Agriculture Reference
In-Depth Information
from Cd-contaminated fields may be safer for consumers than brown rice. However,
Moriyama et al. (2003) reported that Cd concentration in six Japonica rice cultivars reduced
only 3% in average after milling process. A study using
in-situ
synchrotron X-ray
fluorescence to identify Cd distribution in brown rice produced from Bangladesh, China,
and U.S. also showed that Cd is evenly distributed in brown rice (Meharg et al., 2008). The
inconsistent findings among these studies may be caused by errors from rice polishing
process or inherent differences of Cd distribution in rice grain among rice cultivars. More
careful studies are required to clarify the inconsistent results.
Harvested from slightly Cd-contaminated fields in May
Harvested from seriously Cd-contaminated fields in May
1.0
10
0.8
8
0.6
6
0.4
4
0.2
2
0.0
0
0.00
0.05
0.10
0.15
0.20
0.0
0.5
1.0
1.5
2.0
2.5
CaCl
2
extractable Cd concentration in soil (mg kg
-1
)
CaCl
2
extractable Cd concentration in soil (mg kg
-1
)
Harvested from slightly Cd-contaminated fields in Nov.
Harvested from seriously Cd-contaminated fields in Nov.
1.8
18
1.6
16
1.4
14
1.2
12
1.0
10
0.8
8
0.6
6
0.4
4
0.2
2
0.0
0
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
CaCl
2
extractable Cd concentration in soil (mg kg
-1
)
CaCl
2
extractable Cd concentration in soil (mg kg
-1
)
Fig. 4. The relationship between CaCl
2
extractable Cd concentration in soil and Cd
concentration in brown rice (
‧
: Japonica species,
。
: Indica species) harvested in May and
November.
6. Various Cd uptake models were used to efficiently predict their
accumulation
Total Cd concentration in soil is not a reliable index to determine whether rice grain is safe
for consumers. Rice varieties and soil characteristics such as soil pH, Eh (redox potential),
CEC, texture, and SOM are important factors affecting Cd concentration in rice grain. To
determine whether a rice-growing field can produce safe rice grains with Cd levels lower
