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281.
This laboratory study explores the effect of growth substrate concentration on the anaerobic degradation of trichloroethylene (TCE) in sand packed columns. In all columns the growth substrate rapidly degraded to gas, that formed a separate phase. Biomass accumulated in the 0–4.8 cm section of the columns in proportion to the influent growth substrate concentration and biomass concentrations in the remaining sections of all columns were similar to the column receiving the lowest substrate concentration. Increases in growth substrate concentration up to 3030 mg-COD l−1 promoted TCE degradation, but a further increase to 14 300 mg-COD l−1 reduced the amount of TCE completely dechlorinated but did not affect the production of chlorinated TCE intermediates. The mathematical model developed here satisfactorily described the enhancement in TCE dehalogenation for substrate concentration up to 3030 mg-COD l−1; reproducing TCE dehalogenation for 14 300 mg-COD l−1 required that the moisture content used in simulation be lowered to 0.1. The study shows that volatilization of TCE can be significant and volatilization losses should be taken into account when anaerobic activity in in-situ bioremediation applications is stimulated via addition of growth substrates. An implication of the modeling simulations is that maintaining a lower, but uniform, substrate concentration over the contaminated region may lead to faster contaminant degradation. 相似文献
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Climis A. Davos Walter A. Thistlewaite Eugene C. Paik 《Journal of environmental management》1993,37(4)
The ranking of air quality control measures according to a number of evaluation criteria and with the participation of a large number of interested publics is demonstrated. A pilot study for the South Coast Air Quality Management District of California serves as the reference point. Several methodological considerations are addressed, such as: (a) the enhancement of criterion priorities to account for the variability among the performance of the control measures when incommensurable impact levels are applied: (b) the derivation of alternative rankings according to the priorities of potential coalitions; (c) the assessment of the potential acceptability of a collective ranking given the degree of solidarity among participants with similar interest affiliations; and (b) the assessment of the extent to which the performance of specific control measures may override priority differences and lead to insignificant ranking differences. 相似文献
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Walter A. Kolb 《Environment international》1980,3(5):411-416
The environmental radioactivity surveillance program of the Federal Republic of Germany is briefly described. Some results of intercomparative measurements carried out by the Federal Milk Research Institute are presented. 相似文献
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Land use changes which affect the hydrological cycle encompass a broad field of agricultural, forestry, and engineering activity. A variety of research methods, ranging from the very simple to the very complex, have been used in attempting to evaluate the effects of such changes. Because of the complexity of the hydrological process, it is difficult to distinguish the effects of changes in land use from natural variations in quality, quantity, peak rates, and other characteristics of runoff. The use of plots, experimental catchments, barometer watersheds, representative basins, benchmark and vigil networks, and other methods for the collection of data, and methods of data analysis ranging from simple graphical correlations to multivariate analysis and mathematical catchment models are reviewed and classified. Current methods of research are mainly of an ad hoc nature and the major deficiency is in the study of fundamental physical processes. 相似文献
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This paper seeks to verify the usefulness of selected multivariate statistical techniques for exploring new dose-response relationships between human health and air pollution. We do so by comparing our results with those already established in the literature through hypothesis testing procedures or laboratory work. This use of multivariate techniques is pretheoretical and should be interpreted as suggesting relationships which warrant further investigation with more traditional methodologies. Our results conform very well with those existing in the literature and lend credence to the use of such pretheoretical statistical methods. 相似文献