The correlations between various sedimentological and geochemical parameters permit to identify the main sedimenta tion phases of pollution carriers, especially those related to the sediment cores lithology in Bizerte...The correlations between various sedimentological and geochemical parameters permit to identify the main sedimenta tion phases of pollution carriers, especially those related to the sediment cores lithology in Bizerte Lagoon. A close re lationship exists between the TOC distribution and the fine fraction (r = 0.70;threshold 5%). This is to identify the for mation of organic minerals aggregates. Significant correlations between specific organic matter and heavy metals have been identified. Indeed, the calculated correlation coefficient varies between 0.4 for Zn and 0.85 for Mn. The enrich ment of the intermediate horizons in heavy metals result in specific sedimentations episodes of the prodeltaic zones. Under these conditions, the surface sediments profit from a “salting-out” phenomenon, which explains the excess of lead observed on the surface. The enriched zones in manganese and zinc correspond to the strongest contents of kaolin ite and in smectite, thus, there would be an association with the finest phyllosilicates and/or the colloidal oxyhydroxy des. This is primarily due to the formation of an organic minerals complex via the trapping phenomenon of the argilla ceous particles (smectite) and the organic matter of anthropogenic origin. It is to be specified that the presence of metal elements of natural origin (Mn) or anthropogenic origin (Fe, Zn, Pb and Ni) which induce the consolidation of these organic minerals complexes.展开更多
<span style="font-family:Verdana;">The determination of geoid models with great precision (centimeter) was always at the center of interest in geodesy research [<a href="#ref1">1</a&...<span style="font-family:Verdana;">The determination of geoid models with great precision (centimeter) was always at the center of interest in geodesy research [<a href="#ref1">1</a>] [<a href="#ref2">2</a>]. One of the most used methods to calculate the geoid model is the method called Remove-Compute-Restore (R-C-R). This method applies the stokes’ integral formula by the use of short, medium and long wavelength information via the three main stages R-C-R. The GravSoft software implemented by [<a href="#ref3">3</a>] was used for this study. Geodetic heights, a digital terrain model (SRTM) and leveled GPS points were used as inputs. The geoid modeling was carried out on the North region of Tunisia (Grand Tunis and Bizerte) on an area of 83 × 83 km. The accuracy of the quasi-geoid provisional reached 3.1 cm.</span>展开更多
文摘The correlations between various sedimentological and geochemical parameters permit to identify the main sedimenta tion phases of pollution carriers, especially those related to the sediment cores lithology in Bizerte Lagoon. A close re lationship exists between the TOC distribution and the fine fraction (r = 0.70;threshold 5%). This is to identify the for mation of organic minerals aggregates. Significant correlations between specific organic matter and heavy metals have been identified. Indeed, the calculated correlation coefficient varies between 0.4 for Zn and 0.85 for Mn. The enrich ment of the intermediate horizons in heavy metals result in specific sedimentations episodes of the prodeltaic zones. Under these conditions, the surface sediments profit from a “salting-out” phenomenon, which explains the excess of lead observed on the surface. The enriched zones in manganese and zinc correspond to the strongest contents of kaolin ite and in smectite, thus, there would be an association with the finest phyllosilicates and/or the colloidal oxyhydroxy des. This is primarily due to the formation of an organic minerals complex via the trapping phenomenon of the argilla ceous particles (smectite) and the organic matter of anthropogenic origin. It is to be specified that the presence of metal elements of natural origin (Mn) or anthropogenic origin (Fe, Zn, Pb and Ni) which induce the consolidation of these organic minerals complexes.
文摘<span style="font-family:Verdana;">The determination of geoid models with great precision (centimeter) was always at the center of interest in geodesy research [<a href="#ref1">1</a>] [<a href="#ref2">2</a>]. One of the most used methods to calculate the geoid model is the method called Remove-Compute-Restore (R-C-R). This method applies the stokes’ integral formula by the use of short, medium and long wavelength information via the three main stages R-C-R. The GravSoft software implemented by [<a href="#ref3">3</a>] was used for this study. Geodetic heights, a digital terrain model (SRTM) and leveled GPS points were used as inputs. The geoid modeling was carried out on the North region of Tunisia (Grand Tunis and Bizerte) on an area of 83 × 83 km. The accuracy of the quasi-geoid provisional reached 3.1 cm.</span>
