Long-Lived Radionuclides in the Surface Environment (LO-RISE)- Mechanistic Studies of Speciation, Environmental Transport and Transfer

Lead Research Organisation: University of Edinburgh
Department Name: Sch of Geosciences


The impact of radioactivity on humans and the wider environment is controlled by the behaviour of the radionuclides in groundwaters, soils and sediments, and this behaviour is dictated by the quantities of radionuclides, and their chemical forms. We will study some of the radionuclides which are particularly important because they are potentially present in relatively large quantities, are environmentally mobile, and are readily taken up by living organisms. The main radionuclides we are going to study are:

Carbon-14, which occurs in nature, but was produced back in the 1960s and 60s through nuclear weapons testing, and is also present in nuclear wastes; and

Uranium (together with its decay product radium) which is present in nature, and also in some nuclear wastes.

We will use four areas of the UK which contain elevated levels of these radionuclides as our study sites. These are South Terras (an old uranium mine in Cornwall), the Needle's Eye (a uranium mineral vein in SW Scotland), the Esk Estuary in NW England, and offshore sediments in the NE Irish Sea. At these last two sites, the sediments contain elevated levels of radioactivity from authorised Sellafield discharges, mainly in the 1970s.

As well as studying how radioactivity occurs in, and moves through, the soils, waters, plants and (in the offshore sediments) animals, we want to understand the environmental and biological processes which control this movement. To do this, we will do a series of laboratory experiments, looking at the way soil/sediment conditions influence the radionuclide concentrations in solution, the form of the radionuclides in the solution, the way radionuclides are taken up into plants and animals, and the way they are distributed in plant tissues.

We will use the results from our field and laboratory studies to develop and test mathematical models of radionuclide transport and transfer processes. These are important because they allow us to predict behaviour, rather than having to make measurements. These predictive models can be used in assessing environmental impacts, cleaning up contaminated land and predicting the long term impact of radioactive waste disposals.

Planned Impact

The risk of nuclear industry operations is always a major concern. Whether or not these perceptions of risk are justified, they influence the public and decision-makers very heavily. Moreover, there are major uncertainties associated with radioactivity and the environment, which may lead to a very conservative approach to risk. These conservatisms can lead to overestimation of risk, and costly over-engineering of projects. A proportionate understanding of risk in any nuclear programme is therefore essential for public acceptance, political support and proper cost-detriment analysis. Ultimately, the behaviour of radionuclides in the biosphere dictates the radiological risk they represent, and LO-RISE will substantially improve our understanding of this risk, and of conservatisms in risk assessments, so any organisation with responsibilities for assessing or limiting radiological impact will benefit from LO-RISE.

Two distinct groups of beneficiaries can be identified:

1. Government, Industry, and Regulators. Government sets policy for the UK nuclear industry and has clearly stated that the "safety and security of nuclear power is of paramount concern". Our findings will be disseminated both through our project partners and also by LO-RISE academics' involvement in policy and strategy activities, so that LO-RISE will inform and improve policy making. The owners and operators of nuclear licensed sites (NDA, its Site Licence Companies, MOD and its contractors), the implementers of geological disposal (NDA-RWMD); and the nuclear industry regulators (primarily EA in England and Wales, SEPA in Scotland, though ONR may also have an interest), are responsible for delivering Government's policy objectives, and LO-RISE will support development and delivery of Site Lifetime Plans, or equivalent. At the operational level, the nuclear industry relies heavily on a very diverse supply chain. LO-RISE will help these contractors develop and implement improved solutions at the project level, for deployment in the UK and overseas.

2. The Wider Stakeholder Community, and the Public. Even in 'nuclear' communities, new nuclear projects are controversial. This is clearly illustrated by, for example, 'Stop Hinkley' or the controversy around the MRWS process in west Cumbria. Objective research has a vital role in providing trusted information to inform these debates, and LO-RISE will contribute to this through specifically tailored outreach and impact activities.
Description In the first year of the grant, training for the PhD student has been provided and initial geochemical characterisation of the sampling sites has been undertaken.
Novel methods for NMR characterisation of humic substances have also been developed and resulted in a publication in Chemical Communications.
In the second year of the grant, considerable progress has been made in the area of uranium speciation in the highly organic-rich solid phase at the Needle's Eye site, SW Scotland. It is clear that oxidised forms of uranium persist even under extremely reducing conditions. Several publications are being planned.
A second NMR paper was published in Angewandte Chimie (2015) demonstrating the facility of multidimensional NMR methods to unambiguously characterise individual organic molecules in highly organic-rich soils. Some of these can be linked to specific plant sources.
A third NMR paper was published in the RSC journal Analytical Chemistry (2016) and this gives explains in detail the approach to achieving unambiguous structural characterisation of individual organic molecules within complex mixtures.
Research focus in the third year of the project has focused on developing methods to isolate and reproducibly fractionate organic matter without changing or contaminating the resulting materials. A suite of spectroscopic methods have then been employed to characterise these fractions to reach a consistent and detailed view of structural changes occurring with vertical depth in both organic-rich soils and organic-poor sediments. Stable carbon isotopes have been used to identify changes in source of the organic material and AMS has yielded information about the radioacarbon content of organic matter fractions. The more marine material has a greater proportion of radiocarbon, consistent with the release of dissolved inorganic carbon into the Irish Sea and its subsequent incorporation into plankton-derived organic matter.
A fourth paper on identifying organic compounds using mass spectrometry was published in 2017 and this compares different ways in which samples can be analysed and the impacts that these might have on the results obtained. An understanding of how the instrumental approach may influence the nature of the identified compounds is imperative when interpreting these results in the wider environmental context.
Additional papers on the speciation of uranium (oxidation state) and on its associations with organic matter in soils are in preparation or nearing submission.
Exploitation Route Close collaboration within the consortium is ongoing and our direct geochemical characterisation of field samples will be fully integrated with laboratory manipulations of the same materials that are planned for year 3 of the programme.
The NMR publication will be of use to others working with complex mixtures of natural organic compounds and those carrying out industrial processes where natural organic compounds can cause problems, e.g. waste water treatment, drinking water treatment. The mass spectrometry publication will also be useful to those working with complex mixtures of natural organic compounds but also to those working on removal of such compounds from drinking water.
Sectors Agriculture, Food and Drink,Energy,Environment,Other

URL http://www.readcube.com/articles/10.1039/C3CC48907H
Description The ability to characterise individual compounds within complex mixtures has applications for analysis in food/drinks industry and also in water treatment industry. Follow-on projects with drinks companies and with water companies (e.g. Scottish Water) are underway. There is potential to detect new and emerging organic contaminants in waters and we will work with companies and consultancies in the area of environmental risk assessment.
Sector Agriculture, Food and Drink,Chemicals,Environment,Healthcare,Pharmaceuticals and Medical Biotechnology,Other
Impact Types Economic,Policy & public services