Application of Ultrasonic Extraction to Measure Particulate Bioavailable Phosphorus in Lake Sediment

Nutrient measurement to control eutrophication in closed water environment is an approach toward sustainable development. Accurate as well as fast measurements are vital to determine agricultural land use, watershed construction or urban planning. The nutrients, mainly nitrogen and phosphorus, contributing to eutrophication are clarified as rather their bioavailability to algal growth than the current standards of their total concentrations. In particular, the bioavailable phosphorus has been shown significantly partial and more related to fluctuations of a particulate fraction. Algal bioassays have been ideal to determine the bioavailability but it takes time and advanced labor. Therefore, extraction and chemical analyses have been suggested for routine measurements. This research examined an ultrasonic bath to fasten the extraction of particulate bioavailable phosphorus in certified lake sediment. The bioavailability of extracted phosphorus was confirmed by algal bioassays using Microcystis aeruginosa, common blue-green algae in Japan’s fresh water. The algal growth potential in bioassays illustrated ultrasonic extraction was useful for the measurement of bioavailable phosphorus in lake sediment.