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651.
澜沧江水资源系统变化与大湄公河次区域合作的关联分析 总被引:3,自引:0,他引:3
针对澜沧江-湄公河水资源系统变化的跨境影响这一受到国际社会,特别是下游国关注的问题,结合流域各国水需求及区域性协定之规定,对比分析澜沧江大坝建设后对径流的影响,发现:(1)年出境水量呈小幅增长趋势,总体上有利于下游水资源利用;(2)个别年份枯季出境水量明显减少的主要原因是降水少和个别电站运行失误所致,电站本质上不会对下游用水和生态产生实质性危害;(3)出境水量变化主要对下游中上段产生明显影响,越往下游影响力越小;(4)出境水质稳定。建议:尽早制定流域综合规划和国际水分配方案;合理调整水库运行方案,避免出境水量或水位的大幅变化,减少跨境负面影响,维护区域合作。 相似文献
652.
Journal of Geographical Sciences - Flood is one of the severest natural disasters in the world and has caused enormous causalities and property losses. Previous studies usually focus on flood... 相似文献
653.
This work is part of a research study which is intended to study the degree of anthropogenic influences of the trace metal
distribution of soils from Danang-Hoian area (Vietnam). Cu, Ni, Zn and Zr show significant effects in most of the cultivated
soil categories, especially in the industrial soils. Extremely high levels of Pb (up to 742 μg/g) are observed in the industrial
soil category, which shows an enrichment factor 114 as compared to rural soils. Cd shows only a relative local enrichment
with the maximum level of 4.6 μg/g in urban soils. Sequential extraction was performed in selected samples to evaluate the
geochemical trace metals. The result indicates that Zn and Cr are mainly found in the crystal and amorphous Fe oxide bounded
forms. The contents of Cr in these fractions comprise more than 94% of total extractable Cr. In the case of Zn, 85% of total
extractable Zn is in fractions FV and FVI. Cu is mainly found in the organic fraction at an average of 39.3% of total extractable content. On the other hand, heavy
metal contents show an increasing tendency in the fine fraction (silt and clay).
Received: 4 February 1998 · Accepted: 26 November 1998 相似文献
654.
The prime objective of primary health care provision is the maintenance or improvement of the population's health. The equitable distribution of resources is paramount to this and measures of disadvantage are implemented to assess differential levels of need as a basis for calculating deprivation payments according to general practitioner workload. Despite research that highlights the benefits of measures of social disadvantage, indices have not been used to fundamentally shape resource allocation for health authorities. This paper uses the results from a patient survey into utilization behaviour to define and model the determinants of the need for health care based on components of relative need and accessibility. Proxy indicators are derived from routine sources of data to create an Index of Relative Disadvantage (IRD). A sensitivity analysis confirms the robustness of the index and shows that—although the index employs a wider range of variables than most previous deprivation indices—there is no gross data redundancy. Simplified versions of the index are also explored and evaluated. The IRD developed here is closely correlated with other indices of disadvantage, but its greater breadth and more logical construction mean that it may be more likely to be a more widely applicable instrument for health care planning of resource allocation. 相似文献
655.
656.
旅游对目的地社会文化影响的研究进展 总被引:4,自引:0,他引:4
旅游发展使旅游目的地社会生活的各个方面都发生了变化, 这个问题从20 世纪60 年代 开始就引起了国外学者的关注, 并作为热点问题持续至今。本文结合人类学家的部分研究成果, 从国内外相关研究的成果数量、研究内容和研究方法入手, 系统总结了当前国内外关于旅游对目 的地社会文化影响研究在理论、观点、方法、实践、模型等方面取得的最新进展, 指出了当前该领 域研究中的薄弱环节和我国学者在研究中出现的主要问题: 实证研究较多, 理论总结少; 定性方 法多, 定量测算少; 研究观点的片面性; 研究指标各异, 可比性不强。从长远的角度看, 研究成果和 实际发展管理的紧密结合、研究技术的突破和理论体系的确立、多学科融合综合研究将成为这个 领域的主要发展方向。 相似文献
657.
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
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
658.
