Exchangeable Metals. Concentrations found for exchangeable cadmium, cobalt, nickel, lead, and zinc are
lower than their respective detection limits; low concentrations of copper (0.15 and 0.2 ppm) and iron (0.4 ppm) are observed, as are relatively high concentrations of manganese (99 and 38 ppm). For the latter element, fraction 1 accounts for 14-3% of the total metal concentration.