DISSERTATION RESEARCH: Effects of urbanization and climate change on denitrifier community structure and function

论文研究：城市化和气候变化对反硝化菌群落结构和功能的影响

• 批准号: 1011376
• 负责人: Justin Wright
• 金额: $ 1.29万
• 依托单位: Duke University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-09-01 至 2012-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1011376&HistoricalAwards=false
• 关键词: DISSERTATION; RESEARCH; Effects; urbanization; climate

Human welfare depends heavily on ecosystem services like water purification and nutrient cycling. Many of these natural services, in turn, rely on reactions performed by the most abundant and diverse group of organisms on Earth ? microbes. Remarkably little is known about how human drivers affect the structure and function of microbial communities. To help address this research gap, this project will involve a series of experiments to explore how urbanization and climate change may affect denitrifying bacteria (denitrifier) communities in streams. Denitrifiers are the only organisms that can permanently remove reactive nitrogen (N) from ecosystems. Too much reactive N in water bodies leads to serious water quality problems like harmful algal blooms and regional hypoxia. Denitrifiers in streams, therefore, provide an important ecosystem service. The project?s objective is to experimentally determine if and how multiple stressors commonly associated with watershed urbanization and climate change affect stream denitrifier community structure and function. These stressors include increased pollutant and nutrient concentrations, as well as higher temperatures. To meet this objective, microbial communities from eight different study streams will be subjected to combinations of chemical treatments (heavy metals, salt, and nutrients), and incubated at one of three temperatures (28, 38, and 48ºC). The amount of N removed will be measured over the incubation period and denitrifier community composition before and after incubation will be characterized by using molecular fingerprinting methods. Project results will be used to address whether 1) urbanization and climate change are likely to change denitrifier community structure, 2) changes to denitrifier community structure are likely to increase or decrease denitrification rates, and 3) interactions among stressors are additive or synergistic. Furthermore, by taking communities from study streams with various degrees of watershed urbanization, experiment results will be used to draw inferences on whether denitrifier communities and denitrification rates in urban versus forested streams are more or less sensitive to further environmental degradation. Most knowledge of streams comes from studying undisturbed streams, but the majority of U.S. streams are heavily impacted by human activity. Recently, there has been an explosion of research targeting N cycling in urban streams, but this work has largely ignored the microbial communities mediating N transformations. Findings from the proposed project will lead to new insights on denitrification, an important component of the N cycle, by exploring effects of urbanization and climate change on stream denitrifier communities. The project may provide information relevant to stream management and restoration efforts. Broader impacts will also include mentoring students. The doctoral student's dissertation research is being incorporated into the high school environmental science curriculum on human impacts on aquatic ecosystems being developed with a local high school teacher. Project findings will also be disseminated to the broader scientific community by written publications in peer reviewed journals and oral presentations at national conferences.

人类福祉在很大程度上取决于水净化和养分循环等生态系统服务。反过来，这些自然服务中的许多都依赖于地球上最丰富和最多样化的生物群所进行的反应。微生物关于人类司机如何影响微生物群落的结构和功能，人们知之甚少。为了帮助解决这一研究空白，该项目将涉及一系列实验，以探索城市化和气候变化如何影响溪流中的微生物群落。反硝化菌是唯一可以永久去除生态系统中活性氮（N）的生物。水体中过多的活性氮会导致严重的水质问题，如有害藻华和区域缺氧。因此，河流中的反硝化细菌提供了重要的生态系统服务。项目？的目的是通过实验来确定是否以及如何与流域城市化和气候变化的多重压力通常影响河流净化器社区的结构和功能。这些压力因素包括污染物和营养物浓度增加以及温度升高。为了实现这一目标，来自八个不同研究溪流的微生物群落将接受化学处理（重金属，盐和营养素）的组合，并在三种温度（28，38和48ºC）中的一种下培养。 将在培养期间测量去除的N的量，并且将通过使用分子指纹法来表征培养前后的堆肥群落组成。 项目结果将用于解决以下问题：1）城市化和气候变化是否可能改变硝化细菌群落结构; 2）硝化细菌群落结构的变化是否可能增加或减少反硝化速率; 3）压力源之间的相互作用是相加还是协同。此外，通过采取社区从研究流与不同程度的流域城市化，实验结果将被用来推断是否净化社区和反硝化速率在城市与森林溪流更敏感或更不敏感的进一步环境退化。 大多数关于溪流的知识来自于研究未受干扰的溪流，但美国的大多数溪流都受到人类活动的严重影响。最近，有一个爆炸性的研究针对N循环在城市河流，但这项工作在很大程度上忽略了微生物群落介导的N转换。该项目的研究结果将通过探索城市化和气候变化对溪流生物群落的影响，对氮循环的重要组成部分--反硝化作用产生新的认识。 该项目可提供与河流管理和恢复工作有关的信息。更广泛的影响还包括指导学生。博士生的论文研究正在被纳入高中环境科学课程人类对水生生态系统的影响正在与当地高中教师开发。项目研究结果还将通过在同行评审期刊上发表书面文章和在全国会议上口头陈述的方式向更广泛的科学界传播。