Transforming our understanding of DIC Photoproduction in Oceanic Waters

改变我们对 DIC 海洋水域摄影制作的理解

• 批准号: 1635618
• 负责人: Jay Brandes
• 金额: $ 52.71万
• 依托单位: University of Georgia Research Foundation Inc
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-01 至 2021-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1635618&HistoricalAwards=false
• 关键词: Transforming; our; understanding; DIC; Photoproduction

Photoproduction describes chemical reactions which use the energy of sunlight to change the molecular structure of one product to another. This process has been shown to play an important role in the coastal ocean changing dissolved organic carbon (DOC) to dissolved inorganic carbon (DIC); however, minimal information is available on the extent to which this process takes place in the open ocean. The main obstacle to obtaining DIC production data for open ocean waters is the inability to measure the small DIC production rates against the large background of seawater DIC. Currently the most common method for high precision measurement of DIC production has unacceptable detection limits to resolve this difference. Researchers from the University of Georgia have developed MoDIE (Moderate DI13C Isotope Enrichment), a novel means of determining low levels of DIC produced in the open ocean with high precision. As part of this project, they plan to refine their MoDIE method and obtain measurements of DIC photoproduction in open ocean waters (i.e, South Atlantic Bight, North Atlantic Ocean and North Pacific Ocean subtropical gyres). Results from this work will provide improved estimates of DIC photoproduction in the open ocean which in turn will improve existing models of carbon cycling. The broader impacts of this project are particularly exciting. The proponents plan to create an exhibit at the University of Georgia Marine Extension public aquarium to teach the general public about ocean color and marine carbon cycling. In addition, they plan to participate in the Skidaway Institute for Oceanography ?Marine Science Day? open house to share their science with the public and incorporate results into their class curricula. One of the researchers is a first-time investigator who plans to incorporate education and training of undergraduate and graduate students in the project. Finally, undergraduate interns from underrepresented groups will be involved in the project to give them research experience and help with retention in a science discipline and career.Photoproduction of dissolved inorganic carbon (DIC) from dissolved organic carbon (DOC) has been shown to be a non-negligible process in the marine carbon cycle; however, it is still unclear the extent and importance of this process to the overall carbon cycle in the open ocean (blue water chemistry). The major issue causing this uncertainty is the lack of available methods with acceptable detection limits. The high background of DIC in the open ocean (2mM) makes it difficult to measure the photoproduced portion of DIC when the detection limits are high. Additionally, the current best method requires pre-stripping samples of background DIC, which could introduce unnecessary errors by over manipulating samples. This project will develop a new method called MoDIE (Moderate DI13C Isotope Enrichment) to get accurate measurements of DIC photoproduction in the open ocean. MoDIE works by enriching a sample in 13C and monitoring the dilution of DI13C under irradiation using liquid chromatography-isotope ratio mass spectrometry (LC-IRMS). By removing the need for pre-sample treatment and introducing a highly precise measurement technique, the researchers will be able to compare their techniques with published methods of photochemical DIC detection and put forth more accurate estimate of marine DIC photoproduction in the global ocean. This will greatly improve marine carbon cycle models.

光生作用描述了利用太阳光的能量将一种产物的分子结构改变为另一种产物的化学反应。 这一过程已被证明在沿海海洋溶解有机碳（DOC）溶解无机碳（DIC）的变化中发挥了重要作用;然而，关于这一过程在公海中发生的程度的信息很少。 获得开放海洋沃茨DIC生产数据的主要障碍是无法测量海水DIC大背景下的小DIC生产率。目前，用于DIC生产的高精度测量的最常见方法具有不可接受的检测限来解决这种差异。 来自格鲁吉亚大学的研究人员开发了MoDIE（中等DI 13 C同位素富集），这是一种高精度测定公海中产生的低水平DIC的新方法。 作为该项目的一部分，他们计划改进MoDIE方法并获得公海沃茨水域（即南大西洋湾、北大西洋和北太平洋亚热带环流）中DIC光生产物的测量结果。 这项工作的结果将提供更好的估计DIC光合作用在开放的海洋，这反过来又将改善现有的碳循环模型。 该项目的广泛影响尤其令人兴奋。 支持者计划在格鲁吉亚大学海洋推广公共水族馆举办一个展览，向公众介绍海洋颜色和海洋碳循环。此外，他们还计划参加斯基达韦海洋学研究所？海洋科学日？开放的房子，与公众分享他们的科学，并将结果纳入他们的课堂课程。 其中一名研究人员是第一次调查，他计划将本科生和研究生的教育和培训纳入该项目。 最后，来自代表性不足群体的本科生实习生将参与该项目，为他们提供研究经验，并帮助他们留在科学学科和职业生涯中。溶解有机碳（DOC）的溶解无机碳（DIC）已被证明是海洋碳循环中不可忽视的过程;然而，这一过程对公海整个碳循环（蓝水化学）的程度和重要性仍不清楚。 造成这种不确定性的主要问题是缺乏具有可接受检测限的可用方法。开放海洋中DIC的高背景（2 mM）使得当检测限高时难以测量DIC的光生部分。另外，当前最佳方法需要背景DIC的预剥离样本，这可能通过过度操纵样本而引入不必要的误差。该项目将开发一种名为MoDIE（中等DI 13 C同位素富集）的新方法，以准确测量开放海洋中DIC的光生产物。MoDIE的工作原理是富集样品中的13 C，并使用液相色谱-同位素比质谱法（LC-IRMS）在辐照下监测DI 13 C的稀释度。通过消除对预样品处理的需要并引入高度精确的测量技术，研究人员将能够将他们的技术与已发表的光化学DIC检测方法进行比较，并对全球海洋中的海洋DIC光生作用进行更准确的估计。这将大大改善海洋碳循环模型。