Dominance of in situ produced particulate organic carbon in a subtropical reservoir inferred from carbon stable isotopes

De Castro Bueno C, Frascareli D, Gontijo ES, van Geldern R, Rosa AH, Friese K, Barth J (2020)

Publication Type: Journal article

Publication year: 2020

Journal

Scientific Reports Nature Publishing Group: Open Access Journals - Option B

Book Volume: 10

Article Number: 13187

Journal Issue: 1

DOI: 10.1038/s41598-020-69912-0

Abstract

Sources of particulate organic carbon (POC) play important roles in aqueous carbon cycling because internal production can provide labile material that can easily be turned into CO2. On the other hand, more recalcitrant external POC inputs can cause increased loads to sedimentary organic matter that may ultimately cause CH4 release. In order to differentiate sources, stable isotopes offer a useful tool. We present a study on the Itupararanga Reservoir (Brazil) where origins of POC were explored by comparing its isotope ratios (δ¹³CPOC) to those of dissolved inorganic carbon (δ¹³CDIC). The δ¹³CPOC averaged around − 25.1‰ in near-surface waters, which indicates higher primary production inferred from a fractionation model that takes into account carbon transfer with a combined evaluation of δ¹³CPOC, δ¹³CDIC and aqueous CO2. However, δ¹³CPOC values for water depths from 3 to 15 m decreased to − 35.6‰ and indicated different carbon sources. Accordingly, the δ¹³CDIC values of the reservoir averaged around + 0.6‰ in the top 3 m of the water column. This indicates CO2 degassing and photosynthesis. Below this depth, DIC isotope values of as low as − 10.1‰ showed stronger influences of respiration. A fractionation model with both isotope parameters revealed that 24% of the POC in the reservoir originated from detritus outside the reservoir and 76% of it was produced internally by aqueous CO2 fixation.

Authors with CRIS profile

Carolina De Castro Bueno Lehrstuhl für Angewandte Geologie Robert van Geldern Lehrstuhl für Angewandte Geologie Johannes Barth Lehrstuhl für Angewandte Geologie

Involved external institutions

São Paulo State University / Universidade Estadual Paulista "Júlio de Mesquita Filho" (UNESP)

Brazil (BR) Helmholtz-Zentrum für Umweltforschung (UFZ) / Helmholtz Center for Environmental Research

Germany (DE)

How to cite

APA:

De Castro Bueno, C., Frascareli, D., Gontijo, E.S., van Geldern, R., Rosa, A.H., Friese, K., & Barth, J. (2020). Dominance of in situ produced particulate organic carbon in a subtropical reservoir inferred from carbon stable isotopes. Scientific Reports, 10(1). https://doi.org/10.1038/s41598-020-69912-0

MLA:

De Castro Bueno, Carolina, et al. "Dominance of in situ produced particulate organic carbon in a subtropical reservoir inferred from carbon stable isotopes." Scientific Reports 10.1 (2020).

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