柴达木盆地碱山深钻的硼同位素地球化学特征          下载免费PDF全文

卢胜城  韩文霞  韩凤清  马云麒  吕爽 《盐湖研究》2020,28(1):60-68

沉积物硼(B)同位素组成可以反映其地质成因及经历的地质过程,因此在许多领域的研究中都有较为广泛的应用。通过对位于柴达木盆地碱山背斜顶部的SG-1b钻孔沉积物(7.3～1.6 Ma)水溶组分的B同位素研究,发现钻孔沉积物B含量在38.55～172.3μg/g之间,平均含量为87.6μg/g;δ~(11)B值的变化范围在3.61‰～16.26‰之间,平均值为10.65‰,B含量与δ~(11)B值具有一定的正相关关系。进一步分析表明,受到碱山背斜构造隆升以及晚新生代以来气候干旱化的影响,柴西古湖逐渐咸化萎缩,沉积环境以及碳酸盐含量、粘土矿物含量及其矿物组合等也在发生变化,B含量和δ~(11)B值自钻孔底部向上的逐步增加以及后期的急剧增加,与水溶离子含量以及矿物和粒度等的变化一致,这说明柴达木盆地晚中新世以来湖泊沉积物的B含量和δ~(11)B值可以很好地反映研究区气候和湖水的演化过程,共同指示了研究区自7.3 Ma以来气候的持续干旱化和湖水盐度的逐步增加,以及3.3Ma以来干旱化和湖水浓缩过程的加剧。  相似文献   

Application of Glycerol Dialkyl Glycerol Tetraether Lipids in Paleoenvironment Reconstruction of Loess Deposits: A Review of Recent Progresses     

Shaohua Tian  Guoqiao Xiao  Huan Yang 《地球科学进展》2020,35(5):465-477

The Glycerol Dialkyl Glycerol Tetraethers (GDGTs) occur ubiquitously in a wide range of environments, such as loess, peat, lake, soil, and ocean, which vary compositionally in response to environmental changes, and provide a series of biomarker proxies for paleoenvironmental reconstruction. This paper introduced the structures and biological sources of GDGTs, and reviewed the recent progresses of the application of the GDGTs proxies in the paleoenvironmental reconstruction of loess deposits. The main progresses include: \mathrm{①} The GDGTs proxies have been widely used in reconstructing the climate changes in loess deposits, and have established the temperature changes of last 800 ka for the Chinese Loess Plateau; \mathrm{②}Temperature variations in Chinese Loess Plateau displayed significant correlation with the Northern Hemisphere insolation, which may be also regulated by the surface vegetation conditions; and \mathrm{③} In the Chinese Loess Plateau, the increase in monsoon precipitation during the last deglaciation significantly lagged behind the rise of temperature. However, problems still exist in the current studies. For instance, the GDGTs-based temperature is likely overestimated, probably reflecting the temperature of warm season, and relationships between GDGT indices and climate factors are still unclear. In the future, the development of new proxies and more accurate regional calibrations based on the separation of 6- methyl GDGTs are expected to provide more reliable paleoenvironmental information, and will provide essential evidence for the evolution of hydrothermal pattern and mechanisms behind climate changes in different regions.  相似文献   

Microseism Variations in Response to Antarctic Seasonal Changes in Sea Ice Extent     

XU Xiaoqing  LIN Jianmin  FANG Sunke 《中国地震研究》2020,34(2):264-284

The temporal and spatial distributions of Antarctic sea ice play important roles in both the generation mechanisms and the signal characteristics of microseisms. This link paves the way for seismological investigations of Antarctic sea ice. Here we present an overview of the current state of seismological research about microseisms on Antarctic sea ice. We first briefly review satellite remote-sensing observations of Antarctic sea ice over the past 50 years. We then systematically expound upon the generation mechanisms and source distribution of microseisms in relation to seismic noise investigations of sea ice, and the characteristics of Antarctic microseisms and relationship with sea ice variations are further analyzed. We also analyze the continuous data recorded at seismic station BEAR in West Antarctica from 2011 to 2018 and compare the microseism observations with the corresponding satellite remote-sensing observations of Antarctic sea ice. Our results show that:(1) the microseisms from the coastal regions of West Antarctica exhibit clear seasonal variations, SFM with maximum intensities every April-May and minimum intensities around every October-November; while DFM intensities peak every February-March, and reach the minimum around every October. Comparatively, the strong seasonal periodicity of Antarctic sea ice in better agreement with the observed DFM; and (2) microseism decay is not synchronous with sea ice expansion since the microseism intensity is also linked to the source location, source intensity (e.g., ocean storms, ocean wave field), and other factors. Finally, we discuss the effect of Southern Annular Mode on Antarctic sea ice and microseisms, as well as the current limitations and potential of employing seismological investigations to elucidate Antarctic sea ice variations and climate change.  相似文献   

