Abstract

MOLINA-MORALES, Yuri et al. Pesticide levels in superficial waters of an agricultural region in Mérida state, Venezuela, between 2008 and 2010. Rev. Int. Contam. Ambient [online]. 2012, vol.28, n.4, pp.289-301. ISSN 0188-4999.

The strong demand for agricultural production has led to an indiscriminate use of agro-chemicals causing the decline in the quality of surface waters. In the agricultural com-munity of Bailadores, Municipality of Rivas Davila, Mérida State, Venezuela, the rivers of Las Tapias, Las Playitas and Mocoties were monitored for the presence of pesticide residues during 2008 and 2010. Water samples were subjected to solid phase extraction and analyzed for the presence of pesticide residues by HPLC with diode array detector (SPE-HPLC-DAD) using a validated multiresidual method. The pesticide residues that were detected at higher frequencies and greater concentrations were the following: chlor-pyrifos (302.9±0.9 μg/L), diazinon (459±4.0 μg/L), dimethoate (55±3.0 μg/L), mancozeb (108±1.0 μg/L) and methamidophos (107±8.0 μg/L), which are all found in the list of highly dangerous pesticides by the International Pesticides Control Network. In all cases, the levels exceeded the limits set by the European Union and the Environmental Protection Agency of the United States. The total concentration of organophosphates also exceeded the limits established by the Venezuelan law. The results of this study demonstrate a high level of pesticide contamination of the principal surface water courses in the Municipality of Rivas Dávila. It is recommended to implement a pesticide monitoring program and the need to change the current mode of production to a sustainable agricultural practice, which will allow to reduce the use of agrochemicals and their negative consequences to the environment and the human health.

Keywords : superficial waters; pesticides; SPE-HPLC-DAD; Mérida-Venezuela.

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