The Influence of Dust on Quantitative Measurements of Black Carbon in Ice and Snow when Using a Thermal Optical Method

Wang, Mo; Xu, Bin; Zhao, Huabiao; Cao, Junji; Joswiak, Daniel R.; Wu, Guangjian; Lin, Shubiao

doi:10.1080/02786826.2011.605815

Cited by 63 publications

(73 citation statements)

References 25 publications

(39 reference statements)

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“…However, this shortcoming did not substantially influence the accuracy of the correction during subsequent carbon evolution. We note that premature evolution of EC, leading to an increasing laser signal in the inert environment due to the existence of refractory metal oxides, was observed in the studies of Wang et al (2012) and Bladt et al (2012). The increases in the corrected laser signal during the He stage in this study may be partially due to the same cause, as Riyadh samples contained abundant metal oxides.…”

Section: Discussionmentioning

confidence: 62%

“…However, unusual EC and OC splits for a large number of samples were observed during the study period: (a) split points jumped to the end of the analysis because the laser response did not rebound to its initial value before the CH 4 calibration phase; or (b) split points were located in the pre-oxygen position. These split-point deviations were ascribed to refractory residue on the filters: the laser correction factor supplied in the standard manufacturer software may not be applicable to the dusty environment of Riyadh (Polidori et al, 2006;Jung et al, 2011;Wang et al, 2012). Therefore, observed relationships between laser response and temperature in the CH 4 + O 2 injection calibration phase were used to develop a corrected split point.…”

Section: Ec and Oc Re-split Methodsmentioning

confidence: 99%

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Sources of PM<sub>2.5</sub> carbonaceous aerosol in Riyadh, Saudi Arabia

et al. 2018

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Abstract. Knowledge of the sources of carbonaceous aerosol affecting air quality in Riyadh, Saudi Arabia, is limited but needed for the development of pollution control strategies. We conducted sampling of PM 2.5 from April to September 2012 at various sites in the city and used a thermo-optical semi-continuous method to quantify the organic carbon (OC) and elemental carbon (EC) concentrations. The average OC and EC concentrations were 4.7 ± 4.4 and 2.1 ± 2.5 µg m −3 , respectively, during this period. Both OC and EC concentrations had strong diurnal variations, with peaks at 06:00-08:00 LT and 20:00-22:00 LT, attributed to the combined effect of increased vehicle emissions during rush hour and the shallow boundary layer in the early morning and at night. This finding suggested a significant influence of local vehicular emissions on OC and EC. The OC / EC ratio in primary emissions was estimated to be 1.01, close to documented values for diesel emissions. Estimated primary organic carbon (POC) and secondary organic carbon (SOC) concentrations were comparable, with average concentrations of 2.0 ± 2.4 and 2.8 ± 3.4 µg m −3 , respectively.We also collected 24 h samples of PM 10 onto quartz microfiber filters and analyzed these for an array of metals by inductively coupled plasma atomic emission spectroscopy (ICP-AES). Total OC was correlated with Ca (R 2 of 0.63), suggesting that OC precursors and Ca may have similar sources, and the possibility that they underwent similar atmospheric processing. In addition to a ubiquitous dust source, Ca is emitted during desalting processes in the numerous refineries in the region and from cement kilns, suggesting these sources may also contribute to observed OC concentrations in Riyadh. Concentration weighted trajectory (CWT) analysis showed that high OC and EC concentrations were associated with air masses arriving from the Persian Gulf and the region around Baghdad, locations with high densities of oil fields and refineries as well as a large Saudi Arabian cement plant. We further applied positive matrix factorization to the aligned dataset of EC, OC, and metal concentrations (Al, Ca, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, and V). Three factors were derived and were proposed to be associated with oil combustion, industrial emissions (Pb based), and a combined source from oil fields, cement production, and local vehicular emissions. The dominant OC and EC source was the combined source, contributing 3.9 µg m −3 (80 %) to observed OC and 1.9 µg m −3 (92 %) to observed EC.

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Section: Discussionmentioning

confidence: 62%

Section: Ec and Oc Re-split Methodsmentioning

confidence: 99%

Sources of PM<sub>2.5</sub> carbonaceous aerosol in Riyadh, Saudi Arabia

et al. 2018

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“…BC and OC on the filters were measured using a method similar to the IMPROVE protocol (Cao et al, 2003;Chow et al, 2004). Because the filters had more dust load than those collected from ice core samples or aerosol samples (Wang et al, 2012), we modified the method that in 100% helium atmosphere, only a temperature plateau (550 C) was arranged to reduce the time that BC was exposed in catalyzing atmosphere. BC results were reported regardless of the optical signal.…”

Section: Samples and Methodsmentioning

confidence: 99%

“…Immediately after melt, the liquid was sonicated and filtered through quartz fiber filters (Supplemental Materials) (Schwarz et al, 2012;Wang et al, 2012). BC and OC on the filters were measured using a method similar to the IMPROVE protocol (Cao et al, 2003;Chow et al, 2004).…”

