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Tipo: Artigo de Periódico
Data do documento: 2019
Autor(es): APRILE, Fabio Marques
SIQUEIRA, Gilmar Wanzeller
DARWICH, Assad José
IRION, Georg Friedrich
Afiliação do(s) Autor(es): SIQUEIRA, G. W. Universidade Federal do Pará
Título: Sedimentary transport influences on diagenetic processes at the Amazon continental shelf, Brazil
Agência de fomento: CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Citar como: APRILE, Fabio Marques et al. Sedimentary transport influences on diagenetic processes at the Amazon Continental shelf, Brazil. Journal of Geography, Environment and Earth Science International, v. 20, n. 4, p. 1-16, 2019. DOI: http//:10.9734/JGEESI/2019/v20i430113. Disponível em: Acesso em:.
Abstract: This research aimed to correlate the sedimentary transport with the diagenetic processes in the coastal zone and Amazon Continental Shelf (ACS). Physical and physical-chemical parameters, trace element contents (Cr, Pb, Ni, Zn and Hg), and O2, CO2 and iron flux were determined in sediment and pore water. Sedimentary incubation (96 hours) and algorithms were applied to determine the variation of the activity coefficient (ΔI) and ionic strength (Fi) of the predominant chemical species, and to estimate the net production and mineralization of the organic matter (ΔCO2T) in the system. There are not many studies applying incubation tests to identify the diagenetic processes, especially in fluvial-marines sediments. The results showed a strong zonation associated to the transport and deposition processes, influenced mainly by the grain-size and texture of sediment and fluvial streams. The distribution of trace elements followed the trend of the sedimentary pattern, with higher levels of metals in the deposits of clay minerals and organic matter. A factor of weight (Fw), calculated to establish the degree of importance of each parameter under the distribution and mobility of trace elements, suggests that the mobility of Cr, Ni and Zn is controlled by depth, clay and organic compounds contents, and concentration of dissolved oxygen.The vertical flow of O2 and CO2 and the Fe2+/Fe3+ ratio in the pore water suggest a predominance of organic matter oxidation in the sedimentary layer between 0.0 and 0.2 m, with partially anaerobic mineralization of the sediments below 0.4 m. Increases in trace element concentrations were observed in iron reduction zones, indicating processes of desorption of oxides and hydroxides of Fe and mineralization of organic matter. The extrapolation of the results of the incubation test to the studied system allowed to establish three hypotheses related to the diagenetic processes: 1) the flow of marine currents may be allowing the aerobic oxidation in the sandy sediments, with the nitrification route more accentuated than the ammonification route; 2) in the region of the coastal zone and inner continental shelf the routes of oxidation and reduction may be alternating according to the physical-chemical factors and seasonality; 3) in the coastal zone and inner shelf the net mineralization rate exceeded the net production rate of the organic matter (ΔCO2T >0).
Palavras-chave: Pore water
Net productivity
Sedimentary characterization
Diagenetic processes
Amazon continental shelf
Título do Periódico: Journal of Geography, Environment and Earth Science International
ISSN: 2454-7352
País: Inglaterra
Instituição: SCIENCEDOMAIN International
Tipo de Acesso: Acesso Aberto
Fonte URI: Disponível na internet via correio eletrônico:
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