Five macrophytes, namely Crinum asiaticum L. (Amaryllidaceae), Lepironia articulata (Retz.) Domin (Cyperaceae), Machaerina rubiginosa (Spreng.) T. Koyama (Cyperaceae), Pandanus sp. (Pandanaceae) and Nepenthes mirabilis (Lour.) Druce (Nepenthaceae), were identified in the Kawasi wetland, a natural wetland on Obi Island, Indonesia, that overlies ultramafic rocks. The dominant species in this wetland was C. asiaticum, a native of the region. The surface runoff in the catchment of the Kawasi wetland was derived from serpentine soils, areas of which were being mined for nickel and, as a result, the water that flowed to the wetland typically contained dissolved chromium and nickel. In this study we investigated the accumulation of chromium and nickel in the macrophytes of the wetland. The five species of macrophytes under investigation accumulated greater quantities of chromium and nickel in their roots than in their shoots, with Pandanus sp. having the highest translocation factor (as evidenced by the highest shoot : root ratio) for both chromium and nickel. The species with the highest concentrations of the metals in both roots and shoots was C. asiaticum.
