许天峰,马嫣,郑军,蒋友凌.2019年秋季南京北郊气溶胶光学特性研究[J].环境科学学报,2021,41(11):4353-4365
2019年秋季南京北郊气溶胶光学特性研究
- Aerosol optical properties in northern suburbs of Nanjing during autumn of 2019
- 基金项目：国家自然科学基金（No.41975172，41730106）
- 许天峰
- 1. 南京信息工程大学环境科学与工程学院, 南京 210044;2. 江苏省大气环境与监测污染控制高技术研究重点实验室, 南京 210044
- 马嫣
- 1. 南京信息工程大学环境科学与工程学院, 南京 210044;2. 江苏省大气环境与监测污染控制高技术研究重点实验室, 南京 210044
- 郑军
- 1. 南京信息工程大学环境科学与工程学院, 南京 210044;2. 江苏省大气环境与监测污染控制高技术研究重点实验室, 南京 210044
- 蒋友凌
- 1. 南京信息工程大学环境科学与工程学院, 南京 210044;2. 江苏省大气环境与监测污染控制高技术研究重点实验室, 南京 210044
- 摘要：于2019年11月1日-12月4日在南京北郊对气溶胶光学特性进行观测研究，使用三波长光声黑碳光谱仪（PASS-3）对气溶胶吸收系数βabs和散射系数βsca进行了实时在线观测.结果表明，532 nm处的βabs和βsca平均值分别为（31.58±16.84）Mm-1和（168.46±127.09）Mm-1，均低于南京以往的观测值.βabs和βsca的日变化呈双峰型，早晚高峰均与交通排放有关.除早晚高峰以外，βsca在13：00-14：00略有回升，这与二次气溶胶的生成有关.本次观测期间气溶胶吸收系数和散射系数在风向为东风、东南风和西风时易出现高值，东风、东南风时受到本地排放的影响，西风时受到外地污染物传输的影响，气溶胶的消光物质主要集中在细粒子上.对观测期间典型污染过程的分析表明，高湿度、低风速的不利扩散条件下本地污染排放与西北向污染气团传输的叠加，使得气溶胶吸收系数和散射系数出现连续高值.吸收系数主要受交通排放影响，而工业源和交通源排放的SO2、NOx等气态污染物经过大气光化学氧化或液相氧化形成的二次气溶胶及其吸湿增长是导致散射系数增强的主要原因.
- Abstract：Measurements on aerosol optical properties were carried out at Nanjing University of Information Science and Technology in the northern suburbs of Nanjing from November 1st to December 4th, 2019. The absorption (βabs) and scattering coefficients (βsca) are observed by using a three-wavelength photoacoustic soot spectrometer (PASS-3) in real time. Our results showed that the averaged βabs and βsca at 532 nm were (31.58±16.84) Mm-1 and (168.46±127.09) Mm-1, respectively, which were much lower than the values previously observed in Nanjing. The diurnal variations of both βabs and βsca are bimodal, and peaks in the morning and evening time are related to traffic emissions during rush hour. Besides, aerosol scattering are seen increased from 13:00 to 14:00 at noon due to the formation of secondary aerosols. During our observation, strong absorption and scattering tend to happen with existence of easterly, southeasterly and westerly winds. The enhancement of light extinction was mostly contributed by local emissions when the winds are from east and southeast, whereas contaminant transport was dominant when the winds are from west. The light extinction matter is concentrated mainly on fine particles. Through case study, continuous strong light extinction were found caused by combination of local pollution and contaminant transport from northwest under high RH and low wind speed conditions. The enhancement of βabs was related to traffic emissions, while the enhancement of βsca was possibly due to the formation and subsequent hygroscopic growth of secondary aerosols from photochemical or aqueous-phase oxidation of SO2 and NOx from industrial and traffic source.
