Speciation and distribution of arsenic and localization of nutrients in rice grains.
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 (micro-XANES, micro-X-ray fluorescence (micro-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.
Lombi
E
E
Department of Agriculture and Ecology, Faculty of Life Science, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark.|Present address: Centre for Environmental Risk Assessment and Remediation, University of South Australia, Building X, Mawson Lakes Campus Mawson Lakes, South Australia, SA-5095 Australia and CRC CARE, PO Box 486, Salisbury, South Australia 5106, Australia.
Scheckel
K G
KG
National Risk Management Research Laboratory, US Environmental Protection Agency, 5995 Centre Hill Avenue, Cincinnati, Ohio 45224, USA.
Pallon
J
J
Division of Nuclear Physics, Department of Physics, Lund Institute of Technology, Lund University, PO Box 118, SE-221, Sweden.
Carey
A M
AM
Institute of Biological and Environmental Sciences, University of Aberdeen, Cruickshank Boulevard, St Machar Drive, Aberdeen, AB24 3UU, UK.
Zhu
Y G
YG
Research Centre for Eco-environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
Meharg
A A
AA
Institute of Biological and Environmental Sciences, University of Aberdeen, Cruickshank Boulevard, St Machar Drive, Aberdeen, AB24 3UU, UK.
D001151:Arsenic / Q000378:metabolism*; D001692:Biological Transport; D002851:Chromatography, High Pressure Liquid; D005453:Fluorescence; D008903:Minerals / Q000378:metabolism*; D012275:Oryza / Q000378:metabolism*; D011208:Powders; D012015:Reference Standards; D012639:Seeds / Q000378:metabolism*; D013054:Spectrophotometry, Atomic; D013057:Spectrum Analysis; D014965:X-Rays
D008903:Minerals; D011208:Powders; D001151:Arsenic