About This Project

Microplastics are accumulating in the sea surface microlayer (the uppermost millimeter of the ocean surface that is in direct contact with the atmosphere). What this means for ocean-atmosphere gas exchange, including for CO2, is uncertain. We know that these microplastics are encouraging the production of biological surfactants when they interact with ocean biology, and that surfactants reduce gas exchange. I aim to estimate this effect globally using observational data.

Ask the Scientists

What is the context of this research?

The properties of the ocean's surface microlayer, it's "skin", control the air-sea exchange of gases including CO2. Biological surfactants are produced naturally by phytoplankton and bacteria, and they accumulate in this microlayer, where they can reduce gas transfer. Globally the effect of these surfactants on inhibiting air-sea CO2 exchange may be significant, but few have studied the matter carefully. Recently it has been shown that microplastics can stimulate the production of biological surfactants. This is a concern because the ocean's microlayer is a growing repository for microplastics. To fight climate change, we need to keep the ocean taking up as much CO2 from the atmosphere as possible. At present the current and future risks to this uptake from microplastics are unknown. Fortunately, new observational datasets can be used to make a first estimate of the risk of microplastic-stimulated surfactants to ocean CO2 uptake.

What is the significance of this project?

The world needs effective responses to both climate change and microplastic pollution. In order to respond effectively we need to understand the current and future threats both pose to the overall functioning of the Earth system. This research will provide a first estimate of the threat of microplastics in the ocean's "skin" to the long-term functioning of the ocean's CO2 uptake from the atmosphere. This information is incredibly important to have for both the climate change science and policy communities as well as for the plastic pollution science and policy communities. Right now a Global Plastics Treaty is being negotiated to regulate plastics' full life cycle, presenting a golden opportunity to design a legal instrument that can effectively address both microplastics pollution and climate change. Project outcomes can help to inform these Treaty discussions as well as the work of the Intergovernmental Panel on Climate Change.

What are the goals of the project?

The project will estimate the impact of microplastics on contemporary surfactant production and suppression of air-sea CO2 exchange, using a combination of observational data for physical, chemical, and biological variables and model output for ocean surface microplastic concentrations. These datasets provide a time-series of information that can be used to estimate global air-sea CO2 exchange over recent decades, and experimental data can be used to estimate the role of microplastics in regulating this exchange. The work can start immediately when funded. Step 1: build a global time-series of air-sea CO2 fluxes using standard methods (that do not consider surfactant suppression). Step 2: recalculate the air-sea CO2 flux time-series using a surfactant suppression factor to estimate the impact of surfactants. Step 3: estimate what portion of the surfactant CO2 flux suppression is due to microplastics based on microplastics concentrations.