Forms and bio-availabilities of exogenous arsenic in purple soils

This study showed that after As was added into purple soils for 10 days, 50.2%-61.1% of it transformed into residual As, occupying 68%-86% in original soils. For acid purple soil, the As forms were Al-As > Fe-As> Ca-As; for neutral purple soil, they were Ca-As > Al-As > Ca-As > Fe-As > A-As, and for calcic purple soil, they were Ca-As > Al-As > Fe-As >A-As. It is suggested that NH4Cl could be used as common extractant for different soils, because it slightly affected original As forms in soils, and showed a highly significant correlation (P = 0.01) to plant absorption. From pluralistic regressive analysis of plant As content and each As form, Al-As and Fe-As were the main available forms in acid purple soil, but A-As and Ca-As were the most important fractions in neutral and calcic purple soils. The study also showed that H3BO3 could restrain the F interference in the operation of As speciation separations.