| 1. |
- Sun, He, et al.
(author)
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Contrasting precipitation gradient characteristics between westerlies and monsoon dominated upstream river basins in the Third Pole
- 2020
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In: Kexue Tongbao/Chinese Science Bulletin. - 0023-074X .- 2095-9419. ; 65, s. 91-104
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Journal article (peer-reviewed)abstract
- © 2020, Science Press. All right reserved. Based on precipitation observations from 256 gauges in the westerly and monsoon dominated upstream river basins of the Third Pole (TP), this study determined the relationships between precipitation and elevation. The basins include the upper basins of the Yangtze, Yellow, Lancang, Nujiang, Yarlung Zangbo, Yarkant, Indus, Amu Darya, and Syr Darya. Using the ERA5 data, this work examined the possible reasons for the difference in the characteristics of precipitation gradient, i.e. analyzing the relationships between the total column water vapor (TCWV), convective available potential energy (CAPE), lifting condensation level (LCL) and elevation, respectively. The feasibility of orographic corrections of precipitation data or observation is validated with the improved VIC land surface hydrological model in two mountain basins in the TP. Mean annual precipitation from gauges generally show decreasing trends (17-128 mm/100 m) with increased elevation (2500-5500 m a.s.l.) in the monsoon dominated basins, i.e. upper Yangtze, Yellow, Lancang, Nujiang, and Yarlung Zangbo, while the orographic enhancements are observed at relatively smaller scales, such as, in the very source regions of the upper Lancang and Nujiang, and Rikaze sub-basin with areas of 11000-67740 km2. On the other hand, in the westerly dominated basins, mean annual precipitation tends to increase with elevation (5-64 mm/100 m) in the upper Yarkant, Indus, Amu Darya, and Syr Darya. The precipitation estimates from ERA5 show a good correspondence with the gauge data (R=0.6-0.9, P<0.05), and exhibit a general consistent precipitation gradient pattern with the gauge observations. The ERA5 variables of TCWV, CAPE, and LCL are useful to understand the factors for the spatial pattern of precipitation vertical gradients in the TP basins with different climate control. The TCWV, CAPE, and LCL represent the vertically integrated moisture, instability and condensation necessary for the generation and development of precipitation. The larger TCWV, higher CAPE and lower LCL enhance precipitation. The decrease of precipitation with elevation in monsoon basins is caused by the decrease of TCWV with elevation, while the increase of precipitation with elevation in westerly dominated basins is a result of increasing CAPE and decreasing LCL with elevation. Hydrological modeling results in the upper Yarkant basin and Rikaze basin indicate that the orographic correction of precipitation data significantly improves the model accuracy, reducing the biases to less than 5% relative to flow observations. This work demonstrates that precipitation correction through vertical gradients is an effective way to derive high mountainous precipitation estimates for hydrological modeling from lowland gauges in the TP, especially in the westerly dominated basins, and in monsoon basins at regional or local scales. Knowledge of the spatial and temporal characters and variations of precipitation over the TP is greatly incomplete, which largely hampers the understanding on climate variability and water availability projections in the TP. This study offers a useful reference to derive reliable mountain precipitation through orographic correction, and also provides a scientific basis to establish precipitation observation network in the Second Tibetan Plateau Scientific Expedition and Research.
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| 2. |
- Tang, Q. H., et al.
(author)
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Streamflow change on the Qinghai-Tibet Plateau and its impacts
- 2019
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In: Chinese Science Bulletin-Chinese. - : Science China Press., Co. Ltd.. - 0023-074X. ; 64:27, s. 2807-2821
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Journal article (peer-reviewed)abstract
- The Qinghai-Tibet Plateau (QTP), also often called the Third Pole, is considered the Asian Water Tower because it is the source of many major Asian rivers. The environmental change on the QTP can affect the climate system over the surrounding area, and the changes in glacier and river streamflow on the QTP will lead to cascading impacts in downstream area where billions of people live. This paper reviews the hydrological observations and streamflow changes of the major Asian rivers originating from the QTP. From the 1950s to the beginning of the 21st century, streamflow on the QTP overall shows large interannual variations but no significant trends. The monthly mean streamflows during the flooding seasons are the largest in the 1960s for the outlet stations on the QTP. Annual streamflow in the source region of the Yellow River decreased while that in the source region of the Yangtze River increased slightly. No significant trends of annual streamflow have been reported for the other river source regions. The mean streamflows during peak season are relatively large in the 2000s at the river source region (upper reaches) of most rivers on the QTP. An increasing trend of streamflow in spring has been found in the upper reaches of the Yellow River, the Lancang River, the Tuotuo River (of the Yangtze River), and the Lhasa River (of the Yarlung Zangbo River). The largest month of streamflow often appears in July for most stations, but in August at the Lhasa and Nuxia stations which are located in the Yarlung Zangbo River. Streamflow changes on the QTP could be mainly attributed to changes in snow and ice, as little influence from direct human activities were found. However, the examination of the streamflow changes largely relies on the hydrological observations. So far, due to data unavailability, we are still unclear about the long-term change in the streamflow on the QTP, especially the changes in recent years. The changes in ice and snow pack on the QTP could have significant impact on the downstream water resources and ecosystem. As more water resources have been generated from ice/snow melting, from a long-term perspective, water resources would be reduced along with shrinking and disappearing glaciers. Hydrological projections under future climate change suggest that streamflow in most river source regions would increase along with precipitation and increases in ice/snow melting, and hydrological extremes such as flooding would occur more frequently. Large uncertainties across Generic Circulation Models (GCMs) and hydrological models have been found in future projections of streamflow on the QTP. Reduction of ice/snow melting would aggravate the water stress conditions for both the ecosystem and human society on the QTP and its downstream areas. Sparse hydrometeorological observations in the past, particularly in the remote region of the QTP, are a major limiting factor to studies on streamflow change and its impacts. Further efforts are urgently needed to combine the advanced observation and modeling technologies to improve the observation and simulation capabilities of the water cycle over the QTP, and to provide scientific and technological support for coping with the accelerated ice/snow melting, increasing hydrological extremes and their impacts over the QTP.
