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11.
The Lanmuchang Tl deposit and its environmental geochemistry 总被引:8,自引:1,他引:7
Tl is a dispersed element and it seldom occurs in the form of independent minerals.The world annual production of Tl is about
13 ton, most of which is by-product separated from non-ferrous metal products. Lanmuchang is the only large-size independent
Tl deposit in the world. Bio-enrichment and hydrothermal reworking are the two important metallogenic mechanisms of this Tl
deposit. Samples of plant and animal organs and villagers’ urine as well as hair and nail (toenail) samples from the Tl mining
district were analyzed. Analytical results showed that the contents of Tl, Hg and As are high, suggesting that the residents
and villagers in the mining district have been affected by Tl-Hg pollution, and on the other hand, they can serve as the guidelines
for ore prospecting. The contents of Tl, Hg, and As in human beings and other organic bodies depend largely on the background
values of these metals in rock, ore, soil and water. 相似文献
12.
13.
A social scientist's perspective on the Census of Marine Life 总被引:1,自引:0,他引:1
Over 300 natural scientists in 53 nations are taking part in the Census of Marine Life (CoML) to investigate what lived, what lives, and what will live in the oceans. The CoML is a scientific experiment that is exploring the limits of ocean science. The paper discusses the potential applications of CoML research and the mechanisms by which the potential benefits can be measured and preserved. I recommend developing and integrating policy advisory committees with the natural science activities to both maximize the benefits of the research and to avoid unintended consequences. 相似文献
14.
A wide-ranging set of physical, urban, demographic, socioeconomic, and policy characteristics determines the spatial distribution of urban forests. Information on the characteristics surrounding tree removals on both public and private properties has received less attention in the literature. The purpose of this research was to analyze the spatiotemporal trends and geographic patterns of tree removals in Austin, Texas, between 2002 and 2011 in an effort to understand how site-specific characteristics influence urban tree removal and affect the overall distribution of Austin's urban forest. We examined permitted tree removals using a geographic information system (GIS) as well as spatial and statistical analyses. Specifically, we evaluated the degree to which variables related to various physical, urban, and socioeconomic conditions predicted tree removals. The results indicate that permitted tree removals and their associated characteristics in Austin have varied over the ten-year study period. Permitted tree removals increased over the study period and took place in the urban core and along the urban periphery. Permitted tree removals were more likely to be undertaken by college graduates and owner-occupants and to occur in more densely populated areas, closer to major streets, and on properties with older structures. The results of this research provide urban forest professionals with information on the location and intensity of permitted tree removals and the significant characteristics driving urban tree loss. 相似文献
15.
卡西欧fx-4800P计算器近年来普遍应用于工程测量工作中。针对卡西欧fx-4800P计算器具体特点,编制附合导线近似平差计算程序,并演示算例,可以提高计算准确率与工作效率。 相似文献
16.
The Lawn Hill circular structure in northwest Queensland contains unambiguous evidence of an extraterrestrial impact, including planar deformation features in quartz, impact diamonds, widespread shatter cone formation and impact melt breccia in the Mesoproterozoic basement. The question of its relevance to ore genesis is investigated because the world-class Century Zn – Pb deposit is situated at the conjunction of the 100+ km Termite Range Fault and the previously defined margin of the impact structure. The impact structure is considered to be a 19.5 km wide feature, this constrained in part by the outer margin of an annulus of brecciated and highly contorted limestone. New evidence is presented indicating impact into this Cambrian limestone, including: (i) ‘dykes’ of brecciated Cambrian limestone extending hundreds of metres into the Mesoproterozoic basement; (ii) highly contorted bedding in the limestone annulus compared with essentially undeformed limestone away from the impact site; as well as (iii) a 1 Mt megaclast of Mesoproterozoic Century-like ore suspended in the limestone. Through aerial photograph analysis, large-scale convoluted flow structures within the limestone are identified, and these are interpreted to indicate that parts of the Cambrian sequence may have been soft or only semi-consolidated at the time of impact. This highly contorted limestone bedding is suggested to represent slump-filling of an annular trough in response to impact-induced partial liquefaction of a sediment veneer. The age of impact is therefore considered to be concurrent with limestone formation during the Ordian to early Templetonian, at 520 – 510 Ma. Formation of the Century deposit is found to be unrelated to impact-generated hydrothermal activity, although some minor hydrothermal remobilisation of metals occurred. However, there was macro-scale remobilisation of gigantic ore fragments driven by impact-induced lateral and vertical injection of limestone into the Proterozoic sediments. The limestone-filled annular trough surrounds a 7.8 km diameter central uplift, consistent with formation of a complex crater morphology. 相似文献
17.
