Agriculture Reference
In-Depth Information
3. Phytoremediation for Cr, Cu, Ni, and Zn-contaminated soils
Eight blocks (11 m by 4 m) located in central Taiwan (Fig. 2), which were relatively higher in
Cr (chromium), Cu (copper), Ni (nickel), and Zn (zinc) concentrations were used for
in-situ
selection experiment (Lai & Chen, 2009). After making a market survey, 33 plant species of
garden flower species (Table 2) were selected for this
in-situ
experiment and two seedlings
per plant species were planted in each of the eight blocks. The interval space between two
plants was controlled at about 50-70 cm to avoid interference. The concentration of Cu, Cr,
Ni, and Zn in the 33 plant species before planting was determined. We recorded the growth
condition of plants, whether toxic symptom occurred or not, two weeks after planting in the
site and they were harvested after planting for 33 days. After pretreatment, the Cu, Cr, Ni,
and Zn concentration in the digest solution of initial and harvested plants were determined.
After
in-situ
growing in the contaminated soils for two weeks, we observed withered and
yellow color in the leaves of Bougainvillea and some of them fell off. The flowers of
Cockscomb were damaged and their color changed from red (before planting) to yellow.
Except for the two plants, there were no observed injures for the other 31 plants grown in
the 8 blocks. Before planting, the initial concentration of HMs in the shoot were in the levels
of ND (< 1.71 mg kg
-1
) to 37.2 mg Cu kg
-1
, ND (< 4.65 mg kg
-1
) to 21.7 mg Cr kg
-1
, and 8.07 to
103 mg Zn kg
-1
. These 33 plant species have low Ni concentration (< 10.1 mg kg
-1
) in their
tissues before planting, except for Bougainvillea, Common melastoma, and Garden Canna.
Although Cockscomb showed yellow flowers at second week after planting, it accumulated
the highest Cu, Cr, Ni, and Zn concentration in its shoots in relative to other plant species.
Cockscomb and rainbow pink accumulated 317±117 and 231±73 mg Cr kg
-1
in their shoots,
respectively, after
in-situ
growing for 33 days in the site. Their BCF was 1.7 in cockscomb
and 1.3 in rainbow pink.
Fig. 2. Map of Taiwan and location where the phytoremediation experiments were
conducted (Lai & Chen, 2009; Lai et al., 2010a).
