To understand the characteristics and sources of organic aerosols (OA) in North China, we studied diacids, oxoacids, and α‐dicarbonyls in summer‐ and winter‐time fine aerosols (PM_2.5) collected from Tianjin. Oxalic (C₂) acid was found to be the most abundant diacid species, followed by succinic (C₄), malonic (C₃), and sebacic (C₈) acids, respectively. Glyoxylic (ωC₂) was the most abundant oxoacids followed by pyruvic acid. Concentrations of total diacids, oxoacids, and α‐dicarbonyls in winter were 2–3 times higher than those in summer, but their mass fractions in PM_2.5 were exactly the opposite. On average, total diacids carbon accounted for 2.9% in total carbon and 3.3% in organic carbon (OC) in summer and 1.8% and 2.0%, respectively, in winter. Their contributions to water‐soluble OC (WSOC) was almost the same in both seasons (5.5% and 5.3%, respectively). Molecular distributions, mass ratios of selected diacid (C₃, C₄, M, F, C₆, Ph, and C₉) species, and the linear relations among the selected species (including ∑C₂–C₄ and ∑C₈–C₁₂) and with inorganic markers (K⁺ and SO₄²⁻) implied that the diacids and related compounds are mainly originated from coal combustion and biomass burning emissions and produced in the atmosphere by both in situ photochemical reactions at local scale and aging during long‐range transport in both summer and winter. This study revealed that diacids and related compounds and WSOC are increased with increasing SO₄²⁻ and they are produced in the aqueous phase, implying that the reduction in NO_x and SO₂ emissions could possibly control the water‐soluble OA loading over North China.

中文翻译：

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华北天津夏季和冬季精细气溶胶中二酸，含氧酸和α-二羰基的分子分布：燃烧源和水相二次形成的排放

为了了解华北地区的有机气溶胶（OA）的特征和来源，我们研究了从天津采集的夏季和冬季的精细气溶胶（PM _2.5）中的二酸，含氧酸和α-二羰基。发现草酸（C ₂）是最丰富的二酸种类，其次是琥珀酸（C ₄），丙二酸（C ₃）和癸二酸（C ₈）。乙醛酸（ω c ^ ₂）是最丰富的含氧酸，随后丙酮酸。冬季总二酸，含氧酸和α-二羰基的浓度比夏季高2-3倍，但它们的质量分数在PM _2.5中恰恰相反。平均而言，夏季的二酸总碳分别占总碳的2.9％和有机碳（OC）的3.3％，冬季分别占1.8％和2.0％。在两个季节中，它们对水溶性OC（WSOC）的贡献几乎相同（分别为5.5％和5.3％）。分子分布，选定二酸质量比（C ₃，C ₄，M，F，C ₆中，Ph，和C ₉）种，并且所选择的种（包括ΣC之间的线性关系₂ -C ₄和ΣC ₈ –C ₁₂）和无机标记（K ⁺和SO ₄ ²⁻）暗示二酸和相关化合物主要源自煤炭燃烧和生物质燃烧排放物，并通过局部规模的原位光化学反应和夏季和冬季的长期运输过程中的老化在大气中产生。这项研究表明，二酸和相关化合物以及WSOC随着SO ₄ ^2−的增加而增加，并且它们是在水相中产生的，这表明NO _x和SO ₂排放量的减少可能会控制华北地区水溶性OA的负载量。 。