Preliminary evaluation of a national wildlife and fish data base
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Transactions of the North American Wildlife and Na↗
Geology topics
R.B. Barnes
Publications and source records attributed to R.B. Barnes.
Stability of fluoride complex with silica and its distribution in natural water systems
Fluoride reacts with silicic acid to form SiF 2− 6 . A fluoride electrode was used to obtain an equilibrium constant of 10 30.18 for the reaction: Si(OH) 0 6 + 6 F − +4 H + = SiF 2− 6 + 4 H 2 O "> Si(OH)06+ 6F−+4H+=SiF2−6+ 4H2O at 25°C Although there may be some experimental evidence for existence of traces of species containing less than six F − ions per silicon ( n = 6), the species SiF 2− 6 predominates for n values from about 0.1 to 6. Silicic-acid complexing with fluoride is important only in solutions which have rather low pH and low concentrations of other cations which compete with silicon for fluoride. Computations for cold volcanic condensates from Hawaii indicate that for some samples much of the silicon is complexed by fluoride as SiF 2− 6 . However, in most cooled acidic natural water samples Al and Fe are more important than Si in complexing fluoride.
Chemical Geology↗
The determination of specific forms of aluminum in natural water
A procedure for analysis and pretreatment of natural-water samples to determine very low concentrations of Al is described which distinguishes the rapidly reacting equilibrium species from the metastable or slowly reacting macro ions and colloidal suspended material. Aluminum is complexed with 8-hydroxyquinoline (oxine), pH is adjusted to 8.3 to minimize interferences, and the aluminum oxinate is extracted with methyl isobutyl ketone (MIBK) prior to analysis by atomic absorption. To determine equilibrium species only, the contact time between sample and 8-hydroxyquinoline is minimized. The Al may be extracted at the sample site with a minimum of equipment and the MIBK extract stored for several weeks prior to atomic absorption analysis. Data obtained from analyses of 39 natural groundwater samples indicate that filtration through a 0.1-μm pore size filter is not an adequate means of removing all insoluble and metastable Al species present, and extraction of Al immediately after collection is necessary if only dissolved and readily reactive species are to be determined. An average of 63% of the Al present in natural waters that had been filtered through 0.1-μm pore size filters was in the form of monomeric ions. The total Al concentration, which includes all forms that passed through a 0.1-μm pore size filter, ranged 2–70 μg/l. The concentration of Al in the form of monomeric ions ranged from below detection to 57 μg/l. Most of the natural water samples used in this study were collected from thermal springs and oil wells.
Chemical Geology↗