By Jay T. Cullen
Previously unpublished data results from research expeditions in 2014 and 2015 are summarized here. Overall the data indicate that:
- Fukushima derived radiocesium was first detected 1500 km west of British Columbia Canada in June 2012
- Contamination was detected on the continental shelf (near coastal waters) in June 2013
- By February 2014 Fukushima radiocesium was present at levels similar to preexisting weapons testing derived 137Cs
- The timing of the arrival and levels of radiocesium in the contaminated plume are in reasonable agreement with existing ocean circulation model predictions
- 134Cs, a unique indicator of Fukushima impact given its ~ 2 year half life, increased in 2014 and 2015 relative to previous years indicating that peak concentrations are likely to arrive in 2016
- Maximum combined radiocesium activities (137Cs + 134Cs) offshore as of summer 2015 are 11 Bq m-3 of seawater are about 8-10 fold less than maximum activities measured in the 1960’s due to weapons testing fallout. Current levels do not represent a significant risk to ecosystem or public health