Section: Samples and Methodsmentioning

confidence: 99%

Climate effect of black carbon aerosol in a Tibetan Plateau glacier

Song

Cao

et al. 2015

Atmospheric Environment

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h i g h l i g h t sWe sampled surface snow and snow pits in the snowmelt season in a Tibetan glacier. We depicted the variability of BC, OC, and dust concentrations. Scavenging efficiency and enrichment for BC and OC were derived. We evaluated BC radiative forcing in snow using SNICAR. a r t i c l e i n f o a b s t r a c tIn the Tibetan Plateau, the black carbon (BC) concentration in surface snow and snow pits has received much attention, whereas the seasonal behavior of aerosol-in-snow concentration, vertical profile, meltscavenging, and enrichment have received relatively little attention. Here we investigate these processes and their impacts on radiative forcing on the Muji glacier in the westernmost Tibetan Plateau during the 2012 snowmelt season. Increasing impurity concentrations were mostly due to post-deposition effects rather than new deposition. On 5 July, BC concentrations in the surface snow were higher than those of fresh snow, implying enrichment via sublimation and/or melting of previous snow. Fresh snow contained 25 ng g À1 BC on 27 July; afterward, BC gradually increased, reaching 730.6 ng g À1 in September. BC, organic carbon (OC), and dust concentrations co-varied but differed in magnitude. Melt-scavenging efficiencies were estimated at 0.19 ± 0.05 and 0.04 ± 0.01 for OC and BC, respectively, and the BC in surface snow increased by 20e25 times depending on melt intensity. BC-in-snow radiative forcing (RF) was approximately 2.2 W m À2 for fresh snow and 18.1e20.4 W m À2 for aged snow, and was sometimes reduced by the presence of dust.

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“…At dusty sites, such as the Himalayas, dust may interfere with the thermal-optical method (e.g. Wang et al, 2012) resulting in additional problems with comparing records, but dust should not be a problem when comparing records from the Arctic. …”

Section: Uncertaintiesmentioning

confidence: 99%

Increase in elemental carbon values between 1970 and 2004 observed in a 300-year ice core from Holtedahlfonna (Svalbard)

et al. 2014

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Abstract. Black carbon (BC) is a light-absorbing particle that warms the atmosphere–Earth system. The climate effects of BC are amplified in the Arctic, where its deposition on light surfaces decreases the albedo and causes earlier melt of snow and ice. Despite its suggested significant role in Arctic climate warming, there is little information on BC concentrations and deposition in the past. Here we present results on BC (here operationally defined as elemental carbon (EC)) concentrations and deposition on a Svalbard glacier between 1700 and 2004. The inner part of a 125 m deep ice core from Holtedahlfonna glacier (79°8' N, 13°16' E, 1150 m a.s.l.) was melted, filtered through a quartz fibre filter and analysed for EC using a thermal–optical method. The EC values started to increase after 1850 and peaked around 1910, similar to ice core records from Greenland. Strikingly, the EC values again increase rapidly between 1970 and 2004 after a temporary low point around 1970, reaching unprecedented values in the 1990s. This rise is not seen in Greenland ice cores, and it seems to contradict atmospheric BC measurements indicating generally decreasing atmospheric BC concentrations since 1989 in the Arctic. For example, changes in scavenging efficiencies, post-depositional processes and differences in the vertical distribution of BC in the atmosphere are discussed for the differences between the Svalbard and Greenland ice core records, as well as the ice core and atmospheric measurements in Svalbard. In addition, the divergent BC trends between Greenland and Svalbard ice cores may be caused by differences in the analytical methods used, including the operational definitions of quantified particles, and detection efficiencies of different-sized BC particles. Regardless of the cause of the increasing EC values between 1970 and 2004, the results have significant implications for the past radiative energy balance at the coring site.

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The Influence of Dust on Quantitative Measurements of Black Carbon in Ice and Snow when Using a Thermal Optical Method

Cited by 63 publications

References 25 publications

Sources of PM<sub>2.5</sub> carbonaceous aerosol in Riyadh, Saudi Arabia

Sources of PM<sub>2.5</sub> carbonaceous aerosol in Riyadh, Saudi Arabia

Climate effect of black carbon aerosol in a Tibetan Plateau glacier

Increase in elemental carbon values between 1970 and 2004 observed in a 300-year ice core from Holtedahlfonna (Svalbard)

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The Influence of Dust on Quantitative Measurements of Black Carbon in Ice and Snow when Using a Thermal Optical Method

Cited by 63 publications

References 25 publications

Sources of PM&lt;sub&gt;2.5&lt;/sub&gt; carbonaceous aerosol in Riyadh, Saudi Arabia

Sources of PM&lt;sub&gt;2.5&lt;/sub&gt; carbonaceous aerosol in Riyadh, Saudi Arabia

Climate effect of black carbon aerosol in a Tibetan Plateau glacier

Increase in elemental carbon values between 1970 and 2004 observed in a 300-year ice core from Holtedahlfonna (Svalbard)

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Sources of PM<sub>2.5</sub> carbonaceous aerosol in Riyadh, Saudi Arabia

Sources of PM<sub>2.5</sub> carbonaceous aerosol in Riyadh, Saudi Arabia