Avaliação dos efeitos da contaminação por Cd e Pb na alface (Lactuca sativa L.) hidropônica empregando métodos de reconhecimento de padrões não supervisionados: PCA e HCA

Abstract

A greenhouse assay using a lettuce (Lactuca Sativa) hydroponics system was carried out to evaluate the following effects of contamination by cadmium (Cd), (article 1), and by lead (Pb), (article 2): 1) evaluate the effects of increasing doses of Cd (0,000; 0,025; 0,100; 0,500 e 1,000 mg L-1) and Pb (0,00; 0,25; 1,00; 5,00 e 10,00 mg L-1) on the contents and accumulation of nutrients; 2) evaluate possible mechanisms to Cd and Pb detoxification, employing chemometric tools: principal components analysis (PCA) and hierarchical clusters analysis (HCA) models. PCA In articles 1 and 2, the K get high mobility and dry matter by lettuce is not change with dosages. Most chemical elements concentrated in roots, excluding the Ca for Cd and Pb, and Mg for Pb; the increasing dosages of Cd was antagonistic for levels of Ca, Mg, Mn, and Zn and synergism for N and Cu; the Pb proved to be antagonistic for Ca and Mg, and synergism for N, S and P. In accumulation, the Pb was more estatic as Cd, concentrated in roots; Pb and Cd were synergisms for S and antagonistic for Fe, Cu, and Mn. HCA: Additional results not provided to the PCA method, for two heavy metals. The PCA model was sufficiently effective in any conclusions.