Nutrient status of the sediments in Lake Mulwala. I. Total phosphorus

Abstract

Chemical analyses are reported for sediment samples taken from Lake Mulwala, a man-made lake on the Murray River, downstream from the proposed Albury-Wodonga growth centre. The sediments are non-calcareous and high in clay content. Total phosphorus levels were found to be of the same order of magnitude as values reported for several eutrophic lakes in other countries. Statistical analysis of the data has allowed the calculation of a predictive model for total phosphorus levels in the lake sediments. Total phosphorus was found to be influenced by location within the lake, organic content of the sediments and water depth. On the basis of total phosphorus levels, Lake Mulwala can be divided into two regions-an upper region influenced by the two input rivers, which has lower levels of total phosphorus, and a lower region with higher levels of sediment phosphorus. It appears that about 50% of this total phosphorus is potentially available for exchange with the water column.