Analysis of Phosphorus Behavior in the Giant Reed for Phytoremediation and the Biomass Production System

Abstract

Macrophyte-cultivated wetlands have a strong potential not only to purify eutrophic water but also to produce biomass resources. Among a variety of macrophytes, we focused on the giant reed (Arundo donax), and its properties of phosphorus uptake, accumulation, and translocation were clarified in this study. Phosphorus uptake experiments using outdoor hydroponic culturing showed the seasonal variation of phosphorus uptake by the giant reed. Furthermore, two kinetic parameters describing the phosphorus uptake by the giant reed were obtained. Phosphorus accumulation experiments using radioactive phosphorus suggested that giant reeds accumulate the absorbed phosphorus in rhizomes, and it is then distributed to the leaves if needed. A phosphorus translocation experiment using radioactive phosphorus indicated that the decreasing of phosphorus in the leaves occurred in the order of location from the bottom to the top, which is relevant to the order of dying down of the plant leaves actually observed in this study. Based on these outcomes, a desirable management method for the giant reed cultivated in wetlands is proposed.