Multi-proxy approach involving ultrahigh resolution mass spectrometry and self-organising maps to investigate the origin and quality of sedimentary organic matter across a subtropical reservoir

Autor(es)

Jeunon Gontijo, Erik Sartori ^{[1, 2]} ; Herzsprung, Peter ^[1] ; Lechtenfeld, Oliver J. ^{[3, 4]} ; Bueno, Carolina de Castro ^[2] ; Barth, Johannes A. C. ^[5] ; Rosa, Andre H. ^[2] ; Friese, Kurt ^[1]

Afiliação do(s) autor(es)

^[1] UFZ Helmholtz Ctr Environm Res, Dept Lake Res, Brueckstr 3a, D-39114 Magdeburg - Germany

^[2] Sao Paulo State Univ, UNESP, Inst Sci & Technol, Av Tres de Marco 511, BR-18087180 Sorocaba, SP - Brazil

^[3] UFZ Helmholtz Ctr Environm Res, Dept Analyt Chem, Permoserstr 15, D-04318 Leipzig - Germany

^[4] UFZ Helmholtz Ctr Environm Res, ProVIS Ctr Chem Microscopy, Permoserstr 15, D-04318 Leipzig - Germany

^[5] Friedrich Alexander Univ Erlangen Nurnberg FAU, Dept Geog & Geosci, GeoZentrum Nordbayem, Univ Str 40, D-91054 Erlangen - Germany

• Tipo de documento: Artigo Científico
• Fonte: Organic Geochemistry; v. 151, JAN 2021.
• Citações Web of Science: 0

Resumo

Humic substances (HS) in sediments play an important role in carbon and nutrient biogeochemical cycles and fate of contaminants in the environment. However, information regarding HS quality and transformations that may affect their behaviour in reservoirs is still limited. The aim of this investigation was to track sources and changes in sedimentary HS across a subtropical reservoir, connecting them to in lake processes and land-use influences. Surface sediments were collected at seven sampling sites in Itupararanga Reservoir (Brazil). Humic (HA) and fulvic (FA) acids (components of HS) were extracted from the sediment samples followed by in-depth characterisation via UV/VIS, fluorescence spectroscopy, elemental (C, N) and isotopic analysis (delta C-13, delta N-15), nuclear magnetic resonance (C-13 NMR) and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). All data were analysed by self organising maps. The results showed that samples from the upstream part of the reservoir were older and more decomposed. They likely originated from C3 land-plants (delta C-13 varied from -26.3 parts per thousand to -22.4 parts per thousand), having more aromatic, oxygen-poor (O/C < 0.5) and unsaturated compounds (H/C 1.1). In contrast, near-dam samples were younger and had larger contributions of autochthonous material. This was confirmed by oxygen-rich (O/C 0.5) and partly more unsaturated compounds for FA as well as oxygen poor and saturated compounds with H/C > 1.1 for HA. Self-organising maps pointed out these differences between upstream and dam areas and indicated that agriculture lands were related to microbiallyderived HS. Changes in HS composition revealed that internal reservoir processes may have influenced HS quality across the reservoir. (C) 2020 Elsevier Ltd. All rights reserved. (AU)

• Processo FAPESP: 18/20326-1 - Dissolução e toxicidade de nanopartículas de prata na presença de substâncias húmicas aquáticas e excretados de algas
• Beneficiário: André Henrique Rosa
• Modalidade de apoio: Auxílio à Pesquisa - Regular