Effect of spatially variable saturated hydraulic conductivity with non-stationary characteristics on the stability of reservoir landslides     

Xue  Yang  Wu  Yiping  Miao  Fasheng  Li  Linwei  Liao  Kang  Ou  Guangzhao 《Stochastic Environmental Research and Risk Assessment (SERRA)》2020,34(2):311-329

Stochastic Environmental Research and Risk Assessment - Conventional landslide analyses, based on deterministic methods or simple random variable methods, cannot consider the spatial variability...  相似文献   

青藏高原凯蒙蛇绿混杂岩中碱性火山岩的发现及意义     

潘政  史仁灯  黄启帅  陈生生  龚小晗  吴钪  杨可 《岩石矿物学杂志》2020,39(1):18-34

班公湖-怒江洋的关闭时间直接制约青藏高原早期构造演化的认识。最近,在班公湖-怒江缝合带南侧凯蒙蛇绿混杂岩中发现一碱性火山岩,岩性主要是橄榄粗安岩,具粗面结构,斑晶主要是更长石和少量普通辉石,基质主要由更长石、普通辉石和少量填隙的碱性长石组成,有的具辉绿结构。岩石化学成分较一致,Si O2含量介于51.34%~53.91%之间,Ti O2含量为1.02%~1.55%,具有高Al2O3(17.06%~18.46%)和Na2O(4.90%~6.36%)、低K2O(0.05%~0.88%)含量特点,大多数Mg#大于60,最高68.62,里特曼指数(σ)介于3.65~4.47之间,为碱性系列火山岩;富集Sr、Rb、Ba等大离子亲石元素,亏损Nb、Y、Yb等高场强元素,相对富集Zr、Ti,Nb/U、Zr/Nb、La/Yb等比值稳定,分别为7.45~8.51、15.92~17.26和7.26~8.06;(87Sr/86Sr)i值变化范围较小,介于0.706~0.707之间,(143Nd/144Nd)t值在0.512 368~0.512 548之间,说明源区较为一致,结合Ce/Pb-Si O2图解判断结果,认为凯蒙碱性火山岩具有原始地幔、陆壳和深海沉积物源区混合特征。锆石U-Pb同位素定年结果表明该火山岩年龄为101.8±1.1 Ma,可能形成于洋壳俯冲阶段末期,由大陆边缘陆壳与俯冲洋壳板片断离导致软流圈地幔上涌诱发部分熔融所致,推测班公湖-怒江洋大约在早白垩世晚期关闭。  相似文献   

毛乌素沙区1961-2016年降水特征     

张雪琴  刘树林  冯坤  郭紫晨  康文平  陈翔  支莹 《中国沙漠》2019,39(6):141-150

基于毛乌素沙区10个气象站1961-2016年观测资料，应用Mann-Kendall方法和t检验法对各气象站年降水量进行了突变检验，借助小波分析讨论了各气象站年降水量的周期特征，根据降水量等值线划分结果对整个研究区分区分析了年、季、月和日尺度上的降水变化特征，并在两个时段上分析了季节性降水的差异。结果表明：毛乌素沙区年降水量空间特征差异明显，东部亚区呈上升趋势，中西部亚区呈下降趋势，但变化趋势不显著且无突变发生；降水年内分配不均，干湿季分明，降水集中在5-9月，夏秋季降水占全年降水比重大，季、月和日尺度降水量存在梯度递减变化；年降水量的年际变化过程存在多重时间尺度的自相似结构；近26年的冬春季降水增加显著，但降水波动幅度小于前30年。  相似文献   

Temperature-Dependent Bifurcated Seasonal Shift of Phytoplankton Community Composition in the Coastal Water off Southwestern Korea     

Kang  Yoonja  Kang  Hee-Yoon  Kim  Dongyoung  Lee  Young-Jae  Kim  Tae-Ik  Kang  Chang-Keun 《Ocean Science Journal》2019,54(3):467-486

Ocean Science Journal - Coastal water around the archipelago off southwestern Korea has been bathed in an unprecedented pool of warm water in summer in recent years. Here, we examined phytoplankton...  相似文献   

