Geomorphically mediated carbon dynamics of floodplain soils and implications for net effect of carbon erosion

The fate of organic carbon deposited in floodplain sediments is an important control on the magnitude and direction flux from anthropogenically accelerated erosion channelization riverine network. Globally, deposition rates mean residence time (MRT) within different geomorphic settings remains poorly constrained. We sampled soil profiles to 0.8 m depth two zones: active channel belt (ACB) lowland floodplain, under long-term pasture adjacent river Culm SW England, UK. evaluated sedimentation storage using fallout radionuclide 137Cs, particle size total analyses. Variation decomposition was assessed via empirical (soil aggregate size, density fractionation combined with natural abundance 13C analysis) modelling simulation (using RothC model catchment implications explored a evolution model). Sedimentation accumulation were 5-6 times greater ACB than floodplain. Carbon also varied setting. In cores, faster indicated by 13C-enrichment subsoils dominated mineral-associated carbon. Whereas, ACB, less processed 13C-depleted, light fraction macroaggregate-carbon throughout modelled 4-fold cores. Including MRT calculations increased overall 10%. major differences balance between inactive floodplains suggests relative extent these contrasting zones critical balance. Restoration projects could enhance maximising areas increasing complexity. This article protected copyright. All rights reserved.