Temporal variation of oxidative potential of water soluble components of ambient PM2.5 measured by dithiothreitol (DTT) assay

Jingpeng Wang; Xin Lin; Liping Lu; Yujie Wu; Huanxin Zhang; Qi Lv; Weiping Liu; Yanlin Zhang; Shulin Zhuang

doi:10.1016/j.scitotenv.2018.08.375

Temporal variation of oxidative potential of water soluble components of ambient PM_2.5 measured by dithiothreitol (DTT) assay

Sci Total Environ. 2019 Feb 1:649:969-978. doi: 10.1016/j.scitotenv.2018.08.375. Epub 2018 Aug 28.

Authors

Jingpeng Wang¹, Xin Lin², Liping Lu³, Yujie Wu³, Huanxin Zhang⁴, Qi Lv¹, Weiping Liu³, Yanlin Zhang², Shulin Zhuang⁵

Affiliations

¹ College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China.
² Yale-NUIST Center on Atmospheric Environment, Nanjing University of Information Science and Technology, Nanjing 210044, China.
³ College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China; Research Center for Air Pollution and Health, Zhejiang University, Hangzhou 310058, China.
⁴ College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China.
⁵ College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China; The First Affiliated Hospital College of Medicine, Zhejiang University, Hangzhou 310003, China. Electronic address: shulin@zju.edu.cn.

PMID: 30179825
DOI: 10.1016/j.scitotenv.2018.08.375

Abstract

The exposure to ambient fine particulate matter (PM_2.5) can induce oxidative stress, contributing to global burden of diseases. The evaluation of the oxidative potential (OP) of PM_2.5 is thus critical for the health risk assessment. We collected ambient PM_2.5 samples in Hangzhou city, China for four consecutive quarters in the year 2017 and investigated the oxidation property of PM_2.5 components by the dithiothreitol (DTT) assay. The annual mean of ambient PM_2.5 mass concentrations in 2017 was 63.05 μg m^-3 (median: 57.34, range: 6.67-214.33 μg m^-3) with the significant seasonal variations ranking as winter > spring > summer > autumn. Secondary inorganic aerosol (SIA) species including SO₄^2-, NO₃^- and NH₄⁺ totally account for >50% of PM_2.5 mass. The annual mean volume-normalized DTT activity (DTTv) showed a relatively high value of 0.62 nmol/min/m³ (median: 0.62, range: 0.11-1.66 nmol/min/m³) and DTTv of four seasons was roughly at the same level, indicating a high annual exposure level of ambient PM_2.5. SIA species were correlated well with the corresponding DTTv and showed significant diurnal variations with strong or moderate correlations at day and weak correlations at night, suggesting strong secondary formation in daytime with contribution to the particulate OP. The annual mean mass-normalized DTT activity (DTTm) had a relatively low value of 6.39 pmol/min/μg (median: 5.63, range: 1.99-22.70 pmol/min/μg), indicating low intrinsic oxidative toxicity. The DTTm of four seasons ranked as autumn > winter > spring > summer, indicating seasonal variations of the DTT-active components. The PM_2.5 mass concentration is more related to exposure levels than intrinsic properties of components, while OP is determined by the components rather than PM_2.5 mass concentration. Our results provide an insight into reactive oxygen species-induced health risk of PM_2.5 exposure and decision for subsequent emission control.

Keywords: Fine particulate matter; Reactive oxygen species; Secondary inorganic aerosol; Temporal variation.

MeSH terms

Air Pollutants / analysis*
China
Dithiothreitol / chemistry*
Environmental Monitoring*
Oxidation-Reduction
Particle Size
Particulate Matter / analysis*

Substances

Air Pollutants
Particulate Matter
Dithiothreitol