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91.
The structure of most forest communities in the European forest–steppe, including protected areas, has been disturbed. The adverse consequences of these disturbances include the incomplete age structure of the populations of cenosis-forming species and the irreversibility of successions. The conservation of biodiversity in the structurally disturbed communities is impossible without human intervention, which must be aimed at restoring their age heterogeneity with regard to their specific ecological features. 相似文献
92.
为控制污水管道产生的有害气体对管道设施和周围环境造成的不利影响,通过搭建带有搅拌的反应器系统,来模拟实际污水管道,探究脉冲通气对污水管道内有害气体的控制效果及生物群落变化的影响。研究表明:脉冲通气能有效控制有害气体的产生,在水流速度为0.2 m·s−1时,硫化氢(H2S)、甲烷(CH4)、一氧化碳(CO)的抑效果最好,其抑制率分别为98.7%,44.4%,92.5%;在脉冲通气作用下,古菌群落的生物多样性不断减少,细菌群落的生物多样性不断增加;同时,脉冲通气也改变了生物群落结构,其群落结构变化与气相参数的变化是相一致的。 相似文献
93.
基于短程硝化处理后的老龄垃圾渗滤液,含有大量难降解有机污染物,且氨氮和化学需氧量浓度高,C/N比低等特点。本研究以厌氧硝化污泥作为接种污泥,采用升流式厌氧污泥床反应器(UASB),快速启动厌氧氨氧化反应,对其进行深度脱氮。探究启动厌氧氨氧化反应的最佳条件和脱氮性能,根据污泥形貌特征和微生物群落结构的变化,阐明厌氧氨氧化的作用机理。结果表明,厌氧氨氧化快速启动最佳条件:温度为(30±1) ℃、初始pH为7.5、NO2−/NH4+为1.25~1.50、无外加碳源和MLSS为4 200 mg·L−1。历经60 d后,厌氧氨氧化成功启动,进水TN容积负荷最高为0.45 kg·(m3·d)−1,TN容积负荷去除速率最高为0.36 kg·(m3·d)-1,NH4+-N、NO2−-N和TN去除率超过80%。同时,UASB运行至第60天时,接种污泥形貌呈现花椰菜结构,微生物群落多样性减少,Planctomycetes门为优势菌群,其丰度为44.4%。Candidatus Brocdia属为第一优势菌属,其丰度为42.8%,证实厌氧氨氧化快速启动成功,AnAOB利用NO2−-N为电子受体,以NH4+-N为电子供体实现深度脱氮。综上所述,厌氧氨氧化的快速启动可为短程硝化处理后的老龄垃圾渗滤液深度脱氮提供参考。 相似文献
94.
Henry P. Huntington Andrey Zagorsky Bjrn P. Kaltenborn Hyoung Chul Shin Jackie Dawson Maija Lukin Parnuna Egede Dahl Peiqing Guo David N. Thomas 《Ambio》2022,51(2):298
The Arctic Ocean is undergoing rapid change: sea ice is being lost, waters are warming, coastlines are eroding, species are moving into new areas, and more. This paper explores the many ways that a changing Arctic Ocean affects societies in the Arctic and around the world. In the Arctic, Indigenous Peoples are again seeing their food security threatened and cultural continuity in danger of disruption. Resource development is increasing as is interest in tourism and possibilities for trans-Arctic maritime trade, creating new opportunities and also new stresses. Beyond the Arctic, changes in sea ice affect mid-latitude weather, and Arctic economic opportunities may re-shape commodities and transportation markets. Rising interest in the Arctic is also raising geopolitical tensions about the region. What happens next depends in large part on the choices made within and beyond the Arctic concerning global climate change and industrial policies and Arctic ecosystems and cultures. 相似文献
95.
Effects of a tropical cyclone on the drinking-water quality of a remote Pacific island 总被引:2,自引:0,他引:2
The effect of a cyclone (Ami, January 2003) on drinking-water quality on the island of Vanua Levu, Fiji was investigated. Following the cyclone nearly three-quarters of the samples analysed did not conform to World Health Organisation (WHO) guideline values for safe drinking-water in terms of chlorine residual, total and faecal coliforms, and turbidity. Turbidity and total coliform levels significantly increased (up 56 and 62 per cent, respectively) from pre-cyclone levels, which was likely due to the large amounts of silt and debris entering water-supply sources during the cyclone. The utility found it difficult to maintain a reliable supply of treated water in the aftermath of the disaster. Communities were unaware they were drinking water that had not been adequately treated. Circumstances permitted this cyclone to be used as a case study to assess whether a simple paper-strip water-quality test (the hydrogen sulphide, H(2)S) kit could be distributed and used for community-based monitoring following such a disaster event to better protect public health. The H(2)S test results correlated well with faecal and total coliform results as found in previous studies. A small percentage of samples (about 10 per cent) tested positive for faecal and total coliforms but did not test positive in the H(2)S test. It was concluded that the H(2)S test would be well suited to wider use, especially in the absence of water-quality monitoring capabilities for outer island groups as it is inexpensive and easy to use, thus enabling communities and community health workers with minimal training to test their own water supplies without outside assistance. The importance of public education before and after natural disasters is also discussed. 相似文献
96.
