Effect of intermittency on N spatial variability in an arid Mediterranean stream

AbstractWe compared spatial patterns of N (NO3−-N and NH4+-N) and Cl− variability in 2 reaches with different hydrological regimes (permanent vs intermittent) of a typical Mediterranean semiarid stream under different hydrological conditions (baseflow, high flow, and drought). We hypothesized that stream-flow intermittency would affect N spatial variability. We expected higher spatial variability of solute concentrations in intermittent reaches than in permanent reaches because local environmental conditions (advection, water residence time, temperature, biotic properties, sediment–water interactions, or environment redox condition) change through space as flow discharge does. We expected spatial heterogeneity of solute concentrations to change more through seasons, as do stream hydrological conditions (high flood periods and drought), in the intermittent than in the permanent reach. We also expected seasonal variability to be higher in the intermittent than in the permanent reach. We used the coefficient...