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| 3. |
- Xi, Qiaojuan, et al.
(author)
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中国主要流域灰-绿-蓝蓄水能力时空演变 : [Spatio-temporal variation of gray-green-blue storage capacity in nine major basins of China]
- 2021
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In: Chinese Science Bulletin-Chinese. - 0023-074X .- 2095-9419. ; 66:34, s. 4437-4448
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Journal article (peer-reviewed)abstract
- Most of China's territory is influenced by the East Asia monsoon, and thus, the spatio-temporal distribution of surface water resources in China is extremely uneven, causing many water-related issues, e.g.. water scarcity and flooding. As the basis and essential condition of economic and social development, water-related infrastructures provide the material basis and guarantee for regulating and storing surface water resources and solving multi-dimensional water problems. The infrastructures that play an important role in surface water resource regulation and storage mainly include three types: Gray (such as dams), green (such as forests), and blue infrastructures (such as lakes). Gray infrastructures can reduce the flood peak and increase water supply during dry seasons by regulating and storing water so that the seasonal and inter-annual fluctuation of runoff is reduced, which plays an important role in water storage, water supply, flood control, and disaster mitigation. However, excessive gray infrastructures would have adverse effects on the social economy and environmental ecology. Unlike gray infrastructures, green and blue infrastructures can not only benefit water resource management but also have ecological functions, such as improving water quality and enhancing ecosystem services. Thus. it is significant to couple gray, green, and blue infrastructures to regulate the spatio-temporal distribution of water resources. However, research on the spatial distribution and temporal variation of water storage capacity is still lacking, which hinders the coordinated regulation and comprehensive management of surface water resources. Therefore, in the present study, the spatio-temporal distribution of the three aforementioned infrastructures was compared and analyzed on basin scale, based on the latest data of darns, root zone storage capacity, natural lakes, and so on. Results indicated the following: (1) Gray water storage capacity has exceeded that of the natural terrestrial surface ecosystem in the Yangtze River Basin and the Southeast Basins, where human activities are intense. (2) Gray water storage capacity has increased significantly in nine major basins from 1955 to 2020, but the timing of construction varies in different basins. (3) Green water storage capacity did not change much, the Songhua-Liaohe River Basin and the Huaihe River Basin increased slightly. (4) Blue water storage capacity shows a constantly increasing trend on the whole, in which the water storage capacity in the inland river basin (including the endorheic basin on the Tibetan Plateau) significantly increased. Our study revealed the basic information and spatio-temporal variation of gray-green-blue water storage capacities in nine major basins of China, which could lead to better coordination between natural and artificial water infrastructures and provide support for multidimensional optimization of water resource allocation.
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| 4. |
- Yang, Haijun, et al.
