Especiação, mobilidade e biodisponibilidade de arsênio, urânio e fósforo em diferentes ecossistemas usando técnica de gradientes difusivos em filmes finos (DGT)

Author(s)

José Lucas Martins Viana

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Química
• Defense date: 2024-02-28

Examining board members

Anne Hélène Fostier; Cassiana Carolina Montagner; José Roberto Guimarães; Marco Tadeu Grassi

• Advisor: Anne Hélène Fostier; Amauri Antonio Menegário

Abstract

In this Doctoral Thesis, the mobility, speciation, and bioavailability of chemical elements were assessed in various environments using the technique of Diffusive Gradients in Thin Films (DGT). In Chapter I, the speciation and mobility of arsenic (As) were evaluated in soils of soda lakes soils of the Pantanal using DGT. Arsenic concentrations of up to 2,337.5 µg L-1 were found in porewater, and DGT results showed that the soil of the region acts as a non-reactive matrix for As. The use of DGT also allowed the detection of up to 203.0 µg L-1 of AsIII. Bioaccumulation/bioconcentration factors of As determined through phytoplankton and zooplankton analyses showed limited assimilation capacity and a high potential for transformation of this element in highly contaminated lagoons. In Chapter II, DGT was employed to assess the vertical distribution of phosphorus (P) in soils treated with conventional and recyclable fertilizers. The results demonstrated the success of recycled fertilizers in releasing P in a controlled manner to the soil compared to conventional chemical fertilizers, indicating the potential of these new products to replace unsustainable sources of P in agriculture. In Chapter III, DGT was used to assess chemical processes governing the mobilization of uranium (U) on a microscopic scale in sediments. DGT was applied to sediments from a former uranium mine in Minas Gerais state and analysed using laser ablation coupled with inductively coupled plasma mass spectrometry, generating high-resolution 2D images of the elemental distribution on the DGT surface. The technique of Diffusive Equilibration in Thin Films (DET) was applied for the 1D mapping of element concentrations in interstitial waters. The results highlighted the importance of microniches in the mobilization of U and interactions with other metals such as Mn and Fe on a scale reached for the first time in this study. Overall, this thesis demonstrates the potential of DGT as an important technique in studies of element mobility in soils and sediments (AU)

• FAPESP's process: 19/18124-4 - Fluxes, speciation and bioavailability of arsenic at the water/sediment interface in alkaline lakes of the Pantanal of Nhecolândia using DGT
• Grantee: José Lucas Martins Viana
• Support Opportunities: Scholarships in Brazil - Doctorate