Collaborative Research: Coupled genetic, geochemical, and physical controls on arsenic mobilization

砷对人类健康造成的危害是众所周知的，没有比南亚/东南亚更好的例子了，在那里，砷污染的地下水的消费导致皮肤病和各种癌症的高发病率。 砷通常与沉积物中的氧化铁和其他矿物质结合在一起。 然而，在没有氧气的情况下，微生物可以进行铁和砷的还原反应，导致砷从沉积物中释放并在地下水中积累。 然而，铁与砷酸盐还原对砷释放的贡献尚不清楚。 此外，我们对砷的命运和土壤和沉积物中的运输的理解是有限的，不了解复杂的地下水流动途径内发生的生物和地球化学过程。 因此，本研究的首要目标是确定微生物代谢如何影响沉积物和土壤中砷的迁移。 具体来说，研究人员将调查细菌基因的表达负责铁和砷的减少和相称的生物地球化学过程负责控制砷的分区和流动性（沿着与他们的空间分布）在模拟自然土壤和沉积物的物理复杂性的模型系统。 拟议的研究整合了生物地球化学和分子遗传学的方法，旨在发展一个机制的理解微生物对地下水砷污染的影响。 由于砷问题的本质是植根于地球微生物学，拟议的研究的智力价值是产生重要的信息，了解机制（S）导致砷释放或沉积物中的保留。 结果将导致遗传学和地球化学过程如何影响微生物-矿物相互作用和砷命运的详细概念模型。该研究的更广泛的影响将是通过参加一个实验室研究导师计划（称为ACCESS），为代表性不足的群体的社区大学生和一个高中科学暑期项目，称为COSMOS，将研究与教学活动和社区推广相结合。 最后，这项合作将通过对斯坦福大学和UCSC的少数民族研究生进行校际指导来加强和促进多样性。

The hazards imposed by arsenic on human health are well recognized and nowhere better exemplified than South/Southeast Asia where the consumption of arsenic contaminated ground water has resulted high incidences of skin disorders and various cancers. Arsenic is usually associated with iron oxide and other minerals in sediments. However, in the absence of oxygen, microbes can carry out iron and arsenic reduction reactions that result in arsenic release from sediments and accumulation in ground water. The contribution of iron vs. arsenate reduction to arsenic release, however, is unclear. Furthermore, our understanding of arsenic fate and transport within soils and sediments is limited by poorly understood biological and geochemical processes occurring within complex ground water flow pathways. Therefore, the overarching goal of this research is to determine how microbial metabolism impacts arsenic transport in sediments and soils. Specifically, researchers will investigate the expression of bacterial genes responsible for iron and arsenic reduction and commensurate biogeochemical processes responsible for controlling the partitioning and mobility of arsenic (along with their spatial distribution) within model systems that simulate the physical complexity of natural soils and sediments. The proposed research integrates biogeochemical and molecular genetic approaches aimed at developing a mechanistic understanding of the impacts of microbes on arsenic contamination of ground water. Because the nature of the arsenic problem is rooted in geomicrobiology, the intellectual merit of the proposed research is the generation of crucial information important to understanding the mechanism(s) leading to arsenic release or retention in sediments. The results will lead to a detailed conceptual model of how genetics and geochemical processes impact microbe-mineral interactions and arsenic fate. The broader impacts of the research will be to integrate research with teaching activities and community outreach by participating in a laboratory research mentorship program (called ACCESS) for community college students of under represented groups and a high school science summer program called COSMOS. Lastly, the collaboration will enhance and promote diversity through intercampus mentorship of minority graduate students at both Stanford and UCSC.