Oxalic acid geochemistry

Procedures for pretreatment of soil samples and synthesis of sample benzene for 14C analysis had been described in Chen et al. (2002b). Sample benzene was often left for 3-4 weeks to allow any radon with half-life of 3.82 days that may be present to decay. 14C activity of the CgFL was then determined using a 1220-QUANTULUS ultralow-level liquid scintillation spectrometer manufactured by WALLAC Company, Sweden. The 14C analyses were conducted at the Guangzhou Institute of Geochemistry, CAS. Results are reported as A14C, in parts per thousand of the 14C/12C ratio from that of the standard (oxalic acid decay corrected to 1950) (Stuiver and Po-lach 1977), and corrected for bomb 14C (Chen et al. 2002b), where ... 

In the fields of environmental and exploration geochemistry, considerable use has been made of sequential extraction procedures in order to determine the bioavailability and geomobUity of trace metals (including V, Cr, As, Se, Cd and Pb). More recently, sequential extractions have been used to elucidate information relating to the speciation of metals in soils and sediments. The extraction protocol developed by Tessier " has traditionally been used (with modifications) and involves the sequential use of a variable cocktail of extractants including acetic acid, sodium acetate, magnesiumchloride, EDTA, acidified hydroxylamine hydrochloride, oxalic acid, sodium... 

Kettler RM, Palmer DA, Wesolowski DJ (1991) Dissociation quotients of oxalic acid in aqueous sodium chloride media to 175 °C. J Solution Chem 20 905-927 Kettler RM, Wesolowski DJ, Palmer DA (1992) Dissociation quotients of malonic acid in aqueous sodium chloride media to 100 °C. J Solution Chem 21 883-900 Kharaka YK, Lico MS, Wright VA, Carothers WW (1979) Geochemistry of formation waters from Pleasant Bayou No. 2 well and adjacent areas in coastal Texas. Proc 4th US Gulf Coast Geopressured-Geothermal Energy Conf, Research and Development, University of Texas at Austin, pp 168-199... 

Tait CD, Janecky DR, Clark DL, Bennett PC (1991) Oxalate complexation with aluminum(III) and iron(III) at moderately elevated temperatures. In Kharaka Y K, Maest A S (eds) Water-rock interaction. Balkema, Rotterdam, pp 349-353 Tan KH (1980) The release of silicon, aluminum, and potassium during decomposition of soil minerals by humic acid. Soil Sci 129 5-11 Tandura SN, Voronkov MG, Alekseev NV (1986) Molecular and electronic structure of penta- and hexacoordinate silicon compounds. Top Curr Chem 131 99-189 Thurman EM (1979) Organic geochemistry of natural waters. Nijhoff, Dordrecht, 497 pp Webley DM, Henderson MEF, Taylor EF (1963) The microbiology of rocks and weathered stones. J Soil Sci 14 102-112... 

Much work has been published on the dissolution of iron oxides in connection with the iron cycle in geochemistry, decontamination processes or the clean-up of industrial facilities. We have already seen that strong chelating agents such as EDTA or amino acids can adsorb on the surface of oxides and promote their dissolution because they can form anion complexes that are more stable than the oxide [52,63,64], Citrates and oxalates, among others, act in a similar way [65], Dissolution of oxides is markedly accelerated if oxidation-reduction processes occur in conjunction with anion adsorption [66]. The adsorption of ascorbate on hematite is a good example [67] (Figure 9.16). The reduction of ferric ions is shown... 

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