Biodegradation of polycyclic aromatic hydrocarbons in the natural waters of the Yellow River: effects of high sediment content on biodegradation

The contamination of polycyclic aromatic hydrocarbons (PAHs) has become one of the major problems in the Yellow River of China. As the Yellow River is the most turbid large river in the world, it remains unknown to which extent the high suspended sediment content in the river may affect the fate and effect of PAHs. Here we report the effect of sediment on biodegradation of chrysene, benzo(a)pyrene and benzo(g,h,i)perylene with phenanthrene as a co-metabolism substrate in natural waters from the Yellow River. Biodegradation kinetics of the PAHs in the river water with various levels of sediment contents were studied in the laboratory by fitting with a biodegradation kinetics model for organic compounds not supporting growth. The results indicated that the biodegradation rates of PAHs increased with the sediment content in the water. When the sediment contents were 0, 4 and 10 g/l, the biodegradation rate constants of chrysene with the initial concentration of 3.80 microg/l were 0.053, 0.084 and 0.111 d(-1), respectively. Further studies suggested the enhanced biodegradation rate in the presence of sediment was caused by the following mechanisms: (1) the population of PAH-degrading bacteria in the water system was found to increase with the sediment content; the bacteria population on sediment phase was far greater than that on water phase during the cultivation process; (2) the sorption of PAHs on the sediment phase was well described by the dual adsorption-partition model. Although the sorption capacity of PAH per unit weight of sediment decreased with the increase of the sediment content, the amount of sorbed PAH increased with the sediment content; and, (3) the desorption of PAHs from the solid phase led to a higher concentration near the water-sediment interface. Since the bacteria were also attached to the interface, this resulted in an increased contact chance between the bacteria and PAHs.     

基于POI数据的河道水质空间分布与相关分析

基于苏州古城区河道14个采样点的水质数据和兴趣点(POI)数据,分析古城河水质与周围POI类型之间的相关性.利用主成分分析计算每个采样点的综合水质指标;基于GIS空间分析技术,计算代表人类干扰强度的POI单类型点密度指数和POI多类型核密度指数;最后运用Pearson相关分析探讨POI数据对水质的影响.结果表明,水质高...     

简析公众参与环境影响评价制度

文章主要从公众参与主体范围、公众参与形式、公众参与信息公开、法律保障、公众参与意见等方面指出我国公众参与环境影响评价制度需要完善之处,并针对性地提出:明确公众参与的主体范围、完善公众参与形式、完善环境信息公开制度、建立环境公益诉讼制度、重视公众意见的反馈等完善公众参与的措施。     

Experimental study on an ultra high-rise building evacuation in China

With the development of modern cities, more and more ultra high-rise buildings have been built. Emergency evacuation of such buildings becomes one of the major concerns for building designers, building occupants and governments, especially after the disaster of 9/11. In this study we designed three experiments to investigate the process of ultra high-rise building evacuation. The experiments were performed in Shanghai World Financial Center, which is about 470 m tall. In the first experiment, the evacuation of a single pedestrian from the top floor to the first floor was performed. Movement characteristics such as mean speed and the time needed for evacuation were analyzed. In the second experiment, the mass evacuation process was captured by video cameras and the data were extracted out manually. The evacuees were distributed initially on floors 12–17, and were asked to evacuate through a staircase onto the refuge floor. On the refuge floor, i.e. the 6th floor, the evacuees were required to transit into another staircase to keep moving down to the ground floor. The characteristic space–time curves for each evacuee were extracted and analyzed. Parameters such as the mean speed and the evacuation time, as well as the characteristic of the transit process from one staircase to another were investigated. We at last mimicked and discussed the process of lift evacuation for an ultra high-rise building in the 3rd experiment. Evacuees located on the 41st and 65th floor were asked to move downward by stairs until they came to the refuge floors, where they would evacuate to the ground floor by lifts. The time characteristic of the mixed evacuation strategy was discussed. The basic data obtained from the experiments are useful for building designers and can be used to validate and refine ultra high-rise building evacuation models.     

Stability analysis and comprehensive treatment methods of landslides under complex mining environment—A case study of Dahu landslide from Linbao Henan in China

A case study of Dahu landslide from Linbao Henan in China was discussed in this paper. Based on various kinds of basic data, the 3D numerical model of a geological structure which possesses all kinds of information including the mechanical characteristics and the geometrical parameters of geological discontinuities were known from previous works. Thus, both the whole geological structure and all kinds of geological components involved in a slope can be visualized on computer, the complicated analysis and calculation can be then carried out easily and effectively. Firstly, the combination of 3D numerical model with the limit equilibrium analysis theory in slope stabilization can easily provide the present stability factor. Then according to monitoring data of the total station, the potential sliding trends are analyzed if landslides do not occur. Secondly, there are a number of uncertainties on the factors of multi-forms of disaster, such as, rainfall, earthquake, and mined-out area. The unascertained mathematics theory is applied to the stability comprehensive evaluation. It shows four landslide bodies get to be at unstable state if there are some inducements. Thirdly, sliding distance and movement scope were predicted if landslides occur. On the basis of the analysis above, the treatment of the landslide body called isolated method of culvert was proposed. It has solved the contradiction of landslide and mining radically, and provides important technical assurance for safety and sustainable development of mine.     

