Agriculture Reference
In-Depth Information
Zn
Cr
Cu
Ni
Med.
Max.
Med.
Max.
Med.
Max.
Med.
Max.
Before phytoremediation
EXP
inh
5.9×10
−6
1.1×10
−5
1.4×10
−6
3.5×10
−6
1.5×10
−6
2.1×10
−6
3.7×10
−6
7.0×10
−6
EXP
ing
2.7×10
−4
5.2×10
−4
6.5×10
−5
1.6×10
−4
7.1×10
−5
9.6×10
−5
1.7×10
−4
3.2×10
−4
EXP
abs
4.7×10
−5
8.9×10
−5
1.1×10
−5
2.8×10
−5
1.2×10
−5
1.6×10
−5
3.0×10
−5
5.6×10
−5
HQ
1.0×10
−3
2.0×10
−3
2.5×10
−2
6.2×10
−2
3.0×10
−3
4.1×10
−3
9.8×10
−3
1.9×10
−2
After phytoremediation
EXP
inh
5.8×10
-6
1.1×10
-6
1.4×10
-6
3.5×10
-6
1.5×10
-6
2.0×10
-6
3.7×10
-6
7.0×10
-6
EXP
ing
2.6×10
-4
5.1×10
-4
6.4×10
-5
1.6×10
-4
7.0×10
-5
9.5×10
-5
1.7×10
-4
3.2×10
-4
EXP
abs
4.5×10
-5
8.8×10
-5
1.1×10
-5
2.8×10
-5
1.2×10
-5
1.6×10
-5
2.9×10
-5
5.5×10
-5
HQ
1.0×10
-3
1.9×10
-3
2.4×10
-2
6.1×10
-2
2.9×10
-3
4.0×10
-3
9.7×10
-3
1.8×10
-2
Med.: median value; Max.: maximum value
Table 5. The hazard quotient (HQ) and the exposure risk of the three pathways before and
after phytoremediation.
Cr
Ni
Med.
Max.
Med.
Max.
Before phytoremediation
EXP
inh
(mg kg
-1
day
-1
)
2.1×10
−8
5.1×10
−8
5.3×10
−8
1.0×10
−7
TR
7.0×10
−7
1.8×10
−6
3.7×10
−8
7.0×10
−8
After phytoremediation
EXP
inh
(mg kg
-1
day
-1
)
2.0×10
-8
5.0×10
-8
5.3×10
-8
1.0×10
-7
TR
6.9×10
-7
1.7×10
-6
3.7×10
-8
7.0×10
-8
Med.: median value; Max.: maximum value
Table 6. The exposure and carcinogenic risk before and after phytoremediation if only the
inhalation was considered.
5. Uptake characteristics of different rice varieties growing in Cd-
contaminated soils
In 2005 and 2006, field studies were conducted in Taiwan to investigate the uptake
characteristics of rice varieties growing in 19 different paddy fields in three counties across
the western plains in Taiwan (Römkens et al., 2009). The studied fields were located at the
towns of Chang-hua (three fields), Ho-Mei (three fields), Lu-Kang (two fields), Hsin-Chu
(three fields), and Pa-Deh (eight fields) (Fig. 3). Twelve rice cultivars of Indica or Japonica
varieties were planted in each field with 5-9 replicates for each cultivar depends on the field
size. Samples of topsoil (0-25 cm) and rice plants at full maturity were collected together at
the same location in studied fields in May (harvest 1) and November (harvest 2) of the two
years. Total numbers of soil and rice plant samples in this study were both 3,198. The total
soil Cd concentration in studied fields ranged from 0.06 mg kg
-1
to as high as 27.8 mg kg
-1
,
the maximum level is about 6-fold higher than the SPCS (5 mg kg
-1
) enacted in Taiwan.
Around 27% of the studied field area was defined as Cd-contaminated soil according to the
SGWPR Act.
