Carbon isotope ratios (δ^(13)C) of 89 C_4 plant samples were determined fromthe loess area in North China. δ^(13)C values vary between -10.5per thousand and -14.6per thousandwith a mean of -12.6per thousand. Along a...Carbon isotope ratios (δ^(13)C) of 89 C_4 plant samples were determined fromthe loess area in North China. δ^(13)C values vary between -10.5per thousand and -14.6per thousandwith a mean of -12.6per thousand. Along a precipitation gradient from the semi-moist area to thesemiarid area, then to the arid area, the δ^(13)C values of C_4 plants show a slight decreasingtrend. The δ^(13)C values of C_4 plants in the dry season are found lower than those in the wetseason. These trends are opposite to those observed for C_3 species.展开更多
The nature and dynamics of climate change in central Asia since the late Pleistocene are controversial. Moreover,most of the published studies focus mainly on the evolution of moisture conditions, and there have been ...The nature and dynamics of climate change in central Asia since the late Pleistocene are controversial. Moreover,most of the published studies focus mainly on the evolution of moisture conditions, and there have been few attempts to address changes in seasonality. In this study, records of δ^(13)C_(org), TOC, TN, C/N and grain size were obtained from lacustrine sediments at Yili Basin, Xinjiang, NW China. Our aim was to reconstruct the trend in seasonality of precipitation from the last glaciation to the Holocene. The organic matter content of the sediments is derived predominantly from terrestrial plants. The δ^(13)C_(org)values vary from-19.4‰ to-24.8‰, indicating that the vegetation was dominated by C_3 plants. Winter-spring precipitation is identified as the factor determining the relative proportions of C_3 and C_4 plants in the region. A negative trend in δ^(13)C_(org)corresponding to an increase in the relative abundance of C_3 plants indicate a trend of increasing winter-spring precipitation from the last glaciation to the Holocene. The increased incidence of wintertime storms in the interior of Asia is suggested to result in the increase of winterspring precipitation in the Holocene.展开更多
基金supported by the Key Research and Development Program of Shaanxi Province (2020SF-425)the Open Research Fund of State Key Laboratory of Loess and Quaternary Geology,Institute of Earth Environment,CAS(SKLLQG1623)+1 种基金the Open Research Fund of Key Laboratory of Subsurface of Hydrology and Ecological Effect in Arid Region (Chang’an University),Ministry of Education(300102299507)the Natural Science Basic Research Program of Shaanxi (2021JQ-791)。
基金supported by the National Natural Science Foundation of China(Grants Nos.40273006,40072059,49925307 and 90102001).
文摘Carbon isotope ratios (δ^(13)C) of 89 C_4 plant samples were determined fromthe loess area in North China. δ^(13)C values vary between -10.5per thousand and -14.6per thousandwith a mean of -12.6per thousand. Along a precipitation gradient from the semi-moist area to thesemiarid area, then to the arid area, the δ^(13)C values of C_4 plants show a slight decreasingtrend. The δ^(13)C values of C_4 plants in the dry season are found lower than those in the wetseason. These trends are opposite to those observed for C_3 species.
基金supported by the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDB26000000)the National Natural Science Foundation of China (Grant Nos. 41772371, 41572161 & 41730319)+2 种基金the National Basic Research Program of China (Grant No. 2015CB953803)the Youth Innovation Promotion Association CASthe Australian Nuclear Science and Technology Organization
文摘The nature and dynamics of climate change in central Asia since the late Pleistocene are controversial. Moreover,most of the published studies focus mainly on the evolution of moisture conditions, and there have been few attempts to address changes in seasonality. In this study, records of δ^(13)C_(org), TOC, TN, C/N and grain size were obtained from lacustrine sediments at Yili Basin, Xinjiang, NW China. Our aim was to reconstruct the trend in seasonality of precipitation from the last glaciation to the Holocene. The organic matter content of the sediments is derived predominantly from terrestrial plants. The δ^(13)C_(org)values vary from-19.4‰ to-24.8‰, indicating that the vegetation was dominated by C_3 plants. Winter-spring precipitation is identified as the factor determining the relative proportions of C_3 and C_4 plants in the region. A negative trend in δ^(13)C_(org)corresponding to an increase in the relative abundance of C_3 plants indicate a trend of increasing winter-spring precipitation from the last glaciation to the Holocene. The increased incidence of wintertime storms in the interior of Asia is suggested to result in the increase of winterspring precipitation in the Holocene.
