The Experts below are selected from a list of 16185 Experts worldwide ranked by ideXlab platform
James William Carey - One of the best experts on this subject based on the ideXlab platform.
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Geochemical Method FOR IDENTIFYING ALKALI-SILICA-REACTION GEL
Transportation Research Record, 1999Co-Authors: George D Guthrie, James William CareyAbstract:A Geochemical Method for staining various products of the alkali-silica reaction is presented. The Method is based on both the composition of alkali-silica-reaction (ASR) gel and one of its properties (the ability to exchange cations with a fluid). Specifically, one stain (sodium cobalt-initrite) reacts with exchangeable potassium in the gel to form a bright-yellow precipitate on the gel surface. The other class of stains (a variety of rhodamine compounds) reacts with calcium-rich portions of the gel (and, for some compounds, with other calcium-rich components of the concrete) to form a pink-stained gel. The significance of the pink staining is twofold. First, it can provide a high contrast to the yellow-stained gels, making them easier to observe. Second, some rhodamine compounds react predominantly with Ca-rich ASR gels. Some aspects of staining by rhodamine remain the subject of continued study and may be useful for a more detailed understanding of ASR progression and other deterioration mechanisms. Ho...
Forryan Alexander - One of the best experts on this subject based on the ideXlab platform.
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Arctic freshwater fluxes: sources, tracer budgets and inconsistencies
'Copernicus GmbH', 2020Co-Authors: Forryan Alexander, Bacon Sheldon, Tsubouchi Takamasa, Torres-valdés Sinhué, Garabato, Alberto C. NaveiraAbstract:The net rate of freshwater input to the Arctic Ocean has been calculated in the past by two Methods: directly, as the sum of precipitation, evaporation and runoff, an approach hindered by sparsity of measurements, and by the ice and ocean budget Method, where the net surface freshwater flux within a defined boundary is calculated from the rate of dilution of salinity, comparing ocean inflows with ice and ocean outflows. Here a third Method is introduced, the Geochemical Method, as a modification of the budget Method. A standard approach uses Geochemical tracers (salinity, oxygen isotopes, inorganic nutrients) to compute “source fractions” that quantify a water parcel's constituent proportions of seawater, freshwater of meteoric origin, and either sea ice melt or brine (from the freezing-out of sea ice). The Geochemical Method combines the source fractions with the boundary velocity field of the budget Method to quantify the net flux derived from each source. Here it is shown that the Geochemical Method generates an Arctic Ocean surface freshwater flux, which is also the meteoric source flux, of 200±44 mSv (1 Sv=106 m3 s−1), statistically indistinguishable from the budget Method's 187±44 mSv, so that two different approaches to surface freshwater flux calculation are reconciled. The freshwater export rate of sea ice (40±14 mSv) is similar to the brine export flux, due to the “freshwater deficit” left by the freezing-out of sea ice (60±50 mSv). Inorganic nutrients are used to define Atlantic and Pacific seawater categories, and the results show significant non-conservation, whereby Atlantic seawater is effectively “converted” into Pacific seawater. This is hypothesized to be a consequence of denitrification within the Arctic Ocean, a process likely becoming more important with seasonal sea ice retreat. While inorganic nutrients may now be delivering ambiguous results on seawater origins, they may prove useful to quantify the Arctic Ocean's net denitrification rate. End point degeneracy is also discussed: multiple property definitions that lie along the same “mixing line” generate confused results.publishedVersio
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Arctic freshwater fluxes: sources, tracer budgets and inconsistencies
'Copernicus GmbH', 2019Co-Authors: Forryan Alexander, Bacon Sheldon, Tsubouchi Takamasa, Torres-valdés Sinhué, Naveira Garabato, Alberto C.Abstract:The net rate of freshwater input to the Arctic Ocean has been calculated in the past by two Methods: directly, as the sum of precipitation, evaporation and runoff, an approach hindered by sparsity of measurements, and by the ice and ocean budget Method, where the net surface freshwater flux within a defined boundary is calculated from the rate of dilution of salinity, comparing ocean inflows with ice and ocean outflows. Here a third Method is introduced, the Geochemical Method, as a modification of the budget Method. A standard approach uses Geochemical tracers (salinity, oxygen isotopes, inorganic nutrients) to compute “source fractions” that quantify a water parcel's constituent proportions of seawater, freshwater of meteoric origin, and either sea ice melt or brine (from the freezing-out of sea ice). The Geochemical Method combines the source fractions with the boundary velocity field of the budget Method to quantify the net flux derived from each source. Here it is shown that the Geochemical Method generates an Arctic Ocean surface freshwater flux, which is also the meteoric source flux, of 200±44 mSv (1 Sv=106 m3 s−1), statistically indistinguishable from the budget Method's 187±44 mSv, so that two different approaches to surface freshwater flux calculation are reconciled. The freshwater export rate of sea ice (40±14 mSv) is similar to the brine export flux, due to the “freshwater deficit” left by the freezing-out of sea ice (60±50 mSv). Inorganic nutrients are used to define Atlantic and Pacific seawater categories, and the results show significant non-conservation, whereby Atlantic seawater is effectively “converted” into Pacific seawater. This is hypothesized to be a consequence of denitrification within the Arctic Ocean, a process likely becoming more important with seasonal sea ice retreat. While inorganic nutrients may now be delivering ambiguous results on seawater origins, they may prove useful to quantify the Arctic Ocean's net denitrification rate. End point degeneracy is also discussed: multiple property definitions that lie along the same “mixing line” generate confused results
George D Guthrie - One of the best experts on this subject based on the ideXlab platform.
