The effects of ionising radiation on soil communities

Overview

It is suspected that ecological interactions, adaptation and transgenerational effects of radiation combine to cause net changes in ecosystem structure (e.g. population densities, community composition and biodiversity). Changes in ecosystem structure will have implications for ecosystem function (e.g. nutrient cycling) and consequently services. The soil ecosystem is a component of any terrestrial environment. To date, studies of the effects of radiation on soil ecosystem have looked at individual species (e.g. earthworms) or processes such as leaf litter decomposition. The system as a whole has not been adequately studied.

Using mesocosms (controlled mini-ecosystems) housed in a controlled irradiation facility, this project will investigate the effect of ionising radiation on soil ecosystem structure and function. In particular, it will study how two to three species respond within the mesocosm both singularly and in combination. As well as traditional methods of analysing impacts, the project will include metabarcoding, transcriptomics and functional gene analysis to examine microbial and fungal community structure and function and to characterise changes in the microbiomes of key species in both microcosms, as these are highly relevant key processes.

Following on from the experimental work, the project will model the mesocosm findings to assess a) What does response to radiation mean for the overall ecosystem if interacting species have different capacities to adapt to radiation? b) Are there tipping points beyond which some populations or communities could go extinct while others thrive; if so, what is the consequence for ecosystem function? c) How are responses at these tipping points affected by species’ capacity to adapt to radiation or to deal with environmental and ecological factors?

There will be the opportunity to test hypotheses derived from laboratory experiments and the modelling work within the Chernobyl exclusion zone. The project will feed into the work of other organisations such as the International Commission on Radiological Protection and national regulators.

Methodology

Standard guidelines for successful mesocosm experiments will be followed. The mesocosms will be set up for long term continuous exposures in the radiation facility at Stirling. At regular intervals, samples and measurements will be taken and analysed for a range of different parameters to quantify changes in ecosystem structure and processes such as nutrient cycling and carbon sequestration that underpin ecosystem services whether due to direct or indirect radiation effects. As well as traditional methods of assessing the impacts of ionising radiation, we will include metabarcoding, transcriptomics and functional gene analysis to examine microbial and fungal community structure and function and characterise changes in the microbiomes of key species.

Computer models will be developed and used to test scenarios of how different population densities and species interactions may lead to different population level effects and changes in ecosystem function. This will be explored in collaboration with modelling activities being undertaken within the United Nations International Atomic Energy Agency.

Project Timeline

Year 1

Funding is available for 3.5 years.

In year 1, the student will conduct a literature review and design an appropriate research strategy for work within the radiation facility and laboratory (soil mesocosm) studies;

Learn how to culture and/or maintain a variety of micro-organisms for use in the soil mesocosms;

Undergo training in metabarcoding, transcriptomics and functional gene analysis;

Attend and present at one national conference (probably COGER – the Coordinating Group on Environmental Radioactivity);

Introduction to the International Atomic Energy Agency modelling work that is exploring how best to use computer modelling techniques to better understand radiation effects.

Year 2

Undertake and analyse the results from laboratory based radiation exposure experiments in the Stirling irradiation facility.

Undergo training in computer modelling approaches and apply these techniques using the data collected from the laboratory experiments.

Start writing up the first chapters based on the literature review and the experimental work.

Attend and present at one national conference.

Participate in International Atomic Energy Agency modelling work that is exploring how best to use computer modelling techniques to better understand radiation effects.

Year 3

Repeat laboratory experiments to test any hypotheses developed from the computer modelling work. Undertake fieldwork in the Chernobyl Exclusion Zone to test the computer modelling predictions.

Continue to write up with the intention to have the first 2-3 chapters completed by the end of year 3.

Continue to participate in International Atomic Energy Agency modelling work that is exploring how best to use computer modelling techniques to better understand radiation effects.

Attend and present at one national (e.g. COGER) and one overseas conference (e.g. ICRER – the International Conference on Radioecology and Environmental Radioactivity.

Year 3.5

Thesis finalisation and paper writing (although it is anticipated that these activities will be ongoing throughout the PhD).

Training
& Skills

The analytical and mathematical techniques required for this study are already established at the University of Stirling and CEH and include: use of radiation in the controlled facility, conventional assessment of radiation effects (Stirling), metabarcoding, transcriptomics and functional gene analysis (CEH) and computer modelling (both organisations).

The successful applicant will receive training in experimental design, data analysis, and radiological protection related to the project work. They will attend classes on Effective Research, Scientific Writing, Statistics for Environmental Evaluation (and use of R), Presentation Skills, and Radiological Environmental Protection. They will spend time at CEH for training in metabarcoding, transcriptomics and functional gene analysis.

The student will also benefit from wider interaction within research groups at Stirling and CEH Lancaster. We will establish regular meetings via Skype between CEH and Stirling to allow discussions on the student’s work. They will be expected to present the results of their research annually at the BES student symposium and to attend the annual UK COGER meetings which have an emphasis on encouraging students to present their work. The student will also be expected to present their work at one international conference. The student will have the opportunity to interact with wider student networks (and training opportunities) though the European Radioecology ALLIANCE.

References & further reading

Alonzo F., Hertel-Aas T., Real A., Lance E., Garcia-Sanchez L., Bradshaw C., Vives i Batlle J., Oughton D.H. and Garnier-Laplace J. (2016) Population modelling to compare chronic external radiotoxicity between individual and population endpoints in four taxonomic groups. Journal of Environmental Radioactivity. 152: 46-59.

Beresford, N.A., Copplestone, D. (2011) Effects of Ionizing Radiation on Wildlife: What Knowledge Have We Gained Between the Chernobyl and Fukushima Accidents? Integer. Environ. Ass. Manag., 7, 371-37.

Bonzom J-M. et al. (2016) Effects of radiation contamination on leaf litter decomposition in the Chernobyl exclusion zone. STOTEN 15: 596-603.

Copplestone, D., Beresford, N.A., Howard, B.J. (2010) EDITORIAL: Protection of the Environment from Ionising Radiation: developing criteria and evaluating approaches for use in regulation. J. Radiol. Prot., 30, 191-194.

Møller & Mousseau (2006) Biological consequences of Chernobyl: 20 years on. Trends Ecol Evol. 21:200-207.

Wardle (2002) Communities and ecosystems: linking the aboveground and belowground components.

Sazykina T.G. (2018) Population sensitivities of animals to chronic ionising radiation-model predictions from mice to elephants. Journal of Environmental Radioactivity. 182: 177-182.

Zaitsev et al (2014) Ionizing radiation effects on soil biota: Application of lessons learned from Chernobyl accident for radioecological monitoring. Pedobiologia. 57:5-14 .
http://tiny.cc/0r1m6y

Further Information

David Copplestone +44 (0)1786 467852, Email: david.copplestone@stir.ac.uk
Nick Beresford +44 (0)1524 595856, Email: nab@ceh.ac.uk

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