RESUMO
For improving the management of watershed eutrophication, methods for measuring bioavailable phosphorus (BAP) are more important than measurements of total phosphorus (TP). BAP in particulate form (P-BAP) is an important substance that promotes eutrophication, especially during rainy seasons. Only a portion of particulate phosphorus (PP) is taken up by algae that contribute to eutrophication. Erosion and runoff associated with rainfall transport PP bound to sediments and soil particles to surface waters, thus increasing PP concentration. This research evaluated an extraction method using an ultrasonic washing machine for extraction time and frequency. Extraction at a frequency of 28-45 kHz and an extraction time of 1 min resulted in extracted P concentrations almost the same as concentrations extracted using conventional methods. This new method requires less time and is more efficient than conventional methods because it extracts P from multiple samples in a single step. Results indicate that extraction using an ultrasonic washing machine is a promising method for rapidly obtaining BAP from sediments and soil particles.