Influence of Ambient Atmospheric Environments on the Mixing State and Source of Oxalate-Containing Particles at Coastal and Suburban Sites in North China

• Published in: Atmosphere 2022-05, Vol.13 (5), p.647
• Main Authors: Zhao, Yunhui, Zhang, Yanjing, Li, Xiaodong, Li, Lei, Feng, Limin, Xie, Huan, Li, Wenshuai, Liu, Xiaohuan, Zhu, Yujiao, Sheng, Lifang, Qi, Jianhua, Gao, Huiwang, Zhou, Zhen, Zhou, Yang
• Format: Article
• Language: English
• Subjects: Atmospheric aerosols; Atmospheric models; Biodegradation; Biomass burning; Burning; coastal site; Combustion; Copper; Decay rate; Emissions; Environmental degradation; Fuel oils; Heavy metals; Industrial emissions; Iron; Lasers; Mass spectrometry; Mass spectroscopy; Metals; Moisture content; oxalate; oxalate-Fe; Oxalic acid; Particle decay; Photodegradation; Residual fuel oil; Scientific imaging; single-particle; suburban site; Sunrise; VOCs; Volatile organic compounds; Water content; Zinc
• ISSN: 2073-4433; 2073-4433
• DOI: 10.3390/atmos13050647

Photodegradation is a key process impacting the lifetime of oxalate in the atmosphere, but few studies investigated this process in the field due to the complex mixing and sources of oxalate. Oxalate-containing particles were measured via single-particle aerosol mass spectrometry at coastal and suburban sites in Qingdao, a coastal city in North China in the summer of 2016. The mixing state and influence of different ambient conditions on the source and photodegradation of oxalate were investigated. Generally, 6.3% and 12.3% of the total particles (by number) contained oxalate at coastal and suburban sites, respectively. Twelve major types of oxalate-containing particles were identified, and they were classified into three groups. Biomass burning (BB)-related oxalate–K and oxalate–carbonaceous particles were the dominant groups, respectively, accounting for 68.9% and 13.6% at the coastal site and 72.0% and 16.8% at the suburban site. Oxalate–Heavy metals (HM)-related particles represented 14.6% and 9.3% of the oxalate particles at coastal and suburban sites, respectively, which were mainly from industrial emissions (Cu-rich, Fe-rich, Pb-rich), BB (Zn-rich), and residual fuel oil combustion (V-rich). The peak area of oxalate at the coastal site decreased immediately after sunrise, while it increased during the daytime at the suburban site. However, the oxalate peak area of Fe-rich particles at both sites decreased after sunrise, indicating that iron plays an important role in oxalate degradation in both environments. The decay rates (k) of Fe-rich and BB-Fe particles at the coastal site (−0.978 and −0.859 h−1, respectively), were greater than those at the suburban site (−0.512 and −0.178 h−1, respectively), owing to the high-water content of particles and fewer oxalate precursors. The estimated k values of oxalate peak area for different ambient conditions were in the same order of magnitude, which can help establish or validate the future atmospheric models.