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where the coef
cient w
p
(cm/day) describes the process of gravitational sedimen-
tation and is estimated at
8
<
50
for
0
z
z
b
;
w
p
¼
10
for
z
b
\
z
z
l
;
\
:
30
for
z
z
l
Bacteria feed on detritus and dissolved organic matter emitted by phytoplankton.
The allochthonous dissolved organic matter is neglected. In the Eq. (
4.36
)an
approximation is considered:
T
p
þ
T
b
þ
T
Z
þ
T
r
þ
T
D
¼ 0
:
3R
p
:
;
;
ʼ
b
= 0.01,
:
75 1
10
f
R
p
¼ 3b 1
10
f
It
is also assumed that
t
b
¼ 0
f
¼
0
3R
p
:
A limitation that during a 24 h bacterioplankton can consume not more than
10 % of all detritus located in the same water layer is established.
On these assumptions, the Eq. (
4.35
) is written as:
:
2d
0
:
05
X
i
2x
0
2
n
@
z
2
@
n
=@
t ¼
0
:
1R
p
þ
0
:
1d
þ
0
:
t
i
B
i
þ
k
2
@
þ
V
z
@
n
=@
z
;
where
ˉ
0
={p, b, Z
j
(j =1
−
7)}, B
i
is the biomass of the i-th element.
cients k
2
(cm
2
/day) and V
z
(cm/day) are assumed to be:
The coef
8
<
:
8
<
:
5
for
0
z
z
b
;
200
for
0
z
z
b
;
V
z
¼
0
:
1
for
z
b
\
z
z
l
;
k
2
¼
50
for
z
b
\
z
z
l
;
\
\
1
for
z
z
l
;
150
for
z
z
l
:
The formula (
4.18
) for the case considered is simpli
ed:
Þ
¼ E
0
10
a
z
n
E
ð
u; k;
z
n
;
t
;
where z
n
is the depth of the nth layer (m);
001
X
n
a
¼ 0
:
01
þ
0
:
½
pz
k
;
ðÞþ
dz
k
;
ðÞ
=
z
n
k¼0
A marked suppression of phytoplankton is observed at E > 100 cal/cm
2
/day.
Hence, the formula (
4.20
) is re-written:
041E
10
0
:
25 1
E
=
E
max
½
K
T
¼ 0
:
;
70 cal/cm
2
/day.
where E
max
≈
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