CAREER: Microbial Reductive Dechlorination Coupled with Iron Corrosion

9984669 Chiu本研究旨在了解含氯溶剂地下水系统中厌氧微生物与单质铁的相互作用。元素铁和氢营养脱氯微生物培养的初步研究表明，两种地下水修复技术——渗透反应屏障（PRBs）和加速生物修复技术具有重要意义。虽然铁PRBs中复杂的生物地球化学过程会严重影响其长期性能，导致过早失效，但数据还表明，铁可能选择性地支持微生物脱氯，同时抑制竞争微生物，因此可用于提高厌氧生物修复的效率。将使用多佛混合培养及其非产甲烷亚种进行批量和长期柱实验，以研究(1)微生物定殖和脱氯对铁PRBs中氯化乙烯命运的影响；(2)利用铁加强生物脱氯以进行场地修复的潜力。将在不同深度连续采集头部空间和水样，以监测氯化乙烯及其子产物，氢，醋酸盐，甲烷和pH值。铁和水样品从批和柱实验也将检查共聚焦和电子显微镜和变性梯度凝胶电泳表征表面定植和微生物群落结构。此外，将从实地的PRBs取得铁和地下水的样本，并进行同样的检查。教育计划的重点是在本科课程中应用基于问题的学习，通过使用现实问题和鼓励以学生为中心的学习和团队合作来提高学习效果。有学术准备的学生，特别是那些来自代表性不足群体的学生，将被招募到这个和未来的研究项目中。通过开发以发现为基础的教学模块，将研究经验复制到课堂上，以便所有学生都能分享这些经验。基于问题的学习、本科研究和基于研究的教育将帮助学生培养批判性思维、解决问题的能力、团队合作能力和沟通能力。＊＊＊

9984669 Chiu This research is designed to understand the interactions between anaerobic microorganisms and elemental iron in groundwater systems containing chlorinated solvents. Preliminary work with elemental iron and a hydrogenotrophic, dechlorinating microbial culture suggests important implications for two groundwater remediation technologies, permeable reactive barriers (PRBs) and accelerated bioremediation. While complex biogeochemical processes in iron PRBs can critically affect their long term performance, leading to premature failure, data also suggest that iron may selectively support microbial dechlorination while suppressing competing microorganisms and thus may be used to enhance the efficiency of anaerobic bioremediation. Batch and long-term column experiments will be conducted using a Dover mixed culture and its non-methanogenic sub-culture to study (1) the effects of microbial colonization and dechlorination on the fate of chlorinated ethenes in iron PRBs and (2) the potential of using iron to enhance biological dechlorination for site remediation. Head space and aqueous samples will be taken continually at different depths to monitor chlorinated ethenes and their daughter products, hydrogen, acetate, methane and pH over time. Iron and aqueous samples from batch and column experiments will also be examined by confocal and electron microscopes and denaturing gradient gel electrophoresis to characterize surface colonization and microbial community structures. In addition, samples of iron and groundwater will be obtained from PRBs in the field and similarly examined. The education plan focuses on the application of problem-based learning in undergraduate courses to enhance learning effectiveness through the use of realistic problems and by encouraging student-centered learning and teamwork. Academically prepared students, especially those from underrepresented groups, will be recruited in this and future research projects. Research experience will be replicated in the classroom by developing discovery-based teaching modules so that the experience can be shared by all students. Problem-based learning, undergraduate research and research-based education will help students develop critical thinking, problem-solving, teamwork and communication skills. ***