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Buffering processes in a boreal dissolved organic carbon-rich stream during experimental acidification
1Department of Forest Ecology, Swedish University of Agricultural Sciences, 901 83 Umeå, Sweden. hruska@cgu.cz
Environmental Pollution (Barking, Essex : 1987)
|April 20, 2004
Summary
Organic acids significantly buffer surface water acidity, with protonation of organic acids neutralizing 60% of added acid in a Swedish stream. This buffering is crucial in the environmentally important pH range of 4.4 to 5.3.
Area of Science:
- Environmental Chemistry
- Hydrology
- Ecology
Background:
- Surface water acidity is influenced by organic acids.
- Anthropogenic acidification poses a threat to aquatic ecosystems.
- Understanding buffering mechanisms is vital for water resource management.
Purpose of the Study:
- To investigate the role of organic acids in buffering surface water acidity.
- To quantify the buffering capacity of organic acids during experimental acidification.
- To compare organic acid dissociation models with field data.
Main Methods:
- A field experiment was conducted on a total organic carbon (TOC)-rich stream in northern Sweden.
- Sulfuric acid (H2SO4) was added to simulate anthropogenic acidification.
- Two models of organic acid dissociation were fitted to experimental results.
Main Results:
- Approximately 60% of added H+ was buffered by organic acid protonation.
- Base cations contributed 20% to buffering, with 20% remaining unbuffered.
- TOC concentrations and carboxylic group density remained stable.
- Organic acid dissociation model parameters differed from previous studies.
Conclusions:
- Organic acids play a substantial role in buffering anthropogenic acidification in TOC-rich streams.
- The buffering effect of TOC is significant between pH 4.4 and 5.3.
- Existing models may require regional parameter adjustments for accurate predictions.