9' 8' 7' 6' 5'
9' 10'
ss"
50" __ ~12
)
.
......-::::=:::13
.0
\
~~\~12 ""', I
11
4!
fRANCE
6"
5"
4'
2"
I"
r!
,"
4'
5"
7'
ff
100
200
JOO
40V
500
600 k. m
~--~!----~!~--~!----~!----~!~--~I
Fig. 10. Nitrate concentration in North Sea water during the winter. The figures refer to nitrogen
reported as nitrate in Ilmol/l; they must be multiplied by fourteen if the values in Ilg/l are wanted
(McIntyre and Johnson 1975)
1977, one finds about 5 times higher P04 -P concentrations, 1-5 Ilmol PII in recent
samples. One can conclude that silicium now is the limiting nutrient for diatom
plankton growth, and one can correlate this increase of phosphorus with the introduction of phosphate-containing detergents in the early sixties (Hickel et al. 1980).
18
9' 10'
ss"
50" __ ~12
)
.
......-::::=:::13
.0
\
~~\~12 ""', I
11
4!
fRANCE
6"
5"
4'
2"
I"
r!
,"
4'
5"
7'
ff
100
200
JOO
40V
500
600 k. m
~--~!----~!~--~!----~!----~!~--~I
Fig. 10. Nitrate concentration in North Sea water during the winter. The figures refer to nitrogen
reported as nitrate in Ilmol/l; they must be multiplied by fourteen if the values in Ilg/l are wanted
(McIntyre and Johnson 1975)
1977, one finds about 5 times higher P04 -P concentrations, 1-5 Ilmol PII in recent
samples. One can conclude that silicium now is the limiting nutrient for diatom
plankton growth, and one can correlate this increase of phosphorus with the introduction of phosphate-containing detergents in the early sixties (Hickel et al. 1980).
18