Further refinements of a continuous radon monitor for surface ocean water measurements

Abstract

Radon is an excellent natural tracer for studying various geophysical processes. In the past centuries, radon isotopes measurement approaches for marine research have been fully developed but still suffer limitations. Here we present the setup and validation of an improved continuous online measurement system (PIC-ORn) to measure dissolved radon in the surface ocean and other water bodies. We demonstrated that the PIC measurement efficiency is ~2 times higher than a RAD7 and is less affected by relative humidity and produces reliable results. Laboratorial measurements indicated that the new PIC-ORn system responded timely to the change of radon activities in water. The new system was successfully deployed during a cruise to the northwest Pacific Ocean in June 2021. Despite low radon-in-water activities, the results obtained by the new PIC-ORn system matched the traditional measurement systems within the estimated uncertainties. The PIC-ORn detector takes advantage of higher efficiency, lower cost, and power consumption, and is less affected by air moisture. The new system does not rely on drying units, further reducing on-site supervision, which would benefit the researches in submarine groundwater advection and diffusion and ocean-atmosphere gas exchange.

Radon concentration and affecting environmental conditions in water-curtain heated cultivation facilities

“…The radon concentration data were calculated as the 10-min average of the decay events. One-hour averages of the values were used to smooth out the statistical scatter [ 15 ]. The OriginPro 8 software (OriginLab) was used to analyze the data.…”

A Review of Marine In Situ Sensors and Biosensors

“…In aquatic and marine environments, radon is valuable as a tracer of specific geophysical processes, such as measuring air/sea gas piston velocities and looking for groundwater flows into surface waters [80,81]. The half-of of radon-222 (3.83 day) is much longer than that of radon-219 (3.96 s) and radon-220 (55.6 s) [82], so radon-222 is suitable for being measured and used in studies, such as diffusion from sediments [83], earthquake studies [84], submarine groundwater discharges [9,14], land-sea interaction [85], springs [86], carbon dioxide capture and storage tasks [87], air-sea interaction [88], greenhouse gas emissions and climate change [89], energy resources (especially in the deep sea) [90].…”

“…Ltd., 2019. (c) Automated pulsed-ionization chamber Oceanic Rn monitor (PIC-ORn)-radon measurement system for tracking radon levels in water over timereproduced from [82] with permission from Frontiers Media SA., 2022. (d) In situ submersible radon (OUC-Rn) measurement system, reproduced from [8] with permission from Frontiers Media SA., 2022.…”

“…In addition, sensing systems based on a pulsed ionization chamber are also popular and attractive for detecting radon. Li et al reported an automated pulsed ionization chamber Oceanic Rn monitor (PIC-ORn) measurement system to measure dissolved radon in the surface ocean (Figure 3c) [82]. Compared to the commercial RAD-7 sensor, the system measuring efficiency is around two times higher and less impacted by relative humidity with lower cost and power consumption.…”