HR: 1340h
AN: B33A-0841    [Abstracts]
TI: Measurement of Microbially Induced Transformation of Magnetic Iron Minerals in Soils Allows Localization of Hydrocarbon Contamination
AU: * Kappler, A
EM: andreas.kappler@uni-tuebingen.de
AF: Geomicrobiology Group, Center for Applied Geosciences (ZAG), University of Tuebingen, Sigwartstrasse 10, Tuebingen, 72076, Germany
AU: Porsch, K
EM: katharina.porsch@uni-tuebingen.de
AF: Geomicrobiology Group, Center for Applied Geosciences (ZAG), University of Tuebingen, Sigwartstrasse 10, Tuebingen, 72076, Germany
AU: Rijal, M
EM: moti-lal.rijal@uni-tuebingen.de
AF: Geophysics Group, Center for Applied Geosciences (ZAG), University of Tuebingen, Sigwartstrasse 10, Tuebingen, 72076, Germany
AU: Appel, E
EM: erwin.appel@uni-tuebingen.de
AF: Geophysics Group, Center for Applied Geosciences (ZAG), University of Tuebingen, Sigwartstrasse 10, Tuebingen, 72076, Germany
AB: Soil contamination by crude oil and other hydrocarbons represents a severe environmental problem, but often the location and extent of contamination is not known. Hydrocarbons, or their degradation products, can stimulate iron-metabolizing microorganisms, leading to the formation or dissolution of (magnetic) iron minerals and an associated change of soil magnetic properties. Therefore, the screening of soil magnetic properties has the potential to serve as an efficient and inexpensive tool to localize such contaminations.
In order to identify the influence of different biogeochemical factors on the microbially influenced changes of magnetic iron minerals after hydrocarbon contamination, oil spills were simulated in laboratory batch experiments. The parameters tested in these experiments included soils with different bedrocks, type and amount of added hydrocarbon, and microbiological parameters (sterile and autochthonous microorganisms). In order to follow the changes of the soil magnetic properties, the magnetic susceptibility of the samples was measured weekly.
First results show that changes in the magnetic mineralogy are caused by microbial activity, as sterile samples showed no changes. In the microbially active set-ups, the magnetic susceptibility increased or decreased up to 10% in comparison to the initial magnetic susceptibility within a few weeks. In one iron-rich soil even a decrease of the magnetic susceptibility of ~40% was observed. Although the amount and type of hydrocarbons did not effect the changes in magnetic susceptibility, DGGE fingerprints revealed that they influenced microbial communities.
These results show that the magnetic susceptibility changes in the presence of hydrocarbons and that this change is microbially induced. This suggests that the screening of soil magnetic properties can be applied to localize and assess hydrocarbon contamination. In order to understand the biogeochemical processes better, the change of the iron mineralogy will be followed by Moessbauer spectroscopy in future batch experiments. Furthermore, iron-metabolizing microorganisms are currently isolated and identified.
DE: 0416 Biogeophysics
DE: 0424 Biosignatures and proxies
DE: 0448 Geomicrobiology
DE: 0463 Microbe/mineral interactions
SC: Biogeosciences [B]
MN: 2007 Fall Meeting