Diatom‐based tidal‐level transfer functions as an aid in reconstructing Quaternary history of sea‐level movements in the UK     

Yongqiang Zong  Benjamin P. Horton 《第四纪科学杂志》1999,14(2):153-167

This research analyses the diatom asssemblages recorded from six UK coastal sites and relates these diatom assemblages to tidal levels. The relationship between diatom assemblages and tidal levels is examined statistically in order to develop a diatom‐based tidal‐level transfer function. The results suggest that there is highly significant correlation between the diatom assemblages and water levels from mean high water of neap tides to highest astronomical tide (p = 0.01, 99 random permutations). A weighted average (WA) transfer function is thus established, and the predictive ability of this transfer function is highly satisfactory. Finally, this transfer function is applied successfully to estimate palaeotidal‐levels from fossil diatom data recorded in late Holocene coastal sequences. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献   

山东省城乡发展协调性空间差异分析   总被引：10，自引：2，他引：8  

王富喜  孙海燕  孙峰华 《地理科学》2009,29(3)

遵循全面性、主导性、可比性及可获得性原则,构建了城乡发展协调性评价指标体系,运用主成分分析方法分别计算出山东省17地市城市子系统和农村子系统的综合发展指数。在此基础上,通过城乡协调度系数对各地市城乡发展协调性进行了分析评价。结果表明:①山东省城乡发展协调性空间差异非常明显,总体而言,东部地区好于中西部地区。②城乡协调度与经济发展水平总体呈正相关,经济发展水平越高,城乡发展协调性越好。③协调是个相对、动态的概念,城乡协调发展亦没有绝对的标准,同样的协调度反映的信息不一定相同。  相似文献   

Yanshanian Magma-Tectonic-Metallogenic Belt in East China of Circum-Pacific Domain (Ⅱ): Lithosphere-Asthenosphere System and Metallogenic Environment     

Deng Jinfu Mo Xuanxue Zhao Hailing Luo Zhaohua Dai Shengqian Department of Geology  Mineral Resources  China University of Geosciences  Beijing 《中国地质大学学报(英文版)》1999,10(1)

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Rehabilitation of Saline Wetlands, Olympics 2000 Site, Sydney (Australia)—I: Management Strategies Based on Ecological Needs Assessment     

M. D. Burchett  A. Pulkownik  C. Grant  G. Macfarlane 《Marine pollution bulletin》1999,37(8-12):515-525

The Homebush Bay area, Sydney, site of the Olympic Games 2000, has been largely occupied for nearly a century by an abattoir, brickworks, armaments depot and waste dumps. However, it contains remnants of original ecosystems, including two estuarine wetlands, and the Olympic Co-ordination Authority (OCA), set up to manage the redevelopment of the site, is committed to the rehabilitation of these ecosystems. The ecological approaches and rehabilitation measures used for one of the wetlands are detailed. Apart from a history of disturbance, it has for 10 years been without tidal flushing. However, these wetlands are the largest remaining in the Sydney estuary, and are significant for a number of reasons including biodiversity and waterbird conservation. The ecological parameters of the site, the results of a ‘before-restoration-impact' study, and the iterative links between science and management in the introduction of the rehabilitation measures, are presented. Criteria for success are discussed, along with biomonitoring strategies to test success.  相似文献   

Celestial n-Body Coupling in the Lunar Orbit Theory     

K. H. Tsui 《Celestial Mechanics and Dynamical Astronomy》2000,77(2):93-105

Making use of the fact that, in the solar system, the angular momentum is carried predominantly by the planets while the mass is beared almost entirely by the Sun, an iterative scheme is devised to solve approximately the n-body contributions of the lunar orbit problem. The scheme envisages the Moon-Earth-Sun three-body subsystem as being nested in the grand Earth-Jupiter-Sun system. In the planetocentric representation, the orbital motion of the Sun about the solar system center of mass is transmitted to the third body via the second primary body in both the grand and nested three-body systems. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

MAPGIS库管理子系统的运用方法及其意义     

张艳玲  叶萍  王国良 《吉林地质》2000,19(3):71-73,82

本文通过应用ＭＡＰＧＩＳ软件的实践,初步总结出其库管理子系统的运用方法,主要谈及以下三方面的问题：１．建库;２．图幅接边;３．图幅的检索输出。作者以１：５万地质图数据库为例,讨论了１：５万数据库的基础性,现实性以及重要性。  相似文献   

Combined effects of waves and plants on a mud deposition event at a mudflat-saltmarsh edge in the Bahía Blanca estuary     

Paula D. Pratolongo  Gerardo M.E. Perillo  M. Cintia Piccolo 《Estuarine, Coastal and Shelf Science》2010

