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title of the reference :  Iron and Manganese dynamics in the sediments of Ghar El Meleh Lagoon.
Publication Date: 2001
Author : Added Ayed
Catalogue type : Livre
Catalogue reference : N°67 (TUN) Notes Serv. Géol. N°67 Iron and Manganese dynamics in the sediments of Ghar El Meleh Lagoon. Analyses of iron and manganese in the sediment of Ghar El Melh Lagoon showed the following results : Fe and Mn hydroxides and oxides and AVS concentrations exhibited in the same decrease in the 0-10 cm depth interval.The laboratory results showed that the maximum of Fe2+ and Mn 2+ liberation occured at a depth of 15-18 cm in the sediment where SO4 2- reduction revival was observed.These results suggest that iron and manganese reduction was coupled with sulfate reduction in the sediment.The laboratory results showed that production rates of Fe2+ and Mn2+ as well as reduction rates of SO42- exhibited a Gaussian from between 5 and 36 cm in the sediment. However, in the 0-5cm depth interval, SO42- reduction was high, while Mn2+ production was low and that of Fe2+ varied with time. Additionally, the laboratory study showed a similarity between the distribution of SiO2 and SO42- rates. Pore water distribution of Fe2+,Mn2+and SO42- seems to be affected by the bioirrigation and wind action.The high benthic fluxes of Mn2+ suggested that steep gradients of Mn2+ and probably Fe2+ existed at the sediment-water interface and this does mean that bacterial reduction of Mn and Fe oxides could occur at this zone. By modeling the pore water concentrations of Fe2+ and Mn2, rates of both bioirrigation and wind action were estimated to 10dm2 y-1 in summer and 100 dm2y-1 in spring at the 0-6 cm depth interval of sefdiments. fer ; manganèse ; porosité ; interface ; sédiment lacustre ; corrélation ; Tunisie ; Tunisie Nord Orientale ; Gar El Melh Added Ayed Géochimie
Indexation decimale : Géochimie
Keywords : fer ; manganèse ; porosité ; interface ; sédiment lacustre ; corrélation ; Tunisie ; Tunisie Nord Orientale ; Gar El Melh
Summary : Analyses of iron and manganese in the sediment of Ghar El Melh Lagoon showed the following results : Fe and Mn hydroxides and oxides and AVS concentrations exhibited in the same decrease in the 0-10 cm depth interval.The laboratory results showed that the maximum of Fe2+ and Mn 2+ liberation occured at a depth of 15-18 cm in the sediment where SO4 2- reduction revival was observed.These results suggest that iron and manganese reduction was coupled with sulfate reduction in the sediment.The laboratory results showed that production rates of Fe2+ and Mn2+ as well as reduction rates of SO42- exhibited a Gaussian from between 5 and 36 cm in the sediment. However, in the 0-5cm depth interval, SO42- reduction was high, while Mn2+ production was low and that of Fe2+ varied with time. Additionally, the laboratory study showed a similarity between the distribution of SiO2 and SO42- rates. Pore water distribution of Fe2+,Mn2+and SO42- seems to be affected by the bioirrigation and wind action.The high benthic fluxes of Mn2+ suggested that steep gradients of Mn2+ and probably Fe2+ existed at the sediment-water interface and this does mean that bacterial reduction of Mn and Fe oxides could occur at this zone. By modeling the pore water concentrations of Fe2+ and Mn2, rates of both bioirrigation and wind action were estimated to 10dm2 y-1 in summer and 100 dm2y-1 in spring at the 0-6 cm depth interval of sefdiments.
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