Organic carbon and nitrogen dynamics during a peatland storm event: How dissolved combined amino acids reveal the spatial and temporal separation of organic molecules

Ewen Silvester, Terry Karis, Anne Yusuf, John Pengelly, Samantha Grover, Gavin N. Rees

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

The export of fixed carbon from peatlands is likely important in driving freshwater ecosystem productivity in head water streams. Here we studied the stream composition from three peatlands, and the sub-catchment containing these peatlands, in response to a natural storm event. We investigated the dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) mobilised by this event as well as the dissolved combined amino acids (DCAAs; proteins, peptides and free AAs) component of the DOC/DON. The storm pulse was characterised by a strong DOC/DON/DCAA pulse reflecting the mobilisation of materials from the peat profile. Through the storm cycle a transient increase in the C:N ratio of the DOC was observed (ranging over 20 – 50 across the four sites), likely reflecting the mobilisation of less decomposed material from higher in the peat soil profile. By comparing the DCAA and DON dynamics we show that a DCAA-rich component (fast-DCAA) is mobilised earlier in the storm cycle, likely reflecting a higher mobility in the peat soil. Similarly, comparison of the DCAA and DOC dynamics suggests that at least part of the DOC is mobilised more rapidly than fast-DCAA (fast-DOC). While we may not expect the composition of a storm pulse to be uniform through the cycle, this study shows that within the DOC and DON pools there is spatial and temporal separation of molecular groups. Proteins (in principal) represent both highly bioavailable N-sources as well as potential biological trigger molecules, so our work shows that these compounds are more dominant in the early part (rising limb) of the storm pulse. This understanding of the changing composition of DOC through a storm peak also provides greater insight into the concentration-discharge (C-Q) response of peatlands; our work shows that the activation of water paths higher in the peat profile at high flows leads to the mobilisation of different pools of DOC such that the molecular characteristics of DOC change through the storm cycle.

Original languageEnglish
Article number126191
Pages (from-to)1-10
Number of pages10
JournalJournal of Hydrology
Volume597
Early online date11 Mar 2021
DOIs
Publication statusPublished - Jun 2021

Fingerprint

Dive into the research topics of 'Organic carbon and nitrogen dynamics during a peatland storm event: How dissolved combined amino acids reveal the spatial and temporal separation of organic molecules'. Together they form a unique fingerprint.

Cite this