Title: Management of Water Quality in Italian Lakes: the recovery of Lago Maggiore from eutrophication and
1Management of Water Quality in Italian Lakes
the recovery of Lago Maggiore from eutrophication
and Lago d Orta from acidification
- Riccardo de Bernardi and Alcide Calderoni
- C.N.R. Institute of Ecosystem Study Pallanza -
Italy
2TheRECOVERY of LAGO MAGGIORE from
EUTROPHICATION
3A satellite view of Lago Maggiore and Lago
dOrta
4LAGO MAGGIORE
-1
µg P l
40
Reactive Phosphorous
30
Total Phosphorous
20
1955
1960
1965
1970
1975
1980
1985
1990
1995
2000
2005
Annual trends of total and reactive phosphorous
average concentrations
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6LAGO MAGGIORE
7Lago Maggiore
50
1986
45
1989
1995
40
1999
35
30
number of species
25
20
15
10
5
0
JAN
FEB
MAR
APR
MAY
JUN
JUL
AUG
SEP
OCT
NOV
DEC
Seasonal evolution of the number of species in
Phytoplankton populations
8TheRECOVERYofLAGO DORTA from ACIDIFICATION
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10-1
mg N l
Lago d'Orta average values of ammoniacal
nitrogen
1,6
0 - 25 m
1,4
0 - 143 m
1,2
Liming period
liming
1,0
0,8
0,6
0,4
0,2
0,0
'88
'89
'90
'91
'92
'93
'94
'95
'96
'97
'98
'99
'00
'01
'02
11-1
µeq l
Lago dOrta Evolution of potential alkalinity
(Palk)
Prevision after Palk increase
observed values at spring overturn
12LAGO DORTA
-1
pH
mg N l
6,0
9,0
ammonium
nitrates
5,0
8,0
pH
4,0
7,0
3,0
6,0
2,0
5,0
1,0
4,0
0,0
3,0
1925
1935
1945
1955
1965
1975
1985
1995
2005
13LAGO DORTA
-1
µg l
140
120
100
80
60
Copper
40
Aluminium
Zinc
20
0
1950
1955
1960
1965
1970
1975
1980
1985
1990
1995
2000
141984
3
-3
cm
m
15
LAGO DORTA PHYTOPLANKTON BIOVOLUME
criptoficeae
10
cloroficeae
ultraplankton
5
1993
3
-3
cm
m
3
criptoficeae
diatomeae
cloroficeae
0
peridineae
2
gen
feb
mar
apr
may
jun
jul
aug
sep
oct
nov
dec
crisoficeae
cianoficeae
1989
3
-3
cm
m
ultraplankton
4
1
diatomeae
3
cloroficeae
crisoficeae
0
2
gen
feb
mar
apr
may
jun
jul
aug
sep
oct
nov
dec
ultraplankton
1
0
gen
feb
mar
apr
may
jun
aug
sep
oct
nov
dec
jul
15LAGO dORTA ZOOPLANKTON
1970
1975
1980
1985
1990
16LAGO dORTA FISH SPECIES
1926
1945
1985
1993
17EQUAZIONE DEL BILANCIO DI MASSA PER UNA SOSTANZA
CONSERVATIVA DISCIOLTA IN LAGO
ASSUNZIONI ED IPOTESI
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