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Is in-stream processing an important control on spatial changes in carbon fluxes in headwater catchments?
J J Dawson1, C Bakewell, M F Billett
1Department of Plant & Soil Science, University of Aberdeen, UK. j.j.dawson@abdn.ac.uk
The Science of the Total Environment
|March 3, 2001
Summary
This study reveals how dissolved organic carbon (DOC) and dissolved inorganic carbon (DIC) change in headwater streams. In-stream processing and CO2 outgassing significantly impact carbon fluxes in peat-rich upland catchments.
Area of Science:
- Environmental Science
- Hydrology
- Biogeochemistry
Background:
- Headwater streams are crucial in regional carbon budgets, yet their small-scale spatial dynamics are not fully understood.
- Upland catchments with organic-rich soils present unique challenges for carbon cycling research.
Purpose of the Study:
- To quantify spatial variations in dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), and carbon dioxide (CO2) fluxes within a Scottish headwater stream.
- To determine the influence of in-stream processes and atmospheric exchange on carbon dynamics over a 2.7 km stretch.
Main Methods:
- Measured concentrations of DOC, DIC, and CO2 at various points along the stream.
- Utilized chloride as a conservative tracer to account for diffuse water inputs.
- Calculated instantaneous carbon fluxes and estimated gains/losses within the stream system.
Main Results:
- DOC concentrations peaked in peat-dominated areas before declining downstream.
- DIC and CO2 concentrations showed significant increases through peat areas, influenced by tributary inputs, before declining.
- Substantial removal of DOC (11.6-17.6%) and significant losses of DIC (over nine times the outlet flux) occurred in-stream, alongside CO2 outgassing.
Conclusions:
- In-stream processing of DOC and DIC, along with CO2 outgassing, are key drivers of spatial carbon flux variability in these upland streams.
- Headwater streams in organic-rich catchments play a significant role in processing and transporting carbon.
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