Delineation of a Quaternary Aquifer Using Integrated Hydrogeological and Geophysical Estimation of Hydraulic Conductivity on the Tibetan Plateau, China

Groundwater is the most unexplored element of the hydrologic cycle on the Tibetan Plateau (TP) due to harsh climate conditions. This study aims at delineating and characterizing the unexplored Zhanongtang–Ganmanong aquifer, situated in the Zhagu subcatchment of the Nam Co catchment, south-central TP. Multiple hydrogeophysical and lithological in situ field and laboratory methods are applied: depth-to-water-table measurements, grain size analysis, hydraulic empirical and field methods to estimate hydraulic conductivity (K), and analysis of electrical resistivity tomography profiles. Integration of these methods revealed the existence of a Quaternary hydrostratigraphic unit that was found to be unconsolidated, laterally heterogeneous and homogeneous over depth. The results revealed consistent K ranges of three K zones, which is in accordance with local lithology. The K ranges are applicable to other locations within the Nam Co catchment with similar lithology as in the study area without further field experiments. Permafrost was found to be absent in the study area ranging from 4730 m a.s.l. to 5200 m a.s.l. altitude. These results provide insight into the hydrogeological conditions of the TP and are useful for conceptual and numerical groundwater flow modeling to predict future changes of water fluxes and water budgets caused by climatic change, especially in remote areas.

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Grain-size analysis of Upper Pliocene red clay deposits from Linxia Basin: Implications for Asian monsoon evolution on the NE margin of the Tibetan Plateau

Palaeogeography Palaeoclimatology Palaeoecology ◽

10.1016/j.palaeo.2018.09.027 ◽

2018 ◽

Vol 511 ◽

pp. 597-605 ◽

Cited By ~ 2

Author(s):

Jinbo Zan ◽

Xiaojing Li ◽

Xiaomin Fang ◽

Weilin Zhang ◽

Maodu Yan ◽

...

Keyword(s):

Grain Size ◽

Tibetan Plateau ◽

Asian Monsoon ◽

Grain Size Analysis ◽

Size Analysis ◽

The Tibetan Plateau ◽

Red Clay ◽

Clay Deposits ◽

Linxia Basin

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What are the key drivers of regional differences in the water balance on the Tibetan Plateau?

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-12-4271-2015 ◽

2015 ◽

Vol 12 (4) ◽

pp. 4271-4314 ◽

Cited By ~ 5

Author(s):

S. Biskop ◽

F. Maussion ◽

P. Krause ◽

M. Fink

Keyword(s):

Tibetan Plateau ◽

Water Balance ◽

Hydrological Modeling ◽

Integrated Approach ◽

Water Levels ◽

The Tibetan Plateau ◽

Nam Co ◽

Water Balance Components ◽

South Central ◽

Lake Basins

Abstract. Lake-level fluctuations in closed basins on the Tibetan Plateau (TP) indicate climate-induced changes in the regional water balance. However, little is known about the region's key hydrological parameters, hampering the interpretation of these changes. The purpose of this study is to contribute to a more quantitative understanding of these controls. Four lakes in the south-central part of the TP were selected to analyze the spatiotemporal variations of water-balance components: Nam Co and Tangra Yumco (indicating increasing water levels), and Mapam Yumco and Paiku Co (indicating stable or slightly decreasing water levels). We present the results of an integrated approach combining hydrological modeling, atmospheric-model output and remote-sensing data. The hydrological model J2000g was adapted and extended according to the specific characteristics of closed lake basins on the TP and driven with "High Asia Refined analysis (HAR)" data at 10 km resolution for the period 2001–2010. Our results reveal that because of the small portion of glacier areas (1 to 7% of the total basin area) the contribution of glacier melt water accounts for only 14–30% of total runoff during the study period. Precipitation is found to be the principal factor controlling the water-balance in the four studied basins. The positive water balance in the Nam Co and Tangra Yumco basins was primarily related to larger precipitation amounts and thus higher runoff rates in comparison with the Paiku Co and Mapam Yumco basins. This study highlights the benefits of combining atmospheric and hydrological modeling. The presented approach can be readily transferred to other ungauged lake basins on the TP, opening new directions of research. Future work should go towards increasing the atmospheric model's spatial resolution and a better assessment of the model-chain uncertainties, especially in this region where observational data is missing.

