~(10)Be exposure ages of Quaternary Glaciers in Antarctica     

WangJing Ni  ZhiGang Zhang  JingXue Guo  XueYuan Tang 《寒旱区科学》2021,13(4):292-298

In situ terrestrial cosmogenic nuclides(TCN) have been widely applied to date the ages of Quaternary glacial deposits in Antarctica and plays an important role in reconstructing the glacial evolution and climate change. It helps to understand the Antarctic ice sheet's evolution process in Quaternary and shed light on the application of Cosmogenic Nuclide exposure dating technique in glacial geomorphology. In this paper, we retrieved 49510 Be age samples in Antarctica from literature published between 2004 and 2020 and recalculated the TCN ages using version 3.0 online calculator of Cosmic-Ray Produced Nuclide Systematics on Earth(CRONUS-Earth). Several conclusions can be drawn from the results:(1) 75% of the exposure ages are younger than 400 ka, and 91% younger than 1, 100 ka. Northern Antarctic Peninsula exposure result is visibly younger than the main glaciers area in East Antarctica due to climate change and geological evaluation since the LGM(Last Glacial Maximum).(2) TCN ages are relevant to the samples' relative positions in the Antarctic continent, but a relationship between their ages and elevations is yet to be determined based on the collected data.  相似文献   

Growth marks in eyestalks of Portunus trituberculatus:A development of technique and evidence of molting     

Bilin Liu  Jian Zhang  Jiang Rui  Zhenyu Ni  Chang Shu 《海洋学报(英文版)》2021,40(4):84-91

The analysis of growth bands in the eyestalk has been increasingly used for estimating crustacean ageing and molting. In this study, we developed an effective method to process and observe the eyestalk microstructure of the swimming crab(Portunus trituberculatus). We found that dark pigmentation as a result of boiling has an influence on the observation of the eyestalk microstructure. Choosing an unboiled eyestalk, this study compared the cross section and longitudinal section, and concluded that the cross section is suitable for the observation of growth increments with 6.1% CV(coefficient of variation), and growth bands are suitable for the observation of the longitudinal section with 5.4% CV. The width of growth increments near the edge of the endocuticle is small, and the width of growth increments of the middle part of the endocuticle is large. Relationship of number of growth bands to molting time was fitted to a linear function with the slope not significantly different from 1, indicating that growth bands are formed associated with molting. Periodicity of growth increment formation was calculated as 3.7 d, however was not verified. Our results provide a new improved technique for identification of crustacean molting and growth.  相似文献   

粤港澳大湾区海洋生态环境协同共治策略探讨          下载免费PDF全文

郑淑娴  杨黎静  吴霓  章柳立  陈绵润 《海洋开发与管理》2020,37(6):48-54

粤港澳三地为共同应对跨境污染等环境问题开始携手,经过多年的交流深化,已形成总体规划引领,合作框架协议约束,联席会议与粤港、粤澳环保合作小组及其下设的专题小组相结合的海洋环境协同共治平台。目前,粤港澳大湾区仍面临海域水质不断恶化、湿地生态功能退化、海洋生物资源衰退等严峻的生态问题。通过系统梳理,借鉴国际三大湾区先进经验,提出健全大湾区海洋生态环境协同治理法制体系、完善协同共治平台、统筹规划海洋生态环境保护、健全公众参与制度等策略,完善大湾区海洋生态环境协同共治机制。  相似文献   

Land use/cover changes and environmental consequences in Songnen Plain, Northeast China   总被引：4，自引：2，他引：2  

Dianwei Liu  Zongming Wang  Kaishan Song  Bai Zhang  Liangjun Hu  Ni Huang  Sumei Zhang  Ling Luo  Chunhua Zhang  Guangjia Jiang 《中国地理科学(英文版)》2009,19(4):299-305

The Songnen Plain in Northeast China, one of the key national bases of agricultural production, went through remarkable land use/cover changes in recent years. This study aimed to explore the long-term land use/cover changes and the effects of these changes on the environment. The Landsat-based analysis showed that, during 1986–2000, cropland, built-up land and barren land had increased, among which cropland had the largest increase of 9,198km² with an increase rate of 7.5%. Woodland, grassland, water body and swampland had decreased correspondingly, among which grassland had the most dramatic decrease of 6,127km² with a decrease rate of 25.6%. The transition matrix results revealed that grassland, woodland and swampland were the three main land use types converted to cropland. Climate warming created the potential environment for the conversion of grassland and swampland into cropland. Land resources policy made by central and provincial governments of China affected the pattern and intensity of land use. Land use/cover changes accompanied by climatic variation brought out a series of environmental consequences, such as sand desertification of land, land salinization and alkalinization, grassland degradation, and more frequent floods. Under this circumstance, optimized land use structure and restoration measures are needed.  相似文献   

Hybrids between olive flounder Paralichthys olivaceus and stone flounder Kareius bicoloratus： karyotype, allozyme and RAPD analyses   总被引：2，自引：0，他引：2  

