Lookup NU author(s): Dr Jan Dolfing
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Metal-contaminated soils are potentially harmful to plants, animals, and humans. Harmful effects are often related to the free-metal concentration in the soil solution, Immobilization is a potentially useful method to improve the quality of metal-contaminated soils by transforming free-metal ions into species that are less mobile and less toxic. The effect of many immobilizing products can be attributed to sorption on the surface of the material. Alkaline materials also enhance adsorption to soil particles by decreasing proton competition. Immobilization should preferably be evaluated independently of soil pH to discriminate between these processes. In this study, the immobilizing effect of beringite, an alkaline alumino silicate, was compared with that of lime. Plants (Swiss chard (Beta vulgaris L. var. cicla]) were grown on a soil contaminated with cadmium and zinc and treated with graded amounts of beringite or lime. Metal availability, as determined by a 0.01 M CaCl2 extraction, and metal uptake by plants strongly decreased in all treated soils. Beringite did not reduce metal availability more than liming when the obtained pH levels were similar. The effect of beringite can, therefore, be explained as a liming effect, at least for the duration of our experiment (10 weeks). The effect of beringite and lime on metal accumulation by earthworms (Eisenia veneta and Lumbricus rubellus) was small or not significant, although the CaCl2-extractable metal concentration in treated soils decreased by more than 90%. We conclude that immobilizing agents based on a liming effect can decrease metal uptake by plants, but they will hardly affect metal uptake by earthworms. Hence, these materials can reduce negative ecological effects of metal contamination on plants and herbivores, but not on earthworm predators.
Author(s): Oste LA, Dolfing J, Ma WC, Lexmond TM
Publication type: Article
Publication status: Published
Journal: Environmental Toxicology and Chemistry
Print publication date: 01/06/2001
ISSN (print): 0730-7268
ISSN (electronic): 1552-8618
Notes: Times Cited: 14
Cited Reference Count: 40
ENVIRON TOXICOL CHEM
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