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  • These nuclear weapon explosions were part of a series of 66 tests

  • by the United States government during the Cold War.

  • The tests were conducted on the Marshall Islands, a remote area of the Pacific Ocean

  • earmarked for unlimited nuclear destruction.

  • These are the islands today, which are mostly abandoned.

  • Though they look like any tropical paradise, these scenic views are tainted with radioactivity.

  • The radioactivity left behind is so high that you can't move back there,

  • you can't grow crops there, eat them; you can't drink the water.

  • So we're talking 70 years later, we can't go back to these sites.

  • But Ken Buesseler and his research team went back, to measure

  • just how contaminated this paradise is.

  • When a nuclear weapon explodes, hundreds of radioactive isotopes are released,

  • including plutonium-239, which has a half-life of 24,000 years.

  • And though that rate of decay may seem slow, if you're unfortunate enough to be exposed

  • to a large amount of this over a lifetime, it could lead to major health problems.

  • - It's called global fallout.

  • And the idea was, where did that end up, right?

  • And the oceans are one place where it ended up.

  • Is that in the water?

  • Did it sink to the bottom?

  • Is it in the marine biota?

  • So one of the goals of our research trip was to find where the highest levels were

  • of these radioactive contaminants: plutonium, cesium.

  • Places we looked were the craters left behind from the hydrogen bombs––that would be

  • the Mike Test on Enewetak, and Bravo Test on Bikini, 1954.

  • So these are tests that are thousands of times greater in magnitude and strength,

  • producing a thousand times more fallout locally and across the globe than the smaller tests.

  • A challenge that we had to this day is knowing that, if I find plutonium in the lagoon,

  • in an organism, is it from a particular test?

  • So we do a lot of what we call fingerprinting: it's a lot like forensics,

  • as you'd see in a crime scene.

  • Ken uses radioactive tracers like radium to determine where the plutonium has settled

  • and if it's leaking from wells, lagoons, or any other groundwater sites.

  • Ken and his team found that seafloor sediments contributed the most plutonium to the ocean.

  • This wasn't a complete surprise.

  • Until atmospheric nuclear testing was banned in 1963, more than 5 tons of plutonium

  • were dispersed in the atmosphere.

  • Most of this fell into the oceans and sank,

  • because plutonium is not readily soluble in seawater.

  • Cesium was only about two times higher.

  • Plutonium, within those islands, is about 100 times higher than just outside,

  • so there has to be a source, 70 years later.

  • Because of these nuclear tests so long ago, former inhabitants of these islands,

  • and now their younger generations, may never be able to live there again.

  • - This is definitely one of those nations that will suffer the most from sea level rise

  • due to climate change, so they have this double-whammy.

  • They have the radioactive waste that hasn't allowed them to move home, and now,

  • they're experiencing the effects of sea level rise and loss of their entire island,

  • all their atolls, a place to live.

  • Ken's research here on the Marshall Islands draw parallels to what can be learned

  • from the Fukushima disaster in 2011.

  • - One's a nuclear reactor accident, one was an intentional explosion of nuclear weapons, okay.

  • But still, for the people who live close to these accidents, these high sources,

  • there's always the question of, "when can I move back?"

  • "What does that mean in terms of my health and safety?"

  • It's been frustrating that we run 400+ reactors around the world's oceans

  • around the edges and inland, and yet we aren't maintaining a cadre of science

  • to deal with the environmental consequences of doing that.

  • We live in a radioactive world; we can't get away from it.

  • So, despite us knowing about levels, what's considered okay or not, for your exposure

  • through food and air, there's always something that maybe is not considered.

  • That makes it also very hard to say, when is it okay to move back to certain areas?

  • And that's the same for Japan, and it will be for Japan for years to come, as it is today,

  • 70 years later in the Marshall Islands.

  • For more episodes of Science in the Extremes, check out this one right here.

  • Don't forget to subscribe, and come back to Seeker for more episodes.

  • Thanks for watching!

These nuclear weapon explosions were part of a series of 66 tests

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Cold War Nuclear Fallout Is Still Affecting the Pacific, What Does That Mean for Us?

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    joey joey に公開 2021 年 04 月 16 日
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