updates

March 2019

We continue to build up our map of the levels of radioactive cesium along the west coast of North America (Figure 1). With the help of citizen scientists around the Pacific as well as through efforts on oceanographic research cruises we have found little change in 2018 over prior years, with some exceptions in coastal sites with a few samples being more elevated, and the trend still increasing in general (see Figure 2). Thanks to our citizen scientists and supporters, we hope to continue monitoring in the Pacific to understand the full consequences of the unprecedented releases and observe the return to pre-2011 conditions.

Figure 1. Levels of cesium-137 in water samples taken near the surface ocean between 2011 and 2018. All samples shown contain some pre-Fukushima cesium-137 due to nuclear weapons testing which in the region shown, is less than 2.0 Becquerels per cubic meter (Bq/m3 - light blue circles). Other colors indicate evidence of Fukushima-derived cesium at varying levels (Yellow = 2.0-3.9 Bq/m3; Orange = 4.0-7.9 Bq/m3; Brown = >8.0 Bq/m3).

Figure 2. Time history of cesium-137 vs. time, combining all coastal stations. The trend in general is for increasing cesium at all sites through 2018. The higher values in 2015 in Ucluelet BC, and a few elevated samples found in Bodega Head and San Luis Obispo in late 2017/early 2018, are transient events, most likely related to mixing of off shore waters, which are higher in cesium (see Figure 1) with coastal waters.

It is important to know that prior to 2011, there was already cesium-137 in the ocean remaining from atmospheric nuclear weapons testing that peaked in the 1960’s. Today, levels above 2.0 Becquerels per cubic meter (Bq/m3) in the surface ocean, indicate additional cesium from the Japanese releases. As noted last year, what we find along the west coast, while definitely showing an increase in cesium from the 2011 accident, the levels are still well below regulatory limits of 7,400 Bq/m3 set for drinking water (U.S. EPA). By our calculations, even if levels increase to 10 Bq/m3, swimming eight hours every day for an entire year, would only increase one’s annual dose by an amount, 1000 times less than a single dental X-ray.

Canadian researchers measuring cesium-137 in fish, are finding similarly low levels relative to regulatory thresholds in seafood, such as salmon. Taken together with ORO results, this provides important information about the transport of radioactive contaminants across the Pacific, along our coastlines, and through the food chain.

For a recent scientific publication linking the near shore and off shore cesium results in the context of oceanographic processes, see J. N. Smith et al., Environmental Science and Technology, 2017.

March 2018

Since March 2011, when a tsunami damaged the Fukushima Dai-ichi Nuclear Power Plant in Japan, we have documented the ongoing release of radioactive isotopes of cesium into the Pacific. We have focused on cesium is because it was one of the most abundant radioactive contaminants released, and some forms of it can remain in the environment for decades. Over the last seven years, with the help of citizen scientists around the Pacific as well as through research cruises and field expeditions, we have been able to track the spread of this element across the ocean and now along the western U,S, and Canadian coastlines. [ MORE ]

Figure 1. Levels of cesium-137 in water samples taken near the ocean surface between 2011 and 2017. All samples shown contain some pre-Fukushima detectable cesium-137 due to nuclear weapons testing (white circles) which in the region shown is less than 2.0 Bq/m3. Colored circles indicate evidence of Fukushima-derived cesium at varying levels, as indicated by color (Yellow = 2.0-3.9 Bq/m3; Orange = 4.0-7.9 Bq/m3; Brown = >8.0 Bq/m3). It is important to note that, prior to these events in 2011, there was already measurable amounts of radioactive fallout in the ocean left over from the testing of nuclear weapons that peaked in the 1960’s. For cesium-137, levels in Pacific Ocean surface waters were generally below 2.0 Becquerels per cubic meter (Bq/m3).1 We now see cesium-137 levels above this level at locations along coastlines in California, Oregon, Washington, British Colombia ,and Hawaii, as well as higher levels offshore (Figure 1). This increase, as well as our finding of cesium-134 in these elevated samples, provides clear evidence that Fukushima contamination has reached our shores. Figure 2. Updated cesium-137 versus sampling time at three U.S. coastal locations. The solid line indicates the linear trend over time and indicates increases at all four sites. Our most recent coastal sample collected in Bodega Bay, Calif., in 2017, showed 7.2 Bq/m3 of cesium-137, with other sites showing 4.8±0.1 Bq/m3 (Hawaii), 4.4±0.2 Bq/m3 (Mulkiteo, Wash.), and 6.4±0.2 Bq/m3 (Eureka, Calif.). In these site and elsewhere, the trend continues upward (Figure 2), with slightly higher levels found offshore. While elevated, these levels are still well below regulatory limits of 7,400 Bq/m3 set for drinking water (U.S. EPA). By our calculations, even if levels increase Bq/m3, swimming eight hours every day for an entire year would only increase one’s annual dose by an amount, 1000 times less than a single dental X-ray. Canadian researchers measuring cesium-137 in fish, are finding similarly low levels relative to regulatory thresholds in seafood, such as salmon. While low, this provides important information about the transport of radioactive contaminants across the Pacific, along our coastlines, and through the food chain. We hope to continue monitoring changes along the western North America coast to understand the full impact and to document the eventual return to pre-2011 conditions. Our thanks again, to all the citizens who, through their sampling efforts and financial support, have supported this important monitoring effort! 1One Bq = one disintegration per second; and one m3 is equivalent to about 264 gallons. [ LESS ]

