Journal of Geophysical Research: Biogeosciences
© 2013 American Geophysical Union
Impact Factor: 3.021
ISI Journal Citation Reports © Ranking: 2011: 21/170 (Geosciences Multidisciplinary)
Online ISSN: 2169-8961
Associated Title(s): Journal of Geophysical Research
Micro-topography creates biogeochemical hotspots in wetlands
Interventions in wetlands could improve water quality, as wetlands regulate not only nutrients such as nitrogen and sulfur but also pollutants in the waters that flow through them. Biological and chemical processes maintain conditions for redox reactions in the wetlands that control the concentration of certain solutes, including nutrients and pollutants. But such biogeochemical processes are not evenly distributed and often are localized in 'hot spots' or take place in bouts known as 'hot moments.' How these hot spots or hot moments arise remains poorly understood and is often explained by simply evoking variations in soil properties in the wetlands. Creating a virtual wetland with measurements acquired from several field campaigns, Frei et al. (2012) show that complex micro-scale variations in topography of the wetland surface can change flow patterns of infiltrating water in a way that localizes biogeochemical processes, creating hot spots and hot moments. For various redox-sensitive solute species, they simulated how concentrations of redox-sensitive solutes change in pore waters; their simulations resembled observations from the field. This mechanistic explanation of hot spot formation complements explanations that relate the occurrence of hot spots and hot moments solely to variations in soil properties and hence can account for spatial as well as temporal variations of biogeochemical activity. It will be useful for assessing future changes in the turnover rates of nutrients and pollutants in wetlands.