Determination of bioavailable phosphorus in water samples using bioassay methods

Area of Science:

• Environmental Science
• Limnology
• Analytical Chemistry

Background:

• Total phosphorus (TP) is key in freshwater eutrophication management.
• The bioavailable fraction of TP varies significantly, complicating regulatory efforts.
• Existing methods lack precision in quantifying bioavailable phosphorus fractions.

Purpose of the Study:

• To develop and validate an algal bioassay for quantifying bioavailable phosphorus (P).
• To fractionate bioavailable P from soluble reactive phosphorus (SRP), dissolved organic phosphorus (DOP), and particulate phosphorus (PP).
• To provide a tool for ranking and targeting P sources in aquatic ecosystems.

Main Methods:

• Adapted and expanded existing methods from the late 1970s and early 1980s.
• Developed a congruent method to fractionate particulate and soluble phosphorus into bioavailable and unavailable forms.
• Utilized phosphorus-starved algae cultures, specific sub-sampling schedules, and kinetic determinations.

Main Results:

• Successfully fractionated TP into bioavailable and unavailable components using algal bioassays.
• Demonstrated reproducibility through replication and phosphorus mass balance closure.
• Provided a quantitative method for assessing bioavailable phosphorus in effluents and tributaries.

Conclusions:

• The algal bioassay offers a reliable approach to determine bioavailable phosphorus fractions.
• This method enhances the management of cultural eutrophication by identifying key phosphorus sources.
• The technique facilitates quantitative ranking and targeted interventions for phosphorus control.