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

This study investigated the effect of anions on the uptake of heavy metals and aluminum by Brassica rapa L. from non-contaminated, Cd-contaminated, an d sewage sludge compost (SSC)-amended sandy soil. Four types of artificial precipitation were applied: deionized water (pH 5.7) as a control, and solu tions of HNO3, H2SO4, and HCl prepared to pH 4.5. Precipitation was applied daily during the last 20 d of cultivation. The pH of the Cd-treated soil a fter harvest was not affected by any precipitation treatment. Shoot concent rations of heavy metals and Al were unaffected by any treatments on non-con taminated soil. In contrast, all acid treatments increased the Cd concentra tion in shoots grown on Cd-contaminated soil, but only HNO3 precipitation i ncreased 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. de pends on anions in precipitation and chemical form of Cd in the soil under conditions of heavy metal enrichment.