Chloride as a Factor in Mobilities of Ni(II), Cu(II), and Cd(II) in Soil

An investigation was undertaken to study the mobility of chlorocomplexes of Ni(II), Cu(II), and Cd(II) through soil. Soil columns were leached with 0.1, 0.2, 0.3, or 0.5 M NaCl or NaClO 4 solutions, each containing 10 µ g/ml Ni(II), Cu(II), or Cd(II). Sodium perchlorate solutions were used as a comparison with NaCl at the same ionic strength since perchlorate is not considered to form complexes with the metals. Leachates from columns and soils were collected and analyzed. Mobility of all metals tested in chloride solutions was from 1.1 to 4 times greater than that in ClO 4 ‐ solution. Chloride increased the mobility of Cd(II) the most which corresponds to its having the largest stability constants. Cooper (II) was slowest to appear in the leachate and was strongest adsorbed as evidenced by analysis of soil by digestion with either 4 N HNO 3 or acidified NH 2 OH‐HCl. These results showed that Cl ‐ has a marked effect on the mobility of Cd(II) and, to a lesser extent, Ni(II) and Cu(II).