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排序方式: 共有3200条查询结果,搜索用时 15 毫秒
21.
Paul Pinsky Matthew Lorber Kent Johnson Burton Kross Leon Burmeister Amina Wilkins George Hallberg 《Environmental monitoring and assessment》1997,47(2):197-221
In 1988, the Iowa Department of Natural Resources, along withthe University of Iowa, conducted the Statewide Rural WellWater Survey, commonly known as SWRL. A total of 686private rural drinking water wells was selected by use of aprobability sample and tested for pesticides and nitrate. A subsetof these wells, the 10% repeat wells, were additionally sampledin October, 1990 and June, 1991. Starting in November, 1991,the University of Iowa, with sponsorship from the United StatesEnvironmental Protection Agency, revisited the 10% repeat wellsto begin a study of the temporal variability of atrazine and nitratein wells. Other wells, which had originally tested positive foratrazine in SWRL but were not in the 10% population, wereadded to the study population. Temporal sampling for a year-long period began in February of 1992 and concluded in Januaryof 1993. All wells were sampled monthly, a subset was sampledweekly, and a second subset was sampled for 14 day consecutiveperiods. Of the 67 wells in the 10% population tested monthly,7 (10.4%) tested positive for atrazine at least once during theyear, and 3 (4%) were positive each of the 12 months. Theaverage concentration in the 7 wells was 0.10 µg/L. Fornitrate, 15 (22%) wells in the 10% repeat population monthlysampling were above the Maximum Contaminant Level of 10 mg/L at least once. This paper, the second of two papers on thisstudy, describes the analysis of data from the survey. The firstpaper (Lorber et al., 1997) reviews the study design, theanalytical methodologies, and development of the data base. 相似文献
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Environmental audits: Proposed terminology 总被引:1,自引:0,他引:1
This paper presents a review of the fast developing subject of environmental auditing with the authors proposing a series of definitions. Of particular concern is a move towards the development of an accepted vocabulary for environmental impact assessment, even though the international dimension of the subject makes this a difficult task. Use of the word audit has become an accepted part of EIA vocabulary, however there are several types of audits being undertaken today. Presently, there are no commonly accepted definitions, consequently this paper will attempts to address this issue. Definitions for seven types of environmental audits are suggested, derived from the experience of the authors and from a review of the current literature. It is hoped that by the presentation of these definitions that such terms will be advocated for future EIA work, and thereby reducing confusion that otherwise may occur. The paper concludes with a brief review of the status of auditing. 相似文献
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Material within the terrestrial environment is rarely homogeneously distributed, either spatially or temporally. One consequence of heterogeneity is that uncertainty is usually generated in measurements that are taken with the aim of characterising the environment. For example, a measurement of analyte concentration within soil taken from one sampling location on contaminated land can vary substantially when compared against another sample taken at effectively the same nominal location. The measurement uncertainty arising from the heterogeneity can substantially limit the reliability of the interpretations made upon environmental investigations. The sampling uncertainty usually outweighs the analytical uncertainty from the laboratory, often by a factor of 20 or more. One approach to reducing the uncertainty is to design a more suitable sampling strategy. This might be achieved by predicting the degree of heterogeneity prior to the investigation, but this is often difficult to achieve accurately. Another approach, which was investigated here, is to actually characterise the heterogeneity prior to the main investigation using rapid and inexpensive technology, such as in situ measurement techniques. In situ portable X-ray fluorescence (PXRF) and X-ray microprobe (XMP) techniques were employed to test the feasibility of this approach. Two contrasting contaminated land sites were chosen to characterise the two-dimensional spatial heterogeneity of heavy metal contamination in topsoil at a range of scales (50 m to 0.001 m). The spatial heterogeneity of contaminants, expressed as relative standard deviations, was found to differ between the two sites by a factor of two, largely due to the mode of deposition of pollution. The study also indicated that the heterogeneity did not change systematically with the scale of measurement between sampling locations at either site. 相似文献
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Paul Uvebrant Eva Björck Nils Conradi Klas-Henry Hökegård Tommy Martinsson Jan Wahlström 《黑龙江环境通报》1993,13(7):651-657
A family with two siblings, 10 and 8 years old, both with clinical and ultrastructural evidence of juvenile neuronal ceroid lipofuscinosis is described. The family was found to be informative for the restriction fragment length polymorphisms (RFLPs) detected by the probes pCJ52–95Ml (locus D16S148) and pCJ52-94Tl (locus D16S159) flanking the juvenile neuronal ceroid lipofuscinosis locus, CLN3. The parents were both heterozygous using these probes, while their two children with juvenile neuronal ceroid lipofuscinosis were both homozygous. Chorionic villi analysis showed that the fetus was heterozygous and had inherited the one allele of the mother which was not found in the two siblings. This suggested that the fetus had derived one healthy allele from the mother, the risk for a double crossing-over being less than 1 per cent. Electron microscopy showed no fingerprint inclusions in chorionic villi. The child was investigated at 6 months of age and found to be healthy, as new fingerprint inclusions were found at electron microscopy and no vacuolated lymphocytes were found in the blood smear. Due to the risk of heterogeneity, both DNA-based analysis and electron microscopy on chorionic villi are recommended for prenatal examination for juvenile neuronal ceroid lipofuscinosis. 相似文献
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Determinationofpolychlorinatedbiphenylcongenersinenvironmentalsamples¥ChuShaogang;YangChun;XuXiaobai(ResearchCenterforEco-Env... 相似文献