Characterization of Ethiopian mega hydrogeological regimes using GRACE,TRMM and GLDAS datasets     

《Advances in water resources》2014

Understanding the spatio-temporal characteristics of water storage changes is crucial for Ethiopia, a country that is facing a range of challenges in water management caused by anthropogenic impacts as well as climate variability. In addition to this, the scarcity of in situ measurements of soil moisture and groundwater, combined with intrinsic “scale limitations” of traditional methods used in hydrological characterization are further limiting the ability to assess water resource distribution in the region. The primary objective of this study is therefore to apply remotely sensed and model data over Ethiopia in order to (i) test the performance of models and remotely sensed data in modeling water resources distribution in un-gauged arid regions of Ethiopia, (ii) analyze the inter-annual and seasonal variability as well as changes in total water storage (TWS) over Ethiopia, (iii) understand the relationship between TWS changes, rainfall, and soil moisture anomalies over the study region, and (iv) identify the relationship between the characteristics of aquifers and TWS changes. The data used in this study includes; monthly gravity field data from the Gravity Recovery And Climate Experiment (GRACE) mission, rainfall data from the Tropical Rainfall Measuring Mission (TRMM), and soil moisture from the Global Land Data Assimilation System (GLDAS) model. Our investigation covers a period of 8 years from 2003 to 2011. The results of the study show that the western part and the north-eastern lowlands of Ethiopia experienced decrease in TWS water between 2003–2011, whereas all the other regions gained water during the study period. The impact of rainfall seasonality was also seen in the TWS changes. Applying the statistical method of Principal Component Analysis (PCA) to TWS, soil moisture and rainfall variations indentified the dominant annual water variability in the western, north-western, northern, and central regions, and the dominant seasonal variability in the western, north-western, and the eastern regions. A correlation analysis between TWS and rainfall indicated a minimum time lag of zero to a maximum of six months, whereas no lag is noticeable between soil moisture anomalies and TWS changes. The delay response and correlation coefficient between rainfall and TWS appears to be related to recharge mechanisms, revealing that most regions of Ethiopia receive indirect recharge. Our results also show that the magnitude of TWS changes is higher in the western region and lower in the north-eastern region, and that the elevation influences soil moisture as well as TWS.  相似文献   

威海沿岸海域潮汐特征分析          下载免费PDF全文

邹曙光  刘李钊 《海洋开发与管理》2018,35(5):83-86

文章主要选取国家海洋局成山头海洋环境监测站1996—2016年的潮位、潮差月值资料,利用线性回归法,对威海沿岸海域近21年来的潮汐特征进行分析。结果表明:威海沿岸海域近21年的平均潮位、最高潮位、最低潮位、平均潮差、最大潮差整体上均呈上升的变化趋势,但气候倾向率各不相同,分别是2.57cm/(10a)、5.872cm/(10a)、4.137cm/(10a)、1.017cm/(10a)、2.604cm/(10a)。  相似文献   

基于 MODIS 数据的吐鲁番盆地 2001—2017 年 植被变化及水热组合影响分析          下载免费PDF全文

庞冉  王文 《干旱区地理》2020,43(5):1242-1252

中国西北干旱地区的气候变化及其对植被的影响一直备受关注。以地形特殊的吐鲁番盆 地为研究对象，利用实测气象站点数据、再分析气象格点数据以及 MODIS 卫星遥感植被指数，采用 趋势检验、线性回归、偏相关分析等方法，探究了该地区 2001—2017 年间的植被变化及其与水热组 合特征之间的关系。结果表明：（1）吐鲁番盆地降水量整体没有显著变化，但北部山区降水增长较 多，气温总体呈显著上升趋势，尤其是盆地底部中心区域增温较大。（2）全区域植被指数（NDVI）总 体呈极显著上升趋势，山区及中心区域 NDVI 增长率较大。（3）受水汽来源和日照时长的影响，吐鲁 番盆地周边山区高程 3 000 m 左右 NDVI 值最高，山区植被最好的坡向是西北坡。（4）吐鲁番盆地水 热组合复杂，水分条件是大部分地区植被生长的主要限制因素，降水与 NDVI 有较好的正相关，在 山区和荒漠区热量增加不利于植被生长，但中心区域受地下水和人类活动影响，水分的供给相对 稳定，热量增加利于植被生长。  相似文献   

Historical manufacturing volatility and local sustainability efforts: A link to the past     

