...M. P. Hegde; U. Aswathanarayana Abstract Sixteen samples of metavolcanics of Ingaldhal have been analysed for sulphur and for Cu, Co, Ni and Zn (in the hydrogen peroxide-ascorbic acid leach solution). There is no visible mineralisation where the S content in the metavolcanics is below 200 ppm...

... transition, which is driven by the intrinsic electric forces of siderite crystallites. Addition of the biomolecule ascorbic acid not only prevents Fe 2+ oxidation in the alkaline solution environment but also modifies the growth of siderite. Moreover, with increasing Fe 2+ concentrations, siderite...

... experiments of the hematite nanocrystals in ascorbic acid solution, in which we demonstrated that the nanopores are reactive sites for dissolution and enlarged by preferential etching. Our findings are of fundamental importance to understanding how certain crystal morphologies, internal structures, defects...

... in distilled water, 570 ml of freshly opened concentrated aqueous ammonia added and diluted to 1000 ml with water. (i) Formaldehyde: 40% aqueous solution. (j) Nitric acid (2 N). (k) Liquid Bromine. (I) Triethanolamine. (m) Solid reagents A. R. Quality. (I) Ammonium thiocyanate. (2) Ascorbic acid. (3) Potassium...

... sulfuric, oxalic and ascorbic acid, and ammonium molybdate were added to the analysed solution in proportions prescribed by Tréguer and Le Corre ( 1975 ) ( Table 2 ). The ammonium molybdate solution was first mixed at a flow rate of 0.8 ml/min with the sample at a flow rate of 0.32 ml/min. Thereafter...

... ) have estimated the iceberg input of nanoparticulate Fe to the Southern Ocean derived from sediments to be 1250 Gg yr −1 . This was based on melting 2500 km 3 yr −1 of ice containing 0.5 kg m −3 of sediment with an ascorbic acid-extractable Fe content of 0.1%. The models in Section 6.4 use a lower...

... is used below to quantify the potential delivery rate of bioavailable Fe solely from the iron extractable by ascorbic acid. This Fe (see Raiswell et al ., 2010 ) is assumed to be present in dust that has been atmospherically processed as nanoparticulate ferrihydrite (in dry deposition) accompanied...

... citrate, 50 g l −1 sodium bicarbonate and 10 g l −1 of ascorbic acid. Approximately 30 mg of sample were mixed with 10 ml of the ascorbate solution, shaken for 24 h at room temperature and filtered through a 0.45 μm membrane filter. The Fe removed by ascorbate is hereafter termed FeA, and was measured...

...F igure 4 Variation over time in the rate constant for the dissolution of ferrihydrite in ascorbic acid with or without storage and filtering (plus drying). The red curve shows rate constant changes for a ferrihydrite suspension with time. The arrows to the brown curve show the decrease...

... hydrous oxides of Fe and Al. The As associated with well crystallized hydrous oxides of Fe and Al was then targeted by exposing the residue to 25 ml of 0.2 M NH 4 -oxalate buffer (pH 3.0) and 0.1 M ascorbic acid and incubating the suspension at 90°C in a water bath for 30 min in the light with occasional...

... Al and organic matter-associated 4 NH 4 -oxalate 0.2 m pH 3.25 − 4 h shaking in the dark Bound to amorphous oxides 5 NH 4 -oxalate 0.2 m + ascorbic acid 0.1 m − pH 3.25. 30 min shaking in water bath at 96°C Bound to crystalline oxides After the period of extraction...

...Figure SI-4 Variation in ferrihydrite reactivity with time and sample treatment, as shown by changes in the rate constant for dissolution in ascorbic acid (from Raiswell, 2011a , with permission from Elements). ...

... and target Fe and Al mineral phases. Extractant Target mineral phase Reference Ascorbic acid Amorphous iron oxide/hydroxide Kostka and Luther (1994) ISO (2012a) Hydroxylamine–hydrochloric acid (NH 2 OH–HCl) Amorphous iron oxide/hydroxide Chao and Zhou (1983) Kostka and Luther (1994...

... that the lichen Xanthoria has gonidia which cannot perform photosynthesis without a diënol. This alga is therefore (1) or (2). The fungus needs aneurine, is therefore (4). They are therefore as follows (roman numerals mean “capable”, arabic numerals is “incapable”): Ascorbic acid C 6 H 6 O 8 , are all...