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

Abstract. To quantitatively evaluate the effect of carbonaceous aerosols on the south edge of the Tibetan Plateau, aerosol samples were collected weekly from August 2009 to July 2010 at Qomolangma (Mt. Everest) Station for Atmospheric and Environmental Observation and Research (QOMS, 28.36° N, 86.95° E, 4276 m a.s.l.). The average concentrations of organic carbon (OC), elemental carbon (EC) and water-soluble organic carbon were 1.43, 0.25 and 0.77 μg m−3, respectively. The concentration levels of OC and EC at QOMS are comparable to those at high-elevation sites on the southern slopes of the Himalayas (Langtang and Nepal Climate Observatory at Pyramid, or NCO-P), but 3 to 6 times lower than those at Manora Peak, India, and Godavari, Nepal. Sulfate was the most abundant anion species followed by nitrate, accounting for 25 and 12% of total ionic mass, respectively. Ca2+ was the most abundant cation species (annual average of 0.88 μg m−3). The dust loading, represented by Ca2+ concentration, was relatively constant throughout the year. OC, EC and other ionic species (NH4+, K+, NO3− and SO42−) exhibited a pronounced peak in the pre-monsoon period and a minimum in the monsoon season, being similar to the seasonal trends of aerosol composition reported previously from the southern slope of the Himalayas, such as Langtang and NCO-P. The strong correlation of OC and EC in QOMS aerosols with K+ and levoglucosan indicates that they mainly originated from biomass burning. The fire spots observed by MODIS and backward air-mass trajectories further demonstrate that in pre-monsoon season, agricultural and forest fires in northern India and Nepal were most likely sources of carbonaceous aerosol at QOMS. Moreover, the CALIOP observations confirmed that air-pollution plumes crossed the Himalayas during this period. The highly coherent variation of daily aerosol optical depth (500 nm) between QOMS and NCO-P indicates that both slopes of the Himalayas share a common atmospheric environment regime. In addition to large-scale atmospheric circulation, the unique mountain/valley breeze system can also have an important effect on air-pollutant transport.

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

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-14-25051-2014 ◽

2014 ◽

Vol 14 (18) ◽

pp. 25051-25082 ◽

Cited By ~ 5

Author(s):

Z. Cong ◽

S. Kang ◽

K. Kawamura ◽

B. Liu ◽

X. Wan ◽

...

Keyword(s):

Tibetan Plateau ◽

Organic Carbon ◽

Monsoon Season ◽

Air Pollutant ◽

Water Soluble ◽

Atmospheric Environment ◽

The Tibetan Plateau ◽

Carbonaceous Aerosols ◽

The South ◽

Aerosol Composition

Abstract. To quantitatively evaluate the effect of carbonaceous aerosols on the south edge of the Tibetan Plateau, aerosol samples were collected weekly from August 2009 to July 2010 at Mt. Everest (Qomolangma Station for Atmospheric and Environmental Observation and Research, briefly QOMS, 28.36° N, 86.95° E, 4276 m a.s.l.). The samples were analyzed for organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC) and major ions. The average concentrations of OC, EC and WSOC were 1.43, 0.25 and 0.77 μg m−3, respectively. The concentration levels of OC and EC at QOMS are comparable to those at high elevation sites on the southern slopes of the Himalayas (Langtang and NCO-P), but three to six times lower than those at Manora Peak, India and Godavari, Nepal. Sulfate was the most abundant anion species followed by nitrate, accounting for 25 and 12% of total ionic mass, respectively. Ca2+ was the most abundant cation species (annual average of 0.88 μg m−3). The various aerosol compositions showed distinctive seasonality. The dust loading, represented by Ca2+ concentration, was relatively constant throughout the year. While OC, EC and other ionic species (NH4+, K+, NO3−, and SO42−) exhibited a pronounced peak in the pre-monsoon period and a minimum in the monsoon season. Similar seasonal trends of aerosol composition were also reported previously from the southern slope of the Himalayas, such as Langtang and NCO-P. This phenomenon indicates that both slopes of Himalayas share a common atmospheric environment regime. The strong correlation of OC and EC in QOMS aerosols with K+ and levoglucosan indicates that they were mainly originated from biomass burning. The active fire spots observed by MODIS and their backward trajectories further demonstrate that in pre-monsoon season, agricultural and forest fires in the northern India and Nepal were most likely sources of carbonaceous aerosol at QOMS. In addition to large-scale atmospheric circulation, the unique mountain/valley breeze system in the Himalayas can also have an important effect on air pollutant transport.

