NSFOCE-BSF: Collaborative Research: The Role and Mechanisms of Nuclei-induced Calcium Carbonate Precipitation in the Coastal Carbon Cycle: A First In-depth Study

海水中碳酸钙（CaCO3）的形成是海洋碳循环的基本途径。碳酸钙的形成可以通过生物生产（生物体构建外壳或骨骼材料的钙化）或通过非生物（非生物或化学）过程发生。虽然大多数开放和沿海沃茨的表层海水碳酸钙过饱和，但有几个因素抑制了碳酸钙的非生物生产。因此，目前的范例是海水中大多数碳酸钙的形成是生物的。然而，实验室实验表明，向过饱和海水中添加固相颗粒可以通过提供沉淀“种子”来促进核诱导CaCO 3沉淀（NICP）。NICP已被证明在小巴哈马银行期间的事件重新悬浮的碳酸钙丰富的沉积物。直到最近，基本上没有证据表明NICP发生在典型的海洋系统中，其中悬浮颗粒的CaCO3含量相对较低。该项目的以色列合作伙伴最近的一项研究提供了证据，表明NICP可能在红海的碳预算中发挥重要作用，这是由于山洪暴发和潜在的空气尘埃造成的颗粒物质流入。这一发现表明，NICP可能是一个重要的CaCO3形成途径，在海洋碳循环中大多被忽视。该项目的目标是进行第一次全面深入的研究，以评估NICP在海洋中的意义。 该项目是美国和以色列科学家之间的国际合作，由NSF和美国共同资助。以色列两国科学基金会。一个博士后研究员，他的博士学位。这项研究的基础工作将通过该项目得到支持。一名以色列硕士生和一名美国少数民族大学生实习生将在该项目中接受咨询和培训。该项目将使用综合方法评估可能导致NICP的不同机制，包括河流沉积物输入，通过山洪暴发的陆源颗粒流入，底部沉积物再悬浮和大气尘埃输入。将在一系列沿海环境中进行实地调查：北方红海、密西西比河和萨宾河羽流以及北方墨西哥湾的加尔维斯顿湾，每个区域都有大量非碳酸盐丰富的沉积物。调查人员还将进行受控实验室实验，以核实和扩大实地观察。如果NICP被证明是重要的，这一发现可能会促进重新审查碳循环的重要部分和海洋碳系统对持续扰动的反应。

The formation of calcium carbonate (CaCO3) in seawater is a fundamental pathway in the marine carbon cycle. Calcium carbonate formation may occur through biological production (calcification by organisms building shells or skeletal material) or through non-biological (abiotic, or chemical) processes. Although most surface seawater in both open and coastal waters is supersaturated in calcium carbonate, several factors inhibit the abiotic production of calcium carbonate. Therefore the current paradigm is that most calcium carbonate formation in seawater is biological. However, laboratory experiments have demonstrated that addition of solid-phase particles to supersaturated seawater promotes nuclei-induced CaCO3 precipitation (NICP) by providing "seeds" for precipitation. NICP has been demonstrated in the Little Bahama Banks during events of re-suspension of CaCO3-rich sediments. Until very recently, essentially no evidence has shown that NICP occurs in typical marine systems where suspended particles have relatively low CaCO3 content. A recent study by the Israeli partners in this project provides evidence that NICP may play a significant role in the carbon budget in the Red Sea, as a result of an influx of particulate material caused by flash floods and potentially airborne dusts. Such a finding suggests that NICP may be an important CaCO3 formation pathway that has been mostly ignored in the ocean carbon cycle. The goal of this project is to conduct the first comprehensive, in-depth study to evaluate the significance of NICP in the oceans. The project is an international collaboration between U.S. and Israeli scientists, jointly funded by NSF and the U.S.-Israel Binational Science Foundation. A postdoctoral researcher whose Ph.D. work forms the foundation for this study will be supported through this project. An Israeli masters-level student and one U.S. minority undergraduate intern will be advised and trained in this project.The project will use an integrated approach to assess different mechanisms that may result in NICP, including riverine sediment input, land-derived particle influx via flash floods, bottom sediment resuspension, and atmospheric dust input. Field investigations will be done in a suite of coastal environments: the northern Red Sea, the Mississippi and Sabine River plumes and Galveston Bay in the northern Gulf of Mexico, each of which receive significant quantities of non-carbonate rich sediments. The investigators will also conduct controlled laboratory experiments to verify and extend field observations. If NICP is shown to be significant, this finding could promote a reexamination of important parts of the carbon cycle and the response of the ocean carbon system to ongoing perturbations.