影响。对于由不同类型作物残留物产生的 rBC，平均 rBC 质量中值直径范围为 141 至 162 nm。厚涂层 rBC 的数量分数从 53% 到 64% 不等，这表明大部分新排放的 rBC 是内部混合的。通过将观察到的质量吸收截面的结果与 Mie 理论计算的结果进行比较，发现相对于未涂覆的核，涂覆颗粒的光吸收增强因子较大（1.7-1.9）。这些影响与包覆颗粒的百分比呈强正相关，但与 rBC 核心尺寸无关。我们认为，来自露天生物质燃烧的 rBC 可能对空气污染和产生后立即产生的辐射强迫产生强烈影响。