Source Apportionment of Ammonium in Atmospheric PM2.5 in the Pearl River Delta Based on Nitrogen Isotope

doi:10.16258/j.cnki.1674-5906.2022.09.014

Ecology and Environment ›› 2022, Vol. 31 ›› Issue (9): 1840-1848.DOI: 10.16258/j.cnki.1674-5906.2022.09.014

• Research Articles • Previous Articles Next Articles

Source Apportionment of Ammonium in Atmospheric PM_2.5 in the Pearl River Delta Based on Nitrogen Isotope

JIANG Ming¹(), ZHANG Ziyang², LI Tingting², LIN Boji², ZHANG Zhengen², LIAO Tong¹, YUAN Luan¹, PAN Suhong³, LI Jun²^,^*(), ZHANG Gan²

1. National Key Laboratory for Regional Air Quality Monitoring of Environmental Protection/Guangdong Ecological Environment Monitoring Center, Guangzhou 510308, P. R. China
2. State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, P. R. China
3. Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, P. R. China

Received:2022-08-18 Online:2022-09-18 Published:2022-11-07
Contact: LI Jun

基于氮同位素的珠三角典型地区大气PM_2.5中NH₄⁺来源解析

江明¹(), 张子洋², 李婷婷², 林勃机², 张正恩², 廖彤¹, 袁鸾¹, 潘苏红³, 李军²^,^*(), 张干²

1.国家环境保护区域空气质量监测重点实验室/广东省生态环境监测中心,广东广州 510308
2.有机地球化学国家重点实验室,中国科学院广州地球化学研究所,广东广州 510640
3.广东省科学院生态环境与土壤研究所,广东广州 5106501;

通讯作者: 李军
作者简介:江明（1977年生）,男,高级工程师,硕士,主要研究方向环境空气质量监测与研究。E-mail: jm787@139.com
基金资助:
广东省重点领域研发计划项目(2020B1111360003);国家自然科学基金项目(41977177)

Abstract

Abstract:

Ammonium (NH₄⁺) could promote particle formation and hygroscopic growth and is an important component of fine particles (PM_2.5), but its source contribution is still unclear. There are some challenges in accurately analyzing the source of atmospheric NH₄⁺. In recent years, the source apportionment method based on nitrogen isotope has been widely applied to the source apportionment of atmospheric NH₄⁺. In this study, Heshan atmospheric super-station in the Pearl River Delta was selected as the research site to carry out a one-year collection of atmospheric PM_2.5 samples. A total of 53 atmospheric PM_2.5 samples were selected. Based on the analysis of water-soluble ions, organic carbon, elemental carbon and inorganic elements, the δ¹⁵N value of ammonium was tested. The results showed that the annual average concentration of ammonium at Heshan station was (3.39±2.21) μg∙m^-3, ranging from 0.07 to 10.9 μg∙m^-3. The results of the molar ratio of ammonium to anions showed that Heshan region was rich in ammonium, and the results of random forest model showed that NH₄⁺ had an important effect on the formation of PM_2.5 in Heshan region. The δ¹⁵N-NH₄⁺ value in atmospheric particulate matter ranged from -14.55‰ to 18.82‰, with the largest variation in winter (-13.27‰-18.82‰) and the smallest variation in summer (-2.32‰-10.94‰). The source apportionment results analyzed by Bayesian model showed that the average annual contributions of agricultural sources (livestock and fertilizer) and non-agricultural sources (biomass combustion, coal combustion, vehicle emissions and waste) to atmospheric NH₃ were 36.26% and 63.74% respectively. During the heavily polluted days in winter (January 6, January 12 and January 18, 2021), while the NH₄⁺ concentration reached the peak of the whole year, the proportion of non-agricultural source emissions also reached the highest level of the whole year, up to 90.80%. Among them, the emission of vehicles was 2-4 times that of the clean days, indicating that fossil fuel combustion was an important cause of pollution events in winter. The contribution of NH₃ emission from non-agricultural sources based on isotope source analysis method was about 7 times that of the emission inventory method. The emission inventory method may seriously underestimate the emission contribution of important non-agricultural sources such as vehicles. In order to further improve the air quality in the Pearl River Delta, it is necessary to pay attention to the emission of NH₃ from non-agricultural sources.

