In a field experiment we investigated the efficiency of two hyperaccumulating species, four agricultural crop plants, and one woody crop, at phytoextraction of Zn, Cd, and Cu from a polluted calcareous soil. In addition, we examined the possibility to enhance the phytoextraction of these metals by application of nitrilotriacetate (NTA) and elemental sulfur (S 8 ) to the soil. Metal uptake by hyperaccumulating species was higher than that by crop species but was generally low in all treatments compared to results reported in the literature, maybe as a result of lower total and available soil metal concentrations. Soil amended with either S 8 or NTA increased the solubility (NaNO 3 -extraction) of Zn, Cd, and Cu ions by factors of 21, 58, and 9, respectively, but plant accumulation of these metals was only increased by a factor of 2-3. As a result, even the highest metal removal rates achieved in this study were still far from what would be required to make this technique practicable for the remediation of the Dornach field site. To extract for example 50% of the total Cu, Zn, or Cd present in this soil within 10 years, plant metal concentrations of 10.000 mg kg -1 Cu or 10.000 mg kg -1 Zn or 45 mg kg -1 Cd would be required at a biomass production of 7.8 t ha -1 , or 10t ha -1 , or 10t ha -1 , respectively, assuming a linear decrease in soil metals.

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ZusammenfassungCertain wild plants as well as crop plants, so-called hyperaccumulators, are able to accumulate large amounts of heavy metals in aerial parts. This property may be exploited for the clean-up of soil contaminated by metals (phytoremediation), if the yield and metal accumulation are big enough to finish remediation within a reasonable period (e.g. five years). Therefore, the ability of various plants to accumulate zinc and cadmium were compared in field trials. The wild species Thlaspi caerulescens and Alyssum murale as well as the tree Salix viminalis showed a strong ability to accumulate zinc and cadmium. However, phytoremediation of investigated soils contaminated with cadmium (6.6 ppm) or zinc (810 ppm) lasts too long based on present technology, Literature data and preliminary experiments indicate that major obstacles could be overcome: Yield and metal-uptake rates have to be increased dramatically in order to allow remediation within reasonable periods.

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J. 1987. Association of polyamines to different parts of various plant species. -Physiol. Plant. 71: 245-250.The variation in polyattiine content in different plant species and in different parts within a plant can be considerable. To get genera! information about levels of polyamines in plants and about the association of polyattiines to different types of tissue, 30 plants from 13 plant families were examined for their polyamine content before and after gennination using high pressure liquid chromatography (HPLC) analysis. A marked increase in polyamine content occurs in the cotyledons or etidosperms in the seeds on germination, i.e. in the nutrient storing and exporting part of the plant. In the radicle, hypocotyl or coleoptile, i.e. growing parts of the plant, an increase in polyamine content is rarely observed. Additionally, polyamine levels can be very low [below 1 nmol (g fresh weight)''] in different parts of various species. Obviously, levels in the pmol (g fresh weight) ' range satisfy the needs of many growing plant parts. The high levels of polyamines found especiaDy in cotyledons cannot be explained by their postulated association with increased cell division rates.