Dissolved and particulate trace metal fluxes through the central English Channel, and the influence of coastal gyres     

P. J. Statham  S. Leclercq  V. Hart  M. Batt  Y. Auger  M. Wartel  J. Cheftel 《Continental Shelf Research》1999,19(15-16)

Measurements of dissolved Cd, Co, Cu, Mn, Ni, Pb, and Zn have been made on a seasonal basis at five stations on a north–south transect across the central English Channel between Cherbourg and the Isle of Wight. Vertical and horizontal distributions of dissolved Cd, Pb, Cu and Zn are relatively uniform except for sampling sites near the English coast. Dissolved Mn and Co show increased concentrations in the English coastal waters, and for Mn the seasonal trend in concentration follows the pattern seen in the Strait of Dover with higher values in the late summer. Ni and Cu are higher in concentration on the English side, which reflects mainly riverine sources. Measurements were also made of particulate forms of the metals above plus particulate Al, Ca, Fe, Mg, Sr and Ti. Water column concentrations of particulate metals broadly follow the distribution of suspended particulate matter, with highest concentrations near the UK coast. Trace metal concentrations have been integrated with modelled data on fluxes of water to provide estimates of fluxes for these elements into the eastern Channel, and an initial comparison is made with data for fluxes of metals through the Strait of Dover obtained during an earlier study. A major influence on the fluxes of particulate metals through the Isle of Wight-Cherbourg transect is the gyre system to the South east to the Isle of Wight, which has important east to west as well as west to east transport components. For those elements where the dissolved form of the metal dominates, the large flow of water in the central Channel waters leads to major fluxes of the metals towards the east and the Strait of Dover. However, the high suspended particulate matter loadings in the coastal waters and impact of the gyre system lead to net east to west fluxes of particulate Al, Fe, Mn and Ti. Comparison of these fluxes with data on the net west to east transport of these materials through the Strait of Dover infers that there must be a significant supply of these particulate metals to the eastern Channel.  相似文献   

Integration of natural data within a numerical model of ablative subduction: a possible interpretation for the Alpine dynamics of the Austroalpine crust     

M. RODA  M. I. SPALLA  A. M. MAROTTA 《Journal of Metamorphic Geology》2012,30(9):973-996

A numerical modelling approach is used to validate the physical and geological reliability of the ablative subduction mechanism during Alpine convergence in order to interpret the tectonic and metamorphic evolution of an inner portion of the Alpine belt: the Austroalpine Domain. The model predictions and the natural data for the Austroalpine of the Western Alps agree very well in terms of P–T peak conditions, relative chronology of peak and exhumation events, P–T–t paths, thermal gradients and the tectonic evolution of the continental rocks. These findings suggest that a pre‐collisional evolution of this domain, with the burial of the continental rocks (induced by ablative subduction of the overriding Adria plate) and their exhumation (driven by an upwelling flow generated in a hydrated mantle wedge) could be a valid mechanism that reproduces the actual tectono‐metamorphic configuration of this part of the Alps. There is less agreement between the model predictions and the natural data for the Austroalpine of the Central‐Eastern Alps. Based on the natural data available in the literature, a critical discussion of the other proposed mechanisms is presented, and additional geological factors that should be considered within the numerical model are suggested to improve the fitting to the numerical results; these factors include variations in the continental and/or oceanic thickness, variation of the subduction rate and/or slab dip, the initial thermal state of the passive margin, the occurrence of continental collision and an oblique convergence.  相似文献   

欧洲地震委员会第24届大会综述     

朱传镇  傅征祥 《国际地震动态》1995,(2):18-22

欧洲地震委员会第２４届大会于１９９４年９月１９－２４日在希腊首都雅典召开，出席这次大会的代表共３８０人。会上宣读和张贴论文５４１篇，内容主要涉及地震预测研究、地震活动性、工程地震、震源物理和数据采集、理论与解释等。本文综述这次大会的情况。  相似文献   

中国—欧洲共同体地震科学合作项目“北京西北延庆—怀来盆地地震学研究”进展     

王培德  王鸣  任道容  田玉红  张廉强  汪更滋  陈运泰 《地震地磁观测与研究》1995,(6)

为探索强烈地震的前兆，在欧洲共同体的支持下，中国和英国的地震学家共同在北京西北的延庆—怀来盆地建立了一个数字地震台网．延庆—怀来数字地震台网由５个野外台和一个中心台构成。研究工作的重点是探索强烈地震前地震横波分裂现象中的参数变化．１９９５年４月３０日台网建成并投入运作．１９９５年７月下旬．怀来地区发生ＭＬ＝４．０地震及其余震，延庆—怀来数字地震台网很好地记录了这一地震序列。初步的分析表明．这一地震序列表明了怀来县城以南６—８ｋｍ处，怀来盆地南缘下部的断层活动，它与怀来地区地表有明显出露的主要断裂没有明显的直接联系。  相似文献   

新疆及其邻区的地震窗前兆与短期地震预报   总被引：2，自引：0，他引：2  

敖雪明  王桂岭 《内陆地震》1993,7(2):121-127

根据新疆及毗邻的独联体部分国家区域台网微震观测记录,通过普查与统计检验,筛选出22个具有较高短期预报效能的地震窗。较系统地研究了地震窗小震月频度的前兆特征及其用于短期地震预报的判据指标,着重介绍了近两年新疆与独联体科技合作的最新成果,同时给出若干成功预报震例,并对所得结果的可能物理机制等问题进行了讨论。  相似文献   

