Behavior simulation of nitrogen compounds in rivers with uncertainty analysis

  • Tatiana Candeia da Silva Fortunato Núcleo de Educação Ambiental. Instituto Federal de Educação, Ciência e Tecnologia do Espírito Santo (IFES - Campus Aracruz), Avenida Morobá, n° 248, CEP: 29192-733, Aracruz, ES, Brazil.
  • José Antonio Tosta dos Reis Departamento de Engenharia Ambiental. Universidade Federal do Espírito Santo (UFES), Avenida Fernando Ferrari, n° 514, CEP: 29075-910, Vitória, ES, Brazil
  • Antonio Sérgio Mendonça Departamento de Engenharia Ambiental. Universidade Federal do Espírito Santo (UFES), Avenida Fernando Ferrari, n° 514, CEP: 29075-910, Vitória, ES, Brazil.
  • Fernando das Graças Braga da Silva Instituto de Recursos Naturais. Universidade Federal de Itajubá (UNIFEI), Avenida BPS, n° 1303, CEP: 37500-903, Itajubá, MG, Brazil.
Keywords: monte carlo method, stochastic modeling, uncertainty analysis, water quality

Abstract

  

This study simulated nitrogen-compound concentration changes in rivers, taking into account uncertainty analysis carried out by the Monte Carlo Method. The study area is the final stretch of the Piracicaba River, located in Minas Gerais, Brazil, which is an important Doce River tributary. The uncertainty analysis took into account random generation of hydrodynamic variables, initial water quality conditions and kinetic constants. Different variation percentages for the organic nitrogen decay kinetic constants random generation did not influence considerably the ammonia or organic nitrogen maximum concentration extreme values. In the simulations, maximum organic nitrogen concentrations were most frequently between 0.20 mg.L-1 and 0.22 mg.L-1 (42%), maximum ammonia nitrogen between 0.28 mg.L-1 and 0.30 mg.L-1 (30%), maximum nitrite between 0.05 mg.L-1 and 0.07 mg.L-1 (49%) and  maximum nitrate between 0.46 mg.L-1 and 0.50 mg.L-1 (37%). Estimated maximum concentrations for ammonia nitrogen, nitrite and nitrate did not exceed the environmental quality standards established by Brazilian CONAMA Resolution 357/2005 for Class 2 watercourses. Random generation of kinetic constants that regulate ammonia and nitrite decay produced significant ammonia nitrogen, nitrite, and nitrate peak concentrations value frequencies, histograms and forms changes, when considering variation percentages equal to or greater than 50%. Some simulation results showed more inhibition of oxidized nitrogen forms production.


Author Biographies

Tatiana Candeia da Silva Fortunato, Núcleo de Educação Ambiental. Instituto Federal de Educação, Ciência e Tecnologia do Espírito Santo (IFES - Campus Aracruz), Avenida Morobá, n° 248, CEP: 29192-733, Aracruz, ES, Brazil.
      
José Antonio Tosta dos Reis, Departamento de Engenharia Ambiental. Universidade Federal do Espírito Santo (UFES), Avenida Fernando Ferrari, n° 514, CEP: 29075-910, Vitória, ES, Brazil
     
Antonio Sérgio Mendonça, Departamento de Engenharia Ambiental. Universidade Federal do Espírito Santo (UFES), Avenida Fernando Ferrari, n° 514, CEP: 29075-910, Vitória, ES, Brazil.
    
Fernando das Graças Braga da Silva, Instituto de Recursos Naturais. Universidade Federal de Itajubá (UNIFEI), Avenida BPS, n° 1303, CEP: 37500-903, Itajubá, MG, Brazil.
   
Published
15/05/2020
Section
Papers