Tracing low-CO2 fluxes in soil incubation and 13C labeling experiments: A simplified gas sampling system for respiration and photosynthesis measurements

Witzgall, Kristina.; Hesse, B. D.,; Seguel, O.; OSES, ROMULO; Grams, T. E.,; Mueller, Carsten

Abstract

Quantifying carbon dioxide (CO2) fluxes between soil and atmosphere is key in understanding net ecosystem C exchange and biogeochemical C cycling in plant-soil systems. In ecosystems with low primary production and sparse vegetation, i.e. drylands or sub-polar regions, where C fluxes are small, measurement sensitivity is key—even so when measurements are combined with isotopic labeling. Here, we present a simplified gas sampling system developed to facilitate sampling and measurement of low soil CO2 fluxes as well as in-situ 13CO2 labeling in the same setup. The capacity of the system was tested in a set of feature tests along with gas measurements of dryland soil-biocrust systems. The system’s sensitivity to capture minor changes in CO2 concentration was confirmed in respiration and photosynthesis measurements of soil-biocrust systems, where fluxes down to 0.1 µmol CO2 m−2 s−1 were quantified. A balloon, implemented to counterbalance under-pressure build-up during gas withdrawal, mitigated 72% of pressure differences at sampling. The overall system volume was reduced to a minimum to limit contamination caused by residual air, and the design enabled one-step flushing and evacuation of system compartments and gas sample bags, successfully ruling out cross-contamination between samples. Ultimately, this system offers a flexible and accessible solution for CO2 measurements that can be applied not only on arid soils with low biological activity and turnover rates, but also on plant-soil systems. The modifications enabled larger, and thereby more representative, sample volumes to be collected while limiting incubation, contamination, and pressure effects on the intact soil system.

Más información

Título de la Revista: JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES
Volumen: 128
Número: 9
Fecha de publicación: 2023
Idioma: ingles
URL: https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2023JG007410
DOI:

https://doi.org/10.1029/2023JG007410

Notas: ISI