Extraction and plant availability of zinc and lead in a latosol amended with steel industry residues

Abstract

Zinc and lead are trace elements of major environmental concern, as they can originate from point and non-point polution sources and bioacumulate in food webs, with potential risk to human health. Steel industries produce large amounts of residues that may contain Zn and Pb, and the effect of disposing these materials in the environment is little studied in Brazil. This work aimed to select different chemical extractants (water, Mehlich-1, diethylene triamine pentacetic acid - DPTA, citric acid, and concentrated nitric acid) to estimate Zn and Pb availability to elephant grass and common beans. Three different residues (steel slag, filter-press mud and phosphate mud) in five doses (0, 1, 2, 4 and 8 Mg ha-1) were added to a Latosol. Water-soluble Zn comprised a significant part of the total, suggesting its higher solubility and potential contamination of soil, water and plant, when compared to Pb. Pearson correlation coefficients between Zn in plant and soil, for all extractors, were generally higher than for Pb. The correlation coefficients of Zn and Pb levels in soils and plant tissues varied with time and extractor, and DPTA was the most adequate for both elements.