Ocean Acidification: Influence of Ocean Acidification on Biotic Controls of DMS Emissions

到目前为止，对下个世纪预测的二氧化碳增加和海洋pH下降(海洋酸化)的生物地球化学后果的调查主要集中在碳的产生和去向上。关于海洋酸将如何影响其他生物地球化学循环或海洋与大气之间的活性痕量气体交换，人们所知的要少得多。痕量气体交换的变化将改变大气化学，包括气溶胶的形成和生长，并可能对气候变化产生反馈。在这个项目中，毕格罗海洋科学实验室的一个研究小组将研究海洋酸化对控制表层海洋中二甲基硫化物(DMS)浓度从而排放的生物过程的影响。该团队将在三个天然水中围体实验中研究OA对DMS循环的影响，这些实验旨在包含自然界对预测的不同程度的二氧化碳变化的反应。作为德国资助的BIOACID计划的一部分，他们将利用机会参与在亚热带海洋水域进行的一项重大实验，该实验涉及部署9个大范围(~60立方米)自由漂浮的远洋中温带。利用毕格罗新的中微体设施进行的两个重复实验将进一步扩大DMS-OA研究的环境范围。通过结合标准分析方法、最近开发的尖端示踪方法来确定加工速度，以及参与生物硫循环的潜在生物多样性和微生物的遗传反应，他们将确定改变的pH如何影响控制DMS浓度的关键生物路径和实验期间负责的微生物。更广泛的影响：所产生的信息将被用来为正在开发的全球海洋-大气耦合模式提供信息，从而能够审查海洋酸化对气候变化的影响。这些信息还将用于进一步发展以生理学为基础的生物地球化学生态系统模型的机械方法。一名博士后研究科学家将接受实验方法方面的培训，将通过与欧洲科学家合作获得建模经验，并将开展国际和美国合作，以期增加我们对海洋酸化对生态系统功能的理解。四名本科生、两名实习生和两名REU学生将通过参加毕格罗实验获得宝贵的经验。另一名具有数学背景的本科生将指导和参与解释和建模方面的工作。作为所有PI都将参与的Bigelow计划的一部分，将广泛推广到K-12学生和教师以及普通公众(Bloom，Cafe Science fique)。与科尔比学院(改变海洋学期)和岛屿学院的联合计划将分别惠及本科生和缅因岛K-8学校。

To date, investigations into the biogeochemical consequences of predicted increases in pCO2 and reduced pH in the oceans (ocean acidification, OA) over the next century have largely focused on the production and fate of carbon. Considerably less is known about how OA will influence other biogeochemical cycles or the exchange of reactive trace gases between ocean and atmosphere. Variations in trace gas exchange will alter atmospheric chemistry, including aerosol formation and growth, and potentially feedback on climate change. In this project, a research team at the Bigelow Laboratory for Ocean Sciences will study the influence of OA on the biological processes that govern the concentrations and hence emission, of dimethyl sulfide (DMS) in the surface oceans. The team will study OA effects on the DMS-cycle in three natural-water mesocosm experiments designed to encompass natural community responses to predicted changes in pCO2 of varying degrees. They will exploit the opportunity to participate in a major experiment in sub-tropical oceanic waters involving the deployment of nine large scale (~60 m3) free floating, pelagic mesocosms, as part of the German-funded BIOACID Program. Two replicate experiments conducted using the new mesocosm facilities at Bigelow will further expand the environmental range of DMS-OA studies. Through a combination of standard analytical approaches, recently developed cutting-edge tracer approaches to determine process rates, as well as the underlying organism diversity and genetic response of microbes involved with biogenic sulfur cycling, they will determine how altered pH influences key biological pathways governing DMS concentrations and the organisms responsible during the experiments. Broader Impacts: The information generated will be used to inform on-going development of global ocean-atmosphere coupled models, able to examine the influence of ocean acidification on climate change. The information will also be used to further develop physiology-based mechanistic approaches to biogeochemical ecosystem models. A Postdoctoral Research Scientist will be trained in the experimental approaches, will gain modeling experience by working with European scientists, and will develop international and US collaborations, with a common aim to increase our understanding of ocean acidification on ecosystem function. Four undergraduates, two interns and two REU-students, will gain valuable experience by participating in the Bigelow experiments. An additional undergraduate with a mathematical background will be mentored in and participate in the interpretation and modeling aspects. Extensive outreach to K-12 students and teachers as well as the general public will be pursued as part of established Bigelow programs in which all PIs will participate (BLOOM, Cafe Scientifique). Joint programs with Colby College (Changing Oceans semester) and Island Institute will reach undergraduates and Maine island K-8 schools, respectively.