Radiation levels in fresh water samples at Fukushima Daiichi have been going up, rather than down. Contaminated ground water at the site is pouring into the ocean at an officially reported rate of 300-400 tons daily:
Ground water contamination is extraordinarily high, with the well between the ocean and unit 1 measuring a record 5 million becquerels per liter of radioactive strontium-90 alone in July 2013. TEPCO stated the total bequerels per liter is likely 10 million when all beta ray sources are included.
TEPCO had originally interpreted the July 2013 beta tests as indicating 700,000 becquerel per liter of strontium, but revised the figure upwards to 5 million in February of 2014. The revised figure of 5 million Becquerels per liter of strontium is 170,000 times the permissible level. TEPCO was accused of deliberately withholding extraordinarily high contamination levels.
Trends have been sharply upwards in strontium, tritium and cesium contamination levels across 2014. For example, in October of 2014, TEPCO reported well water samples near unit 2 contained 7.8 million becquerels of beta particle-emitting radioactive substances, such as strontium-90, per liter, also a 3.7-fold increase over Thursday's level (http://jen.jiji.com/jc/i?g=eco&k=2014101400933)
The level of contamination of fresh and sea water is likely to trend upwards for many years because at least one of the melted cores is believed to be located in an underground river at the site. How are radionuclides going to "disperse" in the environment?
In April (3) 2012 The Mainichi reported that “Cesium up to 100 times levels before disaster found in plankton far off nuke plant” and that the “high concentration of cesium, which is believed to derive from the Fukushima No. 1 Nuclear Power Plant, suggests that radioactive substances that have leaked from the complex are spreading extensively in the sea.” The Mainichi (2012, April 3), http://mdn.mainichi.jp/mdnnews/news/20120403p2a00m0na009000c.html
I conducted a historical search for bioaccumulation using the JSTOR index, focusing on the radionuclides known to present the majority sources of radiation derived from nuclear fallout: 241Am, 90Sr, 137Cs, 238Pu, 239Pu, and 240Pu (DOE, 1997, http://www.atsdr.cdc.gov/toxprofiles/tp156-c6.pdf).
Search results from the JSTOR index indicate that bioaccumulation was first studied in the late 1950s by scientists looking at the dispersion of radionuclides in the environment. They tended to be funded by government: for example, Oak Ridge National Laboratory funded research on bioaccumulation of radionuclides in “the marine environment.”
The research cited below finds clear evidence of bioaccumulation of a wide range of radionuclides by aquatic life: Marine organisms concentrate cesium 3-30 times over the levels in the surrounding water, although concentration can be much higher, by two or three orders of magnitude (Polikarpov 1966; Wolfe, 1971), especially in animals situated at the top of the food chain, as modeled by Alva and Gobas for killer whales (Hat Tip Enenews poster but forgot source [sorry]):
Alva, Juan & Gobas, Frank (2011, October 4). Modeling the Bioaccumulation Potential of Cesium-137 in a Marine Food Web of the Northwest Pacific, Canada. Paper presented at SETAC North America 32nd Annual Meeting in Session 498: Environmental Radiation: What Do We Know and What Should We Know for Assessing Risks http://www.researchgate.net/publication/233869698_Modeling_the_Bioaccumulation_Potential_of_Cesium_137_in_a_Marine_Food_Web_of_the_Northwest_Pacific_Canada
Other highly chemically and radiologically genotoxic radionuclides, such as Americium and Plutonium, are highly BIO-AVAILABLE. For example, research conducted by Fisher, Bjerregaard and Fowler (1983) found that Plutonium, Americium, and Californium concentrate readily in marine plankton:
Nicholas S. Fisher, Poul Bjerregaard and Scott W. Fowler (1983). Interactions of Marine Plankton with Transuranic Elements. 1. Biokinetics of Neptunium, Plutonium, Americium, and Californium in Phytoplankton. Limnology and Oceanography, 28(3) (May, 1983), pp. 432-447 Published by: American Society of Limnology and Oceanography. Stable URL: http://www.jstor.org/stable/2835825
“The results suggest that Pu, Cf, and Am would associate with marine particles which could transport them vertically, transfer them into the marine food web, or both”Page 445; Our results are consistent with the hypothesis that the reactive transuranic elements (e.g. Pu, Am, Co are likely to reach an equilibrium between surfaces of suspended particles and ambient seawater and that the adsorptive properties of particles scavenging these (and other) metals are governed by organic coatings (Balistrieri et al. 1981). Phytoplankton particles with associated transuranics may sink slowly, transporting these elements to deeper waters and sediments (Bowen et al. 1980; Santschi et al. 1980), or they may be ingested by herbivores in surface waters. Once ingested, radionuclides may be assimilated into food chains (Lowman et al. 1971; Koide et al. 1981) or defecated in the form of fast-sinking fecal pellets (Higgo et al. 1977).
