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Mobilization of optically invisible dissolved organic matter (iDOM) in response to rainstorm events in a tropical forest headwater river.

Research output: Contribution to journalJournal article


  • Ryan Pereira
  • C. Isabella Bovolo
  • Robert G. M. Spencer
  • Peter J. Hernes
  • Edward Tipping
  • Andrea Vieth-Hillebrand
  • Nikolai Pedentchouk
  • Nick A. Chappell
  • Geoff Parkin
  • Thomas Wagner
<mark>Journal publication date</mark>28/02/2014
<mark>Journal</mark>Geophysical Research Letters
Issue number4
Number of pages7
Pages (from-to)1202–1208
<mark>Original language</mark>English


This study emphasizes the importance of rainstorm events in mobilizing carbon at the soil-stream interface from tropical rainforests. Half-hourly geochemical/isotopic records over a 13.5 h period from a 20 km2 tropical rainforest headwater in Guyana show an order of magnitude increase in dissolved organic carbon (DOC) concentration in less than 30 mins (10.6–114 mg/L). The composition of DOC varies significantly and includes optically invisible dissolved organic matter (iDOM) that accounts for a large proportion (4–89%) of the total DOC, quantified using size exclusion chromatography (SEC). SEC suggests that iDOM is comprised of low molecular weight organic moieties, which are likely sourced from fresh leaf litter and/or topsoil, as shown in soils from the surrounding environment. Although poorly constrained at present, the presence of iDOM further downstream during the wet season suggests that this organic matter fraction may represent an unquantified source of riverine CO2 outgassing in tropical headwaters, requiring further consideration.

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