Trace elements assessing mobility

To assess the environmental bioavailability, mobility and geochemical cycling of trace elements in soil, analyses of soil pore water composition are frequendy more instructive than those from whole soil or soil extracts. The validity of this concept... 

Leaching and extraction tests are used widely to assess trace element mobility and phytoavailability, as reviewed by Krishnamurti and Naidu hi Chapter 11. 

Leaching and extraction tests are widely used for assessing trace element mobility and phytoavailability. As measurements in these protocols are made in equilibrium conditions, only thermodynamic information is obtained. However, kinetic extraction—desorption studies are a more correct approximation to the distribution of species in natural media. The desorption rate constants of the trace elements in sediments and soils can be related to their mobility and toxicity. Detailed studies are needed in this area. 

Assessment of the toxicity of a chelator should in principle be done in an adequate model of the target population of iron-loaded patients. Observations with subjects that lack excessive iron stores may be based on unrealistic concentrations of the uncomplexed chelator, or alternatively show effects of removal of needed baseline iron stores. For example, it is not yet clear whether toxic effects of the hydroxypyridones are an inherent property of the agents themselves, a result of chelation of iron or other trace elements at strategic cellular locations, or a consequence of the mobilization of iron in toxic form. Toxicity of these compounds in animal studies has not been observed to the same extent in significant experience with patients... 

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