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901.
Quantifying Relative Extinction Risks and Targeting Intervention for the Orchid Flora of a Natural Park in the European Prealps 总被引:1,自引:0,他引:1
SIMON PIERCE‡ ROBERTA M. CERIANI† MAURO VILLA† BRUNO CERABOLINI 《Conservation biology》2006,20(6):1804-1810
Abstract: Conservation currently relies largely on hindsight because demographic studies identify population decline after the event. Nevertheless, the degree of aggregation within a population is an "instantaneous" characteristic with the potential to identify populations presently at greatest risk of genetic impoverishment (via Allee effects and in-breeding depression) and local decline. We sought to determine the relative extinction risk for sympatric orchid species throughout Monte Barro natural park (Lecco, Italy), based on an index of dispersion ( I ) calculated from the size and location of subpopulations (recorded with GPS and mapped with GIS). Three population dispersion types were identified: (1) highly aggregated and locally abundant (large subpopulations restricted to particular sites; e.g., Gymnadenia conopsea [L.] R.Br.; I = 54.5); (2) widespread and moderately aggregated (opportunistic throughout the elevational range of the mountain; e.g., Listera ovata [L.] R.Br.; I = 18.9); and (3) weakly aggregated and locally rare (small, highly diffuse subpopulations; e.g., endemic Ophrys benacensis [Reisigl] O. & E. Danesch & Ehrend.; I = 4.4). Type 1 populations are more likely to respond to in situ intervention, whereas type 2 are relatively invasive species for which conservation intervention is not necessary, and type 3 are rare species that are least likely to respond to habitat management, for which ex situ conservation and population reinforcement would be most appropriate. Although our methodology provides only a "snapshot" of aboveground patterns of population dispersion, it can help target the application of in situ and ex situ conservation activities proactively and is of particular utility for parks for which a rapid assessment of local extinction risks is needed. 相似文献
902.
针对中国植物园稀有濒危植物的保护现状和存在问题进行分析,重点讨论了稀有濒危植物在植物园迁地保护的有效性问题,涉及稀有濒危植物在植物园迁地保护的生长和适应问题、稀有濒危植物在植物园重复栽培问题、稀有濒危植物在植物园迁地保护的有效种群大小问题、科学记录系统和监测中心的建立问题。就稀有濒危植物在植物园迁地保护的可持续发展提出了若干对策与建议:以植物园为基础形成保护的网络系统;加强稀有濒危植物迁地保护规划并突出重点;加强科学记录系统和监测中心的建立;多方筹措资金,加强支持强度;加强人才培训与学术交流。 相似文献
903.
Ijaz?M.?KhanEmail author Richard?R.?Simons Anthony?J.?Grass 《Environmental Fluid Mechanics》2005,5(5):393-413
Experiments have been carried out to investigate turbulence at and above roof-level in an urban environment, and to predict
the behaviour of street pollution from experiments using dye dispersion, for different roughness conditions and bed geometries.
The flow in the boundary layer above an idealised urban environment has been simulated in a laboratory water flume. Comparisons
have been made for the same model street canyon with and without the presence of upstream roughness. In the tests reported
here, model street canyons were aligned perpendicular to the flow direction, and velocity measurements made within and above
the model street canyons using a laser Doppler velocimeter (LDV). Flow visualisation techniques have also been used to confirm
the gross flow features from streak images. Turbulence generated from the upstream roughness has a significant effect on the
turbulence production and dispersion behaviour of the dye simulating pollution in street canyons. 相似文献
904.
The Great Lakes may be viewed as a coastal environment, affected by the same meteorological and physical forces as the coastal ocean. The U.S. EPA, Great Lakes National Program Office (GLNPO) has monitored the open waters of the lakes, annually, since 1983. As part of the U.S. EPA Environmental Monitoring and Assessment Program (EMAP), a pilot study was performed in Lake Michigan to compare the existing GLNPO deterministic sampling grid with the EMAP probabilistic grid. Results of chemical analyses of trophic status indicators (total phosphorus and chlorophyll a) as well as nutrients and conventional limnological measurements, from spring and summer surveys in 1992 indicate little difference between the grids in the offshore region of the lake. The few statistically significant differences may be due to station distribution throughout the lake, or simple chance. This might be expected due to the well mixed nature of the open waters of Lake Michigan. The detection of a long-term trend for total phosphorus in Lake Michigan benefits from an annual program: viewing cumulative frequency distributions based on a four year EMAP interval does not convey information on the decrease in phosphorus in the lake. If the EMAP sampling grid were to be used in the Great Lakes, pilots in each of the lakes would be necessary for utilization of the existing long-term record as a basis for trend detection. 相似文献
905.
