Desert Research Institute, Reno, NV, USA; University of California, Berkeley, CA, USA.
Desert Research Institute, Reno, NV, USA.
Sci Total Environ. 2023 Apr 20;870:161857. doi: 10.1016/j.scitotenv.2023.161857. Epub 2023 Jan 30.
Atmospheric polycyclic aromatic hydrocarbons (PAHs) can be emitted from different combustion sources including domestic biomass burning, internal combustion engines, and biomass burning (BB) in wild, prescribed, and agricultural fires. With climate warming and consequent global increases in frequency and severity of wildfires, BB is a dominant source of PAHs emitted into the atmosphere. In this study, six globally and regionally important and representative fuels (Alaskan peat, Moscow peat, Pskov peat, eucalyptus, Malaysian peat, and Malaysian agricultural peat) were burned under controlled conditions in the combustion chamber facility at the Desert Research Institute (DRI, Reno, NV, USA). Gas- and particle-phase BB emissions were aged in an oxidation flow reactor (OFR) to mimic five to sevendays of atmospheric aging. To sample gas- and particle-phase BB emissions, fresh and OFR-aged biomass-burning aerosols were collected on Teflon-impregnated glass fiber filters (TIGF) in tandem with XAD resin media for organic carbon speciation. The objectives of this study were to i) quantify the emission factors for 113 PAHs emitted from the combustion of the six selected fuels, ii) characterize the distribution of PAH compounds between gas and particle phases for these fuels, iii) identify the changes in PAHs during OFR-aging, and iv) evaluate toxicity potential with characterized compounds. We found that combustion emissions of gas-phase PAHs were more abundant (>80 % by mass) than particle-phase PAHs, for emissions from all combusted fuels. The mass fraction of substituted napthalenes in Moscow peat and Malaysian peat emissions were ∼70 % & 84 %, respectively, whereas in Eucalyptus the same fraction was <50 %, which indicates that these substituted compounds can be used as tracers for peat emissions. Mass concentrations of gas- and particle-phase PAHs were reduced by ∼70 % after OFR oxidation. However, the understanding of the fate of PAHs during OFR oxidation requires further investigations. Our results also indicate that the PAH toxicity of BB samples would be underestimated by 10-100 times if only the BaP for the 16 US EPA priority PAHs in the particle phase are included.
大气多环芳烃 (PAHs) 可以由不同的燃烧源排放，包括家庭生物质燃烧、内燃机和野外、规定和农业火灾中的生物质燃烧 (BB)。随着气候变暖以及随之而来的野火发生频率和严重程度的增加，BB 是大气中排放的 PAHs 的主要来源。在这项研究中，六种在全球和区域范围内重要且具有代表性的燃料（阿拉斯加泥炭、莫斯科泥炭、普斯科夫泥炭、桉树、马来西亚泥炭和马来西亚农业泥炭）在位于美国内华达州里诺市的沙漠研究所（DRI）的燃烧室设施中进行了受控燃烧。在氧化流动反应器（OFR）中对气体和颗粒相的 BB 排放物进行老化，以模拟 5 至 7 天的大气老化。为了采集气体和颗粒相的 BB 排放物，新鲜和 OFR 老化的生物质燃烧气溶胶在 Teflon 浸渍玻璃纤维过滤器（TIGF）上与 XAD 树脂介质一起收集，用于有机碳形态分析。本研究的目的是：i）量化从六种选定燃料的燃烧中排放的 113 种 PAHs 的排放因子，ii）对这些燃料的气相和颗粒相之间 PAH 化合物的分布进行特征描述，iii）确定 OFR 老化过程中 PAHs 的变化，iv）用特征化合物评估毒性潜力。我们发现，对于所有燃烧的燃料，气相 PAHs 的燃烧排放量（质量超过 80%）大于颗粒相 PAHs 的排放量。莫斯科泥炭和马来西亚泥炭排放物中取代萘的质量分数分别约为 70%和 84%，而桉树中相同分数小于 50%，这表明这些取代化合物可用作泥炭排放物的示踪剂。OFR 氧化后，气相和颗粒相 PAHs 的质量浓度降低了约 70%。然而，OFR 氧化过程中 PAHs 命运的理解还需要进一步的研究。我们的研究结果还表明，如果仅将颗粒相中 16 种美国环保署优先 PAHs 的 BaP 包括在内，BB 样品的 PAH 毒性将被低估 10-100 倍。
