Comprehensive Assessment and Potential Ecological Risk of Trace Element Pollution (As, Ni, Co and Cr) in Aquatic Environmental Samples from an Industrialized Area.

A global assessment of arsenic (As), nickel (Ni), cobalt (Co) and chromium (Cr) was performed in environmental samples from an important industrial bay. Different fractions of water, sediments and tissues from four species of fish were analysed. Samples were collected from selected sampling sites during four consecutive samplings in spring and autumn seasons, in order to evaluate concentrations and their possible correlations among the aquatic compartments. While a higher availability of Cr and Ni was found in water, Co and As were the most available elements in sediments. In fish, the liver was the tissue with the highest proportion of As and Co, and gills showed the highest concentrations of Ni and Cr. Significance differences were observed among sites showing the pollution sources. In sediments, high correlations were found between total Co content and the most available fractions. Total Ni content highly correlated with the oxidisable fraction, while Cr total content tightly correlated with the least available fractions. Quality guideline values for sediments were frequently exceeded. In sediments and biota, concentrations were slightly higher than in other ecosystems, indicating that maritime, industrial and urban activities are affecting this type of ecosystem with great anthropogenic influence.

Design and optimization of a single-use optical sensor based on a polymer inclusion membrane for zinc determination in drinks, food supplement and foot health care products.

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.

Disposable optical sensor for Al(III) ions determination by coupled colorimetric solid-phase extraction-reflectance spectroscopy in leachates from cookware, antacids and hygienic care products.

A disposable and miniaturised optical sensor based on colorimetric solid-phase extraction has been designed using poly(styrene-divinylbenzene) membrane disks modified with the colorimetric reagent pyridoxal salicyloylhydrazone to determine the aluminium concentration in aqueous solutions. The extraction of Al(III) ions by the reagent immobilised onto a disk allows the quantification directly on the adsorbent surface by a miniature portable reflectance spectrometer with an optical fibre at 434 nm. The optimisation of the sensing system was carried out by a fractional factorial design 33-1 considering the extraction pH, amount of ligand immobilised onto the disk and time of immobilisation as experimental factors. The linear dynamic range of the sensor response ranged from 0.18 to 2 mg L-1 Al(III) with a detection limit of 0.18 mg L-1 (n = 10), being the precision of 6.3% for 1 mg L-1 Al(III) (n = 10, confidence level of 95%). The proposed method was successfully applied to the analysis of aluminium in leachates from cookware, antacids and hygienic care products, as contribution to the concern about aluminium as a known systemic toxicant at high doses.

Coupling liquid membrane and flow-injection technique as an analytical strategy for copper analysis in saline water.

A tandem system based on the coupling of a bulk liquid membrane and a flow injection analysis for the separation, preconcentration and spectrophotometric determination of copper in saline water is presented. The ligand pyridine-2-acetaldehyde benzoylhydrazone has been used as a carrier in the liquid membrane as well as a spectrophotometric reagent for UV-VIS detection. Simultaneous and sequential experimental designs were used to optimise the chosen variables of each technique, respectively. The metal was separated and preconcentrated from the sample with an efficiency of 100.5 ±â€¯0.9% and a metal preconcentration factor of 16.1. The on-line FIA determination was accomplished after metal complexation by the reagent at pH 3. A linear response was obtained in a range from 6.9 to 984.5 µg L-1 Cu(II), providing a detection limit of 1.8 µg L-1. Saline matrix and other metal ions were not cause of interferences with relative errors below 4.6% for 50 µg L-1 of Cu(II) determination. The proposed tandem system was successfully tested using a TMDA-62 certified reference material providing a relative error of + 1.9%; it was also applied to the Cu(II) determination in coastal seawater samples with low relative errors ranging from - 3.8% to 0.0% (using DPASV as reference method).

Biomarker responses of Cu-induced toxicity in European seabass Dicentrarchus labrax: Assessing oxidative stress and histopathological alterations.

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 0.01-10mgL-1 nominal Cu concentrations for 24-96h. 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 0.01mgL-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.

Histopathological alterations in Senegal sole, Solea Senegalensis, from a polluted Huelva estuary (SW, Spain).

As a component of a large research project to evaluate the effects of contaminants on fish health in the field, histopathological studies have been conducted to help establish causal relationship between pollutants (heavy metals and aromatic polycyclic hydrocarbons--PAHs) and histopathological responses in Senegal sole, Solea senegalensis, from an estuary of SW Spain. Heavy metals (As, Zn, Cd, Pb, Cu and Fe) and 16 PAHs (proprietary USEPA) concentrations in water, sediment and tissues (liver and gills) and histopathological alterations in S. senegalensis from three sampling sites of Ria de Huelva estuary during 2004-2006 years have been analysed. The histopathological studies revealed seasonal and spatial differences in the lesion grade of alterations observing the highest lesion grades in fish from Odiel River and autumn season. No significant differences were observed in the alterations prevalence between sampling sites, but significant differences were observed between seasons observing the highest prevalence in autumn season. However, calculated IPAT demonstrated a low-moderate impact of pollutants on health fish. Correlations between histopathological alterations and pollutants analysed were observed being heavy metals the group that presented a major number of correlations with alterations in several organs of S. senegalensis. In evaluating the general health of fish, the use of histopathological studies in recommended for making more reliable assessment of biochemical responses in fish exposed to a variety of environmental stressors. Statistical analysis using semiquantitative data on pathological lesions can help to establish correlation between cause (stressor) and effect (biomarker).

