Environmental transfer of zinc in calcareous soils in zones near old mining sites with semi-aridic climate.

A study on the speciation and bioavailability of zinc in calcareous soils near an old mining site in semi-aridic conditions (S.E. Spain) is presented. The mobility of both solid particles and soluble compounds of zinc are considered. The processes governing zinc transfer from the element-rich zone to the neighbouring soils are strongly influenced by the semi-aridic climate, while the presence of a high proportion of carbonates is also an important factor in the mobilization of the metal. Reactions which take place in the solid-liquid-gas interfaces are discussed. Data were obtained using both conventional methods for element speciation and a recently reported method especially adapted to highly calcareous soils. The procedure allows to outline the main speciation forms of zinc in these soils. Data obtained by means of X-ray diffraction spectrometry and SEM - EDX analyzer are used to confirm the chemical results. (C) 1999 Elsevier Science Ltd. All rights reserved.