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Using a modified extraction procedure, the effect of pH on the leaching of selected elements from Ca-rich (Type C) power plant fly ash was studied. Continuous additions of acetic acid were used to maintain pH values of fly ash slurries at 4.0, 6.0 and 8.0 for 24 h and an additional set was leached at its natural pH (average 11.8) value. Analyses for Se, As, Ca, Cd, Cr, Fe, Na and Pb showed that the highest concentrations occur in the leachate at pH 4.0 and decline with increasing pH. Concentrations of Cr and Fe increased slightly between neutral and high pH. Arsenic, Cd, Cr, Pb and Se concentrations exceeded the Environmental Protection Agency's toxicity criteria at pH 4.0. Selenium was above its toxicity level at pH values near 7 but the other elements were below their respective toxicity levels near neutral pH. Because recent studies show adverse effects of Se on aquatic life at far lower concentrations than the current Environmental Protection Agency's standard, high-Ca, power plant fly ashes represent a potentially hazardous pollutant to surface and subsurface waters. 相似文献
4.
Elemental concentration data on up to 73 individual constituents in BIR-1, DNC-1, and W-2 have been collected from 94 journal articles and technical reports. These data are summarized in consensus (mean) values with uncertainties expressed as one standard deviation. Mean values are also calculated as a function of analytical procedure and all raw data are given in the tables.
Ce rapport rassemble des données analytiques sur 73 éléments dans trois échantillons, BIR-1, DNC-1 et W-2, publiées dans 94 articles scientifiques ou rapports techniques. Quand cela a été possible, les valeurs de consensus (moyenne) sont présentées pour chaque élément avec l'incertitude exprimée un écart-type. Des valeurs moyennes en fonction des procédures analytiques sont également présentées. 相似文献
Ce rapport rassemble des données analytiques sur 73 éléments dans trois échantillons, BIR-1, DNC-1 et W-2, publiées dans 94 articles scientifiques ou rapports techniques. Quand cela a été possible, les valeurs de consensus (moyenne) sont présentées pour chaque élément avec l'incertitude exprimée un écart-type. Des valeurs moyennes en fonction des procédures analytiques sont également présentées. 相似文献
5.
Prof. Dr. Thomas K. Rudel 《GeoJournal》1989,19(4):437-446
This paper argues that the process of establishing claims and control over resources, referred to as resource partitioning, structures frontier societies in ways which impede subsequent efforts at rural development. Conflicts over claims to resources create divisions among local elites which prevent the formation of coalitions to promote development. Struggles for control over the flow of resources out of a region cause regional development agencies to pursue transportation policies which retard development by isolating the region from all but one commercial center. A case study of resource partitioning and rural development efforts in the Ecuadorian Amazon illustrates the argument. 相似文献
6.
In recent years, artificial establishment of Spartina alterniflora marshes has become a common method for mitigating impacts to salt marsh systems. The vegetative component of artificially established salt marshes has been examined in several studies, but relatively little is known about the other aspects of these systems. This study was undertaken to investigate the infaunal community of artificially established salt marshes. Infauna were sampled from pairs of artificially established (AE) salt marshes and nearby natural marshes at six sites along the North Carolina coast. The AE marshes ranged in age from 1 yr to 17 yr. Total infaunal density, density of dominant taxa, and community trophic structure (proportions of subsurface-deposit feeders, surface-deposit and suspension feeders, and carnivores) were compared between the two types of marsh to assess infaunal community development in AE marshes. Overall, the two marsh types had similar component organisms and proportions of trophic groups, but total density and densities within trophic groupings were lower in the AE marshes. Soil organic matter content of the natural marshes was nearly twice that of the AE marshes, and is a possible cause for the higher infaunal densities observed in the natural marshes, Using the same three criteria, comparisons of the natural and AE marshes at each of the six locations revealed varying degrees of similarity. Similarity of each AE marsh to its natural marsh control appeared to be influenced by differences in environmental factors between locations more than by AE marsh age. Functional infaunal habitat convergence of an AE marsh with a natural marsh somewhere within its biogeographical region is probable, but success in duplicating the infaunal community of a particular natural marsh is contingent upon the developmental age of the natural marsh and the presence and interaction, of site-specific factors. 相似文献
7.
Concentration data on 73 individual constituents in United States Geological Survey (USGS) Geochemical Exploration Reference Materials GXR-1 to GXR-6 have been collected from 131 journal articles and technical reports. These data are summarized as consensus (mean) values with uncertainties expressed as one standard deviation. Mean values are also calculated as a function of analytical procedure and all raw data are given in the tables. Recommended values are proposed based upon data criteria used by NIST (National Institute of Standards and Technology, formerly the National Bureau of Standards or NBS). 相似文献
8.
Ernest S. GLADNEY Elizabeth A. JONES Eric J. NICKELL Iwan ROELANDTS 《Geostandards and Geoanalytical Research》1990,14(2):209-359
Concentration data on up to 82 individual constituents in USGS Basalt BCR-1 have been collected from 1395 journal articles and technical reports. These data are summarized in consensus (mean) values with uncertainties expressed as ± one standard deviation. Mean values are also calculated as a function of analytical procedure and all raw data are given in the tables. Recommended values are proposed based upon data criteria used by NIST (National Institute of Standards and Technology, formerly the National Bureau of Standards or NBS). 相似文献
9.
Ernest S. GLADNEY Colleen E. BURNS Iwan Roelandts 《Geostandards and Geoanalytical Research》1985,9(1):35-68
Concentration data for as many as 72 constituents in the four Canadian Certified Reference Materials Project (CCRMP) soil samples have been collected from journal articles and technical reports published since these soil standards were issued in 1978. These data are summarized into mean +/- one standard deviation values and compared with available certification data from CCRMP. All literature data located or calculated are presented in the appendices. 相似文献
10.
Ernest S. GLADNEY David B. CURTIS Daniel R. PERRIN 《Geostandards and Geoanalytical Research》1984,8(1):43-46
Concentrations of boron in 35 silicate reference materials are measured by thermal neutron capture gamma-ray spectrometry. Results are compared for NBS, USGS, and CCRMP reference materials with values from the literature. The use of two prompt gamma facilities at Los Alamos are discussed. 相似文献