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841.
Statistical evaluation of the influence of flow conditions and sampling techniques on water quality data. 总被引:1,自引:0,他引:1
The purpose of this study is to statistically evaluate the influence of various sampling methodologies and flow conditions on the quality and comparability of total phosphorus concentration data collected over the course of 27 months at the South Florida Water Management District (SFWMD) S-65E structure. The data was obtained from the following sampling methodologies: U.S. Geological Survey (USGS) (Reston, Virginia) equal width increment spatially composite grab samples, USGS replicate samples, SFWMD grab samples, and SFWMD autosampler samples. Both significant and insignificant differences were reported from these comparisons. Parametric and nonparametric standard statistical tests for significance were carried out to evaluate the differences between the data. To avoid invalid conclusions of insignificant differences, we conducted tests for equivalence of the means and variances. The results from the data analysis revealed that both flow conditions and sampling methodology affected the water quality data. 相似文献
842.
Sulfonated naphthalene formaldehyde condensates (SNFC) and their monomeric analogues were used as superplasticizers for cement suspension injections at two tunnel construction sites that are in direct contact with groundwater. Because in one case the aquifer is an important drinking water resource, the behavior of SNFC in the groundwater was carefully investigated. Chemical analyses showed that SNFC leached to the groundwater in concentrations of up to 58 microg/l of total SNFC at a distance of about 60 m down-gradient from the construction site. Of the individual SNFC components, only monomers and oligomers with up to four units could be detected in the groundwater. Oligomers with more than four units did not leach from the cement paste. The leached oligomers were transported in the groundwater at different velocities, which can be explained by sorption experiments. Mass fluxes of SNFC used at the tunnel construction sites were evaluated. Most SNFC were immobilized in the cement, but 5% (w/w) of the applied SNFC were found to leach into the aquifer. This corresponds to a total amount of leached SNFC of approximately 100 kg, of which about 80% are biodegraded in the aquifer and 20% (20 kg) still remain in the groundwater. 相似文献
843.
Mark K. Goldstein Salvador R. Bozzo Robert Malone Fernando Galdos Walter Sevian Donald Goellner 《Environmental management》1979,3(5):447-460
The data base for each process of the nuclear fuel cycle has been updated as a part of the Committee on Nuclear and Alternative Energy Systems (CONAES) at Brookhaven National Laboratory (BNL). The BNL Energy System Network Simulator (ESNS) was modified to accommodate the new data, and methodology was developed for estimating population dose and health effects resulting from atmosphere releases of radioactive materials from the nuclear fuel cycle.Estimates of population dose and health effects were made using these new CONAES emission data and the new model for three scenarios out to the year 2000: (1) no reprocessing; (2) reprocessing, 1-year cooling; and (3) reprocessing, 5-year cooling. Results indicate that radon emissions from mining and milling of uranium bearing ores will have greater impacts than any other component in the open nuclear fuel cycle. The estimated number of health effects will depend, to a large extent, on the lung model mechanism assumed to induce cancer; i.e., either the smeared or the unsmeared model. The smear model and the linear relationship predict for scenario 1, 630; for scenario 2, 949; and for scenario 3, 854 lung cancers, respectively, using the new CONAES data.Epidemiologic data from six United States counties were correlated using a new statistical model (described in the text) in order to test the validity of the lung model and the linear relationship. Results do not support the high lung cancer correlations expected from the unsmear model and the linear relationship; therefore, it is concluded that low-dose mechanisms may be different from those developed from high-dose data. The best place to look for effects of low-dose radiation may be the less developed countries because of a reduction in the noise level caused by chemical pollutants. 相似文献
844.
Ronald M. North Walter P. Neely 《Journal of the American Water Resources Association》1977,13(5):995-1005
ABSTRACT: Three basic principles of responsibility have influenced the Federal/non-Federal cost sharing rates for water resources programs (1) full payment by beneficiaries (2) exclusive Federal assumption of costs and (3) joint Federal/non-Federal sharing. The efforts to determine appropriate cost sharing rates have resulted in several hundred complex arrangements involving contributions, user charges and direct sales based on many variations of payment terms. This basic present value model was developed to determine the non-Federal cost shares which are expected to be paid for 32 different functional purposes emanating from Federal water resources programs and projects for both implementation and OMR stages. The model introduces the concept of a composite (implementation plus OMR) cost share as a focus developing appropriate cost sharing rates for the private, public and mixed outputs produced through public water resources investments. The model can be used as a focus for policy decisions on cost sharing which seek to achieve consistent and equitable cost shares for purposes provided while maintaining an efficient allocation of resources within water programs. 相似文献
845.
Walter H. Corson 《The Environmentalist》2002,22(1):67-82
Indirect, unpriced environmental and social costs of human activities in the United States amount to several trillion dollars each year. By accounting for these costs and shifting some of the tax burden from work to waste, it would be possible to protect the environment and benefit society and the economy. 相似文献
846.
847.
Heinrich Walter 《Die Naturwissenschaften》1984,71(8):387-392
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