Fig. 2: Biogeographical distribution of microbial N2O production sources in the riparian zone and riverbed sediments along transects of riverine hyporheic zones at the regional scale.
From: Ammonium-derived nitrous oxide is a global source in streams
a Overview of the Baiyangdian riverine network and the sampling sites; b Spatiotemporal distribution of the potential rate of NH4+-derived and NO3--derived N2O production in the five streams (46–273 km length) of the Baiyangdian riverine network (n = 3 biologically independent samples). Data were presented as mean values ± SEM; c Spatiotemporal heterogeneity analyses of the potential rate and contribution of NH4+-derived and NO3−-derived pathways at the regional scale. P values were calculated with the two-tailed independent t-test (*p < 0.05, **p < 0.01 two-tailed; Except n = 44 and 56 independent experiments for upstream and downstream, respectively, n = 50 for other groups); d Potential rates and contributions of nitrifier nitrification (NN), nitrifier denitrification (ND), nitrification-coupled denitrification (NCD), and heterotrophic denitrification (HD) pathways in the sediments of the riverine hyporheic zones in the Tang River (n = 20 independent experiments). For each box chart, the horizontal line indicates the median, the box represents the 25th and 75th percentiles, and the whisker shows the range from the 5th to the 95th percentile. Bai River, B; Juma River, J; Cao River, C; Tang River, T; Zhulong River, Z; and Riparian zone, R; riverbed zone, O.
