Environmental Engineering Reference
In-Depth Information
lnC
a
,1
(
t
)
=−
×
t
−
constant
(11.37)
The absorption rate is calculated from data measured during the exposure period,
as follows:
dm
a
,1
(
t
)
dt
+
×
m
a
,1
(
t
)
f
abs
,
a
=
(11.38)
I
a
(
t
)
or, if M
a,1
can be assumed to be constant:
dC
a
,1
(
t
)
dt
C
a
,1
(
t
)
+
×
×
M
a
,1
f
abs
,
a
=
(11.39)
I
a
(
t
)
λ
a
can be identified at the steady-state with Eq. (
11.32
)orby
measuring the mean concentration in the excreted tissue from
t
1
to
t
2
, after the end
of the exposure period, by using the following equations:
When
I
a
(
t
)
If
λ
a
=
0,
k
a
and
=
0, the development of the concentration in excreted tissue is as
follows:
dm
a
,2
dt
=
k
a
×
m
a
,1
(11.40)
k
a
k
a
+
λ
a
×
e
−
(
k
a
+
λ
a
)
×
(
t
−
T
)
=−
×
+
m
a
,2
(
t
)
m
a
,1
(
T
)
constant
(11.41)
in which
T
=
last day of exposure [d]
e
−
(
k
a
+
λ
a
)
×
(
t
1
−
T
)
e
−
(
k
a
+
λ
a
)
×
(
t
2
−
T
)
(11.42)
k
a
k
a
+
λ
a
×
m
a
,2
(
t
2
)
−
m
a
,2
(
t
1
)
=
m
a
,1
(
T
)
×
−
and if
M
a
,2
is constant:
M
a
,2
(
m
a
,2
(
t
2
)
−
m
a
,2
(
t
1
)
=
t
2
−
t
1
)
×
C
a
,2
t
1
→
(11.43)
t
2
in which
C
a
,2
t
1
→
average concentration in the excreted tissue from
t
1
to
t
2
t
2
M
j
λ
a
×
a
,2
(
t
2
−
t
1
)
×
C
a
,2
t
1
→
t
2
k
a
=
×
e
−
(
k
a
+
λ
a
)
×
(
t
1
−
T
)
e
−
(
k
a
+
λ
a
)
×
(
t
2
−
T
)
−
M
a
,2
(
m
a
,1
(
T
)
−
t
2
−
t
1
)
×
C
a
,2
t
1
→
t
2
(11.44)
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