Soil Biology and Biochemistry, Feb, 2014, Vol.69, p.187(10)
To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.soilbio.2013.10.040 Byline: Dorte Dibbern, Andreas Schmalwasser, Tillmann Lueders, Kai Uwe Totsche Abstract: Plants introduce abundant carbon into soils, where it is mineralised and sequestered. Proportions of this fresh organic carbon introduced to top soils can be relocated to deeper soil layers and even to groundwater by event-driven transport upon heavy rainfalls or after snowmelt. It is assumed that a significant fraction of this flux involves biocolloids and possibly microbial biomass itself. However, the nature of such transported microbes, their origin and the mechanisms of their mobilisation are still poorly understood. Here, we provide primary evidence that specific microbial populations are exported from top soils upon seepage events. At an experimental maize field, we have analysed the composition of mobilised bacterial communities collected in seepage water directly after snowmelt in winter at different depths (35 and 65 cm), and compared them to the corresponding bulk soil microbiota. Using T-RFLP fingerprinting and pyrotag sequencing, we reveal that mostly members of the Betaproteobacteria (Methylophilaceae, Oxalobacteraceae, Comamonadaceae), the Alphaproteobacteria (Sphingomonadaceae, Bradyrhizobiaceae), the Gammaproteobacteria (Legionellaceae) and the Bacteroidetes (Sphingobacteriaceae) were mobilised, all characteristic taxa for the rhizoplane. This highlights the importance of preferential flow along root channels for the vertical mobilisation and transport of microbes. Although the estimated quantitative fluxes of bacterial biomass carbon appeared low, our study allows for an improved understanding of the links between top soil, subsoil, and groundwater microbiota, as well as carbon fluxes between soil compartments. Author Affiliation: (a) Institute of Groundwater Ecology, Helmholtz Zentrum Munchen - German Research Center for Environmental Health, Ingolstadter Landstr. 1, 85764 Neuherberg, Germany (b) Institute of Geosciences, Department of Hydrogeology, Friedrich-Schiller-Universitat Jena, Burgweg 11, 07749 Jena, Germany Article History: Received 19 August 2013; Revised 16 October 2013; Accepted 17 October 2013
Hydrogeology ; Soil Microbiology ; Groundwater ; Soils ; Soil Carbon
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