Inter-Comparisons of Major Ions and Organic Matter Using Aerodyne Aerosol Mass Spectrometer, Ion Chromatography and Sunset Lab Carbon Analyzer in Aged Aerosols from Okinawa in the Western North Pacific Rim
oleh: Bhagawati Kunwar, Kazuhiro Torii, Akinori Takami, Kimitaka Kawamura
| Format: | Article |
|---|---|
| Diterbitkan: | MDPI AG 2022-12-01 |
Deskripsi
Inorganic components were measured in the aged ambient aerosols from Cape Hedo, Okinawa, an outflow region of East Asia, using online quadrupole Aerodyne aerosol mass spectrometer (Q-AMS) and offline ion chromatography (IC) and Sunset Lab carbon analyzer. Here, we performed an inter-comparison study on nitrate (NO<sub>3</sub><sup>−</sup>), ammonium (NH<sub>4</sub><sup>+</sup>) and sulfate (SO<sub>4</sub><sup>2−</sup>) that were measured by IC and AMS. Sulfate and ammonium showed a good agreement between two instruments. However, abundances of NO<sub>3</sub><sup>−</sup> by AMS are on average twice overestimated compared to nitrate obtained by IC. We also found that a significant amount of organic nitrogen (ON) was detected in the filter samples from Okinawa. The online measurement (Q-AMS) data and offline filter based-NO<sub>3</sub><sup>−</sup> data need to be carefully evaluated when ON is abundantly present in aerosols. The OM/OC ratios derived from AMS are consistent with the bulk OM<sub>AMS</sub>/OC<sub>Sunset</sub> ratios (2.1). This study demonstrates that the OM/OC of 2.1 is the reasonable criteria for more aged aerosols.