Aquatic Carbonate Systems: Chemical Processes in Natural Waters and Global Cycles

1994 ◽  
pp. 47-71 ◽  
Author(s):  
R. Wollast ◽  
J. P. Vanderborght
Keyword(s):  
Natural Waters ◽  
Chemical Processes ◽  
Global Cycles

Electrochemical and chemical processes for hydride generation in flow injection ICP-MS: determination of arsenic in natural waters

1998 ◽  
Vol 13 (12) ◽  
pp. 1343-1346 ◽  
Author(s):  
Luis Fernando R. Machado ◽  
Antonio Octávio vio Jacintho ◽  
Amauri A. Menegário ◽  
Elias A. G. Zagatto ◽  
Maria Fernanda Giné
Keyword(s):  
Flow Injection ◽  
Natural Waters ◽  
Hydride Generation ◽  
Chemical Processes ◽  
Icp Ms

Phosphate mineral reactivity: from global cycles to sustainable development

2008 ◽  
Vol 72 (1) ◽  
pp. 337-340 ◽  
Author(s):  
E. H. Oelkers ◽  
E. Valsami-Jones ◽  
T. Roncal-Herrero
Keyword(s):  
Surface Area ◽  
Natural Waters ◽  
High Surface ◽  
High Surface Area ◽  
Relative Strength ◽  
Phosphorus Cycle ◽  
Phosphate Mineral ◽  
Mineral Structure ◽  
Global Cycles ◽  
Mineral Reactivity

AbstractA survey of the surface-area-normalized dissolution rates of major phosphate bearing minerals shows these rates to vary by >8 orders of magnitude with a general dissolution-rate trend sturvite > britholite ∼ fluoroapatite > variscite > monazite ∼ rhabdophane. This trend reflects the relative strength of the metal-oxygen bonds holding together the phosphate tetrahedra in the mineral structure. Due to the high surface-area-normalized reactivity of fluoroapatite, and the high surface area of natural variscite and rhabdophane, it seems likely that these minerals buffer the concentration of P and the rare-earth elements in many natural waters. As such, the solubility of these minerals plays a significant role in the global phosphorus cycle, and may potentially provide clues for future sustainable phosphorus use.

Electrical Damage Due to Low Energy Plasma Processing of GaAs Structures

1991 ◽  
Vol 223 ◽  
Author(s):  
Hans P. Zappe ◽  
Gudrun Kaufel
Keyword(s):  
Chemical Processes ◽  
Low Energy ◽  
Electrical Behavior ◽  
Rapid Thermal Anneal ◽  
High Temperature Anneal ◽  
Significant Damage ◽  
Low Energies ◽  
Long Time ◽  
Physical Plasma

ABSTRACTThe effect of numerous plasma reative ion etch and physical milling processes on the electrical behavior of GaAs bulk substrates has been investigated by means of electric microwave absorption. It was seen that plasma treatments at quite low energies may significantly affect the electrical quality of the etched semiconductor. Predominantly physical plasma etchants (Ar) were seen to create significant damage at very low energies. Chemical processes (involving Cl or F), while somewhat less pernicious, also gave rise to electrical substrate damage, the effect greater for hydrogenic ambients. Whereas rapid thermal anneal treatments tend to worsen the electrical integrity, some substrates respond positively to long-time high temperature anneal steps.

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