间接竞争ELISA方法测定水中2，4-D的研究

以2,4-D-BSA为包被抗原,采用自行制备的2,4-D单克隆特异性抗体6D11建立了水中2,4-D的间接竞争 ELISA检测方法．本研究比较了包被抗原2,4-D-BSA浓度分别为240ng·mL-1、120ng·mL-1和60ng·mL-1的反应体系和竞争反应时间为60min和15min的间接竞争ELISA剂量-反应曲线,确定了当包被抗原浓度为60 ng·mL-1、竞争反应时间为15min时,剂量-反应曲线的IC50值较低．采用上述实验条件分别测定了由PBS缓冲溶液、饮用水、清华大学地下水和圆明园福海地表水配制的2,4-D标准溶液的剂量．反应曲线,发现实际水样的基质效应对检测结果的影响较大;采用实际水样和PBS缓冲溶液配水在含有5％乙醇的PBS缓冲体系中反应的方法,基本上消除了基质效应对检测结果的干扰．采用上述优化试验条件,测定2,4-D浓度分别为0．5mg·L-1、0．125mg·L-1和0．03mg·L-1的加标样品,测定数据的准确度符合痕量有机污染物定量检测对准确度的要求,但是平行样品测定数据之间的变异系数较大,需要进一步改进检测方法,用于实际水样的检测．     

NON-ZERO LOWER LIMIT IN LOW FLOW FREQUENCY ANALYSIS?1

ABSTRACT: The implications of fitting distributions with non-zero lower limits to low flow data are examined. The 3-parameter Weibull distribution is fitted to annual minimum flow series from 60 long term stations in Canada. The relations between the estimated lower limit and three sampling variables (skewness, smallest, and largest observations) were investigated. The lower limit strongly depends on the sample skewness; it varies directly with the sample skewness, which in turn is highly influenced by the largest observation. For a given skewness, the value of the estimated lower limit is determined by the value of the smallest observation. Therefore, the lower limit cannot be accurately determined, and the resulting low flow estimates will be either too small or too high.     

人发中微量钴的分光光度测定

本文应用显色剂5-(2＇-噻唑偶氮)-2,4-二氨基甲苯(简称2,4-TADAT)测定了人发中的钴,方法操作方便、选择性好,获得满意结果.     

A terrain-based paired-site sampling design to assess biodiversity losses from eastern hemlock decline

Biodiversity surveys are often hampered by the inability tocontrol extraneous sources of variability introduced intocomparisons of populations across a heterogenous landscape. If not specifically accounted for a priori, this noisecan weaken comparisons between sites, and can make itdifficult to draw inferences about specific ecologicalprocesses. We developed a terrain-based, paired-sitesampling design to analyze differences in aquaticbiodiversity between streams draining eastern hemlock (Tsuga canadensis) forests, and those draining mixedhardwood forests in Delaware Water Gap National RecreationArea (USA). The goal of this design was to minimize variancedue to terrain influences on stream communities, whilerepresenting the range of hemlock dominated streamenvironments present in the park. We used geographicinformation systems (GIS) and cluster analysis to define andpartition hemlock dominated streams into terrain types basedon topographic variables and stream order. We computedsimilarity of forest stands within terrain types and usedthis information to pair hemlock-dominated streams withhardwood counterparts prior to sampling. We evaluated theeffectiveness of the design through power analysis and foundthat power to detect differences in aquatic invertebratetaxa richness was highest when sites were paired and terraintype was included as a factor in the analysis. Precision ofthe estimated difference in mean richness was nearly doubledusing the terrain-based, paired site design in comparison toother evaluated designs. Use of this method allowed us tosample stream communities representative of park-wide forestconditions while effectively controlling for landscapevariability.     

