Relation between trophic state index and land use in permanent preservation areas of the Paraíba do Sul River

Authors

  • Lucas Queiroz Universidade de São Paulo
  • Daniel Clemente Vieira Rêgo da Silva
  • Rodrigo José Marassi
  • Caio César Achiles do Prado
  • Flávio Teixeira da Silva
  • Teresa Cristina Brazil de Paiva

Keywords:

Riparian zones, Eutrophication, Cyanobacteria, Water scarcity, Water quality

Abstract

The present study aimed to correlate the variables that could influence the water quality of Paraíba do Sul River (PSR), such as vegetation cover in the permanent protection areas (PPA), rainfall, and the Trophic State Index (TSI). The riparian zones were classified according to the vegetation cover from satellite images, as follows: Tree plant cover (TPC), Permeable area (PER), and Impermeable area (IMP). The total phosphorus (TP) and chlorophyll-a (CL) concentrations in the collected water were used to determine the TSI. A multivariate correlation analysis was carried out using the TSI values, rainfall, and vegetation cover. Also, the presence of cyanobacteria was evaluated. We observed a higher occurrence of IMP and PER in the riparian zones. The TP and CL concentrations increased during rainy periods, mainly in PER. The multivariate analysis demonstrated that the terrestrial areas influenced significantly the PSR parameters. PER contributed to the impairment of the water quality from the PSR, particularly in the rainy period. The presence of toxin-producing cyanobacteria was detected in the PSR. Our results reinforce the necessity to preserve and promote the restoration of the riparian areas in watersheds, mainly in the PSR.

Published

2021-10-03