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471.
472.
Fulton Elizabeth A.; Smith Anthony D.M.; Punt Andre E. 《ICES Journal of Marine Science》2005,62(3):540-551
473.
Livingston P.A.; Aydin K.; Boldt J.; Ianelli J.; Jurado-Molina J. 《ICES Journal of Marine Science》2005,62(3):592-597
474.
北京十三陵中元古界长城系沉积相标志及沉积环境演化模式 总被引:9,自引:6,他引:9
北京十三陵地区中元古界长城系包括5个组:常州沟组、串岭沟组、团山子组、大红峪组、高于庄组,前2个组主要由碎屑岩组成,后3个组主要由碳酸盐岩组成。众多的沉积相标志从不同侧面说明:常州沟组沉积属于滨浅海碎屑岩沉积环境;从串岭沟组开始,其沉积环境向碳酸盐岩沉积环境过渡;后3个组沉积时的环境为典型的陆表海碳酸盐岩沉积环境。在综合研究的基础上给出了沉积环境演化模式。另外,长城系还有许多特殊的沉积现象值得进一步研究和讨论:世界上最古老的宇宙球粒;高于庄组白云岩层面上双脊波痕的内碎屑颗粒成因和硅化白云岩内青鱼骨状层理及硅质团粒的成因;特别是在大红峪组首次发现太阳星云物质-碳质球粒陨石。 相似文献
475.
对研究区成矿物质来源、成矿物理化学条件、成矿地质条件以及找矿标志进行了研究和探讨。为该区的地质找矿提出了依据和方向。 相似文献
476.
477.
Arthur Conacher 《The Australian geographer》1998,29(2):175-189
Environmental or land quality indicators are being developed internationally as a means whereby the ‘State of the Environment’ (SoE) can be assessed and trends monitored. In Australia, the use of indicators in SoE reporting is in its early stages of development. Indicators have been developed, in relation to agriculture, for flora and fauna, soil, chemical contamination, surface waters and groundwater. Internationally, the World Bank has listed ‘indicators of pressure’ on the land, ‘indicators of state and impact’, and ‘indicators of response’ for each of seven major issues of land degradation. Late in 1996, an ‘indicators of catchment health’ workshop in Australia identified a relatively small number of key indicators relating to farm productivity, soil health, water quality and ‘landscape integrity’, later adding social indicators, and also distinguishing between indicators at farm and catchment scales. A broad range of other indicators was also considered by various participants in the workshop, which concluded by supporting a nationally co‐ordinated effort and the establishment of a national steering committee. Although most indicators are static measures, those from which predictions can be made require a greater emphasis on the functioning of the system. This implies that indicators are only one aspect of system modelling, and that environmental or land assessment needs to progress further than the search for quality indicators. Since this involves both biophysical and human processes, geographers should be playing a central role. 相似文献
478.
The present communication addresses the potential use of damage features, observed in the ancient ruins of the Avdat archeological
site (Negev Desert, Israel) as a tool to identify the seismic origin of the destruction there and roughly to determine the
direction of seismic wave propagation.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
479.
Antonella Cattaneo Yves Couillard Sybille Wunsam Michel Courcelles 《Journal of Paleolimnology》2004,32(2):163-175
We studied diatom taxonomic composition and the presence of morphological alterations (size and deformations) along a sediment core collected in Lac Dufault, Abitibi, whose watershed has a long history of mining pollution presently undergoing mitigation. According to sediment dating with 210Pb and metal profiles along the core, we could identify four periods in the contamination history of the lake, which were characterized by different diatoms. Tabellaria flocculosa was dominant in the pre-mining period but was drastically reduced at the onset of pollution when Fragilaria cf. tenera became important. This diatom, together with other Fragilaria species and cysts of Chaetoceros muelleri, typified the transition period in which Cu reached its maximum value and other metals started to increase. During the period of maximum contamination with Zn, Cd, and Fe accompanied by acid mine drainage, Achnanthes minutissima and Brachysira vitrea were dominant. These taxa started to wane in the most recent sediments representing a partial chemical recovery. Asterionella formosa, which almost vanished at mining onset, reappeared with high abundance in these superficial sections. Beside these taxonomical shifts, we observed during the contamination period significant reduction in valve length together with increased percentages of valve deformations. Because available data on water chemistry and a diatom-based pH reconstruction suggest that Lac Dufault escaped severe acidification, diatom patterns observed in the core can be mostly ascribed to metal contamination. Individual diatom abundance and valve length had strong statistical relationships with the different metals identified in the core. Diatom changes both taxonomic and morphological can be excellent specific indicator of metal contamination and early recovery. 相似文献
480.
中国环境-健康区域综合评价 总被引:1,自引:0,他引:1
The aim of the study was to assess the environment-health development in different regions of China. 175 indicators, such as average life expectancy at birth, emission intensity of waste gas, GDP etc. were chosen to describe various aspects of the environment, health and development of China. Of all the indicators, life expectancy can sufficiently reflect health situation of population. Consequently,life expectancy was identified as key indicator, and 42 out of 175 indicators were selected for establishing the environment-health indicator fiamework with three grades of integrative indices to assess the development of environment-health of China. Based on the hierarchical relation between various grades of indices, the comprehensive environment-health index was calculated and contributed to classify the environment-health situation of 30 provinces, municipalities and autonomous regions in China which were divided into five grades by four predefmed limits. Comprehensive assessment indicates that the environment-health situation of the eastern and coastal areas is superior to that of inland which is the western regions with underdeveloped economy and rigorous natural condition.Especially, the Qinghai-Tibet and Yunnan-Guizhou plateaus in southwestern China are most vulnerable in the environment and population health. These fit in with the pattern of national socio-economic development, which fully shows that socio-economic context plays a dominant role in the improvement of environment-health in China. 相似文献