Trophic state of water in the watershed of Lake Mirim, RS, Brazil

  • Ronaldo Fia Universidade Federal de Viçosa
  • Antonio Teixeira de Matos Universidade Federal de Viçosa
  • Paulo Carteri Coradi
  • Orlando Pereira-Ramirez
Keywords: Eutrophication, nutrients, phosphorus, Trophic State Index

Abstract

The objective of this work was to analyze the spacetime variations in the trophic characteristics of the principal water bodies feeding Lake Mirim, in the state of Rio Grande do Sul, by determination of the Trophic State Index proposed by Toledo Jr. (IETT) and Lamparelli (IETL), to assess water quality data between 1996 and 1998. It was verified that the lotic environments presented greater eutrophication conditions when evaluated by the Toledo Jr. methodology, in which the IETT varied from Eutrophic to Hypereutrophic. However, the evaluated environments showed variations from Mesotrophic to Hypereutrophic for the IETL when evaluated according to the Lamparelli methodology. From the classification proposed by Toledo Jr., lentic water bodies were considered Mesotrophic (IETT > 44) and Hypereutrophic (IETT > 74), while the Lamparelli method classified them as Eutrophic (IETL > 59) and Hypereutrophic (IETL > 67). Concentrations of phosphorus encountered in all water samples were greater than the limits established by the CONAMA Resolution n. 357, 2005, for class 2 water bodies, probably due to the discharge of untreated domestic and industrial wastes into the waters.

Author Biographies

Ronaldo Fia, Universidade Federal de Viçosa
Engenheiro Agrícola e Ambiental, DSc. Engenharia Agrícola (Recursos Hídricos e Ambientais)
Antonio Teixeira de Matos, Universidade Federal de Viçosa
Engenheiro Agrícola, D.Sc. Professor do Departamento de Engenharia Agrícola da UFV
Paulo Carteri Coradi
Engenheiro Agrícola, UFPEL, Doutorando em Engenharia Agrícola, UFV
Orlando Pereira-Ramirez
Engenheiro Químico, D.Sc. Professor do Departamento de Engenharia Agrícola da UFPEL
Published
23/04/2009
Section
Papers