Fraction	Metal sequential extraction scheme
	Extraction method for 0.5 g initial sample. Samples are centrifuged, filtered and the residue rinsed with 10 ml DI water between extractions
Exchangeable: Metals loosely bound to soil particles by ion exchange mechanism are displaced by the weak acid	10 ml 0.11 M acetic acid at room temperature, with constant agitation
Reducible: Iron and manganese oxides are plentiful in soils and have coprecipitated metals bound in them. This reduces the oxides and frees the bound metals	20 ml 0.1 M Hydroxylamine hydrochloride, acidified to pH 2 with HNO3. Agitated at room temp for 16 hr.
Oxidizable: Organic materials which contain metals are destroyed by oxidation, freeing the metals	5 ml 8.8 M H2O2, 1 hr. with occasional agitation. Heat at 85 ^oC 1 hr, evaporate to few ml, add 5 ml more H2O2, evaporate to near dryness, cool and add 25 ml 1 M ammonium acetate, acidified to pH 2, and agitate for 16 hr.
Residual: Anything which is left, bound up in the structure of the minerals comprising the soil or sediment is dissolved	Digest with HF, HNO3, HClO4