宁夏引黄灌区不同土地利用方式土壤微生物群落多样性研究

以宁夏引黄灌区6种典型利用方式(12年果园田、稻旱轮作田、盐化旱田、枸杞田、常年旱田、常年稻田)灌淤土为研究对象,通过同期野外多点采样和室内培养分析相结合,运用磷脂脂肪酸谱图分析方法,探讨了不同土地利用与管理方式下灌淤土理化性质、微生物生物量、微生物区系及微生物群落多样性差异及相关关系,以期为宁夏引黄灌区土壤可持续利用提供数据支撑。结果表明,(1)不同土地利用方式中,长期秸秆还田的盐化旱田、长期有机无机配施的12年果园以及常年旱田3种利用方式下,土壤地力水平较高,相应土壤微生物生物量炭、氮水平最高,有利于土壤微生物数量的保持,而常年淹水条件下的常年稻田土壤肥力水平低下,微生物生物量最低。(2)不同土地利用方式磷脂脂肪酸PLFA总量变幅为81.1-94.8 nmol·g^?1,其中盐化旱田>12年果园>稻旱轮作>常年旱田>枸杞园>常年稻田;好氧细菌14:0、16:0和18:0比例最大,革兰氏阳性细菌16:0iso在12年果园、稻旱轮作田中含量显著提高,放线菌次之,而真菌18:3ω6c在12年果园、盐化旱田、稻旱轮作3种利用方式下含量升高。(3)相关分析表明,引黄灌区土壤磷酸脂肪酸与土壤pH、微生物量碳及微生物量磷之间呈极显著正相关,与土壤有机质呈显著正相关;主成分分析表明,盐化旱田和12年果园具有相近的微生物群落结构。(4)综上所述,有机无机配施常年果园和秸秆还田常年旱田是适用于该地区的土地利用与管理方式。     

高海拔矿井掘进工作面局部增压的空气幕调控仿真研究

矿井环境一直是制约矿井地下安全生产的重要因素之一,尤其是在高海拔地域,由于空气的各项参数都与海拔高度相关,高海拔地区矿井在通风方面要比平原矿井有更多特殊要求。为解决高海拔地区矿井掘进工作面存在的低压缺氧问题,在对高海拔地区低压环境特性分析及传统矿用空气幕理论分析的基础上,根据增能增阻设计提出了多功能矿用空气幕联合增压模型,该模型在巷道两端分别布置引射型和增阻型矿用空气幕,以达到增压进而间接提高工作场所含氧量的效果。以青海省某金矿3 850 m中段开拓巷道掘进作业面为背景,借助有限元仿真软件Fluent对构建的开拓巷道的三维立体模型进行数值模拟。模拟结果与现场实测结果基本相符,结果表明:采用基于空气幕的增压增氧调控技术可使开拓巷道掘进作业面绝对气压由63 835 Pa增加至68 273 Pa,氧分压从12 040 Pa提高至14 213 Pa,达到海拔3 000 m的水平,可明显改善通风效果和通风质量;同时,随掘进作业面压力提高,采空区有害气体的逸出也得到有效抑制。该调控方法可以克服传统风流调控设施存在的布置困难、影响通行的问题,为提高高海拔地区井下压力及含氧量提供了新的思路。     

Citrus essential oils and their influence on the anaerobic digestion process: An overview

Citrus waste accounts for more than half of the whole fruit when processed for juice extraction. Among valorisation possibilities, anaerobic digestion for methane generation appears to be the most technically feasible and environmentally friendly alternative. However, citrus essential oils can inhibit this biological process. In this paper, the characteristics of citrus essential oils, as well as the mechanisms of their antimicrobial effects and potential adaptation mechanisms are reviewed. Previous studies of anaerobic digestion of citrus waste under different conditions are presented; however, some controversy exists regarding the limiting dosage of limonene for a stable process (24–192 mg of citrus essential oil per liter of digester and day). Successful strategies to avoid process inhibition by citrus essential oils are based either on recovery or removal of the limonene, by extraction or fungal pre-treatment respectively.     

换流变压器瓦斯继电器误动作原因分析及改进

针对换流变压器瓦斯继电器存在的误动作问题,在“悬臂梁”结构设计、大电流作用下绕组变形和冷却器同时全启等方面原因进行具体分析,提出了避免瓦斯继电器误动作的有效改进措施。应用结果表明:改进后瓦斯继电器运行环境更为稳定,有效降低了瓦斯继电器误动作的可能性,为后续直流输电工程换流变压器瓦斯继电器设计制造、隐患治理和技术改造等方面提供参考。