Beltanelloides podolicus 在中国上震旦统首次发现   总被引：8，自引：0，他引：8       下载免费PDF全文

陈孟莪  萧宗正  袁训来 《地质科学》1993,(4):312-316

Beltanelloidespodolicus可谓球形藻群体化石之最大者,压扁圆盘体直径3-30mm,呈炭质膜保存。与其一起出现的化石还有许多高级藻类和动物化石。它们的发现为扬子地台上震旦统与东欧地台文德期地层的对比又添一证据。  相似文献   

Green hope or greenwash? The actions of the European Union at the World Summit on sustainable development     

Simon Lightfoot  Jon Burchell   《Global Environmental Change》2004,14(4):73

This article examines whether the European Union (EU) could be seen as a normative power at the recent World Summit on Sustainable Development. We explain how the EU operationalised its commitment to the concept of sustainable development before highlighting the impact the EU had on the final summit outcomes. It shows that although in many areas the EU was able to offer leadership, internal policy coherence prevented it fully being able to develop that role and thus fully promoting the norm of sustainable development.  相似文献   

Combining field and modelling techniques to assess rockfall dynamics on a protection forest hillslope in the European Alps   总被引：4，自引：0，他引：4  

Luuk K. A. Dorren  Bernhard Maier  Uif S. Putters  Arie C. Seijmonsbergen 《Geomorphology》2004,57(3-4):151-167

Adequate management of a mountain forest that protects downslope areas against impacts of rockfall requires insight into the dynamics of the hillslope environment. Therefore, we applied a combined approach, using field and modelling techniques, to assess the determining factors for rockfall source areas, rockfall tracks and rockfall runout zones on a forested slope in mountainous terrain. The first objective of this study was to understand why rockfall occurs in the study area. The second objective was to translate the knowledge obtained in the field into a model that simulates rockfall dynamics on a forested slope realistically. The third objective was to assess which hillslope characteristics primarily determine the distribution of active rockfall tracks. To achieve these objectives, we made a geomorphological map of the whole study area, and we measured the major discontinuity planes in the bedrock that are exposed in the rockfall source areas. Furthermore, a test site for simulation modelling within the larger study area was defined in which both a forest and a hillslope inventory were carried out. The available data and our developed rockfall simulation model allowed us to assess the slope characteristics that mainly determine the distribution of areas affected by rockfall. We found that in decreasing order of importance, both standing and felled trees, the surface roughness and rockfall resistant shrubs primarily determine the distribution of rockfall-affected areas. Simulation tests without a forest cover produced similar rockfall runout zones as fossil rockfall events identified in the field. We believe that the combined field and modelling approach is a prerequisite for understanding how forests can protect against rockfall.  相似文献   

New approaches to integrated quality assessment of lakeshores     

Wolfgang Ostendorp   《Limnologica》2004,34(1-2):160

The EU Water Framework Directive (WFD) requires the ecological assessment of water bodies. Since the littoral zones and the lakeshores are part of lakes as water bodies as defined by the WFD, a new scheme for ecological quality assessment of lakeshores should be established. It is proposed that this scheme should go beyond the formal requirements of the WFD, as it includes aspects of nature conservancy, landscape protection, and regional planning and development. Some of these aspects are subject to other EU legislation (e.g. Habitats Directive) and some are subject to national legislation. Ten general Quality Elements (QEs) are proposed, which can be refined and reified through several levels of detail, depending on the specific aims of a study. A list of eleven topics, which should be discussed in the establishment of the lakeshore quality assessment scheme, is given. The more complex ones are the implementation of other EU legislation, the definition of lakeshore types and reference conditions, the stipulation of best aggregation procedures, and a better understanding of the significance of hydrological and morphological impacts on the biota.  相似文献   

The Glueckstadt Graben, a sedimentary record between the North and Baltic Sea in north Central Europe   总被引：2，自引：1，他引：2  

Yuriy Maystrenko  Ulf Bayer  Magdalena Scheck-Wenderoth 《Tectonophysics》2005,397(1-2):113

The Glueckstadt Graben is one of the deepest post-Permian structures within the Central European Basin system and is located right at its “heart” at the transition from the North Sea to the Baltic Sea and from the Lower Saxony Basin to the Rynkoebing–Fyn High.The Mesozoic to recent evolution is investigated by use of selected seismic lines, seismic flattening and a 3D structural model. A major tectonic event in the latest Middle–Late Triassic (Keuper) was accompanied by strong salt tectonics within the Glueckstadt Graben. At that time, a rapid subsidence took place within the central part, which provides the “core” of the Glueckstadt Graben. The post-Triassic tectonic evolution of the area does not follow the typical scheme of thermal subsidence. In contrast, it seems that there is a slow progressive activation of salt movements triggered by the initial Triassic event. Starting with the Jurassic, the subsidence centre partitioned into two parts located adjacent to the Triassic “core.” In comparison with other areas of the Central European Basin system, the Glueckstadt Graben was not strongly affected by additional Jurassic and Cretaceous events. During the late Jurassic to Early Cretaceous, the area around the Glueckstadt Graben was affected by relative uplift with regional erosion of the elevated relief. However, subsidence was reactivated and accelerated during the Cenozoic when a strong subsidence centre developed in the North Sea. During Paleogene and Quaternary–Neogene, the two centres of sedimentation moved gradually towards the flanks of the basin.The data indeed point toward a control of post-Permian evolution by gradual withdrawal of salt triggered by the initial exhaustion along the Triassic subsidence centre. In this sense, the Glueckstadt Graben was formed at least partially as “basin scale rim syncline” during post-Permian times. The present day Hamburger, East and Westholstein Troughs are the actual final state of this long-term process which still may continue and may play a role in terms of young processes and, e.g., for coastal protection.  相似文献