Does new-type urbanization curb haze pollution? A case study from China

Environmental Science and Pollution Research - The rapid urbanization process has led to a high concentration of population and economic activities in urban space, thus leading to severe...     

Premixed methane-air deflagrations in a completely adiabatic pipe and the effect of the condition of the pipe wall

A completely adiabatic pipe that is similar to a coal-mine coal or rock roadway was simulated using the computational software AutoReaGas. A partially adiabatic pipe was established using an experimental steel pipe with heat-insulating material installed in the inner wall, and a non-adiabatic pipe was also established using the experimental steel pipe without the heat-insulating material. Premixed methane/air deflagrations were studied in the three types of pipe to reveal the influence of the condition of the pipe wall on gas explosions. The results showed that in the completely adiabatic pipe, the maximum explosion overpressure was dynamic and decreased and increased with increasing distance; however, the flame-propagation speed increased gradually. In the partially adiabatic pipe and the non-adiabatic pipe, the maximum explosion overpressure and flame-propagation speed increased initially and then gradually decreased with increasing distance. The majority of explosion overpressure and flame-propagation speed values at each gauge in the completely adiabatic pipe were larger than those of the partially adiabatic pipe. Both measurements at each gauge in the partially adiabatic pipe were much greater than those of the non-adiabatic pipe. The condition of the pipe wall has a large influence on the maximum explosion overpressure and the flame-propagation speed. In future explosion experiments, heat insulating materials should be installed in the inner wall of steel pipes to obtain data for application to the prevention and control of gas explosions in underground coal mines.     

因子分析法在污染源解析方面的应用

针对长春市存在污染的46个土壤采样点,以Hg、Cd、Pb、As、Cu、Cr、Zn七种重金属元素指标作因子分析,从而为长春市表层土壤重金属污染成因的解释提供一定的理论依据。     

Removal of Pb(II) from aqueous solution by hydrous manganese dioxide: Adsorption behavior and mechanism

Hydrous manganese dioxide (HMO) synthesized by redox of potassium permanganate and hydrogen peroxide was used as an adsorbent for Pb(Ⅱ) removal.The specific surface area,pore volume and BJH pore diameter of the HMO were 79.31m2/g,0.07cm3/g and 3.38 nm,respectively.The adsorption equilibrium at 298K could be well described by the Langmuir isotherm equation with q max value of 352.55mg/g.The negative values of G and the positive values of H and S indicated the adsorption process was spontaneous and endothermic.The pseudo second-order equation could best fit the adsorption data.The value of the calculated activation energy for Pb(Ⅱ) adsorption onto the HMO was 38.23 kJ/mol.The uptake of Pb(Ⅱ) by HMO was correlated with increasing surface hydroxyl group content and the main adsorbed speciation was PbOH+.The final chemical state of Pb(Ⅱ) on the surface of HMO was similar to PbO.HMO was a promising candidate for Pb(Ⅱ) removal from aqueous solution.     

重庆大气中臭氧浓度变化及其前体物的相关性分析

臭氧是城市光化学烟雾的主要成分,同时也是重要的温室气体,因此臭氧污染已经成为城市空气质量的重要因素。利用近几年臭氧连续监测的数据,对臭氧的浓度变化特征进行了分析,并且对臭氧前体物（NOx、NOy、VOCs等）和气象因素作了相关性分析。结果表示臭氧浓度呈典型的季节性变化趋势,并且小时值变化出现明显的日变化规律,与太阳辐射强度成正相关;另外VOCs（挥发性有机物）与臭氧的变化规律基本一致,同时与NOx、NOy的浓度变化趋势存在较好的负相关性。     

数字水印技术在古典家具数字博物馆版权保护中的研究

近年来,古典家具越来越受到人们的青睐。但是目前还未见有关针对古典文物家具数字博物馆的相关研究报道。本文首先介绍了数字博物馆的特点以及所构建的明清古典文物家具数字博物馆,然后运用基于混沌理论的Logistic映射置乱方法对水印图像进行加密,以及变换域算法中基于DCT域的数字水印方法对数字博物馆的数字图像进行了版权保护,并利用Matlab软件进行水印图像的嵌入、提取和检测实验,取得了较好的效果,说明数字水印技术在文物家具图像版权保护方面具有很好的作用。     

我国中小城镇污水治理现状

随着近几年中小城市发展进程的加快,城市中日益暴露出各方面的问题与弊端,污水治理问题显得尤为突出和严重。污水排放大量增加对我国中小城市水环境造成了严重的污染和破坏,因此对污水处理技术的选择与考量十分迫切。基于我国国情,我国是发展中国家,财力有限。因此用于基础设施上的资金在大城市和中小城镇之间的分配比重严重失衡,中小城镇污水的处理率相对较低。这就决定了中小城镇在选择污水处理技术时,首先要考虑的因素必须是经济、高效、节能和简便易行。     

Reaction mechanism of dicofol removal by cellulase

It remains unclear whether dicofol should be defined as a persistent organic pollutant. Its environmental persistence has gained attention. This study focused on its degradation by cellulase. Cellulase was separated using a gel chromatogram, and its degradation activity towards dicofol involved its endoglucanase activity. By analyzing the kinetic parameters of cellulase reacting with mixed substrates, it was shown that cellulase reacted on dicofol and carboxyl methyl cellulose through two different active centers. Thus, the degradation of dicofol was shown to be an oxidative process by cellulase. Next, by comparing the impacts of tert-butyl alcohol (a typical OH free-radical inhibitor) on the removal efficiencies of dicofol under both cellulase and Fenton reagent systems, it was shown that the removal of dicofol was initiated by OH free radicals produced by cellulase. Finally, 4,4′-dichloro-dibenzophenone and chloride were detected using gas chromatography mass spectrometry and ion chromatography analysis, which supported our hypothesis. The reaction mechanism was analyzed and involved an attack by OH free radicals at the orthocarbon of dicofol, resulting in the degradation product 4,4′-dichloro-dibenzophenone.     

宇宙线辐射对人类健康的影响

介绍了宇宙线辐射对人类在不同生活环境和活动空间中所致的剂呈，估计了航空机组人员受到宇线照射潜在的危险性，并作出了卫生学评价。     

The phenology of phytoplankton blooms: Ecosystem indicators from remote sensing

Remote sensing offers many advantages in the development of ecosystem indicators for the pelagic zone of the ocean. Particularly suitable in this context are the indicators arising from time series that can be constructed from remotely sensed data. For example, using ocean-colour radiometry, the phenology of phytoplankton blooms can be assessed. Metrics defined in this way show promise as informative indicators for the entire pelagic ecosystem. A simple phytoplankton–substrate model, with forcing dependent on latitude and day number is used to explore the qualitative features of bloom phenology for comparison with the results observed in a suite of 10-year time series of chlorophyll concentration, as assessed by remote sensing, from the Northwest Atlantic Ocean. The model reveals features of the dynamics that might otherwise have been overlooked in evaluation of the observational data.