An analysis of the total phosphorus cycle in some temperate lakes: the response to enrichment

Abstract

SUMMARY Total phosphorus (TP) cycles were examined in seventeen lakes from the Scottish lowlands and Northern Ireland, which varied in annual mean TP from 17 to 192 μg Pl‐1. It is clear from the data that the annual range of TP concentrations increases as the annual maximum TP increases. Although the annual minimum TP increases somewhat with increasing annual maxima, even enriched lakes show a pronounced TP minimum. As a result, the annual maximum values are highly correlated with the ranges and means, but less so with the annual minima. The data are discussed in relation to a conceptual sine wave model and it is suggested that enrichment modulates the amplitude of the sine wave. Mechanisms conditioning the maximum and minimum values are reviewed.