Evaluación de la incidencia del oxígeno disuelto en la concentración de nutrientes en el río Pachanlica de la provincia de Tungurahua

Abstract

The present research evaluated the influence of dissolved oxygen on nutrient concentration at Pachanlica river placed in Tungurahua province. Fourteen monitoring points were established along the river channel, considering its morphometric and hydrometric characteristics. During August to November 2023, 28 water samples were analyzed, measuring physicochemical parameters. In addition, nutrient hydrodynamics and vulnerability analysis were estimated by calculating the Water Quality Risk Index (%IRCA) and the Pollution Hazard Index (CPI). Finally, the relationship between dissolved oxygen and nutrients was examined using Spearman's correlation. According to hydromorphometry, the selected monitoring points differed in their variability in slopes and location in areas with and without anthropogenic influence. The hydrodynamic analysis revealed a greater movement of nutrients during the transition to rainfall compared to the dry season, especially from points RP10 to RP14. Higher flows of 392.1 kg/h of nitrates, 19.05 kg/h of nitrites, and 346.3 kg/h of phosphates were recorded. The vulnerability analysis indicated a higher risk of river water use in the points located in the middle-lower part of the micro-watershed, considering them unviable for human use and consumption. Finally, the correlation analysis showed an inversely proportional relationship between dissolved oxygen and nutrients, highlighting during the dry season a decrease in dissolved oxygen and an increase in nitrate and nitrite concentration. This correlation that has repercussions on water quality, making it riskier for humans. It is suggested to implement environmental actions to regulate the entry of nutrients into the micro-watershed and thus reduce pollution and preserve the resource.