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51.
52.
Evaluation of Water Quality in the Chillán River (Central Chile) Using Physicochemical Parameters and a Modified Water Quality Index 总被引:4,自引:0,他引:4
Debels P Figueroa R Urrutia R Barra R Niell X 《Environmental monitoring and assessment》2005,110(1-3):301-322
The Chillán River in Central Chile plays a fundamental role in local society, as a source of irrigation and drinking water,
and as a sink for urban wastewater. In order to characterize the spatial and temporal variability of surface water quality
in the watershed, a Water Quality Index (WQI) was calculated from nine physicochemical parameters, periodically measured at
18 sampling sites (January–November 2000). The results indicated a good water quality in the upper and middle parts of the
watershed. Downstream of the City of Chillán, water quality conditions were critical during the dry season, mainly due to
the effects of the urban wastewater discharge. On the basis of the results from a Principal Component Analysis (PCA), modifications
were introduced into the original WQI to reduce the costs associated with its implementation. WQIDIR2 and WQIDIR, which are both based on a laboratory analysis (Chemical Oxygen Demand) and three (pH, temperature and conductivity), respectively,
four field measurements (pH, temperature, conductivity and Dissolved Oxygen), adequately reproduce the most important spatial
and temporal variations observed with the original index. They are proposed as useful tools for monitoring global water quality
trends in this and other, similar agricultural watersheds in the Chilean Central Valley. Possibilities and limitations for
the application of the used methodology to watersheds in other parts of the world are discussed. 相似文献
53.
54.
Malcolm S. Field 《Environmental monitoring and assessment》1997,47(1):23-37
Ground-water flow and solute-transport simulation modeling are major components of most exposure and risk assessments of contaminated aquifers. Model simulations provide information on the spatial and temporal distributions of contaminants in subsurface media but are difficult to apply to karst aquifers in which conduit flow is important. Ground-water flow and solute transport in karst conduits typically display rapid-flow velocities, turbulent-flow regimes, concentrated pollutant-mass discharge, and exhibit open-channel or closed-conduit flow. Conventional ground-water models, dependent on the applicability of Darcy`s law, are inappropriate when applied to karst aquifers because of the (1) nonapplicability of Darcian-flow parameters, (2) typically nonlaminar flow regime, and (3) inability to locate the karst conduits through which most flow and contaminant transport occurs. Surface-water flow and solute-transport models conditioned on a set of parameters determined empirically from quantitative ground-water tracing studies may be effectively used to render fate-and-transport values of contaminants in karst conduits. Hydraulic-flow and geometric parameters developed in a companion paper were used in the surface-water model, TOXI5, to simulate hypothetical slug and continuous-source releases of ethylbenzene in a karst conduit. TOXI5 simulation results showed considerable improvement for predicted ethylbenzene-transport rates and concentrations over qualitative tracing and analytical ground-water model results. Ethylbenzene concentrations predicted by TOXI5 simulations were evaluated in exposure and risk assessment models. 相似文献
55.
对绵阳市的环境放射源基本情况进行了分析,弄清了放射源的品种、数量。摸索出放射性核素及X射线装置在地域、行业和剂量方面的分布规律,揭示出环境放射性管理工作的重点。 相似文献
56.
环境监测是环境管理的基础性工作,污染源监测报告(数据)的有效性是保证环境执法严肃、公正的重要条件,也是是守法企业展示良好社会形象的基本保证。依照国家的相关规定,并结合行业技术规范的要求,探讨污染源监测报告的有效期问题,以利于相关各方严肃、科学、合理地使用污染源监测数据。 相似文献
57.
CCl4体外引发自由基反应的简易实验方法 总被引:1,自引:0,他引:1
通过对不同剂量CCl4与小鼠肝匀浆温育反应液中丙二醛(MDA)含量的测定,确立了CCl4体外引发自由基反应的简易实验方法,并对实验方法进行了考核评定.同时以Hg2 对CCl4体外引发小鼠肝匀浆自由基反应的影响为应用实例进行了研究,结果表明,Hg2 与CCl4的毒性有协同作用. 相似文献
58.
为了研究来自不同方向的沙尘暴对和田绿洲大气环境质量的影响,本文利用HYSPLIT后向轨迹模型和NCEP的GDAS全球气象要素数据,将和田绿洲西北部的墨玉县城作为模拟受点(37.26°N,79.72°E),计算2016年1月1日—2018年12月31日发生的每一次沙尘天气期间逐日18:00(世界时)36 h后向气流轨迹,轨迹计算起始高度设置为500 m,并结合相应的PM2.5、PM10、SO2、NO2、CO、O3浓度监测数据进行聚类分析,研究抵达该地区的沙尘暴的主要移动轨迹和污染物输送路径.同时,运用潜在源贡献因子分析法(PSCF)和权重污染轨迹分析法,分析了沙尘暴期间不同气流轨迹对墨玉县污染物浓度的影响,识别大气污染物的潜在源区,揭示不同源区对污染物浓度的贡献差异.结果表明,影响和田绿洲(墨玉县)的沙尘暴主要来自西北(WN)、北(N)、东北(EN)和东(E)4个方向;其中,来自东部的沙尘天气频率最高(60.2%),但主要以浮尘天气为主;扬沙和强沙尘暴主要来自西部方向,54.48%的强沙尘暴和38.53%的扬沙来自西和西北方向.不同沙尘源区和不同传输路径上的沙尘气溶胶对和田绿洲大气环境的影响不一样.沙尘天气期间,大气PM2.5和PM10的平均浓度相当于无沙尘天气期间的3~5倍,但对SO2、NO2、CO、O3质量浓度的影响不大;由西向东和由北向南的沙尘暴对墨玉县PM2.5和PM10质量浓度的贡献率最大;由东向西的沙尘暴由于路过和田市和洛浦县等工业污染源区,此簇沙尘暴气团将该区域SO2、NO2、CO等污染颗粒携带到墨玉县,因此,东-东南(E-ES)方向的沙尘暴对SO2、NO2、CO的贡献率分别为15.56%、20.55%和21.57%.本文定量印证了沙尘暴对和田绿洲大气环境质量的影响,可为绿洲区沙尘暴研究提供参考. 相似文献
59.
60.
A new procedure of determining optimal C/N (the rate of carbon source to nitrogen source) of mixed distillers' grains for combined bacteria synergic fermentation is established. At the same time an improved method evaluating bacteria growth, called method of dry cell weighing by filtering is developed. For each combination of C and N , their initial and residual contents before and after fermentation respectively are determined. Then followed the calculation of utilization of C and N sources by the compound bacteria. The optimal C/N is finally located from among the utilization of C and N of several combinations and the weight of produced mass of oven-dried thallus The conditions of fermentation are: inoculum size 10%, temperature 30.0℃, rotational speed 170 r/min, shake culture time 48h. The best results obtained from orthogonal experiments are: maximum mass of oven dried thallus is 14.693g in a liter liquid medium, maximum utilization rate of carbon source is 98.13% and maximum utilization rate of nitrogen is 78.14%. Optimal C/N is 5.1. 相似文献