Study on the interaction of heavy metals on farmland in Petrópolis, Rio de Janeiro, Brazil.

The contamination of soil and groundwater as a result of the mobility of elements used in farming is of major concern. This paper will present and analyze results of a study aiming to evaluate the mobility of Zn, Cu and Cd contained in NPK fertilizers and simple super phosphate, used on a toposequence formed by a latossol and a podzolic soil. The A and B horizons were analyzed in four different locations of the toposequence. The studied area consists of latossols and podzolic soil profiles (A and B horizons) located on the Marambaia Farm, Petropolis, Rio de Janeiro, Brazil. A tropical climate prevails in this mountainous area, with heavy rains being mostly concentrated within the months of November and March. Undisturbed samples of the soils were collected in the field and submitted, in laboratory column experiments, to infiltration by solutions of Zn, Cu and Cd, under concentrations representing the amount of these elements in fertilizers sprayed on the site. This procedure allowed the evaluation of transport parameters that describe the migration of chemical species through porous media under controlled conditions in the laboratory. The leachate collected from each experiment was analyzed by flame atomic absorption spectrometry to determine their metal concentration. The results showed that metals were retained in the superficial horizons of the soils. Due to superficial erosive processes that occur in the area, it can also be concluded that the metals could be leached from the soil and dispersed by nearby rivers.