1) extraction for 1 h shaking, using a 1:10 suspension of a soil to H2O
ratio — extract of water soluble metal form.
2) extraction for 18 h, using a 1:10 suspension of a soil to 1 N NH4OAc,
pH 4.8, ratio—extract of exchangeablewater solublemetals formincluding
water soluble form.
The content of metals in strongly bound compounds was determined
as the difference between the total amount of metals in soils
and their weakly bound compound forms.
The extract fromeach stepwere filtered through paper (pore size 2–
3 μm)and analyzed by atomic absorption spectrophotometry (Scientific
Buck 200 A).