906.
宁夏沙湖旅游区环境现状评价及发展趋势分析 总被引:4,自引:0,他引:4
对1993-1994年宁夏沙湖的环境现状进行了监测和综合评价。结果表明,湖水中度污染,已呈中度富营养化。按照国家GB1294-1中的A类标准,已不适合做天然浴场使用。沙丘仅为轻度污染,从发展趋势分析有加重的可能。 相似文献
908.
为评估杭州市典型室内公共场所空气中多溴联苯醚(PBDEs)的污染现状,2016年5~8月和9~12月期间,采用空气被动采样技术(PUF-PAS)在17家室内公共场所总计采集54个空气样品,经样品预处理和GC-ECD分析后,结果表明,5类环境空气样品中∑14PBDEs浓度均值大小依次为网咖(2470.43pg/m3)>建材市场(1119.87pg/m3)>电子市场(660.84pg/m3)>商场(478.37pg/m3)>图书城(182.18pg/m3).最主要的特征单体均为BDE-209,占总量的36.79%~56.21%,BDE-47、BDE-99、BDE-153、BDE-183也是PBDEs在空气中较主要的同系物,其最高浓度分别占7.77%,7.56%,6.32%和7.73%.评估PBDEs人群暴露水平的结果表明,网咖内暴露水平最高,图书城则为最低,其浓度分别为570.10和44.79pg/(kg×d).室内空气中,对人群PBDEs总摄入量贡献最高的特征单体是BDE-209,平均水平为18.44~323.70pg/(kg×d),最低的则为BDE-183,平均水平为1.75~20.05pg/(kg×d),目前杭州市各典型室内公共场所PBDEs人群暴露水平相比美国环境保护署(EPA)提出的参考剂量较低. 相似文献
909.
研究了不同分子结构的天然有机物质(NOM)模型化合物单宁酸(TA)、没食子酸(GA)和十二烷基苯磺酸钠(SDBS)对碳纳米管(CNTs)分散性的影响.通过计算得出,TA的临界胶束浓度(CMC)为1.12mmol/L,SDBS的CMC为0.24mmol/L,GA在所测试的浓度范围内没有形成胶束.比较NOM在CNTs表面的吸附过程和CNTs的分散过程,表明空间位阻和胶束包裹是2个促进CNTs分散的主要机理.借助透射电子显微镜(TEM)和测量悬浮的CNTs的平均流体动力学直径(DLS)结果表明,TA在较少的固相吸附量(Se ≈ 0.01mmol/g)就能使CNTs分散,归因于其吸附后刚性芳香三维结构的TA能形成的较大空间位阻;同样具有芳香平面结构的GA分子在CNTs表面的吸附需要达到一定的厚度(Se > 0.2mmol/g),才能有效地分散CNTs;具有烷基脂肪链的SDBS,需要在形成半胶束或胶束后(Se > 0.13mmol/g) CNTs才能有效地被分散.芳香族刚性结构和脂肪族柔性结构的模型化合物对CNTs的分散效果和机理存在较大的差别. 相似文献
910.
Sheikh Imran Uddin Ahmed 《环境质量管理》2019,29(2):51-55
This study reports the probability of increased mortality of people within the political border of Bangladesh due to the emission of fine particulate matter with diameters of 2.5 microns or less (PM2.5) from the Matarbari coal power plant (MCPP). A Gaussian plume dispersion model has been used for this estimation. The PM2.5 emission rate data are unavailable as the construction of MCPP is still in its initial stage; therefore, the anticipated PM2.5 emission rate has been estimated based on data from a number of coal‐fired power plants in India and China. To make this study more meaningful, two different emission rates have been considered representing the best‐case and worst‐case scenarios. In both cases, the intake fraction has been found to be 0.12×10?2, and the value of relative risk varies between 1.134 and 1.374, respectively. Finally, it is estimated that approximately 11.5 million people inside Bangladesh will be exposed to the PM2.5 emission from MCPP, and between 7,667 and 17,675 people will experience premature death every year. 相似文献