Ndondo G. R. N. auteur aut IRD Probst J. L. auteur aut IRD Ndjama J. auteur aut IRD Ngoupayou J. R. N. auteur aut IRD Boeglin J. L. auteur aut IRD Takem G. E. auteur aut IRD Brunet F. auteur aut IRD Mortatti J. auteur aut IRD Gauthier-Lafaye F. auteur aut IRD Braun Jean-Jacques auteur aut IRD Ekodeck G. E. auteur aut IRD text journalArticle eng text/pdf born digital access Stream carbon fluxes are one of the major components in the global C cycle, yet the discrimination of the various sources of stream carbon remains to a large extent unclear and less is known about the biogeochemical transformations that accompany the transfer of C from soils to streams. Here, we used patterns in stream water and groundwater delta C-13 values in a small forested tropical headwater catchment to investigate the source and contribution from the soil carbon pools to stream organic and inorganic carbon behavior over seasonal scales. Stream organic carbon (DOC and POC) comes mainly from the upper rich soil organic carbon horizons and derived from total organic carbon (TOC) of biogenic source. The isotopic compositions delta C-13(TOC), delta C-13(DOC) and delta C-13(POC) of these carbon species were very close (-30 parts per thousand to -26 parts per thousand) and typical of the forested C3 vegetation. The relationship observed between DOC and log pCO(2) and delta C-13(DIC) indicated that besides the considerable CO2 evasion that occurs as DIC is transported from soils to streams, there were also other processes affecting the stream DIC pool. In-stream mineralization of DOC and mixing of atmospheric carbon had a significant influence on the delta C-13(DIC) values. These processes which varied seasonally with hydrological changes represent the main control on DOC and DIC cycling in the wet tropical milieu. The rapid turnover of carbon on hillside soils, the transformation of TOC to DOC in wetland soils and further mineralization of stream DOC to DIC favor the evasion of C, making the zone a source of carbon to the atmosphere. specialized Dissolved inorganic carbon (DIC) delta C-13 carbon isotope composition Dissolved organic carbon (DOC) Soil organic carbon mineralization Partial pressure of CO2(pCO(2)) Carbon sources CAMEROUN 062 068 27 1 1-30 2021 1380-6165 https://www.documentation.ird.fr/hor/fdi:010079139 10.1007/s10498-020-09386-8 1380-6165 [F B010079139] https://www.documentation.ird.fr/hor/fdi:010079139 https://www.documentation.ird.fr/intranet/publi/2020/07/010079139.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2020-07-31 2025-02-24 fdi:010079139 fre