Related Experiment Video
Updated: May 5, 2026

Understanding Dissolved Organic Matter Biogeochemistry Through In Situ Nutrient Manipulations in Stream Ecosystems
Published on: October 29, 2016
No nitrification in lakes below pH 3.
Christina Jeschke1, Carmen Falagán, Kay Knöller
1UFZ - Helmholtz Centre for Environmental Research , Department of Catchment Hydrology, Theodor-Lieser-Strasse 4, D-06120 Halle, Germany.
Nitrification, the process converting ammonium to nitrate, was measured in acidic and neutral mine pit lakes. This vital microbial process was only detected in neutral lakes, indicating acidity inhibits nitrification.
Area of Science:
- Environmental Science
- Microbiology
- Limnology
Background:
- Acid mine drainage (AMD) and acid rain elevate ammonium in lakes, impacting water quality.
- Microbial nitrification is assumed to be inhibited in acidic waters, but direct measurements are lacking.
Purpose of the Study:
- To directly measure nitrification rates in acidic and neutral mine pit lakes.
- To determine the impact of pH on ammonium oxidation in lake ecosystems.
Main Methods:
- Utilized (15)NH4Cl isotope tracer addition to quantify nitrification.
- Analyzed water column, biofilms, and sediment layers for nitrogen conversion.
- Employed stable isotope analysis (18O) to confirm nitrification pathways.
Main Results:
- Nitrification was detected exclusively in neutral mine pit lakes.
- No ammonium conversion to nitrate was observed in acidic lakes.
- High ammonium concentrations (>10 mg NH4-N L(-1)) were found only in lakes with pH < 3.
Conclusions:
- Acidity significantly inhibits microbial nitrification in lake environments.
- The lower pH limit for nitrification in lakes is approximately 3.
- Findings clarify ammonium fate in acidic aquatic ecosystems affected by AMD and acid rain.
More Related Videos
Related Concept Videos
The Nitrogen Cycle
The Phosphorus Cycle
Overview of Nitrogen Metabolism
The largest pool of nitrogen available in the terrestrial ecosystem is gaseous nitrogen (N2) from the air, but this...
Metabolism of Chemolithotrophs
Inorganic Nitrogen Assimilation
Freshwater Microbial Ecology

