Evaluation of stakeholder perspectives on the management of the stalked barnacles (Pollicipes pollicipes) resource in the Parque Natural do Sudoeste Alentejano e Costa Vicentina,Portugal     

《Marine Policy》2014

The stalked barnacle, <em>Pollicipes pollicipesem>, is a shellfish resource which has been traditionally harvested by the coastal communities of the Iberian Peninsula. However, in recent years <em>Pollicipesem> has attracted increased harvesting pressure due to its high market value. In a national park on the south-western coast of Portugal, legislation was formulated to address the overharvesting of this resource; however, its success has been limited due to lack of consensus among stakeholders. A Systems Approach Framework (SAF) was used to assess the socio-economic and cultural issues surrounding the harvest of <em>Pollicipesem>. As part of this, interviews and a questionnaire survey were undertaken in the municipality of Vila do Bispo, in order to explore the perspectives of the shell fishers, local residents and restaurateurs. The majority of the stakeholders believed that the resource was overharvested and that their needs should be considered as part of the legislation formulation process. The stakeholders also agreed that the local market should be re-established and that the temporal closure period should be reconsidered. Stakeholder opinions differed with regard to the level of coastal management enforcement required, the licence distribution process and the restrictions implemented by national park authorities. It is concluded that using information such as that gathered from local stakeholders, it should be possible to effectively extend the SAF to simulate scenarios for future management options.  相似文献   

Rapid Determination of Trace and Ultra Trace Level Elements in Diverse Silicate Rocks in Pressed Powder Pellet Targets by LA‐ICP‐MS using a Matrix‐Independent Protocol     

Pulok K. Mukherjee  Param P. Khanna  Naresh K. Saini 《Geostandards and Geoanalytical Research》2014,38(3):363-379

A simple, single sample preparation involving pressed rock powder pellets was utilised to determine the trace and ultra trace abundances of petrogenetically important elements including high field‐strength elements and REEs by laser ablation‐ICP‐MS. One of the elements predetermined by XRF spectrometry served as an internal standard. The influence of sample preparation parameters (grain size, pellet compactness and amount of binding media) on analytical performance was also investigated, including sample homogeneity issues at the laser sampling scale. Line scanning with a high repetition frequency (20 Hz) and large beam diameter (200 μm) ensured ablation from a larger sample surface area, eliminating issues related to sample heterogeneity. A median grain size of about 10 μm for silicate rock powders was found to be sufficiently representative at this scale of laser sampling. Granitic rocks or samples containing resistant minerals such as zircon needed extra grinding to achieve grain sizes down to < 5 μm for better precision for elements that are concentrated in these phases. Using ¹³⁷Ba as an internal standard, reasonable accuracies within 15–20% for most of the high mass trace elements were achieved; in the case of low mass elements, it may deviate up to 40%. Precision of measurements rarely exceeded 15% RSD.  相似文献   

Towards a Higher Comparability of Geothermometric Data obtained by Raman Spectroscopy of Carbonaceous Material. Part I: Evaluation of Biasing Factors   总被引：1，自引：0，他引：1  

Nils K. Lünsdorf  Istvan Dunkl  Burkhard C. Schmidt  Gerd Rantitsch  Hilmar von Eynatten 《Geostandards and Geoanalytical Research》2014,38(1):73-94

Raman spectroscopy of carbonaceous material (RSCM) is frequently used to determine metamorphic peak temperatures from the structural order of carbonaceous material enclosed in metasediments. This method provides a quick, robust and relatively cheap geothermometer. However, the comparability of the RSCM parameter is low as there are at least three major sources of biasing factors. These sources are the spectral curve‐fitting procedure, the sample characteristics itself and the experimental design including the used Raman system. To assess the impacts of the biasing factors on RSCM, a series of experiments was performed. The experiments showed that curve‐fitting is strongly influenced by individual operator‐bias and the degrees of freedom in the model, implying the need for a standardised curve‐fitting procedure. Due to the diversity of components (optics, light detection device, gratings, etc.) and their combinations within the Raman systems, different Raman instruments generally give differing results. Consequently, to estimate comparable metamorphic temperatures from RSCM data, every Raman instrument needs its own calibration. This demands a reference material series that covers the entire temperature calibration range. Although sample heterogeneity will still induce some variation, a reference material series combined with standardised curve‐fitting procedures will significantly increase the overall comparability of RSCM data from different laboratories.  相似文献   

