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831.
天然气应用对兰州大气环境的影响 总被引:3,自引:0,他引:3
煤烟型污染是兰州市大气污染严重的主要原因之一,西气东输工程对改变兰州市能源结构,改善城市环境质量具有非常重要的意义。根据兰州市大气污染现状和特性,以2000年为基准,分析研究了兰州市利用天然气前后能源结构,主要污染源及大气污染物排放量的变化。针对污染源状况和兰州市天然气用气规划,选用适宜模式预测了兰州市利用天然气后的各主要污染物的年平均浓度,计算了空气质量的改善程度。 相似文献
832.
833.
Despite sustained scholarly interest in post‐conflict states, there has not been a thorough review and analysis of associated methodology and the challenges of conducting research in these contexts. Addressing this gap, this paper directs attention to the particular effects of these settings on access and data quality and their ramifications for the resulting scholarship. It assesses the intrinsic challenges of performing fieldwork in these environments, drawing on both relevant social science literature and the authors’ experiences of carrying out research in Afghanistan and Timor‐Leste. The study demonstrates that the post‐conflict environment moulds research design and, consequently, influences how questions are answered as well as the questions asked. Moreover, it highlights ways to mitigate these issues. This work is of relevance to scholars planning to engage in field research and to researchers reflecting upon their work, as well as to policymakers who are considering undertaking programmes or commissioning research in post‐conflict areas. 相似文献
834.
In this laboratory study different combinations of bed (sand, pebble gravel [gravel], and a mix of sand and gravel) and flow (typical and overtopping) were experimented with to investigate the impact of porous deflectors in flow diversity, water quality, and fish performance in prismatic open channels. Deflectors changed the gradually varied flow to a rapidly varied flow, as a sudden change in the water depth was observed at the deflectors, and this change was large for smooth beds. With the presence of gravel, the scouring near the downstream deflector was almost twice that of the sand bed, and with the scouring at its own upstream deflector, irrespective of whether the flow was typical or overtopping. This behavior was a result of sand mobilization due to shear stress and sand mobilization aided gravel transport. The mixed bed showed less gravel movement compared to the gravel-only bed. The percentage of sediment washed out was minor for all bed scenarios, indicating that sediment transport was local. Relative to the sand bed without deflectors (representing a typical urban canal), deflectors resulted in reduced and improved water quality (in terms of sediment load) for sand, and mixed bed, respectively. The fishes found refuge and were comfortable in the pool areas created by deflectors unlike in channels without deflectors where they showed exhaustion. 相似文献
835.
Air pollution is one of the primary concerns of our society for its effect on human health and the environment. Among the policy measures that can be put in place to limit air pollutant emissions, end-of-pipe technologies and/or regulatory instruments may be implemented through legislative acts. Also, equally important are behavioural measures, requiring citizens’ active involvement. The success of any measure to limit pollutant emissions requires the acceptance by the citizens that, in turn, implies a correct perception of the main pollutant emission drivers. We present here the comparison between the public perception of air pollution sources and the real-world situation through a survey carried out in seven European countries and involving 16 101 respondents. Our study shows a dramatic underestimation of the contribution of the agri-food sector to air pollution. This result is common to all respondents in the seven countries examined and only to a small extent depends on gender, age and socio-economic status of the respondents. 相似文献
836.
