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Agronomic Amendments for Mitigation of Organic Arsenic Uptake by Rice


<p>The long-term goal of this research is understand how As, particularly organic species, enter rice and to develop techniques for reducing the risk As presents to human health via exposure to contaminated rice. </p><p>To accomplish this goal, I have set the following objectives:</p><p><ol><li>Investigate the effect of Si amendments on organic As uptake in hydroponic rice. Hypothesis: Si amendments will have minimal effects on organic As uptake.</li><li> Test additional amendments for their ability to outcompete DMA and MMA uptake by hydroponic rice. Hypothesis: A compound with similar physicochemical properties to DMA and MMA will compete with the transport of these organic As compounds.</li><li> Assess the effect of ammonium addition on organic As uptake in hydroponic rice. Hypothesis: Ammonium addition will acidify the apoplastic space increasing uptake of MMA and DMA.</li><li> Perform field trials with amendments identified in objectives 1, 2, and 3. Hypothesis: Hydroponic experimental results will be representative of field trial results. </li></ol></p>

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Worldwide, arsenic frequently contaminates rice, presenting a risk to food safety. Additions of silicon have shown promise in reducing uptake of arsenite, but reducing uptake of organic arsenic is less studied. Uptake of organic arsenic compounds may also cause straight-head disease in rice, thereby lowering yields. The overall goal of this research is to develop agronomic techniques for reducing rice uptake of organic arsenic compounds, particularly monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA). Towards this goal, the project will investigate the following three factors' ability to limit rice uptake of organic arsenic: silicon amendments, organic acid amendments, and nitrogen source. Amendments successful in reducing uptake of DMA and MMA in hydroponic studies will be tested in field trials to improve the nation's food safety via reduced risk to consumers. This project also includes several career development and mentorship aspects, including the co-development of a plant-contaminant interactions course, mentorship of students, attending career development workshops, and learning of new analytical skills. My mentor, Dr. Seyfferth, will be an invaluable asset due to her experience with uptake of inorganic contaminants by agronomic crops. This project will aid my personal goal of becoming a leading teacher-scholar at an academic institution through the unique skills and experiences of my mentor and the facilities at the University of Delaware.

Limmer, Matt
University of Delaware
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