ORIGINAL PAPER Phosphorus speciation in Myall Lake sediment, NSW, Australia Daniel Abel Shilla Æ Takashi Asaeda Æ Martin Kalibbala Received: 9 May 2007 / Accepted: 26 February 2008 / Published online: 18 March 2008 Ó Springer Science+Business Media B.V. 2008 Abstract The amount of phosphorus and its fractions in the sediment of Lake Myall, NSW, Australia, was assessed using a sequential extraction technique. Five sedimentary phosphorus reservoirs were measured, namely loosely sorbed phosphorus (NH 4 Cl–P), iron associated phosphorus (BD–P), calcium bound phosphorus (HCl–P), metal oxide bound phosphorus (NaOH–P) and residual phospho- rus (organic and refractory P, Res-P). Samples were taken from the deep and shallow sites of the lake. During the analysis, the average concentrations of each fraction of phosphorus was calculated. The results depicted that the total phosphorus (TP) content and chemically extractable phosphorus in both fine and coarse sediment fractions from the deep sites of the lake were significantly higher than those of the shallow sites, except for HCl–P extracted from the fine sediment fraction. Sediment TP was also strongly and positively correlated to sediment Fe. The phosphorus in the sediment mainly consisted of BD–P and Res-P, while NH 4 Cl–P and HCl–P only contributed a minor part. The rank order of the different phosphorus extracts was similar for the two sites, namely Residual- P [ BD–P [ NaOH–P [ HCl–P [ NH 4 Cl–P. Keywords Myall Lake Á Phosphorus Á Sediment Á Sequential fractionation Introduction Sediment plays an important role in determining the concentration, distribution and fate of pollu- tants, and is known to act as a principal reservoir which accumulates and/or releases the pollutants (Søndergaard et al. 1996; Kleeberg and Kozenski 1997). Phosphorus is known to limit the growth of algae in lakes and can limit marine productivity (Fytianos and Kotzakioti 2005). Phosphorus usually enters aquatic systems in the particulate form. The dissolved form of phosphorus may become associ- ated with particles as they settle out of the water column, and sink to the bottom. Sedimentation is a major phosphorus sink in the epilimnion zone of lakes, transporting phosphorus to the hypolimnion and finally to the lake bottom. The long-term contribution of sediment bound phospho- rus in promoting eutrophication of freshwater can be effectively evaluated on the basis of different phos- phorus fractions instead of total phosphorus content, D. A. Shilla (&) Á T. Asaeda Á M. Kalibbala Department of Environmental Science and Human Engineering, Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama-shi, Saitama 338-8750, Japan e-mail: dshilla@yahoo.com 123 Wetlands Ecol Manage (2009) 17:85–91 DOI 10.1007/s11273-008-9087-5