Carbon Capture and Storage (CCS) is a crucial technology to enable the decarbonisation of fossil fuel electricity generation. The UK has considerable potential for geological storage of CO2 under the North Sea and extensive offshore industry experience that could be applied. While initial storage is likely to be undertaken in depleted oil and gas fields, much larger saline aquifer formations are estimated to have sufficient capacity to securely contain 100 years of current UK fossil fuel power plant CO2 emissions. The CO2 Aquifer Storage Site Evaluation and Monitoring (CASSEM) project brings together the experience and different working practices of utilities, offshore operators, engineering contractors, and academic researchers to build collective understanding and develop expertise. CASSEM produced both new scientific knowledge and detailed insight into the CCS industry, developing best-value methods for the evaluation of saline aquifer formations for CO2 storage. Alongside work to assess the storage potential of two saline aquifer formations in close proximity to large coal power plant, CASSEM applied a novel Features, Events and Processes method to explore perceptions of risk in the work undertaken. This identified areas of industry and research community uncertainty and unfamiliarity to enable targeted investment of resource to reduce overall project risk. An openly accessible and flexible full chain (CO2 capture, transport and storage) costing model was developed allowing the CCS community to assess and explore overall costs. CASSEM's work also included the first use of citizen panels in the regions investigated for storage to assess public perception and educate the general public about CCS.

The response of the benthic microbial community to a controlled sub-seabed CO2 leak was assessed using quantitative PCR measurements of benthic bacterial, archaeal and cyanobacteria/chloroplast 16S rRNA genes. Similarly, the impact of CO2 release on the abundance of benthic bacterial and archaeal ammonia amoA genes and transcripts, and also to the abundance of nitrite oxidizer (nirS) and anammox hydrazine oxidoreductase (hzo) genes and transcripts. Samples were taken from four zones (epicentre (zone 1); 25m distant (zone 2), 75m distant (zone 3) and 450m distant (zone 4)) during 6 time points (7 days before CO2 exposure, after 14 and 36 days of CO2 release, and 6, 20 and 90 days after the CO2 release had ended). Changes to the active community of microphytobenthos and bacteria were also assessed before, during and after CO2 release using Denaturing Gradient Gel Electrophoresis of cyanobacteria/chloroplast 16S rRNA. Changes to the composition of the active bacterial community was assessed first using Terminal Restriction Fragment Length Polymorphism (T-RFLP) of bacterial 16S rRNA. In depth comparisons of possible changes to the active bacterial community at zone 1 and 4 before, during and immediately after the CO2 release was performed using 16S rRNA 454 pyrosequencing. This dataset was created by Plymouth Marine Laboratory (PML) under the program QICS (Quantifying and monitoring environmental impacts of geological carbon storage) which was funded by the Natural Environment Research Council (NERC), with support from the Scottish Government. The results are contained in three text files. QICS project website: www.bgs.ac.uk/qics/home.html. Tait et al. (2015) Rapid response of the active microbial community to CO2 exposure from a controlled sub-seabed CO2 leak in Ardmucknish Bay (Oban, Scotland). IJGGC DOI: 10.1016/ijggc.2014.11.021. Watanabe et al. (2015) Ammonia oxidation activity of microorganisms in surface sediment to a controlled sub-seabed release of CO2. IJGGC DOI: 10.1016/j.ijggc.2014.11.013.

The potential for leakage of CO2 from a storage reservoir into the overlying marine sediments and into the water column and the impacts on benthic ecosystems are major challenges The potential for leakage of CO2 from a storage reservoir into the overlying marine sediments and into the water column and the impacts on benthic ecosystems are major challenges associated with Carbon Capture and Storage (CCS) in subseafloor reservoirs. To investigate the consequences of CO2 leakage for the marine environment, a field-scale controlled CO2 release experiment was conducted in shallow, unconsolidated marine sediments. Changes of the chemical composition of the sediments, their pore waters and overlying water column were monitored before, during and up to 1 year after the 37-day long CO2 release from May 2012 to May 2013. In particular this focused on changes in the solid phase (physical properties, major and minor elemental composition, inorganic and organic carbon content), the pore water chemical composition (cations, anions, nutrients and the carbonate system parameters total alkalinity, dissolved inorganic carbon and isotopic signature of DIC) and the water column chemical composition (oxygen, nutrients, total alkalinity and dissolved inorganic carbon). This dataset was collected by the National Oceanography Centre (NOC) under the program QICS (Quantifying and monitoring environmental impacts of geological carbon storage) which was funded by the Natural Environment Research Council (NERC), with support from the Scottish Government. The results are contained in an Excel file. QICS project website: www.bgs.ac.uk/qics/home.html. Lichtschlag et al. (2014) Effect of a controlled sub-seabed release of CO2 on the biogeochemistry of shallow marine sediments, their pore waters, and the overlying water column, http://www.sciencedirect.com/science/article/pii/S1750583614003090 (doi:10.1016/j.ijggc.2014.10.008).

