Research Starter Grant: Biogeochemical and grain-arsenic impacts of rice-residue incorporation into rice paddy soil

稻米受砷污染是一个全球性问题。由于砷是一种有毒物质，食用大米可能会对人类健康构成威胁。该项目旨在通过使用可溶性硅(Si)改良土壤来降低稻米中的砷含量，从而保护人类健康。由于水稻对亚砷酸盐和硅的共同吸收途径，溶解硅竞争植物吸收亚砷酸盐(稻田土壤溶液中的主要形态)，从而降低根吸收和籽粒砷水平。虽然土壤中的硅总量很高，但可溶(因此也就是植物可利用的)硅要低得多，特别是在种植大多数水稻和积累硅的植物(如水稻)从土壤中开采硅并被移除的较老的(更风化的)土壤中。高硅稻渣还田可降低砷的吸收/储粮，提高产量，从而保护人类健康。由于新鲜的植物材料可能会促进温室气体的产生，本项目将测试稻壳灰(高硅)对降低稻米对砷的吸收和浓度的效果。如果证明有效，这种管理做法可以在全世界范围内采用，包括发展中国家的小农户农场，只需最小的成本或改变目前的管理战略。该项目将允许购买封闭式微波消解装置，这将帮助首席研究员Seyfferth博士建立她的研究小组，并使她和她的小组能够在未来几年进行基础科学研究。最后，塞弗斯博士有一个让代表性不足的群体的成员参与科学研究的可靠记录，这将在整个项目和未来的项目中继续下去。

The contamination of rice grains by arsenic is a global problem. Since arsenic is a poison, rice consumption may pose a threat to human health. This project aims to decrease the arsenic concentration in rice grains and thus protect human health from rice consumption by amending soil with soluble silicon (Si). Increased dissolved silicon can decrease root-uptake and grain-levels of arsenic due to competition for plant-uptake of arsenite (the dominant form in rice paddy soil solution) by dissolved silicon because arsenite and silicon share an uptake pathway in rice. While the total amount of silicon in soils is high, the soluble (and thus plant-available) silicon is much lower, particularly in older (more weathered) soils where most rice is grown and where silicon accumulating plants (such as rice) mine silicon out of soil and are removed. Return of silicon to soil from rice residues with a high Si content may decrease arsenic uptake/grain storage, increase yields, and thus protect human health. Since fresh plant material may promote greenhouse gas production, this project will test the effect of rice husk ash (which is high in silicon) on decreasing arsenic uptake and concentration in rice grains. If proven effective, this management practice could be adopted worldwide, including small-holder farms in the developing world, with minimal cost or change to current management strategies. This project will allow for the purchase of a closed-vessel microwave digestion unit which will aid the Principal Investigator, Dr. Seyfferth, in establishing her research group and allowing her and her group to conduct basic science for years to come. Finally, Dr. Seyfferth has a proven record of involving members of underrepresented groups in science, which will continue throughout this project and in future projects.