CoccolitHophore controls on ocean ALKalinitY (CHALKY)

CoccolitHophore 对海洋碱度（CHALKY）的控制

• 批准号: NE/Y004426/1
• 负责人: David McKee
• 金额: $ 51.4万
• 依托单位: University of Strathclyde
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FY004426%2F1
• 关键词: CoccolitHophore; controls; ocean; ALKalinitY; CHALKY

Each year in the North Atlantic Ocean, a key region for the global carbon cycle, immense areas of surface water turn turquoise in summer. This phenomenon relates to the growth and death of unique microscopic algae - coccolithophores. Coccolithophores cover their cells with scales of calcium carbonate (called coccoliths), produced internally and arranged into an exoskeleton around the cell. Under certain conditions, for example when nutrients are scarce or viruses infect cells, these coccoliths are shed in huge numbers. Due to their unique optical properties and immense abundance, they turn the water a milky turquoise colour and can be detected from space. These turquoise waters (termed 'white waters') are where coccoliths have accumulated in their trillions and have been considered as coccolithophore blooms.Coccolithophores form coccoliths through calcification, which produces CO2 and reduces the pH of the ocean by consuming alkalinity. When coccoliths are lost from the surface ocean, it reduces the capacity of the ocean to absorb more CO2. In this way, 'white waters' are thought to lead to significant reductions in the ocean's carbon sink. However, we now suspect that these 'white waters' are not areas of intensive coccolithophore calcification or growth, rather they are regions of senescence and an accumulation of detrital material. Coccolithophores have been found to grow faster and calcify more outside of the 'white waters' and more recently we have found that they are also heavily grazed by small animals (zooplankton) who partly digest the calcium carbonate. In this way, coccolithophore calcium carbonate appears to be recycled far more in surface waters than previously thought and the alkalinity they are associated with may be retained in the surface ocean. However, we have few coupled measurements of the balance of these different processes (growth, death and sinking) with which to take an informed view of how coccolithophores control ocean alkalinity. This represents a major uncertainty in the global marine C-cycle, with global C budgets and Earth System Models struggling to incorporate calcium carbonate or accurately replicate observations of seawater alkalinity. The 'coccolithophore controls on ocean alkalinity' (CHALKY) project aims to fill this critical knowledge gap by quantifying the balance of coccolithophore production and loss processes and their impact on C-cycling and air-sea CO2 fluxes. Our assessment of ecological interactions and impacts on seawater chemistry will be carried out while improving in situ and remotely sensed optical detection of coccolithophores to allow us to use Earth Observation data to scale our insights to the global ocean and historically using existing satellite data sets. CHALKY will, for the first time, concurrently quantify coccolithophore calcium carbonate production (consuming alkalinity), viral lysis (retaining alkalinity), zooplankton grazing (also retaining alkalinity) and sinking fluxes into the ocean's interior (removing alkalinity). We will look at the balance of these processes during the transition from late-spring to summer, when in situ and satellite data informs us that coccolithophores are most active. We combine a research cruise measuring these processes with autonomous platforms and state-of-the-art sensors measuring ocean chemistry and in situ optical properties. By quantifying the key growth and loss processes, within the context of seawater carbonate chemistry and C-cycling, CHALKY will inform a more accurate representation of how biology impacts the ability of seawater to absorb CO2, allowing closer matching of observations and models and inclusion of calcium carbonate in global C budgets.

每年在北大西洋，这是全球碳循环的关键区域，地表水在夏季变成绿松石。这种现象涉及独特的微观藻类 - 氯菊花的生长和死亡。碳酸盐量覆盖其细胞，并用碳酸钙（称为Coccoliths），内部产生并排列成细胞周围的外骨骼。在某些条件下，例如，当营养稀缺或感染细胞病毒时，这些可可人士的脱落大量。由于它们独特的光学特性和巨大的丰度，它们将水变成乳状绿松石色，可以从太空中检测到。这些绿松石的水（称为“白水”）是在数万亿美元积累的地方，被认为是钙化菌的Coccolithophore blooms.Cococolithophotors形成钙化，通过钙化产生CO2，从而产生CO2并通过消耗黄质量来减少pH。当Coccoliths从地面海洋中丢失时，它会降低海洋吸收更多二氧化碳的能力。这样，“白水”被认为会导致海洋水槽大幅减少。但是，我们现在怀疑这些“白水”不是密集的球谷钙化或生长的区域，而是它们是衰老的区域和碎屑物质的积累。已经发现，在“白水域”之外，发现球形岩的生长速度更快，并且最近发现它们也受到部分消化碳酸钙的小动物（浮游动物）的大量放牧。这样，碳酸钙似乎在地表水中被回收远远超过了以前的想象，并且与它们相关的碱度可以保留在地面海洋中。但是，我们几乎没有对这些不同过程（生长，死亡和沉没）平衡的耦合测量，可以了解到，对球虫如何控制海洋碱度。这代表了全球海洋c周期的主要不确定性，全球C预算和地球系统模型努力掺入碳酸钙或准确地复制海水碱度的观察结果。 “ Cococolithophore对海洋碱度的控制”（Chalky）项目旨在通过量化Coccolithophore生产和损失过程的平衡及其对C-C-Cycling和Air-Sea CO2磁通量的影响来填补这一关键的知识差距。我们将对生态相互作用以及对海水化学的影响进行评估，同时改善原位，并远程感知的可去核岩的光学检测，以使我们能够使用地球观测数据将我们的见解扩展到全球海洋，并使用现有的卫星数据集将其扩展到全球海洋，并在历史上扩展到历史上。白垩，首次将同时量化碳酸钙产量（消耗碱度），病毒裂解（保留碱度），浮游动物（也保留了碱度）（也保留了碱度）并沉入海洋内部（去除碱度）。在从春末到夏季的过渡期间，我们将研究这些过程的平衡，当时的原位和卫星数据告诉我们，球虫是最活跃的。我们将测量这些过程的研究巡航与自主平台和最先进的传感器进行了测量，可测量海洋化学和原位光学性能。通过在海水碳酸盐化学和C-Cycling的背景下量化关键的生长和损失过程，Chalky将更准确地表示生物学如何影响海水吸收CO2的能力，从而使观测值和模型更紧密地匹配，并在全球C预算中含有碳酸盐含量。