A Risk Management Perspective on Climate Change: Lessons Learned from the Nuclear Industry.

Despite the widely acknowledged role of the anthropogenic drivers of climate change, there has been little success in developing a clear overview of the strengths and weaknesses of counter-measures or developing a consensus on their application. Problems with conventional approaches arise from the strongly coupled, multidisciplinary issues involved and the long timescales (centuries or more) over which some key processes operate. Here we outline an alternative approach based on experience gained in risk assessment for an area with similar challenges-the geological disposal of radioactive waste. Utilization of such risk assessment approaches and tools to facilitate a holistic, top-down synthesis of the interactions between the key features, events and processes driving climate change and constraining responses to it, are illustrated. We especially focus on visual presentations that encourage dialog between both specialists and non-technical stakeholders. These can thus form a basis to assist balancing responses in terms of energy policy, modified socio-economic boundary conditions and environmental management.

Risk management for pandemics: a novel approach: "Hindsight is 20/20" English proverb.

The impacts of the current COVID-19 pandemic illustrate the global-level sensitivity to such threats. As understanding of major hazards is generally based on past experience and there is a lack of good historical precedents, approaches and models currently employed to assess risks and guide responses generally lack transparency and are often associated with huge, unspecified uncertainties. Fundamental challenges arise from the strongly coupled nature of the impacts of a pandemic (i.e. not only on health, but also on the entire socio-economic infrastructure) and their long-term evolution with recovery likely to take many years or, potentially, decades. Here, we outline experience gained in risk assessment within the nuclear industry, which has experience facing similar challenges (assessing long-term impacts in a strongly coupled technical system subject to socio-economic constraints), and assess options for knowledge transfer that may help manage future pandemics and other high-impact threats.

Microbial impacts on 99mTc migration through sandstone under highly alkaline conditions relevant to radioactive waste disposal.

Geological disposal of intermediate level radioactive waste in the UK is planned to involve the use of cementitious materials, facilitating the formation of an alkali-disturbed zone within the host rock. The biogeochemical processes that will occur in this environment, and the extent to which they will impact on radionuclide migration, are currently poorly understood. This study investigates the impact of biogeochemical processes on the mobility of the radionuclide technetium, in column experiments designed to be representative of aspects of the alkali-disturbed zone. Results indicate that microbial processes were capable of inhibiting 99mTc migration through columns, and X-ray radiography demonstrated that extensive physical changes had occurred to the material within columns where microbiological activity had been stimulated. The utilisation of organic acids under highly alkaline conditions, generating H2 and CO2, may represent a mechanism by which microbial processes may alter the hydraulic conductivity of a geological environment. Column sediments were dominated by obligately alkaliphilic H2-oxidising bacteria, suggesting that the enrichment of these bacteria may have occurred as a result of H2 generation during organic acid metabolism. The results from these experiments show that microorganisms are able to carry out a number of processes under highly alkaline conditions that could potentially impact on the properties of the host rock surrounding a geological disposal facility for intermediate level radioactive waste.

Long-term CO2 injection and its impact on near-surface soil microbiology.

Impacts of long-term CO2 exposure on environmental processes and microbial populations of near-surface soils are poorly understood. This near-surface long-term CO2 injection study demonstrated that soil microbiology and geochemistry is influenced more by seasonal parameters than elevated CO2 Soil samples were taken during a 3-year field experiment including sampling campaigns before, during and after 24 months of continuous CO2 injection. CO2 concentrations within CO2-injected plots increased up to 23% during the injection period. No CO2 impacts on geochemistry were detected over time. In addition, CO2-exposed samples did not show significant changes in microbial CO2 and CH4 turnover rates compared to reference samples. Likewise, no significant CO2-induced variations were detected for the abundance of Bacteria, Archaea (16S rDNA) and gene copy numbers of the mcrA gene, Crenarchaeota and amoA gene. The majority (75%-95%) of the bacterial sequences were assigned to five phyla: Firmicutes, Proteobacteria, Actinobacteria, Acidobacteria and Bacteroidetes The majority of the archaeal sequences (85%-100%) were assigned to the thaumarchaeotal cluster I.1b (soil group). Univariate and multivariate statistical as well as principal component analyses showed no significant CO2-induced variation. Instead, seasonal impacts especially temperature and precipitation were detected.

Mineralogical comparisons of experimental results investigating the biological impacts on rock transport processes.

This study investigates the influence of microbes on fluid transport in sedimentary and igneous host rock environments. It particularly focuses on granodiorite rock (Äspö; Sweden) and mudstone (Horonobe; Japan) that were utilised during laboratory-based column experiments. The results showed that biofilms form on both rock types in low nutrient conditions. Cryogenic scanning electron microscopy showed that the morphology of biofilaments varied from filamentous meshwork (in crushed granodiorite column experiments) to clusters of rod-like cells (fracture surfaces in mudstone). X-ray diffraction analysis of the fine fractions (<5 µm) revealed the formation of secondary clay mineral phases within the crushed Äspö granodiorite rock substrate only. The formation of secondary clay minerals appears to be enhanced when bacteria are present. All experiments showed biofilm formation, bacterial enhanced trapping of fines blocking off pore throats and/or secondary clay mineral formation. These observations illustrate the importance of bacteria on rock transport properties which will impact on the containment and migration of contaminants.