北京市大气中CO的浓度变化监测分析

CO是城市大气中一种重要的污染物,在城市和区域的光化学反应中起着重要的作用.用装配氢火焰离子化检测器(FID)的HP5890II气相色谱(GC)方法,以每10min的采样频率,在北京中科院大气物理研究所325m气象环境观测铁塔上(39°9′N,116°4′E),对北京城市大气CO浓度进行了连续监测,时间为2004-01～2004-12.结果显示北京城市大气CO浓度日变化呈双峰型,1d之中出现2个高峰期,早晨07:00～08:00和夜晚22:00～23:00,最高浓度值分别达到13.8mg·m-3,17.1mg·m-3.不同季节CO的日变化存在差异:冬季、秋季的日变化幅度大,而夏季、春季的日变化幅度小.秋季、冬季早晨上班高峰期后CO浓度下降快,春季、夏季上班高峰期后CO浓度下降慢.CO的这种日变化是由地表排放源和气象条件共同决定的.另外,CO存在明显的季节变化,总的表现为浓度最高值出现在冬季12月份(4.0±3.4)mg·m-3,浓度最低值出现在5月份(1.7±0.7)mg·m-3.整个观测期间1a的平均浓度为(2.6±1.9)mg·m-3,采暖期平均浓度为(3.5±2.6)mg·m-3,非采暖期平均浓度为(2.2±1.2)mg·m-3.     

新型阻燃防护服的研发及其性能测试

本文对使用新型纤维材料研发阻燃防护服装的主要工艺,包括各层面料的选择、层次的搭配,参数的确定以及不同层次间的复合进行了分析。同时还对阻燃防护服装应该达到的国家及国际标准、在进行测试时所需要的仪器及测试方法、阻燃防护服装应达到的性能指标进行了详细介绍。     

主扇扩散器出口速度分布的数值模拟与实验研究

借助重整化群双参数湍流模型,建立扩散器内风流流动的控制方程组。基于工程实际,给定模拟边界条件进行数值模拟,并分析扩散器的出口速度分布。根据大量的数值模拟算例,获得节能型扩散器的最优断面扩大系数,找出扩散器出口速度分布与扩散器动能回收之间的关系。通过对节能型扩散器的多工况模型实验,对扩散器出口速度分布进行研讨。借助数值模拟实验与模型验证实验,揭示了扩散器结构形式与扩散器出口动压能损失分布之间的关系。     

Dry deposition and soil-air gas exchange of polychlorinated biphenyls (PCBs) in an industrial area

Ambient air and dry deposition, and soil samples were collected at the Aliaga industrial site in Izmir, Turkey. Atmospheric total (particle + gas) ∑₄₁-PCB concentrations were higher in summer (3370 ± 1617 pg m⁻³, average + SD) than in winter (1164 ± 618 pg m⁻³), probably due to increased volatilization with temperature. Average particulate ∑₄₁-PCBs dry deposition fluxes were 349 ± 183 and 469 ± 328 ng m⁻² day⁻¹ in summer and winter, respectively. Overall average particulate deposition velocity was 5.5 ± 3.5 cm s⁻¹. The spatial distribution of ∑₄₁-PCB soil concentrations (n = 48) showed that the iron-steel plants, ship dismantling facilities, refinery and petrochemicals complex are the major sources in the area. Calculated air-soil exchange fluxes indicated that the contaminated soil is a secondary source to the atmosphere for lighter PCBs and as a sink for heavier ones. Comparable magnitude of gas exchange and dry particle deposition fluxes indicated that both mechanisms are equally important for PCB movement between air and soil in Aliaga.     

Direct observation of microcirculatory parameters in rat brain after local exposure to radio-frequency electromagnetic field

A cranial window method modified for our experiment enabled to observe the cerebral microcirculation including the blood-brain barrier permeability after a local expose to radio-frequency electromagnetic fields with a monopole antenna in rats. The present report reviews our recent publications that reported no noticeable changes in the cerebral microcirculatory parameters due to RF-EMF exposure.     

Exposure assessment of French women and their newborn to brominated flame retardants: determination of tri- to deca- polybromodiphenylethers (PBDE) in maternal adipose tissue, serum, breast milk and cord serum

In the frame of a French monitoring program, tri- to deca- polybromodiphenylethers (PBDE) have been measured in maternal and cord serum, adipose tissue, and breast milk samples, collected from 93 volunteer women during caesarean deliveries. The seven major tri- to heptaBDE (BDE-28, 47, 99, 100, 153, 154, and 183) were detected in adipose tissue and breast milk with cumulated median values of 2.59 and 2.51 ng g⁻¹ l w. Nine highly brominated octa- to decaBDE (BDE-196, 197, 201, 202, 203, 206, 207, 208 and 209) was performed in the same samples, with cumulated median values of 2.73 and 3.39 ng g⁻¹ l w in adipose tissue and breast milk, respectively. At this opposite, median levels of octa- to decaBDE in maternal and cord serum appeared significantly higher than the levels of tri- to heptaBDE in the same matrices, i.e. 8.85 and 12.34 versus 0.98 and 0.69 ng g⁻¹ l w, respectively.     

地质体材料剪切带内部的常剪切应变点及速度分布分析

对于峰后线性应变软化的地质体材料,剪切带内部的总剪切应变等于弹性剪切应变(由经典弹性理论描述)及由微结构效应而引起的局部塑性剪切应变(由非局部理论或梯度塑性理论描述)之和。若剪切应力—塑性剪切应变曲线的斜率的绝对值(称之为软化模量)小于剪切弹性模量的两倍,则在剪切带的任一剖面内存在两个总剪切应变不依赖于剪切应力的点,称之为常剪切应变点。在这两个点上,弹性剪切应变的降低和局部塑性剪切应变的增加处于平衡状态,总剪切速度达到它的最大值或最小值。在两个常剪切应变点之间,局部总速度随剪切应力率的降低而增加。剪切带内部的局部总速度分布是非线性的,这与通常采用的剪切带内部速度的线性分布假定(忽略微结构效应)不同。     

高架连续点源落地浓度预测中风速的确定

高架连续点源污染物排放落地浓度是大气环境影响预测的主要内容。由于大气污染物扩散明显受气象条件尤其是风速的影响,而现有预测模型中对于风速的取值都是按经验值来确定的。通过分析在不同气象和烟源条件下,平均风速的计算方法对烟羽抬升高度以及最大落地浓度产生的影响,与实测值相比较确定了风速取值的合理方法,缩小了预测偏差。     

典型线路板回收过程排放颗粒物的主要成分和特征

分析了南方一典型废旧线路板回收作坊内的空气颗粒物(PM)样品的主要化学组成和特征.结果表明,作坊内的PM水平比较高,平均浓度为(1430±200.8)μg/m3,其组成与其他排放源完全不同.有机物(OM)占PM的46.7%~51.6%,主要的有机成分是有机磷酸酯类,包括磷酸三苯酯(TPP)和其甲基取代化合物、十六酸甲酯、十八酸甲酯、左旋葡聚糖和双酚A.元素碳(EC)对PM的贡献较小.此外,线路板回收过程还排放了大量重金属,尤其是Cd, Pb和Ni.研究结果表明粗放式的线路板回收工艺给当地环境造成了严重危害.     

热喷涂铝涂层与玻璃结合机理的研究

通过改进预处理工艺,解决了采用热喷涂工艺在玻璃上沉积金属的难题,并通过系统的试验,研究玻璃表面预处理工艺、预处理温度及喷涂工艺对涂层结合强度的影响,观察玻璃试样横断面的微观组织,探讨了热喷涂铝涂层与玻璃基材结合机理。