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Acetic acid (HOAc) and diethylenetriaminepentaacetic acid (DTPA) single extraction agents were evaluated as screening methods to estimate the mobility of some trace elements in coastal sediments from Algeciras Bay. Sediments’ total metal concentrations of most heavy metals were found to be high around the areas impacted by anthropogenic activities such a sewage, atmospheric deposition and industrial activities, with notable values for As, Ni, Cr, Pb and Cd. The order of significant extraction efficiencies obtained with DTPA, were as follows: Pb (25.65%), Cu (19.78%), Cd (14.80%) and Zn (11.25%), while those obtained with HOAc were: Mn (33.00%), Tl (24.88%), Pb (18.99%), Cd (13.59%) and Co (11.78%). The comparison between the risk assessment codes (RAC) and the percent metal extractable fractions provided results of serious concern. Very high risk values of Cu, Zn, Cd and Pb extracts in DTPA were observed near the metallurgical industry, with Mn and Tl in HOAc extracts showing high risk values near the same industrial area and harbour activities. Sediments’ total metal concentrations were compared with the Low Alert-Level (LAL) sediment quality guidelines, where Co, Pb, Zn and Ni in both extractants and Cd and Cu in DTPA as well as Tl extracted in HOAc exceeded the LAL values respectively. The Spearman Rank test showed positive correlations between Co, Cu, Ni and Zn in DTPA extracts and their corresponding total metal concentrations, with Co, Cr, Fe, Ni, Tl and Zn in HOAc and total concentrations showing positive correlations. Furthermore, higher positive correlations were found between both extraction methods for Co (ρ = 0.797), Cu (ρ = 0.777), Ni (ρ = 0.789) and Zn (ρ = 0.942), indicating comparable potential extraction efficiencies between these extractants for these metals in the sediment studied. Keywords: Acetic acid, DTPA, Coastal sediment, Single extraction, Trace-element mobility

An efficient assisted transport of Fe(III) ions using a bulk liquid membrane containing 2-hydroxybenzaldeyde benzoylhydrazone in toluene has been applied as a separation and preconcentration process for the analysis and speciation of dissolved iron traces in natural and sea waters. A study strategy based on a modified simplex design has been followed to optimise the transport of Fe(III) ions through the liquid membrane. Maximum carrier-mediated transport efficiencies were obtained at following conditions: pH 1.9 for feed aqueous solution; 0.014 mol L− 1 of ligand in toluene as carrier and 2.9 mol L− 1 HNO3 in the stripping solution. Under optimal conditions, the average recovery of Fe(III) ions was 102 ± 2% (n = 7) for 6 h at 35 °C and the preconcentration factor of the method was 18.1. The influence of saline matrix was negligible and experiments at slightly high temperatures led to reduced preconcentration times. The accuracy of the method was verified by using the TMDA-62 certified reference water sample and successfully applied to the analysis of Fe(III) in river and seawater samples from Tangier (Morocco). Due to the proposed liquid membrane system allowed the selective separation and preconcentration of Fe(III) ions but not Fe(II) ions, a scheme for speciation analysis of dissolved iron was proposed. The distribution of total dissolved Fe, non-labile Fe, labile Fe(II) and labile Fe(III) fractions was performed in real seawater samples with successful results in good agreement with those obtained by adsorptive cathodic stripping voltammetry (average relative error of ± 3%).

A comprehensive approach to chemical accumulation and biological effects of short-term Cu exposure in juveniles of European seabass (Dicentrarchus labrax) has been achieved. Fish were exposed to 0.01–10 mg L− 1 nominal Cu concentrations for 24–96 h. Metal concentrations in water and gills, liver, muscle and brain tissues were studied along with oxidative stress biomarkers (superoxide dismutase, catalase, glutathione peroxidase, lipid peroxidation). Induction of oxidative damage was observed in all the organs with differential antioxidant responses; gills appearing as the most sensitive from low environmentally water Cu concentrations as 0.01 mg L− 1. Histopathological alterations were also observed in liver and gills, even without a significant Cu accumulation. The results show that the combination of oxidative stress parameters, particularly lipid peroxidation and glutathione peroxidase activities, and histopathological alterations provide a good model fish and reliable early biomarkers for monitoring Cu pollution in seawater and might call for the protection agencies to revise the Cu environmental standards.

