Fukushima which isotopes

On the West Coast of North America, radiation from the water, sediment, and biota is even less of a problem because of the distance from Japan and the dilution that occurs as the contaminants cross the Pacific.

The greatest concern is for those who work on the site of the reactors because leaks from storage tanks could release water with high concentrations of contaminants.

How does Our Radioactive Ocean measure radiation in seawater samples? We use a method that is capable of detecting extremely low levels of the specific radioactivity produced by cesium isotopes released from Fukushima in seawater. First we pass a seawater sample through a column of cesium-absorbing beads made of a resin that has been optimized for use with seawater. Then we dry the resin and place it in a high-purity germanium well detector made by Canberra Industries for between 24 and 72 hours.

Every time a cesium atom decays, that event is registered in the instrument's detector, which has the ability to discern energy given off by two critical isotopes of cesium: cesium and cesium By counting the decay events associated with each isotope, we can calculate the total counts per second cps for a given sample. Knowing the efficiency of our detectors and something about the decay properties of the isotopes allows us to calculate the concentration of both cesium isotopes in a sample.

We regularly participate in proficiency tests with the International Atomic Energy Agency IAEA to ensure that our results are not just precise, but extremely accurate when compared to international seawater standards.

I have a Geiger counter. Can I use it to detect radiation from Fukushima? There are two basic types of radiation detectors—those that measure only the number of times radiation interacts with the instrument, and those that measure the energy level in electron volts of the particles or waves detected by the instrument. The Geiger-Mueller tube Geiger counter is perhaps the most widely known radiation detector and falls into the first category. Geiger counters can measure beta particles and gamma rays the detector window will block most alpha particles , but cannot distinguish between the two.

These interactions, and the decay events that trigger them, are registered as counts or audible clicks. In general, a Geiger counter will always produce some clicks, often 20 to 40 per minute, as a result of natural sources of radioactivity around us at all times, including rocks, soil, buildings and cosmic particles.

These background count rates vary widely depending upon local geology, altitude higher at higher elevations , and even construction materials and building design the accumulation of radon in basements is just one example. Detecting contamination from Japan above this background with a Geiger counter is only possible near the reactors and storage tanks at Fukushima, or in some of the more contaminated regions in Japan, as they are not particularly sensitive instruments.

In addition, Geiger counters cannot measure the energy level of the radiation being emitted, a very important factor in determining whether the source of radiation is manmade or natural. For example, the high count rates detected by a Geiger counter along a beach near San Francisco were not caused by cesium from Fukushima as originally reported, but rather caused by naturally occurring thorium-bearing minerals that are common and often elevated in some beach sands.

Are there other ways to detect Fukushima radiation in the ocean? In addition to measuring bulk seawater samples, as we do, other labs have analyzed radiation in fish and kelp. The studies provide much-needed information that seawater samples do not, but also present some issues of their own. Analyzing fish and other seafood, for example, tells us how much radiation a person or other marine animal might be exposed to by eating the contaminated organism, but it does not tell us how far the plume has spread from Fukushima or the concentration of the various radionuclides in the water where the organism was exposed.

Studies of kelp provide integrated time averaged, qualitative measure of kelp exposure to a wide range of radionuclides in the ocean, but do not give a precise indication of the exact level of the radionuclides at a given point in time in the ocean, as levels in kelp will vary not just with water concentration changes during the kelp growth cycle, but also variables such as ocean currents, and kelp physiology.

As a result, direct collection and analysis of radionuclides in water samples is the best way to determine how much contamination is in the ocean that poses an exposure risk to people and marine life. Are there different types of radiation? In general, there are two types of radiation, ionizing and non-ionizing. Non-ionizing radiation includes visible light and radio waves—things that, as the name implies, do not have the ability to form charged ions in other materials.

Ionizing radiation, however, does form charged ions and as a result presents a serious health threat because it can alter the atomic structure of living tissue. Ionizing radiation also comes in several different types, including alpha, beta, and gamma radiation, all with different degrees of concern and health impacts. What is the normal background level of radiation? The normal background level of radiation is different for different places on the planet.

