Using the observed data from 184 stations over the Yunnan-Guizhou Plateau （YGP） from 1961 to 2005, the long-term trends in sunshine duration, cloud amount, dry visibility （Vd）, dry extinction, and water vapor over...Using the observed data from 184 stations over the Yunnan-Guizhou Plateau （YGP） from 1961 to 2005, the long-term trends in sunshine duration, cloud amount, dry visibility （Vd）, dry extinction, and water vapor over the YGP are analyzed. The results show that 85% of the stations recorded shortening annual sunshine duration, with the decrease rates between -12.2 and -173.7 h/10yr. Results of Mann-Kendall tests indicate that, among the stations with decreasing sunshine duration, 63.7% of them experienced an abrupt change that started in the 1970s and peaked in the 1980s. This decreasing trend has reversed in the early years of the 21st century. The cloud cover and water vapor content in the mid and lower levels over the YGP had no obvious changes during the study period. The annual averages of Vd declined from 34 km in the 1960s to 27 km at present. The annual mean dry extinction coefficient trended upward, from 0.176 to 0.190, on the YGP from 1980 to 2005. Analyses of cloud cover, water vapor, atmospheric visibility, and dry extinction coefficient revealed that emitted tropospheric aerosols （including air pollutants） resulting from increased energy consumption over the YGP could be a major Factor influencing the reductions of sunshine duration and atmospheric visibility.展开更多
The origin, development and expansion of prehistoric agriculture in East Asia have been widely investigated over the past two decades using archaeobotanical analysis from excavated Neolithic and Bronze Age sites. Rese...The origin, development and expansion of prehistoric agriculture in East Asia have been widely investigated over the past two decades using archaeobotanical analysis from excavated Neolithic and Bronze Age sites. Research on prehistoric agriculture has predominantly focused in the valleys of the Yellow River and the Yangtze River. Agricultural development during the Neolithic and Bronze Age periods in the Yunnan-Guizhou Plateau of southwest China, an important passageway for human migration into Southeast Asia, still remains unclear. In this paper, based on macrofossil and microfossil analysis and radiocarbon dating at the Shilinggang site, we investigate plant subsistence strategies in the Nujiang River valley during the Bronze Age period. Combined with previous archaeobotanical studies in the Yunnan-Guizhou Plateau, we explore agricultural development processes in this area during the Neolithic and Bronze Age. Our results indicate that rice and foxtail millet were cultivated in Shilinggang around 2500 cal a BP. Three phases of prehistoric agricultural development in the Yunnan-Guizhou Plateau can be identified: rice cultivation from 4800–3900 cal a BP, mixed rice and millet crop(foxtail millet and broomcorn millet) cultivation from 3900–3400 cal a BP, and mixed rice, millet crop and wheat cultivation from 3400–2300 cal a BP. The development of agriculture in the Yunnan-Guizhou Plateau during the Neolithic and Bronze Age periods was primarily promoted by prehistoric agriculture expansion across Eurasia, agricultural expansion which was also affected by the topographic and hydrological characteristics of the area.展开更多
Landscape evolution is modulated by the regional tectonic uplift,climate change,and river dynamics.However,how to distinguish these mechanisms through the research of surface exhumation and fluvial incision remains co...Landscape evolution is modulated by the regional tectonic uplift,climate change,and river dynamics.However,how to distinguish these mechanisms through the research of surface exhumation and fluvial incision remains controversial.In this study,cosmogenic ^(10)Be,^(26)Al,and ^(21)Ne concentrations in quartz from cave deposits,modern river sediments,and bedrocks were measured to constrain the applicability of cosmogenic ^(21)Ne and discuss Quaternary landscape evolution history in the Guizhou Plateau,southeast China.Using the ^(26)Al-^(10)Be and ^(21)Ne-^(10)Be pairs to distinguish the cosmogenic ^(21)Ne concentration from the excess ^(21)Ne,we found that the nucleogenic ^(21)Ne produced by the U and Th decay in quartz is significant in the samples although there is the possibility of inherited cosmogenic ^(21)Ne.Combining with previous studies,we suggest that the precise approach for applying the cosmogenic ^(21)Ne could be reached by(1)estimating the contribution from nucleogenic ^(21)Ne,(2)avoiding samples with complex burial histories to exclude inherited cosmogenic ^(21)Ne,and(3)combining the ^(10)Be-^(26)Al-^(21)Ne nuclides method for the Quaternary samples.In addition,both pre-burial basin denudation rates and burial ages derived from the ^(26)Al-^(10)Be pair were used to determine the different timescale surface denudation rate and fluvial incision rate in relation to previous work.The consistency of the different timescales pre-burial basin denudation rate,^(36)Cl surface denudation rate,and modern basin denudation rate indicates that the landscape-scale surface denudation has been likely stabilized since the Quaternary in the Guizhou Plateau area.The slightly higher river incision rates than the local surface denudation rate show that the river dynamics may not have reached a steady-state due to the regional tectonic uplift in the Guizhou Plateau.展开更多
Analysis of a heavy rainfall in a lower latitude plateau and characteristics of water vapor transportation have been conducted by using conventional data and denser surface data. The results show： （1） the heavy rai...Analysis of a heavy rainfall in a lower latitude plateau and characteristics of water vapor transportation have been conducted by using conventional data and denser surface data. The results show： （1） the heavy rainfall was caused by a series of mesoscale systems under favorable large-scale conditions when the warm moister air and cold air interacted with each other. At the same time, the coupling between the upper- and lower-level jets was revealed. It is also found that there exists some different characteristics among the main influencing systems of heavy rainfalls in Yunnan, such as the Indian-Myanmar trough and the path of the cold air, compared with those in East and South China. （2） The interaction between mesoscale convergence lines near the ground may be a possible triggering mechanism for the occurrence of mesoscale systems, and the dynamical and thermal dynamical structure of the mesoscale systems was very obvious. The convergence lines may relate closely to the terrain of Yunnan, China. （3） The computation of the water vapor budget reveals that the primary source of water vapor supply for heavy rainfall was in the Bay of Bengal. In this case, the water vapor could be transported into Yunnan even though the amount of water vapor was less than that in the lower troposphere in East and South China. In addition, the analysis for three-dimensional air parcel trajectories better revealed and described the source location and the transportation of water vapor to Yunnan.展开更多
It is necessary to understand the aquatic chemical characteristics of natural surfacefresh water for water quality assessment. The chemical data from different kinds of water inthe central Guizhou karst area showed th...It is necessary to understand the aquatic chemical characteristics of natural surfacefresh water for water quality assessment. The chemical data from different kinds of water inthe central Guizhou karst area showed that spring water from carbonate rock cracks (crack-water) is of neutrality or meta-alkalinity and [C] Ca Ⅱ type. The amounts of all ions and theconcentrations of HCO3 and Ca2+ were higher in the autumn than in the spring. the crack-water was influenced by the infiltration of surface water in the process of erosion and/or transportation with decreasing HCO3- and increasing PH, SO, Cl, K+ and Na+ during runningin a certain distance on the land suffice. In particular, the chemical compeitions of the watersat Tianxingqiao (upper-stream), Shuiliandong (mid-waterfall) and Luoshuitan (down-pool)near the Huangguoshu Waterfall were much different from those of the crack-water. The concentrations of , Na+, Fe3+ and NO3- varied closely with seasons. The CaCO3 depositedviolently with CO2 release in the spring. In Lake Hongfeng the HCO3- /So- equivalent ratioswere only 2. 