To measure water-extractable metal concentrations,
an oven-dried soil:distilled water suspension (1:2.5 = w:w)
was prepared, shaken for 2 h at 200 rpm and filtered over a 0.45 μm
Whatman filter. Cu and Pb concentrationsweremeasured by atomic absorption
spectrometry equipped with a graphite furnace unit (Perkin-
Elmer 5100)