EFFECTS OF PHOSPHORUS AND IRON COMPOUNDS ON ARSENIC UPTAKE BY SELECTED VEGETABLE SPECIES FROM SOILS POLLUTED WITH THIS ELEMENT

摘要

A pot experiment was carried out to evaluate the effects of phosphates and soluble iron (II) salts on plant growth and As uptake by plants from soils polluted by long-lasting mining and processing of gold and arsenic ores. The experiment was performed with three plants species: cucumber, bean and spinach, and two soils containing different concentrations of As: 203 and 421 mg/kg. Compared were plant growth, As uptake and As solubility in soils as affected by additions of phosphate (diammonium phosphate (NH_4)_2HPO_4), and iron salt (ammonium iron sulphate (NH_4)_2Fe(SO_4)_2). Easily soluble As ((NH_4)_2SO_4 -extractable) and specifically bound As (NH_4H_2PO_4 - ex-tractable) were determined in soils before and after the pot experiment. Addition of phosphate resulted in significant increase of easily soluble As in soils whereas iron sulphate significantly decreases soluble As. Specifically bound As remained unaffected. From among the plant species tested, cucumber appeared the most sensitive to high soil As concentrations. As concentrations in plant shoots were in the range 1.12-18.0 mg/kg d.m. and it the case of cucumber and spinach depended on P or Fe additions. In all plots, As concentrations in spinach shoots were much lower than those in cucumber and bean.