1 - 2. 4, but Ca2 + /Md+ up tO 2. 4 - 4. 2. The CI- concentration increased by afactor Of 1 and Na+ by order of magnitude relative to the spring water. These indicated the in-crease in artificial pollutant discharge in the Lake Hongfeng watershed. In addition, porewater in the soils coveing carbonate rocks belongs to strongly mineralized water. The obvious differences in water quality were controlled by carbonate despition, sulphate mineralization and nitrogen fixation as well as ammonification. It is indicated that the chemical compeitions in thewaters from the karst region were unstable and changeable.展开更多
基金funded by the National Natural Science Foundation of China (NSFC) (Grant No. 40965009)the Guizhou Provincial Meteorological Bureau Key Laboratory Programme (No. KF200906)
文摘Using the observed data from 184 stations over the Yunnan-Guizhou Plateau （YGP） from 1961 to 2005, the long-term trends in sunshine duration, cloud amount, dry visibility （Vd）, dry extinction, and water vapor over the YGP are analyzed. The results show that 85% of the stations recorded shortening annual sunshine duration, with the decrease rates between -12.2 and -173.7 h/10yr. Results of Mann-Kendall tests indicate that, among the stations with decreasing sunshine duration, 63.7% of them experienced an abrupt change that started in the 1970s and peaked in the 1980s. This decreasing trend has reversed in the early years of the 21st century. The cloud cover and water vapor content in the mid and lower levels over the YGP had no obvious changes during the study period. The annual averages of Vd declined from 34 km in the 1960s to 27 km at present. The annual mean dry extinction coefficient trended upward, from 0.176 to 0.190, on the YGP from 1980 to 2005. Analyses of cloud cover, water vapor, atmospheric visibility, and dry extinction coefficient revealed that emitted tropospheric aerosols （including air pollutants） resulting from increased energy consumption over the YGP could be a major Factor influencing the reductions of sunshine duration and atmospheric visibility.
基金supported by the National Natural Science Foundation of China (Grant No. 41271218)the Project Strategic Priority Research Program-Climate Change: Carbon Budget and Relevant Issuse of the Chinese Academy of Sciences (Grant No. XDA05130601)the Fundamental Research Funds for the Central Universities (Grant Nos. LZUJBKY-2015-k09 and LZUJBKY-2014-116)
文摘The origin, development and expansion of prehistoric agriculture in East Asia have been widely investigated over the past two decades using archaeobotanical analysis from excavated Neolithic and Bronze Age sites. Research on prehistoric agriculture has predominantly focused in the valleys of the Yellow River and the Yangtze River. Agricultural development during the Neolithic and Bronze Age periods in the Yunnan-Guizhou Plateau of southwest China, an important passageway for human migration into Southeast Asia, still remains unclear. In this paper, based on macrofossil and microfossil analysis and radiocarbon dating at the Shilinggang site, we investigate plant subsistence strategies in the Nujiang River valley during the Bronze Age period. Combined with previous archaeobotanical studies in the Yunnan-Guizhou Plateau, we explore agricultural development processes in this area during the Neolithic and Bronze Age. Our results indicate that rice and foxtail millet were cultivated in Shilinggang around 2500 cal a BP. Three phases of prehistoric agricultural development in the Yunnan-Guizhou Plateau can be identified: rice cultivation from 4800–3900 cal a BP, mixed rice and millet crop(foxtail millet and broomcorn millet) cultivation from 3900–3400 cal a BP, and mixed rice, millet crop and wheat cultivation from 3400–2300 cal a BP. The development of agriculture in the Yunnan-Guizhou Plateau during the Neolithic and Bronze Age periods was primarily promoted by prehistoric agriculture expansion across Eurasia, agricultural expansion which was also affected by the topographic and hydrological characteristics of the area.
