Size-resolved effective density of submicron particles during summertime in the rural atmosphere of Beijing, China

• Particle density is an important physical property of atmospheric particles. The information on high time-resolution size-resolved particle density is essential for understanding the atmospheric physical and chemical aging processes of aerosols particles. In the present study, a centrifugal particle mass analyzer (CPMA) combined with a differential mobility analyzer (DMA) was deployed to determine the size-resolved effective density of 50 to 350 nm particles at a rural site of Beijing during summer 2016. The measured particle effective densities decreased with increasing particle sizes and ranged from 1.43 to 1.55 g/cm(3), on average. The effective particle density distributions were dominated by a mode peaked at around 1.5 g/cm(3) for 50 to 350 nm particles. Extra modes with peaks at 1.0, 0.8, and 0.6 g/cm(3) for 150, 240, and 350 nm particles, which might be freshly emitted soot particles, were observed during intensive primary emissions episodes. The particle effective densities showed a diurnal variation pattern, with higher values during daytime. A case study showed that the effective density of Aitken mode particles during the new particle formation (NPF) event decreased considerably, indicating the significant contribution of organics to new particle growth. (C) 2018 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.

Ämnesord

NATURVETENSKAP  -- Kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences (hsv//eng)

NATURVETENSKAP  -- Geovetenskap och miljövetenskap (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences (hsv//eng)

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Miljövetenskap (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Environmental Sciences (hsv//eng)

NATURVETENSKAP  -- Kemi -- Fysikalisk kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Physical Chemistry (hsv//eng)

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Meteorologi och atmosfärforskning (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Meteorology and Atmospheric Sciences (hsv//eng)

NATURVETENSKAP  -- Biologi -- Ekologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Ecology (hsv//eng)

NATURVETENSKAP  -- Kemi -- Analytisk kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Analytical Chemistry (hsv//eng)

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Klimatforskning (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Climate Research (hsv//eng)

Nyckelord

Effective density

Atmospheric aerosol

Centrifugal particle mass analyzer

Rural site

New particle

secondary organic aerosol

mass analyzer

sulfuric-acid

diurnal-variation

haze formation

urban

mobility

growth

soot

hygroscopicity

Environmental Sciences & Ecology

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