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121.
实验采用DMA-80自动测汞仪直接测定土壤中的汞含量,详细介绍了土壤样品中汞分析条件的选择,方法在0.4—400ng范围内,线性良好,其检出限为0.2ug/kg。 相似文献
122.
123.
Johan Svensson Jon Andersson Per Sandström Grzegorz Mikusiński Bengt Gunnar Jonsson 《Conservation biology》2019,33(1):152-163
Loss of natural forests by forest clearcutting has been identified as a critical conservation challenge worldwide. This study addressed forest fragmentation and loss in the context of the establishment of a functional green infrastructure as a spatiotemporally connected landscape-scale network of habitats enhancing biodiversity, favorable conservation status, and ecosystem services. Through retrospective analysis of satellite images, we assessed a 50- to 60-year spatiotemporal clearcutting impact trajectory on natural and near-natural boreal forests across a sizable and representative region from the Gulf of Bothnia to the Scandinavian Mountain Range in northern Fennoscandia. This period broadly covers the whole forest clearcutting period; thus, our approach and results can be applied to comprehensive impact assessment of industrial forest management. The entire study region covers close to 46,000 km2 of forest-dominated landscape in a late phase of transition from a natural or near-natural to a land-use modified state. We found a substantial loss of intact forest, in particular of large, contiguous areas, a spatial polarization of remaining forest on regional scale where the inland has been more severely affected than the mountain and coastal zones, and a pronounced impact on interior forest core areas. Salient results were a decrease in area of the largest intact forest patch from 225,853 to 68,714 ha in the mountain zone and from 257,715 to 38,668 ha in the foothills zone, a decrease from 75% to 38% intact forest in the inland zones, a decrease in largest patch core area (assessed by considering 100-m patch edge disturbance) from 6114 to 351 ha in the coastal zone, and a geographic imbalance in protected forest with an evident predominance in the mountain zone. These results demonstrate profound disturbance of configuration of the natural forest landscape and disrupted connectivity, which challenges the establishment of functional green infrastructure. Our approach supports the identification of forests for expanded protection and conservation-oriented forest landscape restoration. 相似文献
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125.
Dragan R. Milićević Verica B. Jurić Srđan M. Stefanović Slavica M. Vesković-Moračanin Saša D. Janković 《Journal of environmental science and health. Part. B》2013,48(8):781-787
This study was undertaken to compare two different analytical methods for the determination and confirmation of ochratoxin A (OTA) in blood serum, kidney and liver of pigs. Sample clean-up was based on liquid-liquid phase extraction. The detection of OTA was accomplished with high-performance liquid chromatography (HPLC) combined either with fluorescence detection (FL) or electro spray ionization (ESI+) tandem mass spectrometry (MS–MS). Comparative method evaluation was based on the investigation of 90 samples of blood serum, kidney and liver per animal originating from different regions of Serbia. The analytical results are discussed in view of the respective method validation data and the corresponding experimental protocols. In general, analytical data obtained with (LC–MS–MS) liquid chromatography electro spray tandem mass spectro metry detection offered comparable good results at the sub-ppb concentration level. The results indicate that the liquid chromatography electro spray tandem mass spectrometric (LC-MS/MS) method was more specific and sensitive for the analysis and confirmation of ochratoxin A in pig tissues then high pressure liquid chromatography (HPLC) method after methylation of OTA. 相似文献
126.
森林旅游开发中环境保护问题的博弈分析 总被引:5,自引:0,他引:5
江民锦 《湖南环境生物职业技术学院学报》2006,12(2):184-187
介绍了博弈论的基本内容,运用了博弈论的基本原理分析和认识森林旅游开发和周边地区生态环境保护之间存在的矛盾,阐述了博弈论的基本理论在森林旅游开发环保中的应用,分析指出应结合市场机制和政府政策改变博弈方的收益,使博弈达到有利于环境保护的纳什均衡,提高森林旅游开发中的环境保护效率,以及处理森林旅游开发中环境保护问题的有效决策. 相似文献
127.
北京城市生态系统的能值动态分析 总被引:3,自引:0,他引:3
采用能值理论与分析方法,对北京市1990~2001年间的能值结构动态进行了分析,并采用人均能值、能值密度、生态功能潜力、人口基本承载力、能值自给率、能值货币比率、环境负载率、输入能值比等重要能值指标对该时期北京市城市生态系统的能值状况作了详细分析。研究表明,北京城市生态系统正处于较高发展水平,已基本跨入发达国家水平的行列;但高强度、快速发展给本市带来了巨大的生态环境压力,未来北京的可持续能力建设已势在必行。文章也提出了北京城市生态系统可持续发展能力建设的基本方向。 相似文献
128.
In the annual bumblebee Bombus terrestris, the onset of queen-worker conflict over male production is seasonally and socially constrained. Workers will do better if they start to reproduce (the so-called competition phase) only after ascertaining that larvae are committed to gyne development but before the season ends because they gain more by rearing sister-gynes than their own sons. Here, we tested two nonmutually exclusive hypotheses as to what triggers the onset of worker reproduction: Workers can directly monitor larval development and/or workers eavesdrop on the queen signal that directs gyne development. Exposing workers to gyne larvae through a double mesh did not advance the competition phase compared to control colonies. However, when workers, but not the queen, were allowed contact with gyne larvae, both the competition phase and gyne production were advanced. Thus, while larvae do not emit a volatile pheromone that discloses their developmental route, the physical contact of workers with such larvae triggers early competition phase. However, workers exclusively exposed to worker larvae (colonies prevented from producing gyne larvae) started to reproduce at the same time as control colonies. Replacing the resident queen with an older queen (from gyne-rearing colonies) advanced the competition phase, irrespective of worker age. The results are consistent with the hypothesis that workers eavesdrop on the queen pheromones. This is adaptive because it allows workers a broader time-window for reproduction and thus to gain fitness from rearing both sister-gynes and sons before the season ends without affecting colony development. 相似文献
129.
In ant societies, workers do not usually reproduce but gain indirect fitness benefits from raising related offspring produced
by the queen. One of the preconditions of this worker self-restraint is sufficient fertility of the queen. The queen is, therefore,
expected to signal her fertility. In Camponotus floridanus, workers can recognize the presence of a highly fertile queen via her eggs, which are marked with the queen's specific hydrocarbon
profile. If information on fertility is encoded in the hydrocarbon profile of eggs, we expect workers to be able to differentiate
between eggs from highly and weakly fertile queens. We found that workers discriminate between these eggs solely on the basis
of their hydrocarbon profiles which differ both qualitatively and quantitatively. This pattern is further supported by the
similarity of the egg profiles of workers and weakly fertile queens and the similar treatment of both kinds of eggs. Profiles
of queen eggs correspond to the cuticular hydrocarbon profiles of the respective queens. Changes in the cuticular profiles
are associated with the size of the colony the queen originates from and her current egg-laying rate. However, partial correlation
analysis indicates that only colony size predicts the cuticular profile. Colony size is a buffered indicator of queen fertility
as it is a consequence of queen productivity within a certain period of time, whereas daily egg-laying rate varies due to
cyclical oviposition. We conclude that surface hydrocarbons of eggs and the cuticular profiles of queens both signal queen
fertility, suggesting a major role of fertility signals in the regulation of reproduction in social insects. 相似文献
130.