Comparative Effects of Technical-Grade and a Commercial Formulation of Glyphosate on the Pigment Content of Periphytic Algae

Abstract

We investigated the potentially different effects of one of the most commonly used glyphosate formulations in Argentina, Glifosato Atanor, and the technical-grade glyphosate on the pigment content, as biomass indicators of the algal fraction in a freshwater periphytic community. A laboratory bioassay was carried out in 250-ml beakers. Two treatments were used: technical-grade glyphosate acid and Glifosato Atanor (isopropylamine salt of glyphosate 48 % w/v), which were at a concentration of 3 mg active ingredient per liter. Treatments and the control (without herbicide) were replicated in triplicate. The concentrations of chlorophyll a and b and carotenes were determined at 0, 2, 6, 10, 24, 48, 96 and 192 h after herbicide addition. A significant increase in pigment content was observed for both herbicides after a 2-day exposure. Moreover, the formulation had little or no effect compared to the active ingredient, suggesting that the additives of Glifosato Atanor may not enhance glyphosate toxicity.