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41.
42.
生态足迹影响因子的定量分析   总被引:2,自引:0,他引:2  
人口的膨胀和人类工业化进程的加剧,使得人类向自然界获取越来越多的资源,同时向环境源源不断的输入废弃物,已经严重超过了自然生态系统的供给能力和环境容量,生态环境日益恶化,水土流失、草场退化、植被消亡、生物多样性锐减、全球变暖等情况已经严重到难以遏制的地步,危及到人类自身的生存。在和平与发展成为世界两大主题的今天,人们越来越关注可持续发展的问题。在现有资料的基础上,利用主成分分析方法,定量地讨论了中国各省(区市)1999年生态足迹大小与其影响因子间的关系。结果表明,生态足迹的大小是各省(区市)的大中型企业个数、全社会固定生产投资等众多因子共同作用的结果,其中总人口和GDP是生态足迹大小的主要影响因子,其因子载荷量分别达到了0.940和0.913。值得一提的是非农业人口与生态足迹的相关系数超过了农业人口,这说明由于消费模式和生活水平等的差异,非农业人口对生态足迹的影响大于农业人口对生态足迹的影响。在此基础上建立了生态足迹影响因子的多元线性回归模型,以期为生态足迹在进行区域可持续发展评价的方法上提供新的思路。  相似文献   
43.
The effect of industrial air pollution on natural small mammal populations has been studied in the northern taiga subzone of the boreal forest zone. The results of long-term monitoring have been used to demonstrate the possibility of predicting changes in the main population and community characteristics of the animal species studied as dependent on the degree of anthropogenic impact.  相似文献   
44.
We report on the prenatal diagnosis of ring chromosome 15 in a fetus with increased nuchal fold and intrauterine growth restriction (IUGR). A 27-year-old woman gravida 2, para 1 had normal maternal serum screen tests in the early second trimester of the index pregnancy. Fetal nuchal fold thickening up to 8 mm was incidentally found during the routine obstetric ultrasound scan at 20 weeks' gestation. Amniocentesis was undertaken and the fetal karyotype was found to be 46,XY,r(15) on cytogenetic study. Fluorescence in situ hybridization (FISH) using a telomeric probe of chromosome 15 demonstrated a terminal deletion on the q arm of the ring-shaped chromosome 15. This is the first report of a prenatally diagnosed case of ring chromosome 15. Moreover, nuchal fold thickness in the second trimester may have a role in its prenatal diagnosis. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   
45.
This work, carried out within the framework of the PRISMA II project, aims at evaluating the effects of the Po River flow on primary productivity, measured by C with in situ sample incubations. A total of four cruises was carried out in late winter and early summer (1996-1998) along transects from the coast offshore. In both seasons, the highest primary productivity was found in the most oligohaline stations. The effects of the Po River inputs were therefore clearly evident in the westernmost area, both in high productivity values and in the shape of productivity profiles. In late winter, extensive blooms of Skeletonema costatum and Pseudo-nitzschia delicatissima resulted in productivity values that were sometimes higher than in early summer. In early summer 1996, greatly reduced river flow clearly influenced productivity which was much lower than in 1997.  相似文献   
46.
In the last 10 years, several studies have been carried out on the fish fauna of the Ustica Island marine reserve, yet no investigation was specifically addressed to the cryptobenthic fish assemblage. The first task of this study, conducted along the shallow rocky reefs of Ustica, was to determine the species composition, diversity and relative density of the resident cryptobenthic fishes. Furthermore, we aimed to assess the effects of some macro- and microscale habitat characteristics on the distribution pattern of fishes. In particular, the effect of predator density was indirectly evaluated by comparing density data collected within and outside the integral reserve zone. Overall, 20 species belonging to Blenniidae, Gobiidae, Tripterygiidae, Scorpaenidae and Gobiesocidae were recorded. Gobius bucchichi, Scorpaena maderensis, Tripterygion delaisi, T. melanurus and T. tripteronotus were the numerically dominant and most common species. The effects of zone (i.e. of predator density), bottom type and depth on species richness, diversity and evenness were not significant. A greater total fish density was observed on stones compared with rocky cliff and plateau, but only in the shallowest depth range. At level of single species, G. bucchichi was more abundant inside than outside the integral reserve, but only on stones and at 0–2 m depth range. Density of G. bucchichi was generally higher on stones than on rocky cliffs or plateau and between 0 and 5 m depth, although these differences were not always significant. T. delaisi was conversely more abundant in the deepest stratum (7–10 m). Canonical analyses demonstrated that bottom type and depth influenced significantly the fish assemblage structure. The observed differences in the assemblage structure relied mainly upon the dominant species. T. tripteronotus was mainly associated with rocky plateau and the intermediate depth range (3–5 m), whereas S. maderensis, T. melanurus and Lipophrys trigloides inhabited preferentially the rocky cliffs. At microscale level, the habitat choice of the investigated species was almost entirely based on whether the substrate was either vegetated or composed of bare rock. T. delaisi and T. tripteronotus were associated with substrata covered by algae, whilst G. bucchichi, S. maderensis and T. melanurus preferred bare rock bottoms. In some species, the electivity indices for the less abundant type of cover, measured at different spatial scale, changed accordingly. For instance, the smaller the size of the sampled area, the higher was the intensity of the association between G. bucchichi and Anemonia viridis.  相似文献   
47.
48.
采样点位置的确定是烟尘测试中的一项基础工作。在全国沿用10多年的确定圆形圆形烟道烟尘采样点位置的计算表中的数据,经验算有60%有误;原来以烟道中心为基准的计算公式虽然正确,但实用性差。为了进一步完善烟气测试理论,提高监测质量,提出以烟道内壁为基准的新计算公式。运用新、旧2种计算公式得到一致的计算结果—新计算表,进一步证实了原计算表中的错误。  相似文献   
49.
50.
The past two decades have witnessed an increase in the exploration for, and development of, mineral resources at Arctic latitudes. Such effort has resulted in the commencement of production at a number of different localities in close proximity to the ocean. Since proximity to a source of transportation for the conveyance of concentrates to the market is a primary requirement governing the economic decisions for the mine to proceed, it is logical that ore deposits near a coastline are primary targets for development.

Closely tied to coastal mining developments is the need to dispose of tailings and waste rock in the most economical manner. Prior to the advent of heightened public awareness and environmental concern, and the enactment of pollution legislation, disposal practices were largely based upon convenience. Currently, however, proposed disposal and operating practices receive closer scrutiny, with a view to providing adequate protection for aquatic resources and habitat. This paper summarizes some of the features of three Arctic mines, wastes from which enter the marine environment, and compares the disposal practices used at each to measures of environmental change as indicated by metal concentrations in various media.  相似文献   
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