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Comparison of several methods for BAP measurement
J Nakajima1, Y Murata, M Sakamoto
1Department of Environmental Systems Engineering, Faculty of Science and Engineering, Ritsumeikan Univ., 1-1-1 Nojihigashi, Kusatsu, Shiga 525-8577, Japan. jnakajim@nisiq.net
Summary
Estimating bioavailable phosphorus (BAP) in suspended solids is crucial for water quality management. A new method, biologically measured BAP (B-BAP), offers rapid and direct measurement, comparable to highly bioavailable phosphorus (HBAP).
Area of Science:
- Environmental Chemistry
- Water Quality Management
- Eutrophication Studies
Background:
- Accurate estimation of bioavailable phosphorus (BAP) in suspended solids (SS) is critical for managing water quality in lakes and estuaries.
- Traditional methods like the AGP test or 0.1 mol L⁻¹ NaOH extraction (C-BAP) are widely used but may not fully capture phosphorus bioavailability.
- Highly bioavailable phosphorus (HBAP) was introduced as a more soluble fraction, but a direct biological measurement is needed.
Purpose of the Study:
- To introduce and validate a new method for measuring biologically measured BAP (B-BAP) using bacterial respiration activity.
- To compare B-BAP with existing methods, including HBAP and C-BAP, for assessing phosphorus bioavailability in river SS.
- To investigate the characteristics of SS and phosphorus bioavailability in urban versus agricultural river systems.
Main Methods:
- B-BAP was estimated using oxygen uptake rate (OUR) measured by a respiratory meter for BOD analysis.
- Successive extraction methods were used to determine HBAP (HCl and NaOH extraction) and C-BAP (NaOH extraction).
- Phosphorus fractions in river SS, paddy soil, and activated sludge were analyzed and compared.
Main Results:
- B-BAP provides a rapid and direct measure of phosphorus bioavailability in SS.
- Urban river SS showed higher percentages of HBAP and B-BAP, indicating a greater proportion of easily bioavailable phosphorus.
- Rivers in agricultural areas had higher C-BAP content, with SS primarily composed of inorganic particles (clay, silt, sand).
Conclusions:
- B-BAP is a valuable tool for assessing phosphorus bioavailability, offering direct biological insight.
- HBAP serves as a suitable and rapid index for easily bioavailable phosphorus in SS, showing strong correlation with B-BAP.
- The composition of SS differs significantly between urban and agricultural rivers, impacting phosphorus bioavailability and water quality management strategies.