新形势下环境质量综合分析思路探讨

随着中国共产党第十九次全国代表大会的顺利召开,环保"大部制"改革、环境监测垂直管理制度改革以及国家"大气十条""水十条""土十条"的全面实施均对生态环境保护、环境监测乃至环境质量综合分析工作提出了新要求。新形势下,环境质量综合分析应与时俱进、开拓创新,进一步优化工作机制,加强系统分析,增强综合分析报告的科学性、规范性、时效性、精准性、客观性等,强化技术与能力支撑,更好发挥环境监测对环境管理和决策的引领作用。     

氢安全研究现状及面临的挑战

氢能具有储运便捷、来源多样、洁净环保等突出优点,许多国家把发展氢能作为重要的能源战略。氢安全是氢能大规模商业化应用的重要保障。在分析国内外氢安全领域近年来最新研究进展的基础上,依次从氢泄漏与扩散、氢燃烧与爆炸、氢与金属材料相容性及氢风险评价等方面,系统总结了国内外氢安全研究面临的挑战,并对我国氢安全的发展提出了建议。     

Impact of leakage location and downwind storage tank on the gas dispersion in a typical chemical tank storage area

Toxic gas leakage in a tank area can have catastrophic consequences. Storage tank leakage location (particularly for high leakage) and downwind storage tanks potentially influence gas diffusion in tank areas. In this study, we developed a numerical and experimental method to investigate the impact of a high leakage location and downwind storage tank on gas diffusion based on three (1.05H, 0.90H, and 0.77H, H was the tank height, 22m) leakage field experiments on the leeward side of storage tank, which have been not conducted before. The experiments revealed an unexpected phenomenon: the maximum ground concentration first decreased and then increased with increasing leakage height. The simulations illustrated that the differences in micrometeorological conditions caused the maximum ground concentration of gas emitted from the roof to be higher than that emitted from the tank wall near the storage tank height. The downwind storage tank 1) had little influence on the entire diffusion direction but altered the local diffusion pattern; 2) reduced the maximum ground concentration (∼18.7%) and the distance from the emission source (approximately a storage tank diameter); and 3) had strong influences on the concentration, velocity, turbulence, and pressure on the leeward side. The concentration negatively correlated with the velocity, pressure, and turbulence in the middle of the two storage tanks on wind centerline. Our results can improve understanding of gas dispersion in tank areas and provide references for mitigating loss and protecting lives during emergency response processes.     

西安市PM_(2.5)污染源位置确定的模型应用研究

针对空气中PM2.5污染物的传播问题,以西安市的情况为实例,合理考虑风力等天气和季节因素的影响,建立能够刻画该地区PM2.5的发生和演变规律的有风高斯点源扩散数学模型,代入相关数据后,利用MATLAB软件求解出PM2.5污染源由一区扩散到另一区的浓度,最后由综合的各区总浓度得出PM2.5污染源的位置,并与该市实际检测到PM2.5数据进行对比分析。结果表明,确定的位置比较准确,该方法能为城市污染治理提供参考。     

Reduction and characterization of bioaerosols in a wastewater treatment station via ventilation

Bioaerosols from wastewater treatment processes are a significant subgroup of atmospheric aerosols. In the present study,airborne microorganisms generated from a wastewater treatment station(WWTS) that uses an oxidation ditch process were diminished by ventilation.Conventional sampling and detection methods combined with cloning/sequencing techniques were applied to determine the groups,concentrations,size distributions,and species diversity of airborne microorganisms before and after ventilation. There were 3021 ± 537 CFU/m3 of airborne bacteria and 926 ± 132 CFU/m3 of airborne fungi present in the WWTS bioaerosol.Results showed that the ventilation reduced airborne microorganisms significantly compared to the air in the WWTS. Over 60% of airborne bacteria and airborne fungi could be reduced after4 hr of air exchange. The highest removal(92.1% for airborne bacteria and 89.1% for fungi) was achieved for 0.65–1.1 μm sized particles. The bioaerosol particles over 4.7 μm were also reduced effectively. Large particles tended to be lost by gravitational settling and small particles were generally carried away,which led to the relatively easy reduction of bioaerosol particles0.65–1.1 μm and over 4.7 μm in size. An obvious variation occurred in the structure of the bacterial communities when ventilation was applied to control the airborne microorganisms in enclosed spaces.     

