Cadmium contamination of soils and rice plants caused by zinc mining V. Removal of soil cadmium by an HCl-leaching method for the control of high Cd rice

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Abstract
A method of leaching polluted soil with diluted HCl solution was investigated for controlling high Cd in rice. Results obtained in the pot and field experiments are summarized as follows: 1. By leaching the soil in the pot with 0.05 or 0.1 N HCl solution followed by washing with water, soluble heavy metals were remarkably removed in the order of Cd>Cu>Zn≫Pb; the Cd content decreased to half with 0.1 N HCI treatment. 2. Heavy metal contents of the plants decreased with the treatments. Especially, Cd content in straw and rice of the soil applied with CaCO3 after the treatment was one-third and one-fifteenth of the control, respectively. 3. A contaminated paddy field was similarly treated using industrial cone. HCl. One-fourth of the soluble Cd in the surface soil was removed by this method, and the Cd content of the unpolished rice decreased from 0.33 ppm to 0.06 ppm in the plot treated with fused magnesium phosphate and calcium silicate after the treatment. 4. Cd concentration of the drained water from the treated field could soon be diluted far below the allowable limit with the abundant river current. A sufficient supply of calcareous materials was needed to compensate for the lost bases in the soil.