Measurement of NO_(2), SO_(2), O_(3) and HNO_(2) Concentrations with a Long-Path Differential Optical Absorption Spectrometer (LP-DOAS) in Kwangju, Korea.

摘要

Optical measurement of gaseous air pollutants by open-path monitoring technique provides higher resolution and sensitivity than conventional point monitoring methods. A Long-Path Differential Optical Absorption Spectroscopy (LP-DOAS) system, which consists of a coaxial telescope, retro-reflector, optical fiber, spectrometer, and analyzer, has been developed. A 150W Xenon arc lamp is employed as a light source. For recording the absorption spectra, a spectrometer with holographic gratings and a 1024 channel photodiode array detector was adopted. Concentrations of trace gas species in the beam's path were determined simultaneously by the procedure of least squares fit to a linear function of reference absorption spectra of trace gases from the measured differential absorption spectra. Concentrations of trace air pollutants such as NO_(2), SO_(2), O_(3), and HNO_(2) were measured in the UV region (290-350 nm) over a 1.5km beam path by the K-JIST LP-DOAS system during an intensive measurement period of 12-22 March, 2002 in Kwangju, Korea. The average mixing ratios in trace gas species were observed to be 10.1, 2.0, 18.7, and 0.6 ppbv for NO_(2), SO_(2), O_(3), and HNO_(2), respectively during the measurement period.