IAP-24-070

Nature-based solutions for coastal management – The role of biofilms in induced carbonate precipitation and sediment stability

Presently about 40% of the world’s population lives in coastal regions. Due to climate change, relative sea-level rise, reduced nearshore sediment supply from offshore and longshore sources and vulnerability to extreme storms are all expected to increase. As a result, coastal erosion is occurring at a faster rate than in the past with significant adverse environmental, economic and socio-cultural impacts. Coastal management and protection is essential to adapt to these changes and mitigate these impacts (Masselink et al. 2020; Perricone et al. 2023). This project aims to bring together expertise in carbonate geoscience, microbiology and coastal ecosystem management to develop innovative nature-based solutions for coastal management.

Sediment redistribution along coastlines is a natural process. Alongshore transport erodes sediment from one location to feed morphological units that can defend the shoreline elsewhere. An ample sediment supply, whether mud, silt, ands or gravel sized, is essential for the development of natural forms of coastal protections, such as saltmarshes, barriers, beaches and dunes. Sediment that is lost through longshore drift or erosion can be replenished, for example by local beach nourishment or so called “mega-nourishments” or “sandscaping” (Luijendijk et al. 2017) which contribute to a long-term positive sediment budget.

Currently, coastal geomorphological research is mainly morphodynamical, focussing on the mutual interactions between morphology, hydrodynamics and sediment transport. In this project we aim to better understand the role of bio-physical interactions on coastal processes and evolution, with regards to increasing sediment grainsize (ooid formation) and sediment stability (biofilms and cementation). Ooids are naturally occurring spherical sediment grains consisting of a core (nucleus) encapsulated by concentric layers of calcium carbonate (CaCO3) formed by microbial organomineralisation (Murray et al. 2017). Promoting nucleus formation through engineered biofilms could create a natural sediment supply in coastal systems while mineralising carbon. In addition, we will investigate the role of biofilms on the cohesiveness of existing sediment accumulations (e.g. alongshore barriers) and the possibility of enhancing carbonate mineralisation between sediment grains (cementation) to increase cohesiveness and reduce erosion of such coastal barrier systems.

Objectives:

Develop Biofilm-Enhanced Sediment Stability Techniques: Investigate and optimize the role of biofilms in promoting carbonate precipitation and sediment cohesiveness. Identify the environmental conditions and microbial interactions that enhance biofilm formation and possible cementation processes.

Create a Bio-Physical Model for Carbonate Precipitation: Construct a comprehensive bio-physical model that accurately describes the processes of biofilm-induced carbonate precipitation and sediment stabilization. This model will integrate findings from experimental studies at various scales and provide predictive capabilities for the effectiveness and scalability of biofilm-based coastal protection strategies.

The project will involve experimental work at a range of scales. Environmental parameters, such as nutrient availability, water chemistry and agitation, that promote biofilm and cementation (as ooid or intergranular cement)will be determined. Initial experiments will take place at microcosm scale, with the view to upscale this to mesocosm and small field scale studies where relevant. Utilising existing geochemical models and input from experimental work to develop a comprehensive bio-physical model that accurately describes the processes of biofilm-induced carbonate precipitation and sediment stabilization.

Year 1

Literature review, data identification and management, training in experimental design, microbiology and carbonate mineralisation processes. Selection of microbial organisms and pilot study.

Year 2

Microcosm and mesocosm experiments to determine the internal and external parameters that promote nucleus formation and associated carbonate precipitation within ooids. Dissemination of results at national conference.

Year 3

Microcosm and mesocosm experiments to determine the internal and external parameters that promote biofilm formation within sediments to promote cohesivity. Dissemination of results at international conference.

Year 3.5

Write up and completion of thesis. Journal manuscript preparation.

Newcastle University has a faculty run postgraduate research development programme that follows the Vitae Researcher Development Framework focusing on: knowledge and intellectual abilities, personal effectiveness, research governance and organisation, engagement, and influence and impact. Each PhD student has a tailor made Personal Development Plan, with the expectations of them to take 60 credits in the first year and 40 credits in the second year.

The student will be part of the geosciences research group at Newcastle and the large Modelling, Evidence and Policy research group, working alongside other researchers across a range of natural sciences projects and have the opportunity to be involved with Newcastle University’s Centre for Climate and Environmental Resilience.

The student will be part of the IAPETUS DTP which offers a multidisciplinary package of training focused around meeting the specific needs and requirements of each student, benefitting from the combined strength and expertise that is available across the partner organisations.