地理科学与资源研究所80年回顾及展望     

葛全胜  廖小罕  高星  封志明  刘卫东  廖晓勇  诸云强 《地理学报》2020,75(12):2537-2546

2020年中国科学院地理科学与资源研究所建所80周年。回眸80年,从1940年重庆北碚成立的中国地理研究所,到1953年重新组建的中国科学院地理研究所和1956年成立的中国科学院自然资源综合考察委员会,再到1999年地理研究所和自然资源综合考察委员会整合形成现在的地理科学与资源研究所,几经变迁,历经三代人努力,研究所始终如一,求真务实,开拓进取,推动着地理科学与资源科学的创新发展,为国家建设发展和生态文明进步做出了重要贡献。适逢建所80周年,本文回顾地理资源所发展历程,总结取得的重要科研成果,并展望未来发展。  相似文献   

自然资源综合考察与资源科学综合研究     

孙鸿烈  石玉林  李文华  封志明  江东 《地理学报》2020,75(12):2610-2619

中华人民共和国成立以来,中国的资源科学研究在自然资源考察的基础上形成了一门综合性的学科体系。本文系统总结中国资源科学从自然资源综合考察到资源科学综合研究的发展历程,大致可划分为自然资源综合考察初期（20世纪50—60年代）、区域资源综合科学考察与资源科学研究时期（20世纪70—80年代）、资源科学学科体系的形成与发展时期（20世纪90年代—2000年）及现代资源科学迈向新发展时期（21世纪以来）等4个阶段,促进了中国自然资源的考察和开发利用事业不断向前发展,对中国资源科学形成与发展影响深远。当下面向生态文明建设和美丽中国建设两个国家先进发展需求,资源科学研究要以史为鉴,推陈出新,不断丰富学科的新概念、新知识与新方法,促进资源科学的蓬勃发展。  相似文献   

XTE J1550-564 2001年“迷你爆发”的X射线能谱研究          下载免费PDF全文

葛康  董爱军  刘畅  支启军 《天文学报》2021,62(4):35

黑洞X射线暂现源的迷你爆发是一类峰值光度较低、持续时间较短的爆发.由于观测数据较少,其物理机制仍不清楚.利用RXTE (Rossi X-ray Timing Explorer)卫星从2001年1月28日到3月14日的数据,研究了黑洞X射线暂现源XTE J1550–564 2001年迷你爆发的X射线能谱特性.发现在本次迷你爆发中, XTE J1550–564的X射线能谱可以用幂律谱很好地拟合.整个爆发的硬度强度图不是标准的q型,而是一直保持在最右侧.此外,还分析了此次爆发谱指数Γ与未吸收的2–10 keV能段的X射线流量F_(2–10 keV)的相关性,发现Γ-F_(2–10 keV)呈反相关关系,且谱指数Γ∈[1.35, 1.72].上述结果表明2001年这次爆发一直处于低/硬态,它的X射线辐射主要来自于辐射低效的吸积模式,如ADAF(Advection-Dominated Accretion Flow).  相似文献   

Binary Star Fractions from the LAMOST DR4     

Zhi-Jia Tian  Xiao-Wei Liu  Hai-Bo Yuan  Bing-Qiu Chen  Mao-Sheng Xiang  Yang Huang  Chun Wang  Hua-Wei Zhang  Jin-Cheng Guo  Juan-Juan Ren  Zhi-Ying Huo  Yong Yang  Meng Zhang  Shao-Lan Bi  Wu-Ming Yang  Kang Liu  Xian-Fei Zhang  Tan-Da Li  Ya-Qian Wu  Jing-Hua Zhang 《天文和天体物理学研究(英文版)》2018,(5)

Stellar systems composed of single, double, triple or higher-order systems are rightfully regarded as the fundamental building blocks of the Milky Way. Binary stars play an important role in formation and evolution of the Galaxy. Through comparing the radial velocity variations from multiepoch observations, we analyze the binary fraction of dwarf stars observed with LAMOST. Effects of different model assumptions, such as orbital period distributions on the estimate of binary fractions,are investigated. The results based on log-normal distribution of orbital periods reproduce the previous complete analyses better than the power-law distribution. We find that the binary fraction increases with Teff and decreases with [Fe/H]. We first investigate the relation between α-elements and binary fraction in such a large sample as provided by LAMOST. The old stars with high [α/Fe] dominate with a higher binary fraction than young stars with low [α/Fe]. At the same mass, earlier forming stars possess a higher binary fraction than newly forming ones, which may be related with evolution of the Galaxy.  相似文献   

