Environmental Engineering Reference
In-Depth Information
The Freundlich-type equation can be extended, using soil parameters such as soil
pH and soil organic matter (S) (Adams et al.
2004
; Efroymson et al.
2001
; Hough
et al.
2003
; Plette et al.
1999
).
log [
M
plant
]
=
a
+
blog[
M
soil
]
+
c[
pH
]
+
dlog[
S
]
(8.3)
Efroymson et al. (
2001
) have shown that incorporation of soil pH improved the
model for cadmium, mercury, selenium and zinc. Incorporation of other factors such
as CEC, total metal concentrations in soil and extractable concentrations in soil
using Freundlich-type equations has been reported for various vegetables and met-
als (Wang et al.
2004
). In most cases the use of soil parameters, like pH, organic
matter, CEC or texture, improves the model performance compared to those based
on extractable or total concentrations only. For example in Fig.
8.8
and in Table
8.11
0.6
0.6
a
b
exp. fields
veg. gard.
liming exp.
farms
exp fields
veg. garden
liming exp.
farms
0.5
0.5
0.4
0.4
0.3
0.3
0.2
0.2
0.1
0.1
0
0
0
1
2
3
4
5
6
7
8
Soil Cd concentration (mg kg
-1
)
Soil pH (CaCl
2
)
0.8
1.2
c
d
exp. fields
veg. gard.
liming exp.
farms
95% confidence
0.7
1
0.6
0.8
0.5
0.4
0.6
0.3
0.4
0.2
0.2
0.1
0
0
0
0.2
0.4
0.6
4
4.5
5
5.5
.5
6
plant tissue Cd content (mg.kg
-1
fw)
pH
Fig. 8.8
Concentrations of cadmium in leek (
Allium ampeloprasum
L.) as a function of soil cad-
mium concentration (0.43 M HNO
3
extraction) (
a
), as a function of soil pH (
b
), predicted versus
measurements (
c
), and predicted soil concentrations (model No. 4 in Table
8.11
) as a function of
pH where the limit value for cadmium in leek is exceeded (
d
). Results are from several studies
near the Dutch zinc smelter in Budel: experimental fields, vegetable gardens, liming experiments
and farms. The dotted line is the European limit value for cadmium in leek
Search WWH ::
Custom Search