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Biotic and abiotic experimental identification of bacterial influence on calcium isotopic signatures
Author(s) -
Cobert Florian,
Schmitt AnneDésirée,
Calvaruso Christophe,
Turpault MariePierre,
Lemarchand Damien,
Collig Christelle,
Chabaux François,
Stille Peter
Publication year - 2011
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.5101
Subject(s) - chemistry , apatite , fractionation , environmental chemistry , dissolution , isotope fractionation , rhizosphere , abiotic component , weathering , bacteria , mineralogy , geochemistry , geology , chromatography , paleontology
In this study, we tested experimentally the influence of plant and bacterial activities on the calcium (Ca) isotope distribution between soil solutions and plant organs. Abiotic apatite weathering experiments were performed under two different pH conditions using mineral and organic acids. Biotic experiments were performed using either apatite or Ca‐enriched biotite substrates in the presence of Scots pines, inoculated or not with the rhizosphere bacterial strain Bulkholderia glathei PML1(12), or the B. glathei PML1(12) alone. For each experiment, the percolate was collected every week and analyzed for Ca concentrations and Ca isotopic ratios. No Ca isotopic fractionation was observed for the different abiotic experimental settings. This indicates that no Ca isotopic fractionation occurs during apatite dissolution, whatever the nature of the acid (mineral or organic). The main result of the biotic experiments is the 0.22 ‰ 44 Ca enrichment recorded for a solution in contact with Scots pines grown on the bacteria‐free apatite substrate. In contrast, the presence of bacteria did not cause Ca isotopic fractionation of the solution collected after 14 weeks of the experiments. These preliminary results suggest that bacteria influence the Ca isotopic signatures by dissolving Ca from apatite more efficiently. Therefore, Ca isotopes might be suitable for detecting bacteria‐mediated processes in soils. Copyright © 2011 John Wiley & Sons, Ltd.