Carbonaceous aerosols on the south edge of the Tibetan Plateau: concentrations, seasonality and sources

Cong, Zhiyuan; Kang, Shichang; Kawamura, Kimitaka; Liu, B.; Wan, Xin; Wang, Z.; Gao, Shaopeng; Fu, Pingqing

doi:10.5194/acp-15-1573-2015

Cited by 239 publications

(192 citation statements)

References 57 publications

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“…The average ratios for Regions I, II, and III were 1.82, 1.31, and 1.14, respectively (Table 2), indicating a decreasing impact of biomasssourced aerosol deposition in snow over the TP. The slightly higher OC / BC in Region I may be due to its proximity to South Asian combustion sources dominated by biomass burning (Cong et al, 2015a, b;Li et al, 2016). For example, in the LHG region, lower LAP concentrations in fresh clean snow were observed at LHG3 and LHG6 (Fig.…”

Section: Distributions Of Lapsmentioning

confidence: 95%

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Black carbon and mineral dust in snow cover on the Tibetan Plateau

et al. 2018

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Abstract. Snow cover plays a key role for sustaining ecology and society in mountainous regions. Light-absorbing particulates (including black carbon, organic carbon, and mineral dust) deposited on snow can reduce surface albedo and contribute to the near-worldwide melting of snow and ice. This study focused on understanding the role of black carbon and other water-insoluble light-absorbing particulates in the snow cover of the Tibetan Plateau (TP). The results found that the black carbon, organic carbon, and dust concentrations in snow cover generally ranged from 202 to 17 468 ng g −1 , 491 to 13 880 ng g −1 , and 22 to 846 µg g −1 , respectively, with higher concentrations in the central to northern areas of the TP. Back trajectory analysis suggested that the northern TP was influenced mainly by air masses from Central Asia with some Eurasian influence, and air masses in the central and Himalayan region originated mainly from Central and South Asia. The relative biomassburning-sourced black carbon contributions decreased from ∼ 50 % in the southern TP to ∼ 30 % in the northern TP. The relative contribution of black carbon and dust to snow albedo reduction reached approximately 37 and 15 %, respectively. The effect of black carbon and dust reduced the snow cover duration by 3.1 ± 0.1 to 4.4 ± 0.2 days. Meanwhile, the black carbon and dust had important implications for snowmelt water loss over the TP. The findings indicate that the impacts of black carbon and mineral dust need to be properly accounted for in future regional climate projections, particularly in the high-altitude cryosphere.

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Section: Distributions Of Lapsmentioning

confidence: 95%

“…Ratios of OC to BC (OC / BC) were used to examine the possible impact of biomass burning in previous studies (Watson et al, 2001;Bond et al, 2013;Cong et al, 2015a, b). Usually, the aerosols emitted from biomass burning have higher OC / BC ratios than that from fossil fuel combustion.…”

Section: Distributions Of Lapsmentioning

confidence: 99%

Black carbon and mineral dust in snow cover on the Tibetan Plateau

et al. 2018

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“…The so-called "Atmospheric Brown Cloud (ABC)", a 3 kmthick brownish layer of pollutants, has been detected extending from the Indian Ocean to the Himalayas (Tripathi et al, 2005;Ramanathan et al, 2007). The aerosols that gather in the foothills can be lifted to high altitudes Qiu, 2013) and can even travel across the high Himalayas and reach the Tibetan Plateau (TP) (Bonasoni, 2008;Xia et al, 2011;Chen et al, 2015a;Cong et al, 2015;Lüthi et al, 2015), thus affecting the atmospheric quality and causing environmental risks in the high and remote regions.…”

Section: Introductionmentioning

confidence: 99%

Characteristics of Particulate-Phase Polycyclic Aromatic Hydrocarbons (PAHs) in the Atmosphere over the Central Himalayas

Chen

Kang

et al. 2017

Aerosol Air Qual. Res.

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PAH concentrations were measured in total suspended particle (TSP) samples collected from six sites along two southnorth transects across the central Himalayas from April 2013 to March 2014. The annual average TSP and PAH (especially 5-and 6-ring compounds) concentrations were found to decrease noticeably northwards along both transects. At rural and urban sites, the TSP and PAH concentrations showed clear seasonal variations, with the lower concentrations around the mid-monsoon season and the higher values in the winter season. Meanwhile, at the remote sites (e.g., Nyalam and Zhongba), these pollutants generally remained constant throughout the year but with relatively higher levels during the pre-monsoon season. Both IndP/(IndP + BghiP) and Fla/(Fla + Pyr) ratios suggested that atmospheric PAHs from urban and rural sites were mainly associated with emissions from biomass burning, coal burning and petroleum combustion. However, the contribution of biomass burning increased at remote sites. Similar compositions of PAHs were found at three remote sites located on both sides of the Himalayas (Jomsom, Zhongba, and Nyalam), suggesting that the northern side of the Himalayas may be affected by anthropogenic emissions from the Indo-Gangetic Plain (IGP) via long-range atmospheric transport. This work provides a database of PAHs in central Himalayas for further assessing environmental risk of air pollution in the remote regions.