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Potential forcing mechanisms of Holocene lake-level changes at Nam Co, Tibetan Plateau: Inferred from the stable isotopic composition of shells of the gastropod Radix

The Holocene ◽

10.1177/0959683616670247 ◽

2016 ◽

Vol 27 (4) ◽

pp. 594-604 ◽

Cited By ~ 6

Author(s):

Feng Chen ◽

Jin-Liang Feng ◽

Hai-Ping Hu ◽

Ji-Feng Zhang ◽

Shao-Peng Gao ◽

...

Keyword(s):

Tibetan Plateau ◽

Lake Level ◽

Late Holocene ◽

Causal Mechanism ◽

The Tibetan Plateau ◽

The South ◽

Large Area ◽

Nam Co ◽

Lake Level Changes ◽

South Central

The timing of lake-level fluctuations on the Tibetan Plateau and their relationship with climatic changes is still under debate, and the main reason for this is the lack of suitable archives for reconstructing the paleohydrology and paleoclimatology of the lakes. Here, we present the results of analyses of the shell geochemistry of Radix sp. from an exposed terrace of Nam Co lake on the south-central Tibetan Plateau. Optically stimulated luminescence (OSL) dating reveals that deep-water lacustrine sediments formed between ca. 4.4 and 2.2 ka, suggesting a high and stable lake level significantly above the present. The results of Sr/Ca, δ13C and δ18O analyses of the fossil shells of Radix sp. indicate that during the mid- to late-Holocene, lake-level variations in Nam Co were mainly controlled by variations in the Indian Summer Monsoon. A trend of decreasing evaporation also played an important role. Comparison with other results suggests a consistent pattern of mid- to late-Holocene lake-level changes across a large area of the Tibetan Plateau and adjacent regions to the south, which had a similar causal mechanism. Finally, our results indicate that fossil shells of the gastropod Radix sp. of the lakes on the Tibetan Plateau are a valuable archive for reconstructing the regional paleohydrology and paleoclimatology.

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Past the climate optimum: Recruitment is declining at the world’s highest juniper shrublines on the Tibetan Plateau

10.5194/egusphere-egu2020-3830 ◽

2020 ◽

Author(s):

Eryuan Liang ◽

Xiaoming Lu ◽

Yafeng Wang ◽

Flurin Babst ◽

Steven W. Leavitt ◽

...

Keyword(s):

Climate Change ◽

Tibetan Plateau ◽

The Tibetan Plateau ◽

Field Surveys ◽

Climate Conditions ◽

South Central ◽

Subsequent Decrease ◽

Central Tibetan Plateau ◽

The World ◽

Negative Impacts

<p>Alpine biomes are climate change hotspots, and treeline dynamics in particular have received much attention as visible evidence of climate-induced shifts in species distributions. Comparatively little is known, however, about the effects of climate change on alpine shrubline dynamics. Here, we reconstruct decadally resolved shrub recruitment history (age structure) through the combination of field surveys and dendroecology methods at the world&#8217;s highest juniper (Juniperus pingii var. wilsonii) shrublines on the south-central Tibetan Plateau. A total of 1,899 shrubs were surveyed at 12 plots located in four regions along an east-to-west declining precipitation gradient. We detected synchronous recruitment with 9 out of 12 plots showing a gradual increase from 1600 to 1900, a peak at 1900&#8211;1940, and a subsequent decrease from the 1930s onward. Shrub recruitment was significantly and positively correlated with reconstructed summer temperature from 1600 to 1940, whereas it was negatively associated with temperature in recent decades (1930&#8211;2000). Recruitment was also positively correlated with precipitation, except in the 1780&#8211;1830 period, when a trend toward wetter climate conditions began. This apparent tipping point in recruitment success coincides with a switch from positive to negative impacts of rising temperatures. &#160;Warming-induced drought limitation has likely reduced the recruitment potential of alpine juniper shrubs in recent decades. Continued warming is thus expected to further alter the dynamics of alpine shrublines on the Tibetan Plateau and elsewhere.</p>

