Effects of organic matter and microbial community structure on the availability and phytoremediation of BA (barite) in flooded soils

• Grant number: 19/02796-3
• Support type: Scholarships in Brazil - Doctorate
• Effective date (Start): May 01, 2019
• Effective date (End): February 28, 2022
• Field of knowledge: Agronomical Sciences - Agronomy - Soil Science
• Principal Investigator: Jussara Borges Regitano
• Grantee: Douglas Gomes Viana
• Home Institution: Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Universidade de São Paulo (USP). Piracicaba , SP, Brazil
• Associated scholarship(s): 19/22280-1 - Effect of Mn oxyhydroxides application on barite reduction (BaSO4) and availability of Ba in anoxic soils, BE.EP.DR

Abstract

Anthropogenic activities have led to contamination of soils with Potentially Toxic Elements (PTEs). Barium (Ba), for example, may accrue from the use of Barite (BaSO4) as a fluid in the drilling of oil wells. In flooded soils, obligate anaerobic microorganisms use sulfate as the final electron acceptors, reducing it to sulfide, thus making Ba available in the environment. Sulfate reduction is closely related to the content and type of organic material present in the soil, as this fraction acts as a reducing agent of the medium, which can become anoxic, affecting the structure of the microbial community and the availability of Ba. However, little is known about the dynamics of BaSO4 reduction and the role of organic fraction and microbial population in these processes. In view of the above, we hypothesized that the nature of organic carbon modulates the structure and diversity of the bacterial community, favoring the reduction of sulfate and the availability of Ba in flooded soils and, consequently, its phytoremediation. The extent of this effect will depend on the conditions of the reduction medium as well as the presence of sulfate reducing microorganisms. To test this hypothesis, we will study the effect of the nature of distinct organic residues on Ba availability and in the structure and diversity of the soil microbial community, moreover, we will also identify the presence of genes related to sulfate reduction. The effect of the microbial population and the organic source on the phytoremediation of Ba by Typha domingensis will also be studied. The results of this research will allow: i) the understanding of Ba dynamics of flooded soils, evincing the risk of its presence in the exchangeable form to the environment and to living beings; (ii) assist oil companies in the more appropriate use and disposal of Barite (Ba) wastes; and iii) improve Ba remediation techniques in flooded soils with its contamination and serve as the basis for research with other elements in reducing environments. (AU)