ASSESSMENT OF WATER QUALITY FROM WIERNA AND MOJOTORO RIVERS IN SALTA, ARGENTINA

LIDIA G PEÑALOZA; HECTOR ANTONIO CRISTÓBAL; SARITA REYES; VERONICA B RAJAL; MARCELO A JURADO; GUSTAVO CELIZ

Salta

Congreso; LV Annual SAIB Meeting and XIV PABMB Congress; 2019

Sociedad Argentina de Buiquimica y Biología Celular

The Wierna and Mojotoro rivers run from north to south crossing La Caldera, in the province of Salta. The Mojotoro river receives the discharge of two wastewater treatment plants. As both rivers are used for recreational purposes, it is important to assess the water quality. The objective of this work was to evaluate the influence of wastewater treatment plants (WWTP) discharges on the physicochemical and microbiological water quality. A total of 90 water samples were obtained from three points (P), one in the Wierna river (P1) and two in the Mojotoro river (P2, P3). Physico-chemical variables were measured in situ: temperature, pH, turbidity, conductivity, salinity, and dissolved oxygen, using a portable multiparameter analyzer. Density of total (TC) and fecal (FC) coliform bacteria was determined in the laboratory using the multiple tube method. The concentrations of Cu, Mn, Pb, Fe, Cr, Zn, and Cd were measured by atomic absorption spectrophotometry (AAS) and that of As by the Hydride Generation method (HG) coupled to AAS. Spearman correlation analysis was performed to search for correlation between variables analyzed and the potential influence of WWTP was evaluated using the Wilcoxon test. The minimum and maximum values of the physico-chemical variables were: 8.5-21°C for temperature, pH 7.8-9.5, and 2 -> 999 NTU for turbidity, 0.19-0.32 mS/cm for conductivity, 0-0.02% salinity, and 2.3-7.7 mg/l of dissolved oxygen. In addition, the range for TC and FC were 0-1.09x106 and 0-1.19x105 NMP/100 ml, respectively. Iron and Mn at P1 and P2 exceeded the maximum permissible limits, established by international legislations (0.2 and 0.1 mg/l, respectively). Correlations between Zn and conductivity, TC and FC were statistically significant (p-value> 0.05). The Wilcoxon test showed significant differences (p-value> 0.05) for TC and FC between P1 and P2, and P2 and P3. The Mojotoro river showed deterioration inwater quality after receiving the discharge of WWTP. High concentrations of bacterial indicators and heavy metals in these sites represents a risk to public health