US West Coast to be hard-hit by Fukushima radiation

Screenshot: IOP Science

An ocean current called the North Pacific Gyre is bringing Japanese radiation to the West Coast of the US. While many people assume that the ocean will dilute the Fukushima radiation, a previously-secret US government report revelas that the ocean may not adequately dilute radiation from nuclear accidents, and there could be “pockets” and “streams” of highly-concentrated radiation.

Scientists from the National Oceanic and Atmospheric Administration’s (NOAA) Pacific Marine Environmental Laboratory and 3 scientists from the GEOMAR Research Center for Marine Geosciences show that radiation on US West Coast could end up being 10 times higher than in Japan.

Screenshot: IOP Science

According to the study, after 10 years the concentrations become nearly homogeneous over the whole Pacific, with higher values in the east, extending along the North American coast with a maximum (~1 × 10−4) off Baja California.

Screenshot: IOP Science

With caution given to the various idealizations (unknown actual oceanic state during release, unknown release area, no biological effects included), the following conclusions may be drawn.

Dilution due to swift horizontal and vertical dispersion in the vicinity of the energetic Kuroshio regime leads to a rapid decrease of radioactivity levels during the first 2 years, with a decline of near-surface peak concentrations.

The magnitude of additional peak radioactivity should drop to values comparable to the pre-Fukushima levels after 6–9 years (i.e. total peak concentrations would then have declined below twice pre-Fukushima levels).

By then the tracer cloud will span almost the entire North Pacific, with peak concentrations off the North American coast an order-of-magnitude higher than in the western Pacific.

Screenshot: IOP Science

Indeed, another team of top Chinese scientists have just published a study in the Science China Earth Sciences journal showing that Fukushima nuclear pollution is becoming more concentrated as it approaches the West Coast of the United States, that the plume crosses the ocean in a nearly straight line toward North America, and that it appears to stay together with little dispersion.

The time scale of the nuclear pollutants reaching the west coast of America is 3.2 years if it is estimated using the surface drifting buoys and 3.9 years if it is estimated using the nuclear pollutant particulate tracers.

It is worth noting that due to the current near the shore cannot be well reconstructed by the global ocean reanalysis, some nuclear pollutant particulate tracers may come to rest in near shore area, which may result in additional uncertainty in the estimation of the impact strength.

Voice of Russia, IOP Science