Spatial and seasonal contrasts of sedimentary organic matter in floodplain lakes of the central Amazon basin
Sobrinho, R.L; Bernardes, M.C.; Abril, G.; Kim, J.-H.; Zell, C.I.; Mortillaro, J.M.; Meziane, T.; Moreira-Turcq, P.; Sinninghe Damsté, J.S. (2016). Spatial and seasonal contrasts of sedimentary organic matter in floodplain lakes of the central Amazon basin. Biogeosciences 13: 467-482. dx.doi.org/10.5194/bg-13-467-2016
In: Gattuso, J.P.; Kesselmeier, J. (Ed.) Biogeosciences. Copernicus Publications: Göttingen. ISSN 1726-4170; e-ISSN 1726-4189, more
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| Authors | | Top |
- Sobrinho, R.L, more
- Bernardes, M.C.
- Abril, G., more
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- Kim, J.-H., more
- Zell, C.I., more
- Mortillaro, J.M.
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- Meziane, T.
- Moreira-Turcq, P.
- Sinninghe Damsté, J.S., more
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| Abstract |
In this study, we investigated the seasonal andspatial pattern of sedimentary organic matter (SOM) in fivefloodplain lakes of the central Amazon basin (Cabaliana,Janauaca, Canaçari, Mirituba and Curuai) which have differentmorphologies, hydrodynamics and vegetation coverages.Surface sediments were collected in four hydrologicalseasons: low water (LW), rising water (RW), high water(HW) and falling water (FW) in 2009 and 2010.We investigatedcommonly used bulk geochemical tracers such as theC V N ratio and the stable isotopic composition of organic carbon(?13Corg/. These results were compared with lignin phenolparameters as an indicator of vascular plant detritus andbranched glycerol dialkyl glycerol tetraethers (brGDGTs) totrace the input of soil organic matter (OM) from land to theaquatic settings. We also applied the crenarchaeol as an indicatorof aquatic (rivers and lakes) OM. Our data showed thatduring the RW and FW seasons, the surface sediments wereenriched in lignin and brGDGTs in comparison to other seasons.Our study also indicated that floodplain lake sedimentsprimarily consisted of allochthonous, C3 plant-derived OM.However, a downstream increase in C4 macrophyte-derivedOM contribution was observed along the gradient of increasingopen waters – i.e., from upstream to downstream. Accordingly,we attribute the temporal and spatial difference inSOM composition to the hydrological dynamics between thefloodplain lakes and the surrounding flooded forests. |
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