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

PI要求提供资金，以开发一种能够在远程操作的车辆（ROV）或自主水下航行器（AUV）部署时进行现场222 Rn分析的潜水系统。这样的系统将使研究人员能够通过3D网格进行高分辨率的氡测量，然后返回到感兴趣的地点测量222 Rn时间序列，以量化SGD通量。该系统的设计依赖于一种新的技术，通过在封闭的空气回路中鼓泡通过所包含的水柱，从水中喷射氡进行分析。初步证据表明，这是一种可行的方法。海底地下水排放（SGD）作为向沿海海洋输送新的和回收的营养物质的重要机制，迅速得到人们的认可。222 Rn和镭同位素等化学示踪剂在探测地下水排泄区和量化近岸（浅水）沃茨中的相关通量方面具有很好的实用性，但随着水柱加深、分层加强和物理混合变得更加复杂，传统的取样和测量这些示踪剂的方法变得越来越不实用。在更深的沃茨（1）大陆架，其中露头地质单元可以集中SGD，（2）周围的关键栖息地，如珊瑚礁生态系统，一个？的能力，以衡量这些示踪剂是有限的，以抓住采样规模的分辨率。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的全球重要性之前，非常需要一种能够在大陆架较深沃茨现场连续测量SGD地球化学示踪物的工具。 由于这项拟议的研究为其他科学家开发了一种新的研究工具，这项研究的成功将对重要深盆地的SGD研究、量化热液流的热液研究以及使用Rn-222作为示踪剂的深水循环和混合研究产生巨大而广泛的影响。调查人员已经包括了一个推广计划，赞助一个两学期的高级设计诊所团队，由来自史密斯学院皮卡工程项目的3-4名本科女工程学生组成。这个本科团队将获得在现实世界的工程问题上工作的经验，这个项目也将受益于他们的工程贡献。Breier还与史密斯学院进行了类似的合作，用于NDSF微生物垫采样器项目，双方的结果都很出色。Breier和Singh还将指导麻省理工学院/WHOI联合项目博士。学生作为这个项目的一部分，希望史密斯学院的一个工程专业的学生可以实现这一转变。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.