Development of a preparation system for the radiocarbon analysis of organic carbon in carbonaceous aerosols in China

Zhang, Y.L.; Liu, D.; Shen, Chengde; Ding, Ping; Zhang, Guoren

doi:10.1016/j.nimb.2010.06.032

Cited by 24 publications

(44 citation statements)

References 25 publications

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“…Carbon fractions must be converted into pure CO 2 individually prior to their 14 C measurements, for which preparation approaches have been described in our previous studies [ Liu et al ., , ; Zhang et al ., ]. In this study, the isolated carbon amounts were typically in the range of 30–100 µg, depending on the samples.…”

Section: Methodsmentioning

confidence: 99%

Radiocarbon‐derived source apportionment of fine carbonaceous aerosols before, during, and after the 2014 Asia‐Pacific Economic Cooperation (APEC) summit in Beijing, China

Liu

et al. 2016

JGR Atmospheres

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The Asia‐Pacific Economic Cooperation (APEC) summit took place in Beijing, China, 5–11 November 2014, during which numerous measures were performed to control the air pollution, and consequently, the sky of Beijing was so clean that the public called it “APEC blue.” The concentrations before, during, and after the APEC summit are 14.4 ± 6.81 µg C/m3, 6.66 ± 2.99 µg C/m3, and 32.3 ± 10.6 µg C/m3, respectively, for organic carbon (OC), and 2.27 ± 1.17 µg C/m3, 0.76 ± 0.52 µg C/m3, and 4.99 ± 1.74 µg C/m3, respectively, for elemental carbon (EC). We quantify the contributions of fossil and nonfossil sources to the OC and EC using radiocarbon. Results show that the contribution of nonfossil sources is 56 ± 1% (before APEC), 61 ± 1% (during APEC), and 48 ± 1% (after APEC), respectively, for OC, and 36 ± 4% (before APEC), 46 ± 1% (during APEC), and 33 ± 4% (after APEC), respectively, for EC. Comparing to the period before APEC, 70% and 60% of fossil EC and OC and 60% and 50% of nonfossil EC and OC are reduced, respectively, implying that the control on the nonfossil sources has considerable contribution to the good air quality in Beijing. Both EC and OC mass loadings during the APEC summit would have increased by 60% if the biomass‐burning activities were not taken into account for control. In such a case, the atmospheric visibility would decrease 20% at least and the blue sky thereby would likely not have been visible during the summit.

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Section: Methodsmentioning

confidence: 99%

Radiocarbon‐derived source apportionment of fine carbonaceous aerosols before, during, and after the 2014 Asia‐Pacific Economic Cooperation (APEC) summit in Beijing, China

Liu

et al. 2016

JGR Atmospheres

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“…30 Although charring can be minimized by performing the water extraction step prior to the thermal treatment, 10,30,31 it is not adequate to separate all of the OC. 16,18 A longer separation duration for the elimination of the OC, for example, 12 and 24 h, was suggested at 375°C in air. 20,32 In this study, the determination of the 14 C in the EC was performed by the evaporation of the OC at 375°C in a muffle furnace in the presence of air 16,32,33 using a shorter separation time of 4 h to achieve the complete removal of the OC from the EC fraction (Supporting Information (SI)).…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

The Use of Levoglucosan and Radiocarbon for Source Apportionment of PM_2.5Carbonaceous Aerosols at a Background Site in East China

Liu¹,

Li²,

Zhang³

et al. 2013

Environ. Sci. Technol.

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Samples of fine particulate matter (PM 2.5 ) were collected during July 2009 to March 2010 at a regional background site in East China. The mass concentrations of organic carbon (OC) and elemental carbon (EC) were characterized by the highest levels in winter (December to February) and the lowest abundances in summer (June to August). Conversely, the concentrations of levoglucosan were higher in summer than in winter. The observations were associated to the anthropogenic air pollutions (predominantly fossil-fuel combustions) transport from the center and north China with the northwest winds in winter and large contribution of the open biomass burning activities in South China and East China in summer, which was evident by air-mass trajectories and MODIS satellite fire counts. To assign fossil and nonfossil contributions of carbonaceous matters, the radiocarbon contents in water-insoluble OC (WINSOC) and EC in 4 combined samples representing four seasons were analyzed using the isolation system established in China. The results indicated that biomass burning and biogenic sources (59%) were the major contribution to the WINSOC, whereas fossil fuel (78%) was the dominant contributor to the refractory EC at this site. The source variation obtained by radiocarbon was consistent with other indicators, such as the OC/EC ratios and the levoglucosan concentration. Biomass burning and biogenic emissions were found to predominate in the summer and autumn, whereas fossil fuel emissions predominate in winter and spring.

