Tao Hongli, Tang Tian, Wang Huanbo, Huo Tingting, Yang Hao, Zhou Yan
School of Environment and Resource, Southwest University of Science and Technology, Mianyang, 621010, China.
School of Environment and Resource, Southwest University of Science and Technology, Mianyang, 621010, China.
Chemosphere. 2024 Sep;363:142845. doi: 10.1016/j.chemosphere.2024.142845. Epub 2024 Jul 14.
Nitroaromatic compounds (NACs) in ambient particles are of great concern due to their adverse effects on human health and climate. However, investigations on the characteristics and potential sources of NACs in Southwest China are still scarce. In this study, a field sampling campaign was carried out in the winter of 2022 at a suburban site in Mianyang, Southwest China. A direct injection liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed to rapidly determine 10 NACs in fine particulate matter (PM) extracts. The method was sensitive for the quantification of the NACs, with a limit of quantification (LOQ) in the range of 0.092-0.52 ng mL. Then, the developed method was applied to determine the concentrations of nitrophenols (NPs), nitrocatechols (NCs), nitrosalicylic acids (NSAs), and nitronaphthol in PM in Mianyang. The average concentration of total NACs was 78.2 ± 31.2 ng m, with daily concentrations ranging from 20.7 to 127.9 ng m. Among the measured NACs, 4-nitrocatechol was the most abundant, accounting for 57.8% of the NACs in winter. The five NPs compounds together contributed to 14% of the NACs, which was lower than in other Chinese cities due to the warm climate in winter in Southwest China. NSAs and nitronaphthol each accounted for less than 5% of the NACs. Three major sources of NACs were identified based on the principal component analysis, including vehicle emissions, biomass burning, and secondary formation. The significant correlation between individual NACs and NO supported their secondary formation sources. The good correlation between NPs and cloud amount further suggested that gas-phase oxidation was the possible NPs formation mechanism. Our findings revealed the important role of nitrocatechols in NACs in Southwest China, implying that more measures should be taken to control biomass burning and aromatic volatile organic compounds emissions to reduce the level of NACs.
环境颗粒物中的硝基芳香化合物（NACs）因其对人类健康和气候的不利影响而备受关注。然而，中国西南地区NACs的特征和潜在来源的研究仍然匮乏。在本研究中，于2022年冬季在中国西南部绵阳市的一个郊区站点开展了一次实地采样活动。开发了一种直接进样液相色谱 - 串联质谱（LC - MS/MS）方法，用于快速测定细颗粒物（PM）提取物中的10种NACs。该方法对NACs的定量具有灵敏性，定量限（LOQ）在0.092 - 0.52 ng/mL范围内。然后，将所开发的方法应用于测定绵阳市PM中硝基酚（NPs）、硝基儿茶酚（NCs）、硝基水杨酸（NSAs）和硝基萘酚的浓度。总NACs的平均浓度为78.2 ± 31.2 ng/m³，日浓度范围为20.7至127.9 ng/m³。在所测定的NACs中，4 - 硝基儿茶酚含量最高，占冬季NACs的57.8%。五种NPs化合物共同占NACs的14%，由于中国西南部冬季气候温暖，该比例低于中国其他城市。NSAs和硝基萘酚各自占NACs的比例均小于5%。基于主成分分析确定了NACs的三个主要来源，包括车辆排放、生物质燃烧和二次形成。单个NACs与NO之间的显著相关性支持了它们的二次形成来源。NPs与云量之间的良好相关性进一步表明气相氧化可能是NPs的形成机制。我们的研究结果揭示了硝基儿茶酚在中国西南部NACs中的重要作用，这意味着应采取更多措施控制生物质燃烧和芳香族挥发性有机化合物排放，以降低NACs水平。
