Quantitative analysis of lake area variations and the influence factors from 1971 to 2004 in the Nam Co basin of the Tibetan Plateau

Abstract. Atmospheric processes (air-surface exchange, and atmospheric deposition and degradation) are crucial for understanding the global cycling and fate of persistent organic pollutants (POPs). However, such assessment over the Tibetan Plateau (TP) remains uncertain. More than 50 % of the Chinese lakes are located on the TP, which exerts a remarkable influence on the regional water, energy, and chemical cycling. In this study, air and water samples were simultaneously collected in Nam Co, a large lake on the TP, to test whether the lake is a "secondary source" or "sink" of POPs. Lower concentrations of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) were observed in the atmosphere and lake water of Nam Co, while the levels of polycyclic aromatic hydrocarbons (PAHs) were relatively higher. Results of fugacity ratios and chiral signatures both suggest that the lake acted as the net sink of atmospheric hexachlorocyclohexanes (HCHs), following their long-range transport driven by the Indian Monsoon. Different behaviors were observed in the PAHs, which primarily originated from local biomass burning. Acenaphthylene, acenaphthene, and fluorene showed volatilization from the lake to the atmosphere; while other PAHs were deposited into the lake due to the integrated deposition process (wet/dry and air-water gas deposition) and limited atmospheric degradation. As the dominant PAH compound, phenanthrene exhibited a seasonal reversal of air-water gas exchange, which was likely related to the melting of the lake ice in May. The annual input of HCHs from air to the entire lake area (2015 km2) was estimated as 1.9 kg year−1, while those estimated for PAHs can potentially reach up to 550 kg year−1. This study highlights the significance of PAH deposition on the regional carbon cycling in the oligotrophic lakes of the TP.

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Atmospheric processes of organic pollutants over a remote lake on the central Tibetan Plateau: implications for regional cycling

Atmospheric Chemistry and Physics ◽

10.5194/acp-17-1401-2017 ◽

2017 ◽

Vol 17 (2) ◽

pp. 1401-1415 ◽

Cited By ~ 16

Author(s):

Jiao Ren ◽

Xiaoping Wang ◽

Chuanfei Wang ◽

Ping Gong ◽

Tandong Yao

Keyword(s):

Tibetan Plateau ◽

Organic Pollutants ◽

Deposition Process ◽

Secondary Source ◽

The Tibetan Plateau ◽

Lake Area ◽

Nam Co ◽

Surface Exchange ◽

Atmospheric Processes ◽

Water Gas

Abstract. Atmospheric processes (air–surface exchange, and atmospheric deposition and degradation) are crucial for understanding the global cycling and fate of organic pollutants (OPs). However, such assessments over the Tibetan Plateau (TP) remain uncertain. More than 50 % of Chinese lakes are located on the TP, which exerts a remarkable influence on the regional water, energy, and chemical cycling. In this study, air and water samples were simultaneously collected in Nam Co, a large lake on the TP, to test whether the lake is a secondary source or sink of OPs. Lower concentrations of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) were observed in the atmosphere and lake water of Nam Co, while the levels of polycyclic aromatic hydrocarbons (PAHs) were relatively higher. Results of fugacity ratios and chiral signatures both suggest that the lake acted as the net sink of atmospheric hexachlorocyclohexanes (HCHs), following their long-range transport driven by the Indian monsoon. Different behaviours were observed in the PAHs, which primarily originated from local biomass burning. Acenaphthylene, acenaphthene, and fluorene showed volatilization from the lake to the atmosphere, while other PAHs were deposited into the lake due to the integrated deposition process (wet/dry and air–water gas deposition) and limited atmospheric degradation. As the dominant PAH compound, phenanthrene exhibited a seasonal reversal of air–water gas exchange, which was likely related to the melting of the lake ice in May. The annual input of HCHs from the air to the entire lake area (2015 km2) was estimated as 1.9 kg yr−1, while input estimated for ∑ 15PAHs can potentially reach up to 550 kg yr−1. This study highlights the significance of PAH deposition on the regional carbon cycling in the oligotrophic lakes of the TP.

