Details zur Publikation
|Titel (primär)||Concentrations and geochemical fractions of rare earth elements in two different marsh soil profiles at the North Sea, Germany|
|Autor||Mihajlovic, J.; Giani, L.; Stärk, H.-J.; Rinklebe, J.|
|Journal / Serie||Journal of Soils and Sediments|
The purpose of this study was (1) to determine the vertical distribution of rare earth element (REE) concentrations, stocks, and geochemical fractions in two different marsh soil profiles and (2) to quantify the relations between REEs and soil properties.
Materials and methods
A sandy Fluvisol recently flooded by tidal water and a clayey Gleysol landward the dike impacted by fluctuating groundwater levels served as reference marsh soils. An aqua regia extraction was used to determine the concentrations of REEs; additionally, a sequential extraction procedure developed by the Commission of the European Communities Bureau of Reference was conducted to assess the geochemical fractions (exchangeable, reducible, oxidisable, residual fraction) of REEs. Both extractions were carried out according to genetic horizons. The stocks of REEs were calculated and the relations between physico-chemical soil properties and concentrations/mobility of REEs were quantified via correlation analysis.
Results and discussion
The aqua regia extractable REE concentrations and stocks of the Gleysol were about two times higher compared to the Fluvisol since the Gleysol was more clayey and REEs might adsorb onto clay minerals. We have detected small differences of REE concentrations and geochemical fractions between the horizons of the single profiles. Rare earth elements existed mainly in residual or reducible fraction, followed by oxidisable, and water soluble/exchangeable/carbonate bound fraction. The most striking difference between the two marsh soil profiles regarding the geochemical fractions was the higher residual fraction in the Fluvisol than in the Gleysol what seemed to be due to the lower aqua regia extractable concentration in the former.
The aqua regia extractable concentration as well as reduction and oxidation processes of (amorphous) iron and manganese complexes seemed to have the most important impact on the geochemical fractions of REEs in the studied marsh soil profiles. In future, those findings should be verified in further marsh soils worldwide. In particular, future studies should elucidate the specific release kinetics of REEs and their determining factors.
|Mihajlovic, J., Giani, L., Stärk, H.-J., Rinklebe, J. (2014):
Concentrations and geochemical fractions of rare earth elements in two different marsh soil profiles at the North Sea, Germany
J. Soils Sediments 14 (8), 1417 - 1433