《Global Environmental Change》2022

Renewed attention to the role of subnational efforts in addressing myriad environmental challenges necessitates a greater understanding of the factors associated with program adoption. Given observed relationships between adoption of sustainability practices and the presence of carbon-intensive industry, and separately the observed persistence of industrial history in a given place, we explore the link between historical manufacturing employment volatility and current sustainability plan adoption at the local level. Our analysis suggests that the magnitude of changes in manufacturing employment is inversely related to the likelihood of sustainability plan adoption. Our analysis further suggests that, given the same pace of change, counties with shrinking manufacturing employment are more likely to adopt sustainability plans than those with growing employment. Lastly, we find that the link between past industrial transitions and local sustainability commitment is moderated by local disaster experience and priority for environmental protection. Collectively, the findings also shed light on potential—and otherwise unobservable—barriers to transitions to sustainable practices at the local level. In particular, the inverse relationship between pace of employment change and plan adoption suggests that minimizing the rapidity of contemporary transitions may counterintuitively ease the eventual adoption of sustainability-related policies.  相似文献   

Navigating climate crises in the Great Barrier Reef     

《Global Environmental Change》2022

A dramatic escalation of extreme climate events is challenging the capacity of environmental governance regimes to sustain and improve ecosystem outcomes. It has been argued that actors within adaptive governance regimes can help to steer environmental systems toward sustainability in times of crisis. Yet there is little empirical evidence of how acute climate crises are navigated by actors operating within adaptive governance regimes, and the factors that influence their responses. Here, we qualitatively assessed the actions key governance actors took in response to back-to-back mass coral bleaching – an extreme climate event – of the Great Barrier Reef in 2016 and 2017, and explored their perceptions of barriers and catalysts to these responses. This research was, in part, a product of collaboration and knowledge co-production with Great Barrier Reef governance actors aimed at improving responses to climate crises in the region. We found five major categories of activity that actors engaged with in the wake of recurrent mass coral bleaching: assessing the scale and extent of bleaching, sharing information, communicating bleaching to the public, building local resilience, and addressing global threats. These actions were both catalyzed and hindered by a range of factors that fall within different domains of adaptive capacity; such as assets, social organization, and agency. We discuss the implications of our findings as they relate to existing research on adaptive capacity and adaptive governance. We conclude by coalescing insights from our interviews and a participant engagement process to highlight four key ways in which the ability of governance actors, and the Great Barrier Reef governance regime more broadly, can be better prepared for, and more effectively respond to extreme climate events. Our research provides empirical insight into how crises are experienced by governance actors in a large-scale environmental system, potentially providing lessons for similar systems across the globe.  相似文献   

Can we learn from the past? Towards better analogies and historical inference in society-environmental change research     

《Global Environmental Change》2022

In light of the challenges posed by contemporary environmental changes, interest in past environmental impacts and societies’ responses to them is burgeoning. The main strength of such research lies in its ability to analyze completed society-environment interactions. Scholars have argued that such analyses can improve our understanding of present challenges and offer useful lessons to guide adaptation responses. Yet despite considerable differences between past and present societies, our inherently limited knowledge of the past and our changing understanding of it, much of this research uses historical antecedents uncritically, assuming that past societal impacts and responses are directly analogous to contemporary ones. We argue that this approach is unsound both methodologically and theoretically, thus drawing insights that might offer an erroneous course of action.To illustrate the challenges in drawing historical analogies, we outline several fundamental differences between past and present societies as well as broader limitations of historical research. Based on these points, we argue that scholars who apply historical inference in their work should do so critically, while reflecting on the objectives of learning from the past and the limitations of this process. We suggest a number of ways to improve past-present analogies, such as defining more explicitly what we can learn from the past, clarifying the rationale for using the analogy, and reducing the number of variables compared between past and present.  相似文献   

Are managed retreat programs successful and just? A global mapping of success typologies,justice dimensions,and trade-offs     

《Global Environmental Change》2022

As managed retreat programs expand across the globe, there is an urgent need to assess whether these programs are reducing exposure to climatic hazards, enhancing adaptive capacity, and improving the living conditions of communities in a just and equitable manner or are they exacerbating existing risks and vulnerabilities? Strictly speaking, are retreat programs successful? Using an expansive intersectional justice approach to examine 138 post-resettlement case studies published between 2000 and 2021 across the Global North and South, we identified five typologies of success – techno-managerial, eco-restorative, compensatory, reformative, and transformative – and their trade-offs and synergies. Our meta-analysis incorporated a variety of metrics: relocation types, funding, decision making, socio-economic class, land use change, livelihood options, and social impacts. We found 26% of cases failed, 43% were successful, and 30% are on-going and therefore success was undetermined. The techno-managerial cases, while successful in the limited terms of relocating residents, paid little attention to equity and justice. The eco-restorative and compensatory cases reduced hazard exposure but revealed the synergies and tensions associated with social, ecological, and intergenerational justice. The reformative and transformative cases improved community wellbeing, rootedness, and access to livelihoods while incorporating diverse justice concerns to different degrees. By intersecting these typologies with multiple dimensions of justice, this study advances a novel planning and analytical tool for assessing the potential success or failure of current and future retreat programs.  相似文献