SPATIAL ASSESSMENT OF ENVIRONMENTAL CONTAMINATION BY PESTICIDES IN THE MUNICIPALITY OF PETROLINA-PE

Abstract

A way to evaluate the risk of environmental contamination by an agrochemical is to consider its physical and chemical properties in terms of their capacity to associate themselves to the soil, volatilize, lixiviate, solubilize, etc. The GOSS and GUS methods combine such information, allowing us to create a profile of the contaminant, which serves as a basis for assessing the potentiality for contamination of hydric resources on the surface and underground by certain agrochemicals. In this aspect, several tools can be used, for instance those which consider the combination of these and other models associated with the Geographic Information System for mapping regions, in which the characteristics of the soil and hydric resources available allow us to obtain a vulnerability profile in which the different locations are found, particularly the agriculturally productive. The sub-medium region of the Vale do São Francisco is one of Brazil's main centers for producing and exporting fruits, being specialized in the production of grapes and mangoes. The agricultural system implanted in this region requires an evaluation of its impacts on the environment, notably on soil, water and atmosphere, considering the physical, chemical and biological characteristics of local natural resources. Consequently, monitoring and controlling the usage of agrochemicals in this region is still a challenge for environmental inspection departments. This paper sought to evaluate the risk of environmental contamination in the agricultural regions of Petrolina-PE, based on information built from a Geographic Information System, considering physical aspects of the soil and water compartments, highlighting types of soil, potential for hydraulic conductivity and declivity, associated with the physical-chemical properties of the recurrent agrochemicals in 2011. Based on the proposed models (GUS and GOSS), the study revealed a high lixiviation potential for the agrochemicals that undergo lixiviation and, therefore, have high potential of contaminating underground water resources, particularly in the case of Azoxistrobin, Boscalid, Carbendazim, Dimetomorph, Fenarimol, Methomyl, Myclobutanil  and Thiamethoxam. On the other hand, composites such as Cyproconazole, Difenoconazole (1,2), Propargite and Tebuconazole displayed high potential for contaminating surface waters. Therefore, the agrochemicals that can be lixiviated must be avoided in soils of high hydraulic drainage, as well as in soils of relative declivity which will transport them to surface hydric resources. The combination of data about the vulnerability of soils with properties of the agrochemicals has highlighted that it is possible to point out, preliminarily, contamination regions for different agrochemicals in the municipality of Petrolina. The combination of spatial data with chemical knowledge can point towards more rational practices in which culture/environment/agrochemicals must be considered as a set that establishes interrelations.