Abstract

A year-long study was performed to comprehensively investigate the mass concentration, water-soluble ions, organic and elemental carbons, and elemental components of atmospheric fine particles from March 2006 to February 2007 in Qingdao. The results showed that PM2.5 concentration was over twice the National Ambient Air Quality Standards of 35 μg/m3 (GB3095-2012), with the highest value in winter (110 μg/m3) and the lowest in summer (42.8 μg/m3). Non-sea salt-SO42− (nss-SO42−), NO3−, and NH4+ were the dominant water-soluble ions in PM2.5, and showed the highest concentrations in autumn, winter and autumn, respectively, and all had the lowest concentrations in summer. Organic carbon (OC) and elemental carbon (EC) had the lowest levels in summer and the highest values in winter and autumn, respectively. The lower acetic/formic acid (A/F) ratio in summer suggested a predominant secondary formation of water-soluble organic acids. Cl-depletion mainly occurred in summer, along with the largest sea salt proportion in particles in a year when winds came from the southeastern sea. The enrichment factors (EFs) of elements followed an increasing order: Si, Al, Ti, Mg, Ca, Fe, Na, Sr, K, Mn, Ba, V, Cr, Ni, Co, Sc, Cu, As, Cl, Zn, Pb, S, Br, Cd, and Se. The higher EFs from 10.1 to 10,487 for Sr, K, Mn, Ba, V, Cr, Ni, Co, Sc, Cu, Cl, Zn, Pb, S, Br, Cd, and Se suggested the significant influence of anthropogenic sources in the area. Mass closure showed that (NH4)2SO4, organic matter, and NH4NO3 were the main components, and contributed 31.0%, 25.2%, and 14.0% of PM2.5 mass in Qingdao, respectively. Source apportionment results showed that secondary sulfate, nitrate, and coal combustion were the main sources. Based on this study and previous publications, the PM2.5 characteristics—including seasonality in mass and chemical species concentrations and Cl-depletion in summer—were obtained across coastal cities in China.

Highlights

  • Atmospheric fine particles are a complicated mixture with an important influence on atmospheric processes, climate change, and human health [1,2,3]

  • When enrichment factors (EFs) is close to 1, the element i is mainly derived from the crustal source, when EF is greater than 10, it indicates that the element i primarily originates from anthropogenic source, and when EF is between 1 and 10, the anthropogenic source is small while natural source is still the main factor for the element i

  • A brief introduction of the locations, sampling dates, and analyses for these studies are listed in Table S1, and the concentrations of SO4 2−, NO3 −, NH4 +, Organic carbon (OC), and elemental carbon (EC) in these cities are compiled in Tables S2 and S3

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Summary

Introduction

Atmospheric fine particles are a complicated mixture with an important influence on atmospheric processes, climate change, and human health [1,2,3]. A holistic of fine particles pollution those in inland and are studied relatively scarcely [8,14].understanding. Particles pollution characteristics coastal cities in China is still unknown. Due to its important significant beeninmade in the characteristics of the cityof[15], the possible origin of the water-soluble particle characteristics the including city [15], seasonal includingvariation seasonaland variation and the possible origin of the ions [5], sea salt contribution fine particlesto [5], concentration, variation, the size distribution water-soluble ions [5], sea salttocontribution fine particles [5],seasonal concentration, seasonal variation, the of airborne microbes in bio-aerosols [16],in and so forth. Green, and blue solid circles stand for Qingdao, the two inland of (Table S1) in China. Ji’nan in the North China Plain, and the coastal cities in China, respectively

Sampling
Water-Soluble Ions
Inorganic Elements
Enrichment Factor
Chemical Mass Closure
Results and Discussions
Water-Soluble
Seasonal
Carbonaceous Species
Elemental Components
Mass Closure
Source
Coastal
Cl-Depletion
Conclusions
Background
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