Changes in soil iron biogeochemistry in response to mangrove dieback

Author(s)

Queiroz, Hermano Melo ; Ferreira, Tiago Osorio ; Asensio Fandino, Veronica ; Barbosa Ferraz Bragantini, Isadora Okuma ; Barcellos, Diego ; Nobrega, Gabriel Nuto ; Ferreira, Amanda Duim ; de Oliveira Gomes, Luiz Eduardo ; Bernardino, Angelo Fraga

• Document type: Journal article
• Source: BIOGEOCHEMISTRY; v. 158, n. 3, p. 16-pg., 2022-02-11.

Abstract

Fe biogeochemistry is associated with important ecosystem services provided by mangrove forests, including carbon sequestration and the retention of potentially toxic elements. The biogeochemical processes controlling Fe fate in mangroves are naturally affected by the soil geochemical environment, which controls Fe dynamics. However, ongoing climate changes and the associated extreme weather events may drastically affect the biogeochemistry of this important micronutrient for both terrestrial and oceanic environments. Therefore, this study aimed to evaluate how massive mangrove mortality after an extreme weather event altered the Fe dynamics in mangrove soils. The results show a significant decrease in soil carbon stock in the dead mangrove forests (25 kg m(-2)), as compared with the undisturbed forests (37 kg m(-2)). In addition, we observed a substantial Fe loss (greater than 50% of soil Fe forms, i.e., 17,000 mg kg(-1)) in the dead mangrove soils, which was associated with pyrite (9000 mg kg(-1)) and low crystallinity Fe oxyhydroxides (2400 mg kg(-1)). These impacts led to a decrease in the pyritization in soils, which resulted in a loss of 170 tons of Fe from 500 ha of dead mangrove forests within one year. Thus, the pyritization process may critically compromise a mangrove forests' ability to immobilize pollutants (e.g., metals) and sequester carbon in the long term, thereby altering their ability to provide these ecosystem services. Overall, our results revealed that the Fe biogeochemical cycle of mangrove forests is very sensitive to future climate change scenarios and increased extreme weather events. (AU)

• FAPESP's process: 19/14800-5 - Estuarine plants and their control in metals biogeochemistry in soils impacted by the `Mariana disaster´
• Grantee: Amanda Duim Ferreira
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 19/02855-0 - Redox fluctuations, iron and heavy metals dynamics in soils from Rio Doce estuary after the "Mariana (MG) disaster": an experimental approach
• Grantee: Diego Barcellos
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 18/04259-2 - Iron biogeochemistry and its control on dynamics of trace metals in the soils of Doce River estuary after the "Mariana disaster"
• Grantee: Hermano Melo Queiroz
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 19/19987-6 - Soils and plants of the Rio Doce estuary controlling the biogeochemistry of iron and metals in response to the Mariana (MG) disaster
• Grantee: Tiago Osório Ferreira
• Support Opportunities: Regular Research Grants