Analysis of water quality in the Alseseca River, in Tlapacoyan,Veracruz, Mexico

Abstract

Surface water bodies provide essential ecosystem services, but their quality is increasingly being affected by human activities. In Mexico, information on the impact of leachate generated by open-air municipal landfills on surface water bodies remains limited. The objective of this study was to assess the water quality of the Alseseca River in Tlapacoyan, Veracruz, Mexico, at a point located approximately 200 m from a municipal landfill lacking leachate control infrastructure. The hypothesis was that proximity to the landfill negatively affects water quality by increasing levels of microbiological contaminants and heavy metals. Monitoring was conducted every ten days between January and December 2025, yielding a total of 36 samples. Biological and physicochemical parameters, as well as heavy metals, were analyzed in accordance with current Mexican regulations and the Standard Methods for the Examination of Water and Wastewater. The results showed average concentrations of E. coli exceeding 2 400 MPN 100 mL-¹, surpassing the limits established by NOM-001-SEMARNAT-2021. The physicochemical parameters evaluated remained within national limits, although some values exceeded international reference values. Additionally, arsenic, cadmium, copper, chromium, mercury, nickel, lead, and zinc were detected. The Water Quality Index based on heavy metals classified the water as poor quality. The results suggest a possible influence of landfill leachate on the aquatic ecosystem and highlight the need to strengthen environmental monitoring and management efforts in water bodies near municipal solid waste disposal sites.