Fig. 4: Time series and depth variation.
From: Mineral weathering is linked to microbial priming in the critical zone
a Time series of humification index (HIX), specific ultraviolet absorbance at 254 nm (SUVA254) and corrected dissolved organic carbon (DOC) fluxes (fDOC-corr) in the topsoil. HIX, SUVA254 and fDOC-corr show generally consistent temporal trends. b The priming effect (PE) at four soil depths. The periods for calculation are marked by yellow bands in Fig. 3 and Supplementary Figs. 7–9. The priming effect is calculated using corrected dissolved inorganic carbon (DIC) fluxes (fDIC-corr) and CO2 fluxes (fCO2) data, with lighter blue or orange representing basal soil-derived C fluxes and darker blue or orange representing “fresh” dissolved organic matter (DOM)-primed C fluxes (i.e., PE DOM). The PE DOM in the deep soil is much lower than at shallower depths, yet relative PE DOM is highest in the deep soil. The PE DOM can be used as a “control group” for further evaluation of the influence of mineral weathering on the priming effect. c–d Temporal and spatial variation in ion charge balance. Time series of CO2 partial pressure (PCO2) and O2 partial pressure (PO2) show inverse temporal trends, suggesting that soil organic matter (SOM) decomposition occurred at the expense of soil O2.
