Herbicides such as glyphosate have been widely used in agriculture for several decades, and their occurrence in surface waters has been documented worldwide. However, information on the seasonal variability and occurrence of glyphosate in tropical coastal river systems remains limited, particularly in regions of the Gulf of Mexico. The present study aimed to quantify glyphosate concentrations in surface water from the Jamapa river (Veracruz, Mexico) during dry and rainy seasons and to evaluate their temporal variability and regulatory relevance. Three sampling campaigns were conducted in 2022 (May, June, and July), and glyphosate was analyzed using a competitive enzyme-linked immunosorbent assay (ELISA). Glyphosate was detected in all samples, with mean concentrations of 1.32 µg L⁻ 1 in May (dry season), 0.15 µg L⁻ 1 in June, and 3.7 µg L⁻ 1 in July (rainy season), showing statistically significant seasonal differences ( p < 0.05). Concentrations exceeded the European drinking water guideline (0.1 µg L⁻ 1 ) but remained below Mexican and other international regulatory limits. These results provide baseline information on the occurrence and seasonal behavior of glyphosate in the Jamapa River and highlight the importance of continued monitoring of emerging contaminants in tropical river basins influenced by agricultural activities.
Fernández-Peña et al. (Tue,) studied this question.