Agriculture Reference
In-Depth Information
due to the higher content of Cr in soil A.
Bulrush had better enrichment of
heavy metals than corn except Cd.
Table 2. Concentrations of heavy metals in root, stem, leaf and fruit of
corn and bulrush near the sampling site A (mg
·kg
-1
)
Heavy
metal
Corn
fruit
Corn
root
Corn
stem
Corn
leaf
Bulrush
root
Bulrush
stem
Bulrush
leaf
Pb
0.10
2.41
1.97
3.15
6.92
4.62
2.78
Cd
0.01
0.12
0.22
0.07
0.04
0.07
0.13
Cr
0.52
1.87
1.26
1.66
4.61
3.57
4.02
As
0.00
0.10
0.10
0.08
0.11
0.17
0.25
4.
T
HERMODYNAMICS OF
H
EAVY
M
ETALS
AND
O
RGANCHLORINE
P
ESTICIDES
A
DSORPTION
ON THE
T
WO
S
OILS
The adsorption thermodynamics experiment of Pb, Cd, Cr(VI) and As(V)
respectively was carried out for 24h with initial metal concentrations ranging
from 0.05 to 100 mg·L
-1
for Pb and Cd by dilution of 1000 mg·L
-1
Pb(NO
3
)
2
,
Cd(NO
3
)
2
·4H
2
O and 0.05 to 10 mg·L
-1
for Cr(VI) and As(V) by dilution of
1000 mg·L
-1
K
2
Cr
2
O
7
and Na
2
HAsO
4
·7H
2
O (all analytical grade reagent) stock
solution with distilled-deionized water (dd H
2
O). BHC and DDT adsorption
experiment respectively was also carried out for 24h with initial BHC and
DDT concentrations ranging from 1-50 µg·L
-1
. Soil samples were weighed
precisely and transferred into beakers and submerged in 500mL solution with
different pollutant concentrations. The suspensions were stirred continuously
with magnetic stirrers, maintaining pH value at 6.0 ± 0.1 by adding 1 mmol·L
-1
HNO
3
and 1 mmol·L
-1
NaOH. After 24h, the soil suspensions were centrifuged
for 30 min at 5000 rpm, and the supernatants were collected for measurement
of pollutant concentration. The concentrations of Pb and Cd in the
supernatants were measured using the flame atomic absorption method (AAS
700 equipped with GFAAS, Perkin Elmer, USA). Cr(VI) was measured by 1,
5-diphenyl carbazide spectrophotometric method [13] using a WFJ2-7200
Spectrophotometer (Unico Instruments Co., Ltd, Shanghai, China). As(V) was
determined
by
flow
injection
hydride
generation
atomic
absorption
