VOCs走航监测:技术方法与案例应用

挥发性有机物(VOCs)来源广泛、组成复杂,是臭氧(O3)和二次有机气溶胶(SOA)的重要前体物,且其中一些组分对人体健康存在潜在威胁。VOCs的主要排放方式包括点源、面源和无组织源排放,排放过程具有瞬时性,难以控制和监测。与传统的离线监测和在线监测相比,走航监测技术具有监测范围大、响应快速、机动性强的特点,但中国VOCs的走航监测研究还鲜有报道。该研究通过使用装载了单质谱分析仪与便携式气相色谱-质谱联用仪(GC-MS)的走航车对珠三角沿海城市某工业集聚区进行VOCs走航监测,走航过程中对环境空气中的TVOCs进行快速监测并对TVOCs质量浓度高值点进行采样及VOCs组分的成分和浓度分析。该次走航共监测到32种优控污染因子和CW加油(加气)站、JH加油站、G空调电器生产企业的两器车间及南门货场等多个TVOCs质量浓度高值点,并通过分析进一步判断VOCs排放源。结合监测结果和实地调研推断:加油站的VOCs高值主要来源于油气挥发及机动车尾气排放;G空调企业的VOCs高值则主要来源于两器车间的喷涂、烘干、洗网工序及厂区内的机动车尾气排放。尽管VOCs走航监测技术目前还存在一定不足,该方法的应用能够为掌握区域VOCs污染现状及分布特征提供新的技术手段,为实现VOCs精细化管控提供新的思路。

VOCs Cruise Monitoring: Technical Method and Case Application

Volatile organic compounds(VOCs) are important precursors of ozone(O3) and secondary organic aerosols(SOA) due to their wide sources and complex composition. Some of the VOCs pose potential threats to human health. The main emission sources of VOCs include point sources, non-point sources and non-organized sources. The emission process of VOCs is instantaneous and difficult to control and monitor. Cruise monitoring technology overcomes the shortcomings of traditional off-line monitoring and on-line monitoring, and has the characteristics of large monitoring range, fast response and strong maneuverability. However, there are few related studies on VOCs cruise monitoring in China at present. This study monitored the VOCs in an industrial agglomeration area in the coastal city of the Pearl River Delta by using a vehicle loaded with a single mass spectrometer and a portable gas chromatography-mass spectrometry(GC-MS). TVOCs in environmental air were monitored on-line and VOCs samples were collected and analyzed at the places with high TVOCs values. Totally 32 kinds of prior control pollutants were detected, and several places with high TVOCs concentrations were monitored, including CW filling station, JH gas station, two-unit workshop and south-gate freight yard of G air conditioner manufacturing enterprise. Combined with the monitoring results and field research, it is concluded that the high TVOCs values at gas stations mainly comes from the volatilization of oil and gas and the exhaust emission of motor vehicles;the high TVOCs values at G air conditioning enterprise mainly comes from the spraying, drying and net washing processes in the workshop and the exhaust emission of motor vehicles in the factory. The application of VOCs cruise monitoring technology provides a new technique for grasping the present situation and distribution characteristics of VOCs pollution in the region and helps realizing the refined control of VOCs, although it still has some shortcomings at present.