Radiotracer studies, colloidal

In natural systems microbiological oxidation may offer a faster pathway, particularly at pH < 8 and low concentrations (<5 jlM) of particulate oxides. Hastings and Emerson (17) showed that sporulated cultures of marine bacillus SG-1 at pH 7.5 accelerated the oxidation of Mn(II) by a factor of 104 with respect to the abiotic catalysis on a colloidal MnOz surface. A radiotracer study of microbial Mn oxidation in a marine fjord revealed half-lives as short as 2 days (18). Perhaps microorganisms can use the entire redox cycle of manganese. A study indicates that the vegetative cells of spores that mediate Mn(II) oxidation also reduce manganese oxides (19). 

A, and fibronectin in the submonolayer region evaluated by a combined study of ellipsometry and radiotracer techniques,. Colloid. Interface Set, 103 (1985) 360-372. 

In a study of the bioaccumulation of metals as colloid complexes and free ions by the marine brown shrimp, Penaeus aztecus [29] the colloids were isolated and concentrated from water obtained from Dickinson Bayou, an inlet of Galveston Bay, Texas, using various filtration and ultrafiltration systems equipped with a spiral-wound 1 kDa cutoff cartridge. The total colloidal organic carbon in the concentrate was found to be 78 lmgdm 3. The shrimps were exposed to metals (Mn, Fe, Co, Zn, Cd, Ag, Sn, Ba and Hg) as radiolabelled colloid complexes, and free-ionic radiotracers using ultrafiltered seawater without radiotracers as controls. The experiments were designed so that the animals were exposed to environmentally realistic metal and colloid concentrations. 

Horanyi, G. and Joo, R, Application of the radiotracer technique for the study of the specific anion adsorption on AI2O, in acidic medium, J. Colloid Interf. Sci., 231, 373, 2000. 

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