In the ocean, the largest source of radiation comes from naturally occurring substances such as potassium and uranium, which are found at levels 1, to 10, times higher than any sources of radiation caused by humans. The largest human release of radionuclides was the result of atmospheric nuclear weapons tests carried out by the U. Despite even the high concentration of nuclear fallout in the Pacific caused by U.

What is the state of fisheries off Japan and along U. West Coast? Most Japanese fisheries were unaffected by Fukushima, but coastal fisheries nearest the reactors remain closed because of concern over exposure by some species, particularly those that live on or near the seafloor. These are being tested on a regular basis against Japan's limits for radiation in seafood which are much more strict than U.

There is currently no concern about the levels of cesium and other radionuclides in fish off the West Coast of the U. Are fish such as tuna that might have been exposed to radiation from Fukushima safe to eat? Seawater everywhere contains many naturally occurring radionuclides, the most common being polonium As a result, fish caught in the Pacific and elsewhere already have measurable, but small, quantities of these substances. Most fish do not migrate far from their spawning grounds, which is why some fisheries off Fukushima remain closed.

But some species, such as the Pacific bluefin tuna, swim long distances and could pick up cesium in their feeding grounds off Japan before crossing the Pacific.

However, cesium is a salt like potassium, and it will begin to flush out of exposed fish soon after they enter waters with lower contamination from Fukushima. By the time tuna are caught in the eastern Pacific, cesium levels in their flesh are times lower than when they were off Fukushima.

A study published in in the Proceedings of the National Academy of Sciences PNAS reported finding very low levels of cesium in Pacific bluefin tuna caught by recreational fisherman off the coast of California in August The FDA reviewed this study and determined that the levels of cesium were roughly times lower than levels that would prompt FDA to investigate further to determine if there were a health concern. Is there concern about other radionuclides, such as strontium? The continued release of radionuclides from groundwater and leaking tanks at Fukushima nuclear power plants site needs to be watched closely, as the character or mix of radionuclides is changing.

One example is the higher levels of strontium contained in groundwater and in storage tanks that are leaking into the ocean. Because strontium mimics calcium in humans and animals, it is taken up by and concentrated in bones, where it remains for long periods of time it has a half-life of 29 years and it is is not replaced as quickly in the body as cesium.

What we see is that the levels of cesium in the ocean are decreasing faster than strontium near the Fukushima nuclear power plant site. However, levels of both are much lower than at their peak in We remain most concerned about the potential of new releases from the thousands of storage tanks on the site, which contain highly radioactive water awaiting processing. Abstract On 11 March , a 9. Gov't Research Support, U. Gov't, P. Fukushima nuclear isotopes found in Californian wine Specialists at the University of Bordeaux have detected a spike in the radioactive caesium in vintage Napa Valley wines.

Fill 2 Copy 11 Created with Sketch. Friday 20 July , UK. Two radioactive cesium isotopes, cesium and cesium, have been detected offshore of Vancouver, British Columbia, researchers said at a news conference.

The detected concentrations are much lower than the Canadian safety limit for cesium levels in drinking water, said John Smith, a research scientist at Canada's Bedford Institute of Oceanography in Dartmouth, Nova Scotia. Tests conducted at U. Isotopes are atoms of the same element that have different numbers of neutrons in their nuclei.

In this case, cesium has more neutrons than cesium The scientists are tracking a radioactive plume from Japan's Fukushima Daiichi nuclear power plant.

Three nuclear reactors at the power plant melted down after the March 11, , Tohoku earthquake. The meltdown was triggered by the massive tsunami that followed the quake. The initial nuclear accident from the Fukushima reactors released several radioactive isotopes, such as iodine, cesium and cesium Cesium has a half-life of 30 years and remains in the environment for decades.

Cesium, with a half-life of only two years, is an unequivocal marker of Fukushima ocean contamination, Smith said. Cesium, on the other hand, is also present from nuclear weapons tests and discharge from nuclear power plants. Smith and his colleagues tracked rising levels of cesium at several ocean monitoring stations west of Vancouver in the North Pacific beginning in