Pesticides in water and sediments of Chacahua-Pastoria Lagoon System, Oaxaca, Mexico

This is the first report about the presence of pesticide residues in water and sediments from Chacahua-Pastoria Lagoon System in the Oaxaca Coast, Mexico. Organochlorine and organophosphate pesticides were analyzed in water and sediment samples collected during rainy and dry seasons in 2018. The pesticides extraction was carried out by 525.2 EPA and QuEChERS methods for water and sediments samples, respectively. The quantification was done by gas chromatography coupled to electron microcapture (μECD) and flame photometric (FPD) detectors. Univariate and multivariate analysis were carried out to evaluate the distribution patterns, comparing between lagoons, seasons and matrices. The spatial distribution of malathion and organochlorines in water showed the highest values near to adjacent land with some patterns differences. DDT was the most frequent in water and sediments samples, showed the highest concentrations in the Pastoria Lagoon. These results indicate the need to establish a permanent monitoring programs to implement mitigation measures. •Pesticide residues were presented in water and sediments of the Chacahua-Pastoria lagoon system in Oaxaca, Mexico.•The pesticide distribution patterns were different comparing between lagoons, seasons and matrices.•DDTs was the most frequent compounds in water and sediments samples, with the highest concentrations in the Pastoria Lagoon.•These results indicate the need to establish a permanent monitoring programs to implement mitigation measures.