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排序方式: 共有832条查询结果,搜索用时 31 毫秒
731.
732.
不同垃圾填埋单元土壤--植物系统中汞的污染和迁移 总被引:4,自引:0,他引:4
对上海老港垃圾填埋场不同年份填埋单元的表层履土,以及典型植物中汞的分布进行了分析研究。结果发现,自1989-2001年共13a间不同时间的垃圾填埋单元表层土壤中,汞浓度与填埋时间有一定关系:从1989年到1993年,土壤汞浓度呈逐年递减趋势;从1998年到2001年又呈递增趋势;而中间几年出现汞浓度异常现象。土壤总汞、结合态汞和可挥发汞的浓度与土壤有机质含量有显著的相关性,相关系数分别为0.8147、0.8045和0.8213。另外,被调查植物体内汞的分布特点为:叶汞>根汞>茎汞。填埋时间较长的几个单元中,典型植物(加拿大黄花)的根汞与土壤可挥发汞有较好的相关性。 相似文献
733.
734.
Cost-Efficiency of Decaying Wood as a Surrogate for Overall Species Richness in Boreal Forests 总被引:5,自引:0,他引:5
Abstract: Decaying wood is one of the most important elements for species richness in boreal forests. We tested how well reserve selection based on the amount and quality of decaying wood results in a representation of four ecologically different taxa (beetles, birds, wood-inhabiting fungi, and vascular plants). We also compared the cost-efficiency of the use of dead-wood indicators with comprehensive species inventory. Our database included 32 seminatural old-forest stands located in northern Finland. Decaying wood was a relatively good indicator of saproxylic species but not overall species richness. Even though dead wood did not reflect accurately overall species richness, our results indicated that the use of decaying wood as an indicator in site selection was more cost-efficient than using information from large-scale species inventories. Thus, decaying wood is a valuable surrogate for species richness, but other cost-efficient indicators that reflect the requirements of those species which are not dependent on decaying wood should be identified. 相似文献
735.
在综合各 株洲霞 湾污水处 理厂选址 影响因 素的基础 上,用 灰色 系统 关联 模式 对污 水处 理厂选址进 行讨论 分析,排除 人为的 主观任意 性,取得 令人满意 的结果 相似文献
736.
利用高时间分辨率自动测汞仪(Tekran 2537B)于2017年6月~2018年5月对武夷山气态元素汞(GEM)进行了连续1a的观测.结果表明,武夷山GEM年均浓度为(1.70±0.43)ng/m3,稍高于北半球背景值,表明武夷山受到一定程度的大气汞污染.GEM浓度表现为冬季>秋季>春季>夏季,季风和风速是影响武夷山GEM季节变化的主要因素.武夷山四季GEM表现为不同的日变化特征,早上8:00之后,春秋季GEM继续呈现下降趋势,其他季节则呈现先升后降再上升,并在晚上不同时刻出现峰值.GEM值白天低于晚上,这与风速和汞的长距离迁移有关.后向轨迹和浓度权重轨迹分析结果表明,偏西风背景下污染气团经江西向武夷山输送是大气汞迁移的主要路径,而江西和福建中北部为武夷山大气汞污染的潜在源区.△GEM/△CO值表明武夷山GEM汞污染主要来源于人为工业排放,生物质燃烧贡献较弱. 相似文献
737.
Catherine Meur-Férec 《Journal of Coastal Conservation》1997,3(2):121-132
In Europe, Britain was relatively early in being aware of the necessity of conserving natural coastal sites, though not as
early as The Netherlands. In the 1960s and 1970s, increasing economic and tourist pressures in Europe prompted measures geared
to the protection of other coasts in Europe. The promptness of the British reaction was a result of a sensitive public opinion
and of powerful private trusts (National Trust with Enterprise Neptune) rather than of a commitment by the Government. In
France a specific organization, in part inspired by the British principle, was set up. However, the French system is based
much more on a public authority, theConservatoire de l’Espace Littoral et des Rivages Lacustres and on legislation (Coastal Law of 1986). Although very different in the beginning, French and British conservation politics
today show many similarities, along with the similarities in the concerns of both countries. 相似文献
738.
