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Bioresource and Agricultural Engineering Commons™
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Full-Text Articles in Bioresource and Agricultural Engineering
Adsorption-Dissolution Reactions Affecting The Distribution And Stability Of Coii Edta In Iron Oxide-Coated Sand, James E. Szecsody, John M. Zachara, Patrick Bruckhart
Adsorption-Dissolution Reactions Affecting The Distribution And Stability Of Coii Edta In Iron Oxide-Coated Sand, James E. Szecsody, John M. Zachara, Patrick Bruckhart
US Department of Energy Publications
The time-variant chemical behavior of CoIIEDTA (and other metal-EDTA complexes) was investigated in suspensions of iron oxide-coated sand to identify equilibrium and kinetic reactions that control the mobility of MeIIEDTA complexes in subsurface environments. Batch experiments were conducted to evaluate the adsorption as a function of pH, concentration, and time and to quantify the rate-controlling step(s) of dissolution of the iron oxide by EDTA complexes. Ionic Co2+ exhibited typical cation-like adsorption, whereas MeIIEDTA adsorption was ligand-like, increasing with decreasing pH. Adsorption isotherms for all reactive species exhibited Langmuir behavior, with site saturation occurring …
Interaction Of Hydrophobic Organic Compounds With Mineral-Bound Humic Substances, Ellyn M. Murphy, John M. Zachara, Steven Smith, Jerry Phillips, Thomas Wletsma
Interaction Of Hydrophobic Organic Compounds With Mineral-Bound Humic Substances, Ellyn M. Murphy, John M. Zachara, Steven Smith, Jerry Phillips, Thomas Wletsma
US Department of Energy Publications
The sorption of hydrophobic organic compounds (HOC) on mineral-associated peat humic acid (PHA) was evaluated under different pH and electrolyte regimes. Relative size distribution measurements indicated that PHA was “coiled” in solution at high ionic strength (I) and elongated at low I. The sorption of PHA to hematite and kaolinite varied with I and electrolyte cation, suggesting that the configuration of the humic acid in solution influenced its structure on the mineral surface. The sorption maxima for PHA on kaolinite indicated that PHA occupies twice the mineral surface area at low I (0.005) as that observed at …
Light, Chlorophyll, Carboxylase Activity And Co2 Fixation At Various Depths In The Chlorenchyma Of Opuntia Ficus-Indica (L.) Miller Under Current And Elevated Co2, Park S. Nobel, Muyi Cui, Alvaro A. Israel
Light, Chlorophyll, Carboxylase Activity And Co2 Fixation At Various Depths In The Chlorenchyma Of Opuntia Ficus-Indica (L.) Miller Under Current And Elevated Co2, Park S. Nobel, Muyi Cui, Alvaro A. Israel
US Department of Energy Publications
Mature cladodes of Opuntia ficus-indica (L.) Miller have a thick chlorenchyma (about 4 mm) with a relatively high chlorophyll content (0-65 g m-2), suggesting that light may be greatly attenuated and hence CO2 fixation negligible in the inner part of this tissue. Indeed, blue light (400-470 nm) and red light (670-685 nm) were 99% attenuated in the outer 2 mm of the chlorenchyma when the cladodes developed under both current and elevated CO2 concentrations. Nevertheless, the nocturnal acidity increase and 14C accumulation following a brief exposure to 14CO2 at night decreased only 22 …