Atmospheric CO2 in the megacity Hangzhou, China: Urban-suburban differences, sources and impact factors

Yuanyuan Chen; Yanran Lu; Bing Qi; Qianli Ma; Kunpeng Zang; Yi Lin; Shuo Liu; Fengmei Pan; Shan Li; Peng Guo; Lihan Chen; Wengang Lan; Shuangxi Fang

doi:10.1016/j.scitotenv.2024.171635

Atmospheric CO₂ in the megacity Hangzhou, China: Urban-suburban differences, sources and impact factors

Sci Total Environ. 2024 May 20:926:171635. doi: 10.1016/j.scitotenv.2024.171635. Epub 2024 Mar 13.

Authors

Yuanyuan Chen¹, Yanran Lu¹, Bing Qi², Qianli Ma³, Kunpeng Zang¹, Yi Lin¹, Shuo Liu¹, Fengmei Pan¹, Shan Li¹, Peng Guo¹, Lihan Chen¹, Wengang Lan¹, Shuangxi Fang⁴

Affiliations

¹ Zhejiang Carbon Neutral Innovation Institute & Zhejiang International Cooperation Base for Science and Technology on Carbon Emission Reduction and Monitoring, Zhejiang University of Technology, Hangzhou 310014, China; College of Environment, Zhejiang University of Technology, Hangzhou 310014, China.
² Hangzhou Meteorological Bureau, Hangzhou 310051, China.
³ Lin'an Regional Background Station, China Meteorological Administration, Zhejiang 314016, China.
⁴ Zhejiang Carbon Neutral Innovation Institute & Zhejiang International Cooperation Base for Science and Technology on Carbon Emission Reduction and Monitoring, Zhejiang University of Technology, Hangzhou 310014, China; College of Environment, Zhejiang University of Technology, Hangzhou 310014, China; Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters(CIC-FEMD), Nanjing University of Information Science & Technology, Nanjing 210044, China. Electronic address: fangsx@zjut.edu.cn.

PMID: 38490430
DOI: 10.1016/j.scitotenv.2024.171635

Abstract

Limited observation sites and insufficient monitoring of atmospheric CO₂ in urban areas restrict our comprehension of urban-suburban disparities. This research endeavored to shed light on the urban-suburban differences of atmospheric CO₂ in levels, diurnal and seasonal variations as well as the potential sources and impact factors in the megacity of Hangzhou, China, where the economically most developed region in China is. The observations derived from the existing Hangzhou Atmospheric Composition Monitoring Center Station (HZ) and Lin'an Regional Atmospheric Background Station (LAN) and the newly established high-altitude Daming Mountain Atmospheric Observation Station (DMS), were utilized. From November 2020 to October 2021, the annual averages of HZ, LAN and DMS were 446.52 ± 17.01 ppm, 441.56 ± 15.42 ppm, and 422.02 ± 10.67 ppm. The difference in atmospheric CO₂ mole fraction between HZ and LAN was lower compared to the urban-suburban differences observed in other major cities in China, such as Shanghai, Nanjing, and Beijing. Simultaneous CO₂ enhancements were observed at HZ and LAN, when using DMS observations as background references. The seasonal variations of CO₂ at LAN and DMS exhibited a high negative correlation with the normalized difference vegetation index (NDVI) values, indicating the strong regulatory of vegetation canopy. The variations in boundary layer height had a larger influence on the low-altitude HZ and LAN stations than DMS. Compared to HZ and LAN, the atmospheric CO₂ at DMS was influenced by emissions and transmissions over a wider range. The potential source area of DMS in autumn covered most areas of the urban agglomeration in eastern China. DMS measurements could provide a reliable representation of the background level of CO₂ emissions in the Yangtze River Delta and a broader region. Conventional understanding of regional CO₂ level in the Yangtze River Delta through LAN measurements may overestimate background concentration by approximately 10.92 ppm.

Keywords: Background level; Boundary layer height; Carbon dioxide; Urban-suburban difference; Variation.