Bachelor Thesis

Trace elements in white, red, black rice of the Camargue

Anica Schmalzl (12/2015-09/2016)

Support: Jörg Schaller, Britta Planer-Friedrich

French rice has a 1.5 to 3-fold higher amount of arsenic, compared to rice of Asian states. Whereby whole grain „brown“ rice and especially colored rice, commonly contain higher amounts of arsenic (480 μg/kg) than polished „white“ rice (200 μg/kg). The rice samples analyzed in this work originate from two red (RY203M, Tam Tam), one brown (Arelate) and one black (RZ200M) variety, grown at six different test field sites of the Centre Francais du Riz within the Camargue. The analysis of the total arsenic amounts, revealed that red rice had the highest arsenic concentrations. Especially the variety RY203M accumulates arsenic in the unpolished grains in high amounts (622 μg/kg). The brown (398 μg/kg) as well as the black (369 μg/kg) rice grains had lower concentrations of arsenic. The carcinogenic inorganic arsenite represents the dominant species (58-71 %) and was mostly accumulated within the bran. Whereas the organic species DMA mainly occured in the endosperm (25 %). A comparison between the amounts of inorganic arsenic and their As thresholds, set by the European Union, showed that all of the samples of the polished grain were below the limit of 200 μg/kg. However, nearly all of the unpolished grain exceed the limit of 250 μg/kg. Our results revealed that under the used conditions regarding soil chemistry, fertilization and water management of these six test fields, the plant-specific uptake mechanisms are determining to the amount of accumulated arsenic in rice grain. The amount of organic arsenic (particular DMA) accumulated in the rice grain was mainly influenced by the soil type.