UKCCSC Theme C – CCS and the Environment

Theme Leader: Carol Turley, Plymouth Marine Laboratories

• C1 – Marine Ecosystem models. Leader Jerry Blackford, Plymouth Marine Laboratories
• C2 – Laboratory Mesocosms. Leaders Steve Widdicome & Andy Rees, Plymouth Marine Laboratories
• C3 – Natural analogues. Leader Carol Turley, Plymouth Marine Laboratories
• C4 – Scientific Literature. Leaders Carol Turley, Plymouth Marine Laboratories; Jeremy Colls, University of Nottingham
• C5 – Field experiments. Leader Jeremy Colls, University of Nottingham
• C6 – Socio-economics. Leader Mel Austen, Plymouth Marine Laboratories; Carol Turley, Plymouth Marine Laboratories
• C7 – Networking. Leader Carol Turley, Plymouth Marine Laboratories

The aim is to investigate the potential impacts of CO₂ leakage during capture and storage and compare these to the environmental impacts of non-intervention. It is established that CO₂ contamination of the marine system, either by uptake from the atmosphere or through leakage of stored CO₂, will impact the ecosystem by reduction of pH (increasing acidification) (Turley 2004 and refs within). The marine environment is particularly sensitive: acidification disrupts the formation of calcareous structures by many of the key organisms and alters the form and availability of nutrients. In shelf sea environments both the sediment and water biogeochemistry play a crucial role in maintaining the productivity and balance of the whole ecosystem. Sediments are also a repository of contaminants. A change in sediment pH may result in pollutant remobilisation, thereby adding a further stress on the biota. Similarly on land, potentially sensitive areas may be above underground storage facilities or around transport pipelines, where toxic effects of leakage may be significant. Evidently, in order to protect and manage the environment effectively it is vital that the impact of CO₂ contamination on the health and functioning of sediment, water and soil ecosystems is understood.

Approach

We will focus on the environmental issues surrounding CO₂ underground storage and assess the effects of chronic or catastrophic release on marine and land-based ecosystems. The marine component will be achieved through a programme of work that will evaluate the physical, geological, chemical and biological changes under different CO₂concentrations using ecosystem models, controlled experimental laboratory mesocosms, natural analogues and the scientific literature. Terrestrial plant responses to elevated soil CO₂ will be investigated through intensive field-scale experiments using common agricultural species. A strong emphasis will be placed on making robust scientific data readily available in practical formats to social and economic scientists within the consortium.

To assess the relationship between pH and nutrient cycling in the marine environment, intact replicate cores will be taken from a number of different sediment types and subjected to a range of pH treatments. Nutrients flux rates and sediment concentrations will be measured. Experiments will be repeated three times throughout the year to assess the effects of seasonal variability on any relationship between nutrient cycling and pH. To determine the relationship between pH and contaminant remobilisation, sediment cores, naturally contaminated by a variety of organic or inorganic pollutants, will be collected. These sediment cores will be subjected to a range of pH treatments and the impact on contaminant flux rates and sediment concentrations will be measured. Additionally, for each of the above experiments, the impact on key organisms present within the cores will be assessed using established ecotoxicological techniques.

Using the data generated from the above experiments, in addition to existing data, we will develop existing coupled benthic–pelagic models of the UK continental shelf to quantify the impact of acidification on benthic biota and sediment characteristics. The model will be extended to represent key species and key pollutants. Results from scenario testing with the model will underpin socio-economic impact assessments.

To investigate plant responses, tanks of soil will be gassed at the base with CO₂, resulting in a uniform upward vertical flux of gas, simulating an escape from an underground pipeline or deep terrestrial storage zone. Plant responses and concentrations of CO₂ and O₂ in the soil will be measured, and carbon isotope ratios used to discriminate injected gas. Soil samples will also be analysed for changes in biotic and chemical characteristics. The outputs from these experiments will tell us what damage a leak from CO₂ infrastructure (or storage) might cause to surface vegetation, and indicate plant responses that could act as early warning signs of such a leak.