Details

Autor(en) / Beteiligte

• Dalmagro, Higo J.
• Lathuillière, Michael J.
• Hawthorne, Iain
• Morais, Douglas D.
• Pinto, Osvaldo B.
• Couto, Eduardo G.
• Johnson, Mark S.

Titel

Carbon biogeochemistry of a flooded Pantanal forest over three annual flood cycles

Ist Teil von

• Biogeochemistry, 2018-06, Vol.139 (1), p.1-18

Ort / Verlag

Cham: Springer Science + Business Media

Erscheinungsjahr

2018

Link zum Volltext

Quelle

SpringerLink (Online service)

Beschreibungen/Notizen

• The Pantanal is the largest wetland in the world and yet little is known about the variability in carbon (C) dynamics across its flood seasons. We examined the effect of inundation on the C cycle in the 2013–2015 flood cycles illustrated by dissolved CO₂, CH₄, organic C (DOC) concentration measurements, and optical properties of dissolved organic matter (DOM) evaluated by absorbance and fluorescence spectroscopy with parallel factor analysis (PARAFAC). During the 2015 flood cycle, pCO₂ varied between 5973 and 14,292 µatm, with pCH₄ concentrations ranging between 2956 and 51,675 µatm respectively, with high temporal variability for both gases. The supersaturation of CO₂ and CH₄ in relation to the atmospheric equilibrium caused the system to behave as a net source of CO₂ and CH₄ to the atmosphere with evasion rates of 320 mg CO₂ m⁻² d⁻¹ and 20 mg CH₄ m⁻² d⁻¹, respectively. Mean DOC concentration was 7.0 ± 0.4 mg L⁻¹ and did not differ between flood cycles. Higher concentrations of DOC were measured at the start (rising floodwaters) and at the end (receding floodwaters) of flood cycles, while lower DOC concentrations were observed during the peak flood. The PARAFAC analysis indicated the presence of five DOM components: humic (C1 and C2) and fulvic type material (C3) showed the highest relative abundance (68.5% of the total PARAFAC component fluorescence), as well as protein-like material (C4 and C5) derived from microorganisms. Our measured diffusive flux levels were below the range of emissions found for wetlands and floodplains for CO₂, but were slightly higher for CH₄ relative to other studies in lakes and seasonally flooded areas of the Pantanal. The large variations in concentrations of CO₂, CH₄ and DOC and the optical properties of DOM during the course of each flood cycle suggest a close relationship between carbon and water cycles in this tropical wetland.