Are hypersaline tidal flat soils potential silicon sinks in coastal wetlands?

Autor(es)

Sartor, Lucas Resmini ^[1] ; Graham, Robert C. ^[2] ; Ying, Samantha C. ^[2] ; Andrade, Gabriel R. P. ^[3] ; Montes, Celia Regina ^[4] ; Ferreira, Tiago Osorio ^[5]

Afiliação do(s) autor(es)

^[1] Fed Univ Sergipe UFS, Campus Sertao, Nossa Senhora Da Gloria, Sergipe - Brazil

^[2] Univ Calif Riverside, Dept Environm Sci, Soil & Water Sci Program, Riverside, CA 92521 - USA

^[3] Univ Estadual Norte Fluminense, Ctr Ciencias & Tecnol Agr, Campos Dos Goytacazes, RJ - Brazil

^[4] Univ Sao Paulo CENA USP, Ctr Nucl Energy Agr, Piracicaba, SP - Brazil

^[5] Univ Sao Paulo ESALQ USP, Luiz de Queiroz Coll Agr, Dept Soil Sci, Piracicaba, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Geoderma; v. 337, p. 215-224, MAR 1 2019.
• Citações Web of Science: 0

Resumo

Hypersaline tidal flats (HTF) are transitional ecosystems which play an important role over Si biogeochemistry in wetlands. Sources and sinks of Si in these ecosystems are directly dependent on pedogenesis and are strongly influenced by the readily soluble Si components, such as dissolved Si, adsorbed Si, and amorphous silicates. The aim of this study was to identify and assess the distribution of readily soluble Si pool in two HTFs on the Brazilian coast. We based our studies on sequential extractions of iron and silicon, modeling of the soil aqueous phase, and X-ray diffraction of the fine clay fraction. Our results show that mobile Si and adsorbed Si are present at very low levels in HTF soils, comprising < 3% of the readily soluble Si pool. Silicon associated with Fe oxyhydroxides is the second largest component of the readily soluble Si pool, making up 8.7-40.8% of the Si extractions. The correlation between the ferrihydrite fraction and Si associated with Fe oxyhydroxides indicates a large control of Si by ferrihydrite. Amorphous Si makes up the dominant fraction, comprising 59-90% of the Si extractions. SEM images show the presence of diatoms, sponges, and phytoliths in the soils. Precipitation of pedogenic opal seems to occur in the soils due to a dry season at both sites. The clay assemblages are composed of the mixed-layer kaolinite-smectite (K-S), kaolinite-illite (K-I), and illite-smectite (I-S), and lesser amounts of kaolinite (K) and smectite (S) end-members. The presence of these clays indicates that HTF soils are conducive to the formation of mixed-layer minerals, which partially control Si dynamics. Our data indicate that HTF soils tend to accumulate Si by adsorption, (co)precipitation, and reactions involving clay minerals. (AU)

• Processo FAPESP: 14/11776-2 - Caracterização do meio físico, geoquímica de Fe e s e dinâmica de alteração de minerais em solos de planícies hipersalinas da costa brasileira
• Beneficiário: Lucas Resmini Sartor
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 16/09024-8 - Modelagem de raios-X e técnicas de microscopia eletrônica aplicadas ao estudo de minerais em solos hipersalinos
• Beneficiário: Lucas Resmini Sartor
• Modalidade de apoio: Bolsas no Exterior - Estágio de Pesquisa - Doutorado
• Processo FAPESP: 16/21026-6 - Solos de áreas úmidas da costa brasileira (planícies hipersalinas e pradarias marinhas): pedogênese e biogeoquímica do Fe, Si e C
• Beneficiário: Tiago Osório Ferreira
• Modalidade de apoio: Auxílio à Pesquisa - Regular