Collaborative Research: Development of a Submersible, Autonomous Rn-222 Survey System

PI申请资金用于开发一种能够在远程操作车辆（ROV）或自主水下车辆（AUV）部署时进行现场222Rn分析的潜水系统。这样的系统将允许研究人员通过底部水的三维网格进行高分辨率氡测量，然后返回感兴趣的地点测量222Rn时间序列，以量化SGD通量。该系统的设计依赖于一种新技术，当氡被淹没时，通过在一个包含水柱的封闭空气循环中鼓泡，从水中喷射出氡进行分析。初步证据表明，这是一种可行的方法。海底地下水排放（SGD）作为一种向沿海海洋输送新养分和循环养分的重要机制正迅速得到认可。222Rn和镭同位素等化学示踪剂在探测地下水排放区和量化近岸（浅水）水域相关通量方面具有出色的实用性，但随着水柱加深、分层加强和物理混合变得更加复杂，对这些示踪剂进行采样和测量的传统方法逐渐变得不那么有用。在大陆架较深的水域(1)，露头的地质单元可以集中在SGD，以及(2)在珊瑚礁生态系统等关键栖息地周围，一个？美国测量这些示踪剂的能力仅限于获取采样尺度分辨率。这样的分辨率通常不足以理解这些排放的途径、驱动力和速率，也不利于量化相关的养分输送通量。因此，在评估SGD的全球意义之前，非常需要一种能够在大陆架较深水域原位连续测量SGD地球化学示踪剂的工具。更广泛的影响：由于本研究为其他科学家提供了一种新的研究工具，因此本研究的成功将对重要深盆地的SGD研究、量化热液流动的热液研究以及以Rn-222为示踪剂的深水循环和混合研究产生巨大而广泛的影响。调查人员还计划赞助一个为期两个学期的高级设计诊所团队，该团队由来自史密斯学院Picker工程项目的3-4名女本科生组成。这个本科团队将获得处理现实世界工程问题的经验，这个项目也将受益于他们的工程贡献。Breier与Smith学院就NDSF微生物垫采样器项目进行了类似的合作，双方的成果都很突出。Breier和Singh还将指导麻省理工学院/WHOI联合项目的博士生，作为该项目的一部分，希望史密斯学院的一名工程专业的学生可以完成这种过渡。彼得森还将担任本科生导师。

The PI's request funding to develop a submersible system capable of in situ 222Rn analysis while deployed from a remotely-operated vehicle (ROV) or autonomous underwater vehicle (AUV). Such a system would allow researchers to conduct high-resolution radon surveying through 3-D grids of bottom water and later return to sites of interest to measure a 222Rn time-series in order to quantify SGD fluxes. The system design relies on a new technique to sparge radon, while submerged, from the water for analysis via bubbling a closed air loop through a contained water column. Preliminary evidence shows this to be a viable approach. Submarine groundwater discharge (SGD) is quickly gaining recognition as an important delivery mechanism of new and recycled nutrients to the coastal ocean. Chemical tracers such as 222Rn and radium isotopes offer excellent utility at detecting groundwater discharge zones and quantifying associated fluxes in nearshore (shallow) waters, but the traditional approaches to sampling and measuring these tracers become progressively less useful as the water column deepens, stratification strengthens, and physical mixing becomes more complex. In deeper waters (1) of the continental shelf where outcropping geological units can focus SGD, and (2) around critical habitats like coral reef ecosystems, one?s ability to measure these tracers is limited to grab sampling-scale resolution. Such resolution is generally not sufficient to understand the pathways, driving forces, and rates of these discharges, nor is it conducive to quantifying associated nutrient delivery fluxes. Prior to assessing the global significance of SGD, then, there exists great need for a tool capable of in situ, continuous measurement of geochemical tracers of SGD in deeper waters of the continental shelf.Broader Impacts: Since this proposed study develops a new research tool available for other scientists, the success of this study will have a large and broad impact on SGD studies in important deep basins, hydrothermal studies quantifying hydrothermal flow, and deep-water circulation and mixing studies using Rn-222 as a tracer. The investigators have included a plan for outreach to sponsor a two-semester, senior Design Clinic team of 3-4 undergraduate female engineering students from Smith College's Picker Engineering Program. This undergraduate team will gain experience working on a real-world engineering problem and this project will likewise benefit from their engineering contribution. Breier has undertaken a similar collaboration with Smith College for the NDSF microbial mat sampler project and the results to both sides have been outstanding. Breier and Singh will also mentor a MIT/WHOI Joint Program Ph.D. student as part of this project, with the hope that one of the Smith College engineering students may make this transition. Peterson will also serve as an undergraduate mentor.