It is interesting that radionuclides such as Cesium and Americium bioaccumulate in different areas of organisms, and at different concentrations with Americium levels higher than Cesium, as illustrated by this study:
Metian, Marc, Warnau, Michel, Teyssie, Jean-Louis, Bustamante, Paco (2011) Characterization of Am-241 and Cs-134 bioaccumulation in the king scallop Pecten maximus: investigation via three exposure pathways. Journal of Environmental Radioactivity, 102(6), 543-550 DOI: 10.1016/j.jenvrad.2011.02.008
[Abstract] In order to understand the bioaccumulation of Am-241 and Cs-134 in scallops living in sediments, the uptake and depuration kinetics of these two elements were investigated in the king scallop Pecten maximus exposed via seawater, food, or sediment under laboratory conditions. Generally, Am-241 accumulation was higher and its retention was stronger than Cs-134. This was especially obvious when considering whole animals exposed through seawater with whole-body concentration factors (CF7d) of 62 vs. 1, absorption efficiencies (A(0l)) of 78 vs. 45 for seawater and biological half-lives (T-b1/2l) of 892 d vs. 22 d for Am-241 and Cs-134, respectively. In contrast, following a single feeding with radiolabelled phytoplankton, the assimilation efficiency (AE) and T-b1/2l of Cs-134 were higher than those of Am-241 (AE: 28% vs. 20%; T-b1/2l: 14 d vs. 9 d). Among scallop tissues, the shells always contained the higher proportion of the total body burden of Am-241 whatever the exposure pathway. In contrast, the whole soft parts presented the major fraction of whole-body burden of Cs-134, which was generally associated with muscular tissues. Our results showed that the two radionuclides have contrasting behaviors in scallops, in relation to their physico-chemical properties.
Through absorption and adsorption radionuclides in the water column are readily assimilated by phytoplankton, whereupon they are either consumed – resulting in biomagnification – or fall towards the bottom of the ocean.A significant percentage (estimated at about a 1/2 of cellular load) of Pu and Am accumulated by plankton fall to intermediate depths, where they remain suspended, resulting in the “enrichment of waters of intermediate depth with Pu or Am lost from sinking algal cells” (Fisher et al, 1983).
Implications for Testing?
Testing for Cesium alone is an INADEQUATE measure of the toxic load accumulating in ocean flora and fauna. Research should test for Uranium, Americium, Strontium, etc to capture the full range of radionuclides bioaccumulating in ocean life.
Testing surface water is an INADEQUATE measure of ocean contamination. Radionuclides do not indefinitely remain in surface level water because they bind with particles and typically fall to mid ocean strata AND/OR are taken up by aquatic life, whereupon bioaccumulation and biomagnification occur. Across time the highest concentrations of reactive radionuclides are likely to be found in the intermediate water column, not on the surface.
Testing water for Cesium is a start but is INADEQUATE alone. Testing for radionuclides in marine environments must carefully consider the “radiation ecology.” The radiation ecology is the phrase developed out of the early 1950s research on bioaccumulation. It is clear from my research that our government regulation has ignored produces of bioaccumulation in developing exposure guidelines for well over fifty years.