Coupling microbiological and iron biogeochemical alterations in soils of the Rio Doce estuary across different redox conditions

• Grant number: 22/04684-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: August 01, 2022
• End date: July 31, 2023
• Field of knowledge: Physical Sciences and Mathematics - Geosciences
• Principal Investigator: Diego Barcellos
• Grantee: Camila Hyo Ri Kim
• Host Institution: Instituto de Ciências Ambientais, Químicas e Farmacêuticas (ICAQF). Universidade Federal de São Paulo (UNIFESP). Campus Diadema. Diadema , SP, Brazil

Abstract

Several environmental, ecological, social, and economic impacts persist at the Rio Doce estuary, impacted by the constant arrival of upstream mine tailings derived from the collapse of the Fundão dam in 2015. The mine tailings are composed predominantly of iron (Fe) oxides, which may undergo reductive dissolution mediated by iron-reducing bacteria. This process may solubilize Fe and potentially toxic metals associated with Fe minerals from the tailings. Thus, the objective of this work is to test the hypothesis that communities of soil microorganisms would be similar when the soils are under anoxic or redox fluctuations conditions, but these communities may differ when the soils are under oxic conditions. To test this hypothesis, microbial communities will be characterized after submitting the Rio Doce estuarine soils to three different redox conditions, in a 20-day laboratory experiment, as follows: constantly anoxic (100% N2 and 0% O2), constantly oxic (79% N2 and 21% O2), and redox fluctuations within every 4 days of an alternation. Gas-tight tubes with the estuarine soils exposed to the different treatments will be harvested destructively over the experiment for microbial analysis. We will perform the extraction and sequencing of DNA (rRNA 16S) from the soil microorganisms for distinct treatments to determine microbial diversity, richness, and abundance. Results from this project will improve the comprehension of the mechanistic processes that couple microbial and iron biogeochemistry, in estuarine systems impacted by Fe-rich mine tailings, such as the Rio Doce and other impacted estuaries. (AU)