http://hdl.handle.net/10498/19462 Wed, 04 Nov 2026 21:48:54 GMT 2026-11-04T21:48:54Z http://hdl.handle.net/10498/40523 A dual solid and liquid solvent bar microextraction coupled with portable X-ray fluorescence for lead determination in seawater Cuervo Novas, Senia; Mendiguchía Martínez, Carolina; Moreno Aguilar, Carlos Trace metals play a crucial role in many biogeochemical processes in water. Due to their low concentrations and the complexity of the matrix, analysing these metals in seawater is a complex task that usually requires a previous preconcentration step. We present a simple two-step method for determining lead concentration in seawater. In the first step, we use a two-phase solvent bar microextraction system (2-SBME), previously prepared with a polypropylene hollow fiber. The extracted metal is then measured directly within the solid fiber using a portable X-ray fluorescence spectrometer. The 2-SBME contains two different extraction reagents: one liquid (Cyanex 272) and one solid (carbon nanotubes functionalized with carboxylic groups (CNT-COOH)). Two different microextraction processes are then carried out simultaneously: a LPME and a SPME, achieving a synergistic effect in the separation process. Efficiency was evaluated in terms of the percentage of lead extracted, with optimum conditions obtained at 0.06 mol L−1 of Cyanex 272, 10 mg mL−1 of CNT-COOH, a stirring rate of 50 rpm and an extraction time of 90 min. The influence of X-ray exposure time was also studied. Under optimal conditions, the LOD and LOQ were 0.061 mg L−1 and 0.203 mg L−1, respectively. Finally, the greenness of the new method was evaluated using the AGREEprep and SPMS methods. The method was successfully used to determine the lead concentration in fortified real seawater samples from three different locations, thus demonstrating its applicability. Using portable X-ray fluorescence equipment avoids the re-extraction step, and opens the possibility of in situ analysis. Thu, 01 Jan 2026 00:00:00 GMT http://hdl.handle.net/10498/40523 2026-01-01T00:00:00Z http://hdl.handle.net/10498/40513 A new polymer inclusion membrane-based system to separate and determine copper ions in saline waters Perales Pérez, Ángela; Pinto Ganfornina, Juan José; Moreno Aguilar, Carlos We present a new system to separate and determine copper concentration in saline samples. It is based on the use of a polymer inclusion membrane (PIM) to separate and preconcentrate the copper ions from the saline aqueous matrix to a receiving acidic solution. The influence of the composition and thickness of the PIM has been studied and optimised, by varying the concentration of the base polymer, extractant reagent, and plasticizer, as well as the total volume of solution used to prepare the membrane. The thinner PIM exhibited the best transport of metal ions, with the optimal thickness of 20.5 ± 1.8 μm and the composition being 30% (w/w) of cellulose triacetate (CTA), 60% (w/w) of di(2-ethylhexyl) phosphoric acid (DEHPA), and 10% (w/w) of tris(2-ethylhexyl) phosphate (TEHP). In addition, we studied the influence of the physico-chemical variables on copper transport across the membrane. Optimum results were obtained for a sample pH of 5 and a stripping phase containing 0.1 mol L−1 HNO3. The variation of copper concentration was monitored on-line by using a colorimetric reagent containing 6.67x10−5 mol L−1 of 4-(2-pyridylazo) resorcinol (PAR) in a flow injection analysis (FIA) system. A second-order mathematical relationship was obtained between the extraction time and the percentage of copper separation, enabling the application of the method to real seawater samples with different copper concentrations at the ppm and sub-ppm levels. Thu, 01 Jan 2026 00:00:00 GMT http://hdl.handle.net/10498/40513 2026-01-01T00:00:00Z http://hdl.handle.net/10498/40503 Auction-based comparisons of landings, revenue and price structures between Bonanza (Sanlucar de Barrameda) and Isla Cristina (Gulf of Cadiz, SW Spain) in 2024 Vidal Pérez, Juan Manuel; Chover Serrano, Andrés; Coronil Huertas, Daniel José; Alonso del Rosario, José Juan This study compares landings, revenues, and price structures between two major Andalusian first-sale auctions in the Gulf of Cadiz (SW Spain): Bonanza (Sanlucar de Barrameda) and Isla Cristina. Using 2024 auction records aggregated at the vessel–species level, we analyse how outcomes differ across ports and whether contrasts are driven by species composition, within-species pricing, or scale (lot-size) effects. Descriptive statistical indicators, non-parametric inference (Mann–Whitney tests) and effect-size measures are complemented with alternative price models (log-OLS, Gamma-GLM and GAM) to assess the robustness of the price–quantity relationship. Results indicate that Bonanza tends to exhibit stronger performance for the typical vessel (higher landings, higher revenues, and greater species diversification), whereas Isla Cristina concentrates a larger share of total activity, consistent with a more scale-oriented structure dominated by a subset of high-throughput vessels. Differences in average unit values between ports are largely explained by species mix and volume weights (i.e., the relative importance of high- versus low-value taxa), while composition-controlled models point to a smaller within-species port effect for Isla Cristina that varies with landed quantity. Overall, routinely collected auction data provide a consistent basis for comparing port-level market outcomes and for distinguishing whether cross-port differences arise primarily from composition, pricing, or both. Wed, 13 May 2026 00:00:00 GMT http://hdl.handle.net/10498/40503 2026-05-13T00:00:00Z http://hdl.handle.net/10498/40499 Macrofaunal diversity and secondary production in kelp holdfasts (Phaeophyceae) within a climatic transition zone Reis, B.; Franco, J.N.; Costa, D.A.; Casalís-Cantallo, H.; van der Linden, P.; Sousa-Pinto, I.; Arenas, F.; Antunes, C.; Franco Rodil, Iván Despite substantial research on kelp holdfast biodiversity, the drivers of macrofaunal diversity, abundance, and biomass across holdfast types and different climatic regions remain unresolved. This uncertainty extends to ecosystem functioning, where empirical estimates of secondary production are rare. We quantified the relative influence of regional environmental context and holdfast morphology on macrofaunal assemblages inhabiting holdfasts of Laminaria ochroleuca and Saccorhiza polyschides in two contrasting regions along the western Iberian coast climatic gradient: the northern A Coruña, Spain (COR; cooler, lower wave exposure) and the southern Peniche, Portugal (PEN; warmer, higher wave exposure). We also investigated ecological functioning by estimating secondary production. Macrofauna diversity, abundance, biomass (ash-free dry mass; AFDM), and secondary production were assessed at the holdfast level in samples collected from both regions in summer 2021. Holdfast structural complexity was quantified as surface-to-volume ratio (SA/V). Underwater Visual Census (UVC) surveys were conducted to provide reef-scale context for regional differences. Secondary production (consumer incorporation of organic matter per time) was estimated with Edgar's empirical model to infer energy-transfer dynamics. The cooler region, COR, exhibited significantly higher overall diversity and production than PEN. While S. polyschides supported lower taxonomic diversity than L. ochroleuca, it exhibited higher secondary production. These findings highlight the importance of regional climatic context in shaping kelp holdfast biodiversity and functioning. Differences between cooler and warmer regions suggest that variation in thermal regimes can be associated with changes in holdfast community structure and secondary production. Thu, 01 Jan 2026 00:00:00 GMT http://hdl.handle.net/10498/40499 2026-01-01T00:00:00Z