Environmental Engineering Reference
In-Depth Information
The statistical analysis was done with the Statistics 7.0 (2000) package,
processing the data for Analysis of Variance (ANOVA) for a completely
randomized design. One-way ANOVA was carried out to compare the means
of different treatments; where significant F values were obtained, differences
between individual means were tested using Tukey's test. Statistical
significance was defined as p < 0.05.
Treatment Effect on Cd Soil Fractions
The percent of total Cd associated with different fractions in the control
sample was in the following order: exchangeable fraction (55%) > organic
matter bound fraction (31%) > inorganic precipitate fraction (13%). These
results indicate that a substantial quantity of Cd in the contaminated soil may
be available for plant uptake (Basta and McGowen, 2004), in good agreement
with results reported by Chen et al, (2007). The concentrations of Cd in the
different soil fractions following treatments in each sampling date are shown
in Figures 1, 2 and 3.
7
CS
6
a
a
C1
a
C2
5
C3
4
C3+L
3
L
2
b
b
b
1
0
0
14
28
42
days
Figure 1. Water-soluble and exchangeable fraction of Cd (EXCH-Cd) in the
contaminated soils as a result of the addition of amendments: SC: control, Ci: soil
amended with compost i; L: soil amended with lime. For each date, different letters
indicate significant differences according to Tuckey's test at 5% probability level (n =
3).
Changes in Cd Water-Soluble and Exchangeable Fraction (EXCH-Cd)
The addition of C1, C2 or C3 did not significantly modify EXCH-Cd over
the incubation period compared to control (Figure 1), which ranged from 47 to
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