Anita successfully defended her thesis on Jan 13, 2015.

Title of Ph.D. thesis:

"Carbon Pumps in the Benguela Current Upwelling System"

Congratulations!

Supervising tutors:

Dr. T. Rixen                                                                                             
Prof. Dr. K.-C. Emeis

Biogeochemistry                                                                                     

Leibniz Center for Marine Tropical Ecology, Bremen
University of Hamburg, Institute of Geology

Outline sub-project 4:

Although coastal upwelling zones make up less than 0.5% of the world ocean area, they account for a disproportionate amount of global new production and fish catch and play a significant role in the oceanic carbon budget. The inorganic carbonate system as well as air–sea CO₂ fluxes in coastal environments are influenced by a range of processes, including enhanced biological productivity, upwelling and organic and inorganic inputs from rivers. Although there has been an increasing interest in ocean carbon cycling since the issue of Climate Change emerged, coastal regions are rarely represented due to the high variability in biogeochemical conditions. Nevertheless especially upwelling regions are valuable systems to study the physical versus biological pump and their effect on the carbonate system.

The Benguela Current (BC) is one of the 4 major eastern boundary upwelling systems. A combination of shelf width and coastal topography in connection with southerly wind stress creates a number of discrete upwelling cells. The Lüderitz upwelling cell at 27°S is thought to establish an environmental perennial barrier, separating the upwelling region in two subsystems. This is thought to affect the biological distribution but also the chemical composition of these regions.

My research is focused on the biogeochemical characteristics with emphasis on the carbon cycle, its linkages to oxygen depletion and H₂S events and aims to provide essential background information for studies conducted on biota as well as on matter and energy flows within the GENUS Project.

The main scientific objectives of my doctoral thesis are to investigate:

• the variability of vertical patterns of δ¹³C DIC, pCO₂, Alkalinity and DIC during upwelling along the  west coast of Africa (cross shelf transects).

• diurnal dynamics of nutrients, oxygen and hydrogen sulfide in surface water during upwelling and their relation to changes in Alkalinity and DIC in collaboration with the National Marine Information & Research Centre (NatMIRC), Swakopmund, Namibia.

• the export flux of organic matter by analysis of sediment trap data.

The results will contribute to a better understanding of the BC´s spatial and temporal heterogeneity in terms of its biogeochemical features and thus help to estimate its role in carbon sequestration.