Comparative study of metal contents in Brazilian coffees cultivated by conventional and organic agriculture applying principal component analysis

摘要

The aim of this study was to evaluate of availability of nutrients and toxic elements in green coffees produced in traditional, technological and transitional organic farms in Southwest Bahia-Brazil. Levels of the nutrients minerals were determined directly in samples of soils and coffee tissues from four farms by flame atomic absorption spectrometry (FAAS) and toxic elements (Cr, Ni, Cd and Pb) by inductively coupled plasma optical emission spectrometry (ICP OES). The application of statistical methods (cluster and principal components analysis) revealed the importance of the conversion period to guarantee a product genuinely organic during the change to organic agriculture. On the other hand, the study of correlations between agricultural methods and metals concentrations in coffee suggested that Cd, Cu, Zn and other toxic elements contained in some inorganic fertilizers used in the traditional and technological coffee farms may cause an increase of toxic metals concentration in the crop soil, be taken up by plants, and passed on in the food chain.