Simulated effects of metal load, soil organic matter and pH on the solubility of Cd, Cu and Zn in Fluvisols and Acrisols in SE Asia

摘要

A multi-surface model including soil organic matter (SOM), hydrous ferric oxide (HFO) and clay minerals was used to test various scenarios on soils representing Vietnamese Fluvisols and Acrisols. Two sites located in peri-urban areas of Hanoi were used as well as data from the national soil inventories. The scenarios included (i) changing metal loading (Cd, Cu, Zn) up to the maximum acceptable soil concentration (MAC), and (ii) varying the SOM content and (Ⅲ) soil pH within the range being recorded in these soil groups. Cadmium and Zn accumulation in Acrisols up to the present MAC (Cd 2mg·kg<'-1>, Zn 200mg·kg<'-1>) might most probably lead to dissolved metal concentrations above the ground water quality standards (Cd 0.01mg·L<'-1>, Zn 5.0mg·L<'-1>) whereas in Fluvisols they were predicted below the thresholds. This might lead to risks for enhanced metal concentrations in agricultural products and drinking water jeopardizing human health. The MAC for Cu (50mg·kg<'-1>) was estimated to give soluble concentrations below the water standard (<1.0mg(Cu)·L<'-1>) for most Acfisols as well as for Fluvisols. SOM was a major factor regulating the metal solubility together with pH (for Cd, Zn). However, in the long term organic matter applied by biosolids and wastewater will decompose, potentially increasing the solubility of the metals being enriched in the soils.