基于情景信息扩散模型的雾霾社会风险演化仿真研究

雾霾灾害不仅危害公众健康,且风险信息的传播会引发社会次级风险。为了研究社会风险信息的扩散演化趋势,本文构建了雾霾社会风险的情景信息扩散模型。以中国2013年雾霾灾害为例,将风险信息扩散过程分为爆发期、扩散期和稳定期,分析了不同参数条件下的信息扩散规律。结果表明,政府应在风险信息爆发期和扩散期增大官方渠道信息的覆盖范围,尤其在爆发期需对自由渠道发布的信息进行严格监管,在社会风险扩大之前制定应对策略。     

Model of chloride ingress into concrete in cold regions

Chloride ingress and freeze-thaw cycles are the most important mechanisms for deterioration of concrete in cold areas. In this study, chloride ingress into concrete that has been exposed to freeze-thaw cycles was investigated. Data demonstrated that freeze-thaw cycles allow for a larger effective diffusion coefficient. Based on our findings, the concept of a developing coefficient was defined to obtain the evolution equation of the effective diffusion coefficient. Together with considering the effect of aging of concrete on the effective diffusion coefficient, the time-dependent diffusion coefficient was also obtained. Based on Fick's second law and time-dependent diffusion coefficient, chloride ingress model of concrete in cold regions was derived. Finally, the model was tested by comparing predicted results, lab results, and in situ inspection data.     

Did Child Restraint Laws Globally Converge? Examining 40 Years of Policy Diffusion

Objective: The objective of the current study is to determine what factors have been associated with the global adoption of mandatory child restraint laws (ChRLs) since 1975.

Methods: In order to determine what factors explained the global adoption of mandatory ChRLs, Weibull models were analyzed. To carry out this analysis, 170 countries were considered and the time risk corresponded to 5,146 observations for the period 1957–2013. The dependent variable was first time to adopt a ChRL. Independent variables representing global factors were the World Health Organization (WHO) and World Bank's (WB) road safety global campaign; the Geneva Convention on Road Traffic; and the United Nation's (UN) 1958 Vehicle Agreement. Independent variables representing regional factors were the creation of the European Transport Safety Council and being a Commonwealth country. Independent variables representing national factors were population; gross domestic product (GDP) per capita; political violence; existence of road safety nongovernmental organizations (NGOs); and existence of road safety agencies. Urbanization served as a control variable. To examine regional dynamics, Weibull models for Africa, Asia, Europe, North America, Latin America, the Caribbean, and the Commonwealth were also carried out.

Results: Empirical estimates from full Weibull models suggest that 2 global factors and 2 national factors are significantly associated with the adoption of this measure. The global factors explaining adoption are the WHO and WB's road safety global campaign implemented after 2004 (P <.01), and the UN's 1958 Vehicle Agreement (P <.001). National factors were GDP (P <.01) and existence of road safety agencies (P <.05). The time parameter ρ for the full Weibull model was 1.425 (P <.001), suggesting that the likelihood of ChRL adoption increased over the observed period of time, confirming that the diffusion of this policy was global. Regional analysis showed that the UN's Convention on Road Traffic was significant in Asia, the creation of the European Transport Safety Council was significant in Europe and North America, and the global campaign was in Africa. In Commonwealth and European and North American countries, the existence of road safety agencies was also positively associated with ChRL adoption.

