http://hdl.handle.net/10498/6742 2026-09-21T18:46:48Z 2026-09-21T18:46:48Z Luján Martínez, María Lobo, Francisco José Bruno Mejías, Miguel De Castro, Sandra http://hdl.handle.net/10498/40232 2026-09-18T04:01:18Z 2018-01-01T00:00:00Z

Morpho-stratigraphic features of the northern shelf of the Strait of Gibraltar: Tectonic and sedimentary processes acting at different temporal scales Luján Martínez, María; Lobo, Francisco José; Bruno Mejías, Miguel; De Castro, Sandra The northern shelf of the Strait of Gibraltar adjacent to Camarinal Sill, defined here as the Cape Paloma continental shelf, has been investigated by analyzing a set of geophysical data including multibeam bathymetric images, a side-scan sonar mosaic and high-resolution seismic profiles, and the simulation of water-mass circulation patterns along the northern coastal margin. The aim of the study was to establish the significance of factors determining the evolution of this shallow margin at different temporal scales and to assess the implications for bedform generation in strait settings, taking into account the complex tectonic evolution and the energetic hydrodynamic regime of the strait. Deformed basement rocks are part of the Betic-Rif thrust wedge, western Gibraltar Arc, mainly formed by the materials of the Flysch Complex units and covered by Pliocene to Quaternary post-orogenic deposits. A central high (Bajo de los Cabezos High) is delimited by lateral depressions, that nucleated two major depocentres with distinctive filling histories. The eastern depocentre is controlled by WNW-ESE faults cutting the Cretaceous-Miocene basement rocks; these faults generate horsts and grabens that could have contributed to the opening of the Strait of Gibraltar during the Pliocene. The largest and westernmost depocentre is related to the complete infilling of a shelf palaeovalley. The sediment cover is molded by different fields of submarine dunes and comet marks that indicate the influence of hydrodynamic processes on sediment transport at the coastal margin. The observations in the study area regarding bedform development must be placed into a wider context of strait sediment dynamics. The Cape Paloma continental shelf exhibits both erosional and depositional forms, due to its intermediate location between the strait, mostly dominated by erosional processes, and the Barbate Platform (northwest of the study area), mostly characterized by depositional forms. The long-term evolution of the sediment depocentres in the study area appears to be mainly influenced by the morpho-tectonic configuration of the margin, which in turn was established to a large extent by differential uplifting along the coast. In the shelf east of the central high, the basement horst and graben structure trapped sediments in the physiographic lows and fostered the formation of large-scale sediment banks. In the shelf west of the central high, the occurrence of a major infilled palaeovalley is in agreement with a gentle subsidence trend. The physiographic configuration is also thought to play a major role in defining short-term processes, particularly in confining a cyclonic eddy to the east of the Bajo de los Cabezos High during specific conditions of the tidal cycle. This eddy favors the recirculation of sediments in the coastal margin, as evidenced by small bedform fields that apparently show a wider distribution that the larger-scale, confined sediment banks, due to the instauration of the modern sediment dynamics after the complete shelf flooding. The sediment transport pattern established in the study area seems to be eventually captured by a submarine channel that provide an efficient mechanism for sediment export toward deep-water settings, where an extensive contourite depositional system has been documented

2018-01-01T00:00:00Z Muñoz-Perez, Juan Jose http://hdl.handle.net/10498/40105 2026-07-29T04:10:09Z 2026-07-01T00:00:00Z

Recent Advances in Sediment Characterization for Beach Nourishment: Practical Developments in Sampling, Analysis and Compatibility Assessment Muñoz-Perez, Juan Jose Sediment characterization is one of the most influential stages in beach nourishment projects because it directly affects borrow sediment selection, compatibility assessment, overfill estimation and, ultimately, project performance. During the last decade, several methodological developments have progressively improved the reliability of sediment characterization by addressing practical problems frequently encountered during field sampling, laboratory analysis and engineering design. This paper reviews these developments from an engineering perspective, emphasizing representative sediment sampling within trailing suction hopper dredgers, improvements in grain-size analysis, advances in laboratory procedures, new approaches for sediment compatibility assessment and recent developments in monitoring techniques. Rather than providing an exhaustive review of beach nourishment practice, the paper summarizes a coherent sequence of methodological advances that have reduced common sources of error throughout the quality-control process. Practical recommendations are provided for engineers involved in beach nourishment design and construction, while future research needs are also discussed. The review highlights how relatively simple methodological improvements can substantially increase the reliability of engineering decisions without increasing project complexity or cost.