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Interrelation among climate factors, snow cover, grassland vegetation, and lake in the Nam Co basin of the Tibetan Plateau

Journal of Applied Remote Sensing ◽

10.1117/1.jrs.8.084694 ◽

2014 ◽

Vol 8 (1) ◽

pp. 084694 ◽

Cited By ~ 8

Author(s):

Siyu Chen ◽

Tiangang Liang ◽

Hongjie Xie ◽

Qisheng Feng ◽

Xiaodong Huang ◽

...

Keyword(s):

Tibetan Plateau ◽

Snow Cover ◽

The Tibetan Plateau ◽

Climate Factors ◽

Nam Co ◽

Grassland Vegetation ◽

Nam Co Basin

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Temporal and Spatial Aspects of Snow Distribution in the Nam Co Basin on the Tibetan Plateau from MODIS Data

Remote Sensing ◽

10.3390/rs2122700 ◽

2010 ◽

Vol 2 (12) ◽

pp. 2700-2712 ◽

Cited By ~ 18

Author(s):

Jan Kropacek ◽

Chen Feng ◽

Markus Alle ◽

Shichang Kang ◽

Volker Hochschild

Keyword(s):

Tibetan Plateau ◽

The Tibetan Plateau ◽

Nam Co ◽

Modis Data ◽

Snow Distribution ◽

Temporal And Spatial ◽

Nam Co Basin

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Hydrological system analysis and modelling of the Nam Co basin in Tibet

Advances in Geosciences ◽

10.5194/adgeo-27-29-2010 ◽

2010 ◽

Vol 27 ◽

pp. 29-36 ◽

Cited By ~ 59

Author(s):

P. Krause ◽

S. Biskop ◽

J. Helmschrot ◽

W.-A. Flügel ◽

S. Kang ◽

...

Keyword(s):

Tibetan Plateau ◽

Water Balance ◽

Lake Level ◽

Global Climate ◽

The Tibetan Plateau ◽

Nam Co ◽

Ice Melt ◽

Hydrological System ◽

Nam Co Basin ◽

Snow And Ice Melt

Abstract. The Tibetan Plateau and the adjacent high mountain regions of the Himalayas play an important role in the global climate dynamic through its impact on the Asian monsoon system, which in turn is impacting the water resources of this extremely vulnerable region. To provide further knowledge about the changing impact of rainfall patterns, spatial and temporal variability of snow cover contribution, amount of snow and ice melt runoff, evapotranspiration as well as dynamics of wetlands and permafrost water balance studies are required. This is of particular importance in terms of global climate change because of a severe gap in the knowledge of the short, mid and long term implications on the hydrological system. This study concentrates on the macroscale catchment of the lake Nam Co, located at 4718 m a.s.l. at the foot of the Nyainqentanglha Mountains in central Tibet (30° N, 90° E). The water balance of the Nam Co basin is dominated by semi-arid climate, snow and ice melt runoff and high evaporation rates due to the high radiation input and the low air humidity. The observed temperature rise, glacier retreat, permafrost decay and lake level increase indicate significant system changes and the high sensitivity of the Tibetan Plateau on global warming. The development of a suitable water balance model and its preliminary application was the main objective of this study. The development was done with the Jena Adaptable Modelling System JAMS along with existing scientific process components of the J2000 module library which were partly further developed to reflect the specific conditions of the high elevation Nam Co basin. The preliminary modelling exercise based on gridded data from a downscaled ECHAM5 data set provided reasonable estimates about the important hydrological water balance components of the Nam Co basin. With the modelling results the observed lake level rise could be reproduced and it could be shown that the runoff from the glaciered areas seems to be the most important component to explain the increasing amount of lake water.