基于灰局势决策的火灾形势评价方法

简要介绍灰局势决策的基本原理。以灰局势决策的多目标方案选优思想为基础,运用灰局势决策中统一效果测度的计算方法,对火灾统计数字进行灰处理。通过对反映火灾形势的4项基本指数进行测度变换、测度运算等处理,将原先相对独立的统计数字统一到一个可以涵盖原有数据有效信息的单一测度之下,从而得到一个可以评价各参评时段之间相对火灾形势的综合指标,以此为依据实现了对火灾形势的综合评价。结合实例,具体说明基于灰局势决策的火灾形势评价方法的操作过程。     

AN EVALUATION OF PHYSICAL STREAM HABITAT ATTRIBUTES USED TO MONITOR STREAMS1

ABSTRACT: The last few decades have seen an increased reliance on the use of stream attributes to monitor stream conditions. The use of stream attributes has been criticized because of variation in how observers evaluate them, inconsistent protocol application, lack of consistent training, and the difficulty in using them to detect change caused by management activity. In this paper, we evaluate the effect of environmental heterogeneity and observer variation on the use of physical stream attributes as monitoring tools. For most stream habitat attributes evaluated, difference among streams accounted for greater than 80 percent of the total survey variation. To minimize the effect that variation among streams has on evaluating stream conditions, it may be necessary to design survey protocols and analysis that include stratification, permanent sites, and/or analysis of covariance. Although total variation was primarily due to differences among streams, observers also differed in their evaluation of stream attributes. This study suggests that if trained observers conducting a study that is designed to account for environmental heterogeneity can objectively evaluate defined stream attributes, results should prove valuable in monitoring differences in reach scale stream conditions. The failure to address any of these factors will likely lead to the failure of stream attributes as effective monitoring tools.     

Application of Sample Selection Model in Estimating Response Functions for Nitrate Percolation

The Seymour aquifer region of Texas has been identified as containing elevated levels of nitrate in ground water. Various state and federal agencies are currently studying policy options for the region by gathering more site-specific information. However, because of lack of sufficient information, cause and effect relationships between water quality and agricultural practices have not been well established for the region. Some recently available biophysical simulation models have impressive capabilities in generating large amounts of data on environmental pollution resulting from agricultural production practices. In this study, the data generated by a biophysical simulation model were used to estimate the nitrate percolation response functions for the Seymour aquifer region. Interestingly, nitrate percolation values obtained from simulation models often comprise acensoredsample because the non-zero percolation values are only observed under certain climatic events and input levels. It has been shown in the econometric literature that the use of Ordinary Least Squares (OLS) on censored sample data produces biased and inconsistent parameter estimates. Thus, a sample selection model was used in this study to estimate the response functions for nitrate percolation. The study provides some insight into the relationship between nitrate percolation and agricultural production practices. In particular, the study demonstrates the potential of selected design standards in minimizing agricultural nonpoint-source (NPS) pollution for the study area.     

催化光度法测定环境样品中微量Hg的研究

在酸性介质中,痕量Ｈｇ（Ⅱ）能显著催化空气中的Ｏ２氧化Ｋ４［Ｆｅ（ＣＮ）６］,生成蓝色化合物,反应对Ｈｇ（Ⅱ）为一级,催化反应的表观活化能为６２．９５ｋＪ·ｍｏｌ－１．据此建立了测定痕量Ｈｇ（Ⅱ）的动力学分析法,测定条件为Ｋ４［Ｆｅ（ＣＮ）６］：１．４×１０－３ｍｏｌ·Ｌ－１,［ＣＨ３ＣＯＯＨ］：０．１４ｍｏｌ·Ｌ－１,７５℃．在此条件下,线性测定范围为０．０２—０．７０μｇ·ｍｌ－１．本法重现性好,常见共存离子中除Ａｇ（Ｉ）严重干扰外,其余离子不影响测定．测定了水样及污泥样品中的Ｈｇ含量,结果满意     

连续流动分析法测定水中的CODCr

采用连续流动分析技术对环境水样中的CODCr进行大批量快速测定 ,与国标法 (重铬酸钾法 )有可比性 ,分析结果具有良好的准确性和重现性 ,方法检出限 1 3,对标准样品分析的准确度在 98%以上 ,变异系数在 0 2 1%～ 1 0 0 %之间 ,实际水样的检测结果与重铬酸钾法的相对偏差为 0 4 %～ 1 4 % ,环境水样和工业废水的加标回收率为 93%～10 1%。     

水样品中挥发酚的测量不确定度的评定方法

根据环境监测的要求,中国石油集团安全环保技术研究院实验室在出具数据时要对测量结果进行测量不确定度评定。用实例建立了分光光度法测定水样品中挥发酚的合成标准不确定度的数学模式,它由质量的标准测量不确定度和体积的标准测量不确定度组成;并对这两部分标准不确定度的分量作了详尽的分析和计算。得出测量扩展不确定度结果。