青岛市夏季VOCs污染特征及来源解析

于2020年7月1—31日在山东省青岛市开展VOCs在线监测,对VOCs浓度、污染特征、反应活性及来源进行分析。结果表明:2020年青岛市夏季VOCs浓度为(24.78±11.69)×10^-9,其中烷烃浓度占比最大(44.79%),醛酮(21.98%)和卤代烃(16.85%)次之;烯烃对臭氧生成潜势(OFP)和羟基反应速率(L_·OH)的贡献较大,分别为37.10%和55.63%,丁烯、正丁烷和丙烯为对OFP和L_·OH贡献较高的3类物种。使用正矩阵因子分解(PMF)模型对VOCs进行了来源解析,识别出5个来源,包括液化石油气(LPG)/二次生成源(31.1%)、固定燃烧源(22.6%)、移动源(20.6%)、橡塑生产源(18.1%)和工业溶剂源(7.6%),LPG使用是青岛市大气VOCs的控制要点。后向气流轨迹聚类结果表明,青岛市夏季主要受省内城市气团、东北方向远距离海上气团、东—东南方向海上气团的影响,其中来自省内的短程气团对青岛本地VOCs浓度贡献最大。

Characteristics and source analysis of VOCs pollution in summer in Qingdao

VOCs online monitoring was carried out in Qingdao City, Shandong Province from July 1 to 31, 2020, and the concentration, pollution characteristics, reactive activity and source of VOCs were analyzed. The results showed that the concentration of VOCs in summer of 2020 was (24.78±11.69)×10-9, of which alkanes accounted for the largest content (44.79%), followed by aldehydes and ketones (21.98%) and halogenated hydrocarbons (16.85%). The results of atmospheric chemical reactivity of VOCs showed that alkenes contributed the most to ozone formation potential (OFP) and hydroxyl reaction rate (L·OH), accounting for 37.10% and 55.63%, respectively. Butene, n-butane and propylene were the three species with the highest contribution to OFP and L·OH. Positive matrix factorization (PMF) model was used to analyze the sources of VOCs, and five sources were identified, including liquefied petroleum gas (LPG) /secondary generation source (31.1%), fixed combustion source (22.6%), mobile source (20.6%), rubber and plastic production source (18.1%) and industrial solvent source (7.6%). The use of LPG was the key point of atmospheric VOCs control in Qingdao. The clustering results of backward airflow trajectories showed that Qingdao was mainly affected by the provincial urban air masses, the long-distance maritime air masses in the northeast, and maritime air masses in the east-southeast direction in summer. The short-range air masses from the province made the largest contribution to the local VOCs concentration in Qingdao.