Dissipation and Adsorption of 2,4-D, Atrazine, Diazinon, and Glyphosate in an Agricultural Soil from Yucatan State, Mexico

Pesticides are used worldwide in farming activities to guarantee crop yields. In southeastern Mexico, groundwater is the primary source of water for humankind. However, because of the soil characteristics and of intensive agricultural practices, the aquifer is vulnerable to pollution as shown by the regular detection of pesticide residues in groundwater. Within this context, the dissipation and adsorption of four of most used pesticides (2,4-D, atrazine, diazinon, and glyphosate) by farmers in southeastern Mexico were studied to determine their fate in agricultural soil and estimate their risk for the aquifer. Forty-one days after their application, the four pesticides were entirely dissipated from the soil. 2,4-D and glyphosate were the most persistent according to DT50. Diazinon was the most adsorbed to the soil at equilibrium time. All pesticides were volatilized in substantial amounts, reaching 10.1, 22.3, 22.4, and 43.4% of initial amount 72 h after application of glyphosate, atrazine, 2,4-D, and diazinon, respectively. Volatilization was dependent on time and pesticide type (P < 0.05). Following their K-OC, diazinon and glyphosate were found to be the most prone to leach. Therefore, in the absence of mitigation measures, their use represents a significant threat for the groundwater in Southeastern Mexico.