Biomass burning (BB) is an important contributor to the air pollution in Southeast Asia (SEA), but the emission sources remain great uncertainty. In this study, PM_2.5 samples were collected from an urban (Chiang Mai University, CMU) and a rural (Nong Tao village, NT) site in Chiang Mai, Thailand from February to April (high BB season, HBB) and from June to September (low BB season, LBB) in 2018. Source apportionment of carbonaceous aerosols was carried out by Latin Hypercube Sampling (LHS) method incorporating the radiocarbon (¹⁴C) and organic markers (e.g., dehydrated sugars, aromatic acids, etc.). Thereby, carbonaceous aerosols were divided into the fossil-derived elemental carbon (EC_f), BB-derived EC (EC_bb), fossil-derived primary and secondary organic carbon (POC_f, SOC_f), BB-derived OC (OC_bb) and the remaining OC (OC_{nf, other}). The fractions of EC_bb generally prevailed over EC_f throughout the year. OC_bb was the dominant contributor to total carbon with a clear seasonal trend (65.5 ± 5.8 % at CMU and 79.9 ± 7.6 % at NT in HBB, and 39.1 ± 7.9 % and 42.8 ± 4.6 % in LBB). The distribution of POC_f showed a spatial difference with a higher contribution at CMU, while SOC_f displayed a temporal variation with a greater fraction in LBB. OC_{nf, other} was originated from biogenic secondary aerosols, cooking emissions and bioaerosols as resolved by the principal component analysis with multiple liner regression model. The OC_{nf, other} contributed within a narrow range of 6.6 %-14.4 %, despite 34.9 ± 7.9 % at NT in LBB. Our results highlight the dominance of BB-derived fractions in carbonaceous aerosols in HBB, and call the attention to the higher production of SOC in LBB.

生物质燃烧（BB）是东南亚（SEA）空气污染的重要贡献者，但排放源仍然存在很大的不确定性。在这项研究中，PM _2.5样本是从 2 月至 4 月（高 BB 季节，HBB）和 6 月至2018年9月（BB淡季，LBB）。采用拉丁超立方采样（LHS）方法，结合放射性碳（¹⁴ C）和有机标记物（如脱水糖、芳香酸等）对碳质气溶胶进行来源解析。由此，碳质气溶胶分为化石源元素碳（EC _f）、BB源EC（EC _bb）、化石源原生有机碳和次生有机碳（POC _f、SOC _f）、BB源OC（OC _bb ) 和剩余的 OC (OC _{nf, other} )。全年EC _bb的分数总体上优于 EC _{f 。}OC _bb是总碳的主要贡献者，具有明显的季节性趋势（HBB 中 CMU 为 65.5 ± 5.8 %，NT 为 79.9 ± 7.6 %，LBB 为 39.1 ± 7.9 % 和 42.8 ± 4.6 %）。_{POC f}的分布表现出空间差异，在 CMU 中贡献较高，而 SOC _f表现出时间变化，在 LBB 中贡献较大。OC _{nf, other}源自生物二次气溶胶、烹饪排放物和生物气溶胶，通过多元线性回归模型的主成分分析来解决。OC _nf、其他贡献在 6.6 %-14.4 % 的狭窄范围内，尽管 LBB 中 NT 为 34.9 ± 7.9 %。我们的结果强调了 HBB 中碳质气溶胶中 BB 衍生组分的主导地位，并引起人们对 LBB 中 SOC 较高产量的关注。