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“…This two-step combustion method was further optimised for OC and EC quantification by Lavanchy et al (1999) and then adapted to a Two-step Heating system for the EC/OC Determination Of Radiocarbon in the Environment (THEODORE, Szidat et al, 2004a), which was then adopted by many other laboratories (e.g. Zhang et al, 2010;Calzolai et al, 2011). A technique with chemo-thermal oxidation at 375 • C in air (CTO-375) is also commonly applied to determine EC or BC (Gustafsson et al, 2001) and isolate EC from aerosols for subsequent off-line radiocarbon analysis (Zencak et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

On the isolation of OC and EC and the optimal strategy of radiocarbon-based source apportionment of carbonaceous aerosols

Zhang¹,

Perron²,

Ciobanu³

et al. 2012

Preprint

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Radiocarbon (14C) measurements of elemental carbon (EC) and organic carbon (OC) separately (as opposed to only total carbon, TC) allow an unambiguous quantification of their non-fossil and fossil sources and represent an improvement in carbonaceous aerosol source apportionment. Isolation of OC and EC for accurate 14C determination requires complete removal of interfering fractions with maximum recovery. To evaluate the extent of positive and negative artefacts during OC and EC separation, we performed sample preparation with a commercial Thermo-Optical OC/EC Analyser (TOA) by monitoring the optical properties of the sample during the thermal treatments. Extensive attention has been devoted to the set-up of TOA conditions, in particular, heating program and choice of carrier gas. Based on different types of carbonaceous aerosols samples, an optimised TOA protocol (Swiss_4S) with four steps is developed to minimise the charring of OC, the premature combustion of EC and thus artefacts of 14C-based source apportionment of EC. For the isolation of EC for 14C analysis, the water-extraction treatment on the filter prior to any thermal treatment is an essential prerequisite for subsequent radiocarbon; otherwise the non-fossil contribution may be overestimated due to the positive bias from charring. The Swiss_4S protocol involves the following consecutive four steps (S1, S2, S3 and S4): (1) S1 in pure oxygen (O2) at 375 °C for separation of OC for untreated filters, and water-insoluble organic carbon (WINSOC) for water-extracted filters; (2) S2 in O2 at 475 °C, followed by (3) S3 in helium (He) at 650 °C, aiming at complete OC removal before EC isolation and leading to better consistency with thermal-optical protocols like EUSAAR_2, compared to pure oxygen methods; and (4) S4 in O2 at 760 °C for recovery of the remaining EC. WINSOC was found to have a significantly higher fossil contribution than the water-soluble OC (WSOC). Moreover, the experimental results demonstrate the lower refractivity of wood-burning EC compared to fossil EC and the difficulty of clearly isolating EC without premature evolution. Hence, simplified techniques of EC isolation for 14C analysis are prone to a substantial bias and generally tend towards an underestimation of the non-fossil sources. Consequently, the optimal strategy for 14C-based source apportionment of carbonaceous aerosols should follow an approach to subdivide TC into different carbonaceous aerosol fractions for individual 14C analyses, as these fractions differ in their origins. To obtain the comprehensive picture of the sources of carbonaceous aerosols, the Swiss_4S protocol is not only implemented to measure OC and EC fractions, but also WINSOC as wel...

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Development of a preparation system for the radiocarbon analysis of organic carbon in carbonaceous aerosols in China

Cited by 24 publications

References 25 publications

Radiocarbon‐derived source apportionment of fine carbonaceous aerosols before, during, and after the 2014 Asia‐Pacific Economic Cooperation (APEC) summit in Beijing, China

Radiocarbon‐derived source apportionment of fine carbonaceous aerosols before, during, and after the 2014 Asia‐Pacific Economic Cooperation (APEC) summit in Beijing, China

The Use of Levoglucosan and Radiocarbon for Source Apportionment of PM_2.5Carbonaceous Aerosols at a Background Site in East China

On the isolation of OC and EC and the optimal strategy of radiocarbon-based source apportionment of carbonaceous aerosols

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Development of a preparation system for the radiocarbon analysis of organic carbon in carbonaceous aerosols in China

Cited by 24 publications

References 25 publications

Radiocarbon‐derived source apportionment of fine carbonaceous aerosols before, during, and after the 2014 Asia‐Pacific Economic Cooperation (APEC) summit in Beijing, China

Radiocarbon‐derived source apportionment of fine carbonaceous aerosols before, during, and after the 2014 Asia‐Pacific Economic Cooperation (APEC) summit in Beijing, China

The Use of Levoglucosan and Radiocarbon for Source Apportionment of PM2.5Carbonaceous Aerosols at a Background Site in East China

On the isolation of OC and EC and the optimal strategy of radiocarbon-based source apportionment of carbonaceous aerosols

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The Use of Levoglucosan and Radiocarbon for Source Apportionment of PM_2.5Carbonaceous Aerosols at a Background Site in East China