Identificação de contaminação de solo em área vitícola: avaliação preliminar e investigação confirmatória

Abstract

Soil contamination by metals, resulting from successive applications of pesticides and fertilizers in viticultural áreas, affect the productivity and biodiversity of ecosystems, allowing the leaching of these substances in groundwater. Since there is a possibility that viticultural areas may be contaminated by metals because they have received pesticide and fertilizer applications for decades, this study aimed to perform the identification step proposed by the Brazilian legislation CONAMA Resolution nº 420/2009. By Preliminary Assessment and Confirmatory Investigation provided in NBR 15515/2011, parts 1 and 2, was sought to prove the existence of possible contamination and propose techniques for minimizing contaminants in a rural area of the city of Bento Gonçalves/RS. Thus, the area was evaluated considering information about its history of use through an interview with the person in charge; characteristics of the physical environment; pesticides used on the farm through consultation of record books; concentrations of the metals chromium (Cr), nickel (Ni), copper (Cu), zinc (Zn), and cadmium (Cd) through soil sampling at three points on the property (P1 between the forest and the plantation; P2 in a 50-year-old cultivated area; and P3 a 20-year-old cultivated area); and also, remediation actions were proposed for three scenarios. The analyzes were done by acidic digestion and determined via Optical Emission Spectroscopy with Inductively Coupled Plasma (ICP-OES). The results showed that the sites with potential for contamination are close to concrete tanks used for manual mixing of grouts, as well as close to sheds where grouts are currently stored, handled, and prepared to be mechanically sprayed. Soil analysis showed that the soil located in a 20-year-old cultivation area (P3) is classified as Class 3 since Ni and Cr concentrations exceed the "Prevention" values established by legislation, while the soils of the other points (P1 and P2) are classified as Class 2. The proposed scenarios contemplated: (1) actions to decrease contamination with the presence of agricultural activity, (2) mitigation and natural regeneration with the absence of agricultural activity, and finally, (3) the electrokinetic technique was indicated for remediation. The conclusion is that the soil analyzed is not contaminated, however, actions are needed to reduce the concentration of contaminants so that the values of "Investigation" and Class 4 are not reached, not compromising the environmental quality, the planting, and the health of farmers. [resumo fornecido pelo autor]