Determinação de nutrientes minerais e contaminantes em macroalgas marinhas para avaliação do potencial uso como fertilizante

Abstract

Fertilizers are classified by Brazilian legislation as mineral (inorganic) or organic and natural or synthetic, whose composition provides at least one nutrient for plant development. As an example of sources of natural fertilizers, marine macroalgae that are naturally deposited on beaches have been the focus of study by the scientific community, since anthropogenic actions and climate change have contributed to the accelerated growth and increase of different macroalgae on urban beaches. In this sense, the objective of this work was to determine Al, As, Ba, Ca, Cd, Co, Cr, Fe, K, Mg, Mn, Na, Ni, Fe, Pb, Se, V and Zn by optical emission spectrometry with inductively coupled plasma (ICP-OES) in the macroalgae Sargassum sp, Ulva compressa and Caulerpa racemosa collected on the urban beaches of Maceió (Ipioca and Pajuçara) to evaluate their potential as fertilizer. In general, the ash content of the macroalgae Sargassum sp and Ulva compressa ranged from 24.6 to 39.0%, respectively. The determination of the elements Cd, Co, Pb, Se and V in the macroalgae was below the limit of quantification and the remosa ursorpa proved to be a greater Na accumulator when compared to the other macroalgae. From the results, it was possible to assess that macroalgae have similar elemental composition profiles, regardless of the collection point, except for the Fe content (2,440 mg/Kg) in Ulva compressa on Pajuçara beach. Furthermore, Sargassum sp showed higher levels of Ba and As and Ulva compressa of Cr and Ni, which corroborates these macroalgae species as environmental bioindicators of these elements. Therefore, the marine macroalgae studied have potential as sources of inorganic nutrients in the form of fertilizer when they are not contaminated by metals with high toxicity potential.