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Geochemical Method FOR IDENTIFYING ALKALI-SILICA-REACTION GEL
Transportation Research Record, 1999Co-Authors: George D Guthrie, James William CareyAbstract:A Geochemical Method for staining various products of the alkali-silica reaction is presented. The Method is based on both the composition of alkali-silica-reaction (ASR) gel and one of its properties (the ability to exchange cations with a fluid). Specifically, one stain (sodium cobalt-initrite) reacts with exchangeable potassium in the gel to form a bright-yellow precipitate on the gel surface. The other class of stains (a variety of rhodamine compounds) reacts with calcium-rich portions of the gel (and, for some compounds, with other calcium-rich components of the concrete) to form a pink-stained gel. The significance of the pink staining is twofold. First, it can provide a high contrast to the yellow-stained gels, making them easier to observe. Second, some rhodamine compounds react predominantly with Ca-rich ASR gels. Some aspects of staining by rhodamine remain the subject of continued study and may be useful for a more detailed understanding of ASR progression and other deterioration mechanisms. Ho...
Eiliv Steinnes - One of the best experts on this subject based on the ideXlab platform.
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integration of soil magnetometry and geochemistry for assessment of human health risk from metallurgical slag dumps
Environmental Science and Pollution Research, 2017Co-Authors: Marzena Rachwal, Malgorzata Wawer, Tadeusz Magiera, Eiliv SteinnesAbstract:The main objective of the study was an assessment of the pollution level of agricultural land located close to dumps of industrial waste remaining after former Zn and Pb ore processing in Poland. The integrated geophysical-Geochemical Methods were applied for assessment of soil quality with respect to trace element pollution. Additionally, human health risk induced by the contaminated arable soil and dusting slag heap was estimated. The investigations pointed out that soils in the vicinity of the metallurgical slag dump in Piekary were heavily polluted. Spatial distribution of magnetic susceptibility corresponding well with distribution of the content of potentially toxic elements indicated the local "pollution hotspots." Proper geophysical and Geochemical data interpretation supported by statistical factor analysis enabled identification of three different sources of pollution including metallurgical slug dump as a main source, but also traffic pollution influencing the area located along the busy road and relatively strong influence of the Geochemical background. Computed health hazard index revealed no adverse health effect to the farmers cultivating arable soil, but in the direct vicinity of dusting, slag dump health risk occurred, caused mostly by very toxic elements as As and Tl. In the future, investigation should be focused on contribution of different sources to the heavy metal pollution in soil-crop system in this area. It should be highlighted that a site-specific approach should be taken in order to redevelop this kind of area in order to reduce ecological and human health threat. The study proved the integrated two-stage geophysical-Geochemical Method to be a feasible, reliable, and cost-effective tool for identification of the extent of soil pollution and areas at risk.
Garabato, Alberto C. Naveira - One of the best experts on this subject based on the ideXlab platform.
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Arctic freshwater fluxes: sources, tracer budgets and inconsistencies
'Copernicus GmbH', 2020Co-Authors: Forryan Alexander, Bacon Sheldon, Tsubouchi Takamasa, Torres-valdés Sinhué, Garabato, Alberto C. NaveiraAbstract:The net rate of freshwater input to the Arctic Ocean has been calculated in the past by two Methods: directly, as the sum of precipitation, evaporation and runoff, an approach hindered by sparsity of measurements, and by the ice and ocean budget Method, where the net surface freshwater flux within a defined boundary is calculated from the rate of dilution of salinity, comparing ocean inflows with ice and ocean outflows. Here a third Method is introduced, the Geochemical Method, as a modification of the budget Method. A standard approach uses Geochemical tracers (salinity, oxygen isotopes, inorganic nutrients) to compute “source fractions” that quantify a water parcel's constituent proportions of seawater, freshwater of meteoric origin, and either sea ice melt or brine (from the freezing-out of sea ice). The Geochemical Method combines the source fractions with the boundary velocity field of the budget Method to quantify the net flux derived from each source. Here it is shown that the Geochemical Method generates an Arctic Ocean surface freshwater flux, which is also the meteoric source flux, of 200±44 mSv (1 Sv=106 m3 s−1), statistically indistinguishable from the budget Method's 187±44 mSv, so that two different approaches to surface freshwater flux calculation are reconciled. The freshwater export rate of sea ice (40±14 mSv) is similar to the brine export flux, due to the “freshwater deficit” left by the freezing-out of sea ice (60±50 mSv). Inorganic nutrients are used to define Atlantic and Pacific seawater categories, and the results show significant non-conservation, whereby Atlantic seawater is effectively “converted” into Pacific seawater. This is hypothesized to be a consequence of denitrification within the Arctic Ocean, a process likely becoming more important with seasonal sea ice retreat. While inorganic nutrients may now be delivering ambiguous results on seawater origins, they may prove useful to quantify the Arctic Ocean's net denitrification rate. End point degeneracy is also discussed: multiple property definitions that lie along the same “mixing line” generate confused results.publishedVersio