COMPARISON OF 2 SEQUENTIAL EXTRACTION PROCEDURES FOR SPECIATION ANALYSIS OF METALS IN SOILS AND PLANT AVAILABILITY

Soil and plant samples were collected from 12 different rural areas of Beijing, China. Metals [calcium (Ca), iron (Fe), manganese (Mn), copp er (Cu), and zinc (Zn)] in the soils were partitioned by the Tessier's and BCR's sequential extraction procedures. The results obtained show ed significant correlation between the metals extracted in the three s teps of the BCR's procedure and that extracted in the corresponding st eps of the Tessier's method. The correlations were identical whether u sing the Tessier's or BCR's procedure in evaluating plant availability of soil metals. Correlation analysis indicated that the Zn and Mn con tents in the plant were positively correlated to Zn and Mn bound to Fe -Mn oxides in the soil. However, the Ca content in the plant was negat ively correlated to Ca bound to carbonates in the soil. The Fe and Cu content in different parts of corn were not significantly correlated t o the different metal forms in the soil. The ''best'' regression equat ions were obtained by stepwise multiple regression analysis to predict the metal absorption by corn.