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The adsorption of Na on a prepared hydroxy‐aluminum‐montmorillonite complex (OH‐Al‐SWy‐l) was investigated as a function of pH, time, and Cu concentration ([Cu]). It was found that Na adsorption from 0.01M NaClO4 increased with pH from 0.015 mol kg−1 at pH 4.5 to 0.33 mol (Na+) kg−1 clay at pH 6.6 Adsorption of 0.16 mol (1/2 Cu2+) kg−1 clay did not affect the amount of Na adsorption, showing that specific sites existed for Cu. Adsorption of Cu was found to increase with pH and both adsorption and resistance to extraction with 0.25M Ba(NO3)2 increased with time. At pH 4.6, Cu adsorption approached a maximum near 0.3 mol (1/2 Cu2+) kg−1 clay of which 0.13 mol (1/2 Cu2+) were extracted with Ba(NO3)2. Electron spin resonance (ESR) of the Cu on OH‐Al‐SWy‐l showed that both physi‐ and chemisorbed Cu were present and that solubilization as Cu(NH3)2+4 through exposure to NH3 vapor overnight was possible only if the sample had been previously treated with BaCl2. It was concluded that the OH‐Al‐SWy‐l system provided a much more reactive surface toward Cu adsorption than either montmorillonite or hydrous aluminum oxides. In comparison to smectites Cu was less labile to Ba extraction due, in part, to chemisorption by Al‐OH groups. Relative to values reported for Al(OH)3 polymorphs, Alx(OH)y3x‐y precipitated in the presence of montmorillonite adsorbed more Cu on a mass basis presumably due to a higher surface to mass ratio.

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 0.5M NaCl or NaClO4 solutions, each containing 10 µg/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 ClO4‐ 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 4N HNO3 or acidified NH2OH‐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).