Potential Mobility of Phosphorus in Different Types of Lake Sediment

The fractional composition and potential mobility of sediment phosphorus was investigated in a number of Swedish lakes with different characteristics. Differences between sediments regarding P release patterns in laboratory experiments with varying pH and redox conditions could largely be explained by differences in the fractional composition of the sedimentary P. Sediments from sewage‐loaded lakes contained considerably more loosely adsorbed P than unpolluted lakes. P release was redox‐sensitive and strongly favoured by high pH values in sediments with a high content of aluminium and iron‐bound P. Other sediments released primarily organic and loosely adsorbed P, and in such cases less P was released and redox and pH conditions had less effect. Comparisons with P release rates determined by mass balance calculations were made.