KAZALCI OKOLJA

Key message
Neutral

In Europe, the number of lakes with low phosphorus content and greater transparency is increasing, as a result of measures taken to reduce pressures of to lakes. Similarly the improvement, compared to the situation in seventies, has been observed in Lake Bled as well. But in the last years "blooming" of phytoplankton in the lake appears with increasing frequency, with impact on worse transparency and indicating the increase in trophic status. Lake Bohinj is one of the oligotrophic, flow-through alpine lakes where the effects of man in the lake’s water basin, covering a sparsely populated mountain karst area, are relatively mild. In the artificial reservoirs, especially those in central and northeastern Slovenia, where agriculture is the main activity, the average content of phosphorus is significantly higher and transparency lower than in natural lakes, with no trend of improvement.



Charts

Figure VD07-1: Average (annual) concentration of the entire phosphorus load in selected lakes expressed in µg P/l
Sources:

Standardised Database for Water Quality Monitoring, Environmental Agency of the Republic of Slovenia, 2010

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Blejsko jezero Bohinjsko jezero Velenjsko jezero Šmartinsko jezero Slivniško jezero Perniško jezero Ledavsko jezero Gajševsko jezero Ptujsko jezero Klivnik
2007 micro g P/l 12.7 5.2 94 95 85 192 135 222 33.8 9.2
2008 micro g P/l 11.6 3.6 30.4 48.7 29.2 126.2 103.5 88.7 58.7 9.9
2009 micro g P/l 13.2 3.5 24.5 160.2 37.5 252.4 137.1 122 35.5 15
2010 micro g P/l 11.5 4.1 54.8 46.3 22.7 179.7 69.6 112 55.1 11.6
Mola Vogršček Družmirsko jezero
2007 micro g P/l 19.4 9.2
2008 micro g P/l 13.7 9.2
2009 micro g P/l 15.4 9.9
2010 micro g P/l 10.6 8.2 52
Figure VD07-2: Average transparency of selected lakes
Sources:

Standardised Database for Water Quality Monitoring, Environmental Agency of the Republic of Slovenia, 2005

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Blejsko jezero Bohinjsko jezero Velenjsko jezero Šmartinsko jezero Slivniško jezero Perniško jezero Ledavsko jezero Gajševsko jezero Ptujsko jezero Klivnik
2007 Secchi depth (m) 8.3 9.2 4.8 0.8 1.1 0.2 0.3 0.4 0.6 3.1
2008 Secchi depth (m) 6.6 9 4.6 1.1 1.3 0.5 0.5 0.5 0.7 3.3
2009 Secchi depth (m) 5 8.3 6.8 1.4 1.5 0.4 0.5 0.5 0.5 2.3
2010 Secchi depth (m) 4.5 8.5 6.1 1 1.2 0.4 0.5 0.5 1.2 3
Mola Vogršček Družmirsko jezero
2007 Secchi depth (m) 2.1 1.5
2008 Secchi depth (m) 2.4 3.1
2009 Secchi depth (m) 2 2.6
2010 Secchi depth (m) 3 2.6 3.2