Cleanup standards at hazardous waste sites include (i) numeric standards (often risk-based), (ii) background standards in which the remediated site is compared with data from a supposedly clean region, and (iii) interim standards in which the remediated site is compared with preremediation data from the same site. The latter are especially appropriate for verifying progress when an innovative, but unproven, technology is used for remediation. Standards of type (i) require one-sample statistical tests, while those of type (ii) and type (iii) call for two-sample tests. This paper considers two-sample tests with an emphasis upon the type (iii) scenario. Both parametric (likelihood ratio) and nonparametric (linear rank) protocols are examined. The methods are illustrated with preremediation data from a site on the National Priorities List. The results indicate that nonparametric procedures can be quite competitive (in terms of power) with distributional modelling provided a near optimal rank test is selected. Suggestions are given for identifying such rank tests. The results also confirm the importance of sound baseline sampling; no amount of post-remediation sampling can overcome baseline deficiencies.This paper has been prepared with partial support from the United States Environmental Protection Agency under a Cooperative Agreement Number CR-815273. The contents have not been subject to Agency review and therefore do not necessarily reflect the views or policies of the Agency and no official endorsement should be inferred. 相似文献
739.
P. P. Pomeroy P. R. Redman S. J. S. Ruddell C. D. Duck S. D. Twiss 《Behavioral ecology and sociobiology》2005,57(6):546-556
Consistent, widespread fine-scale preferences for breeding sites may favour the emergence of intrasexual associations and hence sociality. Pairwise association was defined for a terrestrially breeding phocid seal in which intraseasonal colony mixing is limited and mothers spend only 3 weeks ashore breeding. Interannual associations may occur between pairs of breeding female grey seals at North Rona, Scotland because of pupping site fidelity, 90% return rates and limited variability in parturition dates that individual mothers show. Associations can occur when mothers are found together irrespective of location, or because of joint preferences for locations. Mothers were sedentary and were unlikely to interact if they are separated by >20 m. Using spatial and temporal association criteria, 160 of 176 of known mothers had intraseasonal associations with at least one other mother, with 14 of 126 (11.1%) of associations repeated in 2 years. The likelihood of female association in 2 years as a result of site fidelity, parturition date variation and pupping site quality was modelled. Interannual association between mothers that changed their pupping sites by up to the median observed pupping site fidelity (<40 m) was indistinguishable from our models predictions. However, the number of mothers that showed interannual association after displacements of >40 m from their previous years pupping sites was almost five times greater than the model predicted. We conclude that active association between adult female grey seals is not determined solely by habitat preference, and argue that examination of simple sociality in temporarily aggregating species can contribute significantly to socioecological models of social evolution.Communicated by F. Trillmich 相似文献
740.
N. Tommerup F. Søndergaard A. Hanauer I. Oberle J. Bang B. Barbi B. Bech K. Davies U. Froster-Iskenius K.-H. Gustavson C. B. van der Hagen A. Heiberg U. Kristoffersen M. Mikkelsen P. Miny K. B. Nielsen K. Rasmussen A. Schinzel L. Tranebjaerg T. Tønnesen J. Wahlström 《黑龙江环境通报》1991,11(8):609-619
Early prenatal diagnosis of the fragile X was attempted in 44 pregnancies, including one twin pregnancy at risk of Martin-Bell (MB) syndrome. The sex ratio was 24M:21F. The fragile site was reproducibly demonstrated in cultured chorionic villus (CV) cells in eight male and five female fetuses. Six of the male and three of the female fetuses were terminated. Simultaneous RFLP analysis provided confirmative data with flanking DNA markers in 3 of 13 analysed cases. Recombination and/or non-informativeness at available distal and/or proximal loci were found in nine cases. In one male fetus, discordance between the haplotype and cyto-genetics (fragile-X-negative) suggested the presence of a normal male transmitter, a double meiotic cross-over within the region, or a false-negative cytogenetic diagnosis. However, discordance between prenatal and post-termination/postnatal cytogenetic findings was not observed in this series. The use of excess thymidine for induction of the fragile X in cultured CV cells provided in the majority of cases a safe and rapid method for cytogenetic diagnosis, with options for early induced termination in fragile-X-positive pregnancies, for simultaneous RFLP analysis, and for subsequent second-trimester analysis of fetal blood in complicated cases. 相似文献