The need for trace metal speciation in soils was recognised and its practice well established in agricultural laboratories long before the term “speciation” entered the literature of analytical or agricultural chemistry. The “species” concerned, and determined, in these early and continuing studies are the plant-available “species” involved in plant and animal nutritional deficiency disease and in plant and animal toxicity. The common perception of speciation as the study of the actual compounds in which elements occur in a material is a practicable one for materials that are solutions, as, for example, natural waters. This conception is too restrictive for general application. In most solid samples, including soils and sediments, the determination of chemical species is in most cases a difficult challenge and suitable means to characterize the actual chemical combination in soils and sediments in a broader view is necessary. In practice, for trace metals a more general definition of speciation is required to encompass the requirements of soil and sediment science, among others. Such a definition has been given  and is summarised as: Speciation is the identification and determination (or the description) of the defined species of an element that occur in a material. The species can be defined: 1- by their function, e.g. as “plant-available” or “exchangeable” forms, 2- by the operation designed to isolate and determine them e.g. as the species isolated in the soil solution obtained by centrifugation or displacement or the moderately reducible species isolated by a particular reagent and, 3- as a particular compound or oxidation state of an element e.g. as tributyltin or Cr3+. This chapter will focus on the speciation in soils and sediments using single and sequential extraction schemes. Although the defined “species” should preferably be referred to as “extractable forms”, the term speciation will be used throughout the text for facility.
|Number of pages||19|
|Journal||Techniques and Instrumentation in Analytical Chemistry|
|Publication status||Published - 1 Jan 1995|
- trace metals
- analytical chemistry
- agricultural chemistry