Sulfur, transport

F. Bourgis, S. Roje, M. L. Nuccio, D. B. Fisher, M. C. Tarczynski, C. Li, C. Herschbach, H. Rennenberg, M. J. Pimenta, T. L. Shen, D. A. Gage, A. D. Hanson, 5-methylmethionine plays a major role in phloem sulfur transport and is synthesized by a novel type of methyltransferase, Plant Cell., 11 (1999), 1485D1498. 

As a simple example of a multiple layer process we shall consider an arrangement A(metal)/AF/AB2/B2(gas), suchasis realized for example in the action of sulfur vapor on iron within certain ranges of pressure and temperature (Fig. 5). If the sulfur transport is assumed to be negligibly small, i. e., Sg 0 in both phases, then there can be no AB formation at the phase boundary A/AB, whereas at the gas boundary the AB2 lattice structure is completely determined by s 2 The formation of AB independently of the migration mechanism of the A particles involves only the A particles which do not migrate any further because of the reaction ... 

Kaplan, I.R. and Rittenberg, S.C., 1962. Fractionation of isotopes in relation to the problem of elemental sulfur transport by microorganisms. Nature, 194 1098—1099. 

Reducing Dependence on Imported Oil Zero Sulfur Transportation Fuels from Domestic Coal, Gray, D., Tomlinson, G., Mitretek Systems, NCEP Forum The Future of Biomass and Transportation Fuels, June, 2003. 

A number of problems connected with battery construction and operation, such as rechargeability into the two-phase region which requires improvement of sulfur transport away from the solid electrolyte and carbon surface,and development of sealing techniques and of ceramic mass production, have been to a great extent overcome. The remaining difficulties are primarily connected with the reliability and cycle life of the battery. 

Fig. 4.1. A summary of natural circulation of sulfur. As the intake of hydrogen sulfide by plants is limited to non-photosynthetic plants (fungi, bacteria, etc.), the arrow indicating the sulfur transport from hydrogen sulfide to plants is shown by a dotted line...

More complicated models of sulfur transport and deposition differ in details but typically use the same chemical reactions and mechanisms as shown above. 

Finally, Winther et al. (1998) studied diffusion of sulfur in dry albitic melt at 1300-1500°C and 1 GPa. They found that in this highly polymerized melt, sulfate ions are unusually stable, even at low fo. However, these are relatively immobile, and rapid speciation reaction takes place in this case, to form some S2 and S3 ions. The sulfate ions are still less mobile than sulfides but are nevertheless the dominant sulfur transport species in albite melt. The resulting transport rates, given by Dsui r = 1.47 x 10 (cm /sec) exp(-458,100/RT) are significantly slower than the other rates reported above, where diffusion is presumably controlled by motion of sulfides. As expected, these diffusivities are closest to the rates for dry rhyolite and obsidian obtained by Baker and Rutherford... 

It is well documented that, selenate is taken up by plant roots from soil solution by a process of active transport (Brown and Shrift 1982). It competes with sulfur for uptake, both anions using a sulfate transporter in the root plasma membrane (Arvy 1993). Organic forms of Se, such as selenomethionine, are also taken up actively by plant roots. In contrast, transport of selenite does not appear to require the use of a sulfur transporter (Abrams et al. 1990). Subsequent translocation of Se within the plant is related to the form in which the element is supplied to the root. Se04 is more easily transported from the roots and much more is accumulated in the leaves than either SeOs" or organic selenium. Much of the SeOs is retained in the roots where it is rapidly converted into organic forms, particularly selenomethionine (Zayed et al. 1998). Distribution of Se in various tissues differs between accumulator and nonaccumulator plants. In the former, the Se is accumulated especially in young leaves, but later appears at higher levels in seeds than in other tissues, while, in nonaccumulators, such as cereals, levels in seeds and roots are usually the same as reviewed by Reilly (2(X)6). 

Amount of sulfur carried outside the eastern U. S. The amount of sulfur carried by wind to Canada can be estimated knowing the average level of sulfur in the air, and the average northerly wind speed. It is determined to be 6.0 million toimes of sulfur (calculated as sulfate) per year, about two to three times more than the amount of sulfur transported from Canada to the U.S. The amount of sulfur carried over the Atlantic is determined in the same way, using the average westerly component of the wind, and is estimated to be 11.7 million tonnes per year. (An independent estimate can be made using rainfall data from over the Atlantic, and is consistent with the above estimate.) ... 

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