• English
  • Português

Data of Thesis

Author: Cesar Macedo Lima Filho
Title: Evaluation of the capacity of phytoremediation by Eichhornia crassipes (Mart.) Solms (Pontederiaceae)
Year: 2019                                         Full text (in Portuguese)
Eutrophication of water bodies is a worldwide problem. Eichhornia crassipes is a floating macrophyte with ability to remove nutrients from eutrophic aquatic environments and can be used for phytoremediation. This study was performed in the Barra do Braúna hydroelectric plant (MG, Brazil). A system consisting of 5 cascading mesocosms at decreasing heights was constructed (total volume on 15,000 L). The system was fed with water from the reservoir and sustained a flow of q = 89 L/h. To simulate a hypereutrophic state, NPK 10-10-10 was added to the system to increase the concentration of PO4 3- to 400 μg/L. To evaluate the phytoremediation capacity of E. crassipes, 30 plants were placed in each mesocosm. Two experiments were performed: one in the rainy season, summer (February - March) and the other in the dry season, winter (July - August), with a duration of 6 weeks each. The following parameters were evaluated: water conductivity, pH, O2 concentration, temperature, concentration of inorganic nutrients (PO4 3+, Ptotal, NH4 + , NO3 - , Ntotal), chlorophyll-a, macrophyte coverage, dry biomass, Ntotal and Ptotal of macrophytes. In both experiments, the concentrations of dissolved nutrients (PO4 3- , NH4 + e NO3 - ) in the system were reduced, but the efficiency of nutrient removal by the macrophyte was higher in summer (53% removal of P, 17% removal of N) than in the winter (23% removal of P, 4% removal of N). These results were due a higher macrophyte growth rate in summer (0.57 m2/day) than in the winter (0.35 m2/day), resulting in a higher coverage and dry biomass value. In both periods the concentration of chlorophyll-a decreased, from 70.0±36.1 μg/L to 6.9±10.0 μg/L in summer, and from 17.0±5.1 μg/L to 3.6±3.0 μg/L in winter. Thus, E. crassipes can remediate euthophication and as consequence control phytoplankton growth. The management of the macrophyte coverage at Barra do Braúna reservoir represents a potential solution to mitigate cyanobacterial blooms.