Interactions between arsenic species and natural organic matter of the saline-alkaline lakes of the Pantanal of Nhecolândia

• Grant number: 22/12982-1
• Support Opportunities: Scholarships abroad - Research Internship - Master's degree
• Start date: May 01, 2023
• End date: October 31, 2023
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Analytical Chemistry
• Principal Investigator: Anne Helene Fostier
• Grantee: Marianna Alves Cancian
• Supervisor: Yves Marie Pierre Henri Lucas
• Host Institution: Instituto de Química (IQ). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
• Institution abroad: Université de Toulon (UTLN), France
• Associated to the scholarship: 21/05927-1 - Speciation, bioaccumulation and biotransformation of arsenic by cyanobacteria (Arthrospira sp. and Anabaenopsis sp.) from the saline-alkaline lakes of the Pantanal of Nhecolândia, BP.MS

Abstract

Results obtained in the thematic project FAPESP 2016/14227-5 showed that: 1) the waters of the alkaline lakes of the Pantanal of Nhecolândia systematically present high concentrations of dissolved As (up to 3000 µg L-1); 2) Higher concentrations of dissolved As are generally found in lakes where the highest autotrophic activity occurs (green lakes) and which consequently have higher production of organic matter. The presence of natural organic matter (NOM) have been shown to play an important role in the complexation, modification of the oxidation state, bioavailability and mobility of trace elements. The NOM could therefore be a key point in the Arsenic cycle in the alkaline lakes, since it can influence mobility, bioavailability, and speciation. The present project aims to characterize and quantify the interactions between arsenic species, As(III) and As(V), and the natural organic matter of the saline-alkaline lakes of the Pantanal and thus better understand their role in the biogeochemical cycle of As in this ecosystem. The dissolved organic matter was collected from four alkaline saline lakes: two previously classified as eutrophic turbid (ET) (green lakes), one oligotrophic turbid (OT) (black lake), and one clear vegetated oligotrophic (CVO) (crystalline lake). The samples are presently stored in the Laboratory "IM2NP" of the University of Toulon (France), where an exploratory study on As/Dissolved Organic Matter relationship has already been performed on these samples. The different types of samples (crude solution of NOM and solutions generated from the tangential ultrafiltration of colloidal fractions of NOM) will be analyzed with the interaction of the species As(III) and As(V) by means of acid-base microtitration and fluorescence quenching. (AU)