Teores de Metais - traço em solo do Parque da Jaqueira localizado no munícipio de Recife- PE

Abstract

The study of geochemical phases is very important because the analysis of total metals does not reflect the reality of the impact on the environment. Metal speciation studies (performed by sequential extraction) are due to the fact that small changes in the bioavailability of metals and environmental conditions can make them toxic to plants and animals. Knowledge of these forms and their chemical bonds in soils helps to identify specific sources of pollution. The geochemical phases are exchangeable, leachable, reducible, oxidizable, and pseudo-residual. Each phase is extracted by a specific extractant, namely: magnesium chloride, acetic acid, hydroxylamine hydrochloride, hydrogen peroxide, and aqua regia. The objective of the study was to analyze the bioavailability of trace metals in Jaqueira Park, located in the Jaqueira neighborhood in the North Zone of the city of Recife. The soil samples collected at the Jaqueira Children's Park were dried in an oven, crushed, sieved and weighed. After sequential extraction, the samples were analyzed in an AAS (Atomic Absorption Spectrophotometer) to determine the concentrations of Mn and Fe (considered major) and Zn and Cu (considered minor). In general, the bioavailability of the soil demonstrated the presence of metals mainly in the oxidizable phase, followed by the reducible and leachable phases, although some were also found in the exchangeable phase in lower concentrations. Zinc presented the highest concentrations in the reducible phase, for being bound to Fe and Mn oxides. This phase is also considered bioavailable, and changes in aeration conditions would make this metal available to plants and animals, since the first three geochemical phases are said to be bioavailable. The metal Mn was also found, preferentially, in the reducible and oxidizable phases. The degradation of humic substances from the soil can mobilize this metal and the same can happen with the chemical element – Iron, consequently affecting plants, animals and even human health.