Figure 3. Heterogeneity of newly formed organo-mineral associations.

(a) Box plots of ¹³C⁻/¹²C⁻ ratios obtained by NanoSIMS reflecting the number of evaluated regions of interest (ROIs) (medians, error bars indicate data range within 5th and 95th percentiles) and ¹³C values (dots) obtained by IRMS (medians, error bars indicate SEs, n=3). (b) ¹²C¹⁵N⁻/¹²C¹⁴N⁻ ratios obtained by NanoSIMS reflecting the number of evaluated ROIs (medians, error bars indicate data range within 5th and 95th percentiles) and ¹⁵N values (dots) obtained by IRMS (medians, error bars indicate SEs, n=3). Outliers are marked with asterisks. The ratios for an unlabelled clay-sized fraction were used to prove enrichment and are called natural abundance.