Spatiotemporal characteristics of Qinghai Lake ice phenology between 2000 and 2016     

Qi  Miaomiao  Yao  Xiaojun  Li  Xiaofeng  Duan  Hongyu  Gao  Yongpeng  Liu  Juan 《地理学报(英文版)》2019,29(1):115-130

Journal of Geographical Sciences - Lake ice phenology is considered a sensitive indicator of regional climate change. We utilized time series information of this kind extracted from a series of...  相似文献   

Hydrological cycle and water balance estimates for the megadune–lake region of the Badain Jaran Desert,China          下载免费PDF全文

Yan‐Dong Ma  Jing‐Bo Zhao  Xiao‐Qing Luo  Tian‐Jie Shao  Zhi‐Bao Dong  Qi Zhou 《水文研究》2017,31(18):3255-3268

The hydrology and water balance of megadunes and lakes have been investigated in the Badain Jaran Desert of China. Field observations and analyses of sand layer water content, field capacity, secondary salt content, and grain size reveal 3 types of important natural phenomenon: (a) vegetation bands on the leeward slope of the megadunes reflect the hydrological regime within the sandy vadose zone; (b) seepage, wet sand deposits, and secondary salt deposits indicate the pattern of water movement within the sandy vadose zone; (c) zones of groundwater seeps and descending springs around the lakes reflect the influence of the local topography on the hydrological regime of the megadunes. The seepage exposed on the sloping surface of the megadunes and gravity water contained within the sand layer confirm the occurrence of preferential flow within the vadose zone of the megadunes. Alternating layers of coarse and fine sand create the conditions for the formation of preferential flows. The preferential flows promote movement of water within the sand layer water that leads to deep penetration of water within the megadunes and ultimately to the recharging of groundwater and lake water. Our results indicate that a positive water balance promotes recharge of the megadunes, which depends on the high permeability of the megadune material, the shallow depth of the surface sand layer affected by evaporation, the occurrence of rainfall events exceeding 15 mm, and the sparse vegetation cover. Water balance estimates indicate that the annual water storage of the megadunes is about 7.5 mm, accounting for only 8% of annual precipitation; however, the shallow groundwater per unit area under the megadunes receives only 3.6% of annual precipitation, but it is still able to maintain a dynamic balance of the lake water. From a water budget perspective, the annual water storage in the megadunes is sufficient to serve as a recharge source for lake water, thereby enabling the long‐term persistence of the lakes. Overall, our findings demonstrate that precipitation is a significant component of the hydrological cycle in arid deserts.  相似文献   

Lake sedimentary processes and vegetation changes over the last 45k cal a bp in the uplands of south-eastern Amazonia     

José Tasso Felix Guimarães  Prafulla Kumar Sahoo  Mariana Maha Jana Costa De Figueiredo  Karen da Silva Lopes  Markus Gastauer  Silvio Junio Ramos  Cecilio Frois Caldeira  Pedro Walfir M. Souza-Filho  Luiza Santos Reis  Marcio Sousa Da Silva  Paulo Rogenes Pontes  Renato Oliveira Da Silva Junior  Tarcísio Magevski Rodrigues 《第四纪科学杂志》2021,36(2):255-272

This study addresses paleoclimate influences in a southern Amazonia ecotone based on multiproxy records from lakes of the Carajás region during the last 45k cal a bp. Wet and cool environmental conditions marked the initial deposition in shallow depressions with detrital sediments and high weathering rates until 40k cal a bp. Concomitantly, forest and C3 canga plants, along with cool-adapted taxa, developed; however, short drier episodes enabled expansion of C4 plants and diagenetic formation of siderite. A massive event of siderite formation occurred approximately 30k cal a bp under strong drier conditions. Afterwards, wet and cool environmental conditions returned and persisted until the Last Glacial Maximum (LGM). The LGM was marked by lake-level lowstands and subaerial exposure. The transition from the LGM to the Holocene is marked by the onset of oscillations in temperature and humidity, with an expansion of forest and canga plants. Cool taxa were present for the last time in the Carajás region ~ 9.5–9k cal a bp. After 10k cal a bp , shallow lakes became upland swamps due to natural infilling processes, but the current vegetation types and structures of the plateaus were acquired only after 3k cal a bp under wetter climatic conditions.  相似文献   

Developing millennial tree ring chronologies in the fire‐prone North American boreal forest     

DOMINIQUE ARSENEAULT  BENJAMIN DY  FABIO GENNARETTI  JULIA AUTIN  YVES BÉGIN 《第四纪科学杂志》2013,28(3):283-292

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乌南油田滨浅湖砂体储层构型及其油气意义          下载免费PDF全文

石金华  韩登林  于炳松  李仕远  王宝  陈景华 《地质科学》2016,(4):1310-1323

基于Miall储层构型研究思想,结合岩心、测井、测试等资料,对乌南油田砂坝砂体储层构型界面特征进行了研究,确定了储层构型界面识别标志;在此基础上,将砂坝内部构型分为坝主体和坝侧缘,同时通过动、静态结合,明确砂坝外部构型存在孤立、视连通、左侧向叠置和右侧向叠置4种模式;纵向上发育湖退（进积）和湖进（退积）两种砂体发育模式。坝主体是主力储层,具有良好油气显示;坝主体分布面积大、出现频率高为油气有利区域。  相似文献   

