Investigating the Limits of Arsenic Methylation in the Critical Zone

Scott Maguffin博士已获得NSF博士后奖学金，在康奈尔大学和美国农业部的Dale Bumpers国家水稻研究中心开展研究和教育计划。本项目的目标是了解砷与临界区中有机化合物结合并限制其流动性的过程。Maguffin博士将使用地球化学和环境微生物学等方法相结合，研究砷污染的稻田土壤。这项研究将补充美国农业部戴尔邦珀斯中心正在进行的努力，以了解和减轻水稻对砷的吸收。深入了解土壤介导的砷-有机化合物相互作用的驱动因素将有助于全面了解土壤-植物-微生物相互作用如何调节水稻土中砷的生物有效性和毒性。这项研究的结果也将对生物挥发作为土壤和地下水补救工具的发展产生影响，因为几种形式的砷有机化合物物种是挥发性的。研究结果将通过在戴尔保险杠中心的联合研讨会分享。本科生将有机会参与研究，并将组织与水和食物中砷相关的外联活动，确保学生和社区对该项目和砷生物地球化学领域的高水平参与。砷甲基化是一种微生物解毒过程，其中微生物催化形成甲基化砷物种家族，显着改变毒性，流动性，和砷在临界区的命运。这项研究的工作假设是，微生物驱动的去甲基化与甲基化竞争，使砷返回无机形式，因此作为一个“神秘”的过程，抑制甲基化砷在环境中的积累。该调查将利用实验室实验，通过对微生物丰度和活动的分子生物标志物分析以及化学分析，确定不同生态系统微生物群落甲基化潜力的特征。新设计的“通用”arsM引物的功能基因分析将产生一个新的水平的知识的多样性，丰度和作为甲基化微生物在关键区环境中具有不同的地球化学性质的活动。

Dr. Scott Maguffin has been granted an NSF EAR Postdoctoral Fellowship to carry out research and education plans at Cornell University and the U.S. Department of Agriculture's Dale Bumpers National Rice Research Center. The goal of this project is to understand the process of arsenic bonding with organic compounds in the critical zone and limiting its mobility. Dr. Maguffin will use a combination of approaches, including geochemistry and environmental microbiology, to study arsenic-contaminated rice paddy soils. This research will complement ongoing efforts at the USDA Dale Bumpers Center to understand and mitigate arsenic uptake by rice plants. Insights into soil-mediated drivers of arsenic-organic compounds interactions will contribute to an integrated understanding of how soil-plant-microbe interactions regulate the bioavailability and toxicity of arsenic in rice paddy soils. Results from this study will also have implications for development of biovolatilization as a soil and groundwater remediation tool, since several forms of arsenic-organic compounds species are volatile. The research results will be shared through a joint seminar at the Dale Bumpers Center. Undergraduate students will have the opportunity to participate in the research, and outreach events related to arsenic in water and food will be organized, ensuring a high level of student and community engagement with this project and the field of arsenic biogeochemistry.Arsenic methylation, a microbial detoxification process in which microbes catalyze the formation of a family of methylated arsenic species, significantly changes the toxicity, mobility, and fate of arsenic in the critical zone. The working hypothesis for this study is that microbially-driven demethylation competes with methylation to return arsenic to inorganic forms, and thus acts as a "cryptic" process that suppresses the accumulation of methylated arsenic in the environment. The investigation will use laboratory experiments to characterize the methylation potential of microbial communities from the different ecosystems through molecular biomarker analyses of microbial abundance and activity, as well as through chemical analyses. Functional gene analyses with newly designed "universal" arsM primers will produce a new level of knowledge of the diversity, abundance, and activity of As-methylating microbes in critical zone environments with different geochemical properties.