Trace element sorption kinetics

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... 

To properly understand the fate of trace elements in soils, and particularly to comprehend their mobility with time, kinetic investigations are necessary (Sparks, 1995). Their sorption by soils is often observed to be a multistep process involving an initial fast sorption followed by slow sorption, probably by diffusion into pores of inner soil surfaces (Kinniburgh and Jackson, 1981), due to the presence of surface sites of different reactivity and site preferences (Ainsworth et al., 1994). 

The kinetic reactions occurring in the sorption of Ni, Cd, and Zn on goethite during a period of 2 hours to 42 days at pH 6 were hypothesized to occur via a three-step mechanism using a Fickian diffusion model (1) sorption of trace elements on external surfaces (2) solid-state diffusion of trace elements from external to internal sites and (3) trace element binding and fixation at positions inside the goethite particle (Bruemmer et al., 1988). 

Cells R, Cox L, Hermosin MC, Cornejo J (1996) Retention of metamitron by model and natural particulate matter. Intern J Environ Anal Chem 65 245-260 Chaney RL (1989) Toxic element accumulation in soils and crops protecting soil fertility and agricultural food chains. In Bar Yosef B, Barrow NJ, Goldschmid J (eds) Inorganic contaminants in the vadose zone Springer, Heidelberg, pp 140-159 Charlatchka R, Cambier P (2000) Influence of reducing conditions on solubility of trace metals in contaminated soils. Water, Air Soil PoUut 118 143-167 Chien SH, Clyton WR (1980) Application of Elovich equation to the kinetics of phosphate release and sorption in soils. Soil Sci Am J 44 265-268... 

Ball, J. W., Jenne, E. A., and Nordstrom, D. K., WATEQ2—a computerized chemical model for trace and major element speciation and mineral equilibria of natural waters, in Jenne, E. A., ed., "Chemical Modeling in Aqueous Systems, Speciation, Sorption, Solubility, and Kinetics." Amer. Chem. 

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