Halloysite versus gibbsite: Silicon cycling as a pedogenetic process in two lowland neotropical rain forest soils of La Selva, Costa Rica

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dc.contributor.author Kleber, M en
dc.contributor.author Schwendenmann, Luitgard en
dc.contributor.author Veldkamp, E en
dc.contributor.author Rößner, J en
dc.contributor.author Jahn, R en
dc.date.accessioned 2016-09-30T00:54:28Z en
dc.date.available 2006-10-01 en
dc.date.issued 2007-02-15 en
dc.identifier.citation Geoderma, 2007, 138 (1-2), 1-11 en
dc.identifier.issn 0016-7061 en
dc.identifier.uri http://hdl.handle.net/2292/30549 en
dc.description.abstract Halloysite and gibbsite, although known to require quite different conditions for their formation, commonly occur together in the same horizon in oxisols derived from andesitic parent materials in tropical Costa Rica. We selected two soils of similar parent material, but of different ages and soil moisture regimes to identify possible clues to the coexistence of these two minerals. We employed selective dissolution procedures, X-ray fluorescence analysis and X-ray diffraction on field moist and air dry bulk soil samples to investigate how mineralogy changes with depth. We further separated the size fraction < 2 μm by means of sedimentation after organic matter and iron oxide removal to obtain more specific information on the phyllosilicate mineralogy of the clay size fraction. We found both soils to be depleted of primary minerals and pedogenesis to have progressed to advanced weathering stages particularly in the subsoils. Gibbsite XRD signal intensities were linearly and significantly related to weathering indices, corroborating the residual nature of gibbsite as an endproduct of weathering processes. The Si-bearing quartz and kaolinite-group minerals were enriched in the topsoils, indicating (i) their independence from a primary mineral Si source and (ii) the existence of a mechanism capable of protecting them against the continuous tropical weathering pressure. As we found no indications for retrospective additions of soil material through mass movement or aeolian additions, we believe a vegetation dependent, biological pumping mechanism to be the most plausible explanation for the presence of silica bearing minerals in the La Selva topsoils. The vertical distribution of 1.0 nm halloysite and its accumulation in the lower reaches of the wetter alluvial soil suggest that this metastable mineral forms as a result of Si enrichment where the residence time of the pore water is long enough to allow for Si concentrations to exceed the halloysite precipitation threshold. Taken together, our evidence indicates gibbsite in the La Selva soils to be the endproduct of intense tropical weathering, while the presence of hydrated halloysite seems to have mainly kinetic reasons and is most probably coupled to the contemporary soil moisture regime. en
dc.description.uri http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000244795300001&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=6e41486220adb198d0efde5a3b153e7d en
dc.language English en
dc.publisher Elsevier en
dc.relation.ispartofseries Geoderma en
dc.rights Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher. Details obtained from http://www.sherpa.ac.uk/romeo/issn/0016-7061/ https://www.elsevier.com/about/company-information/policies/sharing en
dc.rights.uri https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm en
dc.subject Science & Technology en
dc.subject Life Sciences & Biomedicine en
dc.subject Soil Science en
dc.subject Agriculture en
dc.subject SOIL SCIENCE en
dc.subject halloysite en
dc.subject gibbsite en
dc.subject allophane en
dc.subject X-ray diffraction en
dc.subject silicon cycling en
dc.subject tropical soils en
dc.subject rain forest en
dc.subject KAOLINITE en
dc.subject SEQUENCE en
dc.subject CARBON en
dc.subject PRODUCTS en
dc.title Halloysite versus gibbsite: Silicon cycling as a pedogenetic process in two lowland neotropical rain forest soils of La Selva, Costa Rica en
dc.type Journal Article en
dc.identifier.doi 10.1016/j.geoderma.2006.10.004 en
pubs.issue 1-2 en
pubs.begin-page 1 en
pubs.volume 138 en
dc.description.version VoR - Version of Record en
pubs.author-url http://www.sciencedirect.com/science/article/pii/S0016706106002904 en
pubs.end-page 11 en
pubs.publication-status Published en
dc.rights.accessrights http://purl.org/eprint/accessRights/RestrictedAccess en
pubs.subtype Article en
pubs.elements-id 113225 en
pubs.org-id Science en
pubs.org-id School of Environment en
dc.identifier.eissn 1872-6259 en
pubs.record-created-at-source-date 2016-09-30 en
pubs.online-publication-date 2006-12-08 en

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