砂尘环境试验风洞稳定段和收缩段的数值模拟研究

采用计算流体动力学软件FLUENT,对砂尘环境试验风洞中稳定段和收缩段的气固两相流流场进行数值模拟.给出了计算采用的湍流模型及计算区域的网格划分技术.通过分析稳定段和收缩段的两相流流场的速度梯度分布,得到了反向加砂方式优于正向加砂方式的计算结果.     

基于GIS的南充市水资源综合管理系统设计

为了实现南充市水资源的高效利用,建设一个适用于现代信息网络化的水资源实时监控系统十分迫切,具有重要的现实意义和巨大的经济价值。本文对该系统设计体系结构、空间数据、各个系统功能作了说明。     

绵竹市地表水环境质量现状及水环境容量分析

本文通过对绵竹市污染源现状调查及地表水环境现状评价,计算并分析了境内主要河流的水环境容量。绵竹市地表水环境污染较为严重,水环境容量短缺已成为绵竹市主要环境制约因素。为实现绵竹市水环境保护与经济社会的可持续发展,需及时采取污染物总量控制、工业污染防治、生活污水处理、控制农村面源污染等一系列措施。     

成雅高速公路两侧大气颗粒物中重金属分布规律研究

本文以成雅高速公路为研究对象,采集公路两侧大气颗粒物样品,通过微波消解——火焰原子吸收法测定大气颗粒物中铅、镉、铜、锌的含量。研究表明,成雅公路两侧距路肩200m范围内大气颗粒物已受不同程度的铅、镉、铜、锌污染,其中重金属含量Pb〉Zn〉Cu〉Cd,并获得成雅高速公路两侧大气颗粒物中重金属污染的分布规律。     

北京旅游景区游客满意度及其影响因素分析

基于对北京3个重点景区游客的随机问卷调查,借鉴国内外已有的顾客满意度评价模型,构建了城市游客满意度测评模型,并利用SPSS11.5和AMOS5统计软件对北京旅游景点游客满意度进行了测算与评价。结果表明,北京游客综合满意度为69.23,水平还较低;游客的忠诚度较高,游客抱怨度较低;游客满意度主要受感知质量和景区形象影响,较低的感知质量直接导致了较低水平的游客满意度;游览安排和景区特色对感知质量有显著影响。今后,北京应加强景区特色的构建和游客投诉管理,规划更为合理的游览安排,提高社会服务水平,为游客提供“零缺陷”的旅游产品。     

生态养生旅游产品开发初探

生态养生旅游是一种以生态环境为背景、休闲养生活动为主题的专项旅游产品。中国城市化的发展、人口老龄化的加剧,使国人对康体保健旅游产品需求和生态养生旅游市场需求越来越旺盛,开发前景极为广阔,但目前学术界在这方面的研究还不多。在分析生态养生旅游产品市场的基础上,探究其开发的原则和方法。     

Integrated Modular Modeling of Water and Nutrients From Point and Nonpoint Sources in the Patuxent River Watershed1

Abstract: We present a simple modular landscape simulation model that is based on a watershed modeling framework in which different sets of processes occurring in a watershed can be simulated separately with different models. The model consists of three loosely coupled submodels: a rainfall‐runoff model (TOPMODEL) for runoff generation in a subwatershed, a nutrient model for estimation of nutrients from nonpoint sources in a subwatershed, and a stream network model for integration of point and nonpoint sources in the routing process. The model performance was evaluated using monitoring data in the watershed of the Patuxent River, a tributary to the Chesapeake Bay in Maryland, from July 1997 through August 1999. Despite its simplicity, the landscape model predictions of streamflow, and sediment and nutrient loads were as good as or better than those of the Hydrological Simulation Program‐Fortran model, one of the most widely used comprehensive watershed models. The landscape model was applied to predict discharges of water, sediment, silicate, organic carbon, nitrate, ammonium, organic nitrogen, total nitrogen, organic phosphorus, phosphate, and total phosphorus from the Patuxent watershed to its estuary. The predicted annual water discharge to the estuary was very close to the measured annual total in terms of percent errors for both years of the study period (≤2%). The model predictions for loads of nutrients were also good (20‐30%) or very good (<20%) with exceptions of sediment (40%), phosphate (36%), and organic carbon (53%) for Year 1.     

