The influence of hydrological seasonality and land use and cover on the relationship between dissolved organic carbon and carbon dioxide along a karst-draining large tropical river
Por:
Cuevas-Lara, D, Alcocer, J, García-Oliva, F, Sánchez-Carrillo, S, Soria-Reinoso, I, Oseguera, LA
Publicada:
1 oct 2025
Ahead of Print:
1 ago 2025
Resumen:
The partial pressure of carbon dioxide (pCO2) in rivers is influenced by carbonate weathering, soil CO2, photosynthesis, and the mineralization of dissolved organic carbon (DOC). In tropical regions, elevated temperatures intensify these processes. However, their seasonal dynamics remain poorly understood in large karst-draining rivers. This study investigated the relationship between pCO2 and DOC concentrations at both point and river reach scales in the Usumacinta River, the largest tropical watershed in North America. We assessed spatial and seasonal variations in DOC, pCO2, and CO2 air-water flux (FCO2) in relation to land use/land cover and fluvial physicochemical variables during the rainy and dry seasons. We also analyzed longitudinal changes in DOC and pCO2 (Delta DOC and Delta pCO2) along river reaches. Our results show that pCO2 was consistently oversaturated, positively correlated with DOC and cropland extent, and negatively correlated with dissolved oxygen. During the rainy season, DOC and pCO2 were positively related, as were Delta DOC and Delta pCO2, suggesting enhanced CO2 production via heterotrophic metabolism fueled by terrestrial DOC inputs. In contrast, during the dry season, Delta DOC and Delta pCO2 were negatively related, indicating DOC mineralization by river metabolism exceeds lateral DOC inputs. FCO2 increased downstream during the rainy season, particularly in lowland reaches influenced by wetlands and agriculture. These findings highlight the role of aquatic metabolism and its interactions with hydrology and land use in regulating CO2 dynamics in tropical karst rivers. Our study underscores the importance of integrating spatial and seasonal perspectives to better understand carbon cycling and greenhouse gas emissions in tropical fluvial systems.
Filiaciones:
Cuevas-Lara, D:
Univ Nacl Autonoma Mexico, Programa Posgrad Ciencias Mar & Limnol, Mexico City, Mexico
Alcocer, J:
Univ Nacl Autonoma Mexico, Grp Invest Limnol Trop, FES Iztacala, Tlalnepantla, Estado Mexico, Mexico
García-Oliva, F:
Univ Nacl Autonoma Mexico, Inst Invest Ecosistemas & Sustentabil, Morelia, Michoacan, Mexico
Sánchez-Carrillo, S:
CSIC, Dept Biogeoquim & Ecol Microbiana, Museo Nacl Ciencias Nat, Madrid, Spain
Soria-Reinoso, I:
Univ Nacl Autonoma Mexico, Programa Posgrad Ciencias Mar & Limnol, Mexico City, Mexico
Oseguera, LA:
Univ Nacl Autonoma Mexico, Grp Invest Limnol Trop, FES Iztacala, Tlalnepantla, Estado Mexico, Mexico
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