Heavy metal content and distribution within a woody plant during and after seven years continuous growth on municipal solid waste (MSW) bottom slag rich in heavy metals

• Main Authors: Gimmler, Hartmut, Carandang, Jose, Boots, Astrid, Reisberg, Elfriede, Woitke, Markus
• Format: text
• Published: Animo Repository 2002
• Subjects: Datura—Effect of heavy metals on; Biology
• Online Access: https://animorepository.dlsu.edu.ph/faculty_research/3741
• Institution: De La Salle University

As we are interested in long-living woody plant performance during and after long-time exposure to high concentrations of heavy metals in the soil, Datura hybrids (as a model plant for a woody species) were grown for seven years on municipal solid waste (MSW) bottom slag. Since only few woody plants cope well for longer times with high amounts of heavy metals within the soil, we analysed Datura for its chemical composition, morphological root parameters and physiological features (root respiration, photosynthesis). Special attention was paid to the distribution of heavy metals with respect to functional different parts of the plants (roots, shoots, leaves and flowers) and functionally equal parts bur of different age (kinetic performance, cross-sectional and longitudinal distribution). Datura plants grown on slag did exhibit elevated heavy metal contents in comparison to control plants, but the observed levels are by far lower than those causing phytotoxic effects. The relative modest uptake of heavy metals is assumed to be due to 1) the akaline pH of the soil solution, causing low solubility of heavy metals in the soil solution, 2) the high Ca2+ content of slag, causing low competition of divalent cationic heavy metals during uptake, and 3) the high Ca2+ to Mg2+ ratio. No age-dependent increase of heavy metals was observable, neither for roots nor for shoots. Data imply that the growth rate of Datura hybrids on slag is faster than the tares of uptake of heavy metals from this soil substrate: Growth of the shoot produces sinks for heavy metals, e.g. binding sites at the cell wall constituents. Only when all these binding sites are occupied, the translocation of heavy metals to the leaves will approach the rate of heavy metal uptake by the root system. Otherwise, the delivery of heavy metals taken up by the roots and translocated via the shoot system to the annually produced leaves remains moderate. Data obtained from experiments with Datura may indicate that woody plants per se are not less compatible on heavy metal polluted soils than herbal plants.