Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
• Related Publications
• Parameters
• Instruments
• Project Information
• Funding

These data were collected in order to optimize a new method for degassing dissolved radon-222 from water. This dataset includes the experimental (Bell) results. See also the control dataset (https://www.bco-dmo.org/dataset/826844). The general premise is the use of a sparging chamber (‘Bell’) that is deployed underwater and uses bubbles to degas the radon. 

See methodology outlined in Peterson et al., 2013 (Journal of Radioanalytical and Nuclear Chemistry). The sparging chamber is connected to a commercially-available radon-in-air monitor (RAD7; Durridge Co.) via a closed air loop.  Air exiting the RAD7 circulates to the bottom of the sparging chamber where it enters via aquarium bubblers.  The bubbles rise through the sparging chamber and accumulate in a headspace, from which air is pumped through desiccant back to the RAD7.  

Our control to which we compare the sparging chamber is the commercially-available RAD-Aqua (Durridge Co.) which sprays a water sample into a chamber rather than using bubbles.  Otherwise, the setups are similar.

Data contained herein are various laboratory testing configurations to optimize dimensions of the sparging chamber, number and type of bubblers, and any benefits from adding an additional sprayer capability to the top of the sparging chamber.  All configurations tested are accompanied by a number of replicates.

BCO-DMO Processing Notes:
- data submitted in 57 Excel files, Sheet name "Bell_2675" and an Excel file "Sample Summary.xlsx", sheet "Run Summary", and extracted to csv
- the 57 files were concatenated and joined with the summary file, adding columns: Date, Chamber, Bubblers, Sprayer_Status, Water_Source, Bell_RAD7_SN, Exchanger_RAD7_SN.
- added conventional header with dataset name, PI name, version date
- modified parameter names to conform with BCO-DMO naming conventions
- added 'ISO_DateTIme' column, re-formatted date from m/d/yyyy to yyyy-mm-dd
- in 'Chamber' column, replaced " with -inch
- replaced #DIV/0! with nd for /no data'
- formatted date-time column to ISO_DateTime (yyyy-mm-ddTHH:MM:SS)

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.