Major and trace elements as well as strontium isotopic composition have been analyzed on the acid-insoluble (AI) phase of the loess-paleosol sequence from Luochuan, Shaanxi Province, China. Results show that the chemi...Major and trace elements as well as strontium isotopic composition have been analyzed on the acid-insoluble (AI) phase of the loess-paleosol sequence from Luochuan, Shaanxi Province, China. Results show that the chemical composition of AI phase of loess and paleosols is distinctive to the average composition of upper continental crust (UCC), characterized by depletion of mobile elements Na, Ca and Sr. The distribution pattern of elements in AI phase reveals that initial dust, derived from a vast area of Asian inland, has suffered from Na- and Ca-removed chemical weathering compared to UCC. Some geochemical parameters (such as CIA values, Na/K, Rb/Sr and87Sr/86Sr ratios) display a regular variation and evolution, reflecting that the chemical weathering in the source region of loess deposits has decreased gradually since 2.5 Ma with the general increase of global ice volume. This coincidence reflects that the aridity of Asian inland since the Quaternary is a possible regional response to the global climate change.展开更多
Eolian flux in the Chinese Loess Plateau was reconstructed by measuring the dry bulk density and CaCO3 content of the late Cenozoic loess-paleosol-red clay sequences in the Lingtai profile. Comparison of eolian flux v...Eolian flux in the Chinese Loess Plateau was reconstructed by measuring the dry bulk density and CaCO3 content of the late Cenozoic loess-paleosol-red clay sequences in the Lingtai profile. Comparison of eolian flux variation between the Lingtai profile and the ODP sites 885/886 in the North Pacific shows a significant wet-dry variability in addition to a gradual drying trend in the dust source regions in interior Asia. Especially, the increase of eolian fluxes from both continental and pelagic eolian sediments indicates a sharp drying of the dust source regions between 3.6 and 2.6 MaBP, which might be attributed to the tectonic uplift of the Tibetan Plateau, which cut down the moisture input to the interior Asia. The average value and variability of eolian flux are higher after 2.6 MaBP than before, which may be related to the Quaternary climatic fluctuations on the glacial-interglacial timescale after the commencement of major Northern Hemisphere Glaciations. The eolian fluxes of the Lingtai profile and Core V21-146 in northwest Pacific show a synchronous variation on the 103-105 a timescale, indicating that the flux variations from both continental and marine records are closely correlated to the Quaternary climatic fluctuation forced by the ice volume changes on a global scale.展开更多
Based on the data up to 1999 from hydroclimatological departments, this pape analyzes the climatic divide implications of the Qinling Mountains in regional response to the process of climate warming, due to which the ...Based on the data up to 1999 from hydroclimatological departments, this pape analyzes the climatic divide implications of the Qinling Mountains in regional response to the process of climate warming, due to which the grades of dryness/wetness (GDW) in 100 years show that the northern region has entered a drought period, while the southern is a humid period. In a course of ten years, the D-value of annual average air temperature over southern Shaanxi (the Hanjiang Valley) and the Central Shaanxi Plain (the Guanzhong Plain) has narrowed, i.e., the former with a slight change and the latter with rapid increase in temperature. Both regions were arid with the decrease in precipition D-value, namely the plain became warmer while the south was drier. The Qinling Mountains play a pronounced role in the climatic divide. The runoff coefficient (RC) of the Weihe River decreases synchronously with that of the Hanjiang due to climate warming. The RC of Weihe dropped from 0.2 in the 1950s to less than 0.1 in the 1990s. The Weihe Valley (the Guanzhong Plain) is practically an arid area due to shortage of water. The successive 0.5, 1.0°C temperature anomaly over China marks, perhaps, the improtant transition period in which the environment becomes more vulnerable than before. The study shows the obvious trend of environmental aridity, which is of help to the understanding of regional response to global climate change.展开更多
Recently,a hot topic about warmer and wetter climate change in the arid region of Northwest China,especially in Xinjiang,has attracted much attention by general public and scientific community.This study revisits this...Recently,a hot topic about warmer and wetter climate change in the arid region of Northwest China,especially in Xinjiang,has attracted much attention by general public and scientific community.This study revisits this topic especially for Xinjiang in the Eurasian continental context from multiple perspectives based on most updated CRU high-resolution grid data and China's homogenized station data in 1961–2019.We conclude that such‘warming-wetting’trend is not a regional phenomenon for Xinjiang but has much larger spatial scale.Regions having experienced both temperature and precipitation increases reflecting‘warming-wetting’trend account for more than half of the Eurasian continent since 1961.Nevertheless,the‘warming-wetting’trend in Xinjiang suggests some unique regional features in response to the global warming.Although drought seems to have relieved to some extent,especially in the mountainous regions in western Xinjiang,the nature of arid and semi-arid climate regime has not changed.Noticeably,the interannual variability of precipitation has enlarged and the increase in extreme precipitation events has a major contribution.These findings suggest that‘warming-wetting’trend in Xinjiang is asymmetric regarding warming and wetting in seasons and intensifying interannual variability and increasing contribution of extreme precipitation to the total.Thus,the current‘warming-wetting’trend in Xinjiang possibly brings us some beneficial impacts for the ecosystem but also increases challenges for water resources utilization and risk management.展开更多
基金The authors are grateful to Dr. Lu Huayu from the State Key Laboratory of Loess and QuaternaryGeology for his assistance in field work. This work was supported by NKBRSF (G1999043400), National Natural Science Foundation of China (Grant No. 49725307) a
文摘Major and trace elements as well as strontium isotopic composition have been analyzed on the acid-insoluble (AI) phase of the loess-paleosol sequence from Luochuan, Shaanxi Province, China. Results show that the chemical composition of AI phase of loess and paleosols is distinctive to the average composition of upper continental crust (UCC), characterized by depletion of mobile elements Na, Ca and Sr. The distribution pattern of elements in AI phase reveals that initial dust, derived from a vast area of Asian inland, has suffered from Na- and Ca-removed chemical weathering compared to UCC. Some geochemical parameters (such as CIA values, Na/K, Rb/Sr and87Sr/86Sr ratios) display a regular variation and evolution, reflecting that the chemical weathering in the source region of loess deposits has decreased gradually since 2.5 Ma with the general increase of global ice volume. This coincidence reflects that the aridity of Asian inland since the Quaternary is a possible regional response to the global climate change.
