Analysis of pesticide residues in the surface water of the Ayuquila-Armeria river watershed, Mexico

Abstract

The application of chemical products for pest control is one of the most widely used methods in agriculture worldwide despite their adverse effects on humans and the environment. This is a topic of interest due to the growing number of chemical products and their toxicity. The objectives of this research were to identify the most commercialized pesticides in the Ayuquila-Armería River basin (Mexico) and to determine their concentration in the surface water of the basin. The hypothesis of this work was that the current system of agricultural production in the basin is causing degradation of water quality due to the presence of a wide variety of pesticides. For the f irst objective, we visited 27 outlets of pesticides located in the main municipal capitals within the basin, obtaining a total of 143 commercialized active ingredients, mainly of chemical origin. For the second objective, we carried out two samplings in the dry season and two in the rainy season, in 30 sites distributed within the basin. The sampling sites were chosen in a directed way according to the problem of existing contamination and trying to cover the largest agricultural areas within the basin. The analyses were carried out through liquid chromatography coupled to mass-mass spectrometry. The results showed that 66% of the samples contained at least one pesticide. The most frequent pesticides were ametrine, dimethoate and diazinon. The sites that presented the highest number of pesticides in the four samplings were Palo Blanco, Antes Manantlán, Tuxcacuesco and Ayuquila. The sites near the area of intensive agriculture had a higher number of pesticides than those located in areas with rainfed agriculture. This study is the f irst to analyze the presence of pesticides in surface waters of the basin.