The Soufrière Hills Volcano, Montserrat, erupting since 18 July 1995, intensified its degassing in early 1996 with the continuing
growth of the lava dome inside the summit crater. During this period of increased activity, between 11 and 18 March 1996,
we measured gases and particles within the visible plume to determine whether at that time it posed a health risk to the population
of Plymouth, the capital town, which is 5 km southwest (downwind) and was then still occupied. Gravimetric measurements were
made of total suspended particles (TSP) and particles having an aerodynamic diameter of less than 10 μm (PM10). Measurements were made of sulphur dioxide (SO2), hydrochloric acid (HCl), hydrofluoric acid (HF), nitric acid (HNO3), acetic acid (CH3COOH), formic acid (HCOOH), and particulate sulphate (SO4
2–), chloride (Cl–), nitrate (NO3
–), fluoride (F–), methanesulphonate (CH3SO3
–), acetate (CH3COO–), formate (HCOO–), ammonium (NH4
+), sodium (Na+) and acidity (H+). Trace metals having human health implications [chromium (Cr), nickel (Ni), cobalt (Co), copper (Cu), zinc (Zn), arsenic
(As), selenium (Se), cadmium (Cd), tin (Sn), mercury (Hg) and lead (Pb)] were also determined. Mean concentrations of HCl,
SO2 and HF obtained in the town of Plymouth were 14.0, 5.9 and 0.8 ppbv, respectively. Corresponding concentrations in the mixed
plume on the crater edge were 533, 168 and 22 ppbv. There were no direct emissions of HNO3, although nitrate was detected in coarse particles at the source. Higher concentrations of CH3COOH and HCOOH were measured close to the crater. Mean TSP and PM10 were 64 and 15 μg m–3 in Plymouth, and 455 and 47 μg m–3 on the upper volcano slope. Aerosols were highly acidic at the source but rapidly neutralised during transport. Trace metals
were enriched in the aerosol relative to crater surface material. The concentrations of the acid gases, sulphur dioxide in
particular, and particles were found to be too small to pose a health hazard at the time of these measurements, when relatively
modest volcanic activity was occurring.
Received: 9 September 1998 / Accepted: 29 August 1999 相似文献
659.
胶州湾扇贝养殖对海域环境影响的初步研究 总被引:5,自引:0,他引:5
在2004年11月17日对胶州湾西部扇贝养殖区及周围海区进行的综合海洋环境调查的基础上,分析了胶州湾秋季扇贝养殖区与非养殖区的海洋环境状况,初步探讨了扇贝养殖在收获期对养殖区环境的影响。胶州湾养殖区表层水中COD和无机营养盐含量,除了NO2 -N的变化不明显外,均高于非养殖区的值。养殖区底层水中溶解氧含量和表层沉积物中硫化物的含量均明显超标。因此,肢州湾的扇贝养殖在收获期对环境的影响也是综合性的,且养殖海域的环境同时受陆源、水动力状况及养殖活动的综合影响。 相似文献
660.
R. Corobov 《GeoJournal》2002,57(3):195-202
Statistical methods for assessing crop sensitivity and vulnerability to climate change in Moldova were demonstrated and the
following procedures were discussed: (1) projections of likely agroclimatic change; (2) assessments of crop sensitivity to
climate change; and (3) assessments of the impact of climate change on crops. In order to predict the future agroclimate,
key meteorological variables were transformed statistically to correspond to changes in plants' heat and water supply characteristics.
Sensitivity of crop production was examined for corn and winter wheat. By combining the agroclimatic changes with crop response,
possible impacts have been estimated and form a basis for possible adaptation strategies. It was shown that regional climate
change can result in elevated aridity of Moldova's territory, especially during periods of crop growth. Cultivation of cereal
crops in new agroclimatic conditions without adaptation measures will negatively affect yields, especially of winter wheat,
whose yield decrease may be 18–39% by 2020s and 22–50% by 2050s. Corn yields may increase by 0–3% and 1–6%, respectively.
As an example of adaptation, it is shown that the use of an increased number of late hybrids results in a 25–35% increase
in corn yields.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献