Resumen

RUA, Alex; PALACIO BAENA, Jaime  y  FLOREZ MOLINA, María Teresa. Relation of hydrological pulse to sediment stratigraphy in the Ayapel Flood Plain Lake, Colombia. Rev.fac.ing.univ. Antioquia [online]. 2014, n.70, pp.197-206. ISSN 0120-6230.

The hydrological pulse and matter transfer between tributaries and wetlands link terrestrial and rheotrophic environments. The water-sediment interaction on multidecadal scale within wetlands of Colombian Atlantic savannahs remains greatly unknown. This study stratigraphically correlated nine sediment cores (13-30 cm) spanning ca. 110-600 years BP from the Ayapel Flood Plain Lake (AFPL). These correlations framed (i) zones of high anthropogenic pressure, (ii) main hydrodynamics, and (iii) organic matter (OM) contributions. More than 84 % out of the 150 km²-extension of the AFPL was comprised of oxic mineral sediment that is object to early diagenesis. In contrast, methanogenesis was evinced by reduced sediment of anaerobic strata in adjacent marshes. The intensity of the hydrological pulse matched the stratified deposit of the rhizome from Eichhornia crassipes. Whereas sand and gravel were deposited under turbulent flow near the Quebradona tributary, clayish silt deposited at pelagic zones and sandy silt at waterways. The wind drag on the shallow-water surface enhanced resuspension and transport of the sediment that was originally contributed by fluvial inputs. Thus, relatively slow net sedimentation rates were proposed at Quebradona's mouth (ca. 0.15 cm a^-1), channels (ca. 0.1 cm a^-1) and temporal marshes (ca. 0.05 cm a^-1). In addition, the sediment of the AFPL exported the degradation products of the OM to the lower reaches of the San Jorge River and the atmosphere.

Palabras clave : Flood Plain Lake; hydrological pulse; tributary; sediment; stratigraphy; methanogenesis; Eichhornia crassipes.

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