Fukushima a view from the ocean Ken Buesseler, Senior Scientist Woods Hole Oceanographic Institution

Transcription

1 Fukushima a view from the ocean Ken Buesseler, Senior Scientist Woods Hole Oceanographic Institution

2 Fukushima a view from the ocean Ken Buesseler, Senior Scientist Woods Hole Oceanographic Institution Yokohama June 2011 Daisan Kaiyu Maru Sept 2013

3 We live in a radioactive world (and ocean) Natural sources are larger than man made sources Fukushima total still poorly known We can measure less than 1 Bq In the ocean (and human body) different radionuclides have different fate and toxicity 1 Bq = 1 Becquerel = one radioactive decay per second 1 PBq = peta Becquerel = one million billion Bq Bq = 1,000,000,000,000,000 Bq Cesium is soluble in seawater 137 Cs half life = 30 years 134 Cs half life = 2 years Ken Buesseler WHOI

4 What are levels of cesium 137 in ocean prior to Fukushima? Map updated from Buesseler & Livingston 1990 by P. Morris Range from <1 to >60 Bq m 3 Higher in Baltic and Black Seas due to Chernobyl & Irish Sea due to Sellafield

5 Sources of Fukushima radionuclides to the ocean 1 Atmospheric deposition Mid March Through river runoff small and continues 4 Through underground water flow small and continues 2 Direct discharge Early April 2011 peak now small and continues Y. Masumoto JAMSTEC

6 One year history of cesium 137 in ocean off Fukushima At nuclear power plant Ocean Cs levels peak on April 6th possible reproductive effects and mortality for marine biota Fukushima is an unprecedented event for the ocean one banana Levels prior to March 11 US drinking water limit Japan regulatory limit Levels of concern for seafood Highest ocean levels post Chernobyl levels highest in 2011, then leveled off reactor site remains a source levels now safe for marine biota & human exposure April 1 June 1 Aug 1 Oct 1 Dec 1 Feb Data from TEPCO Buesseler et al., 2012 still concern for seafood?

7 134 Cs in ocean June Cs t 1/2 = 2 yr >99.5% soluble 134 Cs varies by 3 orders of magnitude up to 4000 Bq m Cs seen from 30 km out 600 km off shore Highest values associated with near shore eddy Kuroshio acts as barrier (if air deposition to south, not very much) Buesseler et al. PNAS April 2012 data available on line

8 What about surface ocean cesium 134 in May 2013? 134 Cs indicates continued source at NPP Max = 45 Bq m 3 Highest Cs closest to shore, associated with locations of higher groundwater input Lower overall in Sept. than May 2013 but 150 Bq m 3 at 1 km (WHOI) >1 2,000 Bq m 3 at coast (TEPCO) Buesseler, Yoshida et al, unpublished

9 Tbq = Bq adapted from J. Kanda

10 How long until cesium reaches US west coast? Predicted surface ocean 137 Cs April 2012 Seattle San Diego Arrival N. US Coast & Hawaii 2014 April 2014 Rossi et al., DSRI, 2013 Arrives (after debris) Predicted 137 Cs off US varies from 1 2 to 30 Bq m 3 Levels are low for exposure & fisheries US public concern but no government monitoring

11 In response, launched citizen scientist crowd funding site Jan. 14, 2014 url

12 First 2 month s success stories Public attention high >55,000 views 30 sampling sites in progress >215 donors $28K raised No 134 Cs YET along US west coast

13 What is needed next? In response to ongoing leaks at Fukushima An international alliance on research and clean up would help restore shattered public trust Nature editorial Sept 3, 2013 Some encouraging signs "We are wide open to receive the most advanced knowledge from overseas to contain the problem" Japan PM Abe said "My country needs your knowledge and expertise Oct. 6. Kyoto Science Forum But does this invitation go beyond clean up? to environmental and ocean assessments by independent academics? Ongoing remarks from Japan are confusing The situation has been under control as a whole Abe answered Oct. 16, 2013 at Japan DIET opening session reported in Japan Daily Press

14 Fukushima lessons learned from the ocean Fukushima NPP represents unprecedented release of radionuclides to the ocean off Japan Many reasons for study Human health, radioecology, ocean tracers, future accidents Japan is leading studies, but confirmation by international labs will build public confidence (and increase scientific insights) Fukushima NPP site continues to leak radionuclides via groundwater and tanks (strontium 90 concern) Studies of fish are not enough need long term studies of ocean, seafloor, rivers, etc. & new technologies Public remains concerned in Japan and now in US & Canada

15 Thanks to many!