Modern sedimentation patterns and human impacts on the Barcelona continental shelf (NE Spain)
Liquete García, Camino (Universitat de Barcelona. Grup de Recerca Consolidat en Geociències Marines)
Lucchi, Renata Giulia (Universitat de Barcelona. Grup de Recerca Consolidat en Geociències Marines)
Garcia-Orellana, Jordi (Universitat Autònoma de Barcelona. Departament de Física)
Canals Artigas, Miquel (Universitat de Barcelona. Grup de Recerca Consolidat en Geociències Marines)
Masqué Barri, Pere (Universitat Autònoma de Barcelona. Departament de Física)
Pascual Mas, Catalina (Universitat de Barcelona. Grup de Recerca Consolidat en Geociències Marines)
Lavoie, Caroline (Universitat de Barcelona. Grup de Recerca Consolidat en Geociències Marines)

Data:	2010
Resum:	Seafloor sediments were collected from the Barcelona continental shelf, NE Spain, to determine the textural characteristics and sedimentary processes related to different depositional systems and human pressures. The Barcelona continental shelf is principally influenced by the discharge of the Llobregat and Besòs rivers, and also by anthropogenic modifications Duch as the diversion of the Llobregat River or the enlargement of the Port of Barcelona. Sedimentological, physical and biogeochemical properties of 14 sediment cores and grabs indicate the presence of three distinct depositional environments linked to river-influenced, marine-influenced and mixed sedimentation. Sedimentological results have been used to groundtruth available backscatter data. The river-influenced environment, mainly associated to the Llobregat River input, does not reach the shelf edge as the prevailing oceanographic currents deflect sediments south-westward. Riverine sediments are fine-grained, with abundant plant debris, micas and relatively high organic carbon content. The associated sedimentary features are the Holocene prodelta and two modern mud patches. The marine-influenced environment extends north-easterly over the middle and outer shelf and on the upper continental slope. The sediments are coarser grained with abundant bioclasts and lower organic carbon content. Mixed sedimentation is present between the river- and marine-influenced areas. In addition, 210Pb, 226Ra and 137Cs radiometric analyses were used to estimate accumulation rates as well as to identify sites with disturbed sedimentation. Relatively high sediment accumulation rates (up to 0. 70-1. 03 g•cm-2•yr-1 equivalent to 6. 4-10 mm•yr-1) are estimated on the Llobregat prodelta while moderate rates 0. 21-0. 46 g•cm-2•yr-1 or 1. 6-3. 6 mm•yr-1) are found between the Besòs and the Llobregat outlets. Two sediment cores show a sharp change from river-influenced to marine-dominated conditions that occurred in the mid- 1960s. This is interpreted as a significant regression (~2. 5 km in 40 years) of the river-influenced domain that may be associated to the extension of the Port of Barcelona and the canalization of the Besòs River, amongst other reasons. Other important human impacts observed in the Barcelona continental shelf are (i) sediment mixing by dredging, ship anchoring and trawling; and (ii) possible organic pollution associated to river and sewage discharges.
Drets:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan aquestes es distribueixin sota la mateixa llicència que regula l'obra original i es reconegui l'autoria de l'obra original.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Matèria:	Controlled source electromagnetics ; Robust processing ; Response functions ; Phase difference
Publicat a:	Geologica acta, Vol. 8, Núm. 2 (Juny 2010) , p. 169-187, ISSN 1696-5728

Adreça alternativa: https://raco.cat/index.php/GeologicaActa/article/view/202691
Adreça alternativa: https://revistes.ub.edu/index.php/GEOACTA/article/view/105.000001528
DOI: 10.1344/105.000001528

22 p, 1.8 MB

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