Estabelecimento dos valores de referência de qualidade para os solos da bacia hidrográfica do rio Jaboatão

Abstract

The establishment of Quality Reference Values (QRV) is essential to prevent and determine the state of soil contamination. Although there are already studies to determine these values in several places in Brazil, the great lithological variability justifies the need for more detailed approaches. In this context, the objective was to establish the VRQ for Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn in 16 layer samples (superficial 0-0.20 m and subsurface 0.20-0.40 m) of the soils of the Jaboatão river basin in Pernambuco. The "mean + 2 x Standard Deviation (SD)", "median + 2 x Median Absolute Deviation (MAD)", upper whisker of the Tukey boxplot, Percentile 75 and Percentile 90 were used to determine the VRQ. The extraction of the elements took place using the EPA-3050B method and the concentration was determined by atomic absorption spectrometry. According to the results, the trace element levels in the soils of the Jaboatão river basin followed the following descending order: Al, Fe, Zn, Mn, Pb, Cr, Co, Ni, Cu and Cd. Most of the elements studied come from the original material. The average contents of Pb and Zn were higher than those found in soils from other regions of the country, and may have been influenced beyond the composition of the material of origin in the region, by urban centers and by traffic on local highways. Cr, Cu and Ni presented most of the undetected data, so it was classified as lower than the Practicable Quantification Limit. To determine the VRQ, anomalous values were removed. The method of the boxplot upper limit and the "mean + 2 x SD" presented higher values, that is, they overestimated the VRQ, the "median + 2 x SD" presented values closer to the 90th Percentile. However, the 75th Percentile was selected as the appropriate calculation method, as it is more conservative. Since the values of Co, Pb and Zn were higher than the VRQ of Pernambuco, but did not exceed the Prevention Values established by Resolution 420/2009 of the National Environmental Council, ensuring that soils do not present risks to human health and ecosystems in the region.