| 南京近郊农田区域大气颗粒物水溶性离子污染特征 |
| 摘要点击 1013 全文点击 223 投稿时间：2024-01-11 修订日期：2024-04-14 |
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| 中文关键词 农田 大气颗粒物 水溶性离子 粒径分布 污染特征 |
| 英文关键词 farmland atmospheric particulates water-soluble ions size distribution pollution characteristics |
| 作者 | 单位 | E-mail | | 潘超 | 国家能源集团科学技术研究院有限公司, 清洁高效燃煤发电与污染控制国家重点实验室, 南京 210023 | pcxyz@139.com | | 张海鸥 | 南京信息工程大学环境科学与工程学院, 江苏省大气环境监测与污染控制高技术研究重点实验室, 江苏省大气环境与装备技术协同创新中心, 南京 210044 | | | 刘婉萍 | 南京信息工程大学环境科学与工程学院, 江苏省大气环境监测与污染控制高技术研究重点实验室, 江苏省大气环境与装备技术协同创新中心, 南京 210044 | | | 张鸿燕 | 南京信息工程大学环境科学与工程学院, 江苏省大气环境监测与污染控制高技术研究重点实验室, 江苏省大气环境与装备技术协同创新中心, 南京 210044 | | | 樊建凌 | 南京信息工程大学环境科学与工程学院, 江苏省大气环境监测与污染控制高技术研究重点实验室, 江苏省大气环境与装备技术协同创新中心, 南京 210044 | jlfan@nuist.edu.cn |
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| 中文摘要 |
| 水溶性离子是大气颗粒物中重要组成部分,但当前对农业区域大气颗粒物中水溶性离子的研究与关注较少.于2020年12月至2021年11月对南京近郊农业区定点连续采样,分析了不同粒径大气颗粒物（>9.0、 5.8~9.0、 4.7~5.8、 3.3~4.7、 2.1~3.3、 1.1~2.1、0.65~1.1、 0.43~0.65和<0.43 μm）中8种水溶性离子（Na+、 NH4+、K+、 Mg2+、 Ca2+、 NO3-、 SO42-和Cl-）污染特征.结果表明,采样期内采样点大气总悬浮颗粒物（TSP）、< 9.0 μm和< 2.1 μm的颗粒物浓度年均值分别为54.73、49.04和27.35 μg·m-3,均达到了国家二级标准,其中< 2.1 μm的颗粒物浓度占TSP的50.0%,说明细颗粒物是该区域大气颗粒物的主要成分.不同粒径颗粒物中水溶性离子浓度均表现为：秋季>春/夏季>冬季；在各季节及各粒径颗粒中,SO42-是水溶性离子的主要贡献者,占比在30.6%~66.5%之间,SO42-/NO3-的值远大于1,表明研究区以固定源污染贡献为主.不同粒径颗粒物中SOR（SO2气-粒转化速率）仅在冬季个别时间出现小于0.1的情况,表明研究区SO42-主要来源于SO2的二次氧化.除4.7~5.8 μm 粒径外,其余粒径颗粒物中SOR与温度均呈显著正相关（P < 0.05）,表明温度的升高显著促进了各粒径颗粒物中SO42-的光化学形成过程；然而,SOR与相对湿度仅在< 2.1 μm的细颗粒物中呈显著正相关（P < 0.05）,表明液相反应是细颗粒物中SO42-形成的重要途径.采用主成分分析对颗粒物中水溶性离子来源进行解析,结果发现南京市近郊农田细颗粒物中的水溶性离子主要来自于SO2等的二次转化；而粗颗粒物中水溶性离子主要来源于农田翻耕时的土壤扬尘.研究结果对了解农业区域大气颗粒物中水溶性离子污染特征具有重要意义,为了解南京近郊农业区大气颗粒物污染来源及形成机制提供了参考依据. |
| 英文摘要 |
| Water-soluble ions are an important component of atmospheric particles. However, there has been limited research on water-soluble inorganic ions in atmospheric particulates in agricultural areas until now. In this study, the characteristics of eight water-soluble inorganic ions （Na+, NH4+, K+, Mg2+, Ca2+, NO3-, SO42-, and Cl-） in different sizes of atmospheric particulates （>9.0, 5.8-9.0, 4.7-5.8, 3.3-4.7, 2.1-3.3, 1.1-2.1, 0.65-1.1, 0.43-0.65, and <0.43 μm） were analyzed by sampling farmland in the suburb of Nanjing from December 2020 to November 2021. The results showed that the annual mass concentrations of total suspended particulate matter （TSP）, < 9.0 μm and < 2.1 μm particulates were 54.73, 49.04, and 27.35 μg·m-3, respectively, all of which reached the national secondary standards. The mass concentration of < 2.1 μm particulates accounted for 50.0% of TSP, indicating that fine particles were the main components of atmospheric particulates in this area. The concentration of water-soluble inorganic ions in different sizes of particulates was highest in autumn, followed by those in spring/summer and winter. SO42- was the primary contributor among all seasons and particle sizes, accounting for 30.6%-66.5%. The ratio of SO42-/NO3- was much higher than 1, indicating that the contribution of fixed-source pollution played a dominant role in the study area. Moreover, SOR （SO2 gas-particle conversion rate） in different particle sizes was less than 0.1 only at individual times in winter, indicating that SO42- was mainly derived from the secondary oxidation of SO2 in the study area. Significant positive correlations （P < 0.05） between SOR and temperature were observed except for 4.7-5.8 μm particulates, indicating that the increase in temperature significantly promoted the photochemical formation process of SO42- in particles with different sizes. However, the relationship between SOR and relative humidity was significant only in fine particulates smaller than 2.1 μm （P < 0.05）, indicating that the liquid phase reaction was an important pathway for the formation of SO42- in fine particles. Principal component analysis was used to analyze the sources of water-soluble inorganic ions in particulates. Moreover, it showed that water-soluble inorganic ions in fine particulates mainly came from the secondary transformation of SO2, while those in the coarse particles mainly came from the soil dust during farmland tillage. The results of this study are of great significance for understanding the characteristics of water-soluble inorganic ion pollution in atmospheric particulate matter in agricultural areas. They provide a reference for understanding the source and formation mechanisms of atmospheric particulate matter pollution in agricultural areas near Nanjing. |
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