Dados do Trabalho

Título

CHANGES IN IRON-ORGANIC MATTER INTERACTIONS IN MANGROVE SOILS FOLLOWING AN EXTREME WEATHER EVENT

Resumo

Despite thriving in challenging environmental conditions, such as high salinity, anaerobic soils, and extreme tides, mangroves face significant threats from climate change, resulting in widespread forest loss. This research aimed to assess the impact of extreme weather events on iron-organic matter (Fe-OM) interactions in mangrove soils. The research was conducted in a protected area in Espírito Santo State, Southeast Brazil, where a severe drought followed by a sudden hailstorm event caused substantial forest mortality. To investigate the effects of these events, we performed wet-chemical fractionation of iron (Fe) to analyze its distribution in 1) organo-mineral complexes, 2) poorly crystalline oxides, and 3) crystalline oxides. Additionally, we determined the amount of Fe-associated organic carbon in both impacted and non-impacted mangroves. Our findings revealed a three-fold decrease in Fe concentration in impacted mangroves, from 10,193 to 3,604 mg kg-1, predominantly lost from the pools of poorly crystalline and crystalline Fe oxides. Furthermore, the proportion of Fe-associated organic matter decreased from 14.5 ± 6% of the total soil organic carbon in non-impacted mangroves to 7.8 ± 2.4% in the impacted mangrove, representing a loss of approximately 50% of Fe-associated organic matter. Our results show that a supposedly stable fraction of organic matter, protected by organo-mineral associations, can be readily lost due to changes in the biogeochemical environment caused by extreme weather events. These findings have significant implications for understanding the persistence of soil organic matter in mangrove soils, particularly with respect to organo-mineral interactions, a mechanism that has been understudied in mangrove soils.

Palavras-chave

Iron geochemistry, organo-mineral interactions, mineral-organic associations

Instituição financiadora

CNPq (processo: 305013/2022-0)

Agradecimentos

The authors would like to express their gratitude to the CLACS organizing committee.