Tag Archives: Models

Misunderstanding Ocean Transport Models of the Fukushima Radionuclide Plume in the Pacific

by Jay T. Cullen

Introduction

This post is part of an ongoing series that endeavors to provide useful and accurate information about: 1) the fate of Fukushima derived radionuclides in the Pacific Ocean, and, 2) the impact of these radionuclides on the marine ecosystem and the west coast of North America. The purpose of this diary is to draw attention to a number of poorly researched posts about a recently published study (unfortunately this study is behind a publisher pay-wall) in a Chinese journal that predicts a concentrated plume of radioactive elements from Fukushima arriving on the west coast. It is an unfortunate but common example of how news aggregation sites can misinterpret the results of a scientific study and misinform the public.


What models can and cannot say about the Fukushima plume

The study in question by Fu and co-workers published in the Journal of Ocean University of China in 2014 (behind pay-wall unfortunately) is wholly incapable of describing the behavior of dissolved radionuclides in the plume that is now arriving on the west coast of North America.

From the paper the authors themselves state in the methods that:

“In the study, the radioactive pollutant in the ocean is treated as a mixture of multiple Lagrangian particulates, and each particulate represents a radioactive element. The particulates can move in both horizontal and vertical directions, but cannot diffuse and mix with surrounding seawater.”

What this means is that rather than being allowed to mix and diffuse (or decay or sink after becoming associated with particles) the radionuclides are treated as neutrally buoyant drifters. The model, therefore, greatly overestimates the concentrations of radionuclides reaching the west coast of North America in the plume.

For those interested in models using accurate physics that will allow for an accurate prediction of radionuclide concentrations consult the following studies:

Behrens et al. (2012) and Rossi et al. (2013) (behind pay-wall)

Snapshot of the high-resolution (0.1°) model field, taken at the end of the tracer injection period (end of April, model year 0): shading indicates the thickness of the surface mixed layer (in m); contouring illustrates the surface velocity field indicated by local stream lines.
Snapshot of the high-resolution (0.1°) model field, from Behrens et al. taken at the end of the tracer injection period (end of April, model year 0): shading indicates the thickness of the surface mixed layer (in m); contouring illustrates the surface velocity field indicated by local stream lines and clearly identifies the high velocity Kuroshio and Kuroshio extension.

The Behrens et al. study is open-access while the Rossi et al. study is not. Measurements taken in the North Pacific by Canada’s Department of Fisheries and Oceans and InFORM team member Dr. John Smith indicate that the Rossi et al. study predicts the arrival time of the plume on the west coast but overestimates the activity of the Fukushima derived radionuclide 137-Cs. Behrens et al. predict a too late time of arrival but with lower activities that appear to more realistic. It important to note that these models carry the own simplifications and assumptions (e.g. see section 3.4 Caveats of the Behrens et al. (2012) study) and that recent measurements suggest that some of the Fukushima plume is being dispersed to the south rather than to the east in the Pacific (e.g. Kumamoto et al. (2014) open-access; more on this study in a forthcoming post).

Articles that confuse the conclusions of the Chinese study are a good example of poor reporting on an important subject. The example here was originally spawned by Energy News who have a history of inaccurate reporting on Fukushima and then propagated through the web by uncritical followers of the site.

Advertisements

MEOPAR Announces Funding for New Ocean Fukushima Radioactivity Monitoring Project

University of Victoria Press Release

Integrated Fukushima Ocean Radionuclide Monitoring (InFORM) Network: A collaborative radiation monitoring network to determine and communicate environmental risks for Canada’s Pacific and Arctic Oceans from the Fukushima-Daiichi nuclear accident

A new marine radioactivity monitoring network that will engage scientists in Canada and the US, health experts, non-governmental organizations—and citizen scientists along the British Columbia coast.

The InFORM Network—which stands for Integrated Fukushima Ocean Radionuclide Monitoring—is being funded by $630,000 over three years by the Marine Environmental Observation Prediction and Response Network (MEOPAR).

Since the 2011 tsunami and Fukushima-Daiichi nuclear disaster in Japan, there’s been widespread concern along the coast of western North America about the potential danger posed by low-level radioactivity crossing the Pacific Ocean.

“There’s great public demand for information about the impact of the Fukushima disaster on the marine ecosystem and on the health of British Columbians,” says Cullen. “Our goal is to provide the public with the best information possible about risks to the environment and their health.”

Research partners in the network include: Woods Hole Oceanographic Institution in Massachusetts; Health Canada; the University of Ottawa; the University of British Columbia; and Fisheries and Oceans Canada (DFO).

Ocean circulation models disagree on the timing and concentrations of radioactive elements expected off BC. The radioactive plume of seawater arrived along our coast in June 2013, and levels detected so far don’t pose a health risk.

“In the next few years, as the highest concentrations from this plume arrive, we need to know what the concentrations are and what kind of risks they pose,” says Cullen. “And we won’t know that unless we monitor the situation properly.”

The network will involve NGOs such as the Clayoquot Biosphere Trust, the Georgia Strait Alliance, the Raincoast Education Society, the Living Oceans Society and the David Suzuki Foundation, which will help with public outreach, information transfer, and recruitment and training of citizen scientists.

The plan is to set up 10 to 15 community sites along the BC coast where volunteer citizen scientists will collect water and seafood samples monthly or bimonthly for analysis.

Those samples will supplement measurements already being taken offshore by DFO and an existing citizen scientist network coordinated by Woods Hole that extends from the Bering Strait to San Diego.

“End-user involvement is a key pillar of this network,” says Cullen. “By engaging directly with the public, we’re inviting those with a stake and interest in marine environmental risk assessment to get involved.”

Cullen says results will be disseminated online and through community town hall meetings up and down the coast. He’s currently setting up an InFORM website, and results will also be posted on the www.ourradioactiveocean.org/ website hosted by Woods Hole.

MEOPAR is a team of Canadian researchers in the natural and social sciences who are trying to better understand and predict the impact of marine hazards on human activities and ecosystems. It’s hosted by Dalhousie University in Nova Scotia and funded by the federal Networks of Centre of Excellence Program.

For more information on the InFORM network, visit www.FukushimaInform.ca and Facebook, follow @FukushimainFORM or contact Jay Cullen at jcullen@uvic.ca.