Application of the constrained CLS and the synthetic background generation method to the ambient ozone and VOCs concentrations

초록

The volatile organic carbons play an important role in determining the photo-chemical oxidant concentrations such as ozone through complex interaction with nitrogen oxides. Although the sampling method using Gas Chromatography is able to resolve the volatile organic carbons accurately, the temporal and spatial resolutions is often not sufficient for understanding the mechanisms associated with the high oxidant phenomena. The required temporal and spatial resolutions can be achieved by the OP-FTIR but the detection limit of the OP-FTIR limits its application to the ambient conditions considerably. The newly developed spectrum analysis method named as CLSB, which enhances the accuracy and detection limit considerably to allow the measurement of the ambient chemical species concentrations, was implemented here to determine the various chemical species including alkanes, alkenes, acetone, ozone, ammonia, CO in the urban area. The results showed that the OP-FTIR measured ozone, water, alkanes and acetones agree quite well with the GC results but the OP-FTIR measured alkene concentrations are one order of magnitude higher than the GC measured values.