José Usero

Trace metals in the bivalve molluscs Ruditapes decussatus and Ruditapes philippinarum from the atlantic coast of Southern Spain

Total concentrations of Cu, Zn, Mn, Ni, Cr, Cd, Pb, Fe, As, and Hg were determined in two marine bivalves R. decussatus and R. philippinarum from the Southern Spanish Atlantic Coast. The concentrations of Fe, Ni, Cr, Cu, and As in R. decussatus were significantly higher (p<0.01) than in R. philippinarum; however, R. philippinarum contained more Hg. The levels of Cu, Zn, Pb, Hg, Cd, and Mn were significantly higher (p<0.01) in the samples taken in the Province of Huelva than in the samples from the Province o f Cadiz. According to Spanish legislation, all the samples analysed were suitable for human consumption. Three kinds of relationships between metal concentration and the size of R. decussatus and R. philippinarum were found: positive for As, Hg, Pb, Ni, and Cd; negative for Cu, Zn, and Fe; and no correlation for Mn and Cr.

Comparative study of three sequential extraction procedures for metals in marine sediments

Abstract In the last few decades, several sequential extraction procedures have been developed, making it difficult to compare the results obtained by the different methods. Three extraction techniques (Tessier et al. 1979; Kersten and Forstner 1986; and the Bureau Communautaire de Reference (BCR)) were applied to four marine sediments with different trace metal contents. To be able to compare the results obtained by methods with different numbers of fractions (6 for Kersten and Forstner, 5 for Tessier, and 4 for BCR), the fractions of each method were grouped into four “equivalents” (acid soluble, reducible, oxidable, and residual). The results obtained for Cu, Pb, Zn, Cr, Mn, and Fe partitioning show that the metal distribution obtained with the three procedures is significantly different. The Tessier procedure gives the lowest concentration values in the acid soluble and oxidable fractions for most of the metals studied. On the other hand, this method usually gave the highest values for the residual fraction. Finally, in the reducible fraction, the Kersten and Forstner procedure showed the highest values for Cu, Cr, and Fe, and the Tessier procedure gave the highest values for Zn, Mn, and Pb.

Heavy metals in fish (Solea vulgaris, Anguilla anguilla and Liza aurata) from salt marshes on the southern Atlantic coast of Spain

Comparisons were made of metal concentrations in water and sediment with those in the muscle and livers of three species of fish caught in four seawater reservoirs (two in the Odiel estuary and two in the Bay of Cádiz). The concentrations of a large number of metals in the water, sediment and fish were higher in the Odiel reservoirs than in those in Cádiz. We found high metal-enrichment factors in the livers as compared to muscle (over 100 for Fe and Cu and around 5 for Zn, Ni, Cd and Pb). The three fish species showed differences in metal content. For example, eels accumulated more metals in muscle and grey mullet in the liver. The metal levels found in muscle in the three species were below the legal limits for human consumption, although Cu in the liver was above the limit in the three species taken from the Odiel reservoirs, and Zn levels in liver were over the maximum in eels from one of the Odiel marshes. Significant correlations (p<0.05) were obtained for the levels of numerous metals in water, sediment and fish.

Partitioning of metals in sediments from the Odiel River (Spain)

The Odiel River runs through an area known as the Iberian pyrite belt in the province of Huelva in the southwestern corner of the Iberian Peninsula. Its waters are acidic and contain large amounts of heavy metals from erosion and mining activity. In addition, the Odiel River estuary is one of the most industrialized areas in southern Spain and, consequently, receives the discharge of industrial and urban waste. Seventeen sediment samples from the Odiel and its main tributaries were analyzed for this study. The chemical partitioning of metals (Cu, Zn, Cd, Pb, Fe, Ni, Cr and Co) in each sample was determined in four fractions (acid-soluble, reducible, oxidizable and residual). The total content of each of the metals was also determined. The results showed high concentrations of Fe, Cu, Zn, Pb and Cd, undoubtedly as a result of contamination from the mining and industrial activity mentioned above. However, the concentrations of the other metals analyzed were low since there are no sources of pollution by them in the Odiel River. Based on the chemical distribution of metals, we found that Cd, Zn and Cu are the most mobile metals (i.e., metals that can pass easily into the water under changing environmental conditions). Cd is the metal that showed the highest percentages in the acid-soluble fraction (the most labile) and the lowest in the residual fraction. However, Pb, Fe, Cr and Ni are present in the greatest percentages in the residual fraction, which implies that these metals are strongly linked to the sediments.

Speciation of heavy metals in sediments from salt marshes on the southern Atlantic coast of Spain

A six-step sequential extraction technique was used to determine the chemical association of heavy metals (Pb, Cd, Cu, Fe, Mn, Zn, Cr, Ni) with major sedimentary phases (exchangeable ions, carbonates, manganese oxides, iron oxides, sulfides and organic matter and residual minerals) in samples from salt marshes on the southern Atlantic coast of Spain (Odiel and Bay of Cadiz Salt Marshes). The total metal content was determined as well. In the Bay of Cadiz Salt Marsh sediments, all the metals, except Mn and Pb, were extracted from the residual fraction at a percentage greater than 50%. In the Odiel Salt Marsh, however, only Cr surpasses 50%. The metals that are most easily extractable in the samples analysed were Mn, Zn, Pb and Cd.

