Radioisotopes released into the atmosphere from the Dai-ichi nuclear power plant fell into the ocean.

Water used to cool reactors flushed radioisotopes into the sea.

Microscopic marine plants (phytoplankton) take up radioisotopes from seawater around them.

Contaminants move up the food chain from phytoplankton to tiny marine animals (zooplankton), fish larvae, fish, and larger predators. Different radioisotopes are taken up at different rates by different species.

Some contaminants end up in fecal pellets and other detrital particles that settle to the seafloor and accumulate in sediments.

Some radioisotopes in sediments may be remobilized into overlying waters and absorbed by bottom-dwelling organisms.

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