Over Three years of Monitoring 129I spread in Pacific Ocean After the 2011 Fukushima Daiichi Nuclear Power Plant Accident

¹²⁹I is a long-lived radionuclide that has been used as a useful environmental tracer. At present, the global ¹²⁹I in surface water is about 1-2 orders of magnitude higher than pre-1990 levels. The anthropogenic ¹²⁹I signal produced from industrial nuclear fuel reprocessing plants is known to be the primary source of ¹²⁹I in marine surface waters of the Atlantic, and elevated ¹²⁹I values are found globally.

The Great East Japan Earthquake and the induced tsunami in 2011 triggered the nuclear shutdowns, failures, and partial meltdowns of Fukushima Daiichi Nuclear Power Plant. The accident resulted in a series of radioactive material releases into the environment and spread out through atmospheric and ocean circulation. We will present ¹²⁹I results of water samples collected weekly near Scripps Institution of Oceanography, San Diego, CA for the past 3 years. We also have several measurements collected a year apart from Kaohsiung, Taiwan, which represent west margin of Pacific Ocean, and from Alaska, Washington, and Oregon. By establishing ¹²⁹I time series, we can observe the spread of ¹²⁹I in the surface waters of the Pacific Ocean that resulted from the accidental releases.