Solid phase partitioning of metals in Managed Realignment soils: laboratory studies in timed soil sea-water batch mixtures

摘要

Geochemical interactions between agricultural soil and sea-water at a salt marsh restoration Managed Realignment site in Essex, UK were simulated through a series of laboratory experiments. Soil from the site was mixed with seawater for 0-30 days in batch reactors. The resulting soil residue was subjected to a modified version of the Tessier sequential extraction procedure involving leaching with 5 reagents of progressively increasing strength. Differences in total metals extracted by the series of sequential extractions in comparison to a single digest hindered interpretation of data. Analysis of the sequential extracts and residual sea-water for a suite of metals revealed that Na, Mg and K were sorbed from sea-water to the soils, and from the readily exchangeable fraction of the soil, Ba, Ca, Mn, Ni and Zn were depleted. In the more strongly held fractions extractability of a number of metals, most notably Al, Fe and K by acid leaches was observed to increase as a result of contact with sea-water. The extractability of the heavy metals Cr, Pb, Ni and Zn from these tightly held fractions was also observed to increase as a result of sea-water mixing. However, results imply that tidal inundation of the soils at the site will not result in significant leaching of metals to the environment. (C) 2001 Elsevier Science Ltd. All rights reserved. [References: 31]