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排序方式: 共有3397条查询结果,搜索用时 15 毫秒
991.
Pitkänen T Karinen P Miettinen IT Lettojärvi H Heikkilä A Maunula R Aula V Kuronen H Vepsäläinen A Nousiainen LL Pelkonen S Heinonen-Tanski H 《Ambio》2011,40(4):377-390
The raw water quality and associations between the factors considered as threats to water safety were studied in 20 groundwater supplies in central Finland in 2002-2004. Faecal contaminations indicated by the appearance of Escherichia coli or intestinal enterococci were present in five small community water supplies, all these managed by local water cooperatives. Elevated concentrations of nutrients in raw water were linked with the presence of faecal bacteria. The presence of on-site technical hazards to water safety, such as inadequate well construction and maintenance enabling surface water to enter into the well and the insufficient depth of protective soil layers above the groundwater table, showed the vulnerability of the quality of groundwater used for drinking purposes. To minimize the risk of waterborne illnesses, the vulnerable water supplies need to be identified and appropriate prevention measures such as disinfection should be applied. 相似文献
992.
不同菌剂处理下猪粪和牛粪堆肥前期性质变化 总被引:1,自引:0,他引:1
以猪粪和牛粪为堆肥原料,设计了人工接种MixF-3菌剂堆肥、添加灭活菌剂堆肥和自然堆肥3个处理进行堆肥前期实验,探讨堆肥9d过程中温度、水分、有机碳、全氮和微生物量碳等参数的变化。结果表明,按1L/t接种MixF-3混合菌剂堆肥温度升温快,猪粪堆肥第48h和第84h时温度分别达到66℃和71.5℃,牛粪堆肥第48h时温度达69℃,明显高于灭活菌剂处理组和CK对照组。随着堆肥的进行,各处理组水分含量缓慢下降,牛粪比猪粪含水量略高。人工接种菌剂的猪粪和牛粪堆肥处理组中pH变化幅度小,有机碳碳含量的下降幅度比灭活组和自然堆肥组大,分别下降15.64%和11.25%,全氮含量缓慢升高但变化不大,人工接种牛粪比猪粪处理组中堆肥全氮含量升幅高;在猪粪和牛粪堆肥中人工接种菌剂微生物量碳降幅最小,分别为9537μg/g和3212μg/g,表明在猪粪和牛粪堆肥原料中添加MixF-3复合菌剂有利于微生物繁殖生长,同时拓宽了菌剂使用的单一性,更具有普遍性意义。 相似文献
993.
Monitoring of the microbial community composition in saline aquifers during CO2 storage by fluorescence in situ hybridisation 总被引:1,自引:0,他引:1
Daria Morozova Maren Wandrey Mashal Alawi Martin Zimmer Andrea Vieth Michael Zettlitzer Hilke Würdemann the COSINK Group 《International Journal of Greenhouse Gas Control》2010,4(6):981-989
This study reveals the first analyses of the composition and activity of the microbial community of a saline CO2 storage aquifer. Microbial monitoring during CO2 injection has been reported. By using fluorescence in situ hybridisation (FISH), we have shown that the microbial community was strongly influenced by the CO2 injection. Before CO2 arrival, up to 6 × 106 cells ml−1 were detected by DAPI staining at a depth of 647 m below the surface. The microbial community was dominated by the domain Bacteria that represented approximately 60% to 90% of the total cell number, with Proteobacteria and Firmicutes as the most abundant phyla comprising up to 47% and 45% of the entire population, respectively. Both the total cell counts as well as the counts of the specific physiological groups revealed quantitative and qualitative changes after CO2 arrival. Our study revealed temporal outcompetition of sulphate-reducing bacteria by methanogenic archaea. In addition, an enhanced activity of the microbial population after five months CO2 storage indicated that the bacterial community was able to adapt to the extreme conditions of the deep biosphere and to the extreme changes of these atypical conditions. 相似文献
994.
