The Experts below are selected from a list of 19656 Experts worldwide ranked by ideXlab platform
Nihat Hakan Akyol - One of the best experts on this subject based on the ideXlab platform.
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adsorption and transport of arsenate in Carbonate rich Soils coupled effects of nonlinear and rate limited sorption
Chemosphere, 2008Co-Authors: Irfan Yolcubal, Nihat Hakan AkyolAbstract:Abstract The transport and fate of arsenate in Carbonate-rich Soil under alkaline conditions was investigated with multiple approaches combining batch, sequential extraction and column experiments as well as transport modeling studies. Batch experiments indicated that sorption isotherm was nonlinear over a wide range of concentration (0.1–200 mg L−1) examined. As(V) adsorption to the calcareous Soil was initially fast but then continued at a slower rate, indicating the potential effect of rate-limited sorption on transport. Column experiments illustrated that transport of As(V) was significantly retarded compared to a non-reactive tracer. The degree of retardation decreased with increasing As(V) concentration. As(V) breakthrough curves exhibited nonideal transport behavior due to the coupled effects of nonlinear and rate-limited sorption on arsenate transport, which is consistent with the results of modeling studies. The contribution of nonlinear sorption to the arsenate retardation was negligible at low concentration but increased with increasing As(V) concentration. Sequential extraction results showed that nonspecifically sorbed (easily exchangeable, outer sphere complexes) fraction of arsenate is dominant with respect to the inner-sphere surface bound complexes of arsenate in the Carbonate Soil fraction, indicating high bioavailability and transport for arsenate in the Carbonate-rich Soils of which Fe and Al oxyhydroxide fractions are limited.
A C Stoker - One of the best experts on this subject based on the ideXlab platform.
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the effect of Carbonate Soil on transport and dose estimates for long lived radionuclides at a u s pacific test site
7th International Conference on Low Level Measurements of Actinides and Long-Lived Radionuclides in Biological and Environmental Samples Salt Lake Cit, 1999Co-Authors: C L Conrado, T F Hamilton, W L Robison, A C StokerAbstract:The US conducted a series of nuclear tests from 1946 to 1958 at Bikini, a coral atoll, in the Marshall Islands (MI). The aquatic and terrestrial environments of the atoll are still contaminated with several long-lived radionuclides that were generated during testing. The four major radionuclides found in terrestrial plants and Soils are Cesium-137 ({sup 137}Cs), Strontium-90 ({sup 90}Sr), Plutonium-239+240 ({sup 239+240}Pu) and Americium-241 ({sup 241}Am). {sup 137}Cs in the coral Soils is more available for uptake by plants than {sup 137}Cs associated with continental Soils of North America or Europe. Soil-to-plant {sup 137}Cs median concentration ratios (CR) (kBq kg{sup {minus}1} dry weight plant/kBq kg{sup {minus}1} dry weight Soil) for tropical fruits and vegetables range between 0.8 and 36, much larger than the range of 0.005 to 0.5 reported for vegetation in temperate zones. Conversely, {sup 90}Sr median CRs range from 0.006 to 1.0 at the atoll versus a range from 0.02 to 3.0 for continental silica-based Soils. Thus, the relative uptake of {sup 137}Cs and {sup 90}Sr by plants in Carbonate Soils is reversed from that observed in silica-based Soils. The CRs for {sup 239+240}Pu and {sup 241}Am are very similar to those observed in continental Soils. Values range from 10{sup {minus}6} to 10{sup {minus}4} for both {sup 239+240}Pu and {sup 241}Am. No significant difference is observed between the two in coral Soil.
