EAGER: Perturbation of eukaryotic dynamics in a biostimulated groundwater aquifer

1007476 mattes虽然污染对地上生态系统的影响（例如水体的富营养化）已经得到了很好的研究，但对污染对地下生态系统的影响却知之甚少。这部分是因为地下水含水层的真核生物群落生态学很少被研究，而且其在生物地球化学处理中的重要性通常被低估。总的来说，目前对真核生物的了解与工程活动对其活性、群落动态和在受污染地下水系统中进行生物修复的持久性的影响之间存在差距。在爱荷华州东南部的一个受爆炸性RDX污染的含水层中，PI正在对微生物群落结构进行调查，因为该含水层正在进行醋酸生物刺激，以达到减少RDX的目的。他在这一建议中的目标是通过简单的碳添加到存在于其中的真核生物群落中来确定含水层生物刺激的具体后果。他的中心假设是，在rdx污染的含水层中，当被醋酸酯注入干扰时，真核生物的动力学将受到竞争排斥和次生演替的生态原则的支配，地方性真核生物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。基于PASCALIS的研究和他自己的初步数据，他的工作假设是，在含水层未受污染的区域，真核生物的组成将以甲壳类动物和其他专门的地下水真核生物为主，而在含有乙酸盐的部分，真核生物的组成将以世界原生生物和真菌等多面体为主。(2)通过对比环境采样，确定真核生物因添加有机碳、扰动后的时间以及氧化还原态的变化所引起的定量变化。基于生物扩散力学和次生演替理论，他的工作假设是，在研究过程中（1年），被过量有机碳和随后的厌氧条件所取代的真核生物谱系不会重新填充受影响的含水层部分。由于工程作为一门学科几乎只考虑含水层中的原核生物，而不考虑对真核生物采取补救行动的后果，因此，拟议的活动可能导致在含水层生物学中建立一个关于补救活动的新范例，并在工程实践和当前对含水层真核生物的理解之间架起一座桥梁。更好地了解生物过程和非生物因素在含水层内的联系，可以用来评估通过碳修正的地下水修复是否会永久影响含水层生态系统结构，并假设潜在的后果。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，因此拟议的研究还可以阐明真核生物是含水层状态和/或生物修复过程性能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基础，对社会有潜在的好处。在这个项目中，将培训一名研究生和一名工科本科生，并将结果在科学界和公众中传播。这项工作还将加强学术实体与行业合作伙伴之间的现有合作，并有助于推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.