Abstract. Deposition and accumulation of light-absorbing carbonaceous aerosol on glacier surfaces can alter the energy balance of glaciers. In this study, 2 years (December 2014 to December 2016) of continuous observations of carbonaceous aerosols in the glacierized region of the Mt. Yulong and Ganhaizi (GHZ) basin are analyzed. The average elemental carbon (EC) and organic carbon (OC) concentrations were 1.51±0.93 and 2.57±1.32 µg m−3, respectively. Although the annual mean OC ∕ EC ratio was 2.45±1.96, monthly mean EC concentrations during the post-monsoon season were even higher than OC in the high altitudes (approximately 5000 ma.s.l.) of Mt. Yulong. Strong photochemical reactions and local tourism activities were likely the main factors inducing high OC ∕ EC ratios in the Mt. Yulong region during the monsoon season. The mean mass absorption efficiency (MAE) of EC, measured for the first time in Mt. Yulong, at 632 nm with a thermal-optical carbon analyzer using 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 EC MAE were largely related to the OC abundance. Source attribution analysis using a global aerosol–climate model, equipped with a black carbon (BC) source tagging technique, suggests that East Asia emissions, including local sources, have the dominant contribution (over 50 %) to annual mean near-surface BC in the Mt. Yulong area. There is also a strong seasonal variation in the regional source apportionment. South Asia has the largest contribution to near-surface BC 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.
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.
Atmospheric aerosols are a branch of active research in recent decades. The deposition of light-absorbing substances on high-altitude glaciers causes substantial adverse impacts on the cryospheric environment, cryosphere-hydrology, and climate system. Although, the concentrations of water-soluble organic carbon (WSOC) in snow/ice on glaciers of Tibetan Plateau (TP) have been reported, their transfer processes and optical properties in the context of summer precipitation-atmosphere-snow-river water continuum are seldom studied. In this study, we have systematically examined some scientific issues associated with WSOC concentrations and light absorption properties of WSOC in various forms of samples from the Mt. Yulong region. Statistical results demonstrate that the spatial distribution of WSOC in the snow of Baishui glacier was heterogeneous. The average WSOC concentrations of each snowpit were significantly decreased, and its light-absorbing properties were significantly elevated with the time extension. Aerosol WSOC concentrations and light absorption have distinct spatial disparity and seasonal variation. Pre-monsoon and monsoon have the highest and lowest WSOC content, respectively. Whereas the light-absorbing properties present contrasting seasonal trends. Rivers of which runoff was supplied by glacier meltwater have significantly lower WSOC concentrations (e.g., 0.42 ± 0.03 mg L-1) compared with other forms of water bodies. Mass absorption cross-section of WSOC (MAC-WSOC) in multiple snow and meltwater samples was significantly different and type-dependent. Atmospheric aerosol has the lowest MAC-WSOC value among the four types of samples, which was likely associated with exhaust emissions from private vehicles and tour buses. Statistical results indicated that the average AAE330-400 values of various snow/ice samples are subequal. Snow of glaciers supplies a desirable platform for the deposition of gaseous materials which experienced long-range transport in high altitude zones. Biomass-burning emissions made an immense contribution to the WSOC deposition over the study area, as demonstrated by the distribution of active fire points. However, this preliminary study represents the first systematic investigation of WSOC deposition in southeastern TP. Further robust in-situ field investigations and laboratory measurements are urgently necessary to improve our understanding of the transfer process and optical property of WSOC.
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