2026-07-01T00:00:00Z Ramírez-Perez, Juan Antonio Gázquez González, Manuel Jesús González Barrionuevo, Felipe Jesús Bolívar, Juan Pedro http://hdl.handle.net/10498/39954 2026-07-07T04:00:18Z 2026-06-16T00:00:00Z

Analysis of the Chemical and Radiological Risks Associated with Wastes from Mining in the Iberian Pyrite Belt Ramírez-Perez, Juan Antonio; Gázquez González, Manuel Jesús; González Barrionuevo, Felipe Jesús; Bolívar, Juan Pedro Mining activities in the Iberian Pyrite Belt have generated large volumes of legacy wastes that may pose both environmental and radiological concerns, potentially limiting their reuse and valorization. However, integrated assessments combining chemical, mineralogical, and radiological characterization of these materials remain scarce. In this work, representative mining wastes from twelve sites across the Iberian Pyrite Belt were investigated through X-ray fluorescence, X-ray diffraction, scanning electron microscopy, standardized leaching tests, alpha and gamma spectrometry, and radon emanation measurements. The results revealed significant enrichment in potentially toxic elements, particularly Cu, Zn, Pb, and As, with concentrations exceeding local soil background values by up to several orders of magnitude. Leaching tests identified oxidized sulfide-rich residues as the materials with the highest pollutant mobility and greatest acid-generating potential. In contrast, radiological characterization showed that uranium-series, thorium-series radionuclides, and 40K activities, together with radiological hazard indices and radon exhalation rates, were generally comparable to those of surrounding natural soils and remained below internationally recommended limits. These findings indicate that chemical contamination represents the main environmental constraint of these wastes, whereas radiological impact is generally low, supporting their case-by-case evaluation for remediation, valorization, and potential exclusion from radiological control.

2026-06-16T00:00:00Z Ramírez-Perez, Juan Antonio Soto Cruz, Francisco Javier Gázquez González, Manuel Jesús Pérez-Moreno, Silvia María Bolívar, Juan Pedro http://hdl.handle.net/10498/39768 2026-09-01T08:20:20Z 2026-01-07T00:00:00Z

Iron recovery from water clarification sludge as ferric chloride Ramírez-Perez, Juan Antonio; Soto Cruz, Francisco Javier; Gázquez González, Manuel Jesús; Pérez-Moreno, Silvia María; Bolívar, Juan Pedro The circular economy (CE) promotes strategies aimed at waste minimization, treatment, and resource recovery, integrating industrial development with environmental and socioeconomic priorities. In this context, the present study investigates the recovery of iron from an oil refinery sludge generated during the water clarification stage of a steam production plant. This residue exhibits a high iron content (37 wt.%), highlighting its potential as a secondary raw material and alternative iron source. Iron recovery was carried out by hydrochloric acid (HCl) leaching under different operating conditions, including HCl concentration, reaction time, temperature, and solid/liquid ratio (S/L). These parameters were investigated to optimize iron dissolution and obtain ferric chloride, a coagulant widely used in water treatment processes. Optimal leaching conditions (37 wt.% HCl, room temperature, 24 h of agitation, S/L = 1/3.5) produced leachates containing 13.4 wt.% Fe, a value comparable to that of commercial ferric chloride solutions (≈ 14 wt.%). The recovered ferric chloride was subsequently evaluated as a coagulant in three types of water (irrigation, tap, and distilled water). Removal efficiencies of up to 98.7% for Fe, 95.2% for Cr, 99.8% for Zn, 82.4% for Cu, and 82.6% for As were achieved. These efficiencies are comparable to or approaching those obtained using a commercial reagent. The results demonstrate the technical feasibility of valorizing oil refinery sludge into a marketable coagulant, providing environmental benefits while supporting circular economy principles.

2026-01-07T00:00:00Z