Geophysics techniques on the evaluation of natural processes in the pedosphere, at different pedoenvironment and its contribution for digital soil mapping

• Ano de defesa: 2020
• Autor(a) principal: Mello, Danilo César de
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Biblioteca Digitais de Teses e Dissertações da USP
• Palavras-chave em Português: Gammaespectrometria; Gammaspectrometry; Geofísica; Geophysic; Pedologia; Pedology; Pedometria; Pedometry; Soil magnetic susceptibility; Susceptibilidade magnética do solo
• Link de acesso: http://www.teses.usp.br/teses/disponiveis/11/11140/tde-23032020-152907/

The use of geophysical techniques applied in geology has recently been used for soil science studies. However, most studies focus on attribute modeling and mapping, with little or no emphasis on understanding the processes that occur in the pedosphere, as well as on the interrelationship between the processes and environmental factors (geology, relief, pedogeochemistry and hydrology). The research was carried out aiming the use of proximal geophysical sensors (gamma and susceptibilimeter) for the understanding of naturally occurring processes in the pedosphere (pedogenetic, pedogeomorphological, pedogeochemical), the relationship of these processes with soil attributes and the contribution to digital soil mapping, highlighting the potential and limitation of the technique. The study area is located in São Paulo State - Brazil. The geophysical data were collected using field sensors using gammaspectrometer and susceptibilimeter, at 89 points. Also, augers were performed (0-20cm) in these same points to traditional physical-chemical analyses. These data were combined soil morphological description and classification in various profiles, geoprocessed and statistical analyses was undertaken using the softwares ArcGIS, SAGAGIS and R. The lithology strong contribute uranium, torium, potassium (radionuclides) content in and magnetic susceptibility (MS) in less evolved soil classes. On the other hand, in more evolved soil classes the pedogenesis had more influence in radionuclides content and MS. Pedogeomorphological processes affect distribution of radionuclides and MS by transport and deposition of materials and erosional effect, oncoming soil surface of parent material. The geochemical comportment of radionuclides and pedogeochemical pathways of ferrimagnetic minerals formation are controled by weathering and pedosphere conditions, wich drainage is one of the most important. Radionuclides had good correlation mainly with soil texture, while MS had with soil texture, CEC and Fe2O3. MS identified the transition areas between soil classes, lithology as well as radionuclides variation content, providing a potential tool for soil classes stratification and digital pedological mapping. For each particular pedoenvironment a conceptual model to interpret soil MS and radionuclides contentits and their relation with pedosphere processes, need to be stablish, once many variables, with different characteristics affect radionuclides content and distribution, as well as MS values.