In sugarcane crops, several agricultural pesticides are applied simultaneously, and a set of these can be detected in groundwater and surface waters, characterizing a contamination by pesticides mixtures with different concentrations in these bodies of water. Thus, the aim of this work is to estimate the gray water footprint of the pesticide mixture (herbicides) used in a dystrophic Yellow Ultisol in a sugarcane cultivation system, in Pernambuco, Brazil, based on the toxicity of each pesticide used in the mixture. For this objective, the model proposed by Paraiba et al. (2014) was used, where the gray water footprint is determined by physicochemical characteristics of the soil and pesticides, the pesticide application rates (dose), and the lowest value of the effective mean dose of these substances in a population of organisms (EC50). The gray water footprint of the pesticide mixture was 1.32
۱۰۵ m3 ha1 . The highest volumes of gray water and higher ranks of the mixture were due to Amicarbazone and Hexazinone, with 1.05
۱۰۵ m3 ha1 (r ¼ ۵) and 3.71
۱۰۴ m3 ha1 (r ¼ ۴٫۶), respectively, and the lowest values were due to Paraquat and Glyphosate, with gray water footprint of 1.64 and 8.43 m3 ha1 , respectively. The gray water footprint for the yield of the sugarcane crop was estimated at 1731.1 m3 t 1 , considered a high value for the gray water footprint of the sugarcane, demonstrating how much this crop can demands water resources to dilute its load of contaminants.

Introduction

There is currently a strong and unavoidable commitment to protecting water and its natural characteristics, as well as the fulfillment of human needs, such as: obtaining food in quantity and quality, fibers, fossil fuels, biofuels and biomass, industry, among others. Moreover, the global production of biological energy resources is expanding and accelerating the growth of agricultural production. As a consequence of these demands, water scarcity represents a major commercial and environmental concern worldwide (Popp et al., 2014). In the agricultural sector, the increased use of technology to produce food, fiber and fuel, for example, has contributed greatly to the productivity gains of agricultural crops (Brodt et al., 2011). However, the inappropriate use of these same technologies as, for example, pesticides, could jeopardize the developments observed in the Agricultural sector (Damalas and Eleftherohorinos, 2011). About the sugarcane culture, Brazil is the world’s largest sugarcane producer, being responsible together with India, for more than half of the production of this commodity on the world. Despite the relevance of the sugarcane crop and its economic results for Brazil in terms of trade balance and also GDP, it is necessary to take into account the environmental aspects resulting from the cultivation of this crop. Studies have shown that the sugarcane crop has negatively impacted the environmental compartments, as well as its biotic and abiotic components (Liboni and Cezarino, 2012; Pignati et al., 2017).