Treating plants with chelates - to reduce content of harmful heavy metals, esp. lead

摘要

Plants contaminated or subject to contamination with harmful heavy metal (esp. Pb) ions are treated with at least one of the water-soluble salts of ethylenediaminetetra-acetic acid (EDTA) or of an oligophosphoric acid of the formula: (where n is not 1). The treatment is applied by spraying to the plot in which the plants are growing, or alternatively the plants are washed with an aqs. soln. of the water-soluble salt of EDTA or of (I) during technical processing after harvesting. EDTA and (I) form with harmful heavy metals complexes which cannot be assimilated by plants. When EDTA or (I) salts are applied in the field, the heavy metal complexes remain in the leaf or root surface and are readily washed away by rain. A similar elimination of heavy metals is found to occur when already contaminated plants are washed with an aqs. soln. of water soluble salt of EDTA or (I). The amt. of EDTA salt used in spray or wash solns. is pref. up to 5 mol. per equivalent of metal ions to be removed, provided that the total EDTA concentration does not exceed 5 mmol./litre. The water soluble salts of (I) are pref. added to the spray or washing soln. in a concn. of is not 1%.