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<p>Ammonia (NH<sub>3</sub>) is a key precursor of fine particulate matter (PM<sub>2.5</sub>) in the air; however, its emission sources at different heights remain poorly understood in the Pearl River Delta (PRD) region of China. In this study, we simultaneously collected PM<sub>2.5</sub> samples at three atmospheric heights (ground, 118 m, and 488 m) based on the atmospheric observatories of Canton Tower, the tallest structure in the PRD region. Our results showed that the average NH<sub>4</sub><sup>+</sup> concentrations were 2.7 ± 1.4, 3.0 ± 1.8, and 2.6 ± 1.7 µg/m<sup>3</sup> at the ground site, 118 m, and 488 m during the sampling campaign, with no significant difference (<i>p</i> &gt; 0.05) among the three heights. However, the stable nitrogen isotope composition values in NH<sub>4</sub><sup>+</sup> (δ<sup>15</sup>N-NH<sub>4</sub><sup>+</sup>) displayed a significant correlation with height (<i>p</i> &lt; 0.05). We further calculated the initial δ<sup>15</sup>N-NH<sub>3</sub> values and performed source apportionments using the Bayesian Isotope Mixture Model. The results indicated that the mean contributions of agriculture, waste, vehicle, biomass burning, NH<sub>3</sub> slip, and coal combustion were 9.9% ± 4.4%, 8.3% ± 5.5%, 29% ± 8.0%, 16% ± 2.2%, 25% ± 6.0%, and 12% ± 3.4%, respectively, at the ground site during the sampling campaign. By contrast, the contributions of sources at 488 m remained relatively stable due to the limited influence of local activities. Overall, our study highlights the dominant role of combustion sources in NH<sub>3</sub> emissions in the PRD region, with their contribution being highly dependent on atmospheric height.</p>

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Combustion-related activities dominate atmospheric ammonia in the Pearl River Delta region, China

  • 期刊论文

  • 发表日期：

    2025年4月15日

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  • Mengzhi He,
  • Junwen Liu,
  • Chenglei Pei,
  • Fan Jiang,
  • Zixi Chen,
  • Xueqin Zheng,
  • Xiaoxiao Yang,
  • Guanghui Li,
  • Zheng Zong,
  • Fang Cao,
  • Yanlin Zhang,
  • Chongguo Tian

摘要

Ammonia (NH3) is a key precursor of fine particulate matter (PM2.5) in the air; however, its emission sources at different heights remain poorly understood in the Pearl River Delta (PRD) region of China. In this study, we simultaneously collected PM2.5 samples at three atmospheric heights (ground, 118 m, and 488 m) based on the atmospheric observatories of Canton Tower, the tallest structure in the PRD region. Our results showed that the average NH4+ concentrations were 2.7 ± 1.4, 3.0 ± 1.8, and 2.6 ± 1.7 µg/m3 at the ground site, 118 m, and 488 m during the sampling campaign, with no significant difference (p > 0.05) among the three heights. However, the stable nitrogen isotope composition values in NH4+ (δ15N-NH4+) displayed a significant correlation with height (p < 0.05). We further calculated the initial δ15N-NH3 values and performed source apportionments using the Bayesian Isotope Mixture Model. The results indicated that the mean contributions of agriculture, waste, vehicle, biomass burning, NH3 slip, and coal combustion were 9.9% ± 4.4%, 8.3% ± 5.5%, 29% ± 8.0%, 16% ± 2.2%, 25% ± 6.0%, and 12% ± 3.4%, respectively, at the ground site during the sampling campaign. By contrast, the contributions of sources at 488 m remained relatively stable due to the limited influence of local activities. Overall, our study highlights the dominant role of combustion sources in NH3 emissions in the PRD region, with their contribution being highly dependent on atmospheric height.