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Size-Segregated Characteristics of Carbonaceous Aerosols during the Monsoon and Non-Monsoon Seasons in Lhasa in the Tibetan Plateau

Atmosphere ◽

10.3390/atmos10030157 ◽

2019 ◽

Vol 10 (3) ◽

pp. 157 ◽

Cited By ~ 2

Author(s):

Nannan Wei ◽

Chulei Ma ◽

Junwen Liu ◽

Guanghua Wang ◽

Wei Liu ◽

...

Keyword(s):

Tibetan Plateau ◽

Organic Carbon ◽

Size Distribution ◽

Fossil Fuels ◽

Monsoon Season ◽

Water Soluble ◽

Atmospheric Particulate Matter ◽

The Tibetan Plateau ◽

Carbonaceous Aerosols ◽

Different Diameters

In this paper, we intensively collected atmospheric particulate matter (PM) with different diameters (size ranges: <0.49, 0.49–0.95, 0.95–1.5, 1.5–3.0, 3.0–7.2, and >7.2 μm) in Lhasa during the monsoon and non-monsoon seasons. The results clearly showed that the concentrations of PM, organic carbon (OC), elemental carbon (EC), and water-soluble organic carbon (WSOC) during the non-monsoon season were much higher than the concentrations during the monsoon season. During the monsoon season, a bimodal size distribution of the OC and WSOC, which were at <0.49 μm and >7.2 μm, respectively, and a unimodal size distribution at <0.49 μm for the EC were observed. However, during the non-monsoon season, there was a trimodal size distribution of the OC and WSOC (<0.49 μm, 1.5–3.0 μm, and >7.2 μm), and a unimodal size distribution of the EC (<0.49 μm). Possible sources of the carbonaceous components were revealed by combining the particle size distribution and the correlation analysis. OC, EC, and WSOC were likely from the photochemical transformation of biogenic and anthropogenic VOC, and the incomplete combustion of biomass burning and fossil fuels at <0.49 μm, whilst they were also likely to be from various types of dust and biogenic aerosols at >7.2 μm. OC and WSOC at 1.5–3.0 μm were likely to have been from the burning of yak dung and photochemical formation. The above results may draw attention in the public and scientific communities to the issues of air quality in the Tibetan Plateau.

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Spatio-temporal variability and light absorption property of carbonaceous aerosol in a typical glacierization region of the Tibetan Plateau

10.5194/acp-2017-865 ◽

2017 ◽

Author(s):

Hewen Niu ◽

Shichang Kang ◽

Hailong Wang ◽

Rudong Zhang ◽

Xixi Lu ◽

...

Keyword(s):

Tibetan Plateau ◽

East Asia ◽

Monsoon Season ◽

The Tibetan Plateau ◽

Carbonaceous Aerosols ◽

Carbonaceous Matter ◽

Near Surface ◽

Post Monsoon ◽

Local Sources ◽

Post Monsoon Season

Abstract. The high altitude glacierized regions of the Tibetan Plateau (TP) are influenced by carbonaceous aerosols from local sources and long range transport from the adjoining areas. Deposition and accumulation of light-absorbing carbonaceous matters on glacier surfaces can alter the energy balance of glaciers. In this study, two years (December 2014 to December 2016) of continuous observations of carbonaceous aerosols performed in glacierized region of Mt. Yulong (4510 m a.s.l.) and Ganhaizi (GHZ) basin (3054 m a.s.l.) are analyzed. The mass absorption efficiency (MAE) of black carbon (BC) was determined for the first time in Mt. Yulong using a thermal-optical carbon analyzer. The average BC and organic carbon (OC) concentrations were 1.51 ± 0.93 and 2.57 ± 1.32 μg m−3, respectively. The average SOC (secondary OC) concentration, quantified using BC-tracer method, was 1.67 ± 1.15 μg m−3. Monthly mean BC concentrations from monsoon to post-monsoon season were higher than OC in the high altitudes (approximately 5000 m a.s.l.) of Mt. Yulong. The concentrations of carbonaceous matter have distinct spatial and inter-annual variations in this glacierization area. High carbonaceous matter associated with OC (including both SOC and POC) in GHZ basin was mainly contributed from tour bus emissions. The annual mean OC / BC ratio was 2.45 ± 1.96 in Mt. Yulong. Strong photochemical reactions and local tourism activities in monsoon season were the main factors inducing high OC / BC ratios in the Mt. Yulong region. The mean MAE of BC, measured at 632 nm with a thermal-optical protocol under the filter-based method, was 6.82 ± 0.73 m2 g−1, comparable with the results from other studies. Strong seasonal and spatial variations of BC MAE were largely related to the OC and SOC abundance. Source attribution analysis using a global aerosol-climate model, equipped with a BC source tagging technique, suggests that East Asia emissions, including local sources, have the dominant contribution (over 50 %) to annual mean near-surface BC at the two sites. There is also a strong seasonal variation in the regional source apportionment. South Asia has the largest contribution during the pre-monsoon season, while East Asia dominates the monsoon season and post-monsoon season. Results in this study have great implications for accurately evaluating the influences of carbonaceous matter on glacial melting and water resource supply in glacierization areas.