杨曼莉 《中国人口.资源与环境》2020,(4):116-124
近年来,收入差距扩大与环境质量恶化成为许多国家同时面临的问题,也让一些经济学家开始思考,这两者之间是否存在关联。继20世纪90年代环境库兹涅茨曲线提出以来,一些研究发现不仅收入的绝对水平会对环境质量产生影响,收入差距对环境质量也有影响。本文对这一课题的理论研究进行了梳理,发现现有理论中收入差距对环境质量的影响途径主要有三条。第一条途径是消费者途径,即收入差距影响着以消费为主的个人经济行为,进一步影响着社会消费总量和消费结构,及其过程中产生的污染总量。第二条途径是企业途径,即认为收入差距的扩大会削弱环保型产品的正外部性,不利于环保技术的创新活动,对未来环境质量的改善产生动态影响。第三条途径是政府途径,即认为收入差距会影响相关的环境政策方式与强度选择;而且在不同的社会政策决策机制下,收入差距对环境政策的影响也是不同的,现有的社会决策机制分析框架主要有两种——权利权重型社会决策规则和简单多数规则。此外,本文还对现存的主要实证研究进行了总结,发现大多数研究结论都支持收入差距对环境质量存在着影响,但这种影响并不是线性的。一方面,收入差距对环境的影响与研究的污染物种类有关,大多数研究都显示,收入不平等对CO 2排放和土壤污染存在着负向影响,但有关收入差距对空气污染和水污染影响的研究结论并不统一或并不显著。另一方面,这种影响还与经济发展水平相关,在高收入国家与低收入国家是不同的,存在着阈值效应。最后本文总结了针对中国的研究现状,讨论了其在我国的适用性。 相似文献
837.
Yun-Ya Fang Chien-Yuan Huang 《International journal of occupational safety and ergonomics》2019,25(4):621-629
Introduction. This study aimed to examine the effectiveness of a physical activity (PA) program on weight control, physical fitness, occupational stress, job satisfaction and quality of life of overweight and sedentary employees in high-tech industries. Methods. Participants in the intervention group (n?=?37) were instructed to carry out a PA program at moderate intensity for 60?min/session, 3 sessions/week for 12 weeks. Those in the control group (n?=?38) received no PA program and were asked to continue their routine lifestyle. Evaluations were performed at baseline and at the end of the intervention. Results of structured questionnaires and blood biochemistry tests and evaluations of physical fitness were analyzed. Results. The PA program effectively reduced the number of risk factors for metabolic syndrome and body fat percentage, and improved physical fitness such as flexibility, muscular strength and endurance and cardiorespiratory endurance. The intervention also significantly decreased levels of serum triglyceride, total cholesterol and low-density lipoprotein cholesterol. Significant positive effects on work control, interpersonal relationships at work, global job satisfaction and quality of life were also demonstrated. Conclusion. This study showed that a PA program can be helpful in improving physical, physiological and psychological outcomes for overweight and sedentary employees in high-tech industries. 相似文献
838.
蔬菜施不同肥料对产量和土壤肥力的贡献 总被引:8,自引:2,他引:8
为控制施肥对蔬菜和土壤的负面影响,充分利用施肥对土壤肥力的保护功能,探讨蔬菜合理的有机肥施用量,在不同质地土壤上,田间试验小白菜、苦瓜、豇豆三种蔬菜施不同量有机肥,收获时测定其产量、品质及试验前后的土壤有机质质量分数。结果表明,(1)在施适量无机NPK的条件下,每造蔬菜的有机肥(禽畜粪便,下同)施用量,砂土上小白菜为4500kg/hm^2、苦瓜和豇豆为3000kg/hm^2;在壤土上,小白菜和苦瓜均宜施3000kg/hm^2,豇豆则宜施4500kg/hm^2;在粘土上,小白菜每造只宜施1500~3000kg/hm^2的有机肥。(2)有机肥必须与无机肥合理配合施用,才能获得最佳的产量和品质效果。(3)施有机肥3000-4500kg/hm^2 适量无机肥可使土壤有机质水平保持在种植蔬菜前的质量分数水平,该施肥量和方式不仅可使蔬菜高产、优质,还有利于保护土壤肥力。(4)对蔬菜产量的贡献,有机肥和化肥配合施用的处理对蔬菜产量的贡献最大,来自土壤的效应由小到大依次为有机肥和化肥配合施用→化肥→有机肥,进一步反映合理施肥有利于保护土壤肥力。 相似文献
839.
阎伍玖 《生态与农村环境学报》1994,(3)
本文简要分析了环境质量评价中目前广泛应用的各种评价方法与模型。在此基础上提出环境质量综合评判-灰色关联优势分析复合模型,应用于黄山风景区景观生态环境质量的综合评价,取得了满意的结果。 相似文献
840.