A novel polymer inclusion membrane (PIM), doped with pyridine-2-acetaldehyde benzoylhydrazone (2-APBH) as extractant, was synthesized and applied for the simultaneous extraction and preconcentration of Cu(II), Ni(II) and Cd(II) ions from natural waters of different salinities. Poly(vinyl chloride) (PVC) and tributyl phosphate (TBP) were used to prepare the polymeric membrane. The carrier-mediated extraction of Cu(II), Ni(II) and Cd(II) ions by PIM was based on the reaction of 2-APBH as a polydentate ligand, forming uncharged chelates at pH 8. After a back-extraction step from the membrane to an acid solution (0.3 mol L-1 nitric acid), these ions were quantitative determined by flame atomic absorption spectroscopy. The optimum values of different analytical variables were determined by using the modified simplex method. The results showed limits of detection of 0.33 µg L-1 for Cu(II), 0.75 µg L-1 for Ni(II) and 0.48 µg L-1 for Cd(II). The accuracy was successfully assessed by analyzing a certified reference river water (LGC 6019). The applicability of the proposed PIM on real samples was also demonstrated on estuarine and seawater samples, with high salinities.

A single-use optical sensor was designed for Zn(II) determination based on the immobilisation of the colorimetric reagent 2-acetylpyridine benzoylhydrazone (2-APBH) in a polymer inclusion membrane (PIM) adhered on the surface of an inert rectangular strip of polyester (Mylar). Different components for the membrane preparation were tested and those resulting in membrane with good appearance, proper physical and optical properties and ease of preparation were selected. Factorial design 23 with three replicates of the central point was applied for the optimisation of the membrane composition. The optimal composition consisted of 2.5 g of poly(vinyl chloride) (PVC), 4 mL of tributyl phosphate (TBP) and 0.04 g of 2-APBH. The optode showed a linear dynamic range from 0.03 (detection limit) to 1 mg L−1 of Zn(II) ions with a response time of 30 min in aqueous solution at pH 6 and a relative standard deviation of 3.90% for 0.4 mg L−1 of Zn(II). The sensor exhibited good selectivity to Zn(II) over other commonly ions. It was successfully applied to the determination of Zn(II) in a water certified reference material, spiked tap water, vitamin-mineral drink, food supplement and foot health care products, as contribution to the concern about this heavy metal due to its significant role in many biological and physiological processes although toxicant at high doses.

A study to determine total and mobile heavy metals concentrations in sediments from Algeciras Bay was performed and pollution hotspots were identified. The effects on aquatic organisms were established using sediment quality guidelines (SQGs). Ni and Cr exceeded the effect range medium and low levels, respectively, around industrial area. Potential toxicity of metals was determined by diethylenetriaminepenta-acetic acid (DTPA) extractions and low alert levels of Co, Cu, Zn, Cd, Ni and Pb were exceeded at most sampling sites. Three pollution indicators were used showing significant values for As, Ni, Cr, Pb and Cd. Sediment speciation using the sequential extraction BCR procedure was carried out, being Cd, Zn, Pb and As the most available metals. Principal component, cluster and ANOVA analyses were performed in order to assess the sources of metals and the influence of seasonality and anthropogenic activities on the sediment quality. Two principal component analysis (PCA) factors were obtained identifying the sampling sites affected by anthropogenic activities; Ni–Cr and Zn–Cu–V clusters were also obtained associated with stainless steel and petrochemical industrial activities. ANOVA showed the outstanding sites because of total metal concentration and significant differences among sampling sites by the acid extractable and reducible fractions for all metals except for Ba and V.