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Updated: Jul 31, 2025
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Understanding Dissolved Organic Matter Biogeochemistry Through In Situ Nutrient Manipulations in Stream Ecosystems
Published on: October 29, 2016
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Dissolved organic matter transformations in a freshwater rivermouth
Nolan J T Pearce1, James H Larson2, Mary Anne Evans3
1Department of Biology, Trent University, Peterborough, ON Canada.
Biogeochemistry
|May 8, 2023
Summary
The Fox rivermouth acts as a carbon sink, processing dissolved organic carbon (DOC) and transforming its composition. This river mouth ecosystem significantly alters dissolved organic matter before it enters Lake Michigan.
Area of Science:
- Environmental Chemistry
- Aquatic Ecology
- Biogeochemistry
Background:
- Rivermouths are critical transition zones influencing aquatic ecosystems.
- Understanding carbon cycling in these areas is vital for aquatic continuum health.
- Limited research exists on carbon budgets and processing in freshwater rivermouths.
Purpose of the Study:
- To measure carbon processing and assess the carbon budget of the Fox rivermouth.
- To investigate changes in dissolved organic matter (DOM) composition during transit.
- To identify factors controlling DOM processing in rivermouth ecosystems.
Main Methods:
- Incubation experiments of water column (light and dark) and sediments.
- Measurements of dissolved organic carbon (DOC) and DOM.
- Analysis of DOM optical properties and composition.
Main Results:
- The Fox rivermouth functions as a net sink for DOC, with water column mineralization exceeding sediment release.
- DOM composition shifted, showing decreased terrestrial humic-like and fulvic-like matter and increased microbial components.
- Higher total dissolved phosphorus correlated with consumption of specific DOM types but not bulk DOC.
Conclusions:
- The Fox rivermouth significantly transforms DOM, impacting the quality of organic matter entering Lake Michigan.
- Water column processes and other environmental factors play a role in DOM processing.
- Rivermouth ecosystems are key sites for biogeochemical transformations in aquatic systems.
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