Wei Xu, Liang Guiyun, Mao Jingying, Yang Junchao, Mu Yijun, Nong Chuan, Zhang Dabiao, Lu Jiahui, Huang Xishou, Wu Ying, Mo Zhaoyu
Scientific Research Academy of Guangxi Environmental Protection, Nanning, Guangxi, China; Gansu Pingliang Ecological Environment Monitoring Center, China.
Scientific Research Academy of Guangxi Environmental Protection, Nanning, Guangxi, China.
Environ Pollut. 2025 Sep 15;381:126633. doi: 10.1016/j.envpol.2025.126633. Epub 2025 Jun 6.
Guangxi is one of the main sugarcane-producing areas in China, with its cultivated sugarcane area accounting for more than 60 % of the national total. Open burning of sugarcane stalks is thus a significant contributor to fine particulate matter (PM) pollution in the region during winter. In this study, a PM pollution event is analyzed in Nanning, the capital of Guangxi, from February 24-28, 2022. Results showed a significant increase in PM concentrations and its components during the pollution period. Among them, K, Cl Na, and EC, which are heavily influenced by open straw burning, increased by 4.50, 4.25, 3.50, and 3.02 times, respectively, compared to the non-polluted period. PM concentrations rose sharply at night (19:00 on February 26), and the subsequent accumulation of pollutants increased atmospheric oxidizing capacity the following day. This facilitated the conversion of SO and NOx, leading to a sudden increase in secondary inorganic aerosols (SIA) and causing PM concentrations to peak again during the daytime. The concentration characteristics of SO, NOx, and NH indicated that nitric acid was the limiting species in the SIA generation process. This revealed that oxidation and neutralization reactions involving NOx and NH were critical mechanisms for the increase in PM concentrations during the open burning of sugarcane straw in winter in Guangxi. This study reveals the importance of strengthening the control of anthropogenic emissions of NOx and NH during wintertime straw burning in Southern China.
广西是中国主要的甘蔗产区之一，其甘蔗种植面积占全国总面积的60%以上。因此，冬季甘蔗秸秆露天焚烧是该地区细颗粒物（PM）污染的一个重要来源。本研究分析了2022年2月24日至28日广西首府南宁发生的一次PM污染事件。结果显示，污染期间PM浓度及其组分显著增加。其中，受秸秆露天焚烧影响较大的K、Cl、Na和EC，与未污染时期相比，分别增加了4.50倍、4.25倍、3.50倍和3.02倍。PM浓度在夜间（2月26日19:00）急剧上升，随后污染物的累积使次日大气氧化能力增强。这促进了SO和NOx的转化，导致二次无机气溶胶（SIA）突然增加，并使PM浓度在白天再次达到峰值。SO、NOx和NH的浓度特征表明，硝酸是SIA生成过程中的限制物种。这表明，涉及NOx和NH的氧化和中和反应是广西冬季甘蔗秸秆露天焚烧期间PM浓度增加的关键机制。本研究揭示了在中国南方冬季秸秆焚烧期间加强对NOx和NH人为排放控制的重要性。
