What will radiation do to sea life

Cesium, while much shorter-lived, will persist for a number of years. The chemical properties of radioactive cesium are similar to those of non-radioactive cesium and naturally occurring potassium and sodium, which are abundant in seawater. So all these end up in the same tissues, particularly muscle, of fish and other marine organisms.

But potassium and sodium are much less abundant in fresh water, so cesium uptake is much higher in freshwater organisms than in sea life. Fish also excrete cesium fairly efficiently, losing a few percent per day. So if fish are no longer exposed to new contamination sources, the levels in their tissue should decrease fairly quickly. Of particular concern for top-level consumers is the potential that these radioisotopes will be concentrated as they make their way up the food chain—what ecologists call biomagnification.

Fortunately, cesium shows only modest biomagnification in marine food chains—much less than mercury, a toxic metal, or many other harmful organic compounds such the insecticide DDT and polychlorinated biphenyls PCBs , Fisher said. On the cruise, he and his team measured cesium in everything they sampled.

As expected, concentrations were higher in organisms sampled closer to shore. Radioactive silver m Ag was also detected in all zooplankton samples. In all cases, however, the amounts of cesium and silver isotopes were much lower than those of naturally occurring potassium in the same samples.

Which is not, he noted, the same thing as saying that all marine organisms caught in the region are perfectly safe to eat. Jota Kanda, an oceanographer at the Tokyo University of Marine Science and Technology, has extensively studied coastal waters off Fukushima and calculated the amount of cesium still present in coastal waters shallower than meters feet and in sediments on the seafloor. By his reckoning, what remains is less than three percent of the total discharge, with the rest long since flushed out to the open ocean.

Yet levels of the cesium radioisotopes are still being measured at several tens to hundreds of becquerels per cubic meter in this area, Kanda noted, considerably higher than the levels prior to the Fukushima disaster. More importantly, levels measured in coastal sediments and in some species of fish are higher than those in the surrounding water.

As Kanda sees it, there are three sources responsible for this stubborn presence. One is river runoff—the fallout washed by rainfall into nearby rivers that drain to the sea. He also suggested that a small amount of contaminated water from basement compartments in the reaction unit housing is continuing to leak from the plant itself.

But the biggest culprit—the only plausible explanation for the steady levels of radioactive cesium being measured in fish tissue—is continuous input through a food source. And that, he said, points to sediments. Kanda has estimated that a total of 95 terabecquerels of cesium 10 12 becquerels is present in coastal sediments. The question, he maintained, is how it got there.

It could have drifted down to the seafloor in the fecal pellets of plankton that consumed it at the surface—and in fact, plankton in shallow waters sometimes showed elevated levels of cesium. It could also be arriving with organic bits and pieces carried along by river water. It could have adhered to clay particles that came in contact with contaminated water; such radioactive cesium is tightly bound to clay particles and may not be easily transferred to marine life.

Sediment is complex stuff, he explained. How contaminants are taken into these agglomerations is not well understood. Echoing Scott Fowler, Kanda noted that the composition and properties of sediments can vary dramatically. The key may be how long cesium stays put and the pathways for its uptake into the food chain. Given the year half-life of cesium, the sediments could be a possible source of contamination in the food chain for decades to come.

Fukushima and the Ocean. He uses techniques that span isotope geochemistry, next generation DNA sequencing, and satellite tagging to study the ecology of a wide variety of ocean species.

All forms of nuclear radiation travel in invisible rays, some rays are weak and would not pass through a piece of paper, but other rays can pass straight through metal. In the same way some rays can pass into our bodies, or be eaten or breathed in - but other rays are too big and cannot.

So, it is this invisible radiation which is causing worry, as it can spread miles and miles in the form of clouds, affecting other countries. Since low levels of radioactive waste have been discharged into the Irish Sea, the English Channel and the Arctic Ocean.

It is recognised that radioactive material needs to be isolated and encased in glass and concrete to prevent leakage on the ocean floor and it is now kept on land for some time whilst radioactivity levels decrease. What long term effects might this have on marine environments? Certainly radiation can enter the food chain though plankton and kelp and then go on to contaminate fish.

Radioactive caesium and plutonium has already been found in seals and porpoises in the Irish Sea. On 11th March the tragic earthquake and tsunami that hit Japan caused major damage to the Fukushima Daiichi nuclear power plant. This natural disaster caused thousands of tons of radioactive water to be released into the Pacific Ocean. But if the radiation leaks continue for several months, Japan may be dealing with a more serious blow to marine life, he said. All rights reserved. Radiation Can Cause "Bizarre Mutations" Once in seawater, radiation can hurt ocean animals in several ways—by killing them outright, creating "bizarre mutations" in their offspring, or passing radioactive material up the food chain, according to Joseph Rachlin , director of Lehman College's Laboratory for Marine and Estuarine Research in New York City.

Radiation Hardest on the Little Ones It's possible that levels of radioactive contamination near the Fukushima nuclear reactors could increase and cause some harm to local marine life, Whicker said. So "if they stop the source of radioactive leakage, this is going to be a short-term problem. Radiation Can Travel Up the Food Chain There could also be some movement of radiation up the food chain if animals eat irradiated plants and smaller, radioactive animals, Rachlin said.

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