中国21世纪城市供水新概念--分质供水

结合我国城市一直使用的统一给水方式已与当前水资源紧缺，用水多样化，人们饮用水质质化的状况极不适应的情况，提出对传统的给水方式进行改革的最适宜方式是分质供水。     

Predicting Water Quality Impaired Stream Segments using Landscape-Scale Data and a Regional Geostatistical Model: A Case Study in Maryland

In the United States, probability-based water quality surveys are typically used to meet the requirements of Section 305(b) of the Clean Water Act. The survey design allows an inference to be generated concerning regional stream condition, but it cannot be used to identify water quality impaired stream segments. Therefore, a rapid and cost-efficient method is needed to locate potentially impaired stream segments throughout large areas. We fit a set of geostatistical models to 312 samples of dissolved organic carbon (DOC) collected in 1996 for the Maryland Biological Stream Survey using coarse-scale watershed characteristics. The models were developed using two distance measures, straight-line distance (SLD) and weighted asymmetric hydrologic distance (WAHD). We used the Corrected Spatial Akaike Information Criterion and the mean square prediction error to compare models. The SLD models predicted more variability in DOC than models based on WAHD for every autocovariance model except the spherical model. The SLD model based on the Mariah autocovariance model showed the best fit (r² = 0.72). DOC demonstrated a positive relationship with the watershed attributes percent water, percent wetlands, and mean minimum temperature, but was negatively correlated to percent felsic rock type. We used universal kriging to generate predictions and prediction variances for 3083 stream segments throughout Maryland. The model predicted that 90.2% of stream kilometers had DOC values less than 5 mg/l, 6.7% were between 5 and 8 mg/l, and 3.1% of streams produced values greater than 8 mg/l. The geostatistical model generated more accurate DOC predictions than previous models, but did not fit the data equally well throughout the state. Consequently, it may be necessary to develop more than one geostatistical model to predict stream DOC throughout Maryland. Our methodology is an improvement over previous methods because additional field sampling is not necessary, inferences about regional stream condition can be made, and it can be used to locate potentially impaired stream segments. Further, the model results can be displayed visually, which allows results to be presented to a wide variety of audiences easily.     

非烟气工况下常规烟塔与改造烟塔内部结构的比较

根据流体力学理论,基于Fluent6.3.26计算平台,对常规冷却塔和改造后的排烟冷却塔进行了三维内部流场的模拟。分析非烟气工况下,两塔内部烟道布置对气流的影响,为进一步研究在工况条件下烟气、水蒸气塔内扰流与湿热蒸汽抬升作用提供理论基础。验证了改造烟塔内部烟道布置的优越性,对排烟冷却塔结构优化有一定的指导意义。     

大气环境防护距离确定方法的改进

文章分析了大气环境防护距离的确定现状与存在的问题,针对模式估算可能产生的误差,对现行的大气环境防护距离确定方法提出了改进意见,并阐述了改进方法的可行性。     

城市街谷与上游阻挡建筑最不利间距的研究

采用数值模拟的方法,研究了街谷内上风建筑与上游阻挡建筑的间距（D）,即上游建筑间距,对街谷内空气流动特性和气态污染物分布规律的影响.模拟结果表明,街谷内迎风区的气流速度基本不随D的变化而变化,而背风区和中心区的气流速度随着D的增加呈现先减小后增大的趋势,并在D=90m时,气流速度达到最小值.相应地,在D=90m时街谷内污染物浓度最高,表明D存在最不利值,在城市规划中应尽可能避免该间距.当D大于90m时,D越大,污染物浓度越低,而D小于90m时,D越小,污染物浓度也越低,可以同时实现节约用地和减小交通污染的目的.     

不同情景模式下雄安新区的水资源利用效率和节水潜力分析

雄安新区是千年大计、国家大事,水资源短缺与水体污染成为制约其发展的主要问题。从水资源利用效率及节水潜力视角出发,以深圳发展历程为标杆,结合情景分析与方向性距离函数等模型,展示到2035年不同情景的雄安水资源利用效率及节水潜力发展图景和路径。研究表明：从利用效率看,在基准、起步、建成情景下雄安呈现出由低效率区到较高效率区再到高效率区的变化态势。从节水潜力看,效率改善空间减小、技术落差比增加等表明雄安节水潜力得到充分挖掘。杜绝污水直排、积极发展污水处理技术、优化新区产业结构等是促使水资源利用效率提高的有效手段,是雄安实现绿色生态发展的重要保障。     

