Environmental Engineering Reference
In-Depth Information
Liming of contaminated soils is the most widely used remediation
treatment to reduce the bioavailability of Cd (Bolan et al. 2003 b; Tlustoš et
al., 2006; Hong et al, 2009). Alkaline amendments increase soil pH (McBride
et al., 1997 and Filius et al., 1998) and facilitate the formation of oxides,
metal-carbonate precipitates and complexes that decrease metal solubility
(Mench et al., 1994). Biosolids´ compost can therefore be combined with
alkaline materials to complement Cd sequestering ability on compost
components (Mench et al., 1994 and Chlopecka and Adriano, 1996). Recent
studies have shown that alkaline-stabilized biosolid compost that are low in
total and/or bioavailable metal content can be used as an effective sink for
reducing the bioavailability of Cd in contaminated soils (Brown et al., 2000; Li
et al., 2000; Basta et al., 2001; Clemente et al., 2005). Numerous
investigations have been carried out for biosolids compost as potential
contamination sources of heavy metals. Conversely, limited work has been
done regarding the capacity of biosolids compost obtained at different stages
of the composting process, lime and a mixture of mature compost and lime to
immobilize Cd on an artificially Cd contaminated soil of the Pampas Region,
Argentina. These aspects are further discussed.
3.2.1. Immobilization Studies on a Typical Soil of the Pampas Region,
Argentina Soil
The study selected a typic Argiudoll (U.S. Soil Taxonomy) of the Pampas
Region, Argentina. Pristine topsoil samples (<20 cm depth) were collected
from San Antonio de Areco town (34° 15' S - 59° 29' W). The samples were
homogenized, air-dried, and ground to pass through a 2-mm plastic sieve. The
main physico-chemical characteristics of the soils are presented in Table 1.
Table 1. Selected properties of the soil and the
organic amendments used in the study
pH
EC
% C
Soluble C
Texture (%)
CEC
2
Total
Cd
(dS m-
1)
%C
Clay
(%)
Silt
(%)
Sand
(%)
(cmol
kg
-1
)
(mg kg
MS
-1
)
Conta-minated
soil
5.72
0.7
2.02
-
30.3
53.6
16.1
24.5
10.94
Compost 1
7.5
2.10
13.42
0.24
24
<4
Compost 2
7.6
2.08
11.08
0.06
18.13
<4
Compost 3
7.6
2.62
4.05
0.031
14.3
<4
1
EC:
Electrical Conductivity.
2
CEC: Cation Exchange Capacity.
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