Preprints
https://doi.org/10.5194/egusphere-2024-2503
https://doi.org/10.5194/egusphere-2024-2503
21 Nov 2024
 | 21 Nov 2024
Status: this preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).

Sources and trends of Black Carbon Aerosol in a Megacity of Nanjing, East China After the China Clean Action Plan and Three-Year Action Plan

Abudurexiati Abulimiti, Yanlin Zhang, Mingyuan Yu, Yihang Hong, Yu-Chi Lin, Chaman Gul, and Fang Cao

Abstract. Black carbon (BC) is an essential component of particulate matter (PM) with a significant impact on climate change. Few studies have investigated the long-term changes in BC and the sources, particularly considering primary emissions of BC, which is crucial for developing effective mitigation strategies. Here, based on three-year observations (2019–2021), random forest (RF) algorithms were employed to reconstruct BC concentrations in Nanjing from 2014 to 2021. Source apportionment was conducted on the reconstructed data to investigate long-term trends of BC and its sources. The results showed that the three-year average BC concentration was 2.5±1.6 μg m-3, peaking in winter, with approximately 80 % attributed to liquid fuel combustion. Notably, the reconstructed time series revealed a significant decrease (p < 0.05) in BC levels over the eight-year period, primarily due to reduced emissions from liquid fuels. The comparison between two control polices periods (P1:2014–2017 and P2:2018–2021) indicate that BC concentrations decline more steeply during S2 since significant (p < 0.05) reduction in biomass burning. The seasonal analysis showed significant reductions (p < 0.05) in BC, BCliquid (black carbon from liquid fuel combustion) and BCsolid (black carbon from solid fuel combustion) during winter, with BCliquid accounting for 77 % of the reduction. Overall, emission reduction was the dominant factor in reducing BC levels, contributing between 62 % and 86 %, as revealed by Kolmogorov-Zurbenko (KZ) filter. However, during P2, meteorological conditions played a more significant role, especially in reducing BC and BCliquid, with an increase in their impact on BCsolid compared to P1. Our results demonstrated that target control measures for liquid fuel combustion are necessary, as liquid fuel combustion is a major driver of decreasing BC, especially in summer, while the influence of meteorological factors on BC variations cannot be overlooked.

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Abudurexiati Abulimiti, Yanlin Zhang, Mingyuan Yu, Yihang Hong, Yu-Chi Lin, Chaman Gul, and Fang Cao

Status: open (until 06 Jan 2025)

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  • RC1: 'Comment on egusphere-2024-2503', Anonymous Referee #1, 05 Dec 2024 reply
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Abudurexiati Abulimiti, Yanlin Zhang, Mingyuan Yu, Yihang Hong, Yu-Chi Lin, Chaman Gul, and Fang Cao
Abudurexiati Abulimiti, Yanlin Zhang, Mingyuan Yu, Yihang Hong, Yu-Chi Lin, Chaman Gul, and Fang Cao

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Short summary
To improve air quality, the Chinese government implemented strict clean air actions. We explored how black carbon (BC) responded to these actions and found that the reduction in liquid fuel use was the main factor driving the decrease in BC levels. Additionally, meteorological factors also played a significant role in the long-term trends of BC. These factors should be considered in future emission reduction policies to further enhance air quality improvements.