通过对2009年11月12日在四川省广元市三堆镇马口村举行的自然灾害应急演练进行初步的分析研究,总结出了从前期准备、正式实施到演练评估的农村社区自然灾害应急演练基本流程和方法。在马口村自然灾害应急演练的前期准备阶段,根据当地实际情况选择了滑坡、泥石流为演练的自然灾害背景,制定了3级响应演练模式,并细化了各级响应的启动标准。在演练的正式实施阶段,采用了参与式的演练方案设计方法,充分调动了当地群众的积极性。演练结束后在现场发放调查问卷,对演练进行了多方面、多角度的评估,演练基本达到了预定目标。 相似文献
97.
ROBERT C. BARBOUR‡ LYNNE G. FORSTER SUSAN C. BAKER† DOROTHY A. STEANE BRADLEY M. POTTS 《Conservation biology》2009,23(5):1146-1155
Abstract: The developing field of community genetics has the potential to broaden the contribution of genetics to conservation biology by demonstrating that genetic variation within foundation plant species can act to structure associated communities of microorganisms, invertebrates, and vertebrates. We assessed the biodiversity consequences of natural patterns of intraspecific genetic variation within the widely distributed Australian forest tree, Eucalyptus globulus. We assessed genetic variation among geographic races of E. globulus (i.e., provenances, seed zones) in the characteristics of tree‐trunk bark in a 17‐year‐old common garden and the associated response of a dependent macroarthropod community. In total, 180 macroarthropod taxa were identified following a collection from 100 trees of five races. We found substantial genetically based variation within E. globulus in the quantity and type of decorticating bark. In the community of organisms associated with this bark, significant variation existed among trees of different races in composition, and there was a two‐fold difference in species richness (7–14 species) and abundance (22–55 individuals) among races. This community variation was tightly linked with genetically based variation in bark, with 60% of variation in community composition driven by bark characteristics. No detectable correlation was found, however, with neutral molecular markers. These community‐level effects of tree genetics are expected to extend to higher trophic levels because of the extensive use of tree trunks as foraging zones by birds and marsupials. Our results demonstrate the potential biodiversity benefits that may be gained through conservation of intraspecific genetic variation within broadly distributed foundation species. The opportunities for enhancing biodiversity values of forestry and restoration plantings are also highlighted because such planted forests are increasingly becoming the dominant forest type in many areas of the world. 相似文献
98.
99.
Molecular methods are useful both to monitor natural communities of bacteria, and to track specific bacterial markers in complex environments. Length-heterogeneity polymerase chain reaction (LH-PCR) and terminal restriction fragment length polymorphism (T-RFLP) of 16S rDNAs discriminate among 16S rRNA genes based on length polymorphisms of their PCR products. With these methods, we developed an alternative indicator that distinguishes the source of fecal pollution in water. We amplify 16S rRNA gene fragments from the fecal anaerobic genus Bacteroides with specific primers. Because Bacteroides normally resides in gut habitats, its presence in water indicates fecal pollution. Molecular detection circumvents the complexities of growing anaerobic bacteria. We identified Bacteroides LH-PCR and T-RFLP ribosomal DNA markers unique to either ruminant or human feces. The same unique fecal markers were recovered from polluted natural waters. We cloned and sequenced the unique markers; marker sequences were used to design specific PCR primers that reliably distinguish human from ruminant sources of fecal contamination. Primers for more species are under development. This approach is more sensitive than fecal coliform assays, is comparable in complexity to standard food safety and public health diagnostic tests, and lends itself to automation and high-throughput. Thus molecular genetic markers for fecal anaerobic bacteria hold promise for monitoring bacterial pollution and water quality. 相似文献
100.
The purpose of this study is to examine the origin, development, and characteristics of terraces (kella), plus their potentials and determinants for sustainable use in the Chencha–Dorze Belle area of southern Ethiopia. Field surveys were conducted to determine the various parameters of the indigenous terraces and in order to collect samples for radiocarbon dating. To identify farmers’ views of the terrace systems, semi-structured interviews and group discussions were also carried out. Terraces were built and used—as radiocarbon dating proves—at least over the last 800 years. The long-term continued usage of the indigenous terraces is the result of social commitments, the structural features of the terraces, and the farmers’ responses to the dynamics of social and cultural circumstances. We dubbed that the terraces are a success story of fruitful environmental management over generations. Thus, a strong need is to preserve and develop this important cultural heritage and example of sustainable land use. 相似文献