基金supported by the National Natural Science Foundation of China(Grant No.41930642)。
文摘Landscape evolution is modulated by the regional tectonic uplift,climate change,and river dynamics.However,how to distinguish these mechanisms through the research of surface exhumation and fluvial incision remains controversial.In this study,cosmogenic ^(10)Be,^(26)Al,and ^(21)Ne concentrations in quartz from cave deposits,modern river sediments,and bedrocks were measured to constrain the applicability of cosmogenic ^(21)Ne and discuss Quaternary landscape evolution history in the Guizhou Plateau,southeast China.Using the ^(26)Al-^(10)Be and ^(21)Ne-^(10)Be pairs to distinguish the cosmogenic ^(21)Ne concentration from the excess ^(21)Ne,we found that the nucleogenic ^(21)Ne produced by the U and Th decay in quartz is significant in the samples although there is the possibility of inherited cosmogenic ^(21)Ne.Combining with previous studies,we suggest that the precise approach for applying the cosmogenic ^(21)Ne could be reached by(1)estimating the contribution from nucleogenic ^(21)Ne,(2)avoiding samples with complex burial histories to exclude inherited cosmogenic ^(21)Ne,and(3)combining the ^(10)Be-^(26)Al-^(21)Ne nuclides method for the Quaternary samples.In addition,both pre-burial basin denudation rates and burial ages derived from the ^(26)Al-^(10)Be pair were used to determine the different timescale surface denudation rate and fluvial incision rate in relation to previous work.The consistency of the different timescales pre-burial basin denudation rate,^(36)Cl surface denudation rate,and modern basin denudation rate indicates that the landscape-scale surface denudation has been likely stabilized since the Quaternary in the Guizhou Plateau area.The slightly higher river incision rates than the local surface denudation rate show that the river dynamics may not have reached a steady-state due to the regional tectonic uplift in the Guizhou Plateau.
基金financially supported by the National Key Basic Research and Development Project of China(Grant No.2004CB418301)the National Natural Science Foundation of China(Grant No.40405008).
文摘Analysis of a heavy rainfall in a lower latitude plateau and characteristics of water vapor transportation have been conducted by using conventional data and denser surface data. The results show： （1） the heavy rainfall was caused by a series of mesoscale systems under favorable large-scale conditions when the warm moister air and cold air interacted with each other. At the same time, the coupling between the upper- and lower-level jets was revealed. It is also found that there exists some different characteristics among the main influencing systems of heavy rainfalls in Yunnan, such as the Indian-Myanmar trough and the path of the cold air, compared with those in East and South China. （2） The interaction between mesoscale convergence lines near the ground may be a possible triggering mechanism for the occurrence of mesoscale systems, and the dynamical and thermal dynamical structure of the mesoscale systems was very obvious. The convergence lines may relate closely to the terrain of Yunnan, China. （3） The computation of the water vapor budget reveals that the primary source of water vapor supply for heavy rainfall was in the Bay of Bengal. In this case, the water vapor could be transported into Yunnan even though the amount of water vapor was less than that in the lower troposphere in East and South China. In addition, the analysis for three-dimensional air parcel trajectories better revealed and described the source location and the transportation of water vapor to Yunnan.
文摘It is necessary to understand the aquatic chemical characteristics of natural surfacefresh water for water quality assessment. The chemical data from different kinds of water inthe central Guizhou karst area showed that spring water from carbonate rock cracks (crack-water) is of neutrality or meta-alkalinity and [C] Ca Ⅱ type. The amounts of all ions and theconcentrations of HCO3 and Ca2+ were higher in the autumn than in the spring. the crack-water was influenced by the infiltration of surface water in the process of erosion and/or transportation with decreasing HCO3- and increasing PH, SO, Cl, K+ and Na+ during runningin a certain distance on the land suffice. In particular, the chemical compeitions of the watersat Tianxingqiao (upper-stream), Shuiliandong (mid-waterfall) and Luoshuitan (down-pool)near the Huangguoshu Waterfall were much different from those of the crack-water. The concentrations of , Na+, Fe3+ and NO3- varied closely with seasons. The CaCO3 depositedviolently with CO2 release in the spring. In Lake Hongfeng the HCO3- /So- equivalent ratioswere only 2. 1 - 2. 4, but Ca2 + /Md+ up tO 2. 4 - 4. 2. The CI- concentration increased by afactor Of 1 and Na+ by order of magnitude relative to the spring water. These indicated the in-crease in artificial pollutant discharge in the Lake Hongfeng watershed. In addition, porewater in the soils coveing carbonate rocks belongs to strongly mineralized water. The obvious differences in water quality were controlled by carbonate despition, sulphate mineralization and nitrogen fixation as well as ammonification. It is indicated that the chemical compeitions in thewaters from the karst region were unstable and changeable.
