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。由于砷是一种毒药，食用大米可能对人体健康构成威胁。该项目旨在通过用可溶性硅（Si）改良土壤，降低稻米中的砷浓度，从而保护人类健康免受稻米消费的影响。由于亚砷酸盐和硅在水稻中共享一条吸收途径，因此溶解硅的增加会降低砷的根吸收和籽粒吸收水平，这是由于溶解硅与植物对亚砷酸盐（水稻土壤溶液中的主要形式）的吸收存在竞争。虽然土壤中硅的总量很高，但可溶性（因此植物可利用的）硅要低得多，特别是在种植水稻的较老（更风化的）土壤中，以及硅积累植物（如水稻）从土壤中开采硅并被移除的土壤中。硅含量高的水稻残体向土壤返回硅可以减少砷的吸收/粮食储存，提高产量，从而保护人类健康。由于新鲜植物材料可能促进温室气体的产生，本项目将测试稻壳灰（硅含量高）对降低稻谷中砷吸收和浓度的影响。如果证明有效，这种管理办法可以在世界范围内采用，包括发展中世界的小农场，成本最低或改变目前的管理战略。该项目将允许购买一个密闭容器微波消化装置，这将帮助首席研究员，Seyfferth博士，建立她的研究小组，并允许她和她的小组在未来几年进行基础科学研究。最后，Seyfferth博士在涉及科学界代表性不足的群体成员方面有着良好的记录，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.