Table of Contents

• Dataset Description
  • Methods & Sampling
  • Data Processing Description
• Data Files
• Parameters
• Instruments
• Deployments
• Project Information
• Funding

Sediment trap flux data from two traps, at 500 m and 1000 m depth, deployed at the F1 mooring site offshore from the Fukushima Nuclear Power Plant (FNPP), 2011-2012.

Note (06 May 2014): Additional data from this sediment trap will be made available upon completion of futher analyses and manuscript publication.

Time-series sampling (from 19-July-2011 to 08-May-2012; refer to data for sampling interval) was undertaken using a standard McLane PARFLUX Mk8 sediment trap. All data were generated in the WHOI PARFLUX laboratory following standard procedures (Eggiman et al., 1980; Honjo et al., 1995). Samples were processed through a 10-positon sample splitter and aliquots dried and weighed to obtain mass flux data. Further samples were then digested using standard methods to obtain concentrations per known mass of sample.

Sample concentrations (mass/mass) have been multiplied by mass flux results (mass/area/time) to obtain fluxes of different chemical species. Thus concentration of parameter X, is multiplied by mass flux (F-mass) to obtain flux of parameter X (F-X): F-X = F-mass x [X]. 

There is one area where processing has led to questionable derived results because [Ca] values were used, instead of direct analysis, to calculate % inorganic C contents. The offending cells are highlighted in red in the original Excel file at cell AN10 and cell AX10.

Description from NSF award abstract:
The 2011 Tohoku earthquake off Japan resulted in a tsunami that severely damaged the Fukushima Dai-ichi nuclear power facility. Emergency cooling using seawater, in response to overheating of the facility's reactor units 1, 2 and 3 and uncontained spent fuel pools, has led to run-off of contaminated waters to the adjacent Pacific Ocean that, cumulatively, measure > 10,000 higher than pre-tsunami levels and exceed the release of radionuclides to the marine environment from Chernobyl accident.

With funding through this Grant for Rapid Response Research (RAPID), a research team at the Woods Hole Oceanographic Institution (WHOI) will participate in a JAMSTEC-led cruise in June-July 2011, and deploy a time-series sediment trap mooring at a station 80km off the coast of Japan. The specific goal will be to collect settling particulate radionuclide matter over the coming weeks and months through to an already-scheduled cruise to recover the moorings in May, 2012. By deploying traps at 500m and 1000m, the team will intercept particle-attached radionuclide settling out of the upper ocean and assess their fluxes into the deep ocean interior. They will collect fresh samples approximately every 2 weeks at each depth throughout the sampling period to complement "snap-shot" sampling that will be conducted aboard the JAMSTEC cruise at the start and end of the deployment period.

The team will also collaborate closely with Dr. Ken Buessler at WHOI (already funded separately, including a complementary NSF-RAPID project) who will be responsible for radionuclide analyses of particulate samples at no additional cost to this proposal. This project will handle preparation, deployment and recovery of the time-series sediment trap mooring as well as preliminary sample splitting, characterization of samples for biogeochemical properties and sample archiving. Radionuclides of primary interest at this time include 137Cs, 134Cs, 106Ru, 144Ce and 147Pm; other species (e.g. Pu isotopes) may also prove to be of interest within the lifetime of the deployment. Thus an important part of the project will also be to stand ready to provide further splits of these well characterized samples to US, Japanese and other interested international research groups in the future, as need arises.