Lake Bourget

May 29, 2002 - Year 2001. Transp mean ~ 6.2 m. Transp min ~ 3.3 m. Chloro ~ 7.7 mg.m-3. Page 4. Lake Bourget … Chlorophyll a &. Phytopk. story. 1969.
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S. Jacquet UMR CARRTEL

Lake Bourget

Workshop on water quality, Bruxelles, belgium

EC, Brussels, 29 May 2002

Lake Bourget … 180

Nutrient story N&P 1969 - 2002

-1

P-PO4 (µg.l )

150 120 90

Year 2001 PO4 ~ 18 µg.l-1 Ptot ~ 26 µg.l-1

60 30 0

1,0

1978 - 2002 -1

N-NO3 (mg.l )

0,8

0,6

0,4

0,2

0,0

Year 2001 NO3 ~ 0.46 mg.l-1 Ntot ~ 0.68 mg.l-1

Lake Bourget …

Transp. story

16

1981 - 2001 Transp (m)

12

8

4

0 16

May - June

Transp (m)

12

8

4

0

Year 2001 Transp mean ~ 6.2 m Transp min ~ 3.3 m Chloro ~ 7.7 mg.m-3

Chlorophyll a & Phytopk. story

Lake Bourget …

1969 - Fragilaria crotonensis - Aphanizomenom flos aquae First sign of eutrophisation

1995 - 1996 - Planktothrix rubescens - Achnantes catenata - Tribonema ambiguum Meso to eutrophic system

> 1996 - Planktothrix rubescens

Chl a (µg.l-1.year-1)

1982 - 1983 - Oscillatoria rubescens - Microcystis aeruginosa - Mougeotia gracillima - Tabellaria flocculosa Clear evidence of eutrophisation

10 9 8 7 6 5 4

1988 - 2001

Trophic status

Lake Bourget …

In summary for OECD 2001 Total P : 26 mg.m-3 Chlorophyll : 7.2 mg.m-3 Max chloro : 35.1 mg.m-3 Mean Secchi : 6.2 m Min Secchi : 3.3 m

M M E O O

Lake Bourget …

Source

Report on evolution of water quality in Lake Bourget (1995 – 1996) + Data base (S Jacquet)