Organophosphate Pesticides in Coastal Lagoon of the Gulf of Mexico

Abstract

The worldwide use of semi-persistent organophosphate pesticides has become increasingly frequent and notorious. Their presence is registered in both continental and coastal waters; the latter ones are known for their subtly balanced environmental richness, difficult to recover once lost. These xenobiotics compounds reach the coastal zone through rivers that have crossed human settlements, as well as through peripheral run-off water used to exterminate agricultural pests. In Mexico, a developing country, the use of pesticides for several decades has not been adequately regulated, which is why various coastal ecosystems are the accumulation areas of these agrochemicals used in the continent. In the Gulf of Mexico, one of the coastal systems of high fishing importance for many years is the lagoon of Alvarado and receives the discharges of two great rivers, Blanco, Limón and Papaloapan, which travel more than 200 km from its source to the sea, crossing large extensions of farmland where there are also livestock activities and the use of these pesticides. For this reason, the objective of this work was to determine the presence of organophosphate pesticides in the Alvarado lagoon at the Gulf of Mexico as a potential aspect of high impact contamination. Five pesticides have been identified in the lagoon sediments, of which the most important and highest concentrations are Dimethoate and Chlorpyrifos, with 75.65 - 79.0 ng/g and 0.17 - 0.23 ng/g respectively, both internationally classified as moderately toxic. These concentrations were comparable to levels in other world regions with intense agricultural activity and vector control like the Mediterranean Sea and the lagoon of Alvarado was evidenced as a hot spot for the accumulation of these organophosphates with the high risk for the benthic organisms and for the human health when consuming these fishery products.