Use of nuclear technique in samples for agricultural purposes

Abstract

ABSTRACT:The concern related to environment is growing. Due to this, it is needed to determine chemical elements in a large range of concentration. The neutron activation technique (NAA) determines the elemental composition by the measurement of artificial radioactivity in a sample that was submitted to a neutron flux. NAA is a sensitive and accu rate technique with low detection limits. An example of application of NAA was the measurement of concentrations of rare earth elements (REE) in waste samples of phosphogypsum (PG) and cerrado soil samples (clayey and sandy soils). Additionally, a soil reference material of the International Atomic Energy Agency (IAEA) was also analyzed. The REE concentration in PG samples was two times higher than those found in national fertilizers, (total of 4,000 mg kg -1 ), 154 times greater than the values found in the sandy soil (26 mg kg -1 ) and 14 times greater than the in clayey soil (280 mg kg -1 ). The experimental results for the reference material were inside the uncertainty of the certified values pointing out the accuracy of the method (95%). The determination of La, Ce, Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb and Lu in the samples and reference material confirmed the versatility of the technique on REE determination in soil and phosphogypsum samples that are matrices for agricultural interest.KEYWORDS: neutron activation analysis, multielemental analyses, phosphogypsum, rare earth elements. USO DE TÉCNICA NUCLEAR EM AMOSTRAS DE INTERESSE NA AGRICULTURA RESUMO:A preocupação crescente com o meio ambiente leva à necessidade de serem determinados elementos químicos em faixas de concentração cada vez mais largas. Entre as técnicas existentes, está a ativação neutrônica (AAN), que determina a composição química elementar por meio da medida da radioatividade artificial induzida ao se submeter uma amostra a um fluxo de nêutrons. A AAN possui alta sensibilidade, exatidão, precisão e natureza não destrutiva (dispensa tratamento químico prévio). Como exemplo de aplicação da técnica, elementos terras raras (ETR) foram determinados em amostras do resíduo fosfogesso (PG) e de solo do cerrado (argiloso e arenoso). Adicionalmente, um material de referência de solo da Agência Internacional de Energia Atômica foi analisado. A concentração de ETR no PG foi, em média, duas vezes maior que a encontrada na maioria dos fertilizantes nacionais (total de 4.000 mg kg -1 ), 154 vezes maior que no solo arenoso (26 mg kg -1 ) e 14 vezes maior que no solo argiloso (280 mg kg -1 ). Os resultados obtidos no material de referência confirmaram a exatidão do método com intervalo de confiança de 95%. Foi comprovada a versatilidade da técnica ao serem determinados o La, Ce, Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb e Lu em amostras de solo e fosfogesso de interesse na agricultura.

Performance Test of K₀-NAA and Relative Method for Analysis of Al, Mg, K Nuclides in SRM Lake Sediment Sample

“…Air pollution monitoring concerns the determination of the incidence, elemental composition, and size of aerosol particles in the ambient or indoor air, or studying the above parameters in combustion aerosols, which are the main source of air pollution [3]. Also NAA is used to determine of aluminium, silicon and magnesium in geological matrices [4] and rare earth elements in soil samples [5].…”

Neutron Activation Technique: A Reliable Tool to Determine the Mineral Composition in Agro-Industrial Products

“…Due to these constraints, the use of other methodologies for direct analysis of solid samples represents an advantage. Among them, there are X-ray fluorescence spectrometry (XRF) and neutron activation technique [12][13][14][15][16][17][18][19][20]. They are multielemental analysis that can be directly carried out on solid samples [21].…”

“…In this study, the technique of neutron activation analysis was applied, k0-standardized method [13][14][15][16][17][18][19][20]22] to several agro-industrial products to show its reliability to determine several elements in diversified matrices. In order to complete the study, one soil sample was also analysed, once it was intrinsically linked to agro products.…”