Presence of 236U and 239,240Pu in soils from Southern Hemisphere

²³⁶U, ²³⁹Pu and ²⁴⁰Pu are present in soils mainly as a result of the local- and global-fallout from the atmospheric nuclear weapons tests carried out mainly in the 1950's and 1960's. In this work we provide new data on the presence of ²³⁶U and ^239,240Pu in surface soils (i.e. up to 5 cm depth) from Chile and Africa. The results were obtained by low-energy Accelerator Mass Spectrometry (AMS). In the case of the Chilean samples, ²³⁶U/²³⁹Pu atom ratios show a high variability and are in general higher than the reported value for the global fallout in the Northern Hemisphere, ranging from 0.2 to 1.5. The ²³⁶U atomic concentrations range from 3.5 × 10⁶ to 9.1 × 10⁶ atoms/g, and are at least two orders of magnitude lower than the reported values in the Northern Hemisphere. The measured ²⁴⁰Pu/²³⁹Pu atom ratio in soils from South-Africa and Mozambique are of about 0.17, in agreement with the expected one for global-fallout at those coordinates. To best knowledge of the authors the present work is the first publication on ²³⁶U concentrations and ²³⁶U/²³⁹Pu atom ratios in soils from South-America and Africa.

Marine radioecology after the Fukushima Dai-ichi nuclear accident: Are we better positioned to understand the impact of radionuclides in marine ecosystems?

This paper focuses on how a community of researchers under the COMET (CO-ordination and iMplementation of a pan European projecT for radioecology) project has improved the capacity of marine radioecology to understand at the process level the behaviour of radionuclides in the marine environment, uptake by organisms and the resulting doses after the Fukushima Dai-ichi nuclear accident occurred in 2011. We present new radioecological understanding of the processes involved, such as the interaction of waterborne radionuclides with suspended particles and sediments or the biological uptake and turnover of radionuclides, which have been better quantified and mathematically described. We demonstrate that biokinetic models can better represent radionuclide transfer to biota in non-equilibrium situations, bringing more realism to predictions, especially when combining physical, chemical and biological interactions that occur in such an open and dynamic environment as the ocean. As a result, we are readier now than we were before the FDNPP accident in terms of having models that can be applied to dynamic situations. The paper concludes with our vision for marine radioecology as a fundamental research discipline and we present a strategy for our discipline at the European and international levels. The lessons learned are presented along with their possible applicability to assess/reduce the environmental consequences of future accidents to the marine environment and guidance for future research, as well as to assure the sustainability of marine radioecology. This guidance necessarily reflects on why and where further research funding is needed, signalling the way for future investigations.

Anthropogenic 236U and 129I in the Mediterranean Sea: First comprehensive distribution and constrain of their sources

The first basin-wide distribution of ²³⁶U/²³⁸U atom ratios and ¹²⁹I concentrations is presented for the Mediterranean Sea. During the GEOTRACES GA04S-MedSeA expedition in 2013 seawater was collected from 10 vertical profiles covering the principal sub-basins of the Mediterranean Sea. The main objective was to understand the distributions of ²³⁶U and ¹²⁹I in relation to the water masses, and to constrain their sources in this region. The ²³⁶U/²³⁸U atom ratios and the ¹²⁹I concentrations ranged from (710±40)×10^-12 to (2220±60)×10^-12 and from (4.0±0.1)×10⁷ to (13.8±0.3)×10⁷at·kg^-1, respectively. The results show that radionuclide-poor Atlantic Water is entering at the surface through the Strait of Gibraltar whereas comparably radionuclide-enriched Levantine Intermediate Water is sinking in the Eastern Basin and flowing westward at intermediate depths. Low radionuclide levels were found in the oldest water masses at about 1000-2000m depth in the Eastern Basin. At greater depths, waters were relatively enriched in ²³⁶U and ¹²⁹I due to dense water formation occurring in both, the Eastern and Western Basins. The inventories of ²³⁶U and ¹²⁹I cannot be explained only by global fallout from atmospheric nuclear bomb testings carried out in the 1950s and 1960s. We estimate that the liquid input of ²³⁶U from the nuclear reprocessing facility of Marcoule (France), via the Rhône river, was of the same order of magnitude than the contribution from global fallout, whereas liquid and gaseous releases of ¹²⁹I from Marcoule were up to two orders of magnitude higher than global fallout. For both radionuclides, the contribution from the Chernobyl accident is found to be minor.

Hepatitis A infections in Wisconsin: trends in incidence and factors affecting surveillance, 1986-1995

From January 1986 through December 1995, 4,143 cases of hepatitis A virus (HAV) infection were reported in Wisconsin. The annual hepatitis A incidence remained stable from 1986 through 1988, with a mean annual rate of 4.7 cases per 100,000 (endemic HAV incidence rate). During 1989-1993, the incidence of HAV infection increased with a peak in 1992 of 19 cases per 100,000 population. A large foodborne outbreak (1992) and community wide outbreaks among African American residents (1989-1993) and Native Americans residents (1991) were associated with these high rates of HAV infection. The community wide outbreaks affected different groups: among African Americans, incidence rates were highest in young adults 15-34 years old; among Native Americans rates were highest in children 5-14 years old. Approximately 2,343 (57%) patients had no apparent risk factor (e.g., international travel, contact with person with HAV infection) for acquiring HAV infection. Factors limiting control of HAV infection in Wisconsin included poor reporting by laboratories (only 19% of all reported cases were independently reported to the Wisconsin Division of Health by a laboratory and fewer than 50% of these reports were from private laboratories), incomplete reporting by Wisconsin physicians or designees (74% of cases confirmed in Wisconsin laboratories were reported in 1995), failure to submit follow-up case report forms (14% of cases), and a prolonged interval between diagnosis and follow-up (> or = 15 days for 610 cases). Efforts should be enhanced to improve the reporting of cases of HAV infection by private laboratories, particularly through the use of automated electronic reporting.

Correlation of electrical and contractile activities of the cricopharyngeus muscle in the cat

We correlated the electrical and contractile activities of the cricopharyngeus (CP) to better understand the function of the CP and the upper esophageal sphincter (UES). In 40 decerebrate cats, we recorded resting and active tension of the CP and CP force and electromyographic (EMG) activity simultaneously during electrical stimulation of the pharyngoesophageal (PE) nerve, esophageal distension, or swallowing. In six intact cats, the change in diameter of the UES during food swallows was determined in two planes using videofluoroscopy. We found that resting tension of the CP developed quickly with stretch, and the strain-energy function, y = 6.5e3.4(z-1), fit (r = 0.94 +/- 0.06) this relationship. Active tension peaked at 1.68 +/- 0.03 times resting length, which is greater than the maximum distension during swallowing. Activation and relaxation of the CP occurred in approximately 50 and 120 ms, respectively. PE nerve stimulation bilaterally caused a force equal to approximately 90% of the summed force generated by separate stimulation of each PE nerve. The magnitude of the EMG response of the contralateral CP was approximately 18% of the ipsilateral response to unilateral PE nerve stimulation. We conclude that the CP exhibits tension throughout its physiological range of stretch. The CP functions more like a bilateral than a single contiguous muscle, and more like cardiac than striated muscle with regard to its passive elastic properties.