雾天气下二次气溶胶均质成核生长过程

二次气溶胶的核化过程涉及分子杂乱运动和碰撞,在分子间的范德华力作用下,大气环境系统中产生分子聚合,形成分子团、胚胎和核.基于此建立二次气溶胶核化和生长模型,并且采用颗粒群平衡模拟和多重蒙特卡洛方法,对雾天气下水汽均质同分子核化及H₂O-H₂SO₄均质异分子核化的过程开展热力学和动力学数值研究. 结果表明:在水汽均质核化过程中,当水汽过饱和比从2增至10时,水汽的成核速率增加约73个数量级,形成临界胚胎所需的分子数降低了97.3%. 而对于H₂O-H₂SO₄均质异分子核化过程,在环境温度271.15 K,气态H₂SO₄分子数浓度为5×107cm-3条件下,当RH(相对湿度)由80%增至100%时,二次气溶胶成核速率增加1.4倍;在气态H₂SO₄分子数浓度较高、RH较大时,核化形成的临界胚胎粒径较小. 经过均质核化生长后,二次气溶胶粒径处于1.5～3.5 nm.      

基于云模型的电梯运行可靠性模糊综合评估

针对目前电梯可靠性评估中存在随机性和模糊性等不确定性的问题,提出了一种基于熵权法、云模型和模糊综合评价法的电梯运行可靠性评估模型。通过分析电梯各个子系统的主要特征量,建立了电梯运行可靠性评估指标体系,并运用熵权法确定各指标的权重。根据云模型实现定量指标与定性概念之间的转换,得到定量评估指标的等级隶属度。最后基于模糊综合评价法,对各指标信息进行自上而下地综合,得到整体的可靠性评估结果。实例表明了该模型的正确性与有效性,能够对电梯的状态检修提供参考。     

新疆干旱区气溶胶间接效应区域性分析

利用MODIS气溶胶和云资料以及实测的降水数据,可从宏观角度分析新疆区域气溶胶时空分布特征,研究气溶胶与云和降水之间的相互影响关系.结果表明：近十年来受区域暖-干趋势的转变影响,新疆地区气溶胶光学厚度空间分布呈现显著的区域性和季节性差异;南疆地区气溶胶光学厚度整体高于北疆地区,春、夏高,秋、冬低,整体呈现增加趋势,其中,北疆地区气溶胶光学厚度变化程度相对较为显著;受气候变化和颗粒粒径差异影响,新疆干旱区云光学厚度与气溶胶光学厚度呈负相关变化趋势,相关系数北疆地区高于南疆地区;云水路径受温度、湿度影响较大,对气溶胶光学厚度的变化的敏感程度北疆大于南疆,夏季最高,冬季最低;气溶胶光学厚度与云滴粒子有效半径关系复杂,受水汽影响较大,在云层含水量较低的情况下,云滴粒子有效半径与气溶胶光学厚度呈负相关,说明在干燥地区或季节,气溶胶的增加,抑制云滴粒子的增长;整体来看,新疆干旱区气溶胶的增加抑制了区域降水的形成.     

基于云模型的运营隧道结构健康安全评价

为了实现运营隧道结构健康安全评价,选取19个指标因素作为评价指标,并基于大量工程实践和专家经验,进行云模型连续型影响因素属性离散化,得到运营隧道风险评价因子云模型分级标准。根据风险因子的不确定性,建立运营隧道结构健康安全评价云模型,并通过实例进行验证。结果表明,基于云模型的运营隧道结构健康安全等级具有较好可行性与适用性。同时,通过敏感性分析得到影响运营隧道结构健康安全的敏感性因素,为运营隧道结构健康安全控制提供支持。     

Chemometrical analysis and quality control of pot water and its sources from Athens,Greece

The present study describes a chemometrical interpretation of a large data set from pot water quality control results. Sixteen chemical and physicochemical parameters constantly checked throughout the year were involved in the classification procedure. The data originate from seventeen sampling stations (pot water sources and pot water purification stations) and were collected in the period January ‐December 1993. Mean values for two months periods were introduced to the chemometrical procedure, so finally a data set 101x16 was formed. Additionally, quality control requirements of the European Union for pot water were added to the set to form an information input matrix of 103x16 elements. Hierarchical and non‐hierarchical clustering procedures were applied in order to reveal the internal structure of the data set. Some interesting conclusions like special water quality of lake Mornos, possibility of quality monitoring with lesser number of components etc., concerning the quality and stability of the pot water sources and quality characteristics of the samples are made.     

Trace metals used as natural markers for discriminating some karstic freshwaters near Trieste (Italy)

Some heavy metals have been determined using voltammetry in freshwaters forming part of a karstic hydrological system (the Timavo River, north of Trieste), during attempts to characterize and discriminate the different sources of the springs. The trace elements can be considered natural markers, with lead appearing to be the most discriminating variable. Non parametric statistics and cluster analysis were used to estimate the significance of the determined parameters with respect to the considered ecosystem.     

