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Title (Primary) Biogeochemistry of the sediment-water interface in the littoral of an acidic mining lake studied with microsensors and gel-probes
Author Koschorreck, M.; Brookland, I.; Matthias, A.;
Journal Journal of Experimental Marine Biology and Ecology
Year 2003
Department SEEFO;
Volume 285-286
Language englisch;
Keywords acidic mining lakes; DET; littoral; microsensors; sediment diagenesis
Abstract

Acidic mining lakes (pH<3) represent a big environmental issue in former lignite mining areas. The acidity status of such lakes is mainly governed by the fluxes and the turnover of iron. No data are known about the iron cycling at the sediment–water boundary in the littoral of acidic mining lakes. In order to study the microstratification of iron cycling at the sediment–water interface, existing microsensor and gel-probe techniques (diffusive equilibration in thin-films, DET) were adapted to the extreme conditions of a mining lake. Microprofiles of O2 and pH measured in situ by a profiler were compared with profiles measured in sediment cores immediately after sampling. The results indicate that microprofile measurements in cores from the littoral underestimate oxygen penetration into the sediment. Both advective pore water movement and pore water displacement during coring did influence concentration profiles. Measurement of sulfate and both ferric and ferrous iron was possible on a millimetre scale using DET. Based on different test measurements, a protocol for the application of gel probes for the analysis of iron and sulfate in acidic mining lakes was developed.

The combination of microsensor and DET data allowed the characterisation and localisation of iron turnover on a millimetre scale. As an example, results from the littoral of Mining Lake 111 (Lusatia, Germany) are presented. Pore water gradients indicated a flux of ferric iron and sulfate from the water into the sediment. There were no indications of iron reduction or oxidation in the uppermost 6 cm of the sediment. A relative comparison of the fluxes revealed that the iron and sulfur fluxes were probably driven by the formation of jarosite directly in the sediment.

ID 4982
Persistent UFZ Identifier http://www.ufz.de/index.php?en=20939&ufzPublicationIdentifier=4982
Koschorreck, M., Brookland, I., Matthias, A. (2003):
Biogeochemistry of the sediment-water interface in the littoral of an acidic mining lake studied with microsensors and gel-probes
J. Exp. Mar. Biol. Ecol. 285-286 , 71 - 84