Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Accueil du site → Doctorat → Brésil → Solos carbonáticos e interações pedogeomorfológicas no semiárido baiano : da evolução da paisagem ao processo de desertificação

Universidade Federal de Minas Gerais (2021)

Solos carbonáticos e interações pedogeomorfológicas no semiárido baiano : da evolução da paisagem ao processo de desertificação

Rios Marcio Lima

Titre : Solos carbonáticos e interações pedogeomorfológicas no semiárido baiano : da evolução da paisagem ao processo de desertificação.

Auteur : Rios Marcio Lima

Université de soutenance : Universidade Federal de Minas Gerais

Grade : Doutor em Geografia 2021

Résumé partiel
In the Salitre River basin, in the state of Bahia, the interactions between semiarid climate and soils with calcic and calcretic horizons impose peculiar natural conditions in the composition of the landscape. This study proposes to relate materials and processes, mainly involving calcification in soils, dynamics, and evolution of slopes and desertification, analyzed from interrelated elements at different spatial scales. The objective is to understand the evolutionary dynamics and attributes of carbonate and their interaction with actual morphodynamics, aiming to investigate a possible process of desertification in progress. The research was carried out from a multiscale spatial investigation, using different techniques. At the macroscale, information was systematized on the environmental context of the middle course of the Salitre River basin and the interpretation of satellite images, aerial photographs, relief morphometry, and Monte Carlo simulation for soil loss in the area. At the mesoscale, the analyzes focused on the slope, with a morphological description of soil profiles in toposequence, quantitative studies related to linear erosion, and identification of natural and anthropogenic features. At the microscale, we used soil micromorphology techniques. An area of 80 km2 was delimited corresponding to a relief compartment called valley bottom depression (dfv), which, in a more general view, presents large whitish spatial spots, which predominantly represent powdery calcretes, calcrete saprolites, and subsurface calcic horizons (colluvial materials) exposed, which were pickled by erosive action. In the toposequence, the few spots with solum mainly constitute carbonates HAPLIC CAMBISOLS, supported by materials with high contents of Equivalent Calcium Carbonate (500 g kg-1, up to 900 g kg-1), representing one of the areas with higher content of secondary carbonates in soils in Brazil. Typical features of CaCO3 precipitation in the soil were found, such as calcitic coatings and hypocoatings, calcitic fillings and individualized and coalesced carbonate nodules, associated with the first phases of the formation of a pedogenic calcrete profile, consistent with the current conditions of the local semiarid climate.

Présentation

Version intégrale (17,6 Mb)

Page publiée le 4 janvier 2023