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Contrasting Evolution Patterns of Endorheic and Exorheic Lakes on the Central Tibetan Plateau and Climate Cause Analysis during 1988–2017

Water ◽

10.3390/w13141962 ◽

2021 ◽

Vol 13 (14) ◽

pp. 1962

Author(s):

Zhilong Zhao ◽

Yue Zhang ◽

Zengzeng Hu ◽

Xuanhua Nie

Keyword(s):

Climate Change ◽

Tibetan Plateau ◽

Climatic Factors ◽

Global Climate ◽

Rapid Expansion ◽

Annual Precipitation ◽

The Tibetan Plateau ◽

Lake Area ◽

Climate Change Research ◽

Mean Temperature

The alpine lakes on the Tibetan Plateau (TP) are indicators of climate change. The assessment of lake dynamics on the TP is an important component of global climate change research. With a focus on lakes in the 33° N zone of the central TP, this study investigates the temporal evolution patterns of the lake areas of different types of lakes, i.e., non-glacier-fed endorheic lakes and non-glacier-fed exorheic lakes, during 1988–2017, and examines their relationship with changes in climatic factors. From 1988 to 2017, two endorheic lakes (Lake Yagenco and Lake Zhamcomaqiong) in the study area expanded significantly, i.e., by more than 50%. Over the same period, two exorheic lakes within the study area also exhibited spatio-temporal variability: Lake Gaeencuonama increased by 5.48%, and the change in Lake Zhamuco was not significant. The 2000s was a period of rapid expansion of both the closed lakes (endorheic lakes) and open lakes (exorheic lakes) in the study area. However, the endorheic lakes maintained the increase in lake area after the period of rapid expansion, while the exorheic lakes decreased after significant expansion. During 1988–2017, the annual mean temperature significantly increased at a rate of 0.04 °C/a, while the annual precipitation slightly increased at a rate of 2.23 mm/a. Furthermore, the annual precipitation significantly increased at a rate of 14.28 mm/a during 1995–2008. The results of this study demonstrate that the change in precipitation was responsible for the observed changes in the lake areas of the two exorheic lakes within the study area, while the changes in the lake areas of the two endorheic lakes were more sensitive to the annual mean temperature between 1988 and 2017. Given the importance of lakes to the TP, these are not trivial issues, and we now need accelerated research based on long-term and continuous remote sensing data.

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Surface ozone at Nam Co (4730 m a.s.l.) in the inland Tibetan Plateau: variation, synthesis comparison and regional representativeness

10.5194/acp-2017-175 ◽

2017 ◽

Cited By ~ 1

Author(s):

Xiufeng Yin ◽

Shichang Kang ◽

Benjamin de Foy ◽

Zhiyuan Cong ◽

Jiali Luo ◽

...

Keyword(s):

Tibetan Plateau ◽

Surface Ozone ◽

Early Morning ◽

Photochemical Reactions ◽

Transport Processes ◽

The Tibetan Plateau ◽

Nam Co ◽

Mixing Ratios ◽

Northern Tibetan Plateau ◽

Ozone Levels

Abstract. Ozone is an important pollutant and greenhouse gas, and tropospheric ozone variations are generally associated with both natural and anthropogenic processes. As one of the most pristine and inaccessible regions in the world, the Tibetan Plateau has been considered as an ideal region for studying processes of the background atmosphere. Due to the vast area of the Tibetan Plateau, sites in the southern, northern and central regions exhibit different patterns of variation in surface ozone. Here, we present long-term measurements for ~ 5 years (January 2011 to October 2015) of surface ozone mixing ratios at Nam Co Station, which is a regional background site in the inland Tibetan Plateau. An average surface ozone mixing ratio of 47.6 ± 11.6 ppb was recorded, and a large annual cycle was observed with maximum ozone mixing ratios in the spring and minimum ratios during the winter. The diurnal cycle is characterized by a minimum in the early morning and a maximum in the late afternoon. Nam Co Station represents a background region where surface ozone receives negligible local anthropogenic emissions. Surface ozone at Nam Co Station is mainly dominated by natural processes involving photochemical reactions and potential local vertical mixing. Model results indicate that the study site is affected by the surrounding areas in different seasons and that air masses from the northern Tibetan Plateau lead to increased ozone levels in the summer. In contrast to the surface ozone levels at the edges of the Tibetan Plateau, those at Nam Co Station are less affected by stratospheric intrusions and human activities which makes Nam Co Station representative of vast background areas in the central Tibetan Plateau. By comparing measurements at Nam Co Station with those from other sites in the Tibetan Plateau and beyond, we aim to expand the understanding of ozone cycles and transport processes over the Tibetan Plateau. This work may provide a reference for model simulations in the future.

