Geochemistry of coastal wetland in the Northern Saharan environment through lacustrine sediment core THI
2020
Nogueira, Juliana | Evangelista, Heitor | Bouchaou, Lhoussaine | Moreira, Luciane Silva | Sifeddine, Abdelfettah | ElMouden, Ahmed | Msanda, Fouad | Caquineau, Sandrine | Briceño-Zuluaga, Francisco Javier | Licínio, Marcus Vinicius | Mandeng-Yogo, Magloire | Mendez-Millan, Mercedes | Cordeiro, Renato Campello | Knoppers, Bastiaan | Moreira-Ramírez, Manuel | Martins, Renato
The core was collected manually from a boat employing a gravity core sampler. The core was sliced every two centimeters in the field, packed in individual identified plastics bags, and kept refrigerated. The THI sediment core (N 27°59.139, W 12°17.109), located in the inner portion of the Lagoon, was retrieved from a secondary channel, having 52 cm of length. The salinity measured at the site on the day of the sampling was 50 PSU, thus revealing a saline gradient that increases towards the upstream, probably due to a longer residence time of the water and consequent higher evaporation rate at that site. To its right side, the secondary channel is protected by a desert plateau, while to its left lays a saltmarsh area, occupied by specimens of the genus Salicornia sp., that are periodically exposed by tidal dynamics. A low marine influence characterizes this part of the Lagoon, depths between 2.70 m and 5.20 m, during low and high tides, respectively, and surrounded by extensive heterogeneous marshes. Aiming the recognition of the environmental changes at this point of the lagoon, we have performed the following measurements in the core's sediments: dating (210Pb and 137Cs calibration), sedimentation rate, mean grainsize, Chlorophyll, Total Organic Carbon (TOC), C/N, Sr/Ca and Si/Ti elemental ratios.
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