'In the shadow of hierarchy': meta-governance, policy reform and urban regeneration in the West Midlands 总被引:3,自引:0,他引:3
Mark Whitehead 《Area》2003,35(1):6-14
This paper explores the relationship between political hierarchy and the complex webs of political organization associated with urban governance. Deploying the concept of meta-governance and a study of urban policy reform in the West Midlands region of England, this paper claims that state and governmental hierarchies continue to have a crucial role in coordinating the activities of governance regimes in the UK. This paper concludes by considering the effects of hierarchical power on the systems of political participation and representation that are associated with urban governance. 相似文献
18.
Yubin JI Chenfeng JI Xiang ZOU Huixin LIU 《中国地球化学学报》2006,25(B08):186-186
To detect the excretion ratio of Toluene Diisocyanate (TDI) in mice feces by HPLC. The chromatogram column is C18-ODS, the mobile phase is Acetonitrile -H2O (45 : 55), the flow rate is 1mL/min. The detection wavelength is 254 nm, and the quantity is determined by outer mark method. The linear relationship of concentrations of TDI was shown well in the range of 1.2 mol/L-5.2 mol/L, and the recovery ratio was 96.48%, precision degree within the day was under 2.9% and in the day it was under 3.37%. This method was simple, convenient and viable. And the result showed that the excretive ratio of TDI in mice feces was distinctly increased with the dosage given by p.o, which proved that feces were the chief mode of archetypal excretion of TDI given by p.o. 相似文献
19.
南水北调西线一期工程调水区所涉及的6条河流(泥曲、达曲、色曲、杜柯河、玛柯河、阿柯河)坝址处均无实测的径流资料,开展该地区的水文研究属于无资料水文预报问题(PUBs)。利用年径流量的变差系数Cv值、年际变化绝对比率P和不均匀系数α对坝址下游的朱倭、朱巴、足木足、绰斯甲4站的实测年径流的年际变化进行分析,计算结果为各坝址径流年际变差系数Cv为0.15~0.26,表明调水区的多年径流量变化不大;年际变化绝对比率P为1.88~3.00,其中朱倭站的径流年际变化最大,最大径流量是最小径流量的3倍,绰斯甲站的最大径流量是最小径流量的1.88倍,4站的径流变化都不剧烈;径流不均匀系数α为0.58~0.75,表明该流域径流量的年际变化较为均匀;利用水文比拟法对坝址处的径流进行了计算,并根据R/S分析法对坝址处径流序列的未来趋势进行了初步分析,各坝址处的年径流序列的赫斯特系数均大于0.5,说明各径流序列的未来趋势具有持续性,即未来趋势与历史呈正相关,6个调水坝址中只有扎洛和克柯处的径流未来是减少的,其余坝址处径流都是增加的,这样西线一期工程调水区的河流有利于水资源的可持续开发利用。 相似文献
20.
公路工程项目管理模式设计—施工总承包的优势 总被引:1,自引:0,他引:1
通过不同管理模式的公路工程项目建设经验,分析传统公路工程项目管理模式得与失以及设计—施工总承包的优势,更好地保证设计与施工质量,有效控制造价,推进公路勘察设计与施工企业间战略重组,增强国际竞争力。 相似文献