Fig. 1

Hydrograph overlayed with stream water ¹⁴C-CO₂ and ¹⁴C-DOC time series. a Hydrograph showing the stream specific discharge (q) in mm d⁻¹ (grey line) and stream water ¹⁴C-CO₂ (blue circles (discrete samples (d)) and bars with diamonds (time-integrated samples (ti))) and ¹⁴C-DOC (orange triangles), all expressed in %modern for the period May 2015–June 2016. The blue rectangle indicates the range in atmospheric ¹⁴C-CO₂ content in the northern hemisphere during 2015–2016, according to Graven et al. ⁶⁸ b scatterplot showing the stream water ¹⁴C-CO₂ and ¹⁴C-DOC as a function of riparian water table position (in metres below ground surface). The solid line represents the least square linear regression model, ¹⁴C-DOC = WT_R × −33.3 + 115.4, R² = 0.53, p = 0.02). The original ¹⁴C data are listed in the Supplementary Table 1