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Study of sea life shows exposure to tritium +increase in temp may increase DNA mutation

Rising temperatures could accelerate radiation induced DNA effects in marine mussels

Increased sea temperatures could dramatically enhance and accelerate radiation-induced DNA effects in marine invertebrates, a new study suggests.

Led by Plymouth University, in conjunction with the Centre for Environment, Fisheries and Aquaculture Science (Cefas), the research for the first time explored the impact of rising temperatures coupled with the presence of tritium, an environmentally relevant radionuclide, on marine mussels (Mytilus galloprovincialis).

Studies carried out under laboratory conditions demonstrated that at radiation dose rates considerably below the recommended international guidelines, induced DNA strand breaks appeared earlier at higher temperature compared to lower temperature. At 15ºC, DNA damage was only significantly elevated after seven days in contrast to 25°C where a similar response was observed after three days.

Scientists involved say this suggests an acceleration of radiation-induced DNA damage and potentially compromising defence mechanisms as indicated by changes in expression profiles of genes involved in heat-shock protection, cell cycle progression and repair of DNA breaks.

Temperature is an abiotic factor of particular concern for assessing the potential impacts of radionuclides, many of them having very long half-lives, on marine species, and with sea surface temperatures forecast to rise 0.5-3.5?C in the next 30-100 years, determining the interaction of radiological exposure has never been more important.

Awadhesh Jha, Professor of Genetic Toxicology & Ecotoxicology, led the study and said: “Ionising radiations are known to induce genetic damage, and radiation-induced genetic damage could be modified by many environmental factors, including temperature. Compared to other radionuclides, large amounts of tritium are discharged, mostly as water, in the marine environment by nuclear power plants (NPPs) and nuclear fuel reprocessing plants (NFRPs). In addition, cooling water from nuclear installations is one of the major sources of tritium in the aquatic environment. As thermal discharges from nuclear facilities is an important environmental issue, second only to the release of radionuclides which could extend for a long distance from the discharge point, such studies are important in determining the hazard and risk to the natural biota and therefore environmental sustainability.”

Brett Lyons, from the Environment and Animal Heath group based in Cefas’ Weymouth laboratory, co-supervised the study and said: “These results are important as they allow us to better understand the risks a warming ocean poses to marine life. We already know climate change is impacting things such as fish physiology, reproduction and migration, but this research is part of a growing body of evidence that is suggesting rises in sea water temperature may increase the risk posed by certain chemical and physical pollutants.”

For the study, published in the Journal of Environmental Radioactivity, the mussels were exposed to tritiated water (HTO) with differing temperatures of 15°C and 25°C, and DNA damage and gene expressions were determined along with accumulation of tritium in different tissues of the mussels over a period of seven days.

In their conclusion, the authors say: “This study is the first to investigate temperature effects on radiation-induced genotoxicity in an ecologically representative marine invertebrate. It represents an important step forward in radioecology in general, and our study suggests that mussels (or similar marine species) exposed to increased temperature and HTO may have a compromised ability to defend against genotoxic insult at the molecular level. This is particularly pertinent in the context of rising sea temperatures and thermal pollution. The study suggests there is still a pressing need to investigate the interactive effects of temperature and other abiotic factors in conjunction with radiation exposure on aquatic organisms.”

Journal Reference:

  1. Lorna J. Dallas, Tim P. Bean, Andrew Turner, Brett P. Lyons, Awadhesh N. Jha. Exposure to tritiated water at an elevated temperature: Genotoxic and transcriptomic effects in marine mussels (M. galloprovincialis). Journal of Environmental Radioactivity, 2016; 164: 325 DOI: 10.1016/j.jenvrad.2016.07.034

August 24, 2016 Posted by | radiation | , , , | Leave a comment

Microscopic particles in oceans – From Fukushima to the USA in 1277 days


A new study published in Nature Communications reveals the global dispersal of plankton, but also provides insights for distribution of plastics, radioactive material and other pollutants.

New study in Nature Communications models global connectivity of the entire planet’s ocean surface

The distance between Fukushima and the west coast of the United States is about 8700 kilometres. If microscopic particles – like phytoplankton or radioactive isotopes – were to travel that fifth of the world’s circumference, it seems like that would take ages.

However, the world is not so big after all, since that is not actually the case.

A new study co-authored by centre researcher, James Watson, recently published in Nature Communications found that the earth’s global surfaces are highly connected.

By investigating the largely underexplored and rarely quantified mechanisms of global surface connectivity, Watson and his co-author Bror Jonsson from Princeton University found that microscopic particles can reach all regions of the ocean in only a decade.

This study emerged from contrasting camps of ideas about planktonic community dispersal in ocean ecosystems: one suggesting that everything is connected and environmental conditions decide where species live; another proposing that spatial isolation leads to genetically distinct species; and another suggesting that both of those ideas fail to tell the whole story.

On top of that, the time it takes for planktonic communities to travel around the ocean surface is a question that is still largely unresolved.

“These short surface-connection times are relevant to anyone studying dispersion in the surface ocean beyond planktonic species, including radioactive materials, plastics and other forms of pollution”

James Watson, co-author

Modeling global surface current connectivity
To tackle these inconsistencies in understanding and questions about time, Watson and his co-author create a model to track particles moving across the global ocean surface. To do this they use a number of different concepts and techniques.

This study uses minimum connection time, the fastest time that particles can travel from one location to another, instead of the commonly used expected connectivity time, which uses mean travel time. Watson notes there are two advantages to this approach.

“Minimum connection time is a more appropriate metric for phytoplankton and bacterial connectivity since asexually reproducing organisms have high reproductive output that attenuates low dispersal probabilities. Additionally, mean transit times in the global ocean are not well defined, as water can recirculate eternally and, hence, every particle seeded in a given patch eventually will reach all other patches if enough time is provided,” explains Watson.

Calculating minimum connection times from Lagrangian particle tracking, a method for understanding computational fluid dynamics, the authors described the global ocean as a network “with patches in the ocean as nodes and minimum connection times as edges connecting the nodes.”

The authors then considered each patch pair and multi-step connections, or in other words particles traveling along a number of patches, and applied Dijkstra’s algorithm, commonly used for finding the shortest path between nodes, to create a network of minimum connection times between every region of the ocean’s surface.

The authors point out that while this global network does account for timescales of physical connectivity, they do not account for environmental factors which undoubtedly play a role in connectivity.


Radioactive reality
While the idea for this study emerged from tiny plankton, the results have blue whale-sized relevance for other ocean surface traveling objects.

Furthermore, these results could in the future help us understand and prepare for how long it takes harmful particles to connect across the globe – like from Fukushima to western United States, or plastics aggregating along the coasts.

“A real example is the 2011 Fukushima disaster, in which a Japanese nuclear reactor released a large quantity of radioactive isotopes into the Pacific Ocean. Traces of radioactivity were detected on the Pacific Coast of the US in November of 2014 – 3.6 years later. Our estimated minimum connectivity time between the Fukushima release site and its detection site of the US west coast is 3.5 years,” explains Watson, an indirect verification of their method.

From a planktonic perspective, the results suggest that planktonic communities may be able to keep pace with climate change by changing locations to better suit their preferred environmental niche.

In a bigger global perspective, Watson concludes that these results, “quantify the effects of global-scale dispersal on how marine communities can adapt to their changing ocean environment.”

The timescales of global surface-ocean connectivity

From Fukushima to the USA in 1277 days

Global surface-ocean connectivity

April 22, 2016 Posted by | Fukushima 2016 | , , , , | Leave a comment