Our proposed research is based on cores collected during the recent, and very successful, Integrated Ocean Drilling Program (IODP) Expedition 340. The aims of this expedition were to investigate the volcanism and landslide history of the Lesser Antilles volcanic arc, by collecting a number of cores offshore Montserrat and Martinique. As a shipboard planktic foraminifera (single celled calcareous plankton) biostratigrapher (dating sediment cores using the appearances and disappearances of fossil plankton), Deborah Wall-Palmer (proposed PDRA) has access to these cores during the one year moratorium period. Until IODP Exp. 340, the longest continuous record (~250,000 years) of volcanic activity on Montserrat was a 5.75 m core collected to the south-west of the island in 2002, CAR-MON 2. This core revealed a more extensive and complete record of volcanic activity than that available in terrestrial cores. The longest continuous sediment record collected during Exp. 340 extends this record considerably. At 139.4 m in length, Hole U1396C records events back to 4.5 million years ago. The majority of this Hole will undergo stratigraphic analysis at low resolution, which will be carried out by other Exp. 340 scientists (Andrew Fraass, Mohammed Aljahdali). The upper 7 m section of this Hole is estimated to span 300,000 years and is comparable to the time period recovered in sediments for Holes U1394A/B (0 to 125 cm) and U1395B (0 to 30 cm). Holes U1394A/B and U1395B were collected close to Montserrat, in the main path of eruptive material from the Soufriere Hills volcano and contain a high resolution, but interrupted record of volcanic eruptions and landslides. Our proposed research is to provide a high resolution (every 2000 yrs) age framework across the upper ~300,000 year sections of these three cores. This will be achieved by collecting specimens of the planktic foraminifera Globigerinoides ruber and analysing the stable oxygen isotope ratios contained within their calcium carbonate tests (shells). Oxygen isotope ratios provide information about the global ice volume and global climate, and the standard record can be identified world-wide. Correlation to this record can therefore be used to provide an age framework for sediments, which is more detailed than using the biostratigraphic range of species alone. Producing this age framework is essential for achieving the overall aims of Exp. 340 as it will be used, in collaboration with several other Exp. 340 scientists, to reconstruct the volcanic and landslide history of Montserrat. In addition to this, to ensure the conservative use of samples, some further work will be carried out on samples requested from the upper 7 m of Hole U1396C. This will assist in constructing the low resolution stable isotope and biostratigraphic framework for the remainder of this Hole. The majority of this work is being carried out by Andrew Fraass (University of Massachusetts) and Mohammed Aljahdali (Florida State University). We will analyse the upper 7 m of Hole U1396C, at low resolution, for stable oxygen isotopes of the benthic foraminifera Cibicidoides spp. and for planktic foraminifera datum species.

The potential for leakage of CO2 from a storage reservoir into the overlying marine sediments and into the water column and the impacts on benthic ecosystems are major challenges associated with Carbon Capture and Storage (CCS) in subseafloor reservoirs. A field-scale controlled CO2 release experiment was conducted in shallow, unconsolidated marine sediments. Changes were monitored of the chemical composition of the sediments and overlying water column before, during and up to 1 year after the 37-day long CO2 release from May 2012 to May 2013 in Ardmucknish Bay. Meiofaunal samples were collected and meiofauna higher taxa and the nematodes species (where possible) were identified by Plymouth Marine Laboratory. This dataset was collected under the program QICS (Quantifying and monitoring environmental impacts of geological carbon storage) which was funded by the Natural Environment Research Council (NERC), with support from the Scottish Government. The results are contained in an Excel file. QICS project website: www.bgs.ac.uk/qics/home.html. This data is currently under embargo until publication of the dataset in research article (estimated end of 2015).

Subsurface 3D geological models of aquifer and seal rock systems from two contrasting analogue sites have been created as the first step in an investigation into methodologies for geological storage of carbon dioxide in saline aquifers. Development of the models illustrates the utility of an integrated approach using digital techniques and expert geological knowledge to further geological understanding. The models visualize a faulted, gently dipping Permo-Triassic succession in Lincolnshire and a complex faulted and folded Devono-Carboniferous succession in eastern Scotland. The Permo-Triassic is present in the Lincolnshire model to depths of -2 km OD, and includes the aquifers of the Sherwood Sandstone and Rotliegendes groups. Model-derived thickness maps test and refine Permian palaeogeography, such as the location of a carbonate reef and its associated seaward slope, and the identification of aeolian dunes. Analysis of borehole core samples established average 2D porosity values for the Rotliegendes (16%) and Sherwood Sandstone (20%) groups, and the Zechstein (5%) and Mercia Mudstone (<10%) groups, which are favourable for aquifer and seal units respectively. Core sample analysis has revealed a complex but wellunderstood diagenetic history. Re-interpretation of newly reprocessed seismic data in eastern Scotland has significantly reduced interpretative uncertainty of aquifer and seal units at depths of up to -6 km OD in a complex faulted and folded Devonian-Carboniferous succession. Synthesis of diverse data in the 3D geological model defines a set of growth folds and faults indicative of active Visean to Westphalian dextral-strike slip, with no major changes in structural style throughout the Carboniferous, in contrast to some published tectonic models. Average 2D porosity values are 14-17% in aquifer units and <2% in the seal unit, with a ferroan dolomite cement occluding porosity at depth.