Anaerobic degradation behavior of nonylphenol polyethoxylates in sludge

Anaerobic biodegradation behavior of nonylphenol polyethoxylates (NPEOs) was investigated. Results showed that terminal electron acceptors, organic matters, initial concentration, and temperature had great influence on the anaerobic biodegradation of NPEOs. Anaerobic biodegradation of NPEOs could be enhanced by adding sulfate or nitrate while this process could be inhibited by adding organic matters. The maximum removal rate increased 1.24 microM d(-1) for each ten micromoles increase in initial concentration. The decrease in temperature caused a sharp decrease in the removal efficiency of NPEOs. The temperature coefficient (PHI) for the anaerobic biodegradation of NPEOs was 0.01 degrees C(-1). Nonylphenol (NP), the typical intermediate of NPEOs, could inhibit the anaerobic biodegradation of NPEOs only at high concentration. However, these environmental factors had no effect on the anaerobic biodegradation pathway of NPEOs. The accumulation of NP and short-chain NPEOs during NPEO biodegradation led to a significant increase in the estrogenic activity during the biodegradation period.     

Influence of clay minerals on the reduction of Cr6+ by citric acid

The influence of clay minerals on the reduction of Cr6+ by citric acid was investigated at pH values 4.0, 4.5 and 5.0 at 25 degrees C. The results indicate that montmorillonite and illite greatly accelerate the reduction reactions at pH 4.0 and 4.5, but their effects are dramatically reduced at pH 5.0. The role of clay minerals in accelerating the reactions is in the order: illite>montmorillonite>kaolinite, which has a positive correlation with the amount of Mn2+ adsorbed on the surfaces of these minerals. With light, Fe(3+) also significantly increases reaction rates. Ethylenediaminetetraacetic acid (EDTA) greatly suppresses the acceleration of the reduction reactions by these minerals, indicating that EDTA competes with citric acid for Mn2+. Thus, the formation of complexes between Mn(2+) and citric acid could be a prerequisite for the acceleration of the reductions of Cr6+ by clay minerals. In addition, there is no relationship between the specific surface area of clay minerals and the reduction rate of Cr6+ by citric acid.     

Evaluation of an electrolysis apparatus for inactivating antineoplastics in clinical wastewater

We recently reported a system for inactivating antineoplastics in which sodium hypochlorite is supplied by the electrolysis of sodium chloride solution. In this study, we designed an electrolysis apparatus for inactivating the cytotoxicity of antineoplastics in clinical wastewater using the system. The apparatus consists of an electrolysis cell with platinum-iridium electrodes, a pool tank, a circulating system for wastewater, a safety system for explosive gas and overflow, and an exhaust duct. The free chlorine concentration increased linearly up to 6500 mg l(-1), and pH also increased to 9.0-10.0 within 2h, when 0.9% sodium chloride solution was electrolyzed. We examined its efficacy with model and clinical wastewaters. The reciprocal of dilution factor for disappearance of cytotoxicity using Molt-4 cells was compared before and after electrolysis. In the model wastewater, that was 9.10 x 10(4) before electrolysis, and 3.56 x 10(2) after 2h of electrolysis. In the clinical wastewater (n=26), that was 6.90 x 10(3)-1.02 x 10(6) before electrolysis, and 1.08 x 10(2)-1.45 x 10(4) after 2h of electrolysis. Poisonous and explosive gases released by the electrolysis were measured; however, they were found to be negligible in terms of safety. The environmental load was evaluated by carbon dioxide generation as an index and it was found that the carbon dioxide generated by the electrolysis method was 1/70 lower than that by the dilution method with tap water. Moreover, the cost of the electrolysis method was 1/170 lower than that of the dilution method. This method was found to be both effective and economically valuable.