Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Hong Kong SAR, China.
State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China; CAS Center for Excellence in Quaternary Science and Global Change, Xi'an 710061, China.
Sci Total Environ. 2022 Mar 15;812:151451. doi: 10.1016/j.scitotenv.2021.151451. Epub 2021 Nov 13.
Organic nitrogen constitutes a significant fraction of the nitrogen budget in particulate matter (PM). However, the composition and sources of nitrogen-containing organic compounds (NOCs) in PM remain unclear currently in North China Plain (NCP), China. Rare local or regional studies on NOCs were conducted. In this study, ambient fine particles (PM) were collected in Xianghe, a regional background site in NCP, from 26 October to 26 December 2017. The insights from this study include NOC molecule identification, concentration level, and NOC sources and origins. Specifically, we have identified and quantified >90 NOC species, with urea being the most abundant, accounting for 39.7 ± 4.7% of the total NOC followed by free amino acids (FAAs; 21.9 ± 1.5%), cyclic NOCs (15.3 ± 4.5%), amines (14.8 ± 1.5%), alkyl amides (5.8 ± 0.5%), isocyanates (1.7 ± 0.2%), and nitriles (1.1 ± 0.2%). The time series of FAAs was well correlated (r = 0.51-0.68, p < 0.01) with the organic marker of levoglucosan and was moderately correlated with O (r = 0.29-0.41, p < 0.01), suggesting biomass burning and secondary formation were important FAAs sources. We also show that amines can be oxidized and/or reacted by aqueous-phase processing to form secondary aerosols, which are further enhanced by the involvement of iron in the catalytic process. Using the receptor model of positive matrix factorization (PMF), six factors were identified including coal combustion, crustal sources, biomass burning, industry-related sources, traffic emissions, and secondary aerosols. Source apportionment of NOC shows biomass burning was the dominant factor, accounting for 31.8% of the total NOCs. This study provides a unique dataset of NOCs at this regional background site in the NCP, with the insights of NOC chemical composition and sources gained in this study being important for future NOC modeling as well as NOC health effects studies.
有机氮是颗粒物（PM）氮预算的重要组成部分。然而，目前在中国华北平原（NCP），含氮有机化合物（NOCs）的组成和来源仍不清楚。很少有关于 NOCs 的本地或区域研究。在这项研究中，我们于 2017 年 10 月 26 日至 12 月 26 日在 NCP 的一个区域背景站点香河采集了环境细颗粒物（PM）。本研究的结果包括 NOC 分子鉴定、浓度水平以及 NOC 来源和起源。具体来说，我们已经鉴定和量化了超过 90 种 NOC 物种，其中尿素含量最丰富，占总 NOC 的 39.7±4.7%，其次是游离氨基酸（FAAs；21.9±1.5%）、环状 NOC（15.3±4.5%）、胺（14.8±1.5%）、烷基酰胺（5.8±0.5%）、异氰酸酯（1.7±0.2%）和腈（1.1±0.2%）。FAAs 的时间序列与有机标记物左旋葡聚糖很好地相关（r=0.51-0.68，p<0.01），与 O 中度相关（r=0.29-0.41，p<0.01），表明生物质燃烧和二次形成是 FAAs 的重要来源。我们还表明，胺可以通过水相处理氧化和/或反应形成二次气溶胶，并且铁在催化过程中的参与进一步增强了它们的形成。使用正矩阵因子化（PMF）受体模型，我们确定了六个因子，包括煤炭燃烧、地壳源、生物质燃烧、工业相关源、交通排放和二次气溶胶。NOC 的源分配表明，生物质燃烧是主要因素，占总 NOC 的 31.8%。本研究提供了 NCP 区域背景站点 NOC 的独特数据集，本研究中获得的 NOC 化学组成和来源的见解对于未来的 NOC 建模以及 NOC 健康效应研究非常重要。