Key words: Pearl River Delta, Heshan atmospheric super-station, PM_2.5, ammonium, nitrogen isotope, source apportionment

摘要：

铵根离子（NH₄⁺）可促进颗粒形成和吸湿长大,是雾霾颗粒（PM_2.5）的重要组分,但其源贡献尚不清楚。准确解析大气NH₄⁺来源存在一定挑战。最近,基于NH₄⁺氮同位素（δ¹⁵N）的源解析方法被广泛应用到大气NH₄⁺来源解析。以珠三角鹤山大气超级站为研究地点,开展为期1年的大气PM_2.5样品采集,选取了53个大气PM_2.5样品,在分析了水溶性离子、有机碳、元素碳和无机元素的基础上,测试了NH₄⁺的δ¹⁵N值。结果表明,鹤山站大气NH₄⁺年均质量浓度为 (3.39±2.21) μg∙m^-3,范围为0.07-10.9 μg∙m^-3。NH₄⁺与阴离子物质的量比结果显示鹤山地区为富铵状态,且随机森林模型结果表明,NH₄⁺对于鹤山地区PM_2.5的生成具有重要影响。大气颗粒物δ¹⁵N-NH₄⁺范围为-14.55‰-18.82‰,其中冬季δ¹⁵N-NH₄⁺变化最大（-13.27‰-18.82‰）,夏季δ¹⁵N-NH₄⁺变化最小（-2.32‰-10.94‰）。贝叶斯源解析结果显示,农业源（畜牧和施肥）和非农业源（生物质燃烧、煤燃烧、机动车排放和废弃物）对大气NH₃的年均贡献分别为36.26%和63.74%。在冬季重污染天时（2021年1月6日、1月12日和1月18日）,NH₄⁺浓度达全年峰值的同时,非农业源排放占比也达全年最高水平,最高达90.80%,其中机动车排放是非污染天的2-4倍,显示化石燃料燃烧是导致冬季污染事件的重要原因。基于同位素源解析方法所得非农业源NH₃排放贡献约为源清单方法所得结果的7倍,源清单法可能严重低估了机动车等重要非农业源的排放贡献。为了进一步改善珠三角地区空气质量,需要重视非农业源NH₃的排放。

关键词: 珠三角, 鹤山大气超级站, PM_2.5, 铵根离子（NH₄⁺）, 氮同位素, 源解析

CLC Number:

Q948
X16

JIANG Ming, ZHANG Ziyang, LI Tingting, LIN Boji, ZHANG Zhengen, LIAO Tong, YUAN Luan, PAN Suhong, LI Jun, ZHANG Gan. Source Apportionment of Ammonium in Atmospheric PM_2.5 in the Pearl River Delta Based on Nitrogen Isotope[J]. Ecology and Environment, 2022, 31(9): 1840-1848.

江明, 张子洋, 李婷婷, 林勃机, 张正恩, 廖彤, 袁鸾, 潘苏红, 李军, 张干. 基于氮同位素的珠三角典型地区大气PM_2.5中NH₄⁺来源解析[J]. 生态环境学报, 2022, 31(9): 1840-1848.

Figures/Tables 6

Figure 1 Temperature, humidity, wind speed and direction, NH4+ concentration and its proportion to PM2.5, δ15N-NH4+and δ15N-NH3 values during sampling periods

Table 1 Correlation between NH4+ and NO3-, SO42-

采样时段 Period	NH₄⁺与NO₃^-的相关性 Correlation between NH₄⁺and NO₃^-	NH₄⁺与NO₃^-的相关性SO₄^2- Correlation between NH₄⁺ and SO₄^2-
秋天 Autumn	r²=0.64; P<0.001	r²=0.39; P=0.031
冬天 Winter	r²=0.85; P<0.001	r²=0.52; P<0.001
春天 Spring	r²=0.76; P<0.001	r²=0.55; P<0.001
夏天 Summer	r²=0.34; P=0.076	r²=0.36; P=0.065
年均 Annual	r²=0.77; P<0.001	r²=0.44; P<0.001

Figure 2 Effects of various factors on the generation of PM2.5 (from Random Forest Analysis results)

Figure 3 Annual and quarterly contribution of each emission source

Figure 4 Relationship between NH4+ concentration and δ15N-NH3 in different seasons

Figure 5 Comparison of NH3 from non-agricultural sources based on isotope and source inventory methods in typical regions of China

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