loading page

Oxidative Potential and Chemical Characteristics of Ambient PM2.5 in Guangzhou, China
  • +4
  • Peng Cheng,
  • Manman Zhang,
  • Yongjie Li,
  • Mingjin Tang,
  • Wenda Yang,
  • Cheng Wu,
  • Jiayin Sun
Peng Cheng
Jinan University

Corresponding Author:chengp@jnu.edu.cn

Author Profile
Manman Zhang
Henan University of Chinese Medicine
Author Profile
Yongjie Li
University of Macau
Author Profile
Mingjin Tang
Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, State Key Laboratory of Organic Geochemistry
Author Profile
Wenda Yang
Jinan University
Author Profile
Cheng Wu
Jinan University
Author Profile
Jiayin Sun
Jinan university
Author Profile

Abstract

The dithiothreitol (DTT) assay is widely used to characterize the Oxidation Potential (OP) of atmospheric particulate matter (PM), which can cause adverse effects on human health. However, it’s under debate which chemical species determines the consumption rate of DTT. During January and April 2018, we measured the improved DTT assay of daily PM2.5 samples collected in Guangzhou, China with complimentary measurements of water-soluble ions, organic/elemental carbon (OC/EC) and metal elements. The average sampled air volume normalized consumption rate of DTT (DTTv) was 4.67 ±1.06 and 4.45 ± 1.02 nmol min-1 m-3, in January and April, respectively while the average PM2.5 mass normalized consumption rate of DTT (DTTm) was 13.47 ± 3.86 and 14.66 ± 4.49 pmol min-1 μg-1. Good correlations were found between DTTv and concentration of PM2.5, OC, and EC while no correlation was found between DTTm and concentrations of water-soluble ions, OC, EC or metal element, which is consistent with most early observations. We also evaluated the contribution of soluble metals to DTT assay by addition of EDTA, a strong metal chelator. We found that nearly 90% of DTTv and DTTm were reduced by EDTA, suggesting a dominant role of soluble metals in determining the response of DTT to ambient PM2.5. Based on responses of DTT to soluble metals in literature, we found that Cu(II) and Mn(II) are the major contributors to OP of PM2.5 in Guangzhou. The correlation coefficient between DTTm and OC shows a clear increase after addition of EDTA, implying that the response of DTT to quinones is not strongly suppressed by EDTA.