Binding mechanisms and mobility of arsenic in wetland soils

DFG Arsen

Organic soils are of great importance for the runoff chemistry in catchment areas and can act as effective filters for arsenic. Little is known about binding forms of arsenic and mechanisms for accumulation and mobilization in organic soils. In previous studies these mechanisms were examined in terrestrial soils. Apparently As turnover in fens is mainly caused by reductive transformations and the formation of organic As species by methylation, as well as binding to the organic substance.

The goals of this project are:

1. Depth specific investigation of As bounding forms in two fens with different As content by sequential extraction.

2. Quantification of adsorption and desorption as well as hysteresis of As(III) and As(V) in fens with different As contents.

3. Examinations regarding the influences of iron cationic bridges to the sorption.

4. Determination of As methylation rates in fens with different As-contents

5. Analysis of As mobilisation mechanisms under anaerobic conditions through substrate induced change of respiration.

The work will be accomplished with samples from two different peatlands. The location „Schlöppnerbrunnen “at the Fichtelgebirge can be seen as a slightly As loaded fen, Gola di Lago stands for a heavily loaded site. The work performs substantial contributions for the evaluation of As-entries in catchment areas and for the biogeochemistry of As in organic soils.