Microplastics and carbon sequestration: identifying links and impacts

Dr Sue Hartman, Dr Katsiaryna PabortsavaDr Peter Brown, Dr Phyllis Lam, Ms Stefanie Rynders
Rationale: 

The downward sinking flux of marine organic particles (e.g. as marine snow and faecal pellets) removes large amounts of carbon dioxide from the atmosphere to the deep ocean where it is stored for centuries – a process known as the biological carbon pump (BCP). Amongst physical and biogeochemical processes that control the magnitude of the BCP, the interaction of sinking material with small plastic debris (microplastics) could potentially alter the quantity of carbon delivered to the abyss. At the same time, microbial growth on the surfaces of microplastics as well as their attachment to and entrainment into sinking material facilitates the transfer of these contaminants to depth and prevents their accumulation in the surface ocean. The interactions between microplastics and marine organic matter have been shown in the laboratory but is yet to be studied in situ. This project proposes a combination of direct observations resolved in both time and space, and in relation to environmental forcing (e.g. productivity, circulation patterns, atmospheric processes, etc.) which will allow for a better understanding of the nature and impacts of these interactions on the global carbon cycle and risks associated with plastic pollution. 

Methodology: 

The student will quantify and characterize the amount of particulate organic carbon, (bio)minerals, and microplastics contained in the deep (3000 m) sediment trap material collected continuously at Porcupine Abyssal Plain (PAP) and the Northern and Southern Atlantic Oligotrophic gyres for the past decade. They will use ancillary data from in situ and remote sensors and field measurements to assess spatio-temporal changes in the magnitude and composition of particle flux in a context of different environmental factors. They will investigate the impact of microplastics on quality of material arriving to the abyss by comparing sinking speeds, carbon and amino acid content of zooplankton faecal pellets found in the traps to the amount of microplastics incorporated in them. The student will participate in a research expedition to PAP site to collect fresh marine particles for microbial colonization and aggregation studies with microplastics. They will use eddy-resolving 1/12 NEMO model simulations with off-line particle tracking to investigate the changes in the particle spread to the different ocean dynamical mechanisms and identify regional accumulation hot-spots. The results will be combined with the existing and newly acquired observational and experimental data to establish potential links between advective and downward fluxes of natural particles and microplastics to depth and their respective impacts.

 

Location: 
NOC Southampton
Training: 

The INSPIRE DTP programme provides comprehensive personal and professional development training alongside extensive opportunities for students to expand their multi-disciplinary outlook through interactions with a wide network of academic, research and industrial/policy partners.

The student will be registered at the University of Southampton and hosted at the National Oceanography Centre, in the Ocean BioGeosciences Research Group. The research group is renowned globally as one of the leading centres of excellence in biological carbon research with particle flux biogeochemists, plankton ecologists, marine geochemicsts, deep-sea biologists, numerical modellers, and remote sensing specialists working together to address the most significant problems in oceanography. Recently, the group expanded its expertise towards anthropogenic impacts on aquatic and marine ecosystems, including microplastic contamination. The student will learn the skills for field sampling and experimental design, microscopy, elemental analysis (mass- and atomic-emission spectrometry, thermal conductivity detection), molecular-ecological techniques, and spectroscopic imaging analysis and processing for plastic detection and characterisation. Other training will include statistical analysis and handing high-resolution modelling output, along with the Lagrangian tracking techniques.

 

Eligibility & Funding Details: 

Please check https://inspire-dtp.ac.uk/how-apply for details.  

 

Background Reading: 

Pabortsava, K., Lampitt, R.S. High concentrations of plastic hidden beneath the surface of the Atlantic Ocean. Nat Commun 11, 4073 (2020). https://doi.org/10.1038/s41467-020-17932-9

 

Pabortsava, Katsiaryna; Lampitt, Richard; Benson, Jeff; Crowe, Chris; McLachlan, Robert; Le Moigne, Frederic A.C.; Moore, C. Mark; Pebody, Corinne; Provost, Paul; Rees, Andrew; Tilstone, Gavin; Woodword, E. Malcolm. 2017 Carbon sequestration in the deep Atlantic enhanced by Saharan dust. Nature Geoscience, 10 (3). 189-194.https://doi.org/10.1038/ngeo2899

 

Hartman, S.E., Z.-P. Jiang, D. Turk, R.S. Lampitt, H. Frigstad, C. Ostle and U. Schuster (2015) Biogeochemical variations at the Porcupine Abyssal Plain sustained Observatory in the northeast Atlantic Ocean, from weekly to inter-annual timescales. Biogeosciences 12(3):845–853 (http://doi.org/10.5194/bg-12-845-2015)

 

Kelly, S., Popova, E., Aksenov, Y., Marsh, R. and Yool, A., (2018). Lagrangian modeling of Arctic Ocean circulation pathways: Impact of advection on spread of pollutants. Journal of Geophysical Research: Oceans, 123(4), pp.2882-2902.

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