The environmental importance of iron speciation in soils: evaluation of classic methodologies

Author(s)

de Mello Gabriel, Gabriele Veronica ^{[1, 2]} ; Pitombo, Leonardo Machado ^[3] ; Tavares Rosa, Luana Maria ^{[1, 2]} ; Navarrete, Acacio Aparecido ^{[1, 3]} ; Botero, Wander Gustavo ^[4] ; do Carmo, Janaina Braga ^{[1, 3]} ; de Oliveira, Luciana Camargo ^{[1, 2]}

Affiliation

^[1] Fed Univ Sao Carlos UFSCar, Grad Sch Biotechnol & Environm Monitoring, Rodovia Joao Leme Santos, SP-264, Km 110, BR-18052780 Sorocaba, SP - Brazil

^[2] Fed Univ Sao Carlos UFSCar, Dept Phys Chem & Math, Rodovia Joao Leme Santos, SP-264, Km 110, BR-18052780 Sorocaba, SP - Brazil

^[3] Fed Univ Sao Carlos UFSCar, Dept Environm Sci, Rodovia Joao Leme Santos, SP-264, Km 110, BR-18052780 Sorocaba, SP - Brazil

^[4] Fed Univ Alagoas UFAL, Postgrad Program Chem & Biotechnol, BR-57309005 Maceio, Alagoas - Brazil

• Document type: Journal article
• Source: ENVIRONMENTAL MONITORING AND ASSESSMENT; v. 193, n. 2 JAN 15 2021.
• Web of Science Citations: 0

Abstract

Iron is an essential mineral and one of the most abundant in soils, presenting itself in the environment as ferrous and ferric ions. As each oxidation state of iron has a different role in the environment, its speciation in environmental studies is important. The determination of ferrous iron received great attention from soil chemists because of its important role in agriculture, in redox processes, and as an electron acceptor in the catalysis of organic matter. Methodologies with the use of colorimetric reagents to determine ferrous iron are divergent and not very clear. In this study, we compared two colorimetric reagents (1,10-phenanthroline and ferrozine) to determine the total concentration of iron, ferrous and ferric ions in soil, using simple and low-cost methodologies. The determination of ferrous and total iron with 1,10-phenanthroline colorimetric reagent, following published instructions, did not correlate with ferrozine method, presenting an erroneous quantification. After neutralizing the extract of 1,10-phenanthroline with NaOH, both colorimetric methods allowed to quantify with precision and high yield the amount of ferrous and total iron extracted from the soil. The oxidation states of iron have a different contribution and importance to the environment. In this sense, the improvement of a widely used methodology is crucial for the better study of iron speciation in soil. (AU)

• FAPESP's process: 13/50940-0 - Unravelling the sources and sinks of nitrous oxide (N2O) in sustainable bio-based agriculture
• Grantee: Janaina Braga do Carmo
• Support Opportunities: Program for Research on Bioenergy (BIOEN) - Regular Program Grants
• FAPESP's process: 17/03575-5 - Dynamics of production and consumption of methane by active microbiota in Amazonian wetlands
• Grantee: Acacio Aparecido Navarrete
• Support Opportunities: Scholarships in Brazil - Research Program on Global Climate Change - Young Investigators
• FAPESP's process: 16/16687-3 - Dynamics of production and consumption of methane by active microbiota in Amazonian wetlands
• Grantee: Acacio Aparecido Navarrete
• Support Opportunities: Research Program on Global Climate Change - Young Investigators
• FAPESP's process: 16/10796-5 - NATURAL WASTE AS ENVIRONMENTAL REMEDIATION: MICROCOSMS APPLICATION
• Grantee: Luciana Camargo de Oliveira
• Support Opportunities: Regular Research Grants