State Key Laboratory of Environmental and Biological Analysis, Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Kowloon, Hong Kong SAR, PR China.
State Key Joint Laboratory for Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Center for Environment and Health, Peking University, Beijing 100871, PR China.
Environ Pollut. 2019 Dec;255(Pt 1):113087. doi: 10.1016/j.envpol.2019.113087. Epub 2019 Aug 24.
Humic-like substances (HULIS) account for a considerable fraction of water-soluble organic matter (WSOM) in ambient fine particulates (PM) over the world. However, systemic studies regarding the chemical characteristics, sources and redox activity of HULIS are still limited. In this study, the mass concentration, optical properties, and reactive oxygen species (ROS)-generation potential of HULIS were investigated in PM samples collected in Hong Kong during 2011-2012, and they all showed higher levels on days under regional pollution than on days under long range transport (LRT) pollution and local emissions. Positive matrix factorization (PMF) analysis was conducted regarding the mass concentration and dithiothreitol (DTT) activity of HULIS. Four primary sources (i.e. marine vessels, industrial exhaust, biomass burning, and vehicle emissions), and two secondary sources (i.e. secondary organic aerosol formation and secondary sulfate) were identified. Most sources showed higher contributions to both the mass concentration and DTT activity of HULIS on regional days than on LRT and local days, except that marine vessels had a higher contribution on local days than the other two synoptic conditions. Secondary processes were the major contributor to HULIS (54.9%) throughout the year, followed by biomass burning (27.4%) and industrial exhaust (14.7%). As for the DTT activity of HULIS, biomass burning (62.9%) and secondary processes (25.4%) were found to be the top two contributors. Intrinsic ROS-generation potential of HULIS was also investigated by normalizing the DTT activity by HULIS mass in each source. HULIS from biomass burning were the most DTT-active, followed by marine vessels; while HULIS formed through secondary processes were the least DTT-active. For the optical properties of HULIS, multiple linear regression model was adopted to evaluate the contributions of various sources to the light absorbing ability of HULIS. Biomass burning was found to be the only source significantly associated with the light absorbing property of HULIS.
腐殖质类似物质（HULIS）在世界范围内的环境细颗粒物（PM）中占水溶性有机物质（WSOM）的相当大的一部分。然而，关于 HULIS 的化学特性、来源和氧化还原活性的系统研究仍然有限。在这项研究中，我们调查了 2011 年至 2012 年期间在香港采集的 PM 样品中 HULIS 的质量浓度、光学特性和活性氧物质（ROS）生成潜力，结果表明，在区域污染天气下，HULIS 的这些指标均高于长程传输（LRT）污染和本地排放天气。采用正定矩阵因子分解（PMF）分析了 HULIS 的质量浓度和二硫苏糖醇（DTT）活性。确定了四个主要来源（即船舶、工业废气、生物质燃烧和车辆排放）和两个次要来源（即二次有机气溶胶形成和二次硫酸盐）。除了船舶在本地天气下的贡献高于其他两种天气条件外，大多数来源在区域天气下对 HULIS 的质量浓度和 DTT 活性的贡献均高于 LRT 和本地天气。二次过程是全年 HULIS 的主要来源（54.9%），其次是生物质燃烧（27.4%）和工业废气（14.7%）。对于 HULIS 的 DTT 活性，生物质燃烧（62.9%）和二次过程（25.4%）是两个最大的贡献者。还通过在每个源中用 HULIS 质量归一化 DTT 活性来研究 HULIS 的内在 ROS 生成潜力。生物质燃烧产生的 HULIS 的 DTT 活性最高，其次是船舶；而通过二次过程形成的 HULIS 的 DTT 活性最低。对于 HULIS 的光学特性，采用多元线性回归模型来评估各种来源对 HULIS 吸光能力的贡献。发现生物质燃烧是唯一与 HULIS 吸光特性显著相关的来源。
