You are here:
Speciation And Distribution Of Arsenic And Localization Of Nutrients In Rice Grains
Citation:
Lombi, E., K. G. SCHECKEL, J. Pallon, A. Carey, Y. G. Zhu, AND A. A. Meharg. Speciation And Distribution Of Arsenic And Localization Of Nutrients In Rice Grains. I. Woodward (ed.), NEW PHYTOLOGIST. Wiley InterScience, Silver Spring, MD, 184(1):193-201, (2009).
Impact/Purpose:
To overcome the limitations of the previous investigation by developing a technique that allowed preparation of thin sections (without embedding in resin), which increased the quality of the elemental mapping. To complement spatially resolved synchrotron analysis with 'bulk' XANES and particle induced X-ray emission (PIXE) analyses, which allows mapping of lighter elements (such as P, S and Si). And to investigate the localization of micronutrients, such as zinc (Zn) and iron (Fe) in the grains.
Description:
Arsenic (As) contamination of rice grains and the generally low concentration of micronutrients in rice have been recognized as a major concern for human health. Here, we investigated the speciation and localization of As and the distribution of (micro)nutrients in rice grains because these are key factors controlling bioavailability of nutrients and contaminants. Bulk total and speciation analyses using high-pressure liquid chromatography (HPLC)-inductively coupled plasma mass spectrometry (ICP-MS) and X-ray absorption near-edge spectroscopy (XANES) was complemented by spatially resolved microspectroscopic techniques (µ-XANES, µ-X-ray fluorescence (µ-XRF) and particle induced X-ray emission (PIXE)) to investigate both speciation and distribution of As and localization of nutrients in-situ. The distribution of As and micronutrients varied between the various parts of the grains (husk, bran and endosperm) and was characterized by element-specific distribution patterns. The speciation of As in bran and endosperm was dominated by As(III)-thiol complexes. The results indicate that the translocation from the maternal to filial tissues may be a bottleneck for As accumulation in the grain. Strong similarities between the distribution of iron (Fe), manganese (Mn) and phosphorus (P) and between zinc (Zn) and sulphur (S) may be indicative of complexation mechanisms in rice grains.
