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Updated: Aug 11, 2026
06:42
Measuring Phosphorus Release in Laboratory Microcosms for Water Quality Assessment
Published on: July 22, 2019
Particulate phosphorus bioavailability as a function of stream flow and land cover
Micaela E Ellison1, Michael T Brett
1Department of Civil and Environmental Engineering, University of Washington, Box 352700, Seattle, WA 98195, USA.
Water Research
|March 7, 2006
Summary
Bioavailability of phosphorus varies by land use, with urban streams showing high bioavailability during baseflows but declining during storms. Only a fraction of phosphorus transported during storms is biologically available, impacting eutrophication risk assessments.
Area of Science:
- Environmental Science
- Ecology
- Water Quality
Background:
- Estimating eutrophication risk using total phosphorus is limited because not all phosphorus forms are biologically available.
- Particulate phosphorus bioavailability is a critical factor influencing aquatic ecosystem health.
Purpose of the Study:
- To assess the bioavailability of particulate phosphorus in streams across different land cover types (forested, urban, agricultural, mixed).
- To determine how bioavailability varies between baseflow and stormflow conditions.
- To understand the implications for eutrophication risk management.
Main Methods:
- Sampling of 16 stream sites under base and stormflow conditions.
- Measurement of total suspended solids, various phosphorus fractions, and sediment particle size.
- Algal assays using Pseudokirchneriella subcapitata to determine percent bioavailable particulate phosphorus (%BAPP).
Main Results:
- %BAPP averaged 17% (forested), 26% (mixed), and 24% (agricultural), with no significant flow condition differences.
- %BAPP in urban streams was high (73%) during baseflows but decreased significantly (19%) during storms.
- Storm events drastically increased particulate phosphorus (614%) and total phosphorus (200%), but total bioavailable phosphorus increased less (72%) due to low bioavailability of storm-transported phosphorus.
Conclusions:
- Land cover significantly influences phosphorus bioavailability, with urban areas exhibiting unique baseflow characteristics.
- The low bioavailability of phosphorus during storm events is a key factor in managing eutrophication risk.
- Relying solely on total phosphorus concentrations can overestimate eutrophication potential, especially during high-flow events.
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