聚合酶链反应—变性梯度凝胶电泳技术研究梯田式人工湿地微生物群落动态变化 总被引:1,自引:0,他引:1
采用聚合酶链反应(PCR)—变性梯度凝胶电泳(DGGE)技术对梯田式人工湿地(TTCW)和复合垂直流式人工湿地(IVCW)生活污水处理系统内的微生物群落结构的动态变化及其对生活污水处理效果的影响进行了对比研究。结果表明:(1)TTCW和IVCW对生活污水均具有较好处理效果,其COD去除率平均分别为76.2%和72.6%、TP去除率平均分别为90.7%和85.6%、NH4+-N去除率平均分别为65.2%和58.8%;TTCW增氧作用明显。(2)2种人工湿地内均存在丰富的微生物群落,并均存在共有的微生物种群;在湿地沿程不同位置均存在一定数量的优势种群。(3)TTCW强化了大气复氧能力,使得湿地内DO较相同深度的IVCW的高。TTCW具有较强的污染物去除能力,特别是具有高效的脱氮除磷能力。这种能力可能主要是TTCW中微生物群落结构的变化所致。 相似文献
995.
Abella SR 《Environmental management》2008,41(6):809-819
Wild burros (Equus asinus), protected by the 1971 Wild Free-Roaming Horse and Burro Act on some federal lands but exotic animals many ecologists and
resource mangers view as damaging to native ecosystems, represent one of the most contentious environmental management problems
in American Southwest arid lands. This review synthesizes the scattered literature about burro effects on plant communities
of the Mojave Desert, a center of burro management contentions. I classified 24 documents meeting selection criteria for this
review into five categories of research: (i) diet analyses directly determining which plant species burros consume, (ii) utilization
studies of individual species, (iii) control-impact comparisons, (iv) exclosure studies, and (v) forage analyses examining
chemical characteristics of forage plants. Ten diet studies recorded 175 total species that burros consumed. However, these
studies and two exclosure studies suggested that burros preferentially eat graminoid and forb groups over shrubs. One study
in Death Valley National Park, for example, found that Achnatherum hymenoides (Indian ricegrass) was 11 times more abundant in burro diets than expected based on its availability. Utilization studies
revealed that burros also exhibit preferences within the shrub group. Eighty-three percent of reviewed documents were produced
in a 12-year period, from 1972 to 1983, with the most recent document produced in 1988. Because burros remain abundant on
many federal lands and grazing may interact with other management concerns (e.g., desert wildfires fueled by exotic grasses),
rejuvenating grazing research to better understand both past and present burro effects could help guide revegetation and grazing
management scenarios. 相似文献
996.
Rocky intertidal habitats frequently are used by humans for recreational, educational, and subsistence-harvesting purposes,
with intertidal populations damaged by visitation activities such as extraction, trampling, and handling. California Marine
Managed Areas, particularly regulatory marine reserves (MRs), were established to provide legal protection and enhancement
of coastal resources and include prohibitions on harvesting intertidal populations. However, the effectiveness of MRs is unclear
as enforcement of no-take laws is weak and no regulations protect intertidal species from other detrimental visitor impacts
such as trampling. The goal of this study was two-fold: (1) to determine impacts from human visitation on California mussel
populations (Mytilus californianus) and mussel bed community diversity; and (2) to investigate the effectiveness of regulatory MRs in reducing visitor impacts
on these populations. Surveys of mussel populations and bed-associated diversity were compared: (1) at sites subjected to
either high or low levels of human use, and (2) at sites either unprotected or with regulatory protection banning collecting.
At sites subjected to higher levels of human visitation, mussel populations were significantly lower than low-use sites. Comparisons
of mussel populations inside and outside of regulatory MRs revealed no consistent pattern suggesting that California no-take
regulatory reserves may have limited effectiveness in protecting mussel communities. In areas where many people visit intertidal
habitats for purposes other than collecting, many organisms will be affected by trampling, turning of rocks, and handling.
In these cases, effective protection of rocky intertidal communities requires an approach that goes beyond the singular focus
on collecting to reduce the full suite of impacts. 相似文献
997.
The US Army Corps of Engineers often requires wetland creation or restoration as compensation for wetlands damaged during
development. These wetlands are typically monitored postconstruction to determine the level of compliance with respect to
site-specific performance standards. However, defining appropriate goals and measuring success of restorations has proven
difficult. We reviewed monitoring information for 76 wetlands constructed between 1992 and 2002 to summarize the performance
criteria used to measure progress, assess compliance with those criteria, and, finally, to evaluate the appropriateness of
those criteria. Goals were overwhelmingly focused on plant communities. Attributes used to assess the quality of restored
plant communities, including percent native species and the Floristic Quality Index, increased over time but were apparently
unrelated to the number of species planted. Compliance frequencies varied depending on site goals; sites often failed to comply
with criteria related to survival of planted vegetation or requirements that dominant plant species should not be exotic or
weedy, whereas criteria related to the establishment of cover by vegetation or by wetland-dependent plants were often met.
