b.
a.
1900
1950
2000
15
10
5
0
Nitrate concentration, mgN/l
Oligocene
Eocene
Chalk
0
5
10
15
20
25
30
1900
1950
2000
nitrate concentration, mgN/l
Traconne
St Brice
Vulaines
< 2
Nitrate concentration
in outcropping aquifer
formations, mgN/l
2 - 5
c.
0 20 40
5 - 8.5
8.5 - 11
> 11
areas of small aquifers not
taken into account in the
model
2010
80
120
160
Km
Fig. 10 (a) Long-term record of nitrate contamination in some springs in the Seine basin (springs
of the Petite Traconne, Saint Brice and Vulaines, Brie limestone formation). (b) Long-term
simulation of mean nitrate contamination in the major aquifer units of the Seine basin. (c) Map of
2010 level of nitrate contamination of sub-surface aquifer systems around the Seine watershed as
calculated by the STICS-MODCOU modelling chain [13]
106
G. Billen et al.