海岸地下水勘探的地面电阻率法

地面电阻率法能探测孔隙水含盐量的变化，对海岸地下水的勘探有重要作用。电阻率的解释要与海岸的水文地质模型相吻合。在解释潜水含水层的电阻率时，应当注意包气带的下部边界是潜水面，而是毛细带顶部，淡水层的下部边界不是过渡带中部，而是过渡带顶部。地面电阻率法能定量确定淡水层的埋深、厚度和分布范围。     

国家气象局强风暴实验室1991年度学术报告会在北京举行

国家气象局部门重点开放实验室——强风暴实验室(SSL)1991年度学术报告会于1992年3月10日至12日在北京举行。有70多位专家、学者参加会议,收到学术论文29篇。内容涉及到中尺度天气动力学和大气物理学,中尺度数值模拟和数值预报,以及遥感资料的综合分析和应用等,取得了一批有价值的科研成果。部分成果居国内领先水平和世界先进水平。     

蒙大拿州Beartooth山脉北Snowy地块的太古代构造

位于蒙大拿州Beartooth山脉北西部的北Snowy地块主要是由七个太古代岩性单元组成:(1)Mouny Cowen眼球状花岗质片麻岩;(2)由大量长英质片麻岩、砂屑片岩、角闪岩和铁建造组成的副片麻岩系;(3)眼球状构造的花岗质凝灰岩;(4)千枚状Dauis Geeek片岩;(5)奥长花岗质片麻岩—角闪石岩杂岩;(6)Pine Greek推覆杂岩,为一具有闪岩核和两翼对称出现大理岩和石英岩的区域等斜构造;(7)上壳混合杂岩,由石英岩—闪岩组合和具有花岗质物质间层贯入上壳岩的非均质片麻岩组成。每个单元有其特征的岩性组合、变质级和构造样式。大多数单元之间的接触部位以糜棱岩(被认为是韧性断层的产物)和变质级的突变为标志。在四个构造作用最强的单元中,这些变化造成变质级的逆向和不连续增加。这些单元现在的轮廓最好解释为,在2.74Ga和2.56Ga前,变质期后,可能沿走向滑移断层和逆冲断层的构造拼合。从更大的范围看,这一地区位于怀俄明州北部两个截然不同地体的边界上(副片麻岩—Mount Cowan接触)。一个为东西的晚太古代侵入地体。另一个是西面的太古代变质上壳岩地体。NSB和Beartooth山脉的其它部分的关系表明,这个边界产生在晚太古代造山运动期间,与现代碰撞环境有许多相似性。     

探空资料在微波辐射计资料处理中的应用

本文介绍了在微波辐射计资料处理中探空资料的选取及处理方法,水汽和云水含量的计算,判云标准的建立和理论亮温的计算。交叉反演系数选择的反演方法大大提高了反演精度和资料处理的全天候能力。     

地球物理反问题中的总体推断

浅部地球的非侵害研究是众多地球科学学科的一个基本环节。这种研究通常用地球物理方法来完成，这意味着要求解地球物理反问题。遗憾的是，几乎所有的地球物理反问题都有固有的非唯一性。本文描述了一种处理非唯一性的方法，可以相信该方法比这个领域中以前的方法更直接更完善，我们不采用正则化方法来约束问题的非唯一性，而是直接针对非唯一性并描述它。基本方法是产生并描述一个模型集，该集根据观测误差在可接受的限制范围内拟合数据。为表征解的不确定性和推断所有可接受模型的共性，用统计方法来分析这个也称为总体的模型集。另外该方法也给出问题线性程度的信息和制定各参数间的折衷方案。该方法具有普遍性，能用于众多地球物理反问题。我们用两个典型的地球物理反问题说明了这个方法。第一是加利福尼亚州Ｋｅｓｔｅｒｓｏｎ的跨孔走时应用。第二个应用由地面重力测量同时估计常数密度体的密度和形状。     

Measuring and monitoring persistent organic pollutants in the context of risk assessment

