固相萃取-气相色谱法检测水中的邻苯二甲酸酯

利用固相萃取技术富集了水中4种邻苯二甲酸酯类（PAEs）化合物：邻苯二甲酸二甲酯（DMP）、邻苯二甲酸二乙酯（DEP）、邻苯二甲酸二丁酯（DBP）、邻苯二甲酸二（2-乙基己基）酯（DEHP）。借助均匀设计法及计算机回归建模优化技术对4种PAEs的固相萃取条件进行了设计与优化，得到的最佳固相萃取条件：洗脱剂配比（正己烷与丙酮的体积比）30：1，洗脱体积2mL，洗脱速率4mL／min，上样速率8mL／min。富集后的试样用带电子捕获器的毛细管气相色谱仪检测，方法的线性范围为1～1000μg／L（DMP，DEP），0．2—100μg／L（DBP，DEHP），线性回归方程的相关系数为0．9970～1．0000，检出限为0．02-0．4μg／L，4种PAEs的回收率为69％～117％，相对标准偏差为2．5％～9．5％。[关键词]     

湍流模型对预测街道峡谷污染物扩散的影响

文章选取标准k-ε湍流模型、RNGk-ε湍流模型、realizablek-ε湍流模型和单方程Spalart-Allmaras涡黏系数模型对街道峡谷附近的流动和汽车尾气污染物扩散进行了模拟,并与风洞试验值进行了比较,结果表明,4种模型对街谷壁面的浓度预测在趋势上与试验值基本一致,Spalart-Allmaras模型的预测效果最好,realizablek-ε模型预测最差,而标准k-ε模型和RNGk-ε模型的预测介于其间;RNGk-ε模型和realizablek-ε模型的修正作用在预测建筑物尖角和顶部附近的流动处有所体现,但对街谷内浓度分布的预测仍不如标准k-ε模型;本文从流场分布的特点对4种模型的浓度预测差别进行了解释,证明了壁面浓度与其附近的速度和湍流黏性系数的分布相对应。     

水流紊动特性对活性污泥沉降性能的影响

为优化活性污泥处理系统的设计和运行,在SBR反应器中通过改变搅拌浆的转速,调整水流的紊动条件,借助粒子图像测速技术分析了反应器内水流的紊动特性,研究了反应器内不同区域紊动强度对活性污泥沉降性能的影响.结果表明,搅拌浆叶周围15mm的范围内,紊动强度远高于距桨叶更远的区域,距离浆板5mm的1-1断面和距离浆板60mm的3-3断面搅拌轴心处的紊动强度值分别反映了反应器搅拌主体区和其他区的紊动特征.随搅拌浆转速的增加,反应器内各区域的紊动强度逐渐增加,活性污泥的沉降性能表现出先改善后恶化的规律.当反应器搅拌主体区紊动强度1.51%,其他区紊动强度0.31%时,本试验条件下形成的活性污泥沉降指数(SVI)达到最小值67mL/g,界面沉降速率(ZSV)达到最大值0.20mm/s,活性污泥的沉降性能最佳.搅拌主体区范围较小,紊动强度较高,增强该区的紊动强度会加剧污泥的侵蚀破坏;其他区范围较大,紊动强度较低,增强该区的紊动强度对改善污泥的沉降效果作用明显.工程中可通过降低搅拌主体区的紊动强度,选择其他区适当的紊动强度,改善活性污泥的沉降性能.     

催化超临界水氧化技术处理香料废水研究

采用催化超临界水氧化(CSCWO)技术对香料废水进行氧化处理,研究了催化剂浓度、反应温度、压力、停留时间等因素对废水COD、TN去除效果的影响.结果表明:在超临界水中添加cu2+催化剂后有机物的去除效率与无催化剂时相比有显著的提高.香料废水中COD、TN的去除率随催化剂浓度、反应温度和压力的升高,停留时间的延长而提高....     

Isolation and algae-lysing characteristics of the algicidal bacterium B5

Water blooms have become a worldwide environmental problem.Recently,algicidal bacteria have attracted wide attention as possible agents for inhibiting algal water blooms.In this study,one strain of algicidal bacterium B5 was isolated from activated sludge.On the basis of analysis of its physiological characteristics and 16S rDNA gene sequence,it was identified as Bacillusfusiformis.Its algae- lysing characteristics on Microcystis aeruginosa,Chlorella and Scenedesmus were tested.The results showed that:(1)the algicidal bacterium B5 is a Gram-negative bacterium.The 16S rDNA nucleotide sequence homology of strain B5 with 2 strains of B.fusiformis reached 99.86%,so B5 was identified as B.fusiformis;(2)the algal-lysing effects of the algicidal bacterium B5 on M.aeruginosa, Chlorella and Scenedesmus were pronounced.The initial bacterial and algal cell densities strongly influence the removal rates of chlorophyll-α.The greater the initial bacterial cell density,the faster the degradation of chlorophyll-α.The greater the initial algal cell density,the slower the degradation of chlorophyll-α.When the bacterial cell density was 3.6 x l07 cells/ml,nearly 90% of chlorophyll-αwas removed.When the chlorophyll-αconcentration was less than 550μg/L,about 70% was removed;(3)the strain B5 lysed algae by secreting metabolites and these metabolites could bear heat treatment.     

