Nitrates and phosphates concentration in the Cesar river between Zambrano (La Guajira) and las Pitillas (Cesar)
Contextualization: Anthropogenic activities influence the nitrogen and phosphorus cycle in surface waters, being a significant environmental problem.
Knowledge gap: At present, there is no research that addresses the study of NO3- (Nitrates) and PO43- (Phosphates) ions by spectrophotometric methods in the Cesar River basin (Colombia).
Purpose: This research studied the concentrations of NO3- and PO43- in the Cesar River, between Zambrano and Las Pitillas, during rainy (September 2022) and dry (January 2023) seasons, in areas with grazing, agricultural and domestic activities, to evaluate the Nutrient Pollution Index (NPI).
Methodology: Spectrophotometric methods were used to detect NO3- and PO43-.
Results and conclusions: NO3- concentration ranged between 0.460 ±
± 0.044 mg.L-1 at San Juan and 1.182 ±± 0.032 mg.L-1 at Salguero in the rainy season, while in the dry season it fluctuated between 0.936 ±± 0.151 mg.L-1 at Zambrano and 1.865 ± 0.150 mg.L-1 at Las Pitillas.
As for PO43-, values ranged between 1.514 ± 0.022 mg.L-1 at San Juan and 2.739 ± 0.022 mg.L-1 at Salguero in the rainy season, while the dry season ranged between 2.405 ± 0.156 mg L-1 in San Juan and 5.553 ± 0.143 mg.L-1 in Salguero. Compared with the limits established by the World Health Organization (WHO, 2004), only in Salguero (5.553 ± 0.143 mg.L-1) exceeded the permissible value for PO43- during the dry season. Finally, the NPI indicated moderate pollution in Salguero during the dry season.