TANGAGAS

TANGAGAS (Greenhouse Gas fluxes in Lake Tanganyika) is a FRS-FNRS funded project (CR, 2019-2020).

Inland waters (streams, rivers, lakes and reservoirs) are important players in the global budgets of long-lived green-house gases (GHGs), acting as vigorous sources to the atmosphere of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). Available data suggest that CH4 emissions from inland waters are highest at tropical latitudes although these are also the regions where data are dramatically scarce and urgently needed to improve accuracy of emission estimates. On the other hand available data suggest that tropical lakes are not as intense CO2 emitters as their temperate and boreal counterparts, and that in fact they could sinks for atmospheric CO2.

The main goal of the TANGAGAS project is to fill an enormous data gap by acquiring a seasonally and spatially resolved data-set of CO2, CH4 and N2O dissolved concentrations in Lake Tanganyika, one of the largest and deepest lake in the tropics and in the World, where to our best knowledge no data are available on the dissolved concentration of these GHGs. The data-set will allow to compute the GHG fluxes with the atmosphere, and the analysis with ancillary data (O2, nutrients, phytoplankton pigments, organic matter concentration and stable isotopic composition) will also allow to decipher the biogeochemical processes that control the temporal variability and the spatial distribution of these GHGs.

We will use recently acquired laser spectroscopy instrument for CO2/CH4 measurements, and possibly a similar instrument for N2O submitted in a parallel FNRS proposal. These two instruments then be used to measure the three GHGS (CO2, CH4, N2O) continuously to map their surface distribution in Lake Tanganyika The data generated by this project will complete a data-set of GHGs that we are gathering in African large lakes in the frame of on-going (Lakes Edward, George, Victoria) and past projects (Kivu).

Bathymetric map of Lake Tanganyika based on the Belgian Hydrobiology mission (1946-1947)

Another bathymetric map of Lake Tanganyika based on the Belgian Hydrobiology mission (1946-1947)