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41.
Malcolm J. R. Clark Paul H. Whitfield 《Journal of the American Water Resources Association》1994,30(6):1063-1079
ABSTRACT: Current conventions for reporting analytical results from environmental samples brings the objectives of laboratory scientists into conflict with those of environmental scientists. The objective of chemical analyses is to provide estimates of the true composition of samples. Reported results must reflect the analytical uncertainty. Current conventions require left-censoring of those results below the Limit of Detection. The objective of statistical interpretation of environmental data is to provide estimates of the characteristics of ecosystems. Such statistical analyses are often confounded by left-censoring of analytical results. We review the different points of view and propose a compromise which recognizes these conflicting perspectives. 相似文献
42.
Development of a bird integrity index: using bird assemblages as indicators of riparian condition 总被引:7,自引:0,他引:7
We describe the development of a bird integrity index (BII) that uses bird assemblage information to assess human impacts
on 13 stream reaches in the Willamette Valley, Oregon, USA. We used bird survey data to test 62 candidate metrics representing
aspects of bird taxonomic richness, tolerance or intolerance to human disturbance, dietary preferences, foraging techniques,
and nesting strategies that were affected positively or negatively by human activities. We evaluated the metric responsiveness
by plotting each one against a measure of site disturbance that included aspects of land use/land cover, road density, riparian
cover, and stream channel and substrate conditions. In addition, we eliminated imprecise and highly correlated (redundant)
metrics, leaving 13 metrics for the final index. Individual metric scores ranged continuously from 0 to 10, and index scores
were weighted to range from 0 to 100. Scores were calibrated using historical species information to set expectations for
the number of species expected under minimally disturbed conditions. Site scores varied from 82 for the least disturbed stream
reach to 8.5 for an urban site. We compared the bird integrity index site scores with the performance of other measures of
biotic response developed during this study: a fish index of biointegrity (IBI) and two benthic macroinvertebrate metrics.
The three assemblages agreed on the general level of disturbance; however, individual sites scored differently depending on
specific indicator response to in-stream or riparian conditions. The bird integrity index appears to be a useful management
and monitoring tool for assessing riparian integrity and communicating the results to the public. Used together with aquatic
indicator response and watershed data, bird assemblage information contributes to a more complete picture of stream condition. 相似文献
43.
Gary B. Kappesser 《Journal of the American Water Resources Association》2002,38(4):1069-1081
ABSTRACT: Riffles in moderately entrenched stream reaches with gradients of 2 percent to 4 percent that have received excessive sediment from upstream have a distinctly different and higher proportion of smaller mobile particles than riffles in systems that are in dynamic equilibrium. The mobile fraction on the riffle can be estimated by comparing the relative abundance of various particle sizes present on the riffle with the dominant large particles on an adjacent bar. Riffle particles smaller than the dominant large particles on the bar are interpreted as mobile. The mobile percentile of particles on the riffle is termed “Riffle Stability Index” (RSI) and provides a useful estimate of the degree of increased sediment supply to riffles in mountain streams. The RSI addresses situations in which increases in gravel bedload from headwaters activities is depositing material on riffles and filling pools, and it reflects qualitative differences between reference and managed watersheds. The RSI correlates well with other measures of stream channel physical condition, such as V and the results of fish habitat surveys. Thus, it can be used as an indicator of stream reach and watershed condition and also of aquatic habitat quality. 相似文献
44.
45.
根据社会组织中客观存在的层级结构,描述了环境监测站的层级构成及其基本职能, 认识和合理利用层级管理制度有利于内设机构的设置、合理地配置其职能并确保机构高效 运行。 相似文献
46.
工业企业厂界环境噪声监测中背景噪声监测及修正探讨 总被引:1,自引:0,他引:1
针对测量结果修正的相关要求,本文对新颁布的《工业企业厂界环境噪声排放标准》(GB12348-2008)和旧标准《工业企业厂界噪声测量方法》(GB/T12349-1990)在实际工作中的运用进行了比对、分析和探讨,并根据实际工作经验,提出了在背景噪声难以测量的一些特殊情况下的几种解决途径,主要提出噪声源声值与背景声值相差小于3dB(A)时的解决方案。 相似文献
47.
建设项目竣工环境保护验收监测对于落实“三同时”制度、实现总量控制目标、为环境监督管理提供重要技术支持具有重要意义与作用。目前,验收监测在管理体制、收费标准、成果应用等方面存在的突出问题,可通过创新管理机制、健全管理制度、提高管理水平等具体措施解决。 相似文献
48.
The geographic term "Niger Inland Delta" stands for a vast plain of approximately 40,000 km(2), which is situated in the western Sahel (Republic of Mali). The Inland Delta is affected by yearly inundation through the variable water levels of the Niger-Bani river system. Due to a good availability of (surface) water, the ecosystem at the Niger Inland Delta serves as resting place stop-over for many migrating birds and other wildlife species as well as economic base for farmers and pastoral people. To foster the sustainable usage of its natural resources and to protect this natural heritage, the entire Niger Inland Delta became RAMSAR site in 2004. This paper aims to test to which extent texture analysis can improve the quality of flood monitoring in a semi-arid environment using spatially high resolution ASAR imaging mode data. We found the Gray Level Dependence Method (GLDM) was most suitable proceeding for our data. Several statistical parameters were calculated via co-occurrence matrices and were used to classify the images in different gradation of soil moisture classes. In a second step we used additional information from spatially high resolution optical data (ASTER) to improve the separability of open water areas from moisture/vegetated areas. 相似文献
49.
The influence of use-related,environmental, and managerial factors on soil loss from recreational trails 总被引:2,自引:0,他引:2
Recreational uses of unsurfaced trails inevitably result in their degradation, with the type and extent of resource impact influenced by factors such as soil texture, topography, climate, trail design and maintenance, and type and amount of use. Of particular concern, the loss of soil through erosion is generally considered a significant and irreversible form of trail impact. This research investigated the influence of several use-related, environmental, and managerial factors on soil loss on recreational trails and roads at Big South Fork National River and Recreation Area, a unit of the U.S. National Park Service. Regression modeling revealed that trail position, trail slope alignment angle, grade, water drainage, and type of use are significant determinants of soil loss. The introduction of individual and groups of variables into a series of regression models provides improved understanding and insights regarding the relative influence of these variables, informing the selection of more effective trail management actions. Study results suggest that trail erosion can be minimized by avoiding “fall-line” alignments, steep grades, and valley-bottom alignments near streams, installing and maintaining adequate densities of tread drainage features, applying gravel to harden treads, and reducing horse and all-terrain vehicle use or restricting them to more resistant routes. 相似文献
50.
伴随着日本经济的高速发展,其水环境污染问题十分严峻,防治水污染成为日本政府在20—21世纪的重要工作之一。经过几十年的努力,日本水污染治理取得长足进展。目前日本水环境监测已经形成由水和土壤等方面组成的水循环监测体系,包括地表水、近海、湖泊、地下水和土壤等。在日本的重要环保法律法规中均有涉及水环境监测工作内容的明确法律条文,国家行政机关、地方政府和公立的科研单位在具体实施水环境质量监测过程中的职责和义务不同,水环境质量监测管理的国家行政机关以环境省为主,地方政府根据环境省制定的水环境质量标准、监测技术方法及规范,制定所辖地域的监测方案并实施监测,公立的环境科研机构在环境质量监测工作中起到重要的支撑作用。笔者概述了日本开展水环境质量监测的法律依据和监测管理情况等。 相似文献