Soil metals, complexed

In situ densitometry has been the most preferred method for quantitative analysis of substances. The important applications of densitometry in inorganic PLC include the determination of boron in water and soil samples [38], N03 and FefCNfg in molasses [56], Se in food and biological samples [28,30], rare earths in lanthanum, glass, and monazite sand [22], Mg in aluminum alloys [57], metallic complexes in ground water and electroplating waste water [58], and the bromate ion in bread [59]. TLC in combination with in situ fluorometry has been used for the isolation and determination of zirconium in bauxite and almnimun alloys [34]. The chromatographic system was silica gel as the stationary phase and butanol + methanol + HCl -H water -n HF (30 15 30 10 7) as the mobile phase. 

In addition, dissolved organic carbon (DOC) is also an important soil solution solute affecting speciation and bioavailability of many trace elements in soil solution. Many trace elements and heavy metals complex with dissolved organic carbon. This is especially important in arid and semi-arid environments since high soil pH increases the solubility of organic molecules and accordingly increases concentrations of dissolved organic carbon in soil solution. 

Stevenson F.J. Nature of divalent transition metal complexes of humic acids as revealed by a modified potentiometric titration method. Soil Sci 1977 123 10-17. 

Humus and organic matter can have a dramatic effect on analytical results as shown in the work by Gerke [16]. Metal complexes, particularly aluminum and iron, were found to complex with phosphate. These complexes, which accounted for 50-80% of the phosphate present, were not detectable by standard phosphate analytical procedures. When developing a soil analytical method, it is essential that the method be either applicable to soils of all organic matter contents or that variations of the procedure applicable to soils of differing organic matter be developed [16-19],... 

Metal complexation (and fixation) in soils and sedimentary basins Deposition of ore metals (reducing agents)... 

Phosphate is widely used as a chemical stabilization agent for MSW combustion residues in Japan and North America and is under consideration for use in parts of Europe. The application of this technology to MSW ashes generally parallels its application to contaminated soils. Metal phosphates (notably Cd, Cu, Pb and Zn) frequently have wide pH distribution, pH-pE predominance, and redox stability within complex ash pore water systems. Stabilization mechanisms identified in other contaminated systems (e.g., soils), involving a combination of sorption, heterogeneous nucleation, and surface precipitation, or solution-phase precipitation are generally observed in ash systems. 

Due to the various health risks of different element species, there are a multitude of applications for natural water samples in this field (e.g., Cr and Sb speciation or Br and I determination).19 The investigation of heavy metal complexes with humic substances by isotope dilution SEC-ICP-MS has been described, for example, by McSheehy and Mester.20 Copper, zinc and molybdenum were found to form complexes with similar size fractions of humic substances in seepage water samples from soils. Sturgeon s group proposed the use of solid phase microextraction (SPME)... 

The presence of soil complicates metal removal because soils sorb metals strongly and can also affect microbial—metal complexation. Walkeretal. (1989) showed that purified preparations of cell walls from Bacillus subtilis and Escherichia coli (423 to 973 mmol metal/g cell wall) were more effective than either of two clays, kaolinite (0.46 to 37 mmol metal/g clay), or smectite (1 to 197 nmol metal/g clay), in the binding of seven different metals. However, in the presence of cell-wall/clay mixtures, binding was reduced. In summary, there are several parameters that affect metal complexation. These include specific surface properties of the organism, cell metabolism, metal type, and the physicochemical parameters of the environment. 

Dyes. In dyeing PES-wool mixtures, disperse dyes are used for the PES component, and acid or metal-complex dyes for the wool. Disperse dyes can soil wool to a great extent. Since they produce poorly fast dyeings on wool, the dyes selected must stain wool as slightly as possible or must be easily removable by a washing step, which may be reductive if necessary. Frequently used dyes are C.I. Disperse Yellow 23, 54, 64 C.I. Disperse Orange 30, 33 C.I. Disperse Red 50, 60, 73, 91, 167, 179 and C.I. DisperseBlue 56, 73, 87. Premixed dyes consisting of disperse and wool dyes are occasionally available. 

Sposito, G., Holtzclaw, K. M., and Baham, J. (1976). Analytical properties of the soluble, metal-complexing fractions in sludge-soil mixtures II. Comparative structural chemistry of fulvic acid. Soil Sci. Soc. Am. J. 40, 691-697. 

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