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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Flooding effect on mineralogical and geochemical changes in alkaline-sodic soil system of northern Pantanal wetlands, Brazil

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Oliveira Junior, Jairo C. [1] ; Andrade, Gabriel R. P. [2] ; Barbiero, Laurent [3, 4] ; Furquim, Sheila A. C. [5] ; Vidal-Torrado, Pablo [6]
Total Authors: 5
[1] Univ Fed Parana, Soil & Engn Dept, BR-80035050 Curitiba, Parana - Brazil
[2] Univ Estadual Norte Fluminense, Soil Lab, Campos Dos Goytacazes - Brazil
[3] Univ Sao Paulo, Ctr Energia Nucl Agr, Lab Ecol Isotop, Piracicaba - Brazil
[4] Geosci Environm Toulouse, Toulouse - France
[5] Univ Fed Sao Paulo, Dept Ciencias Ambientais, Diadema - Brazil
[6] Univ Sao Paulo, Dept Soil Sci, Piracicaba - Brazil
Total Affiliations: 6
Document type: Journal article
Source: European Journal of Soil Science; AUG 2019.
Web of Science Citations: 0

In the northern Pantanal wetlands of Brazil, alkaline sodic soils play a significant role in the ecological functioning of the region, but little is known about their mineralogical equilibria in current flooding dynamics, which is necessary for good management of these areas. This study focused on a transition between sodic and non-sodic soils, identified by low frequency electromagnetic induction survey. Samples of B horizons from alkaline-sodic and non-sodic soils were analyzed via soil solution from saturated paste, decomposition of X-ray diffraction (XRD) patterns and transmission electron microscopy with X-ray dispersive energy spectroscopy (TEM-EDS) analysis. The transition between alkaline-sodic and non-sodic soils matches with the transition between flooded and non-flooded areas. The soil solution shows a concentration factor of about 40 along this transition. The formation of sodic soils results from an accumulation by evaporation of solutions with a positive calcite residual alkalinity (RA(calcite)), probably imposed by the chemistry of the Sao Lourenco River. An increasing Na:Ca ratio caused solonization of the exchange complex. These alkaline-sodic soils, however, can be interpreted as declining soils in the current context with an evacuation of soluble salts during flood cycles. The detailed investigation of the fine clay fraction (< 0.2 mu m) using full profile modelling and decomposition of XRD patterns and TEM-EDS analysis demonstrates gradual transformations of trioctahedral to dioctahedral smectite by Mg - Al substitutions on octahedral sites, leading to the prevalence of kaolinite-smectite interstratified minerals when the conditions become more acidic via the solodization process. Highlights Clay minerals of alkaline-sodic soil have been altered due to flooding dynamic. Clay minerals are a useful tool for understanding environmental changes. Interstratified clay minerals result from current acidification. The evolution of soil mineral suite is related to the environmental changes. (AU)

FAPESP's process: 11/11905-9 - Spatial characterization and genesis of sodic soil in the region of Barão do Melgaço, Pantanal Mato-Grossense
Grantee:Jairo Calderari de Oliveira Junior
Support type: Scholarships in Brazil - Doctorate
FAPESP's process: 13/09192-0 - Saline lakes in the Pantanal of Nhecolândia: Hydro-bio-geochemistry of a singular wetland
Grantee:Laurent Barbiero
Support type: Regular Research Grants
FAPESP's process: 09/54372-0 - Soils of northern Pantanal: distribution, characterization, genesis, and current functioning
Grantee:Pablo Vidal Torrado
Support type: Regular Research Grants
FAPESP's process: 17/23301-7 - Soil and surface water alkaline systems in the Nhecolândia, Pantanal: Hydro-biogeochemical functions
Grantee:Janaina Braga Do Carmo
Support type: Research Grants - Visiting Researcher Grant - International
FAPESP's process: 11/13924-0 - Genesis and characterization of clay minerals from mangrove soils of Brazilian coast
Grantee:Gabriel Ramatis Pugliese Andrade
Support type: Scholarships in Brazil - Doctorate