March 2017

It has now been six years since the March 2011 tsunami off Japan damaged the Fukushima Dai-ichi Nuclear Power Plant and resulted in unprecedented releases of cesium-134, cesium-137, and many other gaseous and volatile radioactive elements to the Pacific Ocean. From the early days of the disaster, we have tracked the spread of these radioactive contaminants throughout the ocean and east towards North America. Since 2013, with the continuous support and sampling by citizen scientists with Our Radioactive Ocean (ORO), we have monitored the waters off the West and, in 2015 and 2016, samples collected by ORO volunteers showed the arrival and spread of contamination directly linked to Fukushima on this side of the Pacific. [ MORE ]

Figure 1. Cesium-137 vs. sampling time at 4 U.S. coastal locations. Dashed line is the linear trend showing small increases due to arrival of cesium from Fukushima. These levels are thousands of times lower than U.S, drinking water limits and lower than equivalent values in the ocean in the 1950s and 60s caused by nuclear weapons testing in the Pacific. Our work does not end with that discovery, however. TEPCO, the utility company that operated the plant and continues to oversee the cleanup effort, recently found the highest radiation levels to date (530 Sieverts) in Reactor 2, the one most heavily damaged by an explosion after the tsunami (see Washington Post article here). It is important to note that these measurements were the first to be made inside the primary containment vessel of Reactor 2, where radiation levels were expected to be high as a result of nuclear fuel being stored there. Although the long-term storage and removal of this material is of obvious concern, there is currently no evidence that this radiation is leaking from Reactor 2 into the surrounding air or water, but we continue to watch for signs that this might occur. For example, on our most recent cruise to Japan in November 2016 we found elevated cesium, but at levels no higher than what we saw in recent years. This means that the tons of water escaping the site remain contaminated, but at levels thousands of times lower than what we saw at the beginning of the accident. Given that the contamination has not lessened and still exists on-site, monitoring and remediation efforts need to continue throughout the decades-long decommissioning process to ensure that further releases do not occur. Until recently we have been using cesium-134 as a “fingerprint” of Fukushima in the Pacific. Because this isotope has only a two-year half-life and because we know of no other significant sources of it to the ocean, any amount we find must have come from Fukushima. After six years—three half-lives of the isotope—the amount of cesium-134 in the ocean has decayed to approximately 12% of the original amount released. This makes what was already in low concentration even more difficult to detect. Instead, we are now looking at the trend of increasing cesium-137 found along the West Coast as a more reliable signal indicating the presence of contamination from Fukushima. Our highest levels to date of cesium in coastal waters have been found near Pacific City, Oregon, with total cesium-137 levels between 2.8 and 3.2 Becquerels per cubic meter (Bq/m3) (Fig. 1a). Pre-Fukushima levels of cesium-137 along the coast were generally below 2 Bq/m3, mostly the result of nuclear weapons testing in the Pacific. Continuous monitoring at several sites (Point Reyes, Figure 1a; Pacific City, 1b; Bodega Head, 1c; and San Luis Obispo, 1d) has allowed us to identify a clear trend in the increase of cesium-137 over the past three years that also appears when we plot results from all coastal sampling sites. However, we do not have complete time series at many other sites, so we have compiled a map to indicate where we have seen the telltale sign of cesium-134 from Fukushima in prior sampling, both along the coast and further offshore (Figure 2). Figure 2. Map showing locations of samples with measurable cesium-134 (orange circles) carried by ocean currents from Fukushima. All samples have detectable cesium-137 as a result of atmospheric nuclear weapons testing in the 1950s and 60s. All data available at OurRadioactiveOcean.org (updated July 2016). It is important to note that the levels we see are still extremely low, more than 500 times below both the U.S. drinking water standard and any level thought to pose a harm to marine life or to humans as a result of swimming or other contact with sea water. We don’t expect these levels to get much higher, but until they start to decrease, we will not know what peak levels will be along West Coast beaches. Finally, we published an open-access review of Fukushima and its impact on the ocean (available here) in January 2017 that includes data from our sampling efforts to look at the spread of cesium across the Pacific to the West Coast. It also covers the changing levels of Fukushima contaminants in marine biota as well as the potential health effects and societal impacts of these releases. As we begin to see higher levels of cesium along the West Coast of North America and concerns continue to arise in the media and elsewhere, it becomes even more vital that we continue our monitoring efforts. We still need to determine the timing and magnitude of peak levels relative to releases from Fukushima, for example. It is also important that we continue provide the public with unbiased information about the impact of Fukushima on the ocean. We want to thank the hundreds of donors and citizen scientists who have made this possible and hope to continue our efforts into 2018 and beyond. [ LESS ]

