The immobilization of toxic metals in soils
using amendments is a cost-effective remediation technique
for contaminated soils. Therefore, this study aimed to
assess the efficiency of various amendments to immobilize
nickel (Ni) and zinc (Zn) in soil and reduce their phytoavailability.
A greenhouse pot experiment was established
with a contaminated agricultural floodplain soil. The soil
was treated with activated carbon (AC), bentonite (BE),
biochar (BI), cement bypass kiln dust (CBD), chitosan
(CH), coal fly ash (FA), limestone (LS), nano-hydroxyapatite
(HA), organo-clay (OC), sugar beet factory lime
(SBFL), and zeolite (Z) with an application rate of 1 %
(0.2 % for HA) and cultivated by rapeseed (
Brassica napus
).
After plant harvesting, the soil was analyzed for
water-soluble and geochemical fractions of Ni and Zn.
Additionally, both metals were analyzed in the aboveground
biomass. Application of the amendments increased
significantly the biomass production of rapeseed compared
to the control (except for OC, HA, and FA). Water-soluble
Ni and Zn decreased significantly after adding the
amendments (except OC, Z, and CH). The SBFL, CBD,
LS, BE, AC, and BI were most effective, resulting in a
58–99 and 56–96 % decrease in water-soluble Ni and Zn,
respectively. The addition of SBFL, CBD, and LS leads to
the highest decreasing rate of concentrations of Ni in plants
(56–68 %) and Zn (40–49 %). The results demonstrate the
high potential of CBD, SBFL, LS, BE, AC, and BI for the
immobilization of Ni and Zn in contaminated floodplain
soils.