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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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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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Horizontal hydraulic conductivity of shallow streambed sediments and comparison with the grain-size analysis results

Hydrological Processes ◽

10.1002/hyp.8143 ◽

2011 ◽

Vol 26 (3) ◽

pp. 454-466 ◽

Cited By ~ 36

Author(s):

Chengpeng Lu ◽

Xunhong Chen ◽

Cheng Cheng ◽

Gengxin Ou ◽

Longcang Shu

Keyword(s):

Grain Size ◽

Hydraulic Conductivity ◽

Grain Size Analysis ◽

Size Analysis ◽

Streambed Sediments

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Origin and formation model of Eocene dolomite in the upper Niubao Formation of Lunpola Basin, Tibetan Plateau

Interpretation ◽

10.1190/int-2020-0195.1 ◽

2021 ◽

pp. 1-50

Author(s):

Xiaoquan Chen ◽

Fengcun Xing ◽

Shu Jiang ◽

Yongchao Lu ◽

Zhongrong Liu ◽

...

Keyword(s):

Tibetan Plateau ◽

Hot Springs ◽

Northern China ◽

Hydrothermal Fluids ◽

Lake Basin ◽

The Tibetan Plateau ◽

Climate Conditions ◽

Hot Climate ◽

Strong Evaporation ◽

Semi Arid

Using fresh cores samples, we determined the origin and formation process of Eocene lacustrine dolomites in the Tibetan Plateau through petrological, mineralogical, and geochemical analyses. Dolomitic rocks were collected from the upper member of Eocene Niubao Formation in the Lunpola Basin, and consist of dolomitic mudstone, argillaceous dolomite, dolomite-bearing mudstone and mud-bearing dolomite. These dolomites are dominated by aphanotopic and micro-crystalline dolomites, with minor amounts of euhedral or subhedral powder- and fine-crystalline dolomites. Carbon and oxygen stable isotopes, combined with ubiquitous gypsum in study area, indicates a semi-saline continental lake under strong evaporative conditions. The revealed relatively high temperature of dolomitization(33.8°C–119.1°C), combined with hydrothermal minerals such as cerous phosphate and barite, reflect the participation of dolomite from hot fluids. Moreover, the inferred dolomitization temperatures decrease gradually toward the centre of the lake basin, suggesting the resurgence of hydrothermal fluids along a fault zone on the lake margin. This proves that frequent thermal events occurred at the boundary fault of the Lunpola Basin margin during early Himalayan orogenesis. In addition, Jurassic carbonates interacting with hydrothermal fluids, as well as strong evaporation conditions, likely provided favourable conditions for the formation of primary lime sediments. A rich source of Mg2+ brought by volcanic ash, hydrothermal fluids, and the Jurassic carbonates then created conditions for dolomitization during the depositional period. Strong evaporation under a relatively hot climate enhanced penecontemporaneous dolomitization, thus forming dolomite. Tibetan Plateau was under arid to semi-arid climate conditions, and there was a widespread distribution of dolostones in western, central, and northern China during the Eocene period. The hydrothermal dolomites of the upper Niubao Formation testify for active hot springs, while lacustrine dolomite imply arid or semi-arid climates during the Eocene, in the early stages of Himalayan orogenesis.

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

10.5194/acp-2016-989 ◽

2016 ◽

Author(s):

Jiao Ren ◽

Xiaoping Wang ◽

Chuanfei Wang ◽

Ping Gong ◽

Tandong Yao

Keyword(s):

Tibetan Plateau ◽

Organic Pollutants ◽

Persistent Organic Pollutants ◽

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 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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