Regeneration and utilization of nutrients during collapse of a <Emphasis Type="Italic">Mesodinium rubrum</Emphasis> red tide and its influence on phytoplankton species composition     

Yafeng Zhang  Xiuxian Song  Paul J. Harrison  Sheng Liu  Zhiming Yu  Jinjun Kan  Peiyuan Qian  Hao Liu  Kedong Yin 《中国科学:地球科学(英文版)》2018,61(10):1384-1396

High-biomass red tides occur frequently in some semi-enclosed bays of Hong Kong where ambient nutrients are not high enough to support such a high phytoplankton biomass. These high-biomass red tides release massive inorganic nutrients into local waters during their collapse. We hypothesized that the massive inorganic nutrients released from the collapse of red tides would fuel growth of other phytoplankton species. This could influence phytoplankton species composition. We tested the hypothesis using a red tide event caused by Mesodinium rubrum (M. rubrum) in a semi-enclosed bay, Port Shelter. The red tide patch had a cell density as high as 5.0×10⁵ cells L^?1, and high chlorophyll a (63.71 μg L^?1). Ambient inorganic nutrients (nitrate: \(\rm{NO}_3^-\), ammonium: \(\rm{NH}_4^+\), phosphate: \(\rm{PO}_4^{3-}\), silicate: \(\rm{SiO}_4^{3-}\)) were low both in the red tide patch and the non-red-tide patch (clear waters outside the red tide patch). Nutrient addition experiments were conducted by adding all the inorganic nutrients to water samples from the two patches followed by incubation for 9 days. The results showed that the addition of inorganic nutrients did not sustain high M. rubrum cell density, which collapsed after day 1, and did not drive M. rubrum in the non-red-tide patch sample to the same high-cell density in the red tide patch sample. This confirmed that nutrients were not the driving factor for the formation of this red tide event, or for its collapse. The death of M. rubrum after day 1 released high concentrations of \(\rm{NO}_3^-\), \(\rm{PO}_4^{3-}\), \(\rm{SiO}_4^{3-}\), \(\rm{NH}_4^+\), and urea. Bacterial abundance and heterotrophic activity increased, reaching the highest on day 3 or 4, and decreased as cell density of M. rubrum declined. The released nutrients stimulated growth of diatoms, such as Chaetoceros affinis var. circinalis, Thalassiothrix frauenfeldii, and Nitzschia sp., particularly with additions of \(\rm{SiO}_4^{3-}\) treatments, and other species. These results demonstrated that initiation of M. rubrum red tides in the bay was not directly driven by nutrients. However, the massive inorganic nutrients released from the collapse of the red tide could induce a second bloom in low-ambient nutrient water, influencing phytoplankton species composition.  相似文献   

东太平洋海隆13°N表层含金属沉积物物质组成与元素赋存状态     

荣坤波  曾志刚  武力  李康 《海洋科学》2018,42(7):70-79

为了解不同类型含金属沉积物在物质组成和元素赋存状态的差异,对东太平洋海隆13°N洋中脊两侧表层含金属沉积物(站号:E271和E53)进行了矿物学、地球化学分析,顺序提取实验,并与前人对轴部表层沉积物(站号:17A-EPR-TVG1)的研究结果作了对比分析。研究结果表明, E271和E53是远端含金属沉积物,由非浮力热液羽状流中颗粒物沉降所形成的;17A-EPR-TVG1沉积物是近喷口含金属沉积物,由黑烟囱或者热液硫化物丘状体崩塌、堆积,或者由热液羽状流中Fe-Mn氧化物和硫化物快速沉淀而形成的,近喷口沉积物比远端沉积物更富集Fe、Cu和Zn等元素。元素在两种含金属沉积物中的赋存状态基本相同,除了Fe,Cu,Zn,Mo和稀土元素(REE)等元素在远端沉积物中主要存在于Fe-Mn氧化物相,在近喷口沉积物中主要在残留相中。远端沉积物中REE页岩标准化配分模式与海水相似,表明REE主要来自海水,而近喷口沉积物中REE配分模式与热液流体相似,说明REE以高温热液流体来源为主。相关研究结果加深了对热液沉积作用研究的认识。  相似文献