Correlation between nutrients, rare earth elements and heavy metals in O. Sativa rice plant organs by instrumentation neutron activation analysis and proton induced x-ray emission techniques

Abstract

The accumulation of halogens and metals from roots to stems, leaves and grains of Oryza sativa rice plant collected in Northern Senegal (St Louis region) at the same stages of growth but at different salinity soil levels was investigated by measuring their elemental concentration by invasive instrumental techniques of neutron activation analysis and proton induced x-ray emission. The normalized elemental concentration of Na, Cl, K, (Cs, Rb, Sr, Sb, Ba Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Cu, Zn, As, Se, Br, Rb, Sb was correlated with one of rare earth elements, La, Ce, Sm, Yb, Nd, Eu, Tb, Tm, and Lu) and the one of the heavy metals Hf, Ta and Th and to assess their subsequent distribution within the Oryza sativa rice plant in a particular salinity environment. The exploration of the experimental data was performed by applying machine learning techniques with Python to find their elemental correlations. This study shows that the accumulation of iron is highly correlated with the amount of rare earth elements and heavy metals investigated. We observe an inverse correlation between Fe and Cl concentrations in the roots and stems of the Oryza sativa rice plant, in which higher levels of Fe in the roots relative to stems correspond to lower levels of Cl. We also remark that there is no accumulation of rare earth elements in the root tissues of the different Oryza sativa rice plants studied. Whereas, in the stem, leaf, and grain organs there is a strong correlation between metal contents and rare earth elements.

Keywords:

• Elemental correlation
• INAA
• Oryza sativa
• PIXE
• robust statistics

Acknowledgments

The authors acknowledge the CANAM infrastructure and the Department of Physics from the Faculty of Sciences and Techniques of the Cheikh Anta Diop University for their support, P. Horáková and S. Fořtíková for their assistance with the sample preparation. We are very grateful to CEA AGRISAN for their valuable support in this study and for supporting the sampling campaign.

Disclosure statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Additional information

Funding

The research has been carried out at the CANAM (Center of Accelerators and Nuclear Analytical Methods) infrastructure (LM2015056) and has been supported by the project OP RDE financed by the Ministry of Education, Youth and Sports of the Czech Republic under the CANAM-OP Project No.CZ.02.1.01/0.0/0.0/16_013/0001812.