Perspectives of using the water hyacinth (Eichhornia heterosperma) for self-purification in a Colombian water reservoir

Abstract

<jats:p>Eutrophication and heavy metal contamination of freshwater reservoirs cause serious problems world- wide. With increasing nutrient levels in lakes and reservoirs, invasive macrophytes like the perennial water hyacinth <jats:italic>Eichhornia</jats:italic> spp. can intensify the degradation process, but the plants can also be supporting because of their high capacity for heavy metal and nutrient accumulation. In this study, we assessed the potential of <jats:italic>E. heterosperma</jats:italic> for nutrient removal. Therefore, we measured nutrient and heavy metal concentrations in the water and the plant tissue of <jats:italic>E. heterosperma</jats:italic> plants harvested in a hypereutrophic reservoir (Porce II, Antioquia, Colombia). We found mean nitrogen concentrations between 21–45 g and phosphorus between 2.1–3.0 g kg <jats:sup>–1</jats:sup> dry weight in the different plant parts (leaves, stems, roots). Regarding metals, we measured 3.1–2;37 mg chrome, 62 mg–7.4 g aluminium, 22–70 mg zinc, 12–95 mg copper, and 0.4–1.3 g manganese per kg of dry weight. This exceptional high ability for nutrient and heavy metal uptake makes <jats:italic>Eichhornia heterosperma</jats:italic>an appropriate candidate for bioremediation in reservoirs. Therefore, we assessed the potential of the plants as fertilizer for forests and agriculture regarding the heavy metal accumulations. We found that the harvest of 1.0 km² of plant cover in Porce II would result in a removal of 4.3 % phosphorus and 4.0 % nitrogen of the nutrients in the water column. This indicates that for hypereutrophic lakes with an annual input of about 43443 t N and 2490 t P, the remediation capacity of this plant is limited.</jats:p>