The need to correct for the Suess effect in the application of δ13C in sediment of autotrophic Lake Tanganyika, as a productivity proxy in the Anthropocene

The change in dissolved inorganic delta C-13 in the ocean resulting from the change in delta C-13 in atmospheric CO2 owing to anthropogenic activities (the Suess effect) is well known. The need to correct for the Suess effect when applying delta C-13 in organic matter in lacustrine sediment deposited during the anthropocene as a productivity proxy, is widely although not universally acknowledged. This paper reviews conceptions about the Suess effect in lacustrine delta C-13(org) and methods to adjust for the Suess effect when delta C-13(org) is used to infer recent changes in aquatic productivity. Lake Tanganyika is used as an example to illustrate the necessity of the correction. When the Suess effect is not considered, interpretations of sediment core data can result that are opposite to those achieved with the correction applied, as is here shown in Lake Tanganyika and in other lakes. A new method to correct for the Suess effect is provided which has the advantage of being applicable to data for a larger period (1700-2000) than methods currently available. In addition, Lake Tanganyika is shown to be a net sink for CO2.