Iron humate

From the geochemical data it follows that a substantial part of dissolved iron migrates not in ionic form, but as Fe(OH)3 sol shielded by organic matter (also colloidal) or by a sol of SiO, and also as colloidal (or truly dissolved) complex ferro-organic compounds, chiefly soluble iron humates (Strakhov, 1960). 

Kovalev, V.A. and Generalova, V.A., 1974. Modeling of sulphide formation from iron humate complexes (in Russian). Geokhimiya, 3 425—533. 

Lakatos, B., Koreca, L., and Meisel, J. (1977a). Comparative study of Mossbauer parameters of iron humates and polyuronates. Geoderma 19, 149-157. 

Janos P. Sorption of basic dyes onto iron humate. Environ Sci Technol 2003 37 5792-... 

Janos P, Smidova V. Effects of surfactants on the adsorptive removal of basic dyes from water using an organomineral sorbent - iron humate. J Colloid Interface Sci 2005 291 19-27. 

J. C. Lobartini and G. A. Orioli, Adsorption of iron Fe-humate in nutrient. solution by plants. Plant Soil 706 153 (1988). 

Sinha (60,61) has suggested that humic and fulvic acids play a major role in mobilising iron and transporting it from the soil to plant roots. At the normal soil pH it is believed that iron bound by the fulvic acid is partially hydroxylated as Fe(OH)2 (62). These complexes interact with phosphate to give an organicmetallic phosphate which may be taken up by plants (60). It has been suggested that the entire humic-iron-phosphate complex is taken up by the roots of plants and not just the iron and phosphate (60, 63). Jorgensen (64) has observed that soil humates suppress the uptake of Pb2+ into plants it is possible that they will also suppress actinide concentration in plants. 

Although the soil humates may be agents in the concentration of iron and facilitate iron uptake into plants it is by no means certain that the humates are bringing about the concentration of other metals in plants. 

Eckert, J.M., and Sholkovitz, E.R. (1976) The flocculation of iron, aluminum and humates from river water by electrolytes. Geochim. Cosmochim. Acta 40, 847-848. 

Levashkevich (1968) experimentally studied the ability of specific humic acids in several types of soils to form chelated compounds with ionic forms of iron (Fe " "). It was established that in the reactions of chelate formation Fe203 is bound with humic acids into compounds in which the iron loses the properties of an independent ion, and fulvic acids have higher complexforming capability than humic. The maximum amount of Fe that can be bound with fulvic acids reaches 650-711 mg per 1 g of organic matter, with humic acids, 119-152 mg. Chelated compounds of FcjOj with fulvic acids are considerably mobile, but solution of humate complexes occurs only in alkaline environments (at pH = V.3-7.7). In acid environments these com-... 

The MPF and TMGM prospecting methods are based on the use of metallo-organics (fulvates and humates of metals) and oxides of iron and manganese (metals bound in oxides and hydroxides of iron and manganese). These forms of metals are the result of the secondary fixation of the movable fomis in rocks and have features such as (1) increased concentration coefficient and (2) only a weak bond with their initial geological source (in comparison, for example, with the movable forms collected in CHIM and MDE). Samples for MPF are taken from the humus-enriched layer at a depth of 5-10 cm, and samples for TMGM are taken from the sand-clay layer at a depth of 15-20 cm. 

Of the other forms of nonresidual associations, some metal-organic compounds, for example, fulvic and humic acids, have been shown to be particularly effective in the transfer of (toxic) metals from inorganic matter into organisms 51). According to Table II, where data of humate extractions with O.IN NaOH are compared, these effects should be more relevant for iron, copper, zinc, and lead in the sample from the Rhine River than in the sediment material from Lake Constance. The other nonresidual metal associations (easily reducible, carbonates, moderately reducible forms) partly indicate higher percentages in Lake Constance sediments (Mn and Pb), whereas others (chromium, copper, and zinc) are enriched in the Rhine sample. 

In the O.IN NaOH extractable fraction (which is assumed to reflect the humic acid phases) of the Rhine sediment, PCF values are particularly high for iron, copper, and lead, exhibiting a slight increase in the fine-grained particles compared with the silt-sized material. For the sample from Lake Constance, the concentration factors in the humate phase have been found to be 11 and 40 for copper, 9 and 12 for iron, and 5 and 9 for chromium, in the pelitic and silty sediment fractions, respectively. Similar concentration factors of trace metals in the NaOH-extractable matter have been observed by Chen et al. (14) for chromium, lead, copper, and zinc, whereas iron and manganese showed no significant association with this fraction. 

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