A comparison of pesticide residues in soils from two highly technified agricultural valleys in northwestern Mexico

Abstract

A pesticide characterization is presented for two highly technified valleys in northwest Mexico: Culiacan Valley (CV) in Sinaloa and Yaqui Valley (YV) in Sonora. Approximately 250,000 kg of active ingredients are used every year, half of which are considered highly hazardous pesticides. Legacy pesticides are still present in the soils of these valleys. The aim of the present study was to identify and quantify a wide variety of pesticides in soils and correlate their concentrations with historical and current use. Agricultural soils from both valleys were sampled and analyzed using accelerated solvent extraction and subsequent quantification by gas chromatography with selective detectors. The most frequently detected pesticides (mean, µg g⁻¹) in CV were organochlorines (0.1967), organophosphates (0.0928), synthetic pyrethroids (0.2565), organonitrogen (0.0552), and miscellaneous pesticides (0.1851). In YV, the most frequently detected pesticides were organochlorines (0.8607), organophosphates (0.0001), synthetic pyrethroids (0.0124), and miscellaneous pesticides (0.0009). The pesticides were more diverse in CV compared to those of YV, which was based on the types of crops produced. Both locations presented highly hazardous pesticides, including concentrations above the action levels established by the Canadian Soil Quality Guide. A follow-up risk assessment is recommended to assess potential effects.

Keywords:

• Culiacan Valley
• Yaqui Valley
• organic pollutants
• pesticides

Acknowledgments

The present study was possible due to an environmental research grant [number S0010-2008-1] awarded by SEMARNAT (Secretaría de Medio Ambiente y Recursos Naturales)-CONACYT (Consejo Nacional de Ciencia y Tecnología) to MBL [project number 107598]. A CONACYT scholarship was granted to JBLM for PhD studies. We would like to thank the members of the National Laboratory for Food Safety Research (LANIIA) of CIAD (Centro de Investigación en Alimentación y Desarrollo A.C.) Culiacan for their assistance with both laboratory and field work.