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51.
氧化亚氮在森林和草原中的地-气交换   总被引:13,自引:1,他引:13  
采用箱式法,建立了一套完整的测定森林草原土壤N2O排放方法,并对我国北方的自然环境中N2O排放作了观测,得出其最大排放通量为23μg/(m^2·h)。并发现森林草原土壤当温度低于15℃时对N2O有吸收行为,其最大吸收通量为18.984μg(m^2·h)。  相似文献   
52.
Forty-eight air-filter samples (PM10) were analysed to identify the concentration level of partially leached metals (PLMs; As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and V) from Puebla City, México. Samples were collected during 2008 from four monitoring sites: (1) Tecnológico (TEC), (2) Ninfas (NIN), (3) Hermanos Serdán (HS) and (4) Agua Santa (AS). The results indicate that in TEC, As (avg. 424 ng m?3), V (avg. 19.2 ng m?3), Fe (avg. 1,202 ng m?3), Cu (avg. 86.6 ng m?3), Cr (41.9 ng m?3) and Ni (18.6 ng m?3) are on the higher side than other populated regions around the world. The enrichment of PLMs is due to the industrial complexes generating huge dust particles involving various operations. The results are supported by the correlation of metals (Mn, Cd and Co) with Fe indicating its anthropogenic origin and likewise, As with Cd, Co, Fe, Mn, Pb and V. The separate cluster of As, Fe and Mn clearly signifies that it is due to continuous eruption of fumaroles from the active volcano Popocatépetl in the region.  相似文献   
53.
The measurements of atmospheric carbonyls concentrations in Beijing were conducted from 12 July to 8 October, 2008, covering the periods of the 2008 Olympic Games and Paralympic Games. Six carbonyls, including formaldehyde, acetaldehyde, acetone, butyraldehyde, valeraldehyde, and hexaldehyde, were identified in all air samples. The total average concentrations of these carbonyls before, during, and after traffic restriction were (48.1 ± 15.2), (36.6 ± 14.5) and (23.4 ± 12.3) μg/m3, respectively. Compared with the period after traffic restriction, the distinct high concentrations of the carbonyls before and during traffic restriction were primarily ascribed to the remarkable contribution of photochemical reactions. With respect to our previous investigation in the summer of 2005, the reductions of formaldehyde, acetaldehyde and acetone during traffic restriction period were about 64%, 47% and 27%, respectively, indicating that the air cleaning actions adopted by the Chinese government for the two games were efficient. The lowest levels of atmospheric carbonyls and the extremely high composition proportion of acetone after the traffic restriction were mainly attributed to the long-term effect of the control measures for the two games.  相似文献   
54.
图书馆藏书大多存在实物与财产登记不符的状况,如情况较为严重则会影响到图书馆流通、采访等项工作的开展,因此适时进行书库清点具有重要意义。本文以中国环境管理干部学院图书馆的清点为实例,初步探讨了将条码作为清点切入点的书库清点工作的方法、步骤和注意事项。  相似文献   
55.
室内外空气污染暴露评价   总被引:13,自引:0,他引:13  
介绍了国外对室内外空气污染暴露评价的各种方法,并运用微环境结合问卷调查的方法,选择了5种主要的空气污染物;甲醛、二氧化硫、氮氧化物,氮和氡作为检测评价的对象,初步评价了北京市各年龄层次人群的污染物暴露水平。结果表明,大部分暴露量源于室内环境,尤其是工作(或学习)场所及住宅;各年龄层次人群的甲醛日平均暴露量均超过相关环境标准,而其它污染物均不超标;室内空气污染特别是因装修引起的室内空气污染应得到重视。  相似文献   
56.
模拟酸雨对砂浆的强度、物相和孔结构影响的研究   总被引:21,自引:0,他引:21  
  相似文献   
57.
Long term lead metabolism in the human body has never been fully understood due to the lack of human data in this area. The technological improvement of bone lead measurement systems has made bone lead data of substantial populations available. In this study, a set of X-ray fluorescence bone lead data was used to test Leggett's lead metabolism model (R. W. Leggett, Environ. Health Perspect., 1993a, 101, 598-616), especially the model of metabolism in bone. The data set includes the bone lead concentration of 539 occupationally exposed workers, of whom 327 were measured twice in five years. The bone lead concentrations of both cortical bone (tibia) and trabecular bone (calcaneus) were obtained by Cd-109 gamma-ray induced XRF measurement. The histories of blood lead concentration for these workers were used to regulate the input file of the model. The results show that the bone lead concentrations predicted by Leggett's model greatly underestimate the measured values, especially for older workers. This data set was then organized into five age groups. A new simplified model was applied to estimate the lead transfer rates between blood and lead compartments for these age groups. The original transfer rates and the new transfer rates are compared, and the differences are discussed. When the transfer rates derived from measured bone lead data were put into the input file of the model to replace the existing parameters, the predicted values were much closer to the measured values for both cortical bone and trabecular bone.  相似文献   
58.
Interdisciplinarity is needed to gain knowledge of the ecology of invasive species and invaded ecosystems, and of the human dimensions of biological invasions. We combine a quantitative literature review with a qualitative historical narrative to document the progress of interdisciplinarity in invasion science since 1950. Our review shows that 92.4% of interdisciplinary publications (out of 9192) focus on ecological questions, 4.4% on social ones, and 3.2% on socialecological ones. The emergence of invasion science out of ecology might explain why interdisciplinarity has remained mostly within the natural sciences. Nevertheless, invasion science is attracting social–ecological collaborations to understand ecological challenges, and to develop novel approaches to address new ideas, concepts, and invasion-related questions between scholars and stakeholders. We discuss ways to reframe invasion science as a field centred on interlinked social–ecological dynamics to bring science, governance and society together in a common effort to deal with invasions.  相似文献   
59.
Human pressure has been exponentially growing during recent decades in coastal areas, which have led to drastic losses of biodiversity in coastal ecosystems. The current conservation status of many coastal plant species is directly related to a lack of environmental criteria in the urban planning of coastal areas over recent decades. This study aimed to evaluate the evolution, over the last 9 years, of the conservation status of various populations of the endangered plant Glaucium flavum, exploring the extent to which human pressure and different management strategies practiced in the coastal areas where the populations are established have affected the conservation status of the species. The populations analysed have evolved in a different manner over the last 9 years, as have their threat factors, and a relationship was evident between their conservation status and the evolution of these different threat factors. Our results indicate that an appropriate planning of local management actions, such as the installation of walkways or the successful eradication of invasive species, may be determinant factors for successful conservation of the coastal vegetation. The presence of species that are sensitive to slight changes in the ecosystem, and the main factors that govern the plant performance of these species, must be given full consideration in decision-making processes of coastal planning and management.  相似文献   
60.
中国大洋第19航次科学考察队的“大洋一号”科学考察船在西南印度洋脊发现了新的海底热液活动区.确定了热液喷口位置.并在东南印度洋中脊发现新的海底热液异常区。这是我国科学家第一次也是世界上首次在西南印度洋中脊和超慢速扩张洋中脊发现正在活动  相似文献   
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