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Air-Lake Interaction Features Found in Heat and Water Exchanges over Nam Co on the Tibetan Plateau

SOLA ◽

10.2151/sola.2009-044 ◽

2009 ◽

Vol 5 ◽

pp. 172-175 ◽

Cited By ~ 47

Author(s):

Shigenori Haginoya ◽

Hideyuki Fujii ◽

Tsuneo Kuwagata ◽

Jianqing Xu ◽

Yasushi Ishigooka ◽

...

Keyword(s):

Tibetan Plateau ◽

The Tibetan Plateau ◽

Nam Co

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Variations in water level and glacier mass balance in Nam Co lake, Nyainqentanglha range, Tibetan Plateau, based on ICESat data for 2003-09

Annals of Glaciology ◽

10.3189/2014aog66a100 ◽

2014 ◽

Vol 55 (66) ◽

pp. 239-247 ◽

Cited By ~ 13

Author(s):

Hongbo Wu ◽

Ninglian Wang ◽

Xi Jiang ◽

Zhongming Guo

Keyword(s):

Tibetan Plateau ◽

Mass Balance ◽

Water Level ◽

Lake Level ◽

Altimeter Data ◽

Glacier Mass Balance ◽

Lake Area ◽

Nam Co ◽

Glacier Meltwater ◽

Nam Co Lake

AbstractWater level fluctuations of inland lakes are related to regional-scale climate changes, and reflect variations in evaporation, precipitation and glacier meltwater flowing into the lake area in its catchment. In this paper, Ice, Cloud and land Elevation Satellite (ICESat) altimeter data and Landsat imagery (2002-09) are used to estimate Nam Co lake (Nyainqentanglha range, Tibetan Plateau) water elevation changes during 2002-09. In 2003 Nam Co lake covered an area of ~1998.8 ± 4.2 km2 and was situated at 4723 m a.s.l. Over such inland water bodies, ICESat altimeter data offer both wide coverage and spatial and temporal accuracy. We combine remote-sensing and GIS technology to map and reconstruct lake area and increased volume changes during a 7 year time series. Nam Co lake water level increased by 2.4±0.12m (0.33ma–1) between 23 February 2003 and 1 October 2009, and lake volume increased by 4.9 ±0.5 km3. In the past 7 years, Nam Co lake area has increased from 1998.78 ±5.4 to 2023.8 ±3.4 km2, the glacier-covered area has decreased from 832.34 to 821.0 km2 and the drainage basin area has decreased from 201.1 ±4.2 to 196.1 ±2.3 km2. However, the most spectacular feature is the continual water level rise from 2003 to 2009 without an obvious associated increase in precipitation. Based on digital elevation models (DEMs) from Shuttle Radar Topography Mission (SRTM) DEM data and corrected ICESat elevation data, significant changes to glacier mass balance in the western Nyainqentanglha mountains are indicated. Nyainqentanglha mountain glacier surface elevations decreased by 8.39 ± 0.45 m during 2003-09. Over the same period, at least 1.01 km3 of glacial meltwater flowed into Nam Co lake, assuming a glacial runoff coefficient of 0.6. The mean glacier mass-balance value is -490mmw.e. over the corresponding period, indicating that glacier meltwater in the catchment contributes to lake level rise. The contribution rate of glacial meltwater to lake water volume rise is 20.75%. The temporal lake level fluctuation correlates with temperature variations over the same time span.

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