26 research outputs found
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Sorption of radioactive contaminants by sediment from the Kara Sea
The purpose of this study is to quantify some of the parameters needed to perform near-field modeling of sites in the Kara Sea that were impacted by the disposal of radioactive waste. The parameters of interest are: the distribution coefficients (K{sub d}) for several important radionuclides, the mineralogy of the sediment, and the relationship of K{sub d} to liquid to solid ratio. Sediment from the Kara Sea (location: 73{degrees} 00` N, 58{degrees} 00` E) was sampled from a depth of 287 meters on August 23/24, 1992, during a joint Russian/Norwegian scientific cruise. Analysis of the material included mineralogy, grain size and total organic carbon. Uptake kinetics were determined for {sup 85}Sr, {sup 99}Tc, {sup 125}I, {sup 137}Cs, {sup 210}Pb, {sup 232}U, and {sup 241}Am and distribution coefficients (K{sub d}) were determined for these radionuclides using batch type experiments. Sorption isotherms were developed for {sup 85}Sr, {sup 99}Tc, and {sup 137}Cs to examine the effect that varying the concentration of a tracer has on the quantity of that tracer taken up by the solid. The effect of liquid to solid ratio on the uptake of contaminants was determined for {sup 99}Tc and {sup 137}Cs. In another set of experiments, the sediment was separated into four size fractions and uptake was determined for each fraction for {sup 85}Sr, {sup 99}Tc, and {sup 137}Cs. In addition, the sediment was analyzed to determine if it contains observable concentrations of anthropogenic radionuclides
Estuarine clay mineral distribution:Modern analogue for ancient sandstone reservoir quality prediction
The spatial distribution of clay minerals in sandstones, which may both enhance or degrade reservoir quality, is poorly understood. To address this, clay mineral distribution patterns and host‐sediment properties (grain size, sorting, clay fraction abundance and bioturbation intensity) have, for the first time, been determined and mapped at an unprecedentedly high‐resolution in a modern estuarine setting (Ravenglass Estuary, UK). Results show that the estuary sediment is dominated by illite with subordinate chlorite and kaolinite, although the rivers supply sediment with less illite and significantly more chlorite than found in the estuary. Fluvial‐supplied sediment has been locally diluted by sediment derived from glaciogenic drift deposits on the margins of the estuary. Detailed clay mineral maps and statistical analyses reveal that the estuary has a heterogeneous distribution of illite, chlorite and kaolinite. Chlorite is relatively most abundant on the northern foreshore and backshore and is concentrated in coarse‐grained inner estuary dunes and tidal bars. Illite is relatively most abundant (as well as most crystalline and most Fe–Mg‐rich) in fine‐grained inner estuary and central basin mud and mixed flats. Kaolinite has the highest abundance in fluvial sediment and is relatively homogenous in tidally‐influenced environments. Clay mineral distribution patterns in the Ravenglass Estuary have been strongly influenced by sediment supply (residence time) and subsequently modified by hydrodynamic processes. There is no relationship between macro‐faunal bioturbation intensity and the abundance of chlorite, illite or kaolinite. Based on this modern‐analogue study, outer estuarine sediments are likely to be heavily quartz cemented in deeply‐buried (burial temperatures exceeding 80 to 100°C) sandstone reservoirs due to a paucity of clay grade material (<0·5%) to form complete grain coats. In contrast, chlorite‐enriched tidal bars and dunes in the inner estuary, with their well‐developed detrital clay coats, are likely to have quartz cement inhibiting authigenic clay coats in deeply‐buried sandstones
Corporate philanthropy and corporate financial performance: The roles of social response and political access
Corporate philanthropy is expected to positively affect firm financial performance because it helps firms gain sociopolitical legitimacy, which enables them to elicit positive stakeholder responses and to gain political access. The positive philanthropy-performance relationship is stronger for firms with greater public visibility and for those with better past performance, as philanthropy by these firms gains more positive stakeholder responses. Firms that are not government-owned or politically well connected were shown to benefit more from philanthropy, as gaining political resources is more critical for such firms. Empirical analyses using data on Chinese firms listed on stock exchanges from 2001 to 2006 support these arguments
Corporate philanthropic giving, advertising intensity, and industry competition level
This article examines whether the likelihood and amount of firm charitable giving in response to catastrophic events are related to firm advertising intensity, and whether industry competition level moderates this relationship. Using data on Chinese firms' philanthropic response to the 2008 Sichuan earthquake, we find that firm advertising intensity is positively associated with both the probability and the amount of corporate giving. The results also indicate that this positive advertising intensity-philanthropic giving relationship is stronger in competitive industries, and firms in competitive industries are more likely to donate. This study thus provides evidence suggesting that even in the wake of catastrophic events, corporate philanthropic giving is strategic.BusinessEthicsSSCI23ARTICLE139-529
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Partitioning between sediment and porewater of radiocesium from Chernobyl fallout
As part of a joint USA/USSR Environmental Agreement to determine the distribution and concentration of Chernobyl radioactivity in the northwest Black Sea area, the sediment from eight stations was collected and analyzed to assess the ability of sediment from the northwest Black Sea to adsorb radiocesium. Two methods were used to determine partitioning between liquid and solid phases; batch tests and porewater separation. In the batch test, Cs-137 tracer was added to mixtures of sediment and bottom water, with contact solutions ranging from 85 Bq/ml to 1760 Bq/ml. The distribution ratios (R{sub D}) for individual batch tests ranged from 390 to 1770 ml/g. Isotherms were linear for all cores and R{sub D} values calculated from the slopes of the isotherms ranged from 660 to 1660 ml/g. A second approach was used to determine the partitioning of Cs-137 between the porewater and the sediment under more natural conditions. The top 2 cm of two cores were sectioned and the sediment and the porewater were separated. In both samples the sediment contained significant amounts of Cs-137 and Cs-134 indicating the presence of fallout from the Chernobyl reactor accident. There was no cesium activity observed in the porewater at a minimum detectable level of 0,008 Bq/ml. 32 refs., 5 figs., 7 tabs