Impacto ambiental de elementos-traço em solos adubados com fertilizantes fosfatados e lodo de esgoto em longo prazo

Abstract

The intensification of food production has been necessary in recent years to cope with the increasing demand caused by a world population growth and changes in food consumption patterns. To meet this new demand for food, some products such as chemical and organic fertilizers have been used in order to increase crop yields. Yet, it is necessary to evaluate the quality of these products, as well as the effects of their long-term applications in order to ensure global food security. Although they are used for the purpose of supplying plant nutrients, some of these fertilizers may contain contaminants with a potential for ecosystems pollution and degradation. Among these contaminants are some trace elements (ETs), which are able to cause deleterious effects to many forms of life – including humans – even if present in small concentrations in the environment. This study evaluated the potential for environmental contamination caused by selected ETs following a continued use of sewage sludge and phosphate fertilizer (single and triple superphosphate) on Brazilian agricultural soils. The investigation was conducted under field conditions in agricultural areas located in Rondonópolis (a study comprising phosphate fertilizer application for 8 years in the state of Mato Grosso) and Jaboticabal (a study involving long-term soil application of sewage sludge, for 15 years, in the state of São Paulo). We assessed distribution coefficients and plant uptake factors in order to evaluate the mobility and availability of As, Cd, Pb, Cu, and Zn in the soil. Results showed that the continued use of phosphate fertilizer and sewage sludge caused changes in fate and mobility of the ETs in the soil, with Cd being more mobile and potentially toxic than other elements evaluated in both experiments. The mobility of As in the soil increased due to phosphate fertilizer applications, while the application of sewage sludge as a fertilizer increased the mobility and availability of Cu, Pb, and Zn.