Adsorptive features of acid-treated olive stones for drin pesticides: equilibrium, kinetic and thermodynamic modeling studies.

The adsorption behavior of drin pesticides from aqueous solution onto acid treated olive stones (ATOS) was investigated using stir bar sorptive extraction and gas chromatography coupled with mass spectroscopy. The effects of sorbent particle size, adsorbent dose, contact time, concentration of pesticide solution and temperature on the adsorption processes were systematically studied in batch shaking sorption experiments. Maximum removal efficiency (94.8%) was reached for aldrin (0.5 mg L(-1)) using the fraction 63-100 microm of ATOS (solid/liquid ratio: 1 g L(-1)). Experimental data were modeled by Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherms. The Freundlich isotherm model (R(2)=0.98-0.99) fitted the equilibrium data better than the Langmuir and D-R isotherm models, with low sum of error values (SE=1.4-9.2%). The mean adsorption free energy derived from the D-R isotherm model (R(2)=0.95-0.99) showed that the adsorption of drin pesticides was taken place by weak physical forces, such as van der Waals forces and hydrogen bonding. The calculated thermodynamic parameters, DeltaH, DeltaS and DeltaG prove that drin pesticides adsorption on ATOS was feasible, spontaneous and exothermic under examined conditions. The pseudo first order, pseudo second order kinetic and the intra-particle diffusion models were used to describe the kinetic data and rate constants were evaluated.

Drin pesticides removal from aqueous solutions using acid-treated date stones

This work describes the potential applicability of chemically and thermally treated date stones for removing drin pesticides (aldrin, dieldrin and endrin) from aqueous solutions. The effect of several parameters, such as sorbent particle size, adsorbent dose, shaking speed, shaking time, concentration of pesticide solution and temperature, was evaluated by batch experiments. Pesticide determination was carried out using stir bar sorptive extraction and gas chromatography coupled with mass spectroscopy. Maximum removal efficiency (93%) was reached using 0.1 g of acid-treated date stones (ATDS) (63-100 microm) and 100 mL of aldrin (0.5 mg L(-1)). The removal efficiency of drin pesticides decreased in the order of aldrin, dieldrin and endrin, and decreased as the temperature rose. Adsorption data were processed according to various kinetic models. Lagergren and Morris-Weber equations were applied to fit the kinetic results. The second order model was the most suitable on the whole, and intra-particle diffusion was found to be the rate-controlling the adsorption process. According to adsorption kinetic data, 3.5h were considered as the equilibrium time for determining adsorption isotherms. Adsorption data were analyzed by the Langmuir, Freundlich and Dubinin-Radushkevich adsorption approaches. Experimental results showed that the Freundlich isotherm model best described the adsorption process. In addition, thermodynamic parameters such as DeltaH, DeltaS and DeltaG were calculated. Negative values of DeltaH and DeltaG indicate the exothermic and spontaneous nature of pesticide adsorption on ATDS.

Validation of stir bar sorptive extraction for the determination of 24 priority substances from the European Water Framework Directive in estuarine and sea water.

This paper describes the validation of a method for the determination of 24 priority substances from the European Framework Directive in estuarine and sea water using the new extraction technique known as stir bar sorptive extraction (SBSE), followed by thermal desorption using capillary gas chromatography-mass spectrometry. We studied linearity, detection and quantitation limits and accuracy (which includes determination of trueness and precision). Using the lack-of-fit method we tested linearity in the 0-200ngL(-1) range for all the priority substances. The detection and quantification limits were less than 5 and 10ngL(-1), respectively, for most of the compounds studied. Precision was assessed by variance analysis (ANOVA) and relative standard values of less than 10% were obtained for repeatability and less than 15% for intermediate precision. The recovery percentages in spiked estuarine and sea water were close to 100%. Finally, for quality control of the method (stability of precision and accuracy through time), we developed a method for calculating Shewhart control charts based on the information obtained in the validation process.

Trace metal bioavailability in the waters of two different habitats in Spain: Huelva estuary and Algeciras Bay.

The barnacle Balanus amphitrite has been used as a biomonitor of metals (As, Cd, Cu, Mn, Hg, Ni, and Zn) in two different littoral habitats in southern Spain: Huelva estuary and Algeciras Bay. Water samples were collected from the same sites as the barnacles to assess metal concentrations and to gain additional information on the environmental conditions. The results clearly showed differences between these two marine habitats. Analysis of variance (ANOVA) showed significant geographic differences in the bioavailability of metals to the barnacles, as reflected in the concentrations of accumulated metals. There was a significant correlation (p<0.05) between the Cu, Mn, Ni, and Zn concentrations found in B. amphitrite and in the dissolved fraction in water from the two areas studied.

Trace metals in sediments from the "Ría de Huelva"

The Ria de Huelva is an estuarine zone into which flow the Odiel and Tinto rivers, polluted by trace metals. Total contents of Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Pb, Cd and Hg were determined in the < 630 and < 63 pm fractions of bed sediments. Total trace metal contents in the coarsest fraction are lower Ihan in the finest, although both are highly correlaled for mosl of the metals, allowing an easy grain size elTect correclIon. Total concentrations of Cu, Zn, As, Pb and Hg are very high, having enrichmenl faclor indexes ranging from 35-111. Important proportions of these are in easily soluble and reducible physico-chemical forms, which are readily available for living organisms.