Phosphorus Speciation of Sediments of a Mesoeutrophic Lake in Quebec, Canada

Nutrients enter into lakes through point and non-point sources are finally settled in bottom sediments where they accumulate and eventually release back into the overlaying water. Sediment phosphorus release is one of the main reasons for eutrophication in many shallow lakes around the world. This present study examines sediment samples collected from Lake Johanne, a shallow, meso-eutrophic lake, and its neighboring wetland, to which the lake inlet is opened, for sediment phosphorus concentration and its speciation to understand the potential of sediment phosphorus to release into the lake water. Speciation of the sediment phosphorus was performed according to the SMT sequential extraction technique. The sequential extraction technique allowed extraction and quantification of different forms of phosphorus in the sediment as follows: (i) non apatite inorganic phosphorus (ii) apatite inorganic phosphorus, (iii) organic phosphorus and total phosphorus. The lake sediment and water quality were also monitored in terms of heavy metal concentrations.