Upper Cretaceous amber from Vendée,north-western France: Age dating and geological,chemical, and palaeontological characteristics     

《Cretaceous Research》2017

The Upper Cretaceous lignite deposits of La Garnache, Vendée (north-western France), consist of two lignitic clay series, Garnache 1 and Garnache 2, separated by a fault. The first series cropped out to the south of the fault during road works until 2002 but is now covered by an embankment. It has provided numerous pieces of amber containing arthropod and micro-organism inclusions. The second lignitic series, exposed to the north of the fault, is rich in fossil wood but devoid of amber. Palynological analysis of Garnache 1 revealed several Normapolles species belonging to the genera <em>Atlantopollisem>, <em>Complexiopollisem>, <em>Osculapollisem>, <em>Plicapollisem> and <em>Trudopollisem>, but larger forms typical of Senonian deposits are absent. By contrast, Garnache 2 proved to be dominated taxonomically and numerically by spores (<em>Appendicisporitesem>, <em>Camarozonosporitesem>, <em>Gleicheniiditesem>, <em>Patellasporitesem>, <em>Stereisporitesem>), associated with a few gymnosperm (<em>Cerebropollenitesem>, <em>Phyllocladiditesem>, <em>Classopollisem>) and angiosperm (<em>Liliaciditesem>, <em>Retitricolpitesem> and a single specimen of the Normapolles <em>Complexiopollisem>) taxa. Garnache 1 is, therefore, younger than Garnache 2, the latter being clearly Cenomanian in age whereas Garnache 1 is more likely to be Turonian. Lignitic clay of Garnache 1 contains numerous translucent, orange to red, pieces of amber. Vendean amber is rich in aquatic arthropods, such as tanaids and epicarideans (Crustacea), as well as marine or brackish siliceous micro-organisms such as diatoms and sponge spicules. These aquatic inclusions indicate that resin-producing trees grew along and close to the seashore. The amber-bearing clay was deposited in a calm, estuarine or lagoonal, muddy environment.  相似文献   

冰塞下冰块起动分析   总被引：2，自引：0，他引：2  

王军 《水文》1999,(2)

对冰塞下冰块临界起动条件进行了分析研究,指出了过去研究的缺陷是与实际情况吻合较差以及计算公式构造不合理有关。根据有关理论分析与推导,提出了冰塞下冰块临界起动计算公式应具有的合理形式。并就部分因子进行了试验研究,研究结果表明,在不考虑ｔｂ／Ｌ和ｎｉ／ｎｂ变化的情况下,冰塞下冰块起动流速和泥沙起动流速的计算公式具有相同的形式。  相似文献   

评估灌注桩极限承载力的概率能量法     

娄仲连  罗国煜 《高校地质学报》1998,4(4):452-458

本文研究用概率能量方法评估灌注桩极限承载力的可行性,研究所用数据取自南京市区的２００根桩例的ＣＡＰＷＡＰ反分析与静载试验结果。根据能量守恒定律并结合动态桩－土相互作用模型,详细地推导了桩极限承载力计算公式。并对其中的模型参数,Ｊｓ,Ｊｔ,Ｑｓ,Ｑｔ作为随机变量处理,统计分析了它们的平均值,标准差以及概率分布函数。用蒙特卡洛法模拟确定了桩极限承载力的概率分布函数,并进一步提出了计算桩极限承载力超过某一设计值的概率公式。通过计算的桩极限承载力与静载结果的良好可比性,说明了此方法的台理性与准确性。  相似文献   

裂隙介质电性各向异性的研究     

石雅镠  宁书年  宁静 《煤田地质与勘探》2005,33(2):65-67

文中提出了一个一般介质的裂隙集中体积模型,由此导出了裂隙介质以及作为特例的EDA介质的各向异性电导率表达式。然后,从大地电磁测深法的角度,详细地推导了双层地层 (含裂隙)结构的视电阻率正演公式。最后,利用所得结果进行了数值模拟。本文的结果有助于进一步开展电性各向异性及其与地震的联合解释的研究。   相似文献   

