Figure 5.24 - Trends in the phosphorus concentration of seven European lakes (a and b different scales)

Sources: Walensee, Zürichsee and Bodensee after Stabel, 1991; Mondsee after Dokulil and Jagsch, 1992; Vänern after Olsson, 1991; Lac Léman after Lang, 1991; Lake Lugano after Barbieri and Mosello, 1992