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Light absorption and fluorescence characteristics of water-soluble organic compounds in carbonaceous particles at a typical remote site in the southeastern Himalayas and Tibetan Plateau

10.5194/egusphere-egu21-3653 ◽

2021 ◽

Author(s):

Chao Zhang ◽

Meilian Chen ◽

Shichang Kang ◽

Fangping Yan ◽

Chaoliu Li

Keyword(s):

Tibetan Plateau ◽

Organic Carbon ◽

South Asia ◽

Light Absorption ◽

Fluorescence Analysis ◽

Water Soluble ◽

The Tibetan Plateau ◽

Remote Site ◽

Carbonaceous Particles ◽

Fluorescence Characteristics

Carbonaceous particles play an important role in climate change, and the increase in their emission and deposition causes glacier melting in the Himalayas and the Tibetan Plateau (HTP). This implies that studying their basic characteristics is crucial for a better understanding of the climate forcing observed in this area. Thus, we investigated characteristics of carbonaceous particles at Yaze village, a typical remote site of southeastern HTP.&#160; The results showed that the organic carbon and elemental carbon concentrations at this study site were 1.86 &#177; 0.84 and 0.18 &#177; 0.09 &#956;g m-3, respectively, which were much lower than those reported for other frequently monitored stations in the same region. Thus, these values reflect the background characteristics of the study site. Additionally, the absorption coefficient per mass (&#945;/&#961;) of water-soluble organic carbon (WSOC) at 365 nm was 0.60 &#177; 0.19 m2 g-1, which was lower than those reported for other remote stations in the HTP. This value could be attributed to a lower and higher contribution of mineral dust and secondary organic carbon, respectively. Multi-dimensional fluorescence analysis showed that the WSOC consisted of approximately 37% and 63% protein and humic-like components, respectively, and the latter was identified as the determining component of light absorption ability of the WSOC. Combined the significant relationships between WSOC and sulfate ion, potassium ion, and nitrate ion with the air masses at the study site originated primarily from South Asia, it is suggested that the levels of carbonaceous particles in Yaze village were predominantly influenced by emissions from South Asia.

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Correction: Aged dissolved organic carbon exported from rivers of the Tibetan Plateau

PLoS ONE ◽

10.1371/journal.pone.0181295 ◽

2017 ◽

Vol 12 (7) ◽

pp. e0181295 ◽

Cited By ~ 1

Author(s):

Bin Qu ◽

Mika Sillanpää ◽

Chaoliu Li ◽

Shichang Kang ◽

Aron Stubbins ◽

...

Keyword(s):

Tibetan Plateau ◽

Organic Carbon ◽

Dissolved Organic Carbon ◽

The Tibetan Plateau

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The Role of Shallow Convection over the Tibetan Plateau

Journal of Climate ◽

10.1175/jcli-d-16-0599.1 ◽

2017 ◽

Vol 30 (15) ◽

pp. 5791-5803 ◽

Cited By ~ 7

Author(s):

Yunying Li ◽

Minghua Zhang

Keyword(s):

Tibetan Plateau ◽

Large Scale ◽

Diabatic Heating ◽

Middle Atmosphere ◽

Atmospheric Environment ◽

Monsoon Circulation ◽

The Tibetan Plateau ◽

Shallow Convection ◽

Sensitivity Experiment ◽

Stratiform Clouds

Cumulus (Cu) from shallow convection is one of the dominant cloud types over the Tibetan Plateau (TP) in the summer according to CloudSat– CALIPSO observations. Its thermodynamic effects on the atmospheric environment and impacts on the large-scale atmospheric circulation are studied in this paper using the Community Atmospheric Model, version 5.3 (CAM5.3). It is found that the model can reasonably simulate the unique distribution of diabatic heating and Cu over the TP. Shallow convection provides the dominant diabatic heating and drying to the lower and middle atmosphere over the TP. A sensitivity experiment indicates that without Cu over the TP, large-scale condensation and stratiform clouds would increase dramatically, which induces enhanced low-level wind and moisture convergence toward the TP, resulting in significantly enhanced monsoon circulation with remote impact on the areas far beyond the TP. Cu therefore acts as a safety valve to modulate the atmospheric environment that prevents the formation of superclusters of stratiform clouds and precipitation over the TP.

