Two-year stability of immobilization effect of sepiolite on Cd contaminants in paddy soil
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The long-term stability of immobilization effect of immobilization agents was critical to the remediation practices. Two years consecutive in situ field-scale demonstration was conducted in Hunan province, with the purpose to certify the long-term stability of immobilization effect of sepiolite on Cd contaminants in paddy soil in the aspect of soil extraction and plant uptake. Natural sepiolite was selected as immobilization, and rice was the model plant. The immobilization effect of sepiolite on Cd contaminants in paddy soil was significant in the first year and remained at the second year. The Cd content of brown rice, 0.025 M HCl extractable Cd content and exchangeable Cd content of paddy soil decreased remarkably. The application of sepiolite led to an obvious increase in pH value of paddy soil and carbonate bounded fraction of Cd in soil. The immobilization effect was maintained even at the second year without any additional amendments. The results indicated the interaction of sepiolite and cadmium was a long-term process. The additional sepiolite at the second year had no significant lift effect on immobilization so that it was unnecessary to add sepiolite every year based on the immobilization effect and operation cost. The dynamics of available Cu, Zn, and Mn contents in paddy soil in two consecutive years indicated sepiolite had negligible effects on the bioavailability of trace metals. The result of the current research confirmed the stability of immobilization effect of sepiolite.
KeywordsStability Immobilization Sepiolite Cadmium
This research was supported by the Central Public Research Institutes Basic Funds for Research and Development (2015-szjj-wrxf-lxf), National Natural Science Foundation of China (no. 41401362, 31200397, and 21177068) and Special Fund for Agro-scientific Research in the Public Interest (no. 201203045).
- Bolan NS, Makino T, Kunhikrishnan A, Kim P-J, Ishikawa S, Murakami M et al (2013) Cadmium contamination and its risk management in rice ecosystems. In: Donald LS (ed) Advances in agronomy, vol 119. Academic, Amsterdam, pp 183–273Google Scholar
- Kikuchi T, Okazaki M, Kimura SD, Motobayashi T, Baasansuren J, Hattori T et al (2008) Suppressive effects of magnesium oxide materials on cadmium uptake and accumulation into rice grains: II: suppression of cadmium uptake and accumulation into rice grains due to application of magnesium oxide materials. J Hazard Mater 154(1–3):294–299CrossRefGoogle Scholar
- Pedler JF, Parker DR (2006) Copper. In: Lal R (ed) Encyclopedia of soil science. Taylor & Francis, London, pp 345–347Google Scholar