In situ fractionation and redox speciation of arsenic in soda lakes of Nhecolandia (Pantanal, Brazil) using the diffusive gradients in thin films (DGT) technique

Author(s)

Elias, Lucas Pellegrini ^[1] ; Menegario, Amauri Antonio ^[1] ; Hernandez, Amauris Hechavarria ^[2] ; Eismann, Carlos Eduardo ^[1] ; Martins Viana, Jose Lucas ^[2] ; Pedrobom, Jorge Henrique ^[1] ; de Oliveira Junior, Edson Geraldo ^[1] ; Barbiero, Laurent ^[3] ; Fostier, Anne Helene ^[1]

Affiliation

^[1] Sao Paulo State Univ UNESP, Environm Studies Ctr, Av 24-A, 1515, BR-13506900 Rio Claro, SP - Brazil

^[2] Univ Estadual Campinas, UNICAMP, Inst Chem, BR-13083970 Campinas, SP - Brazil

^[3] Univ P Sabatier, Geosci Environm Toulouse GET, OMP, CNRS, IRD, 14 Ave Edouard Belin, F-31400 Toulouse - France

• Document type: Journal article
• Source: Chemosphere; v. 288, n. 2 FEB 2022.
• Web of Science Citations: 0

Abstract

In situ fractionation and redox speciation of As in three different saline-alkaline lakes (green, black and crystalline lakes) in the Pantanal of Nhecolandia (Brazil) were performed by using Diffusive Gradients in Thin films (DGT). The results indicated that As is present mainly in dissolved form. Total As concentration was similar when using different filter membranes, demonstrating that the species adsorbed by DGT devices were <10 kDa. Higher concentrations of labile total As were observed in the center of the lakes, indicating that the nature of the organic matter influences the formation of As complexes. Total As concentrations determined by using ZrO2 DGT were consistent with As concentration in ultrafiltered water samples collected in the black lake. However, part of the data about As(III) obtained in grab samples contrasted with DGT results. The differences observed may indicate that alterations in the species occur during the storage period before analysis by ultrafiltration. As(III) concentrations measured by DGT in the black and crystalline lakes were 1-3 mu g L(-1)and 4-7 mu g L-1, respectively, accounting for only 4%-8% of the total DGT inorganic As. In the green lake, As(III) concentrations were significantly higher at the center (217 mu g L-1). Both the phytoplankton community and the dissolved organic carbon influence the As speciation and bioavailability in the lakes of Nhecolandia. The DGT approach used in the present work was able to perform As speciation and demonstrates that in situ sampling analytical techniques are essential in understanding As speciation and its behavior in complex natural aquatic systems. (AU)

• FAPESP's process: 16/14227-5 - Climatic changes and environmental impacts in wetlands of Pantanal region (Brazil): quantification, control factors and long term temporal modeling
• Grantee: Adolpho José Melfi
• Support Opportunities: Research Program on Global Climate Change - Thematic Grants
• FAPESP's process: 18/17069-7 - Evaluation of the biogeoavailability of metals and semimetals in soils using the diffusive gradient in thin film technique
• Grantee: Amauri Antonio Menegário
• Support Opportunities: Regular Research Grants
• 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
• FAPESP's process: 21/00572-0 - Determination, speciation and evaluation of bioavailability (transfers between water-soil-plant systems) of technologically critical elements (TCE)
• Grantee: Amauri Antonio Menegário
• Support Opportunities: Regular Research Grants