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Potential Production of Carbon Gases and Their Responses to Paleoclimate Conditions: An Example From Xiaolongtan Basin, Southeast Tibetan Plateau

Frontiers in Earth Science ◽

10.3389/feart.2021.582062 ◽

2021 ◽

Vol 9 ◽

Author(s):

Gen Wang ◽

Yongli Wang ◽

Zhifu Wei ◽

Zepeng Sun ◽

Wei He ◽

...

Keyword(s):

Organic Matter ◽

Tibetan Plateau ◽

Low Temperature ◽

Organic Carbon ◽

Carbon Cycle ◽

Higher Plants ◽

The Tibetan Plateau ◽

Climate Conditions ◽

Burial Flux ◽

Carbon Gases

Uplift of the Tibetan Plateau plays a significant and lasting role in the variations of climate conditions and global carbon cycle. However, our knowledge is limited due to the lack of long-sequence records revealing rates of CO2 and CH4 production, hampering our understanding of the relationship between paleoclimatic conditions, carbon cycling and greenhouse gas flux. Here, we present a combination of paleoclimate records and low-temperature thermal simulation results from sediments of the Xiaolongtan Basin at the southeastern margin of the Qinghai-Tibetan Plateau, spanning the late Miocene (14.1 ∼ 11.6 Ma). The n-alkane-derived proxies suggested that the sources of organic matter were obviously different: a mixed source including lower organisms and terrestrial higher plants for the Dongshengqiao Formation from 14.1 to 12.6 Ma, and a predominant contribution from terrestrial higher plants for Xiaolongtan Formation between 12.6 and 11.6 Ma. The paleoclimate was generally warm and humid as reflected by the lipid biomarkers, consistent with previous studies. In addition, the carbon gases (including CO2 and hydrocarbon gases) generated by the low-temperature thermal simulation experiments indicated a production rate of CO2 and CH4 were as high as 88,000 ml/kg rock and 4,000 ml/kg rock, respectively, implying there were certain amounts of carbon gases generated and released into the atmosphere during their shallow burial stage. Besides, the calculated production rate of carbon gases and the estimated burial flux of organic carbon varied in response to the variations of paleoclimate conditions. Based on these observations, we propose that the climate conditions predominantly controlled the formation and accumulation of organic matter, which consequently affected the production of carbon gases and burial flux of organic carbon. The results presented here may provide a significant insight into the carbon cycle in the southeast of the Tibetan Plateau.

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Characteristics, seasonality and sources of carbonaceous and ionic components in the tropical Indian aerosols

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-11-3937-2011 ◽

2011 ◽

Vol 11 (2) ◽

pp. 3937-3976 ◽

Cited By ~ 1

Author(s):

C. M. Pavuluri ◽

K. Kawamura ◽

S. G. Aggarwal ◽

T. Swaminathan

Keyword(s):

Organic Carbon ◽

Atmospheric Aerosols ◽

Atmospheric Transport ◽

Indian Subcontinent ◽

Ionic Species ◽

Water Soluble ◽

Carbonaceous Aerosols ◽

Mass Fractions ◽

High Concentrations ◽

Ionic Components

Abstract. To better characterize South and Southeast Asian aerosols, PM10 samples collected from tropical Chennai, India (13.04° N; 80.17° E) were analyzed for carbonaceous and water-soluble ionic components. Concentration ranges of elemental carbon (EC) and organic carbon (OC) were 2.4–14 μg m−3 and 3.2–15.6 μg m−3 in winter samples whereas they were 1.1–2.5 μg m−3 and 4.1–17.6 μg m−3 in summer samples, respectively. Concentration of secondary organic carbon (SOC) retrieved from EC-tracer method was 4.6 ± 2.8 μg m−3 in winter and 4.3 ± 2.8 μg m−3 in summer. SO42- (8.8 ± 2.5 μg m−3 and 4.1 ± 2.7 μg m−3 in winter and summer, respectively) was found as the most abundant ionic species (57% on average, n = 49), followed by NH4+ (15%) > NO3− > Cl− > K+> Na+ > Ca2+ > MSA− > Mg2+. The mass fractions of EC, organic matter (OM) and ionic species varied seasonally, following the air mass trajectories and corresponding source strength. Based on mass concentration ratios of selected components and relations of EC and OC to marker species, we found that biofuel/biomass burning is the major source of atmospheric aerosols in South and Southeast Asia. The high concentrations of SOC and WSOC/OC ratios (ave. 0.45; n = 49) as well as good correlations between SOC and WSOC suggest that the secondary production of organic aerosols during long-range atmospheric transport is also significant in this region. This study provides the baseline data of carbonaceous aerosols for southern part of the Indian subcontinent.