Due to growing concerns regarding persistent organic pollutants (POPs) in the environment, extensive studies and monitoring programs have been carried out in the last two decades to determine their concentrations in water, sediment, and more recently, in biota. An extensive review and analysis of the existing literature shows that whilst the vast majority of these efforts either attempt to compare (a) spatial changes (to identify "hot spots"), or (b) temporal changes to detect deterioration/improvement occurring in the environment, most studies could not provide sufficient statistical power to estimate concentrations of POPs in the environment and detect spatial and temporal changes. Despite various national POPs standards having been established, there has been a surprising paucity of emphasis in establishing accurate threshold concentrations that indicate potential significant threats to ecosystems and public health. Although most monitoring programs attempt to check compliance through reference to certain "environmental quality objectives", it should be pointed out that many of these established standards are typically associated with a large degree of uncertainty and rely on a large number of assumptions, some of which may be arbitrary. Non-compliance should trigger concern, so that the problem can be tracked down and rectified, but non-compliance must not be interpreted in a simplistic and mechanical way. Contaminants occurring in the physical environment may not necessarily be biologically available, and even when they are bioavailable, they may not necessarily elicit adverse biological effects at the individual or population levels. As such, we here argue that routine monitoring and reporting of abiotic and biotic POPs concentrations could be of limited use, unless such data can be related directly to the assessment of public health and ecological risks. Risk can be inferred from the ratio of predicted environmental concentration (PEC) and the predicted no effect concentration (PNEC). Currently, the paucity of data does not allow accurate estimation of PNEC, and future endeavors should therefore, be devoted to determine the threshold concentrations of POPs that can cause undesirable biological effects on sensitive receivers and important biological components in the receiving environment (e.g. keystone species, populations with high energy flow values, etc.), to enable derivation of PNECs based on solid scientific evidence and reduce uncertainty. Using the threshold body burden of POPs required to elicit damages of lysosomal integrity in the green mussel (Perna virvidis) as an example, we illustrate how measurement of POPs in body tissue could be used in predicting environmental risk in a meaningful way.     

Measuring segregation: an activity space approach

While the literature clearly acknowledges that individuals may experience different levels of segregation across their various socio-geographical spaces, most measures of segregation are intended to be used in the residential space. Using spatially aggregated data to evaluate segregation in the residential space has been the norm and thus individual’s segregation experiences in other socio-geographical spaces are often de-emphasized or ignored. This paper attempts to provide a more comprehensive approach in evaluating segregation beyond the residential space. The entire activity spaces of individuals are taken into account with individuals serving as the building blocks of the analysis. The measurement principle is based upon the exposure dimension of segregation. The proposed measure reflects the exposure of individuals of a referenced group in a neighborhood to the populations of other groups that are found within the activity spaces of individuals in the referenced group. Using the travel diary data collected from the tri-county area in southeast Florida and the imputed racial–ethnic data, this paper demonstrates how the proposed segregation measurement approach goes beyond just measuring population distribution patterns in the residential space and can provide a more comprehensive evaluation of segregation by considering various socio-geographical spaces.     

Evaluation of sewage source and fate on southeast Florida coastal reefs

Water, sponge and coral samples were collected from stations impacted by a variety of pollution sources and screened for human enteric viruses as conservative markers for human sewage. While human enteroviruses and adenoviruses were not detected, noroviruses (NoV; human genogroups I and II) were detected in 31% of samples (especially in sponge tissue). Stations near inlets were the only ones to show multiple sample types positive for NoV. Fecal indicator bacteria and enteric viruses were further evaluated at multiple inlet stations on an outgoing tide. Greatest indicator concentrations and highest prevalence of viruses were found at the mouth of the inlet and offshore in the inlet plume. Results suggest that inlets moving large volumes of water into the coastal zone with tides may be an important source of fecal contaminants. Efforts to reduce run-off or unintended release of water into the Intracoastal Waterway may lower contaminants entering sensitive coastal areas.