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Field characterization of the PM2.5 Aerosol Chemical Speciation Monitor: insights into the composition, sources, and processes of fine particles in eastern China.
- Source :
- Atmospheric Chemistry & Physics; 2017, Vol. 17 Issue 23, p14501-14517, 17p, 11 Graphs
- Publication Year :
- 2017
-
Abstract
- A PM<subscript>2.5</subscript>-capable aerosol chemical speciation monitor (Q-ACSM) was deployed in urban Nanjing, China, for the first time to measure in situ non-refractory fine particle (NR-PM<subscript>2.5</subscript>) composition from 20 October to 19 November 2015, along with parallel measurements of submicron aerosol (PM<subscript>1</subscript>) species by a standard Q-ACSM. Our results show that the NR-PM<subscript>2.5</subscript> species (organics, sulfate, nitrate, and ammonium) measured by the PM<subscript>2.5</subscript>-Q-ACSM are highly correlated (r2 > 0.9) with those measured by a Sunset Lab OC / EC analyzer and a Monitor for AeRosols and GAses (MARGA). The comparisons between the two Q-ACSMs illustrated similar temporal variations in all NR species between PM<subscript>1</subscript> and PM<subscript>2.5</subscript>, yet substantial mass fractions of aerosol species were observed in the size range of <subscript>1-2.5</subscript> µm. On average, NR-PM<subscript>1-2.5</subscript> contributed 53% of the total NR-PM<subscript>2.5</subscript>, with sulfate and secondary organic aerosols (SOAs) being the two largest contributors (26 and 27%, respectively). Positive matrix factorization of organic aerosol showed similar temporal variations in both primary and secondary OAs between PM<subscript>1</subscript> and PM<subscript>2.5</subscript>, although the mass spectra were slightly different due to more thermal decomposition on the capture vaporizer of the PM<subscript>2.5</subscript>-Q-ACSM. We observed an enhancement of SOA under high relative humidity conditions, which is associated with simultaneous increases in aerosol pH, gas-phase species (NO<subscript>2</subscript>, SO<subscript>2</subscript>, and NH<subscript>3</subscript>) concentrations and aerosol water content driven by secondary inorganic aerosols. These results likely indicate an enhanced reactive uptake of SOA precursors upon aqueous particles. Therefore, reducing anthropogenic NO<subscript>x</subscript>, SO<subscript>2</subscript>, and NH<subscript>3</subscript> emissions might not only reduce secondary inorganic aerosols but also the SOA burden during haze episodes in China. [ABSTRACT FROM AUTHOR]
- Subjects :
- CHEMICAL speciation
ATMOSPHERIC aerosols
PARTICLES
ATMOSPHERIC aerosol measurement
Subjects
Details
- Language :
- English
- ISSN :
- 16807316
- Volume :
- 17
- Issue :
- 23
- Database :
- Complementary Index
- Journal :
- Atmospheric Chemistry & Physics
- Publication Type :
- Academic Journal
- Accession number :
- 126865287
- Full Text :
- https://doi.org/10.5194/acp-17-14501-2017