Element mobility trace elements

Contents of REE in massive sulfides from the BMC are strongly controlled by the abundance of and REE concentrations in phosphate minerals, specifically apatite, xenotime and monazite. Strong positive Eu anomalies in apatite, account for the anomalous Eu signatures of exhalative sulfides whereas REE in monazite masses are largely reflective of detrital sources and may mask hydrothermal signatures. Limited release of mobile trace elements (LREE and Eu) during green-schist facies metamorphism has partly modified REE profiles for VMS deposits of the BMC. 

Kamber B. S., Ewart A., Collerson K. D., Bruce M. C., and McDonald G. D. (2002) Fluid-mobile trace element constraints on the role of slab melting and imphcations for Archean crustal growth models. Contrib. Mineral Petrol. 144, 38-56. 

Comparison of eleven highly mobile trace elements, particularly Zn, In, Bi, T1 and Cd, in C1-C3 chondrites and similar samples heated artificially indicate that about a dozen were thermally metamorphosed in their parent bodies in open systems. Metamorphic temperatures, 400-900 C, estimated in this way agree with estimates provided by mineralogic-petrologic studies. Contents of these trace elements in E5 and E6 chondrites, whether EH or EL, indicate that these meteorites also experienced open-system thermal metamorphism in their parent(s). 

The concentrations of potentially mobile trace elements in H5 and L6 chondrites of Antarctic and non-Antarctic origin (falls only) reported by Lipschntz (1989) permit the conclusion with 90% or higher confidence that the trace-element concentrations of Antarctic meteorites actually do differ from those of the non-Antarctic falls. However, the cause for this difference is still in doubt. On the one hand, the Antarctic meteorites may have originated from a different set of... 

In the present work it has been shown that on-line coupling of flowthrough fractionation in RCC with ICP-EAS detection enables not only the fast and efficient fractionation of trace elements (TE) in environmental solids to be achieved but allows real-time studies on the leaching process be made. A novel five-step sequential extraction scheme was tested in on-line mode. The optimal conditions for the fractionation were chosen. Investigating elution curves provides important information on the efficiency of the reagents used, the leaching time needed for the separation of each fraction, and the potential mobility of HM forms. 

Dequincey O, Chabaux F, Clauer N, Sigmarsson O, Liewig N, Leprun J-C (2002) Chemical mobillizations in laterites Evidence from trace elements and 2 U- " U- °Th disequilibria. Geochim Cosmochim Acta 66 1197-1210... 

Schuhmacher M, Hernandez M, Domingo JL, et al. 1996. A longitudinal study of lead mobilization during pregnancy concentration in maternal and umbilical cord blood. Trace Elements and Electrolytes 13 177-181. 

Reduction-oxidation is one of the most important processes controlling solubility and speciation of trace elements in soils, especially for those elements with changeable values, such as Cr, As and Se. Within normal ranges of redox potentials and pH commonly found in soils, the two most important oxidation states for Cr are Cr(III) and Cr(VI). Cr(III) is the most stable form of chromium and less soluble and nontoxic, but Cr(VI) is mobile, soluble and toxic. The main aqueous species of Cr(III) are Cr3+, Cr(OH)2+, Cr(OH)3° and Cr(OH)4" and the major aqueous species of Cr(VI)... 

The sulfides of trace elements in soils and sediments are also of importance in controlling the availability and mobility of trace elements, especially for land disposal of sulfide-rich sediments or anaerobic digested sludge. Due to the oxic nature in arid soils, most of the sulfur is present as sulfate thus, this problem may not be pressing. In most current SSD schedules, the majority of the sulfide forms are included in the organic bound or residual fractions. 

The partition index (IR, which will be discussed in details below) of Cd, Cu, Cr, Ni and Zn in both soils rapidly increased from time zero (calculated value) to one day and further to one year. This was especially true for Cr, Cu and to some extent Ni and Cd (Table 6.5). This result indicates that added trace metals are initially and rapidly transferred from the labile EXC fraction into the more stable fractions. Furthermore, IR of trace metals in native arid soils incubated under the saturated paste regime decreased at the end of year. This indicates mobilization of trace elements in these soils as saturation (Table 6.5). Also, it can be seen that IR decreased, for any given time, with an increase of the loading level (Table 6.5, Fig. 6.5). This means that higher additions of soluble metals result in higher metal content in the labile fractions and lower metal binding intensity in soils. 

Chemical remediation refers to the application of various minerals or chemicals to adsorb, bind, precipitate or co-precipitate trace elements and heavy metals in soils and waters thereby reducing their bioavailability, toxicity, and mobility. In situ immobilization refers to the treatment of contaminants in place without having to excavate the soils or waste, often resulting in substantial cost savings. However, in situ immobilization or extraction by these physicochemical techniques can be expensive and are often only appropriate for small areas where rapid and complete decontamination is required. 

Violante A, Krishnamurti GSR, Pigna M (2008) Mobility of trace elements in soil environments. In Violante A, Huang PM and Gadd G (eds) Wiley-JUPAC series on biophysico-chemical processes of metals and metalloids in soil environments. John Wiley Sons, Hoboken, USA Waltham AC, Eick MJ (2002) Kinetic of arsenic adsorption on goethite in the presence of sorbed silicic acid. Soil Sci Soc Am J 66 818-825 Waychunas GA, Fuller CC, Rea BA, Davis J (1996) Wide angle X-ray scattering (WAXS) study of two-line ferrihydrite structure Effect of arsenate sorption and counterion variation and comparison with EXAFS results. Geochim Cos-mochim Acta 60 1765-1781... 

Bruand A (2005) Toward conditions favourable to mobility of trace elements in soils. C R Geosci 337(6) 549-550... 

The geology not only provides the chemical source for trace-element mobility but it also provides the physical framework for water-flow paths. The structural properties of the rocks, the porosity, permeable fractures, provide for water-mineral reaction and element mobility. The geomorphology contributes to water-table levels, aquifer permeability, surface-water travel times, and time periods for erosion and sediment transport. Examples of... 

This contribution summarizes state-of-the-science with respect to USGS research on the hydrogeochemistry of trace-element mobilization and attenuation from mineralized areas during transport in surface and ground waters. The primary aspects are ... 

Table 3. Content of mobile forms of trace elements in rocks ofSpitzbergen Island, number of rocks = 10 (after Dobrovolsky, 1994).

The extraction by 1N NCI yields 5-10% of total heavy metal content. In case of Fe and Mn, these values are even higher. The maximum contents of mobile fractions of trace elements are monitored in the upper horizon. Thus, the role of evapotranspiration barrier in biogeochemical migration of elements in Dry Desert ecosystems pays a very important role in pollutants exposure. 

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