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the effect of Carbonate Soil on transport and dose estimates for long lived radionuclides at a u s pacific test site
Journal of Radioanalytical and Nuclear Chemistry, 1998Co-Authors: C L Conrado, T F Hamilton, W L Robison, A C StokerAbstract:The United States conducted a series of nuclear tests from 1946 to 1958 at Bikini, a coral atoll, in the Marshall Islands (MI). The aquatic and terrestrial environments of the atoll are still contaminated with several long-lived radionuclides that were generated during testing. The four major radionuclides found in terrestrial plants and Soils are Cesium-137 ({sup 137} Cs), Strontium-90 ({sup 90} Sr), Plutonium-239+ 240 ({sup 239+240}Pu) and Americium-241 ({sup 241}Am). {sup 137}Cs in the coral Soils is more available for uptake by plants than {sup 137}Cs associated with continental Soils of North America or Europe. Soil-to-plant {sup 137}Cs median concentration ratios (CR) (kBq kg{sup {minus}1} dry weight plant/kBq kg {sup {minus}1} dry weight Soil) for tropical fruits and vegetables range between 0.8 and 36, much larger than the range of 0.005 to 0.5 reported for vegetation in temperate zones. Conversely, {sup 90}Sr median CRs range from 0.006 to 1.0 at the atoll versus a range from 0.02 to 3.0 for continental silica-based Soils. Thus, the relative uptake of {sup 137}Cs and {sup 90}Sr by plants in Carbonate Soils is reversed from that observed in silica-based Soils. The CRs for {sup 239+240}Pu and {sup 241}Am are very similar to those observed in continental Soils. Values range from 10{sup {minus}6} to 10{sup {minus}4} for both {sup 239+240}Pu and {sup 241}Am. No significant difference is observed between the two in coral Soil. The uptake of {sup 137}Cs by plants is enhanced because of the absence of mineral binding sites and the low concentration of potassium in the coral Soil. {sup 137}Cs is bound to the organic fraction of the Soil, whereas {sup 90}Sr, {sup 239+240}Pu and {sup 241}Am are primarily bound to Soil particles. Assessment of plant uptake for {sup 137}Cs and {sup 90}Sr into locally grown food crops was a major contributing factor in (1) reliably predicting the radiological dose for returning residents, and (2) developing a strategy to limit the availability and uptake of {sup 137}Cs into locally g
Francesco Interbartolo - One of the best experts on this subject based on the ideXlab platform.
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subaerial exposure and drowning processes in a Carbonate platform during the mesozoic tethyan rifting the case of the jurassic succession of western sicily central mediterranean
Sedimentary Geology, 2016Co-Authors: Attilio Sulli, Francesco InterbartoloAbstract:Abstract The Liassic Carbonate platform succession outcropping at Monte Maranfusa (central Western Sicily) consists of a shallowing-upward sequence of peritidal Carbonates, with Jurassic to Paleogene pelagic limestone and siliciclastic Tertiary covers above. The cyclic sequences of subtidal wackestones/packstones, intertidal microcrystalline Carbonates with bird's-eye pores, and supratidal bioclastic grainstones are interbedded with dark layers of the following composition: 1) dark-gray, compact, and well-cemented limestone with blackish clasts, interpreted as calcretes (a type of Carbonate Soil) and 2) reddish calcite laminae, deformed by elongated cavities, filled with vadose silt, interpreted as paleokarst. This succession is crossed by almost vertical faults, of the Late Liassic to Miocene, which often coincides with neptunian dykes, filled by several generations of Toarcian–Early Miocene pelagic sediments. Another system of dykes, known as neptunian sills, filled by injected Upper Lias–Dogger pelagic sediments, lies parallel to the stratification. The parallel dykes were caused by the flexure of the platform during the Jurassic and presumably by a planar slip in the Carbonate rocks, whereas neptunian dykes are caused by faulting episodes. Here, we present evidence that the dark layers in the Liassic succession of Monte Maranfusa, previously described by many authors only as parallel dykes, can actually be interpreted as a) neptunian sills, b) pedogenic calcretes, and c) paleospeleothems. Therefore, we found evidence of exposure/flooding intervals in the evolution of the Carbonate platform during the Liassic, linked to different pulses in both the subsidence/tectonic activity and the sea-level oscillations. At the top, Fe–Mn crusts (hardgrounds) seal the Carbonate platform succession, which is in turn overlain by condensed pelagic deposits, confirming its drowning during rifting processes.