尤锋  王伟  徐冬冬  朱香萍  倪静  吴志昊  徐永立  王新成  张培军 《中国海洋湖沼学报》2009,27(2):317-323

The hybrid between olive flounder Paralichthys olivaceus and stone flounder Kareius bicoloratus was produced by artificial insemination of olive flounder eggs with stone flounder sperm. Sinistral and dextral are two types of hybrid progeny after metamorphosis. Karyotypes of both hybrid flounders are the same as those of the two parental species. Of the 22 loci examined from 12 allozymes, 12 confirmed hybridization of the paternal and maternal loci in hybrids and no difference was found in allozyme patterns of sinistral and dextral hybrid fishes. RAPD patterns of these specimens were also studied with 38 primers selected from 104 tested. Among them, the PCR products of 30 primers showed hybridization of the paternal and maternal bands. Genetic variation between hybrids and their parental stocks was analyzed by RAPD using 10 of the above 38 primers. The average heterozygosity and genetic distance were calculated. The results suggested that the filial generation could inherit a little more genetic materials from paternal fish than that from maternal fish. Supported by National Natural Science Foundation of China (No. 30571445), National High-Technology Research and Development Program (863 Program, No. 2006AA10A404), and Project from the Ministry of Science and Technology of China (No. 2006DKA30470-017)  相似文献   

OFDM系统导频信道估计内插算法研究(英文)   总被引：1，自引：0，他引：1  

王昵  邓平 《成都信息工程学院学报》2008,23(2):141-146

为保证OFDM系统的性能不受信道的多径和衰落效应的影响,需要采用信道估计的方法来跟踪信道响应的变化。目前使用比较多的是导频辅助信道估计,首先利用某种估计算法得到导频处信道响应,再通过某种一维或二维的内插算法获得完整的信道响应。研究了各种内插算法,包括常值内插、线性内插、高斯内插、Cubic内插、Sinc内插和变换域内插,并对各算法在不同信道环境下进行了仿真比较。  相似文献   

黄河流域水蚀区土壤侵蚀空间尺度效应分析   总被引：3，自引：0，他引：3  

李秀霞  李天宏  倪晋仁 《地理科学进展》2008,27(6):49-56

以黄河、延河、杏子河、纸坊沟四级流域尺度为例,应用信息熵原理分析了各级流域尺度上土壤水力侵蚀与 其影响因子之间的空间相关性,通过比较各因子在不同空间尺度上与土壤侵蚀的相关性,定量分析了土壤侵蚀过 程的空间尺度效应。分析结果给出了降雨、地形、土质、植被等因子在不同流域尺度上对土壤侵蚀的影响大小,以及 每个尺度上各影响因子重要性的主次顺序。总体而言,随着流域空间尺度的增大,各因子对土壤侵蚀的影响具有放 大或缩小效应,影响因素的主次顺序随之易位,其中微观因子的控制作用有所减小,而宏观因子的控制作用则逐渐 突显。本文建立的流域土壤侵蚀空间尺度效应的定量分析方法和分析结果有助于解决当前土壤侵蚀评估模型普遍 存在的尺度转化和区域通用性问题。  相似文献   

Survey and cause analyses of ground surface deformation near a foundation pit slope: a case study in the Three Gorges area,China     

Guangcheng Zhang  Ni Xie  Huiming Tang  Lu Zhang  Jiangpeng Wu 《Natural Hazards》2015,75(1):13-31

  相似文献   

A very bright (i=16.44) quasar in the ‘redshift desert' discovered by the Guoshoujing Telescope (LAMOST)     

Xue-Bing Wu  Zhao-Yu Chen  Zhen-Dong Jia  Wen-Wen Zuo  Yong-Heng Zhao  A-Li Luo  Zhong-Rui Bai  Jian-Jun Chen  Hao-Tong Zhang  Hong-Liang Yan  Juan-Juan Ren  Shi-Wei Sun  Hong Wu  Yong Zhang  Ye-Ping Li  Qi-Shuai Lu  You Wang  Ji-Jun Ni  Hai Wang  Xu Kong  Shi-Yin Shen 《中国天文和天体物理学报》2010,10(8)

The redshift range from 2.2 to 3 is known as the ‘redshift desert' of quasars because quasars with redshifts in this range have similar optical colors as normal stars and are thus difficult to find in optical sky surveys.A quasar candidate, SDSS J085543.40001517.7, which was selected by a recently proposed criterion involving near-IR Y-K and optical g-z colors, was identified spectroscopically as a new quasar with a redshift of 2.427 by the Guoshoujing Telescope (LAMOST) commissioning observation in 2009 De...  相似文献   

小麦生物量和真实叶面积指数的高光谱遥感估算模型   总被引：5，自引：0，他引：5  

侯学会  牛铮  黄妮  许时光 《国土资源遥感》2012,(4):30-35

利用大田小麦的参数数据和冠层光谱数据,基于光谱一阶微分技术和光谱响应函数,构建等效MODIS植被指数,建立小麦生物量(本文指总干生物量,下同)和真实叶面积指数的高光谱遥感估算模型.结果表明:①小麦生物量与冠层光谱在552 nm,721 nm处呈现最显著相关关系,叶面积指数与冠层光谱的相关性在400～1100 nm范围内较显著;②红边位置与生物量的关系最为显著,相关系数R为0.818;③6种等效MODIS植被指数中,增强型植被指数对生物量最为敏感;④红边位置估算小麦总生物量的指数模型最优,决定系数R2为0.829;⑤增强型植被指数与小麦叶面积指数的指数模型拟合度最强,决定系数R2为0.94.利用实测光谱模拟MODIS等效反射率构建植被指数反演小麦参数的方法,可为利用卫星数据进行大面积、无破坏和及时获取地面植被信息研究提供重要手段.  相似文献