Geochemical control of microbial Fe(III) reduction potential in wetlands: comparison of the rhizosphere to non-rhizosphere soil
dc.contributor.author | Weiss, Johanna V. | |
dc.contributor.author | Emerson, David | |
dc.contributor.author | Megonigal, J. Patrick | |
dc.date.accessioned | 2007-12-03T16:51:10Z | |
dc.date.available | 2007-12-03T16:51:10Z | |
dc.date.issued | 2004 | |
dc.description.abstract | We compared the reactivity and microbial reduction potential of Fe(III) minerals in the rhizosphere and non-rhizosphere soil to test the hypothesis that rapid Fe(III) reduction rates in wetland soils are explained by rhizosphere processes. The rhizosphere was defined as the area immediately adjacent to a root encrusted with Fe(III)-oxides or Fe plaque, and non-rhizosphere soil was >0.5 cm from the root surface. The rhizosphere had a significantly higher percentage of poorly crystalline Fe (66±7%) than non-rhizosphere soil (23±7%); conversely, non-rhizosphere soil had a significantly higher proportion of crystalline Fe (50±7%) than the rhizosphere (18±7%, P<0.05 in all cases). The percentage of poorly crystalline Fe(III) was significantly correlated with the percentage of FeRB (r=0.76), reflecting the fact that poorly crystalline Fe(III) minerals are labile with respect to microbial reduction. Abiotic reductive dissolution consumed about 75% of the rhizosphere Fe(III)-oxide pool in 4 h compared to 23% of the soil Fe(III)-oxide pool. Similarly, microbial reduction consumed 75201380% of the rhizosphere pool in 10 days compared to 30201340% of the non-rhizosphere soil pool. Differences between the two pools persisted when samples were amended with an electron-shuttling compound (AQDS), an Fe(III)-reducing bacterium (Geobacter metallireducens), and organic carbon. Thus, Fe(III)-oxide mineralogy contributed strongly to differences in the Fe(III) reduction potential of the two pools. Higher amounts of poorly crystalline Fe(III) and possibly humic substances, and a higher Fe(III) reduction potential in the rhizosphere compared to the non-rhizosphere soil, suggested the rhizosphere is a site of unusually active microbial Fe cycling. The results were consistent with previous speculation that rapid Fe cycling in wetlands is due to the activity of wetland plant roots. | |
dc.format.extent | 261662 bytes | |
dc.format.extent | 89–100 | |
dc.format.mimetype | application/pdf | |
dc.identifier.citation | Weiss, Johanna V., Emerson, David, and Megonigal, J. Patrick. 2004. "<a href="https://repository.si.edu/handle/10088/2994">Geochemical control of microbial Fe(III) reduction potential in wetlands: comparison of the rhizosphere to non-rhizosphere soil</a>." <em>FEMS Microbiology Ecology</em>, 48, (1) 89–100. | |
dc.identifier.uri | http://hdl.handle.net/10088/2994 | |
dc.language.iso | en_US | |
dc.relation.ispartof | FEMS Microbiology Ecology 48 (1) | |
dc.title | Geochemical control of microbial Fe(III) reduction potential in wetlands: comparison of the rhizosphere to non-rhizosphere soil | |
dc.type | article | |
sro.description.unit | serc | |
sro.identifier.itemID | 81171 | |
sro.identifier.refworksID | 96120 | |
sro.identifier.url | https://repository.si.edu/handle/10088/2994 |
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