Amelioration of Cadmium Contaminated Soils Using Cation Exchangers

ABSTRACT

The contamination of soil and water with cadmium (Cd) is an environmental issue worldwide. Using lettuce (Lactuca sativa cv. ‘Cos’) in a glasshouse-based growth trial, two cation exchange materials [a zeolite and a kaolin amorphous derivate (KAD)] were examined for their ability to remove Cd from the soil solution and hence decrease the uptake of Cd by plants. Zeolite (applied at a rate of 2.5 t ha^{− 1}) was ineffective at reducing Cd uptake and accumulation in lettuce. When applied at a rate of 2.5 t ha^{− 1}, the KAD significantly reduced Cd uptake in all soils examined (ranging from a 26 to 64% reduction). Thus, KAD is considered to be potentially beneficial for the growth of plants in Cd-contaminated soils, although care must be taken to ensure that growth is not limited by deficiencies of the other nutrients for which KAD has a high affinity.

Keywords:

• cadmium (Cd)
• kaolin amorphous derivatives (KAD)
• phytotoxicity
• uptake

ACKNOWLEDGMENTS

The authors acknowledge the assistance of Michael Geyer with the chemical analyses and soil preparation, Ian McKinnon from the Centre for Microscopy and Microanalysis (The University of Queensland) for the KAD, and Mike Bell from Queensland Department of Primary Industries and Fisheries for the Cd-contaminated soils. The statistical advice of Rosemary Kopittke was also gratefully received. This research was funded through the Cooperative Research Centre for Contamination, Assessment, and Remediation of the Environment (CRC-CARE) Project 3-3-01-05/6.

Notes

∗Numbers in a column with the same superscript letter are not significantly different (P ≤ 0.05).

^†No significant interaction (P > 0.05) between the soils and the cation exchanger treatments, but significant differences (P ≤ 0.05) in the cation exchanger treatments (i.e. the LSD allows comparison between the exchanger treatments averaged across the three soils).

^‡Significant interaction (P ≤ 0.05) found (i.e. the LSD allows comparison between soils and between the cation exchanger treatments).