EFFECT OF ANIONS IN SIMULATED PRECIPITATION ON THE UPTAKE OF HEAVY METALS AND ALUMINUM BY BRASSICA RAPA L. GROWN IN HEAVY -METAL -CONTAMINATED SANDY SOIL

摘要

This study investigated the effect of anions on the uptake of heavy metals and aluminum by Brassica rapa L. from non-contaminated, Cd-contaminated, and sewage sludge compost (SSC)-amended sandy soil. Four types of artificial precipitation were applied: deionized water (pH 5.7) as a control, and solutions of HNO_3, H_2SO_4, and HC1 prepared to pH 4.5. Precipitation was applied daily during the last 20 d of cultivation. The pH of the Cd-treated soil after harvest was not affected by any precipitation treatment. Shoot concentrations of heavy metals and Al were unaffected by any treatments on non-contaminated soil. In contrast, all acid treatments increased the Cd concentration in shoots grown on Cd-contaminated soil, but only HNO_3 precipitation increased it in SSC-amended soil. These results indicate, even without large soil pH change, there is a possibility that the Cd uptake by B. rapa L. depends on anions in precipitation and chemical form of Cd in the soil under conditions of heavy metal enrichment.