A statistic analysis was made for samples of active state elements determined by ICPMS from July to

Decembers. Precisions of the 6step sequence extraction method for Cr, Cu, Zn, Cd and Pb were as follows:

waterextractable metals, 5.4%~60.1%; ionexchangeable metals, 10.8%~62.9%; carbonate bound metals, 8.0%~26.6%;

organically bound metals, 6.6%~27.3%; occluded metals in iron and manganese oxides, 5.3%~13.6%; and strongorganically

bound metals, 8.5%~33.5%. The detection limit and signaltonoise ratio of the method were also investigated. The

results show that the determinations of occluded metals in iron and manganese oxides are stable and credible, but the

stability and sensitivity of waterextractable metals and ionexchangeable metals need to be improved.