Judgment of a site’s success or failure was largely a function of the goals set for the site. Some performance criteria were
too lenient to be of value in distinguishing failed from successful sites, whereas other criteria were unachievable without
more intensive site management. More appropriate goals could be devised for restored wetlands by basing performance standards
on past performance of similar restorations, identifying consistent temporal trends in attributes of restored sites, and using
natural wetlands as references. 相似文献
998.
城市社区防灾减灾工作机制研究 总被引:1,自引:0,他引:1
在组织论指导下,提出在区民防办下设街道防减灾办公室,负责社区防减灾的领导工作。根据灾害管理过程,设置下属机构包括:社区灾害预防组、应急救援组和灾后恢复组。明确各相关方在具体工作中的角色和责任,完善社区防减灾机制。按自愿原则组建志愿者队伍,建立良好的培养和激励机制,确保服务人员的长期化。扩大基层防减灾宣传教育的广度,特别是基层领导干部和青少年的宣教。将宣教和防灾演练结合,使得防灾演练制度化。同时,需要重视在现有"120"急救网络上,建立院前急救体系,配备相应的物资和人员。 相似文献
999.
Performance and Environmental Impact of Biodegradable Films in Agriculture: A Field Study on Protected Cultivation 总被引:5,自引:1,他引:4
Anu Kapanen Evelia Schettini Giuliano Vox Merja Itävaara 《Journal of Polymers and the Environment》2008,16(2):109-122
The performance, the degradability in soil and the environmental impact of biodegradable starch-based soil mulching and low
tunnel films were assessed by means of field and laboratory tests. The lifetime of the biodegradable mulches was 9 months
and of the biodegradable low-tunnel films 6 months. The radiometric properties of the biodegradable films influenced positively
the microclimate: air temperature under the biodegradable low tunnel films was 2 °C higher than under the low density polyethylene
films, resulting in an up to 20% higher yield of strawberries. At the end of the cultivation period, the biodegradable mulches
were broken up and buried in the field soil together with the plant residues. One year after burial, less than 4% of the initial
weight of the biodegradable film was found in the soil. According to ecotoxicity tests, the kinetic luminescent bacteria test
with Vibrio fischeri and the Enchytraeus albidus ISO/CD 16387 reproduction potential, there was no evidence of ecotoxicity in the soil during the biodegradation process.
Furthermore, there was no change in the diversity of ammonia-oxidizing bacteria in the soil determined on the basis of the
appearance of amoA gene diversity in denaturing gradient gel electrophoresis. 相似文献
1000.
以好氧颗粒污泥为接种污泥,通过全氟辛烷磺酸(PFOS)长期驯化实现耐PFOS颗粒的培养,考察不同驯化时期的污泥基本特性,并结合微生物群落演替过程、微生物表型分布以及功能途径的变化情况,以揭示其耐受机制.结果表明,好氧颗粒污泥经历解体、再形成和成熟3个阶段后可在PFOS暴露下稳定维持.驯化成熟后的好氧颗粒污泥表面丝状菌减少,并且被大量胞外聚合物(EPS)所包裹,结构更加致密.驯化期间颗粒污泥中存在大量抗性细菌以及维持颗粒稳定相关细菌,主要包括unclassified_f__Comamonadaceae、Defluviicoccus、Dongia、Rhodoplanes、Flavobacterium、Thauera、Azospira、Candidatus_Competibacter、Azoarcus和norank_f__A4b,且部分菌属间存在显著的正相关性.群体感应途径和细菌趋化途径相关基因丰度在解体期上调,在颗粒形成和成熟期恢复至初始水平,说明细菌的群体感应效应和趋化性能够在颗粒应激过程中起重要作用.因此,好氧颗粒污泥可以通过特定菌群积极响应、促进细菌趋化作用和群体感应作用、提高EPS... 相似文献