COLLABORATIVE RESEARCH: Evaluating Calcification on a Hawaiian Coral Reef Using a Novel, Solid-State Total Alkalinity and pH Sensor

不断变化的环境条件，包括海洋变暖和海洋酸化，正在对海洋的化学成分和海洋生态系统，特别是珊瑚礁产生深远的影响。净生态系统钙化率(NEC)是珊瑚礁系统压力的有力指标，但缺乏能够在适当的时间和空间尺度上进行自主测量的传感器，限制了科学界全面检查推动珊瑚礁环境NEC变化的因素的能力。该项目通过进一步开发一种新技术来解决传感器的局限性，该技术可以每60秒测量总碱度和pH值。固态传感器的设计不依赖于需要更换或污染环境的化学试剂。这种新型传感器的实用性将在夏威夷的卡内奥赫湾得到证明，那里是世界上仪器最齐全、研究最充分的珊瑚礁生态系统之一。该项目的成功完成不仅将提高我们对NEC变化的驱动因素的了解，还将为社区提供一种新的海洋酸化传感器组件，可用于在各种情况下表征海洋碳系统。关于如何制造这些传感器的改进和文档将使社区离拥有商业上可行的系统更近一步，该系统可以过渡到工业中。这项工作将有助于向夏威夷管理人员以及拥有大量珊瑚礁结构的其他太平洋岛屿的管理人员介绍如何评估其珊瑚礁系统的健康和增长情况。该项目还将通过一名博士后助理和研究生的支持，帮助培训下一代海洋科学家，他们将学习将传感器应用于野外测量和海洋碳研究。固态、无试剂传感器组件基于ISFET库仑扩散滴定。研究人员建议建立四个系统来测试关键的钙化假说，这些假说最能用这些新传感器来解决。他们将在夏威夷卡内奥赫湾内的一个系泊设备上部署一个固定传感器，该设备靠近一个正在生长的珊瑚礁，并在卡内奥赫湾外的一个系泊设备上部署一个固定传感器，该设备主要代表进入珊瑚礁系统的水域。另外两个传感器包将安装在一个低调的水面漂浮器上，用于在系泊之间的礁石平台上进行拉格朗日研究。这些传感器将以前所未有的分辨率和精确度提供海水碳化学测量。同时描述进入珊瑚礁和离开珊瑚礁的水域将使调查人员能够在从分钟到季节的广泛时间尺度上研究珊瑚礁钙化的驱动因素。这一裁决反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Changing environmental conditions, including ocean warming and ocean acidification, are having a profound impact on the chemistry of the ocean and on marine ecosystems, particularly coral reefs. Net Ecosystem Calcification (NEC) rate is a strong indicator of stress in coral reef systems, but the lack of sensors that can make autonomous measurements at appropriate time and space scales has limited the scientific community's ability to fully examine the factors that drive NEC changes in coral reef environments. This project addresses the sensor limitation by furthering the development of a novel technology that can measure both total alkalinity and pH every 60 seconds. The solid-state sensor design does not rely on chemical reagents that need to be replaced or pollute the environment. The utility of this novel sensor will be proven in Kaneohe Bay Hawaii, one of the most well instrumented and studied coral reef ecosystems in the world. The successful completion of this project will not only improve our understanding of the drivers of NEC variability, but will also provide the community with a new ocean acidification sensor package that could be used to characterize the ocean carbon system under a wide variety of circumstances. The improvements and documentation produced on how to build these sensors will take the community one step closer to having a commercially viable system that could be transitioned to industry. This work will help inform Hawaiian managers as well as those from other Pacific Islands with substantial coral reef structures on how to evaluate the health and growth of their reef systems. This project will also help train the next generation of ocean scientists through support of a postdoctoral associate and graduate student who will learn to apply the sensor to field measurements and ocean carbon research. The solid-state, reagentless sensor package is based on an ISFET coulometric diffusion titration. The investigators propose to build four systems to test key calcification hypotheses that can best be addressed with these new sensors. They will deploy one stationary sensor on a mooring inside Kaneohe Bay Hawaii, in close proximity to an actively growing coral reef, and one stationary sensor on a mooring outside of Kaneohe Bay that is largely representative of the waters entering the reef system. Two additional sensor packages will be mounted in a low profile surface drifter for Lagrangian studies over the reef flat between the moorings. These sensors will provide measurements of seawater carbon chemistry at a resolution and precision not previously possible. The simultaneous characterization of waters entering the reef and leaving the reef will allow the investigators to study the drivers of reef calcification over a wide range of time-scales from minutes to seasons.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.