运用相对组成探针技术研究青藏高原POPs大气传输与来源

为探讨青藏高原大气POPs(持久性有机污染物)空间分布趋势、来源和传输特征,应用POPs相对组成探针技术对16个大气被动采样观测点的数据进行分析,将青藏高原空间尺度上的采样点聚为不同的组,以探讨污染物来源及大气传输过程. 结果表明:青藏高原大气中的HCB(六氯苯)主要来自于本地燃烧,其中人类活动较为频繁的城镇(波密、格尔木、玉树、拉萨、工布江达、拉孜、那曲)具有较高的HCB相对组成(25%～74%). 青藏高原南缘(包括珠峰、然乌、萨嘎)以南亚正在使用的农药——HCHs(六六六)和α-Endo(硫丹)为特征(二者的相对组成之和超过了40%),凸显了南亚污染排放经长距离传输对青藏高原的影响. 剔除HCB影响后,青藏高原中部、东南部河谷地区(鲁朗、拉孜、拉萨、日喀则、工布江达、昌都)及那曲、狮泉河因具有较高的o,p'-DDT相对组成而聚为一组,平均值为40%,表明这些采样点可能受到本地污染排放的影响.      

东北典型湖库水体对铜绿微囊藻荧光特性的影响

为考察东北典型湖库水体对铜绿微囊藻(Microcystic aeruginosa)生长过程中IDOM(细胞内溶解性有机物)荧光特性的影响,在镜泊湖、兴凯湖、五大连池、松花湖和大伙房水库5个典型湖库,共10个采样点采集水样,用于铜绿微囊藻的培养,利用EEM(三维荧光光谱)技术,结合三维荧光FRI(区域体积积分)开展IDOM荧光特性的聚类分析. 结果表明:铜绿微囊藻中IDOM的主要荧光特征峰为类蛋白荧光峰(峰S和峰T),峰S荧光强度高于峰T;对IDOM的三维荧光光谱分为5个区(Ⅰ～Ⅴ区)进行区域体积积分,荧光响应值比例(P_Ⅰ+Ⅱ,n和P_Ⅳ,n)总体上呈互补趋势;Ф_T,n(总区域体积积分)表现为镜泊湖>五大连池>兴凯湖>松花湖>大伙房水库,第16天镜泊湖的Ф_T,n最大,平均值为9.76×10-5 AU·nm2/(mg/L);大伙房水库的Ф_T,n最小,平均值为3.72×10-5 AU·nm2/(mg/L). 聚类分析将10个采样点分成3类. HJ1、HJ2采样点为类别1;HX1、LD1、JS1、LD2采样点为类别2;HX2、JS2、HW2、HW1采样点为类别3,其中,类别1(镜泊湖)水体较类别2和类别3水体更适宜铜绿微囊藻的生长.      

基于探地雷达快速测定土壤含水量试验研究

试验点选择在古尔班通古特沙漠南缘中国科学院阜康荒漠生态系统研究站,以探地雷达为主要数据采集工具。结合探地雷达两种测量方式特点,提出了探地雷达最佳天线间距判定方法,达到快速测定中尺度土壤水分含量的目的。研究结果表明:固定天线间距测量下,得到最佳天线间距为1.9 m,提取了该天线间距下的地面波,进行了土壤含水量计算,测线上30.5 m点测定的土壤含水量与标后的时域反射仪法结果对比,在该试验点探地雷达地面波法测定上层土壤含水量的有效深度为20 cm,其偏差仅为0.015 m³/m³,精度能够满足实际需求,测线0~36.5 m间沙地上层土壤含水量表现出空间异质性,该方法能快速精确测定中尺度土壤含水量,为农业生产和作物灌溉提供科学依据。     

Evaluation of the performance of rural wastewater treatment plants using chemical measurements in combination with statistical techniques: a case study

The performance of a wastewater treatment plant was assessed statistically using multivariate cluster and principle component analysis. This was after measuring some physico-chemical properties in the influent, effluent, downstream, and upstream waters over a 4-month period. The cluster analysis grouped the sampling sites into three clusters: relatively non-polluted (upstream), medium polluted (downstream), and polluted (influent and effluent). The polluted water was further subdivided into very highly (influent) and highly (effluent) polluted. The grouping of influent and effluent into one cluster was due to some water quality parameters such as amount of copper, lead, and phosphates that are not efficiently removed by the plant. Using principal component analysis, samples from the same site taken over a period of 4 months were scattered, indicating inconsistencies in the performance of the plant. This was more pronounced during the rainy season, suggesting that increased water volumes from open sewers make the already poorly performing plant worse. The major loading factors found by principle component analysis were phosphate, lead, iron, zinc, copper, pH, and conductivity. Generally, the wastewater treatment system was found to be efficient in removing heavy metals and these were found in the sludge, but not anions. The mean percentage metal removal could be arranged in the following decreasing order: iron (85%)?>?zinc (57%)?>?copper (40%) and lead (38%) following the concentrations (mg?kg^?1) found in the sludge: iron (11,300)?>?zinc (820)?>?copper (180)?>?lead (20)?>?cadmium (3). Phosphate and iron concentrations in the effluent were found to be above the South African Bureau of Standards (SABS) recommendations. The major cause of poor performance is the high volume of the wastewater, exceeding the capacity of the plant 10 times.