伊犁河(中国段)水质模糊综合分析

根据伊犁河 (中国段 )多年水质监测资料 ,运用模糊数学方法分析伊犁河水质模糊综合指数的时空分布特征及其相关关系 ,掌握了伊犁河 (中国段 )水质现状和污染状况。     

利用曲线补偿变时溶出示差技术测定Cu、Pb、Zn、Cd初步探讨

本文利用曲线补偿,变时溶出示差技术提高了测定Ｃｕ、Ｐｂ、Ｚｎ、Ｃｄ的灵敏度、精密度和准确度,进一步改变了谱图的分辨率,避免了Ｏ２波的干扰     

南京市黑碳气溶胶时间演变特征及其主要影响因素

为了研究南京市黑碳(black carbon,BC)气溶胶的时间演变特征及其主要影响因素,使用多波长Aethalometer(AE-33)每个季节选取典型月份观测了BC质量浓度,结合大气污染物数据、气象要素和边界层探测数据,分析了BC的季节变化、日变化、周末效应和来源特征.结果表明,南京的BC浓度具有明显的季节变化,春季[(3 351±919) ng·m^-3]>冬季[(3 234±2102) ng·m^-3]>秋季[(3 064±967) ng·m^-3]>夏季[(2 632±1 705) ng·m^-3]. 4个季节BC日变化均为双峰型分布,峰值分别位于06:00～08:00和21:00～23:00. BC不同季节的早晚高峰分布特征不同.早高峰春季BC浓度最高,晚高峰冬季浓度最高.冬季早高峰出现时间要比其他季节滞后2 h,而夏季晚高峰时间反而比其他季节提前2 h.风速对BC日变化季节分布差异的影响远大于相对湿度(relative humidity,RH).逆温层结对大气污染物浓度的影响...     

重构土壤垂直剖面重金属Cd赋存形态及影响因素

针对矿业废弃地高背景值-历史矿业源相叠加区下土壤重金属Cd污染问题,以西南地区某历史硫磺矿业废弃地重构土壤为研究对象,采集剖面土壤共30个样品,分析测试土壤样品中镉(Cd)、铬(Cr)、镍(Ni)、砷(As)和汞(Hg),利用电镜扫描-能谱分析(SEM-EDS)和重金属形态连续提取的BCR方法,分析不同土层厚度下Cd的赋存形式,运用风险评价编码法(RAC)和次生相与原生相分布比值法(RSP)对其进行有效性评价,以及对不同理化性质下Cd各形态的变化规律进行了初步探讨.结果表明,研究区5种重金属中Cd全量的富集系数最高,达4以上;通过形貌特征可以发现,样品中存在较多的次棱角状、棱角状颗粒,不同深度下的能谱特征显示结果相似,均含有Cd、Fe、S和As等元素,Cd元素是以类质同象形式存在;对Cd进行潜在风险评价,RAC结果显示为中等风险及以下,RSP结果主要为重度污染;重金属全量是影响Cd各形态含量分布的最主要因素,其次pH、有机质和CEC,对垂直深度的土壤Cd赋存形态也表现出不同程度的影响.该研究结果可为进一步了解Cd在剖面土壤的活性、迁移规律、生物毒性和赋存形式提供科学依据.     

中国第1个天线时域近场测量系统

介绍了天线近场测量的历史以及中国第1个天线时域近场测量系统的建立过程和系统组成.指出时基修正和幅度修正技术是天线近场测量由理论向工程实际转化的关键技术,介绍了修正系统的构成和基本计算方法,并给出了修正前后测量结果的对比.在频域近场技术的背景下对时域近场的技术特点进行了分析,指出了天线时域近场测量技术的独到之处和应用前景.     

Incorporating detectability of threatened species into environmental impact assessment

Environmental impact assessment (EIA) is a key mechanism for protecting threatened plant and animal species. Many species are not perfectly detectable and, even when present, may remain undetected during EIA surveys, increasing the risk of site‐level loss or extinction of species. Numerous methods now exist for estimating detectability of plants and animals. Despite this, regulations concerning survey protocol and effort during EIAs fail to adequately address issues of detectability. Probability of detection is intrinsically linked to survey effort; thus, minimum survey effort requirements are a useful way to address the risks of false absences. We utilized 2 methods for determining appropriate survey effort requirements during EIA surveys. One method determined the survey effort required to achieve a probability of detection of 0.95 when the species is present. The second method estimated the survey effort required to either detect the species or reduce the probability of presence to 0.05. We applied these methods to Pimelea spinscens subsp. spinescens, a critically endangered grassland plant species in Melbourne, Australia. We detected P. spinescens in only half of the surveys undertaken at sites where it was known to exist. Estimates of the survey effort required to detect the species or demonstrate its absence with any confidence were much higher than the effort traditionally invested in EIA surveys for this species. We argue that minimum survey requirements be established for all species listed under threatened species legislation and hope that our findings will provide an impetus for collecting, compiling, and synthesizing quantitative detectability estimates for a broad range of plant and animal species. Incorporación de la Capacidad de Detectar una Especie Amenazada a la Evaluación de Impacto Ambiental     

超高速活性污泥法的试验研究

吸附活性污泥法是一种高效率的污水处理方法，曝气池停留时间约４０ｍｉｎ、ＣＯＤ、ＢＯＤ５和ＳＳ的去除率可达到６０－７０％。本文以试验结果为基础，探讨了停留时间，污泥浓度，污泥回流比和污浓度对处理效果的影响，也探讨了该方法对氮，磷的去除效果。     

APPLICATION OF INFILTRATION THEORY FOR THE DETERMINATION OF EXCESS RAINFALL HYETOGRAPH1

ABSTRACT: The purpose of this paper is to show through the use of numerical examples that modern infiltration theory can be used in everyday hydrologic practice. The actual use of four methods of calculation of infiltration rates and of excess rainfall rates is demonstrated for the case when simultaneous data of rainfall and stream flow are available for a watershed. The four methods are: (1) the well known Π-index method, (2) the traditional Horton's infiltration capacity formula, (3) the less traditional Green and Ampt infiltration capacity formula, and (4) a ponding time approach. It is recommended that hydrologists become at least familiar with the numerical procedures involved in the ponding time and postponding infiltration approach. This approach, though not flawless, should be preferred to the other three methods if use of the other three is at all considered.     

SOME SIMPLE MODELS FOR CONTINUOUS VARIATE TIME SERIES1

ABSTRACT: A survey is given of recently developed models for continuous variate non–Gaussian time series. The emphasis is on marginally specific models with given correlation structure. Exponential, Gamma, Weibull, Laplace, Beta and Mixed Exponential models are considered for the marginal distributions of the stationary time series. Most of the models are random coefficient, additive linear models. Some discussion of the meaning of autoregression and linearity is given, as well as suggestions for higher–order linear residual analysis for non–Gaussian models.     

THE OPPORTUNITY COST OF TIME AND AVERTING EXPENDITURES FOR SAFE DRINKING WATER1

ABSTRACT: A survey of individuals during a Giardia contamination incident provided data to calculate the cost of boiling, hauling, or purchasing water to avoid infection. Three different approaches to the valuation of time were used to assess the implications of the opportunity cost of time for the measurement of averting costs. Mean monthly household averting costs were $33.47 using family income to value time, $13.07 using the minimum wage to value time, and $5.60 using zero opportunity cost of time. Comparisons of the mean costs for different sources and household characteristics indicated the value of time from family income was too high and that the other methods of valuing time were superior.