Carbon Capture and Storage (CCS) is a crucial technology to enable the decarbonisation of fossil fuel electricity generation. The UK has considerable potential for geological storage of CO2 under the North Sea and extensive offshore industry experience that could be applied. While initial storage is likely to be undertaken in depleted oil and gas fields, much larger saline aquifer formations are estimated to have sufficient capacity to securely contain 100 years of current UK fossil fuel power plant CO2 emissions. The CO2 Aquifer Storage Site Evaluation and Monitoring (CASSEM) project brings together the experience and different working practices of utilities, offshore operators, engineering contractors, and academic researchers to build collective understanding and develop expertise. CASSEM produced both new scientific knowledge and detailed insight into the CCS industry, developing best-value methods for the evaluation of saline aquifer formations for CO2 storage. Alongside work to assess the storage potential of two saline aquifer formations in close proximity to large coal power plant, CASSEM applied a novel Features, Events and Processes method to explore perceptions of risk in the work undertaken. This identified areas of industry and research community uncertainty and unfamiliarity to enable targeted investment of resource to reduce overall project risk. An openly accessible and flexible full chain (CO2 capture, transport and storage) costing model was developed allowing the CCS community to assess and explore overall costs. CASSEM's work also included the first use of citizen panels in the regions investigated for storage to assess public perception and educate the general public about CCS. CASSEM now plans to apply and further develop the methodologies established to test the viability of using a large offshore saline aquifer to store CO2 from multiple sources, leading to the proving of such a store by test injection of CO2.

QICS (Quantifying and monitoring environmental impacts of geological carbon storage) was a program funded by the Natural Environment Research Council (NERC), with support from the Scottish Government (May 2010 - December 2014) with two objectives. Firstly, to assess if any significant environmental impact would arise, if a leak from sub-sea, deep geological storage of carbon dioxide occurred. Secondly, to test and recommend tools and strategies for monitoring for (or assuring the absence of) leakage at the sea floor and in overlying waters. This data set provides a short overview of the novel experimental procedure - a world first leakage simulation in the natural environment and describes the experimental set up, sampling strategy including both temporal and spatial details. The data set consists of a pdf containing a text based project and experimental overview, a table outlining the temporal evolution of the experiment, including site selection, set up, baseline, impact and recovery phases and a diagram outlining the spatial sampling strategy. This data set contains an overview document collated by Plymouth Marine Laboratory. This provides the context for a number of specific related QICS datasets submitted to the UKCCS data archive, covering a range of geological, chemical and ecological information. QICS project website: www.bgs.ac.uk/qics/home.html. Blackford et al., 2014. Detection and impacts of leakage from sub-seafloor deep geological carbon dioxide storage. Nature Climate Change 4, 1011-1016. DOI: 10.1038/NCLIMATE2381. Taylor et al., 2015. A novel sub-seabed CO2 release experiment informing monitoring and impact assessment for geological carbon storage. Int J Greenhouse Gas Control. DOI:10.1016/j.ijggc.2014.09.007.

The CASSEM project developed new methodologies, workflows and insights essential for the successful identification and evaluation of safe and effective CO2 storage sites in offshore saline aquifers. The project selected on-shore and/or near-shore sites from which useful analogue data and information was obtained in order to characterise important aquifer and cap rock systems. Such onshore data acquisition enables key information to be gathered (through outcrop and/or borehole sampling) at much lower cost than could be achieved for long-term offshore storage options.

The QICS project (Quantifying and Monitoring Potential Ecosystem Impacts of Geological Carbons Storage) was established to improve our understanding of the potential impacts of CO2 release on the environment and to develop tools and best practice for monitoring sub-seabed CCS reservoirs. To monitor the potential impact of a CO2 leak to surficial benthic megafauna, cages of bivalves (the common mussel Mytilus edulis Linnaeus, 1758 and the king scallop Pecten maximus (Linnaeus, 1758)) were deployed at the gas release site and at a reference site in the QICS experiment - both within Ardmucknish Bay, Oban, Scotland. Replicate individuals were sampled at six time points over a 125-day period, which spanned both the 37-day injection and recovery phases of the experiment, in order to establish impacts to molecular physiology. Samples of bivalves were also simultaneously sampled from a reference site within the bay in order to contrast changes in physiology induced by the gas release with naturally variability in the physiological performance of both species. There was no evidence of gene regulation of either selected carbonic anhydrases (CAx genes) or the alpha subunit of sodium potassium ATPAses (ATP1A genes) in individual bivalves collected from the CO2 gas release site, in either species. In the common mussel Mytilus edulis there was only evidence for changes with time in the expression of genes coding for different classes of carbonic anhydrase. It was concluded that the effects of the plume of elevated pCO2 on ion-regulatory gene transcription were negligible in both species. Pratt et al. 2015. No evidence for impacts to the molecular ecophysiology of ion or CO2 regulation in tissues of selected surface-dwelling bivalves in the vicinity of a sub-seabed CO2 release. International Journal of Greenhouse Gas Control. DOI:10.1016/j.ijggc.2014.10.001. QICS project website: www.bgs.ac.uk/qics/home.html.