Irfan Yolcubal - One of the best experts on this subject based on the ideXlab platform.
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adsorption and transport of arsenate in Carbonate rich Soils coupled effects of nonlinear and rate limited sorption
Chemosphere, 2008Co-Authors: Irfan Yolcubal, Nihat Hakan AkyolAbstract:Abstract The transport and fate of arsenate in Carbonate-rich Soil under alkaline conditions was investigated with multiple approaches combining batch, sequential extraction and column experiments as well as transport modeling studies. Batch experiments indicated that sorption isotherm was nonlinear over a wide range of concentration (0.1–200 mg L−1) examined. As(V) adsorption to the calcareous Soil was initially fast but then continued at a slower rate, indicating the potential effect of rate-limited sorption on transport. Column experiments illustrated that transport of As(V) was significantly retarded compared to a non-reactive tracer. The degree of retardation decreased with increasing As(V) concentration. As(V) breakthrough curves exhibited nonideal transport behavior due to the coupled effects of nonlinear and rate-limited sorption on arsenate transport, which is consistent with the results of modeling studies. The contribution of nonlinear sorption to the arsenate retardation was negligible at low concentration but increased with increasing As(V) concentration. Sequential extraction results showed that nonspecifically sorbed (easily exchangeable, outer sphere complexes) fraction of arsenate is dominant with respect to the inner-sphere surface bound complexes of arsenate in the Carbonate Soil fraction, indicating high bioavailability and transport for arsenate in the Carbonate-rich Soils of which Fe and Al oxyhydroxide fractions are limited.
Stefano Poni - One of the best experts on this subject based on the ideXlab platform.
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effect of calcareous Soil on photosynthesis rate mineral nutrition and source sink ratio of table grape
Journal of Plant Nutrition, 2003Co-Authors: Luigi Bavaresco, Stefano PoniAbstract:Abstract Vitis vinifera L. cv Aurora grafted on S.O.4 (medium lime‐tolerance) rootstock was grown in pot with a high‐Carbonate‐Soil and a low‐Carbonate‐Soil. The aim of the trial was to check Soil effect on some physiological features such as leaf chlorophyll (Chl) concentration and gas exchange, whole‐canopy gas exchange, mineral nutrition, dry matter partitioning, and technological grape parameters. Measurements for whole‐canopy gas exchange were taken using a custom‐built, flow‐through whole‐canopy gas exchange system set up to run continuous, automated, and simultaneous net carbon exchange rate (NCER) readings of four canopies. The most significant findings were: (a) high‐Carbonate‐Soil decreased leaf and whole canopy photosynthesis, grape yield, and total dry matter production; (b) high‐Carbonate‐Soil increased the distribution share of dry matter in the trunk and roots, as compared to the low‐Carbonate‐Soil, and decreased the share of dry matter in the clusters; and (c) lime‐stress conditions affect...
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effect of calcareous Soil on photosynthesis rate mineral nutrition and source sink ratio of table grape
Journal of Plant Nutrition, 2003Co-Authors: Luigi Bavaresco, Stefano PoniAbstract:Abstract Vitis vinifera L. cv Aurora grafted on S.O.4 (medium lime‐tolerance) rootstock was grown in pot with a high‐Carbonate‐Soil and a low‐Carbonate‐Soil. The aim of the trial was to check Soil effect on some physiological features such as leaf chlorophyll (Chl) concentration and gas exchange, whole‐canopy gas exchange, mineral nutrition, dry matter partitioning, and technological grape parameters. Measurements for whole‐canopy gas exchange were taken using a custom‐built, flow‐through whole‐canopy gas exchange system set up to run continuous, automated, and simultaneous net carbon exchange rate (NCER) readings of four canopies. The most significant findings were: (a) high‐Carbonate‐Soil decreased leaf and whole canopy photosynthesis, grape yield, and total dry matter production; (b) high‐Carbonate‐Soil increased the distribution share of dry matter in the trunk and roots, as compared to the low‐Carbonate‐Soil, and decreased the share of dry matter in the clusters; and (c) lime‐stress conditions affect...