Unraveling urban greenhouse gas variability in Hefei: Integrating anthropogenic, biogenic, and transport controls on carbon dioxide and methane

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Abstract

Rapidly industrializing urban regions are critical hotspots for global greenhouse gas (GHG) emissions, yet their specific spatiotemporal dynamics and driving mechanisms remain complex. This study aims to elucidate the long-term variability, co-emission characteristics, and source–sink attributions of atmospheric column-averaged dry-air mole fraction of carbon dioxide (XCO₂) and methane (XCH₄) in Hefei. To achieve this, a comprehensive source–sink–transport framework was employed, integrating long-term satellite retrievals (2009–2020), high-resolution ground-based measurements, atmospheric backward trajectory modeling, and anthropogenic emission inventories. Satellite observations reveal that the XCO₂ growth rate in Hefei (2.41 ± 0.07 ppm/year) exceeded the global average, exhibiting a distinct seasonal maximum in autumn (2.7 ± 0.2 ppm/year). Meanwhile, XCH₄ showed substantial interannual variability that was highly sensitive to regional emission anomalies. Ground-based measurements captured a robust synoptic-scale diurnal co-variation in spring (R² = 0.965; ΔXCH₄/ΔXCO₂ ≈ 0.007), indicating dominant fossil fuel co-emissions. Seasonally, strong XCO₂–XCH₄ correlations in spring, autumn, and winter (R² > 0.86) confirmed the persistent influence of anthropogenic combustion. However, this correlation significantly weakened in summer (R² = 0.66) due to the decoupling effects of biogenic activities and dilution by marine air masses. Supported by backward trajectory and emission inventory analyses, the industrial, construction, and power generation sectors were identified as the primary drivers, contributing over 75% to the regional GHG emission increments. Ultimately, this study highlights the critical role of industrial and power combustion in local atmospheric GHG variability, providing quantitative insights necessary for targeted emission mitigation in super-regional developing hubs.

Keywords

Carbon dioxide

Methane

Hybrid Single Particle Lagrangian Integrated Trajectory model

Seasonal variation

Anthropogenic emission inventory

Funding

This research was supported by the High-Level Talents Project of Wanxi University (WGKQ2021007) and the Academic Award for Top Talents in University Disciplines (2022) (gxyq2022063).

Conflict of interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

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Asian Journal of Water, Environment and Pollution, Electronic ISSN: 1875-8568 Print ISSN: 0972-9860, Published by AccScience Publishing