基金This work was supported by the Key Project of Knowledge Innovation of the CAS (Grant Nos. KZCXl-10-01 and KZCX2-108) the National Natural Science Foundation of China (Grant Nos. 40106006 and 90102017) the National Key Basic Research Development
文摘Eolian flux in the Chinese Loess Plateau was reconstructed by measuring the dry bulk density and CaCO3 content of the late Cenozoic loess-paleosol-red clay sequences in the Lingtai profile. Comparison of eolian flux variation between the Lingtai profile and the ODP sites 885/886 in the North Pacific shows a significant wet-dry variability in addition to a gradual drying trend in the dust source regions in interior Asia. Especially, the increase of eolian fluxes from both continental and pelagic eolian sediments indicates a sharp drying of the dust source regions between 3.6 and 2.6 MaBP, which might be attributed to the tectonic uplift of the Tibetan Plateau, which cut down the moisture input to the interior Asia. The average value and variability of eolian flux are higher after 2.6 MaBP than before, which may be related to the Quaternary climatic fluctuations on the glacial-interglacial timescale after the commencement of major Northern Hemisphere Glaciations. The eolian fluxes of the Lingtai profile and Core V21-146 in northwest Pacific show a synchronous variation on the 103-105 a timescale, indicating that the flux variations from both continental and marine records are closely correlated to the Quaternary climatic fluctuation forced by the ice volume changes on a global scale.
基金Knowledge Innovation Project of Chinese Academy of Sciences, KZCX2-310-05 National Natural Science Foundation of China, No.4007
文摘Based on the data up to 1999 from hydroclimatological departments, this pape analyzes the climatic divide implications of the Qinling Mountains in regional response to the process of climate warming, due to which the grades of dryness/wetness (GDW) in 100 years show that the northern region has entered a drought period, while the southern is a humid period. In a course of ten years, the D-value of annual average air temperature over southern Shaanxi (the Hanjiang Valley) and the Central Shaanxi Plain (the Guanzhong Plain) has narrowed, i.e., the former with a slight change and the latter with rapid increase in temperature. Both regions were arid with the decrease in precipition D-value, namely the plain became warmer while the south was drier. The Qinling Mountains play a pronounced role in the climatic divide. The runoff coefficient (RC) of the Weihe River decreases synchronously with that of the Hanjiang due to climate warming. The RC of Weihe dropped from 0.2 in the 1950s to less than 0.1 in the 1990s. The Weihe Valley (the Guanzhong Plain) is practically an arid area due to shortage of water. The successive 0.5, 1.0°C temperature anomaly over China marks, perhaps, the improtant transition period in which the environment becomes more vulnerable than before. The study shows the obvious trend of environmental aridity, which is of help to the understanding of regional response to global climate change.
基金supported by the National Key Research and Development Program of China(2018YFC1507700).
文摘Recently,a hot topic about warmer and wetter climate change in the arid region of Northwest China,especially in Xinjiang,has attracted much attention by general public and scientific community.This study revisits this topic especially for Xinjiang in the Eurasian continental context from multiple perspectives based on most updated CRU high-resolution grid data and China's homogenized station data in 1961–2019.We conclude that such‘warming-wetting’trend is not a regional phenomenon for Xinjiang but has much larger spatial scale.Regions having experienced both temperature and precipitation increases reflecting‘warming-wetting’trend account for more than half of the Eurasian continent since 1961.Nevertheless,the‘warming-wetting’trend in Xinjiang suggests some unique regional features in response to the global warming.Although drought seems to have relieved to some extent,especially in the mountainous regions in western Xinjiang,the nature of arid and semi-arid climate regime has not changed.Noticeably,the interannual variability of precipitation has enlarged and the increase in extreme precipitation events has a major contribution.These findings suggest that‘warming-wetting’trend in Xinjiang is asymmetric regarding warming and wetting in seasons and intensifying interannual variability and increasing contribution of extreme precipitation to the total.Thus,the current‘warming-wetting’trend in Xinjiang possibly brings us some beneficial impacts for the ecosystem but also increases challenges for water resources utilization and risk management.
