Updating the perception of glyphosate’s occurrence in Colombia: a case of high concentrations in a natural reserve in the eastern savannah plains

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Updating the perception of glyphosate’s occurrence in Colombia: a case of high concentrations in a natural reserve in the eastern savannah plains

Carlos Manuel Guío Blanco, Eduardo Quintero Chavarría

Glyphosate has been aerially sprayed in Colombia since decades for the purpose of illicit crop eradication and weed control. Although the most recent illicit crop eradication plan (PECIG) was halted in 2015, its reactivation is being currently attempted by the National Police Anti-Narcotics Directorate, on the grounds of glyphosate’s allegedly innocuous nature, low environmental mobility, and well documented practices in Colombia’s agroindustry. The lack of glyphosate environmental fate studies in Colombia suggests otherwise. The independent assessment presented here aimed to provide support to low-cost spectrophotometry for glyphosate monitoring, to document the occurrence of glyphosate within a natural reserve, and to provide a preliminary understanding of factors that influence glyphosate dispersion in overflow-savannah soils. Our research site serves as a case study to understand contamination risks to protected areas, regardless of the purpose of glyphosate application. The results show that short-range soil variability conditions a complex distribution of surface and subsurface water pockets, between which glyphosate transport happens. We found concentrations between 0.25 and 2.2 ppm in water samples at eight locations in the natural reserve; four of them in saturated soil horizons at ca. 1 m depth, three among them located at ca. 500 m inwards from the reserve’s boundaries. High glyphosate concentrations are related to anomalous sulfate, phosphate, nitrate and ammonium contents in the water. These findings highlight the relevance of independent monitoring to update the perception of glyphosate’s environmental impacts in Colombia, and argue for data-based regulatory frameworks and procedures, e.g. in relation to the width of buffer protection zones, and to the inclusion of more comprehensive approaches in monitoring programs, which should take into account -on a case-by-case basis- hydropedological complexities.

Keywords: Glyphosate; Colombia; natural reserve; independent assessment; soils and water; spectrophotometry

Proscience vol. 7

Pp 47-54

DOI: 10.14644/ghc2020.008