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The South Asia Monsoon Break Promotes Grass Growth on the Tibetan Plateau

10.5194/egusphere-egu21-5776 ◽

2021 ◽

Author(s):

Yanghang Ren ◽

Kun Yang ◽

Han Wang

Keyword(s):

Soil Moisture ◽

Tibetan Plateau ◽

Solar Radiation ◽

Climate Variability ◽

South Asia ◽

The Tibetan Plateau ◽

The South ◽

Central Eastern ◽

Grass Growth ◽

The Impact

As region that is highly sensitive to global climate change, the Tibetan Plateau (TP) experiences an intra-seasonal soil water deficient due to the reduced precipitation during the South Asia monsoon (SAM) break. Few studies have investigated the impact of the SAM break on TP ecological processes, although a number of studies have explored the effects of inter-annual and decadal climate variability. In this study, the response of vegetation activity to the SAM break was investigated. The data used are: (1) soil moisture from in situ, satellite remote sensing and data assimilation; and (2) the Normalized Difference Vegetation Index (NDVI) and Solar-Induced chlorophyll Fluorescence&#160;(SIF). We found that in the region impacted by SAM break, which is distributed in the central-eastern part of TP, photosynthesis become more active during the SAM break. And temporal variability in the photosynthesis of this region is controlled mainly by solar radiation variability and has little sensitivity to soil moisture. We adopted a diagnostic process-based modeling approach to examine the causes of enhanced plant activity during the SAM break on the central-eastern TP. Our analysis indicates that active photosynthetic behavior in the reduced precipitation is stimulated by increases in solar radiation absorbed and temperature. This study highlights the importance of sub-seasonal climate variability for characterizing the relationship between vegetation and climate.

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Investigation of atmospheric aerosols over semi-urban and urban areas in Eastern Indo-Gangetic Plain: seasonal variability and source apportionment using PMF

10.5194/egusphere-egu21-14205 ◽

2021 ◽

Author(s):

Kanishtha Dubey ◽

Shubha Verma

Keyword(s):

Organic Carbon ◽

Biomass Burning ◽

Atmospheric Aerosols ◽

Urban Areas ◽

Relative Concentration ◽

Road Dust ◽

Water Soluble ◽

Carbonaceous Aerosols ◽

Gangetic Plain ◽

Brick Kilns

The study investigates the chemical composition and source of aerosol origin at a semi-urban (Kharagpur&#8211;Kgp) and urban (Kolkata&#8211;Kol) region during the period February 2015 to January 2016 and September 2010 to August 2011 respectively. Major water-soluble inorganic aerosols (WSII) were determined using Ion chromatography and carbonaceous aerosols (CA) using OC&#8211;EC analyser. A multivariate factor analysis Positive Matrix Factorization (PMF) was used in resolving source of aerosols at the study locations. Seasonal analysis of WSII at Kgp and Kol indicated relative dominance of calcium at both the places followed by sodium, chloride, and magnesium ions. Non-sea salt potassium (nss&#8211;K+), a biomass burning tracer was found higher at Kol than at Kgp. Sum of secondary aerosols sulphate (SO42-), nitrate (NO3-) and ammonium (NH4+) was higher at Kol than Kgp with relative concentration of SO42- being higher than NO3- at Kgp which was vice-versa at Kol. Examination of carbonaceous aerosols showed three times higher concentration of organic carbon (OC) than elemental carbon (EC) with monthly mean of OC/EC ratio > 2, indicating likely formation of secondary organic carbon formation. Seasonal influence of biomass burning inferred from nss&#8211;K+ (OC/EC) ratio relationship indicated dissimilarity in seasonality of biomass burning at Kgp (Kol). PMF resolved sources for Kgp constituted of secondary aerosol emissions, biomass burning, fugitive dust, marine aerosols, crustal dust and emissions from brick kilns while for Kol factors constituted of burning of waste, resuspended paved road dust, coal combustion, sea spray aerosols, vehicular emissions and biomass burning.

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