Banca de DEFESA: GABRIEL HENRIQUE MÁXIMO CLARINDO SILVA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : GABRIEL HENRIQUE MÁXIMO CLARINDO SILVA
DATE: 26/03/2024
TIME: 14:00
LOCAL: Ambiente Virtual
TITLE:

Organic matter dynamic and mineralogy of soils along contaminated mangrove forests: A
case study of Botafogo River estuary- PE, Brazil

KEY WORDS:

Contamination. Plant variability. Sulfides. Anthropogenic activities.

PAGES: 86
BIG AREA: Ciências Agrárias
AREA: Agronomia
SUBÁREA: Ciência do Solo
SPECIALTY: Química do Solo
SUMMARY:

The Botafogo River estuary, located on the north coast of Pernambuco, is considered one of the most important strips of mangroves in the Northeast region of Brazil. Its river basin contributes to the supply of drinking water for the entire metropolitan region of the state capital. However, anthropogenic impacts have been causing significant damage to the mangroves in this estuary for decades. After the installation of a chlor-alkali plant in the region in the 1960s, the release of highly toxic contaminants, such as mercury (Hg), into the Botafogo River contributed to the accumulation of this metal in mangrove forests. The work aimed to identify and relate the chemical attributes and mineralogy of the soil with plant diversity and position in the estuary, focusing on the role of organic matter (OM) and minerals in Hg dynamics. For this, soil samples were collected throughout different plant domains: Laguncularia racemosa, coexistence, Rhizophora mangle from the Botafogo river estuary. Then, the chemical and physical attributes of the soil and the total content of heavy metals were determined. Organic matter in the soil was analyzed by the evaluation of its origin, stability, and biochemical composition. Mineralogical characterization of the soil and S speciation were also carried out. The results indicate Hg contamination in the three forests, with concentrations following an increasing gradient towards the polluting source. The MO showed differences in origin, stability, and functional groups, mainly in relation to the R. mangle forest, located close to the river mouth. The characterization of MO also revealed a higher proportion of oxidized C, which can act on Hg retention. The silicate assemblage of the soils did not vary and highlighted the presence of kaolinite, quartz, muscovite, illite and smectite. Pyrite and carbonates were identified, but the presence of carbonates was restricted to areas close to the river mouth. Hg was found associated with pyrite, and S specification data revealed a possible contribution also from organic S, as a thiol. The quality of OM, soil mineralogy and specification of S made it possible to advance the discussion on the characterization of contaminated mangroves with an emphasis on the interaction with Hg, highlighting the role of geochemical filter of mineral and organic sulfides in the retention of this metal. Therefore, we emphasize the care to avoid changes in the biogeochemical conditions of the soil, mainly due to human activities, otherwise these soils will no longer play a role as a filter, but rather as a source of contaminants for other surrounding environments.

COMMITTEE MEMBERS:
Presidente - CAROLINE MIRANDA BIONDI
Interno - VALDOMIRO SEVERINO DE SOUZA JUNIOR
Externo à Instituição - RENATO MARQUES - UFPR
Externo à Instituição - FRANCIS HENRIQUE TENÓRIO FIRMINO - UFV
Externa à Instituição - JANE KELLY SILVA ARAUJO