Seasonal inorganic carbon dynamics at the land-ocean interface

The 2015 Paris agreement, which the UK has ratified, commits countries to keep global warming below 2 degrees Celsius by limiting greenhouse gas emissions. The oceans take up about a quarter of the carbon dioxide (CO2) emissions by human activity. However, oceanic outgassing of carbon transported by rivers from the land to the oceans is a major uncertainty in estimates of the oceanic CO2 uptake, such as used in the Global Carbon Budget (http://www.globalcarbonproject.org/). This PhD studentship has the objective to reduce this uncertainty by determining how organic carbon degradation in UK estuaries increases CO2 release in these estuaries and shelf seas. The project is ofdirect relevance for management of blue carbon, the carbon stored in coastal and marine ecosystems in the form of biomass and carbon-rich sediments. The project links to the UK programme on Land Ocean Carbon Transfer (LOCATE, http://locate.ac.uk/), in which samples are taken along the salinity gradient in 20 UK estuaries at different times of the year. The project will supplement the LOCATE programme with the analysis of carbonate chemistry parameters. This will allow study of the breakdown oforganic carbon to inorganic carbon in the estuaries and the resulting outgassing of CO2 to the atmosphere. In addition, the student will undertake year-round sampling for carbonate chemistry parameters at two Cefas Smart Buoy sites (https://www.cefas.co.uk/cefas-data-hub/smartbuoys/) in UK coastal waters and participate in a North Sea-wide cruise. The student will combine the new data with existing data sets for the Smart Buoys and the North Sea. Study of these estuarine and North Sea carbon data will provide an insight into how organic matter degradation increases the inorganic carbon load and carbon transfer at the land-ocean interface. The research will enable quantification of oceanic outgassing of riverine carbon for the UK and will aid better valuation and management of blue carbon, thus addressing key knowledge gaps relevant for the Paris agreement. The project will be jointly hosted by Cefas, a UK government marine research agency, the National Oceanography Centre (NOC) and the University of East Anglia (UEA). The supervisors are marine biogeochemists with expertise in land-ocean carbon transfer, ocean observations, ocean carbon cycling and uptake, blue carbon and translating science into policy relevant information.