| 济南市夏季典型臭氧污染过程VOCs组分特征及来源分析 |
| 摘要点击 1137 全文点击 286 投稿时间：2023-07-05 修订日期：2023-09-17 |
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| 中文关键词 臭氧（O3） 挥发性有机物（VOCs） 来源解析 污染过程 OBM模型 |
| 英文关键词 ozone （O3） volatile organic compounds （VOCs） source analysis pollution process OBM model |
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| 中文摘要 |
| 基于2021年6月16~26日济南市一次典型臭氧（O3）污染过程,结合107种VOCs监测数据,以山区背景点做参照,分析了市区在不同污染时期（清洁期CP、污染上升期PRP、重污染期HPP和污染下降期PDP）O3及其前体物挥发性有机物（VOCs）的变化特征,并运用正定矩阵因子分解模型（PMF）和箱式模型（OBM）识别VOCs的主要来源和O3生成机制及敏感性物种. 结果表明,市区HPP期ρ（O3-8h）均值为（246.67±11.24）μg·m-3, ρ（O3-1h）峰值为300 μg·m-3,VOCs体积分数和NO2浓度受边界层高度和风速降低影响,分别高出其它3个时期76.99%~145.36%和127.78%~141.18%,是O3污染加重的主要原因. 市区VOCs中烷烃、含氧挥发性有机物（OVOCs）和卤代烃占比较大,为43.81%、20.98%和17.43%,三者在HPP期增长明显,丙酮、丙烷和乙烷各时期均为体积分数前3物种,异戊烷HPP期增长最多；臭氧生成潜势（OFP）占比较大的有烯烃、烷烃和芳香烃,为40.19%、28.06%和21.92%,1-丁烯、甲苯、异戊烷和异戊二烯是OFP较高的物种,异戊二烯在PRP期最高,除此以外均为1-丁烯最高,异戊烷HPP期受体积分数影响OFP明显升高. VOCs与CO相关系数初步表明机动车尾气与油气挥发是HPP期VOCs主要来源,进一步采用PMF发现溶剂使用源、燃烧源、机动车尾气+油气挥发源、工业排放源和植物源是市区VOCs的重要来源,其中HPP期机动车尾气+油气挥发源对VOCs的贡献高出其他时期3.09~14.72倍,溶剂使用源对VOCs的贡献是CP期和PRP期的2.50倍左右,说明机动车尾气+油气挥发源和溶剂使用源是造成VOCs体积分数增长的主要来源. 潜在源和浓度权重分析发现VOCs还受东北方向滨州和东营传输的影响. OBM结果表明,市区O3生成主要路径为过氧化羟基自由基（HO2·）和甲基过氧自由基（CH3O2·）两者与NO反应,HPP期臭氧净生成速率[P（O3）net]为24×10-9 h-1,敏感性实验表明O3生成对VOCs中的烯烃组分最敏感,1-丁烯、丙烯、顺-2-丁烯和乙烯是O3生成的优控物种. |
| 英文摘要 |
| Based on a typical ozone （O3） pollution process in Jinan City from June 16 to 26, 2021, the variation characteristics of O3 and its precursor volatile organic compounds （VOCs） during different pollution periods （clean period （CP）, pollution rise period （PRP）, heavy pollution period （HPP）, and pollution decline period （PDP）） in the urban area were analyzed. Both positive matrix factorization （PMF） and an observation-based model （OBM） were used to identify the main sources of VOCs, O3 production mechanisms, and sensitive species. The results showed that the average value of ρ（O3-8h） during the HPP period in the urban area was （246.67±11.24） μg·m-3, and ρ（O3-1h） had a peak value of 300 μg·m-3. The volume fractions of VOCs and NO2 concentration were affected by the decrease in planetary boundary layer and wind speed, which were 76.99%-145.36% and 127.78%-141.18% higher than those in the other three periods, respectively, and were the main reasons for the aggravation of O3 pollution. Alkanes, oxygenated volatile organic compounds （OVOCs）, and halogenated hydrocarbons accounted for 43.81%, 20.98%, and 17.43% of VOCs in urban areas, respectively. All of them showed significant growth during the HPP period, with acetone, propane, and ethane being the top three species by volume in each stage and isopentane showing the highest growth during the HPP period. Alkene, alkanes, and aromatic hydrocarbons accounted for 40.19%, 28.06%, and 21.92% of the ozone generation potential （OFP）. 1-butene, toluene, isopentane, and isoprene were the species with higher OFP. Isoprene had the highest OFP during the PRP phase, and 1-butene had the highest OFP during the HPP phase. The volume fraction of isopentane significantly increased OFP. The correlation coefficient between VOCs and CO preliminarily indicated that motor vehicle exhaust and oil and gas volatilization were the main sources of VOCs during the HPP period. Further use of PMF revealed that solvent use sources, combustion sources, motor vehicle exhaust+oil and gas volatilization sources, industrial emission sources, and plant sources were important sources of VOCs in urban areas. The contribution of motor vehicle exhaust+oil and gas volatilization sources in the HPP period to VOCs was 3.09-14.72 times higher than that in other periods. The contribution of solvent use sources to VOCs was approximately 2.50 times higher than that in the CP and PRP periods. The main sources of VOCs volume fraction increase were motor vehicle exhaust, oil and gas volatilization sources, and solvent use sources. Potential sources and concentration weight analysis found that VOCs were also affected by the transmission of VOCs to Binzhou and Dongying in the northeast direction. The OBM results indicated that the main pathway of O3 formation in urban areas was the reaction of peroxide hydroxyl radicals （HO2·） and methyl peroxide radicals （CH3O2·） with NO, and the net ozone generation rate during the HPP phase [P（O3）net] was 24×10-9 h-1. Based on the sensitivity experiment results, the alkene components of 1-butene, propylene, cis-2-butene, and ethylene were the dominant species for O3 production. |
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