EAGER: Perturbation of eukaryotic dynamics in a biostimulated groundwater aquifer

1007476 Mats虽然对污染对地上生态系统的影响(如水体富营养化)进行了很好的研究，但对污染对地下生态系统的影响知之甚少。这在一定程度上是因为地下水含水层中的真核群落生态学很少被研究，而且由于其在生物地球化学处理中的重要性而普遍得不到重视。总体而言，目前对真核生物的了解与工程活动对其活动、群落动态和正在进行生物修复的受污染地下水系统中的持久性的影响之间存在差距。PI一直在调查爱荷华州东南部被炸药RDX污染的含水层中的微生物群落结构，因为它正在接受醋酸盐的生物刺激，以此作为减少RDX的一种手段。他在这项提案中的目标是确定含水层生物刺激的具体后果，方法是在含水层中存在的真核生物群落中添加简单的碳。他的中心假设是，当被醋酸盐注射扰动时，被RDX污染的含水层中的真核生物动态将受到竞争排除和次级演替的生态学原则的支配，地方性真核生物将被世界性的通才真核生物所取代。为了验证中心假设，他提出了以下具体目标：(1)对含水层原始和碳修正部分的真核生物进行普查，以确定种群的质量差异。他的工作假设是，基于帕斯卡利斯研究和他自己的初步数据，含水层未受污染区域的真核生物组成将由甲壳类和其他专有地下水真核生物主导，而经乙酸盐修正的部分将由世界性原生动物和真菌等通才主导。(2)通过比较环境采样，确定真核生物因有机碳添加、扰动后的时间以及氧化还原状态的变化而发生的数量变化。他的工作假设基于生物扩散机制和次生演替理论，即在研究过程中(1年)，被过量有机碳和随后的厌氧条件取代的真核生物谱系将不会重新填充受影响的含水层部分。由于作为一门学科的工程学几乎完全考虑含水层中的原核生物，而没有解决对真核生物的补救行动的后果，拟议的活动可能导致在含水层生物学中创建关于修复活动的新范式，并在工程实践和对含水层中真核生物的当前理解之间架起一座桥梁。通过更好地了解含水层内生物过程和非生物因素之间的联系，可用来评估通过碳修正修复地下水是否会永久影响含水层生态系统结构，并对潜在后果进行假设。由于我们收集的数据将与生物修复管理活动期间收集的数据同时进行，拟议的研究还可能阐明真核生物是含水层状态和/或生物修复过程绩效的有用指标的可能性。拟议的活动为了解碳污染对含水层的影响提供了一个基础，因此对社会有潜在的好处。在该项目期间，将培训一名研究生和一名工科本科生，结果将在科学界和公众中传播。这项工作还将加强学术实体和行业合作伙伴之间的现有合作，并促进生物修复领域的研究、教育和实践。

1007476 MattesWhereas the effects of pollution on aboveground ecosystems are well studied (e.g. eutrophication of water bodies), comparatively little is known about the effects of pollution on subsurface ecosystems. This is partly because eukaryotic community ecology in groundwater aquifers is seldom studied and generally underappreciated for its importance in biogeochemical processing. In general, there currently exists a gap between what is known about eukaryotes and the consequences of engineering activities on their activity, community dynamics, and persistence in contaminated groundwater systems undergoing bioremediation. The PI has been investigating microbial community structure in an aquifer in southeastern Iowa contaminated with the explosive RDX as it is undergoing biostimulation with acetate as a means to effect RDX reduction. His objective in this proposal is to identify specific consequences of aquifer biostimulation by simple carbon addition to the eukaryotic communities present therein. His central hypothesis is that eukaryote dynamics in the RDX-contaminated aquifer, when perturbed by acetate injections, will be governed by the ecological principles of competitive exclusion and secondary succession with endemic eukaryotes being replaced by cosmopolitan generalist eukaryotes. To test the central hypothesis, he proposes the following specific aims: (1) perform a census of eukaryotes in pristine and carbon amended portions of the aquifer to identify qualitative differences in populations. His working hypothesis, based on PASCALIS studies and his own preliminary data, is that eukaryote composition in an unpolluted region of the aquifer will be dominated by crustaceans and other obligate groundwater eukaryotes while composition in a portion amended with acetate will be dominated by generalists such as cosmopolitan protists and fungi. (2) Ascertain quantitative changes of eukaryotes due to the addition of organic carbon, the time following perturbation, and the changes in redox state by comparative environmental sampling. His working hypothesis here, based on biological dispersal mechanics and secondary succession theory, is that eukaryotic lineages displaced by excessive organic carbon and subsequent anaerobic conditions will not re-populate affected aquifer portions during the course of the study (1 year).Because engineering as a discipline considers prokaryotes in aquifers almost exclusively without addressing the consequences of remedial actions to eukaryotic organisms, the proposed activities could lead to the creation of a new paradigm in aquifer biology with respect to remediation activities and a bridge between engineering practice and current understanding of eukaryotes in aquifers. A better understanding of the intra-aquifer linkages between biological processes and nonbiological factors could be used to evaluate whether or not groundwater remediation by carbon amendment will permanently affect aquifer ecosystem structure and to hypothesize potential consequences. Because the data we collect will be concurrent with data collected during bioremediation management activities, the proposed studies could also shed light on the possibility that eukaryotes are useful indicators of aquifer state and/or bioremediation process performance. The proposed activities represent a potential benefit to society by providing a basis for the understanding of effects in aquifers from carbon pollution. One graduate and one undergraduate engineering student will be trained during this project and results will be disseminated among the scientific community and the general public. This work will also strengthen the existing collaboration between an academic entity and an industry partner and serve to advance research, education, and practice in the bioremediation field.