December 3, 2015

Perhaps the biggest news of 2015 is that we have begun seeing more sites, especially offshore where we have expanded our sampling, with contamination directly linked to Fukushima. These data are important for two reasons: First, they indicate that, despite the presence of these radioactive isotopes, the levels of contamination remain well below government-established safety limits for human health or to marine life. Second, these long-lived radioisotopes will serve as markers for years to come for scientists studying ocean currents and mixing in coastal and offshore waters.

Before we get into the details of what we are finding, it's important to reiterate that almost any seawater sample from the Pacific will show traces of cesium-137, an isotope of cesium with a 30-year half-life, some of which is left over from nuclear weapons testing carried out in the 1950s to 1970s. The isotope cesium-134 is the "fingerprint" of Fukushima, but it decays much quicker (it has a 2-year half-life). When we find traces of cesium-134, we back-calculate from the amount we detected to determine how much was actually released from Fukushima in 2011. An equal amount of cesium-137 would have been released with it at the same time.[ MORE ]

Our highest detection level to date came from a sample collected about 1,600 miles west of San Francisco that contained 11 Becquerels per cubic meter of cesium-137 and cesium-134. This means that in one cubic meter of seawater (about 264 gallons), 11 radioactive decay events per second can be attributed to cesium atoms of both isotopes. That is 50 percent higher than we’ve seen before, but even these levels are still more than 500 times lower than safety limits established by the US government for drinking water and well below limits of concern for direct exposure while swimming, boating, or other recreational activities. Our findings agree with those reported by the scientists who are part of the group Kelp Watch and by the team of Canadian scientists working under the INFORM umbrella. We have presented data from Our Radioactive Ocean in public talks throughout the year, many of which are online, and this will continue with a talk at the San Francisco AGU meeting on December 14, the largest gathering of earth and space scientists in the world. Earlier this year, we produced a new brochure that takes a simple, accessible look at radiation and its impacts on the environment and on humans. You can download it here. We also continued to independently monitor the ongoing leaks from Fukushima Dai-ichi by sampling, as recently as this October, with our Japanese collaborators as close as one kilometer off the nuclear power plants. There is always more to do, and to this end we are working on several projects as we head to 2016. First, we are making some changes to the web site to improve usability. We’ve kept all data on the ORO results map (above), but now have a link just below it that takes you to a data visualization tool that gives visitors the ability to access and compare, data from Our Radioactive Ocean citizen scientists, as well as from earlier WHOI cruises off the coast of Japan, and we hope to add data gathered by our collaborators in Canada and Japan in the future. Second, we are moving ahead with development of the RadBand, a wearable device that gives any swimmer or surfer a chance to gather scientific data about the level of radioactive elements in the ocean just by going in the water. As results are shared and our user base grows, every person becomes a valuable data point as we expand the concept to other measurements of ocean properties. As we look back on 2015, we want to thank LUSH Cosmetics, Woods Hole Sea Grant, and the Pacific Blue Foundation who helped us expand our offshore sampling off California, and the more than 500 donors that have contributed to ORO in the past two years. With levels now increasing, there is more to do in 2016, and if there is anything our collective efforts underscore, it is the need to more closely monitor contamination levels across the Pacific. [ LESS ]

November 10, 2014: Fukushima Radioactivity Detected Off West Coast

Monitoring efforts along the Pacific Coast of the U.S. and Canada have detected the presence of small amounts of radioactivity from the 2011 Fukushima Dai-ichi Nuclear Power Plant accident 100 miles (150 km) due west of Eureka, California. Scientists at the Woods Hole Oceanographic Institution (WHOI) found the trace amounts of telltale radioactive compounds as part of their ongoing monitoring of natural and human sources of radioactivity in the ocean.

In the aftermath of the 2011 tsunami off Japan, the Fukushima Dai-ichi Nuclear Power Plant released cesium-134 and other radioactive elements into the ocean at unprecedented levels. Since then, the radioactive plume has traveled west across the Pacific, propelled largely by ocean currents and being diluted along the way. At their highest near the damaged nuclear power plant in 2011, radioactivity levels peaked at more than 10 million times the levels recently detected near North America.[ MORE ]