Characteristics of PM2.5 and its chemical constituents in Seoul, Taipei, and Kanazawa

Abstract

PM2.5 samples were collected at two urban monitoring sites in Seoul, Taipei, and at one rural monitoring site in Kanazawa. The sampling site in Seoul was located on the roof of the School of Public Health building at Seoul National University (37.5° N, 127.0° E) in Seoul, Korea, and the site of Taipei was located on the roof of Gu-ting elementary school (25.0°N, 121.3° E) in Taipei, Taiwan. The measurements of Kanazawa were made on the roof of the School of Pharmaceutical and Health Science building at Kanazawa University (36.3° N, 136.4° E) in Kanazawa, Japan. Samples were collected from midnight to midnight (00:00 ~ 24:00) mostly every third day (Seoul: from April 2010 - May 2013, Taipei: December 2010 - May 2013, Kanazawa: November 2011 - May 2013). The PM2.5 and chemical speciated samples were collected using a 3-channel system for 24-hour. The system had one channel using an Annular Denuder System (ADS) and two channels using filter packs (URG Corp.). The PM2.5 mass concentrations were 37, 36, and 25 ㎍/㎥ in Seoul, Taipei, and Kanazawa, respectively. The measured chemical constituents were carbonaceous species such as organic carbon (OC) and elemental carbon (EC), ion species including nitrate (NO3-), sulfate (SO42-), ammonium (NH4+), and trace elements. Sulfate was the highest in both Taipei (9.90 ㎍/㎥) and Kanazawa (7.35 ㎍/㎥), while nitrate was highest in Seoul (9.31 ㎍/㎥). Backward trajectories were calculated using Hybrid Single-particle Lagrangian Integrated Trajectory (HYSPLIT) 4 model and Potential Source Contribution Function (PSCF) model was applied to identify the possible source locations of carbonaceous and ionic species. PSCF results showed that the possible source locations of most chemical constituents measured in Seoul were the industrial areas in the eastern coast, middle regions of China, and the Gobi Desert. In Taipei, PSCF results identified the southern part of China and South-East Asia as the possible source areas. Kanazawa was mostly affected by eastern coastal region of China, southern part of Korea, and the Pacific Ocean.