THESIS
2022
1 online resource (xiii, 66 pages) : color illustrations, color maps
Abstract
As a highly urbanized city in East Asia, Hong Kong has suffered from severe ozone (O
3) pollution for many years. A comprehensive understanding of the current pollution characteristics is vital to mitigate the O
3 problem. This study systematically investigated the long-term trends of surface O
3 in the last 10 years based on measurement from the selected 11 Air Quality Monitoring Stations (AQMS). The annual average and daily maximum 8-hours average (DMA8) O
3 presented upward trends from 2011 to 2020 at the rate of 0.66 ppb year
-1 (p<0.05) and 0.72 ppb year
-1 (p=0.06), respectively. Especially in the urban area, significant upward trends of DMA8 O
3 were found at five urban stations in the range of 0.92-1.18 ppb year
-1. Meanwhile, significant decreases in surface NO
2 were found at all 11 stations (-0.14 to -1.77 p...[
Read more ]
As a highly urbanized city in East Asia, Hong Kong has suffered from severe ozone (O
3) pollution for many years. A comprehensive understanding of the current pollution characteristics is vital to mitigate the O
3 problem. This study systematically investigated the long-term trends of surface O
3 in the last 10 years based on measurement from the selected 11 Air Quality Monitoring Stations (AQMS). The annual average and daily maximum 8-hours average (DMA8) O
3 presented upward trends from 2011 to 2020 at the rate of 0.66 ppb year
-1 (p<0.05) and 0.72 ppb year
-1 (p=0.06), respectively. Especially in the urban area, significant upward trends of DMA8 O
3 were found at five urban stations in the range of 0.92-1.18 ppb year
-1. Meanwhile, significant decreases in surface NO
2 were found at all 11 stations (-0.14 to -1.77 ppb year
-1), resulting in the decline of total oxidants (O
x, O
3+NO
2). The inverse trends of O
3 and O
x imply the rise of O
3 in urban areas was attributed to the weakened titration effect of nitrogen oxide (NO
x) emission.
Additionally, observation-based model was applied to understand the O
3-precursors relationships. Results showed that the O
3 formation was still VOC-limited in Hong Kong, and the influence of NO
x on O
3 formation decreased in recent years. In terms of abatement strategies, apart from aromatics, we highlight the importance of carbonyl compounds due to their high sensitivity to O
3 production. Because of the strict emission control measures implemented by the government of Hong Kong and adjacent areas, the locally produced O
x has been unsurprisingly alleviated, and the regional background O
x appeared to level off. However, the regional background O
3 still contributed a large fraction to O
3 concentrations and the nighttime O
3 peak formation, calling for further regional pollution control collaboration between the Hong Kong government and the adjacent Guangdong province.
Post a Comment