Water polluted with glyphosate formulations: effectiveness of a decontamination process using Chlorella vulgaris growing as bioindicator

Abstract

The environmental pollution caused by pesticides is considered a major problemworldwide. Glyphosate is one of the herbicides most widely used, and its use hasincreased sharply in the last years. In this work the toxicity of four commercial glyphosate formulations (Eskoba®, Panzer Gold®, Roundup Ultramax® and Sulfosato Touchdown®) was assessed by determining the median effective concentration at 96 h (96 h-EC50) using the microalgae Chlorella vulgaris as the biological model. Although the formulations tested are moderately to slightly toxic to C. vulgaris according to the World Health Organization´s toxicity categories for aquatic and terrestrial organisms, this research shows that the four formulations are toxic, being Eskoba® the least toxic and Roundup Ultramax® the most toxic one. On the other hand, a UV/H2O2 remediation process for the detoxification of the samples was tested. Its effectiveness was evaluated using a C.vulgaris growth inhibition test. Growth inhibition of C. vulgarisdid not reach 18.2 %, indicating the efficacy of the UV/H2O2 remediation process to reduce glyphosate toxicity. In some of the samples tested within the first 48 h of the assay, C. vulgaris growth was even encouraged. The results of the present work suggest that the selected species was a good indicator to determine glyphosate formulations toxicity level, and shows the relevance of the ecotoxicological tests to evaluate a physicochemical remediation process.