ken buesseler - fukushima - a view from the ocean
DESCRIPTION
Presentation from Safecast: The Next Three Years symposium, March 15, 2014TRANSCRIPT
Fukushima – a view from the ocean Ken Buesseler, Senior Scientist
Woods Hole Oceanographic Institutionhttp://cafethorium.whoi.edu
Yokohama June 2011 Daisan Kaiyu Maru Sept 2013
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
Cesium is soluble in seawater
137Cs half‐life = 30 years134Cs half‐life = 2 years
Ken BuesselerWHOI
We live in a radioactive world (and ocean)
1 Bq = 1 Becquerel = one radioactive decay per second1 PBq = peta‐Becquerel = one million billion Bq
1015 Bq = 1,000,000,000,000,000 Bq
What are levels of cesium‐137 in ocean prior to Fukushima?
Range from <1 to >60 Bq m‐3
Higher in Baltic and Black Seas due to Chernobyl & Irish Sea due to Sellafield
Sources of Fukushima radionuclides to the ocean
Atmospheric deposition
1
Mid‐March2011
Direct discharge2
Early April 2011 peaknow small and continues
Through river runoff3
Through underground water flow
4
small and continues
small and continues Y. MasumotoJAMSTEC
One year history of cesium‐137 in ocean off Fukushima
Levels priorto March 11
At nuclear power plant Ocean Cs levels peak on April 6th‐ possible reproductive effects and mortality for marine biota
Levels of concern for seafood
Highest ocean levels post Chernobyl
US drinkingwater limit
Fukushima is an unprecedented event for the ocean
levels highest in 2011, then leveled off
reactor site remains a source
levels now safe for marine biota & human exposure
still concern for seafood?
one banana
April 1 June 1 Aug 1 Oct 1 Dec 1 Feb 1 ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ 2011 ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ ‐‐‐‐2012‐‐‐
Data from TEPCO Buesseler et al., 2012
Japan regulatory limit
134Cs varies by 3 orders of magnitude‐ up to 4000 Bq m‐3
134Cs 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
134Cs in ocean‐ June 2011
134Cs t1/2 = 2 yr>99.5% soluble
10100
1,00010,000
100,0001,000,000
10,000,000100,000,000
3/18/11 10/4/11 4/21/12 11/7/12 5/26/13 12/12/13
137 C
s (B
q/m
3 )
Cesium source continues at Fukushima Dai‐ichi
Evidence includes TEPCO reporting Independent ocean studies Seafood monitoring
What about surface ocean cesium‐134 in May 2013
134Cs indicates continued source at NPP
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)
Max =45 Bq m‐3
Buesseler, Yoshida et al, unpublished
What about Fish and cesium accumulation?
information page from Japanese Ministry of Agriculture, Forestry and Fisheries (MAFF)
Cesium uptake and loss from fish is rapid
50% loss in 50 days
Data from Japan FisheriesFigure adapted from Buesseler, Science, 2012
Fisheries closed offFukushima
Elevated Cs consistentwith continued sources
Tbq = 1012 Bqadapted from J. Kanda
How big is NPP source today?
For cesium isotopes Total today = 0.3 TBq/mo (1 TBq = 1012 Bq) Source in March/April 2011 = 10‐30,000 TBq/mo
For strontium‐90 Total today = 0.1 TBq/mo? Source in March/April 2011 = 100 TBq/mo
At NPP, Cs is actively being removed from cooling water, and naturally sorbed to sediments, while 90Sr and tritium are not w/diversion of groundwater, salt water intrusion could lead to Cs
remobilization w/leaking tanks, large potential 90Sr source
Each tank= 300 tons x 40 x 106 Bq/L = 12 TBq
Predicted surface ocean 137Cs
April2012
April2014
ArrivalN. US Coast& Hawaii
Seattle
San Diego
How long until cesium reaches US west coast?
2014
Arrives 2013‐2014 (after debris) Predicted 137Cs off US varies from 1‐2 to 30 Bq m‐3
Levels are low for exposure & fisheries US public concern but no government monitoring
Rossi et al., DSRI, 2013
In response, launched citizen scientist crowd funding siteJan. 14, 2014
url‐ http://ourradioactiveocean.org email‐ [email protected]
First 2 month’s successstories
Public attention high
>55,000 views
30 sampling sites in progress
>215 donors
$28K raised
No 134Cs YET along US west
coast
Our Radioactive Ocean SUPPORTERS Alaska Ocean Observing SystemBamfield Marine Science CentreDavid Suzuki FoundationDeerbrook Charitable TrustGordon and Betty Moore FoundationGwaii Haanas National Park Reserve,
Parks CanadaHumboldt State University, Marine LabKUSP Santa CruzMothers for Peace of San Luis ObispoOnset ComputerPacific Blue FoundationPoint Blue Conservation SciencePrince William Sound Science CenterSanta Barbara Channel KeeperSay Yes! to Life Swims LLCScripps Institution of OceanographyTopanga Wildlife Youth ProjectUniversity of California Davis, Marine
Pollution Studies LabUniversity of Guam Sea GrantUniversity of HawaiiWoods Hole Oceanographic Institution& thanks to more than 160 concerned citizens who have made donations!