Trees as bioindicator of heavy metal pollution in three European cities

Concentrations of four heavy metals were determined in tree leaves and bark collected from polluted and non-polluted areas of three European cities (Salzburg, Belgrade and Thessaloniki) for a comparative study. Platanus orientalis L. and Pinus nigra Arn., widespread in urban northern and southern Europe, were tested for their suitability for air quality biomonitoring. Leaves and barks were collected uniformly of an initial quantity of about 30 g of each sample. Analysis was accomplished by electrothermal atomic absorption spectrometry after total digestion. Site-dependent variations were found with the highest concentration level measured in Belgrade, followed by Thessaloniki and Salzburg. A higher accumulation of heavy metals was found in bark compared to leaves. Pine tree bark, accumulating higher concentrations of trace metals compared to plane tree bark, shows a higher efficiency as bioindicator for urban pollution. Both indicator species are suitable for comparative studies on bioindication of urban air pollution.     

Comparison of inclined plate sedimentation and dissolved air flotation for the minimisation of subsequent nitrogenous disinfection by-product formation

The formation of disinfection by-products (DBPs), including both nitrogenous disinfection by-products (N-DBPs) and carbonaceous disinfection by-products (C-DBPs), was investigated upon chlorination of water samples following two treatment processes: (i) coagulation-inclined plate sedimentation (IPS)-filtration and (ii) coagulation-dissolved air flotation (DAF)-filtration. The removal of algae, dissolved organic nitrogen (DON), dissolved organic carbon (DOC) and UV₂₅₄ by coagulation-DAF-filtration was superior to coagulation-IPS-filtration. On average, 53%, 53% and 31% of DOC, DON and UV₂₅₄ were removed by coagulation-DAF-filtration process, which were higher than 47%, 31% and 27% of that by coagulation-IPS-filtration process. Additionally, coagulation-IPS-filtration performed less well at removing the low molecular weight organics than coagulation-DAF-filtration process. The concentrations of chloroform, dichloroacetamide (DCAcAm) and dichloroacetonitrile (DCAN) formed during chlorination after coagulation-DAF-filtration reached their maximum values of 13, 1.5 and 4.7 μg L⁻¹, respectively, and were lower than those after coagulation-IPS-filtration with the maximum detected levels of 17, 2.9 and 6.3 μg L⁻¹. However, the trichloronitromethane (TCNM) concentration after the two processes was similar, suggesting that DON may have less of a contribution to TCNM formation than DCAcAm and DCAN.     

室内空气中颗粒物污染特征研究

为获得室内空气颗粒物污染特征,2009年8月18～24日在某单位工作及生活区选取4个室内点和1个室外点进行颗粒物采样和成分分析.结果表明,室内粗颗粒(PM10)符合<室内空气质量标准>(GB/T 18883-2002),而细粒子(PM2.5)的浓度水平较高,表明室内PM2.5的污染较重;室内与室外PM2.5比值显示,P...     

混凝-水解-接触氧化-气浮工艺处理印染废水

采用混凝-水解酸化-接触氧化-气浮工艺,处理印染废水,运行结果表明：对CODcr SS、色度的去除率分别为91．5％、92％、90％,出水达到《纺织染整工业水污染排放标准》（GB4287—92）的一级标准。     

空气过滤技术研究综述

文章分别从空气过滤材料、空气过滤器、空气过滤理论及空气过滤技术的应用等四个方面,对空气过滤技术进行了详细阐述.总结了空气过滤材料、空气过滤器的分类及研究进展、空气过滤器的过滤机理及过滤理论的发展.介绍了空气过滤技术的主要应用,并指出了空气过滤技术的发展动向和市场趋势.     

高砷煤燃烧影响下室内外空气砷含量特征

利用空气总悬浮物采样器和安德森颗粒物分级采样器,对陕西南部燃煤型砷中毒地区的室内外空气样品进行了采集和化学分析,探讨了室内外空气ρ(总砷)与煤w(砷)的关系,以及空气ρ(总砷)在不同粒径颗粒物中的分布特征. 结果表明:室内外空气ρ(总砷)均与煤w(砷)呈显著正相关,烤火间空气ρ(总砷)与煤w(砷)的相关系数(R)为0.80(P<0.01);室外空气ρ(总砷)平均值与当地煤w(砷)平均值的相关系数(R)为0.97(P<0.01);烤火间空气ρ(总砷)高峰主要出现在向煤炉添煤3 h后的旺火期,且旺火期的室内空气ρ(总砷)与空气ρ(粉尘)呈显著正相关(R0.74,P<0.05).与土木结构相比,砖混结构房屋有助于减少燃煤释放到空气中的砷在不同房间之间的扩散;室内不同房间之间、室外不同地点之间以及室内外的空气ρ(总砷)差异主要表现在颗粒物粒径小于2.1 μm的部分;天气状况对室内空气ρ(总砷)随颗粒物粒径的分布没有明显影响.      

以珠三角典型灰霾天气为例谈资料分析方法

分析处理复杂问题需要抓住主流,以珠三角地区发生的一次典型灰霾天气过程为例讨论了抽丝剥茧的资料分析方法.这次灰霾过程同期20日左右,中亚、蒙古国与我国北方发生了当年沙尘天气影响范围最广的一次强沙尘暴过程,冷空气前锋22日凌晨到达穗港地区,但穗港两地空气质量发生了相反的变化,香港空气质量急剧恶化,气溶胶浓度超过700μg/...     

城市空气质量数值预报系统对PM2.5的数值模拟研究

发展了南京大学城市空气质量数值预报模式系统(NJU-CAQPS),在模式系统中引入了气溶胶模块.运用该系统对南京地区冬夏两季PM2.5浓度的时间变化规律和空间分布特征进行了数值模拟研究,通过与实际观测资料对比,检验发展后的模式系统对于细颗粒物的模拟性能.结果表明,南京市城近郊内冬夏两季PM2.5浓度具有明显的时空变化特征,一般在半夜和清晨会出现较高浓度,午后至傍晚浓度较低.冬季浓度高于夏季,冬夏两季算例的浓度日均值之比为1.51.空间分布受到排放源位置、地面流场等因素影响.二次气溶胶在PM2.5中占相当的份额,冬夏两季算例中二次气溶胶在PM2.5中所占比例分别为12%和15%,夏季二次气溶胶对PM2.5浓度贡献较冬季大.与实际观测资料的对比验证表明,经过发展的该模式系统对于城市PM2.5等颗粒物的模拟性能良好.     

催化湿式氧化处理H—酸溶液的反应动力学

两阶段一级反应动力学模型和广义动力学模型被用来描述湿式氧化（ＷＡＯ）及催化湿式氧化（ＣＷＡＯ）反应过程，并确定了动力学参数。２个模型的计算值均与实验值相符，而广义动力学模型相对现准确些。２个确定均表明反尖分２个步骤：首先是Ｈ－酸被迅速氧化成小分子有机酸，后者再缓慢氧化，这２个步骤由模型参数加以表征，因而模型可被用来对ＣＷＡＯ催化剂进行评价。     

空气负离子与温湿度的关系

研究了在自然条件下温度、湿度和温湿度同时改变时空气负离子浓度的变化规律。实验表明,湿度对负离子浓度有明显作用,随湿度逐渐升高(相对湿度10%～80%),负离子浓度从200个 cm3升至8000个 cm3以上,负离子浓度上升的幅度随湿度增加逐渐增大;负离子浓度也随温度升高而升高(在5～40℃之间);温湿度同时变化时,负离子浓度变化率增大。