| Summary: | 碩士 === 國立中央大學 === 化學學系 === 103 === This study is to develop a mobile laboratory and a diagnostic methodology involving the use of proton-transfer reaction mass spectrometry (PTR-MS) to investigate chemical pollutants released from industrial parks. The establishment is expected to remedy the lack of detecting capabilities of toxic or odorous compounds in existing EPA air-quality and photochemical monitoring stations (PAMS). This study used two types of PTR-MS, quadrupole mass spectrometry (dubbed PTR-QMS) and time-of-flight mass spectrometry (dubbed PTR-TOF/MS) to analyze ambient volatile organic compounds (VOCs) released from industrial parks.
In cope with the large datasets accumulating overtime, box-whisker plotting and snowball data sampling methods were adopted for rapid data screening to facilitate rapid identification of key compounds. With the use of the high mass resolving power (m/Δ= 5000) of PTR-TOF/MS and the chemical database, key VOCs unique to specific pollution sources can be accurately identified. Furthermore, the combined use of concentration variability and field wind data helped interpret the source-and-receptor relationship of pollution events.
Field measurements targeting emissions from Hsinchu Far-East Chemical Fiber Plant, Pingjhen Industrial Park and Mailiao Industrial Park revealed that the majority of the measured VOCs were oxygenated (OVOCs). In the Pingjhen measurement, the trigger-sampling technique was coupled with PTR-QMS to capture plume events from the factory cluster. The triggered samples were analyzed for 108 VOCs by in-lab GC/MS/FID (gas chromatography/mass spectrometry/flame ionization detector) to characterize the chemical composition of the pollution plumes. The results showed that OVOCs accounted for 16% -75% of the total amount of 108 VOCs in Pingjhen (compared to 15% - 60% in Hsinchu and 32% - 84% in Chungli). Such large fractions of OVOCs in the air may explain the frequent odor complaints reported in the vicinity of the industrial parks. Moreover, large emissions of OVOCs may contribute to the production of photochemical ozone.
In addition to OVOCs, nitrogen containing VOCs (NVOCs) were also found in the cases of Hsinchu Far East Chemical Fiber Plant and Pingjhen Industrial Park. Dimethylformamide (DMF) and morpholine were the two prominent NVOCs that are suspected to strongly link with foul odors plaguing neighboring communities.
By exploiting the high data resolution of PTR-MS measurements, concentration spikes were often link to the meteorological conditions. For instance, in the case of the Hsinchu Far Eastern Chemical Fiber Plant, abrupt rise in concentrations were found to associate with poor atmospheric dispersion conditions as well as the change in wind speed/direction. In the coastal areas, such as Mailiao Industrial Park and Kaohsiung (city), the concentrations were significantly affected by the seasonal sea-land breeze, the subtle change of wind made selected VOCs varied from below sub-ppb to hundreds of ppb or even ppm levels.
|
|---|
