Collaborative Research: pH Dynamics and Interactive Effects of Multiple Processes in a River-Dominated Eutrophic Coastal Ocean

合作研究：以河流为主的富营养化沿岸海洋中多个过程的 pH 动态和相互作用效应

• 批准号: 1559279
• 负责人: Wei-Jun Cai
• 金额: $ 73.66万
• 依托单位: University of Delaware
• 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: 2016-05-15 至 2020-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1559279&HistoricalAwards=false
• 关键词: Collaborative; Research; pH; Dynamics; Interactive

Ocean acidification (OA) refers to the lowering of ocean pH (or increasing acidity) due to uptake of atmospheric carbon dioxide (CO2). A great deal of research has been done to understand how the open ocean is influenced by OA, but coastal systems have received little attention. In the northern Gulf of Mexico (nGOM) shelf region, pH in bottom waters can measure up to 0.45 units less than the pH of the pre-industrial surface ocean, in comparison to the 0.1 overall pH decrease across the entire ocean. Carbonate chemistry in the ocean is greatly influenced by even small changes in pH, so these seemingly minor changes lead to much greater impacts on the biology and chemistry of the ocean. The researchers plan to study coastal OA in the nGOM, a region subject to high inputs of nutrients from the Mississippi River. These inputs of anthropogenic nitrogen mostly derived from fertilizers leads to increased respiration rates which decreases oxygen concentrations in the water column to the point of hypoxia in the summer. This study will inform us how OA in coastal waters subject to eutrophication and hypoxia will impact the chemistry and biology of the region. The researchers are dedicated to outreach programs in the Gulf and east coast regions, interacting with K-12 students and teachers, undergraduate/graduate student training, and various outreach efforts (family workshops on OA, lectures for the public and federal, state, and local representatives). Also, a project website will be created to disseminate the research results to a wider audience. Increased uptakes of atmospheric carbon dioxide (CO2) by the ocean has led to a 0.1 unit decrease in seawater pH and carbonate mineral saturation state, a process known as Ocean Acidification (OA), which threatens the heath of marine organisms, alters marine ecosystems, and biogeochemical processes. Considerable attention has been focused on understanding the impact of OA on the open ocean but less attention has been given to coastal regions. Recent studies indicate that pH in bottom waters of the northern Gulf of Mexico (nGOM) shelf can be as much as 0.45 units lower relative to pre-industrial values. This occurs because the acidification resulting from increased CO2 inputs (both atmospheric inputs and in-situ respiration) decreases the buffering capacity of seawater. This interactive effect will increase with time, decreasing summertime nGOM bottom-water pH by an estimated 0.85 units and driving carbonate minerals to undersaturation by the end of this century. Researchers from the University of Delaware and the Louisiana Universities Marine Consortium will carry out a combined field, laboratory, and modeling program to address the following questions. (1) What are the physical, chemical, and biological controls on acidification in coastal waters impacted by the large, nutrient-laden Mississippi River?; (2) What is the link between coastal-water acidification, eutrophication, and hypoxia; (3) How do low pH and high CO2 concentrations in bottom waters affect CO2 out-gassing during fall and winter and storm periods when the water column is mixed?; and (4) What are the influences of changing river inputs under anthropogenic forcing on coastal water acidification? Results from this research aim to further our understanding of the processes influencing ocean acidification in coastal waters subject to eutrophication and hypoxia both in the GOM and river-dominated shelf ecosystems globally.

海洋酸化（OA）是指由于吸收大气二氧化碳（CO2）而导致海洋pH值（或增加酸度）。 已经进行了大量研究来了解开放海洋如何受到OA的影响，但是沿海系统几乎没有受到关注。 在整个海洋中的0.1总pH值相比，在墨西哥（NGOM）货架区域的北部地区，底部水中的pH值最多可以比工业前表面海洋的pH值少0.45个单位。海洋中的碳酸盐化学也受到pH值的微小变化的极大影响，因此这些看似较小的变化会导致对海洋生物学和化学的影响更大。研究人员计划在NGOM中研究沿海OA，该地区受到密西西比河的高度养分投入。 这些人为氮的输入主要来自肥料，导致呼吸速率增加，从而在夏季降低了水柱中的氧气浓度到缺氧。 这项研究将告知我们在沿海水域中的OA如何受到富营养化和缺氧的影响将如何影响该地区的化学和生物学。 研究人员致力于在海湾和东海岸地区的外展计划，与K-12学生和老师，本科/研究生培训以及各种外展工作（有关OA，公众和联邦，州和地方代表的讲座）的各种外展工作的互动）。 此外，将创建一个项目网站，以将研究结果传播给更广泛的受众。海洋对大气二氧化碳（CO2）的吸收增加，导致海水pH和碳酸盐矿物质饱和状态下降了0.1个单位，这一过程称为海洋酸化（OA），威胁着海洋生物体的荒地，改变了海洋生物生态系统和生物过程。非常关注的重点是理解OA对公海的影响，但对沿海地区的关注较少。 最近的研究表明，相对于工业前值，墨西哥北部（NGOM）货架底部的pH值可能低于0.45个单位。之所以发生这种情况，是因为二氧化碳输入增加（大气输入和原位呼吸）产生的酸化会降低海水的缓冲能力。 这种交互作用将随着时间的推移而增加，从估计的0.85个单位降低了夏季NGOM底部水pH，并在本世纪末驱动碳酸盐矿物质到饱和度。 特拉华大学和路易斯安那大学海洋联盟的研究人员将执行一个合并的领域，实验室和建模计划，以解决以下问题。 （1）受到大型，富含营养的密西西比河影响的沿海水域酸化的物理，化学和生物控制是什么？ （2）沿海 - 水酸化，富营养化和缺氧之间有什么联系； （3）当水柱混合时，底水中的低pH值和高二氧化碳浓度如何影响秋季和冬季和暴风雨期间的二氧化碳？ （4）在人为强迫下，变化的河流投入对沿海水酸化有什么影响？ 这项研究的结果旨在进一步理解影响沿海水域中海洋酸化的过程，但在全球GOM和以河流为主的货架生态系统中受到富营养化和缺氧的影响。