论太湖平原洪涝灾害与水利工程问题和发展趋势   总被引：5，自引：1，他引：4  

陈西庆  陈吉余 《湖泊科学》1994,6(4):364-374

在分析研究太湖流域洪涝灾害成因及以围圩、筑堤、建闸为特点的圩区经济基础上,论述了近几十年来流域下垫面变化对流域水情的影响。总结了近40年来流域水利工程规划设计的经验与不足之处;展望了未来几十年流域水情变化发展趋势,特别是全球海平面上升对流域洪水蓄、泄方面的重大影响。指出在流域十大骨干水利工程的基础上,今后流域中新建骨干工程的关键目标是提高长江南岸、杭州湾北岸闭闸时段的排洪能力及建设吴淞挡潮闸,从而大幅度提高各潮周期内黄浦江净泄洪量;同时运用非工程措施,确保与充分利用区内洪水调蓄能力。  相似文献   

利用²¹⁰Pb、¹³⁷Cs和²⁴¹Am计年法测算云南抚仙湖现代沉积速率   总被引：6，自引：0，他引：6  

王小雷  杨浩  赵其国  魏荣菲 《湖泊科学》2010,22(1):136-142

通过对云南抚仙湖沉积物柱芯样品的210Pb、137Cs和241Am测试表明,柱芯剖面上有明显的1963年和1986年137Cs蓄积峰,验证了1975年次级蓄积峰存在的可能性,这些峰形完好的蓄积峰对抚仙湖的现代沉积环境有明显的时标意义。利用137Cs计年法得到抚仙湖沉积物自1963年、1975年及1986年以来到2007年的平均沉积速率分别为0.063g/(cm2·a)、0.052g/(cm2·a)和0.039g/(cm2·a),说明了过去近五十年抚仙湖沉积速率整体上经历了一个由快到慢的过程。借助于241Am 的1963年蓄积峰可以提高137Cs计年的准确性。根据210PbCRS计年模式,计算出每个样品深度所对应的年代,与137Cs计年法比较存在一定的偏差,分析了两种计年方法存在差异性的原因。通过质量深度和年代分析,抚仙湖的沉积速率变化幅度比较大,表明抚仙湖近129年来的沉积环境不稳定,可能与相应历史时期的人类活动有密切的关系。  相似文献   

Scientific detector workshop 2022 on-sky performance verification of near-infrared e−APD technology for wavefront sensing and demonstration of e−APD pixel performance to improve the sensitivity of large science focal planes     

Gert Finger  Frank Eisenhauer  Reinhard Genzel  Christopher Mandla  Ian Baker  Domingo Alvarez  Antonio Amorim  Wolfgang Brandner  Christophe Dupuy  Casey Deen  Derek Ives  Leander Mehrgan  Manfred Meyer  Karin Perraut  Guy Perrin  Jörg Stegmeier  Christian Straubmeier  Harald J. Weller  Vincent Isgar 《Astronomische Nachrichten》2023,344(8-9):e20230069

Near-infrared adaptive optics as well as fringe tracking for coherent beam combination in optical interferometry require the development of high-speed sensors. Because of the high speed, a large analog bandwidth is required. The short exposure times result in small signal levels which require noiseless detection. Both requirements cannot be met by state-of-the-art conventional CMOS technology of near-infrared arrays as has been attempted previously. A total of five near-infrared SAPHIRA 320 × 256 pixel HgCdTe e⁻APD arrays have been deployed in the wavefront sensors and in the fringe tracker of the VLTI instrument GRAVITY. The current limiting magnitude for coherent exposures with GRAVITY is m_k = 19, which is made possible with ADP technology. New avalanche photo-diode array (APD) developments since GRAVITY include the extension of the spectral sensitivity to the wavelength range from 0.8 to 2.5 μm. After GRAVITY a larger format array with 512 × 512 pixels has been developed for both AO applications at the ELT and for long integration times. Since dark currents of <10⁻³ e⁻/s have been demonstrated with 1Kx1K e⁻APD arrays and 2Kx2K e⁻APD arrays have already been developed, the possibilities and adaptations of e⁻APD technology to provide noiseless large-format science-grade arrays for long integration times are also discussed.  相似文献