连续水流和间歇水流对微囊藻生长的影响

为了解不同的水体流动方式对铜绿微囊藻生长的影响。实验在控制温度和光照条件下,室内采用野外原水培养基模拟连续水流和间歇水流微囊藻的生长。实验结果表明,间歇水流下微囊藻在各流速下的生长差异较小,连续扰动下微囊藻在各流速下的生长差异较大,在流速为35 cm/s时达到最大值;间歇性扰动条件下微囊藻密度较连续性水流条件下高。这可能是在间歇扰动下水流主要影响藻细胞对营养盐的吸收,连续扰动的低流速下主要是通过对营养盐的吸收对微囊藻产生影响,在高流速下是水流对藻细胞的机械破坏为主;同时培养基中藻细胞形成群体产生微环境有利于微囊藻的生长。水体流动的方式不同,水流对微囊藻细胞生长的作用将发生改变,这为扰动控制蓝藻生长提供科学依据。     

人为扰动下河流复氧激增现象及机制分析

为探究河流复氧规律及其机制,研制出改变河道局部水流流速的深控型水平推流曝气装置,并使用该装置在天津市外环河中进行原位试验,探究人为扰动对河流复氧系数的影响.试验结果表明,装置工作时纵向流速提高至40cm/s,最大增幅22倍;水体溶解氧浓度提高0.6~1.7mg/L,约10%.研究发现,经典的Owens等5组河流复氧系数经验公式均低估了扰动下的复氧系数,试验均值约为49.5d^-1,是理论值的10~100倍,即河流复氧在人为扰动下发生激增现象.分析成因表明,湍流动能与河流复氧系数显著正相关,区别于自然流动,人为扰动提升了水体纵向和垂向湍流动能,加速了中下层水体溶解氧扩散,提高了复氧率,进而发生了复氧激增现象.研究成果为提升城市河流水质的水力学方法提供了科学依据.     

OHP–APT 2002 gravity wave campaign: waves,turbulence and forecasts

In July 2002, a multi-sensor campaign was conducted in southern France to investigate the hypothesized connection between gravity waves and optical turbulence. A generalized scidar (GS) was mounted on the 1.93 m diameter telescope at l’Observatoire de Haute-Provence (OHP). The GS provides continuous profiles of optical turbulence with 300 m vertical resolution from telescope altitude up to 25 km. Thermosondes, which provide in situ measurement of optical turbulence by measuring temperature variance, were launched at the OHP site and at a site approximately 20 km west-northwest of OHP. Gravity wave activity was deduced from temperature and wind velocity measured by radiosondes, which are part of the thermosonde system. In this paper, gravity waves were analyzed using techniques for simple two-dimensional mountain waves, with only fair results. Mesoscale models were run at moderately high resolution for the period. The forecasts were analyzed for wave activity, and a post processor model was used to diagnose the optical turbulence. Mountain waves were evident in the forecast, but quantitative comparison showed the forecast to be inadequate in predicting wave strength. The forecast optical turbulence was in fair agreement with measurements with notable exceptions. This paper is declared a work of the U.S. Government and is not subject to copyright protection in the United States. The U.S. Government’s right to retain a non-exclusive, royalty-free license in and to any copyright is acknowledged. Presented at the Turbulence and Waves in Stably Stratified Atmospheric Shear Flows: Measurements, High Resolution Simulations and Numerical Prediction Challenges Conference, 13–15 September 2004, Lighthill Institute of Mathematical Sciences, University College London, London, UK.     

Mass Transport in Vegetated Shear Flows

Submerged aquatic vegetation has the potential to greatly improve water quality through the removal of nutrients, particulates and trace metals. The efficiency of this removal depends heavily upon the rate of vertical mixing, which dictates the timescale over which these constituents remain in the canopy. Continuous dye injection experiments were conducted in a flume with model vegetation to characterize vertical mass transport in vegetated shear flows. Through the absorbance–concentration relationship of the Beer–Lambert Law, digital imaging was used to provide high-resolution concentration profiles of the dye plumes. Vertical mass transport is dominated by the coherent vortices of the vegetated shear layers. This is highlighted by the strong periodicity of the transport and its simple characterization based on properties of the shear layer. For example, the vertical turbulent diffusivity is directly proportional to the shear and thickness of the layer. The turbulent diffusivity depends upon the size of the plume, such that the rate of plume growth is lower near the source. In the far-field, mass is mixed more than twice as rapidly as momentum. Finally, plume size is dictated predominantly by X, a dimensionless distance that scales upon the number of vortex rotations experienced by the plume.     

A Fine-Scale <Emphasis Type="Italic">k</Emphasis>−ε Model for Atmospheric Flow over Heterogeneous Landscapes

A multi-purpose model for small-scale atmospheric flows over heterogeneous landscapes is being developed. The aim of this research is to build a tool able to predict the dynamical (wind, turbulence) and diffusive (gases, particles) fields over landscapes characterised by heterogeneous plant cover. In its present stage of development the model is based on the numerical integration of neutral atmospheric flow equations, using an energy-dissipation closure scheme and over a domain that may include vegetation layers. Three validation cases of the model are presented: (i) response of the airflow to a change in surface roughness; (ii) airflow within and above a horizontally homogeneous plant canopy; (iii) airflow over two complex forest-to-clearing and clearing-to-forest transitions. All simulations provide results in good agreement with the experimental data, except for turbulent kinetic energy just after a clearing-to-forest transition. This result is not surprising for a statistical k– model in a flow region characterised by strong distorsion and intermittent turbulence. However the overall good performance of the model is promising for environmental research at fine scales over heterogeneous landscapes.