This study was carried out at the Bahía Blanca Estuary, Argentina, at the seaward edge of a saltmarsh. The saltmarsh-mudflat boundary in the study area shows sediment deposits at a higher elevation immediately seaward of the saltmarsh edge. We compared field determinations of water velocity, bed shear stress, wind wave conditions and variations of the bed elevation in the mudflat and within the Spartina alterniflora canopy at the seaward edge of a saltmarsh, and we evaluated the relative role of vegetation in the observed morphology. A mud deposition event that raised bed elevation in more than 5 cm occurred during the study period, with TSS concentrations > 500 mg l⁻¹, but simultaneous measurements performed on the bed levels confirmed that the sediments deposited did not originate from local resuspension within the edge of the canopy. In similar tidal cycles in terms of local wave activity and bed shear stresses at the sampling site, deposition occurred only with winds aligned with the azimuth of the Canal Principal, reaching a maximum fetch of more than 20 km in front of the sampling site.  相似文献   

Surface evolution and carbon sequestration in disturbed and undisturbed wetland soils of the Hunter estuary,southeast Australia   总被引：2，自引：0，他引：2  

A.J. Howe  J.F. Rodríguez  P.M. Saco 《Estuarine, Coastal and Shelf Science》2009

The aim of this work was to quantify the soil carbon storage and sequestration rates of undisturbed natural wetlands and disturbed wetlands subject to restriction of tidal flow and subsequent rehabilitation in an Australian estuary. Disturbed and undisturbed estuarine wetlands of the Hunter estuary, New South Wales, Australia were selected as the study sites for this research. Vertical accretion rates of estuarine substrates were combined with soil carbon concentrations and bulk densities to determine the carbon store and carbon sequestration rates of the substrates tested. Relationships between estuary water level, soil evolution and vertical accretion were also examined. The carbon sequestration rate of undisturbed wetlands was lower (15% for mangrove and 55% for saltmarsh) than disturbed wetlands, but the carbon store was higher (65% for mangrove and 60% for saltmarsh). The increased carbon sequestration rate of the disturbed wetlands was driven by substantially higher rates of vertical accretion (95% for mangrove and 345% for saltmarsh). Estuarine wetland carbon stores were estimated at 700–1000 Gg C for the Hunter estuary and 3900–5600 Gg C for New South Wales. Vertical accretion and carbon sequestration rates of estuarine wetlands in the Hunter are at the lower end of the range reported in the literature. The comparatively high carbon sequestration rates reported for the disturbed wetlands in this study indicate that wetland rehabilitation has positive benefits for regulation of atmospheric carbon concentrations, in addition to more broadly accepted ecosystem services.  相似文献   

A cellular automata model for population expansion of Spartina alterniflora at Jiuduansha Shoals,Shanghai, China     

Hua-mei Huang  Li-quan ZhangYu-juan Guan  Dong-hui Wang 《Estuarine, Coastal and Shelf Science》2008

Biological invasion has received considerable attention recently because of increasing impacts on local ecosystems. Expansion of Spartina alterniflora, a non-native species, on the intertidal mudflats of Jiuduansha Shoals at the Yangtze River Estuary is a prime example of a spatially-structured invasion in a relatively simple habitat, for which strategic control efforts can be modeled and applied. Here, we developed a Cellular Automata (CA) model, in conjunction with Remote Sensing and Geographical Information Systems, to simulate the expanding process of S. alterniflora for a period of 8 years after being introduced to the new shoals, and to study the interactions between spatial pattern and ecosystem processes for the saltmarsh vegetation. The results showed that the CA model could simulate the population dynamics of S. alterniflora and Phragmites australis on the Jiuduansha Shoals successfully. The results strongly support the hypothesis of space pre-emption as well as range expansion with simple advancing wave fronts for these two species. In the Yangtze River Estuary, the native species P. australis shares the same niche with the exotic species S. alterniflora. However, the range expansion rate of P. australis was much slower than that of S. alterniflora. With the accretion of the Jiuduansha Shoals due to the large quantity of sediments deposited by the Yangtze River, a rapid range expansion of S. alterniflora is predicted to last for a long period into future. This study indicated the potential for this approach to provide valuable insights into population and community ecology of invasive species, which could be very important for wetland biodiversity conservation and resource management in the Yangtze River Estuary and other such impacted areas.  相似文献   

地震观测标准子体系研究   总被引：2，自引：0，他引：2  

冯义钧  赵家骝 《地震地磁观测与研究》2005,26(1):78-84

根据《地震行业标准体系表》(DB／T1-2000)和2002年及2004年国家科技部项目《数字化地震前兆观测技术标准》实施过程中得到的认识,运用标准体系的原理和建立标准体系的原则与方法,研究和分析了地震观测标准子体系的结构和层次划分以及地震观测专业通用标准和地震观测门类通用标准,为进一步修订地震行业标准体系表提出了建议性的结论。  相似文献