Surface micro-topography causes hot spots of biogeochemical activity in wetland systems: A virtual modeling experiment
Article first published online: 10 OCT 2012
©2012. American Geophysical Union. All Rights Reserved.
Journal of Geophysical Research: Biogeosciences (2005–2012)
Volume 117, Issue G4, December 2012
How to Cite
2012), Surface micro-topography causes hot spots of biogeochemical activity in wetland systems: A virtual modeling experiment, J. Geophys. Res., 117, G00N12, doi:10.1029/2012JG002012., , , and (
- Issue published online: 10 OCT 2012
- Article first published online: 10 OCT 2012
- Manuscript Accepted: 24 AUG 2012
- Manuscript Revised: 16 AUG 2012
- Manuscript Received: 2 MAR 2012
- biogeochemical turnover;
- hot spots;
 Wetlands provide important ecohydrological services by regulating fluxes of nutrients and pollutants to receiving waters, which can in turn mitigate adverse effects on water quality. Turnover of redox-sensitive solutes in wetlands has been shown to take place in distinct spatial and temporal patterns, commonly referred to as hot spots and hot moments. Despite the importance of such patterns for solute fluxes the mechanistic understanding of their formation is still weak and their existence is often explained by variations in soil properties and diffusive transport only. Here we show that surface micro-topography in wetlands can cause the formation of biogeochemical hot spots solely by the advective redistribution of infiltrating water as a result of complex subsurface flow patterns. Surface and subsurface flows are simulated for an idealized section of a riparian wetland using a fully integrated numerical code for coupled surface-subsurface systems. Biogeochemical processes and transport along advective subsurface flow paths are simulated kinetically using the biogeochemical code PHREEQC. Distinct patterns of biogeochemical activity (expressed as reaction rates) develop in response to micro-topography induced subsurface flow patterns. Simulated vertical pore water profiles for various redox-sensitive species resemble profiles observed in the field. This mechanistic explanation of hot spot formation complements the more static explanations that relate hot spots solely to spatial variability in soil characteristics and can account for spatial as well as temporal variability of biogeochemical activity, which is needed to assess future changes in the biogeochemical turnover of wetland systems.