特长公路隧道内的横通道间距和车行间距研究

隧道火灾,尤其是长大公路、铁路隧道火灾,往往是灾难性的。因此,基于性能化防火设计原理,对雪峰山特长公路隧道的横通道间距和车行间距进行了研究。对中等规模20 MW的火灾,按照规范建议的3 m/s的风速进行通风的情况下,先用CFD软件模拟计算火灾危险时间Tfire,然后由疏散模型中的经验公式计算人员疏散时间Tevac,比较分析不同横通道间距下人员疏散的安全性;同时为了避免隧道内车辆间的引燃,利用辐射换热原理,对车辆间的火灾蔓延性进行了分析。模拟结果为:最佳横通道间距约为290 m,最小引燃间距为6 m。考虑到建设成本的问题,建议雪峰山隧道的横通道间距改为300 m;同时,考虑到后继车辆的刹车及不同的行车速度等因素,建议特长隧道内车距最好要大于110 m;     

战略环境评价(SEA)及其研究进展

战略环境评价(SEA)是目前环境评价领域中令人关注的前沿课题 .本文对 SEA的提出和发展进行了回顾 ,对国外开展SEA的实践进行了归纳分析 ,探讨了 SEA的作用、区域特征、评价因素、基本程序、技术方法和机制 ,论述了 SEA与项目 EIA的关系 ,并介绍了香港和内地 SEA的初步实践 .     

加强高校大学生文化素质教育势在必行

本文针对国高校大学生素质不全面的问题,指出了我国目前教育方式的两种弊端和教育理念上的两个误区,提出了加强高校大学行文化素质教育的对策。     

ECD氧气诱导法分析大气中痕量HCFC-22

HCFC-22(CHClF₂)是CFC-12的主要替代物,它在大气中的体积分数仅为10^-12级.而且对ECD检测器响应灵敏度很低.本文经过低温浓缩进样后采用氧气诱导法来增强ECD对它的分析灵敏度,载气中氧气的体积分数为0.54%时,信噪比最大,此时ECD灵敏度增强约500倍.结合该条件下ECD温度选择、程序升温和载气流量的研究,建立了高灵敏度ECD气相色谱测定大气中HCFC-22浓度的实用分析方法.     

Eutrophication status and control strategy of Taihu Lake

The water quality and eutrophication status of Taihu Lake in recent years are presented and the pollution trends are analyzed. It is shown that because of unreasonable industrial structures, pollution discharge per GDP is high within the Taihu basin, and the pollution discharge from point and non-point sources exceed the basin’s environmental carrying capacity. Especially, excessive pollutants containing nitrogen and phosphorus are being discharged. Moreover, eutrophication may also result from internal pollution sources such as the release of nutrient elements from sediment. All these factors have resulted in the water quality deterioration of Taihu Lake. To solve this environmental problem, possible control strategies are summarized, including the control of internal pollution sources and inflow-river pollution, ecological restoration and reconstruction of the degraded lakeside zone ecosystem, clean water diversion, dredging, and manual algae removal.     

噪声合格审定在降低飞机噪声污染中的应用

噪声污染是航空环境工程领域的重要问题,噪声合格审定已成为降低飞机噪声污染的一种重要途径。为了完善我国的飞机噪声合格审定技术规范,对飞机噪声有效感觉噪声级的计算方法进行了研究;在飞机噪声合格审定过程中,实际飞行实验条件与噪声合格审定规范中规定的基准条件存在差异,依据飞行实验中相应的几何条件和噪声传播的规律,建立了使用积分修正方法计算有效感觉噪声级的完整方法;以CRJ700飞机为例说明了该方法在噪声合格审定中的应用,并且以Boeing747系列飞机为例阐明了噪声合格审定在降低飞机噪声污染的重要作用。     

BDD电极阳极氧化垃圾渗滤液纳滤浓缩液

实验研究了电化学技术阳极氧化垃圾渗滤液纳滤浓缩液,比较了不同阳极种类、电流密度和极板间距对污染物降解的影响。结果表明,掺硼金刚石(boron-doped diamond,BDD)薄膜电极作为阳极,比钛基镀钌铱(Ti-RuO2-IrO2)和钛基镀铂(Ti-Pt)电极作为阳极时,有机物的矿化更为迅速。选用BDD电极作为阳极,不锈钢电极作为阴极,随着电流密度的增加(10~100 mA/cm2),TOC去除率随之提高,极板间距的改变(2~12 mm)对TOC的降解影响较小。BDD阳极氧化6 h后,浓缩液的TOC去除率达到94%。研究表明,BDD电极阳极氧化技术可有效地处理垃圾渗滤液纳滤浓缩液,可将其应用于高毒性难生物降解的有机废水的处理工艺中。     

基于零排放浓盐水处理技术的发展

对基于零排放浓盐水处理技术存在的问题进行了简单分析,然后对基于零排放浓盐水处理技术不同工段的处理新技术进行了简单介绍,最后分析了今后基于零排放浓盐水处理技术的发展方向。     

造纸工业水污染现状与治理措施

造纸行业企业数量多、规模差异大、能耗高、水污染物排放量大,应控制造纸工业的水污染,改善环境,进一步减轻造纸行业废水排放对水体的污染.本文分析了制浆、抄纸等工艺产生的污染物,针对具体工艺提出治理方法与措施.     

Effects of fenvalerate concentrations and its chiral isomers on bacterial community structure in the sediment environment of aquaculture ponds

To investigate the effect of chiral pesticide fenvalerate (FV) on the micro-ecological environment of aquaculture pond sediment, we used an indoor static experiment to observe the effects of FV added at different concentrations with different chiral isomers on the changes in the sediment bacterial community. The 16S rDNA high-throughput sequencing technique was used to conduct sequencing and analysis of the bacterial community structure as well as changes in aquaculture pond sediments after 4 weeks of cultivation. The results showed that the microbial alpha diversity indices (Sobs and Shannon indices) of the treated groups were significantly lower than those of the control group after 4 weeks (P < 0.05), and the values in the high-concentration group were significantly lower than those of the low-concentration group (P < 0.05). In terms of bacterial group composition, the proportion of abundance of Proteobacteria and Acidobacteria in the treated groups were greater than in the control group after 4 weeks, while the proportion of abundance of Bacteroidetes and Verrucomicrobia were lower. In the high-concentration FV treatment group, the proportion of abundance of Bacteroidetes, Acidobacteria, Chloroflexi, Nitrospinae, unclassified_k_norank, Ignavibacteriae, and Nitrospirae were significantly different from those of the other groups (P < 0.05). Principal coordinate analysis (PCoA) and ANONISIM/Adonis analysis showed that the cis-enantiomer had a stronger effect on the bacterial community as the concentration of FV increased. In addition, the linear discriminant analysis effect size (LEfSe) and linear discriminant analysis (LDA) results revealed differences in the level of enrichment of bacterial groups caused by FV at different concentrations and isomer levels. Collectively, this study showed that FV residue has a pronounced effect on bacterial communities in sediment, which becomes more significant with increasing exposure concentration. The effects of the cis- and trans-enantiomers of FV on the sediment environment are different; the cis-enantiomer has a stronger effect on the bacterial community.