Solid phase extraction of copper traces using poly(styrene-divinylbenzene) membrane disks modified with pyridoxal salicyloylhydrazone in water samples.

A simple technique for the isolation, concentration and matrix simplification of Cu(II) ion in natural waters is proposed. This method has been developed using poly(styrene-divinylbenzene) membrane disks modified with the synthesized ligand pyridoxal salicyloylhydrazone (PSH). The retained ions on the disks were eluted with 10 mL 1 mol L(-1) HNO(3) and measured by flame atomic absorption spectrometry at 324.8 nm. The influence of pH, amount of ligand, type and amount of eluent for the stripping of copper ion from the membrane over extraction efficiency were evaluated. Extraction efficiencies >99% were obtained by elution of the disks with minimal amount of solvent with a preconcentration factor up to 100. The precision of the method for 10 replicate measurements of aqueous solutions containing 40 µg L(-1) Cu(II) was 1.5% at significance level of 95%. The breakthrough volume for 5 µg of Cu(II) was found to be 1000 mL and the detection limit of the method was 4 ng L(-1) of metal ion. The present method was successfully applied to the extraction and determination of copper in lake and sea waters.

Assessment of the metal pollution, potential toxicity and speciation of sediment from Algeciras Bay (South of Spain) using chemometric tools.

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.

An efficient approach to designing and optimizing the analysis of Ni(II) by AdCSV in seawater.

A highly sensitive voltammetric method was developed for the determination of nickel in seawater at nanomolar concentrations. The measurement is based on the differential pulse cathodic adsorptive stripping of Ni(II) complexed with pyridoxal salicyloylhydrazone at a hanging mercury drop electrode. Optimal conditions were found following a two-step study strategy based on a Plackett Burman design and subsequently a modified simplex method. They were: deposition potential -0.8 V; deposition time 120 s; differential pulse scan mode; pulse amplitude -0.07 V; pulse time 0.04 s; voltage step 0.017 V; time interval for voltage step 0.05 s; supporting electrolyte ammonium chloride/ammonia (0.08 M, pH=8.9) and concentration of PSH 5.32 × 10(-6)M. The response of the system was found to be linear in a range of Ni concentrations from 0 to 306.7 × 10(-9)M. The detection limit was found to be 0.04 × 10(-9)M of Ni(II). The precision of the method was 1.4% for 3.4×10(-8)M of Ni(II) and 1.48% for the blank at a significance level of 95% (n=9). The method was free from interferences of inorganic salts and trace metals at usual concentrations in seawater. The application to seawater was demonstrated by analysis of CRM 505 and LGC 6016 certified reference estuarine water and real seawater samples from Tangier Bay (Morocco).

Sensitive adsorptive stripping voltammetric method for determination of lead in water using multivariate analysis for optimization.

A sensitive adsorptive cathodic stripping voltammetric (AdCSV) method is presented for direct determination of Pb(II) at nanomolar levels in water based on metal complexation with 2-acetylpyridine salicyloylhydrazone (2-APSH) and subsequent adsorptive deposition onto hanging mercury drop electrode (HMDE). The instrumental and chemical factors were optimized using exploratory (Plackett-Burman) and sequential (Simplex) designs. Under optimal conditions (pH 5.6, -0.552 V for deposition voltage, 0.0083 V for voltage step and 0.87 s for time interval for voltage step) a limit of detection of 0.17 nM was obtained and the relative standard deviation of five measurements of 17.3 nM was 1.20%. The voltammetric responses increased linearly with metal ion concentrations ranging from 2.4 to 145 nM. The method was free from interferences of inorganic salts and trace metals usually present in seawater. The proposed method was successfully validated using certified reference estuarine water (LGC 6016) with relative error of -2.15% and applied to real seawater samples (relative errors of -4.40% and +1.84%).

A permeation liquid membrane system for determination of nickel in seawater.

The use of a permeation liquid membrane system for the preconcentration and separation of nickel in natural and sea waters and subsequent determination by atomic absorption spectroscopy is presented. 2-Hydroxybenzaldehyde N-ethylthiosemi-carbazone (2-HBET) in toluene is used as the active component of the liquid membrane. A study strategy based on a simplex design has been followed. Several chemical and physical parameters were optimized. Maximum permeation coefficient was obtained at a feed solution pH of 9.4, 0.3mol l(-1) of HNO(3) in the stripping solution and 1.66mmol l(-1) of 2-HBTE in toluene as carrier. The precision of the method was 4.7% at 95% significance level and a detection limit of 0.012microg l(-1) of nickel was achieved. The preconcentration procedure showed a linear response within the studied concentration range from 3 to 500microg l(-1) of Ni in the feed solution. The method was validated with different spiked synthetic seawater and certified reference water samples: TMDA-62 and LGC 6016, without matrix interferences and showing good concordance with the certified values, being the relative errors -5.9% and -2.2%, respectively. Under optimal conditions, the average preconcentration yield for real seawater samples was 98+/-5%, with a nickel preconcentration factor of 20.83 and metal concentrations ranging between 2.8 and 5.4microg l(-1).