Measurements of 129I in the Pacific Ocean at Scripps Pier and Pacific Northwest sites: A search for effects from the 2011 Fukushima Daiichi Nuclear Power Plant accident and Hanford

Ching-Chih Chang; George S Burr; A J Timothy Jull; Joellen Russell; Antra Priyadarshi; Mang Lin; Mark Thiemens; Dana Biddulph

doi:10.1016/j.scitotenv.2019.06.372

Measurements of ¹²⁹I in the Pacific Ocean at Scripps Pier and Pacific Northwest sites: A search for effects from the 2011 Fukushima Daiichi Nuclear Power Plant accident and Hanford

Sci Total Environ. 2019 Nov 1:689:1023-1029. doi: 10.1016/j.scitotenv.2019.06.372. Epub 2019 Jun 24.

Authors

Ching-Chih Chang¹, George S Burr², A J Timothy Jull³, Joellen Russell⁴, Antra Priyadarshi⁵, Mang Lin⁵, Mark Thiemens⁵, Dana Biddulph⁶

Affiliations

¹ University of Arizona AMS Laboratory, University of Arizona, Tucson, AZ, USA; Department of Geosciences, University of Arizona, Tucson, AZ, USA.
² University of Arizona AMS Laboratory, University of Arizona, Tucson, AZ, USA; Department of Geosciences, National Taiwan University Research Center for Future Earth, Taipei, Taiwan.
³ University of Arizona AMS Laboratory, University of Arizona, Tucson, AZ, USA; Department of Geosciences, University of Arizona, Tucson, AZ, USA; Isotope Climatology and Environmental Research Centre, Institute for Nuclear Research, Debrecen, Hungary. Electronic address: jull@email.arizona.edu.
⁴ Department of Geosciences, University of Arizona, Tucson, AZ, USA.
⁵ Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA, USA.
⁶ University of Arizona AMS Laboratory, University of Arizona, Tucson, AZ, USA.

PMID: 31280148
DOI: 10.1016/j.scitotenv.2019.06.372

Abstract

Radionuclides from the Fukushima Daiichi Nuclear Power Plant were released directly into the ocean as a result of the Great East Japan Earthquake on March 11, 2011. This material became entrained in surface ocean currents and subsequently transported for great distances. In June 2011, a few months after the disaster, we began a surface ocean ¹²⁹I monitoring program, with samples from Scripps Pier, La Jolla, California, USA, with the expectation that surface currents originating off the east coast of Japan would eventually carry radionuclides to the La Jolla site. After 7 years of ocean transport, a distinct signal has not yet arrived at Scripps Pier. We have however, recorded an interesting systematic seasonal ¹²⁹I time series record that stems from surface circulation variations along the California coast. To provide a more comprehensive picture of the ¹²⁹I budget in coastal surface waters off the west coast of the U.S., we also include ¹²⁹I data from the Columbia River, and offshore sites along the coast of Washington State. Anthropogenic nuclides are carried by the Columbia River into the Pacific Ocean from the vicinity of the decommissioned Hanford nuclear facility. We find highly elevated ¹²⁹I/¹²⁷I values in the Columbia River, downstream from the Hanford site, but this anthropogenic ¹²⁹I becomes significantly diluted once it reaches the Pacific Ocean. Nonetheless, its imprint persists in surface seawater off the west coast of the U.S. that has significantly higher ¹²⁹I/¹²⁷I levels than other surface sites in the Pacific Ocean.

Keywords: Fukushima; Iodine-129; Ocean transport; Radionuclides.