CalcUlating the strength of the Plastic pump In counteracting the Deep export of Oceanic carbon (CUPIDO)

The amount of plastic entering our oceans is increasing (8 million tonnes p.a.) with global implications for the health of our planet. As this plastic debris degrades in the ocean, fragmentation will shift particle size from large plastics to smaller microplastics, even in the absence of any new inputs. Thus, the problem of microplastic pollution will only increase in future years. However, the ways in which microplastics are transported to the deep ocean are still largely unknown. This limits our ability to determine the impacts of plastic debris on the ocean ecosystem and how these can be alleviated.
Microplastic debris interact with dynamic communities of zooplankton. These small organisms, which are at the base of marine food chains, ingest microplastics and repackage them into faecal pellets which may become deposited deep in the ocean over the cycle of diel vertical migration. Microplastics may also become incorporated into zooplankton body tissue which, at the end of life, will sink as part of the carcass.
I am introducing a new concept of the "Plastic Pump", to collectively describe the process of incorporation of plastics into biological processes and their subsequent movement to depth. The Plastic Pump may interacts with the biological capability of the ocean to export carbon from the surface to depth (a process known as Biological Carbon Pump, BCP). Further elucidation of the interaction between the Plastic Pump and the BCP is important since the BCP provides a critical ecosystem service in mitigating climate change through uptaking and storing anthropogenically-derived atmospheric CO2 in the deep ocean. Interference by the Plastic Pump may reduce the effectiveness of the BCP. This has yet to be determined.
CUPIDO will undertake two cruise expeditions where a suite of cutting edge approaches, at the intersection of biogeochemistry, material science, and biology, will be used. These approaches include floating and moored platforms that will not only determine depth profiles of plastic concentrations over seasons, but also how plastics interact with the natural ecosystem over these depths. It will also deploy a unique device, built in-house to my own design and specifications, to evaluate how oceanic plastics alter over long time scales through incubating pre-selected meso- and microplastics in in situ conditions.
CUPIDO will focus on two regions located in the Southern Ocean (SO) and the Mediterranean Sea (MS). The contrasting conditions of the two selected regions (relatively pristine vs. highly polluted) allow for a comparative analysis of the impact of the Plastic Pump on the ocean's ability to export and sequester C within a low (SO) and high (MS) plastic input regime.
My CUPIDO team will measure how the characteristics of plastics alter as a function of exposure to the marine environment; the vertical distribution and export of plastic over daily and seasonal timescales, and the role of zooplankton as vectors of plastics through the water column. This wealth of novel data will be analysed and modelled to predict: (i) the accumulation of plastics in specific water layers through the water column and (ii) how the flux of plastics and C alters over an annual cycle in regions of high and low plastic debris input.
Overall, CUPIDO will address the hypothesis that zooplankton and food web associated processes play a major role in promoting the sinking of plastic through the water column. These mechanisms will decrease the ability of the marine ecosystem to transfer C from the surface to the deep ocean (resulting in a slowing of the BCP). The service provided by the BCP in lowering atmospheric CO2 levels has an economic significance to the mitigation of climate change. Through parameterising the various components of the Plastic Pump, CUPIDO will assess the economic impact of microplastic debris on the BCP and the value of combatting marine plastic pollution to restore levels of climate change mitigation.

Scientific community: CUPIDO aims to provide the scientific community with a new perspective of the impact of plastic debris, with regards its interaction with the processes of ocean carbon (C) flux and sequestration. This will represent a step-change in our understanding of the influence of plastic on climate change, which has relevance to a wide range of scientific communities. Chemical, biological, physical oceanographers and environmental engineers will benefit from a greater understanding of the role that plastic marine debris plays in C export. The biogeochemical cycle modelling community will benefit from the data generated by this project to improve model parameterisation, particularly with regards the interaction between microplastics and the Biological Carbon Pump.

Policy Community: The impact of plastic on the ability of the ocean to export C is of relevance for the United Nations Framework Convention on Climate Change and links with the UN Sustainable Development Goal, SDG14 'life below water'. CUPIDO outcomes will help organizations such as the United Nation Environmental Program-UNEP and Commission for the Conservation of Antarctic Marine Living Resources-CCAMLR (which have a target framework on marine litter), to develop environmental management and targeted action. I will work closely with members of these organizations to facilitate actions. CUPIDO will provide an additional mechanistic understanding of C uptake processes which will feed into the Intergovernmental Panel for Climate Change-IPCC and will help to inform policy makers in implementing the Marine Strategy Framework Directive.
The work I will lead will inspire the Global Economy in UK to shape the direction of future policy on plastics. Especially, it will link with the 'Blue Economy', an emerging concept which encourages a stewardship of oceanic 'blue' resources (Commonwealth Blue Charter) highlighting linkages between the ocean, climate change, and the wellbeing of people. Environmental economists will be able to use CUPIDO outputs to assess the economic cost of lost climate mitigation due to the impact of ocean microplastics on C export.

Commercial Sector: I will active in interacting with the industrial sector by providing a test-bed platform to trial new devices that can investigate the quantity and nature of plastic in the ocean. This approach will generate interest in the Global plastics industry (officially united under a Global Declaration with 70 signatories in 40 countries) which has committed to "work with the scientific community and researchers to better understand and evaluate the scope, origins and impact of marine litter". The established interaction with the project partner Chelsea Technologies Group is one example.

General Public: A large portion of the general public has a keen interest in environmental science, especially in how we can minimise our impact on the environment. 50% of plastic debris is from single-use packaging and reducing its use is an achievable target that the general public can engage with. CUPIDO science will raise public awareness of how plastic pollution impacts ocean services and the common social benefit they provide. I aim to inspire the next generation of marine environmental scientists by participating in school science talks. The CUPIDO team will also write features for the NERC Planet Earth Magazine and conduct an interactive blog on its project website. CUPIDO will disseminate the project through multiple public engagement routes, such as Cambridge and Genoa Science festivals and Science open days at BAS and other platforms (e.g. Pint of Science, University of the Third Age-U3A) as well as the UK National Environmental Educators. CUPIDO will also participate in events at the Natural History Museum, Science Museum and other regional museums to enhance outreach.