Degradation of terrestrially derived macromolecules in the Amazon River

Autor(es)

Ward, Nicholas D. ^[1] ; Keil, Richard G. ^[1] ; Medeiros, Patricia M. ^[2] ; Brito, Daimio C. ^[3] ; Cunha, Alan C. ^[3] ; Dittmar, Thorsten ^[4] ; Yager, Patricia L. ^[2] ; Krusche, Alex V. ^[5] ; Richey, Jeffrey E. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Washington, Sch Oceanog, Seattle, WA 98195 - USA

^[2] Univ Georgia, Dept Marine Sci, Athens, GA 30602 - USA

^[3] Univ Fed Amapa, BR-68902280 Macapa, AP - Brazil

^[4] Carl von Ossietzky Univ Oldenburg, Max Planck Res Grp Marine Geochem, Inst Chem & Biol Marine Environm, D-26129 Oldenburg - Germany

^[5] Univ Sao Paulo, Ctr Energia Nucl Agr, BR-13400970 Piracicaba, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: NATURE GEOSCIENCE; v. 6, n. 7, p. 530-533, JUL 2013.
• Citações Web of Science: 158

Resumo

Temperate and tropical rivers serve as a significant source of carbon dioxide to the atmosphere(1-4). However, the source of the organic matter that fuels these globally relevant emissions is uncertain. Lignin and cellulose are the most abundant macromolecules in the terrestrial biosphere(5), but are assumed to resist degradation on release from soils to aquatic settings(6-8). Here, we present evidence for the degradation of lignin and associated macromolecules in the Amazon River. We monitored the degradation of a vast suite of terrestrially derived macromolecules and their breakdown products in water sampled from the mouth of the river throughout the course of a year, using gas chromatography time-of-flight mass spectrometry. We identified a number of lignin phenols, together with 95 phenolic compounds, largely derived from terrestrial macromolecules. Lignin, together with numerous phenolic compounds, disappeared from our analytical window following several days of incubation at ambient river temperatures, indicative of biological degradation. We estimate that the net rate of degradation observed corresponds to 30-50% of bulk river respiration. Assuming that a significant fraction of these compounds is eventually remineralized to carbon dioxide, we suggest that lignin and other terrestrially derived macromolecules contribute significantly to carbon dioxide outgassing from inland waters. (AU)

• Processo FAPESP: 08/58089-9 - The role of rivers on the regional carbon cycle
• Beneficiário: Maria Victoria Ramos Ballester
• Modalidade de apoio: Auxílio à Pesquisa - Programa de Pesquisa sobre Mudanças Climáticas Globais - Temático