In-situ transformations of heavy metal mineral phases in soils
This project was developping a new technology to analyze in-situ the phase transformations of heavy metal phases in anthropogenic contaminated soils and sediments. The potential contamination sources can be e.g. mining activities, metalurgy, industrial activities or shooting ranges. The dissolution and phase transformation determine the fate of these potential toxic metals in the environment. To the present day there are no studies about the behaviour of these initial deposited heavy metals. The approach of this work is to get information about the heavy metal behaviour under controlled and natural conditions.
The method was applied on one hand to investigate the dissolution behavior of selected mineral particles in an acidic forest soil. Lead oxide, copper concentrate and copper slag were used as test minerals. During the incubation time of up to 18 months, the lead oxide particles showed noticeable dissolutiion signs wheras the copper phases did not show significant dissolution signs. On the other hand the method was used to analyse the phase transformation of lead oxide particles in different soils. In calcareous soils the lead oxide particles showed significant formation of secondary mineral precipitates. By using micro-Raman spectroscopy and environmental scanning electron microscopy (ESEM) the newly formed phases could be identified as predominantely lead-hydroxy.-carbonates (hydrocerussite).
The new in situ method was able to provide comprehensive new data concerning the dissolution behavior of fine particles in field experiments. The results can be used for environmental risk assessments of contaminated sites as well as to refine risk models by providing widespread in-situ acquired data.
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