Status: this preprint is open for discussion and under review for Biogeosciences (BG).
The oxygen budget of a peatland – new approach to estimating ecosystem oxidative ratio
Fred Worrall,Gareth Clay,Catherine Moody,and Catherine Hirst
Abstract. The oxidative ratio (OR) of an ecosystem in the terrestrial biosphere is defined as the ratio of the O2 released from that ecosystem to the CO2 adsorbed by that ecosystem. This study proposes that the OR of a terrestrial ecosystem could be calculated for the C budget of a peatland environment where stoichiometry and thermodynamics are constrained. Using detailed elemental analysis within an ecosystem with a known C and N budget it is possible to understand the amount of O2 consumed.
The study shows that, for the study site, although the majority of the O2 is consumed in the processing of organic-C (68 %), 32 % of O2 consumption is due to oxidation of NH4. The total amount of O2 consumed by organic C processing is not dependent upon the pathway after surface peat formation: O2 consumption is independent of production of DOC or CH4 or of deep peat. This approach shows that allowing for stoichiometric, energy and energy transfer efficiency constrains the ecosystem OR = 0.88. The calculated OR is consistent with disproportionation of C occurring in the environment. The implication of OR < 1 is that the annual flux of C to the terrestrial biosphere has been underestimated by 12 %.
Received: 27 Mar 2025 – Discussion started: 22 Apr 2025
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Understanding global carbon budgets requires a knowledge of the balance between carbon dioxide and oxygen gas fluxes – oxidative ratio (OR). The OR has proved difficult to measure for terrestrial environments. We present a novel method for measuring OR using an ecosystem's carbon budget and organic matter elemental composition. We found an OR of 0.88, significantly lower than the IPCC's assumed 1.1. This lower OR value implies that terrestrial biosphere carbon budgets have been underestimated.
Understanding global carbon budgets requires a knowledge of the balance between carbon dioxide...
