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  • 1
    Electronic Resource
    Electronic Resource
    Measurement of Pb2+, Cu2+ and Cd2+ binding with mucilage exudates from maize (Zea mays L.) roots (1986)
    Springer
    Biology and fertility of soils 2 (1986), S. 29-34 
    Details
    ISSN: 1432-0789
    Keywords: Root mucilages ; Maize ; Lead ; Copper ; Cadmium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The pectic nature of root mucilages suggests a hypothetical action of these substances on heavy metal flux into the root. In this study the existence of relations between heavy metals and root mucilages were verified and quantified. In order to obtain substantial amounts of pure root mucilages, two methods of collection were developed, using: (1) maize plants grown in the field and (2) hydroponic axenic cultures. The study of mucilage-metal binding was conducted using the dialysis method, which was developed in a previous work. Results show that root mucilages are able to bind metals. The importance of the binding depends on the nature of the cation, following the order Pb 〉 Cu 〉 Cd. These reactions could be due to exchange processes involving mucilage cations (Ca2+, Mg2+) and heavy metals. The role of mucilages on the retention of heavy metals in the rhizosphere is also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00638958
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  • 2
    Electronic Resource
    Electronic Resource
    Comparison of the adsorption of maize root mucilage and polygalacturonic acid on montmorillonite homoionic to divalent lead and cadmium (1987)
    Springer
    Biology and fertility of soils 5 (1987), S. 13-17 
    Details
    ISSN: 1432-0789
    Keywords: Maize root mucilage ; Polygalacturonic acid ; Montmorillonite ; Lead ; Cadmium ; Adsorption isotherms ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Root mucilage material (RM) was isolated from maize plants grown in the field, and its affinity to montmorillonite (M) homoionic to Pb2+ and Cd2+ was compared with that of a commercial polygalacturonic acid (PGA). Adsorption isotherms of the commercial and natural materials on the two clay systems were compared in unbuffered systems at pH 3 and pH 6. Adsorption of PGA occurred only at pH 3, and was higher on M-Pb than on M-Cd. In contrast, the adsorption of RM was higher on M-Cd than on M-Pb. Total amounts of RM adsorbed at pH 3 were about 3 times lower on M-Cd and 20 times lower on M-Pb than the respective amounts of PGA adsorbed at the same pH. Polygalacturonic acid had a high content of relatively well dissociated (pKa = 3.5) carboxylic groups, and adsorbed on the clay surface at pH values lower than its pKa. At pH 6, the dissociation of the acid groups favoured its solubility, and the metal cations were then probably displaced by ion exchange. The lower affinity of RM to the clay materials was related to its average molecular weight, which was lower than that of PGA, and to its water solubility, which was higher than that of PGA. The low pH dependence of the adsorption of RM was related to its lower carboxylic acidity and higher content in hydroxyl and amino groups.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00264339
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