Modal Characteristics of Elemental and Organic Carbon in an Urban Location in Guangzhou, China

Abstract

Carbonaceous matter is a major constituent in urban aerosols, especially in those collected in China. The size distributions of elemental carbon (EC) and organic carbon (OC) in the range of 0.01-18 µm were measured in an urban location in Guangzhou, China in July 2006. The EC size distribution in the accumulationmode size was characterized by three significant modes with mass median aerodynamic diameters (MMAD) of ∼0.15 µm, ∼0.40 µm, and ∼0.90 µm, with the second one being the most prominent and accounting for approximately half of the total EC mass. The coexistence of the first two accumulation modes in Guangzhou's urban atmosphere could be explained to be a result of emissions from vehicles operating at different loadings. The dominance of the EC accumulation mode at ∼0.40 µm has not often been reported in studies conducted in developed countries, but this observation is consistent with EC size distributions measured in a roadway tunnel in this region. This information is important when modeling the role of EC in modulating the radiative balance and investigating the health effects of EC. The third accumulation mode was postulated to be a result of in-cloud processing after emission. OC had the same size modes as EC but different mass distributions among the modes. The carbonaceous materials in the nucleation mode were dominated by OC. Among particles in the accumulation size range, the OC/EC ratio was higher in the third accumulation mode (MMAD: 0.90 µm) than in the first two accumulation modes, suggesting that in-cloud processing was an important pathway for accumulating OC mass during atmospheric processing of EC particles.

Characteristics of Organic Carbon and Elemental Carbon in the Ambient Air of Coking Plant

“…Inorganic carbon is a small proportion of the TC in ambient air particulate matter (Na et al, 2004;Cao et al, 2007;Yu and Yu, 2009;Niu et al, 2013); therefore Eq. (1) was used to calculate the mass concentration of EC:…”

“…Carbonaceous aerosol, which accounts for a substantial fraction of ambient aerosols (Yu and Yu, 2009), profoundly affects air quality, visibility, climate, and human health (Mark, 2001;Ye et al, 2003;Satsangi et al, 2012;Zhang et al, 2012;Cao et al, 2013;Zhang et al, 2013). It is a complex mixture, primarily containing organic carbon (OC) and elemental carbon (EC) (Cao et al, 2003;Satsangi et al, 2012).…”

Size distributions of elemental carbon and its contribution to light extinction in urban and rural locations in the pearl river delta region, China

“…Instead, positive matrix factorization (PMF2, version 4.2) has been used to apportion the evolved C peaks (OC 1 -OC 4 and EC 1 -EC 5 ) in the thermograms to OC and EC. The method details are presented in our previous paper (Yu and Yu, 2009). Compared with apparent EC (AEC, the sum of EC 1 -EC 5 , i.e., the amount of carbon that is released from the filter substrate during the second stage of analysis in O 2 /He atmosphere), the PMF-resolved EC accounts for 77% of AEC and the PMFresolved OC is 112% of apparent OC (AOC, the sum of OC 1 -OC 4 ) in the GZ urban samples.…”

“…Gnauk et al (2008) measured EC, OC, and a few selected organic compound classes in size-segregated aerosols in Xinken, a rural/coastal background site 60 km to the southeast of Guangzhou. Our group reported EC size distributions in Shenzhen and Guangzhou, two metropolitan cities in the PRD region (Huang and Yu, 2008;Yu and Yu, 2009). In this study, we report the measurements of EC size distributions at five urban locations in Guangzhou throughout a one-year period from December 2006 to December 2007 and one suburban and one rural location in the PRD region in selected summer and winter months.…”

Size Distributions of Polycyclic Aromatic Hydrocarbons at Two Receptor Sites in the Pearl River Delta Region, China: Implications of a Dominant Droplet Mode

“…EC and OM concentrations (C i EC and C i OM ) were measured in this study. EC surface area density can be estimated assuming that the condensation-mode EC particles are spherical particles of diameter 0.26 µm and the droplet-mode EC originates from spherical EC particles of diameter 0.42 µm, on the basis of observations in the PRD urban areas, followed by in-cloud processing and cloud evaporation (Yu and Yu 2009;Huang et al 2006b). N s is taken to be 4 × 10 −10 mol cm −2 (Pankow 1987); the difference between desorption enthalpy and vaporization enthalpy Q l -Q v ≈ 3 kcal mol −1 is extracted from Pankow (1987) and experimentally confirmed by Aubin and Abbatt (2006) and Guilloteau et al (2010).…”