(author)
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多百年际气候变率 : 观测、理论与模拟研究 [Multi-centennial climate variability: Observational, theoretical and modeling studies]
- 2023
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In: Chinese Science Bulletin. - 0023-074X .- 2095-9419. ; 68:16, s. 2037-2045
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Journal article (peer-reviewed)abstract
- Research using long-term proxy data suggests the existence of multi-centennial climate variability in the Earth’s climate system. Its origin and mechanism have been bewildering for climatologists and archaeologists for a long time. Considering that the variation of external forcing of the Earth’ climate was relatively small from the mid-Holocene to the pre-industrial time, it is important to investigate the role of internal natural oscillation of the climate system during this period. The Atlantic meridional overturning circulation (AMOC) is thought to be the first candidate for such multi-centennial timescale variability. It is thus critical to investigate systematically the connection between the AMOC and the Earth climate system at this timescale. From the mid-Holocene to the pre-industrial time, the human civilization experienced rapid development. Historical documents in China suggest that in the past 2000 years, the historical climate in China had a low-frequency variation with 200–300 year period, which might have affected the ancient Chinese civilization. The multi-centennial variability of the AMOC may have played a role in the vax and vane of the human civilization.Currently, there is a lack of in-depth studies on the multi-centennial variability of the AMOC. This is mainly due to the following factors. First, the time period of modern instrumental observations is less than 200 years, which is not long enough to confirm the existence of the multi-centennial climate variability. Second, there is a lack of a well-recognized theory that can account for the multi-centennial variability of the AMOC. Third, it is much easier for a researcher to study the Earth climate change due to external forcing than to study the internal variability of the Earth climate system under a stable external forcing, particularly at this long timescale.Several coupled Earth climate system models have simulated the multi-centennial variability of the AMOC. However, the results from both coupled models and proxy data include comprehensive factors. To fundamentally understand the multi-centennial climate variability, a simple theoretical model is needed. Unfortunately, there is a lack of theoretical studies on the internal multi-centennial variability under the background of stable climate.In this work, we systematically review the current studies on multi-centennial climate variability from observational, theoretical and coupled modeling aspects. We hope that by proposing innovative theory and creative climate modeling approach, we can identify the intrinsic mode of multi-centennial climate variability, picture its spatial pattern, decipher the origin of its timescale, and reveal its internal mechanism. The outcome of these studies will help us understand deeply the wax and wane of the human civilization during the past several thousand years. It will also be of great significance for a better prediction of the long-term trend of future climate change.
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| 5. |
- Yang, Zhongwei, et al.
(author)
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Application of bismuth sulfide based nanomaterials in cancer diagnosis and treatment
- 2023
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In: Kexue Tongbao/Chinese Science Bulletin. - 0023-074X .- 2095-9419. ; 68:16, s. 2101-2115
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Journal article (peer-reviewed)abstract
- Cancer is a complicated disease with a significant degree of heterogeneity, despite having made impressive advances in the field of cancer treatment, cancer remains a major threat to human life and health. The complexity of cancer on the genetic and phenotypic planes defines its clinical diversity and the difficulty of treatment. The increasing incidence of integrative types as well as individual types of cancer with the passage of time has prompted the development of novel cancer treatment strategies. Current treatment protocols are based on correcting gene mis-expression, blocking nutrient delivery to the tumor, or destroying the cancer cells. Often, surgery cannot completely eliminate all cancer cells in the body, leaving the cancer at risk of recurrence and high mortality. Chemotherapy and radiotherapy have serious side effects on normal tissue cells in the body while killing cancer cells, and these approaches are still unsatisfactory due to insufficient specificity and dose limitations. The development of novel drugs with specific targeted therapies or site-specific delivery systems to deliver therapeutic agents can greatly avoid the toxicity to healthy tissues caused by non-specificity. The preparation of nanomaterials is the most important basic technology in nanotechnology research, as well as a prerequisite for nanoapplication technology and nano-industrialization, which has been the key focus of nanotechnology researchers’ attention and research. With the development of nanotechnology, multifunctional nanomaterials, which integrate various diagnostic and therapeutic functions, have become the most active field in nanoscale research, and have been applied in the fields of early screening of tumors, identification of tumor biomarkers, targeted release of chemotherapeutic drugs and development of novel therapies. After decades of development, biomedical nanomaterials have been applied to cancer diagnosis, tumor imaging, drug loading, tumor therapy, etc. They have excellent biocompatibility and biodistribution, with advantages unmatched over traditional therapeutic methods. Among them, Bi2S3 based nanomaterials have attracted great attention in the biomedical field due to their special photothermal effect and biocompatibility, etc. The authors summarize the preparation methods of Bi2S3 based nanomaterials with different morphological dimensions reported in the literature, as well as effective strategies for constructing different heterogeneous structures. Currently, Bi2S3 based nanomaterials have been widely used in cancer diagnosis. The main strategy is the combination of various functionalized probe-loaded Bi2S3 with various imaging methods to determine tumor boundaries, histological analysis and 3D stereoscopic imaging detection. Meanwhile, due to its superior photothermal conversion efficiency and X-ray attenuation coefficient, Bi2S3 based nanomaterials have been widely used in a range of fields such as photothermal therapy, photodynamic therapy, radio sensitization therapy, immunotherapy and chemotherapy by means of rational modifications and loading. Since individual imaging modalities cannot provide complete information about the tumor treatment, Bi2S3 based nanomaterials with multimodal imaging capabilities can enable real-time monitoring of tumors and real-time observation of therapeutic agent metabolism, providing guidance for tumor treatment. In addition, a mono-therapeutic approach is often unable to completely inhibit and kill tumors, so Bi2S3 based nanomaterials integrating multiple therapeutic approaches can not only reduce the dose of chemotherapeutic drugs, but also cause serious damage to tumor cells and inhibit the metastasis of cancer cells, which greatly reduces the possibility of tumor recurrence and is of great significance for a favorable prognosis of tumor treatment. Finally, the authors highlight and discuss the biosafety and biodistribution of Bi2S3 based nanomaterials, as well as summarize methods to improve the biocompatibility of nanoparticles, providing indicative clues for further biosafety applications of Bi2S3 based nanomaterials.
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