Optical properties, chemical functional group, and oxidative activity of different polarity levels of water-soluble organic matter in PM2.5 from biomass and coal combustion in rural areas in Northwest China
Optical properties, chemical functional group, and oxidative activity of different polarity levels of water-soluble organic matter in PM2.5 from biomass and coal combustion in rural areas in Northwest China
复制标题
西北农村地区生物质和燃煤PM2.5中水溶性有机物不同极性水平的光学性质、化学官能团及氧化活性
DOI：
10.1016/j.atmosenv.2022.119179
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发表时间：
2022
影响因子：
5
通讯作者：
Zhenxing Shen
中科院分区：
文献类型：
--
作者：
Shasha Huang;Yu Luo;Xin Wang;Tian Zhang;Yali Lei;Yaling Zeng;Jian Sun;Huizheng Che;Hongmei Xu;Junji Cao;Zhenxing Shen
生物质和燃煤是PM2.5中水溶性有机物的主要来源研究了西北地区生物质和煤燃烧产生的中性类腐殖酸（HULIS-n）、酸性类腐殖酸（HULIS-a）和高极性类腐殖酸（HP-WSOM）的碳含量、光吸收能力、分子结构和氧化活性。HULIS-n、HULIS-a和HP-WSOM生物质燃烧的碳排放因子分别为5.52 ± 4.29、3.82 ± 2.83和3.24 ± 2.85 g/kg，煤燃烧的碳排放因子分别为1.77 ± 0.65、4.41 ± 1.24和3.94 ± 1.78 g/kg。HULIS-n在365 nm处的光吸收系数（B abs-365）和质量吸收效率（MAE 365）均最高，表明HULIS-n含有更多的发色团。傅里叶变换红外光谱分析结果表明，HULIS-n和HP-WSOM中主要含有芳香物质和多糖。煤燃烧过程中活性氧（ROS）的变化规律为HULIS-n > HP-WSOM > HULIS-a。在生物质燃烧的WSOM方面，火炕中玉米秸秆和小麦秸秆的HULIS-n活性氧含量最高，而壁挂炉和木块火中辣椒棒和芝麻棒的HP-WSOM活性氧含量最高。生物质燃烧HS产生的HULIS-a具有较高的ROS活性，而HB和SS燃烧生物质产生的HULIS-n的氧化活性差异不大。HULIS-n在生物质燃烧和煤燃烧中都具有较高的活性氧含量和较强的光吸收，这可能与其富含R-ONO 2有机硝酸盐的分子结构有关。研究结果还表明，在煤燃烧过程中，HULIS-n的碳含量仅占HULIS + HP-WSOM的17.5%，而HULIS-n对总光吸收和ROS的贡献高达58.3%和64.8%。总体而言，这项研究揭示了WSOM的复杂排放特性，这将改善其在区域尺度上的环境和气候影响的评估。·来自生物质燃烧的HULIS + HP-WSOM的碳含量几乎是煤燃烧的两倍。·来自煤燃烧的HULIS-n显示出最高的ROS但最低的碳含量。·HULIS-n的高活性氧和光吸收应归因于含氮有机物。
Biomass and coal combustion are major sources of water-soluble organic matter (WSOM) in PM 2.5 . This study investigated the carbon content, light absorption capacity, molecular structures, and oxidative activity of three types of WSOM (neutral humic-like substances (HULIS-n), acidic HULIS (HULIS-a), and high-polarity WSOM (HP-WSOM)) produced from biomass and coal combustion in Northwest China. The carbon emission factors of HULIS-n, HULIS-a, and HP-WSOM were 5.52 ± 4.29, 3.82 ± 2.83, and 3.24 ± 2.85 g/kg from biomass burning, and 1.77 ± 0.65, 4.41 ± 1.24, and 3.94 ± 1.78 g/kg from coal combustion, respectively. HULIS-n had the highest light absorption coefficient at 365 nm (b abs-365 ) and the mass absorption efficiency at 365 nm (MAE 365 ) both for biomass and coal burning, suggesting that HULIS-n contains more chromophores than the others. The Fourier transform infrared spectra results revealed that aromatic substances and polysaccharides were predominated in HULIS-n and HP-WSOM. Reactive oxygen species (ROS) in coal combustion followed a decreasing order of HULIS-n > HP-WSOM > HULIS-a. In terms of WSOM from biomass combustion, the highest ROS was in HULIS-n for corn straw and wheat straw in fire kangs but the highest ROS was in HP-WSOM for pepper rod and sesame rod in hanging stoves as well as wood block fire. HULIS-a produced by HS of biomass burning had higher ROS activity, and oxidative activity of HULIS-n produced by burning biomass by HB and SS did not differ greatly. High ROS and strong light absorption of HULIS-n in both biomass burning and coal burning may attribute to its molecular structures such as abundance of R–ONO 2 organic nitrate. Our results also highlighted that the carbon content of HULIS-n occupied only 17.5% to HULIS + HP-WSOM in coal combustion, whereas HULIS-n contributed up to 58.3% and 64.8% of the total light absorption and ROS. Overall, this study revealed the complex emission properties of WSOM, which would improve the assessment of their environmental and climate impacts at a regional scale. • The carbon content of HULIS + HP-WSOM from biomass burning was nearly double than coal combustion. • HULIS-n from coal combustion showed the highest ROS but lowest carbon content. • High ROS and light absorption of HULIS-n should attribute to nitrogenous organic substances.