云蒙湖流域不同坡度的土壤侵蚀特征     

泮雪芹  于兴修  孟晓云 《测绘科学》2016,41(8):63-66

针对定量分析土壤侵蚀在各坡度等级上的空间分布研究较少的现状,该文选用通用的土壤流失预报方程,对云蒙湖流域1986—2010年间的土壤水力侵蚀状况进行了定量的估算,以探讨不同坡度上的土壤侵蚀特征,并进一步分析了土壤侵蚀变化与人类活动的关系。分析得出:土壤侵蚀强度发生在人类活动比较频繁的区域上(8~25°坡度)更为严重;2010年比1986年强度以上所占比例在15°坡度等级上相对更低,在15°坡度等级上有所增加;云蒙湖流域主要土壤侵蚀量发生在25°坡度上;2010年比1986年耕地面积减少、林地和居民用地面积增加是土壤侵蚀降低的主要因素。  相似文献   

鄂尔多斯盆地晚三叠世延长期古湖盆生物相带划分及地质意义     

杨华  傅强  齐亚林  周新平  龚宁  黄少雄 《沉积学报》2016,34(4):688-693

鄂尔多斯盆地晚三叠世发育大型坳陷型湖盆。湖水的升降影响着湖盆水体面积的大小、深浅以及沉积体系发育分布,进而影响全盆地晚三叠延长统地层生储盖组合的发育特征。通过野外剖面、钻井岩芯中古生物化石的鉴定,结合古生物组合特征对鄂尔多斯盆地晚三叠世湖盆的古生物生态环境进行了恢复。确定鄂尔多斯晚三叠世湖盆是一个最大水深不超过60 m的浅水湖盆,属于温暖潮湿的淡水-半咸水环境。从湖岸到湖心,可以划分为预测古水深1～2 m的河流-沼泽生物相带;预测古水深3～15 m的滨岸-河口三角洲生物相带;预测古水深15～35 m的浅湖生物相带;预测古水深在35～60 m范围的半-深湖生物相带。这些生物相带的划分,为恢复鄂尔多斯盆地晚三叠世时期的岩相古地理奠定了基础,为盆地延长组沉积边界、盆地内沉积体系发育展布以及沉积相带的划分提供了坚实的地质依据,具有理论与实际意义。  相似文献   

赛里木湖沉积物有机质变化特征及其环境信息   总被引：3，自引：0，他引：3  

陈京  吉力力·阿不都外力  马龙 《冰川冻土》2016,38(3):761-768

在分析赛里木湖湖泊沉积物中氮含量(TN)、有机碳含量(TOC)及其碳同位素(δ~(13)C_(org))以及色素等指标的变化特征的基础上,结合沉积物中有机指标的环境意义的探讨,揭示了新疆赛里木湖湖泊沉积物中有机质所蕴含的环境信息.赛里木湖沉积物中总有机碳含量、总氮含量的变化反映了流域初级生产力的变化,沉积物色素变化是有机质保存条件的指标,间接指示了湖泊-流域水热配置环境.有机碳同位素(δ~(13)C_(org))反映了湖泊内外源的混合信息.结合有序样品聚类分析方法,可以将赛里木湖近代环境划分为四大发展阶段:1、各有机指标相对稳定;2、各有机指标明显波动;3、各有机指标显著增加;4、各有机指标快速增加.  相似文献   

季节性冰封热融浅湖水温原位观测及其分层特征   总被引：1，自引：0，他引：1       下载免费PDF全文

黄文峰  韩红卫  牛富俊  李志军 《水科学进展》2016,27(2):280-289

为探究季节性冰封浅湖热力学特征,于2010年10月至2013年7月对高原腹地一典型热融湖塘冰层生消、水/冰温及气象条件开展原位观测,分析了水温分布时间变化、温跃层以及冰生消对水温结构的影响。结果发现:冰面升华显著,贯穿整个冰期;水温日变化、季节变化和垂直结构受气温、大气辐射、风速、冰生消和湖底沉积层热贡献影响显著;在"无冰期-结冰前-冰生长期-冰融化期-融化后-无冰期"年循环过程中水温垂直结构分别呈现出"分层-翻转-逆温分层-逆温与正温共存-翻转-分层"的循环过程。分层期水温结构仅由上部混合层和温跃层构成,且偶因强风搅动而全湖翻转混合。可见,相比大中型湖泊,季节性冰封浅湖热力学结构差异显著。  相似文献   

尕斯库勒盐湖中CO_2-卤水-盐岩相互作用模拟研究     

韩积斌  许建新  海擎宇  安朝  何天丽  马海州 《铀矿地质》2016,(1):54-59

利用PHREEQC软件模拟CO2侵入后,尕斯库勒盐湖中CO2-卤水-岩盐之间的相互作用。CO2侵入卤水层后,卤水中元素的化学形态种类和大小发生变化,特别是碳酸盐型的络合物形态增多。CO2侵入后,除了碳酸盐、石盐和硫酸盐矿物达到饱和被析出外,其余矿物的不饱和程度加剧,卤水的TDS增大,pH值减小。卤水中U的含量在CO2侵入后发生沉淀而减小。研究成果对深入评估区域内盐水层CO2地质封存的环境风险和利用CO2分离提取盐湖卤水中的铀元素提供理论依据。  相似文献