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The Middle and Late Holocene climate change in Bohai Bay revealed by diatom proxy
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作者 Zhiwen SHANG Jianfen LI +1 位作者 Fu WANG Hong WANG 《Journal of Oceanology and Limnology》 SCIE CAS CSCD 2024年第5期1493-1506,共14页
A total of 98 samples from two boreholes in shallow sea area and two oyster reefs in adjacent coastal plain in the northwestern coast of Bohai Bay were collected for diatom analyses and species identification.The rati... A total of 98 samples from two boreholes in shallow sea area and two oyster reefs in adjacent coastal plain in the northwestern coast of Bohai Bay were collected for diatom analyses and species identification.The ratio of the marine species Thalassionema nitzschioides to the intertidal-coastal species complex Cyclotella striata/stylorum serves as a novel proxy for assessing the strength of marine influence.Chronological data,corrected for the local residence time effect,facilitated the construction of a diatom proxy-based marine influence curve for the study area.This curve delineates the dynamics of marine influence and their correlations with paleo-climate fluctuations and the East Asian monsoon variability,as well as their role in chenier formation.Results include:(1)eight periods of intensified marine influence have been documented since 7000 a BP in the study area.The peak of each period,as determined by the diatom proxy,corresponds closely to the warm climatic phases and stronger East Asian summer monsoons,suggesting that the peaks marine influence indicate typically the periods of climatic warmth and monsoon activity intensification in the region;(2)a strong correlation exists between the development of cheniers and marine influence,and chenier formation began with the increasing marine influence and terminated at the end of warm periods as marine influence weakens.The climatic changes in the coastal area,as indicated by the diatom proxy,hold significant potential for future related research endeavors. 展开更多
关键词 Bohai Bay DIATOM diatom-based marine influence curve paleo-climate HOLOCENE
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Paleo-sedimentary environmental restoration and its significance of Chang 7 Member of Triassic Yanchang Formation in Ordos Basin,NW China 被引量:7
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作者 FU Jinhua LI Shixiang +1 位作者 XU Liming NIU Xiaobing 《Petroleum Exploration and Development》 2018年第6期998-1008,共11页
Paleo-sedimentary environment of Chang 7 Member of Upper Triassic Yanchang Formation in Ordos Basin, including the paleoclimate, paleo-salinity and paleo-redox conditions were restored through geochemical elements ana... Paleo-sedimentary environment of Chang 7 Member of Upper Triassic Yanchang Formation in Ordos Basin, including the paleoclimate, paleo-salinity and paleo-redox conditions were restored through geochemical elements analysis of 289 samples collected from the outcrop sections around and wells drilled in the basin and using a series of identification indexes of paleo-climate, paleo-salinity and paleo-redox conditions, such as CaO/MgO?Al2 O3, Sr/Cu, Rb/Sr, Rb/K2 O, Th/U, V/(V+Ni), the content of element B tested from the mudstone. Comprehensive analysis shows that in sedimentary period of the Chang 7, the paleo-climate was warm temperate to subtropical climate with temperature higher than 15 ?C, the water body was continental brackish water to freshwater, and the sediments were deposited under strong reduction conditions. Suitable temperature, extensively deep lake basin and strongly reductive paleo-sedimentary environment led to the blooming, enrichment and preservation of organic matter in the submember Chang 73. As a result, a set of high-quality source rock was formed, laying material foundation for large-scale accumulation of shale oil. 展开更多
关键词 paleo-climate paleo-salinity paleo-redox conditions element geochemistry paleo-sedimentary environment CHANG 7 MEMBER Upper TRIASSIC ORDOS Basin
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Spatiotemporal variation in leaf size and shape in response to climate 被引量:9
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作者 Yaoqi Li Dongting Zou +4 位作者 Nawal Shrestha Xiaoting Xu Qinggang Wang Wen Jia Zhiheng Wang 《Journal of Plant Ecology》 SCIE CSCD 2020年第1期87-96,共10页
Aims Morphological variation of leaves is a key indicator of plant response to climatic change.Leaf size and shape are associated with carbon,water and energy exchange of plants with their environment.However,whether ... Aims Morphological variation of leaves is a key indicator of plant response to climatic change.Leaf size and shape are associated with carbon,water and energy exchange of plants with their environment.However,whether and how leaf size and shape responded to climate change over the past decades remains poorly studied.Moreover,many studies have only explored inter-but not intraspecific variation in leaf size and shape across space and time.Methods We collected>6000 herbarium specimens spanning 98 years(1910–2008)in China for seven representative dicot species and measured their leaf length and width.We explored geographical patterns and temporal trends in leaf size(i.e.leaf length,leaf width and length×width product)and shape(i.e.length/width ratio),and investigated the effects of changes in precipitation and temperature over time and space on the variation in leaf size and shape.Important Findings After accounting for the effects of sampling time,leaf size decreased with latitude for all species combined,but the relationship varied among species.Leaf size and shape were positively correlated with temperature and precipitation across space.After accounting for the effects of sampling locations,leaf size of all species combined increased with time.Leaf size changes over time were mostly positively correlated with precipitation,whereas leaf shape changes were mostly correlated with temperature.Overall,our results indicate significant spatial and temporal intraspecific variation in leaf size and shape in response to climate.Our study also demonstrates that herbarium specimens collected over a considerable period of time provide a good resource to study the impacts of climate change on plant morphological traits. 展开更多
关键词 climate change geographical patterns herbarium specimens leaf traits paleo-climate reconstruction
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Geochemical study of boron isotopes in the process of loess weathering
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作者 赵志琦 刘丛强 +1 位作者 肖应凯 郎赟超 《Science China Earth Sciences》 SCIE EI CAS 2003年第2期106-116,共11页
In this paper the boron contents and boron isotopic composition ofacid-soluble phases in loess and paleosol samples are determined for the first time. The boroncontents of acid-soluble phases in the Luochuan loess sec... In this paper the boron contents and boron isotopic composition ofacid-soluble phases in loess and paleosol samples are determined for the first time. The boroncontents of acid-soluble phases in the Luochuan loess section (S_0—S_2) vary within the range of(0.8—2.7)x10^(-6) and their δ^(11)B values vary from -1.8 per thousand to +18.6 per thousand,mostly within the range of 0—+10 per thousand. The boron contents and δ^(11)B values of paleosollayers are higher than those of loess layers, especially in the loess layer S_1. Varying chemicalweathering intensity and loess adsorption capability are the main factors leading to the variationsof boron contents and δ^(11)B values of acid-soluble phases in the loess section. The variation ofchemical weathering intensity in response to the variation of climatic conditions seems to be themain factor leading to the variations of boron contents and δ^(11)B values of acid-soluble phasesin the loess section. 展开更多
关键词 LOESS-PALEOSOL boron isotopic composition chemical weathering adsorption paleo-climate
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