Repositorio
Institucional

Matus, Francisco

Stock, Svenja#Eschenbach, Wolfram#Dyckmans, Jens#Merino, Carolina#Najera, Francisco#Koester, Moritz#Kuzyakov, Yakov#Dippold, Michaela A.

Ferrous Wheel Hypothesis: Abiotic nitrate incorporation into dissolved organic matter

PERGAMON-ELSEVIER SCIENCE LTD

GEOCHIMICA ET COSMOCHIMICA ACTA

en

We evaluated the abiotic formation of dissolved organic nitrogen (DON) by the fast reaction of iron (Fe) with nitrate (NO3-) in the dissolved organic matter (DOM) of volcanic soils in a temperate rainforest (>5000 mm precipitation per year). During five days, the educts and products of abiotic reactions under anoxic conditions were measured in a microcosm experiment depending on the Fe and NO3- concentrations. A control zero-Fe was not used because there was no chemical reaction with nitrate addition. Using a novel technique of automated sample preparation for inorganic N (SPIN) attached to a membrane inlet quadrupole mass spectrometry (MIMS), the N-15 abundances and inorganic N concentrations were determined directly in aqueous solutions. The results were explained in the context of the Ferrous Wheel Hypothesis which states that Fe(II) is utilized to reduce NO3- to nitrite (NO2-) that is incorporated into DOM. Fe(II) is regenerated from Fe(III) in anaerobic soil microsites. Here we tested one part of this hypothesis, the processes occurring in DOM (instead of soil organic matter). Using the SPIN-MIMS technique, we could overcome Ferrous Wheel Hypothesis criticism regarding possible Fe interference during NO3- analysis. The total recovery of N-15 added as NO3- fluctuated between 63 and 101%, and the remaining N-15 was measured as gaseous N2O. The N-15-labelled NO3- added decreased immediately after 15 min of incubation. After five days of incubation, approximately 25% of the labelled NO3- (e(- )acceptors) added was transformed to DON in the presence of a high amount of Fe(II) (e(-) donors). Small amounts of N2O and CO2 provided further evidence of NO3- reduction and DOM oxidation, respectively. From these results, we propose a new theoretical model that includes the Ferrous Wheel Hypothesis, where only the transformation of NO3- to DON was proven. The present results explain the high retention of NO3- in DOM from volcanic soils in ecosystems with high precipitation. (C) 2018 Elsevier Ltd. All rights reserved.

Artículo original

We acknowledge the Division of Agricultural Soil Science and Biogeochemistry of Agroecosystems at the University of Gottingen. We thank the KOSI (Centre for Stable Isotope Research and Analysis) of the University of Gottingen for performing all stable isotope measurements. We also acknowledge the National Commission for Scientific and Technological Research (CONICYT-FONDECYT, Chile grant No 1170119 and Postdoctoral CONICYT-FONDECYT, Chile grant No 3160513) and the Network for Extreme Environments Research (NEXER, Chile) for the financial support. We acknowledge to Nicolas Pacheco from CONAF and Roberto Godoy from Austral Univeristy of Chile for helping us during soil sampling campaing. We are very thankful to the Editor and three reviewers for their careful and detailed helpful contributions and comments on the manuscript.

Agradecemos a la División de Ciencias del Suelo Agrícola y Biogeoquímica de Agroecosistemas de la Universidad de Göttingen. Agradecemos al KOSI (Centro de Investigación y Análisis de Isótopos Estables) de la Universidad de Göttingen por realizar todas las mediciones de isótopos estables. También agradecemos a la Comisión Nacional de Investigación Científica y Tecnológica (CONICYT-FONDECYT, Chile, beca n.° 1170119 y beca postdoctoral CONICYT-FONDECYT, Chile, n.° 3160513) y a la Red de Investigación en Ambientes Extremos (NEXER, Chile) por el apoyo financiero. Agradecemos a Nicolás Pacheco de CONAF y a Roberto Godoy de la Universidad Austral de Chile por su ayuda durante la campaña de muestreo de suelos. Agradecemos profundamente al Editor y a los tres revisores por sus cuidadosas, detalladas y útiles contribuciones y comentarios al manuscrito.

10.1016/j.gca.2018.11.020

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Fe redox wheel# Abiotic N reaction# Dissolved organic nitrogen# N sequestration

http://dx.doi.org/10.1016/j.gca.2018.11.020

Geochemistry & Geophysics

rueda redox de Fe# Reacción abiótica de N# Nitrógeno orgánico disuelto# secuestro de norte

Ciencias del suelo

Química Analítica

Geociencias

WOS:000453771600030

Ferrous Wheel Hypothesis: Abiotic nitrate incorporation into dissolved organic matter

Artículo original

version publicada

PERGAMON-ELSEVIER SCIENCE LTD

GEOCHIMICA ET COSMOCHIMICA ACTA

Geoquímica y Geofísica

0016-7037

en

University of Gottingen#ANID FONDECYT 3160513#NEXER#

ANID CONICYT FONDECYT 1170119;ANID CONICYT FONDECYT 3160513

NEXER

We acknowledge the Division of Agricultural Soil Science and Biogeochemistry of Agroecosystems at the University of Gottingen. We thank the KOSI (Centre for Stable Isotope Research and Analysis) of the University of Gottingen for performing all stable isotope measurements. We also acknowledge the National Commission for Scientific and Technological Research (CONICYT-FONDECYT, Chile grant No 1170119 and Postdoctoral CONICYT-FONDECYT, Chile grant No 3160513) and the Network for Extreme Environments Research (NEXER, Chile) for the financial support. We acknowledge to Nicolas Pacheco from CONAF and Roberto Godoy from Austral Univeristy of Chile for helping us during soil sampling campaing. We are very thankful to the Editor and three reviewers for their careful and detailed helpful contributions and comments on the manuscript.

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hibrida#verde

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