Changes in the allocation of some chemical compounds in structures of Oryza glumaepatula (Steud) in an Amazonian lake subjected to an anthropic impact (Lake Batata, Porto Trombetas)

Lake Batata is a typical clear water lake of the Amazon, located at the right margin of the Trombetas River, at the town of Porto Trombetas (PA). It is subjected to a large and predictable variation of the water level, greater than 6 m, being in the floodplain of the Trombetas River. For 10 years (1979–1989) Lake Batata has received the tailings of bauxite processing from the activities of Mineração Rio do Norte S.A. These tailings impacted about 30% of its total area with an effluent of fine granulometry. Nowadays, two different areas can be observed at Lake Batata, one impacted by the bauxite tailings and one where the natural characteristics have been preserved. The aquatic macrophyte Oryza glumaepatula (Steud), known as wild rice, is one of the species found in the two areas, impacted and natural. The goal of this research was to evaluate the concentration of organic matter, organic carbon, N, P, lipids, soluble carbohydrates, and cell-wall fraction in three structures of O. glumaepatula (leaves and culm, adventitious roots, and basal roots), as well as to identify the possible differences in the allocation of these compounds between individuals in the natural and impacted areas. While the differences between the different structures of the plant are preliminary data for studies on the detritus chain and herbivory, the differences between the natural and impacted areas show the probable impact of the tailings on O. glumaepatula.