中国典型城市PM2.5浓度时空演绎规律及影响因素分析

为探讨空气中ρ（PM_2.5）的空间集聚特征和气候、大气成分变量对空气中ρ（PM_2.5）的影响,利用首批纳入PM_2.5监测的74个城市的ρ（PM_2.5）数据计算Moran's I指数,并选取其中38个典型城市进行计量分析.在基于引力模型的空间权重矩阵基础上,构建面板数据SDM（空间面板杜宾模型）.结果表明:ρ（PM₁₀）、ρ（SO₂）、ρ（CO）、ρ（O₃）、RH（relative humidity,相对湿度）与城市ρ（PM_2.5）呈正相关,而T（temperature,温度）和WS（wind speed,风速）与城市ρ（PM_2.5）呈负相关;ρ（PM₁₀）、ρ（CO）、RH是位于前3位影响城市ρ（PM_2.5）的关键性因素,其总效应分别为0.720 1、0.241 7、0.133 9.地理上邻近城市ρ（PM_2.5）具有明显的外部空间溢出效应,即邻近城市ρ（PM_2.5）每增加10百分点,将导致该地区ρ（PM_2.5）增长6.12百分点.300 km左右是保证PM_2.5区域"联防联控"最佳效果的最大门槛距离,超过该门槛距离,区域"联防联控"的力度和效果会随着距离的增加而逐渐减弱;当门槛距离大于500 km时,ρ（PM_2.5）的空间自相关性不显著.气候变量中,RH和ρ（PM_2.5）呈同方向变化,而T、WS与ρ（PM_2.5）呈反方向变化.研究显示,关注单一地区或单一因素（气候或大气成分）均不能有效控制PM_2.5污染,在保持经济稳定增长的前提下,各地治理PM_2.5应从调整产业结构、优化能源结构、完善防控机制等多个维度共同推进,促使经济增长方式早日从"粗放型"向"集约型"转变.      

不同海拔鬼箭锦鸡儿根际和非根际土壤细菌群落多样性及PICRUSt功能预测

鬼箭锦鸡儿作为我国北方高山和亚高山地区的主要建群植物,是区域生态系统的重要组成部分,但是很少有研究关注其对土壤生态系统的影响及其对环境变化的响应.因而,以鬼箭锦鸡儿为研究对象,采用高通量测序技术,分析了不同海拔鬼箭锦鸡儿根际和非根际土壤细菌群落多样性特征,并进行了功能预测分析.结果表明,所有样品共检测到43门、 112纲、 251目、 324科和542属,变形菌门、酸杆菌门和放线菌门是根际和非根际土壤中的优势菌群.虽然不同海拔之间,鬼箭锦鸡儿根际和非根际土壤细菌多样性指数和群落结构不存在显著差异,但是在同一海拔水平上,根际和非根际土壤细菌多样性指数和群落结构组成存在显著差异.PICRUSt功能预测表明,细菌群落主要涉及氨基酸代谢、碳水化合物代谢、辅助因子和维生素代谢等29个子功能,表现出功能上的丰富性,且代谢为最主要的功能.土壤细菌二级代谢通路预测基因相对丰度的变化与变形菌门、酸杆菌门和绿弯菌门等菌群丰度显著相关,并且土壤细菌预测功能基因组成的差异与土壤细菌群落结构的差异呈显著正相关,说明细菌群落结构与功能基因可能存在密切联系.研究初步探讨了不同海拔梯度下鬼箭锦鸡儿根际和非根际土壤细菌...     

EDTA直接滴定测定镍

参考磷酸在345~356℃时有强腐蚀性的特点,采有硫磷混合酸消解矿样,能使样品消解完全。本方法经加标校核证明,检测结果重现性好,准确度高。     

SOCIAL CLASS DIFFERENCES IN RESERVOIR VISITS1

ABSTRACT: Previous research provides evidence of a socioeconomic bias in outdoor recreational participation. One explanation of this bias is that socioeconomic groups have differential opportunities to participate, with the “costs” of this participation especially serving to restrict the recreational access of lower class persons living in urban areas. Using driving distance as a measure of cost, this study assessed the effects of travel costs on the attendance of three social class groups from an urban population at rural reservoir facilities. Findings support the contention that, while increased driving distance has a dampening effect on recreational participation, this effect is most pronounced for the lower class person. These findings point to the importance of equity considerations in the planning of outdoor recreational facilities.