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“…1.4 µg m −3 at Qomolangma, Mt Everest, 4276 m a.s.l., by Cong et al, 2015 and 4 µg m −3 at the NW Pacific, 2-6.5 km column by Heald et al, 2005). FT-PM T OC under SAL conditions (0.77 µg m −3 ) was higher than under WES (0.52 µg m −3 , including the BBE) events.…”

Section: Fraction Determined Of Ommentioning

confidence: 96%

“…Succinic (suc) and phthalic (pth) acids were the most abundant dicarboxylic acids (Table 2) with FT and BL average values (suc: 6.5-3.7; pth: 3.2-2.8 ng m −3 for the FT-BL) much lower than those found for PM 2.5 in the FT Mount Tai (suc: 30 ng m −3 ; Wang et al, 2009), similar to those observed in PM T in the Himalayas (4276 m a.s.l.) (suc: 13.7; pth: 9.5 ng m −3 ; Cong et al, 2015), but higher than those detected in the North Pacific for remote marine PM T (suc: 2.8; pth: 0.66 ng m −3 ; Kawamura and Sakaguchi, 1999). Malic acid within the BL (the third most abundant polyacid at Izaña; Table 2) might be photochemical in origin via OH oxidation of the surrounding biogenic compounds transported by the daytime upslope winds.…”

Section: Dicarboxylic Acidsmentioning

confidence: 99%

Speciation of organic aerosols in the Saharan Air Layer and in the free troposphere westerlies

García¹,

Drooge²,

Rodrı́guez³

et al. 2017

Atmos. Chem. Phys.

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Abstract. We focused this research on the composition of the organic aerosols transported in the two main airflows of the subtropical North Atlantic free troposphere: (i) the Saharan Air Layer -the warm, dry and dusty airstream that expands from North Africa to the Americas at subtropical and tropical latitudes -and (ii) the westerlies, which flow from North America over the North Atlantic at mid-and subtropical latitudes. We determined the inorganic compounds (secondary inorganic species and elemental composition), elemental carbon and the organic fraction (bulk organic carbon and organic speciation) present in the aerosol collected at Izaña Observatory, ∼ 2400 m a.s.l. on the island of Tenerife. The concentrations of all inorganic and almost all organic compounds were higher in the Saharan Air Layer than in the westerlies, with bulk organic matter concentrations within the range 0.02-4.0 µg m −3 . In the Saharan Air Layer, the total aerosol population was by far dominated by dust (93 % of bulk mass), which was mixed with secondary inorganic pollutants (< 5 %) and organic matter (∼ 1.5 %). The chemical speciation of the organic aerosols (levoglucosan, dicarboxylic acids, saccharides, n-alkanes, hopanes, polycyclic aromatic hydrocarbons and those formed after oxidation of α-pinene and isoprene, determined by gas chromatography coupled with mass spectrometry) accounted for 15 % of the bulk organic matter (determined by the thermooptical transmission technique); the most abundant organic compounds were saccharides (associated with surface soils), secondary organic aerosols linked to oxidation of biogenic isoprene (SOA ISO) and dicarboxylic acids (linked to several primary sources and SOA). When the Saharan Air Layer shifted southward, Izaña was within the westerlies stream and organic matter accounted for ∼ 28 % of the bulk mass of aerosols. In the westerlies, the organic aerosol species determined accounted for 64 % of the bulk organic matter, with SOA ISO and dicarboxylic acids being the most abundant; the highest concentration of organic matter (3.6 µg m −3 ) and of some organic species (e.g. levoglucosan and some dicarboxylic acids) were associated with biomass burning linked to a fire in North America. In the Saharan Air Layer, the correlation found between SOA ISO and nitrate suggests a large-scale impact of enhancement of the formation rate of secondary organic aerosols due to interaction with anthropogenic NO x emissions.

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Carbonaceous aerosols on the south edge of the Tibetan Plateau: concentrations, seasonality and sources

Cited by 239 publications

References 57 publications

Black carbon and mineral dust in snow cover on the Tibetan Plateau

Black carbon and mineral dust in snow cover on the Tibetan Plateau

Characteristics of Particulate-Phase Polycyclic Aromatic Hydrocarbons (PAHs) in the Atmosphere over the Central Himalayas

Speciation of organic aerosols in the Saharan Air Layer and in the free troposphere westerlies

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