Conclusions: Results of the world models suggest that the WHO and WB's global road safety campaign was effective in disseminating ChRLs after 2004. Furthermore, regions such as Asia and Europe and North America were early adopters since specific regional and national characteristics anticipated the introduction of this policy before 2004. In this particular case, the creation of the European Transport Safety Council was fundamental in promoting ChRLs. Thus, in order to introduce conditions to more rapidly diffuse road safety measures across lagging regions, the maintenance of global efforts and the creation of road safety regional organizations should be encouraged. Lastly, the case of ChRL convergence illustrates how mechanisms of global and regional diffusion need to be analytically differentiated in order better to assess the process of policy diffusion.     

Vallisneria natans decomposition rates and associated macroinvertebrates,microbes and microalgae along a vertical depth gradient in an urban lake (Nanhu Lake,China)

Knowledge on aquatic macrophyte decomposition has well developed, yet the decomposition and associated biotic factors along a vertical gradient in waters remain less examined. Here, we used Vallianeria natans leaves to investigate the decomposition rate and associated decomposers and microalgae at different vertical depths, by placing V. natans leaves into litterbags (0.5 and 5?mm meshes) and incubating them at the air–water interface (AW), sediment-water (SW) interface, and 10?cm (B10) or 20?cm (B20) burial in sediment over 60 days in a littoral zone of lake. Decomposition rates decreased with increased depths in each mesh size, with significant differences among and between AW (0.028?d^?1), SW (0.022?d^?1), B10 (0.014?d^?1) and B20 (0.011?d^?1) treatments in 0.5?mm litterbags and no significant difference between B10 (0.027?d^?1) and B20 (0.025?d^?1) in 5?mm litterbags. The average contribution of macroinvertebrates to biomass loss was highest in B20 (44.66%), lowest in AW (22.66%) and midst in both SW (25.35%) and B10 (38.78%), and was much less than that of both microbes and microalgae at each location. We show the importance of macroinvertebrates, microbes and microalgae in mediating macrophyte decomposition rate in response to different vertical locations in freshwaters.     

中国低碳城市试点的政策设计逻辑

政策试点是中国国家治理策略体系的重要组成部分,是中国政府遵循“由点到面”逻辑以试验手段制定政策的一种常规性工作方法。低碳城市试点是中国应对气候变化战略的重要组成部分,通过选择不同类型、不同发展阶段、不同资源禀赋的地区开展试点,探索经济增长与碳排放脱钩的模式。现有文献侧重低碳城市建设的内涵、建设模式与路径、温室气体的核算方法、政策手段、峰值研究与达峰路径、效果评估等,有力地支持了低碳城市建设决策,但对于低碳城市试点的政策设计鲜有涉及。本文从政策过程理论、央地关系两个视角,结合府际学习与竞争关系,建构了中国低碳城市政策“试点–扩散”机制与政府行为的分析框架。中国的低碳城市试点具有探索型开拓性、综合型专业性、授权型自主性的特点,结合三批低碳城市试点的文件要求和实践进展,从政策试点的选点、设计、执行、监督和评估五个方面对于中国低碳城市试点进行了系统的梳理分析。相较于经济领域的其他政策试点,低碳城市政策试点具有弱激励弱约束的政策环境。地方政府基于自身的学习能力和领导力,在政策创新方面表现出争先、自主、效仿和守成四种行为特征,并以杭州、深圳、镇江、成都四个表率城市做了实证。政策“试点-扩散”的过程从本质上讲是中国政策创新与扩散的过程,可能在现实中需要往复多次进行,中国已陆续开展的三批低碳城市试点工作就遵循这样的政策逻辑。试点的意义是试出问题、解决问题、积累经验。从前三批试点城市评估结果来看,试点城市在低碳发展目标设定、转型路径探索和低碳发展动力转换等方面与社会的预期仍有差距,为此本文提出了推进低碳城市建设的四点建议:一是激发城市低碳发展的内生动力;二是完善低碳城市试点的科学论证机制;三是建立激励与约束并举的长效机制;四是强化市场公平竞争的政策导向。