José Morillo

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.

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.

Potential Mobility of Metals in Polluted Coastal Sediments in Two Bays of Southern Spain

Abstract Surface sediments from Cadiz and Algeciras Bays (southern Spain) were analysed by a sequential procedure for Cu, Zn, Cd, Pb, Fe, Ni, Cr, and Mn to determine their distribution among four geochemical phases (acid-soluble, reducible, oxidisable, and residual). The total metal content was also determined. The results showed that large amounts of metal accumulate in the interior of Cadiz Bay, whereas in Algeciras Bay, the highest levels of metal are found near the city of Algeciras and an area of major industrial activity. A comparison of metal levels with the sediment quality guidelines suggested by Long et al. (1995) showed areas in both bays in which pollution is sufficient to have noxious effects on marine organisms. Chemical partitioning of the metals revealed that Zn and Pb present the highest percentages in the reducible fraction and that Ni, Cr, and Cd are highest in the residual and reducible fractions. Cu shows the greatest proportion in the oxidisable fraction and Mn in the acid-soluble fraction. Fe is found mainly in the residual fraction, probably because it is an element basically of natural origin.

Assessment of heavy metals bioavailability and toxicity toward Vibrio fischeri in sediment of the Huelva estuary.

Relationship between toxicity and bioavailable metals in sediments from the Huelva estuary and its littoral of influence was analyzed. Toxicity was assessed with Microtox® bioassay using a marine luminescent bacterium: Vibrio fischeri. Bioavailable metals were considered as both, acid extractable fraction of BCR procedure and the sum of exchangeable and bound to carbonates fractions of Tessier sequential extraction. A bioavailable metals index was calculated to integrate results in a single figure. Toxicity and bioavailable metals showed a similar pattern. Higher levels were found in the estuary than in the littoral (140 TU/g). In Huelva estuary, highest levels were found in the Tinto estuary (5725 TU/g), followed by the Odiel estuary (5100 TU/g) and the Padre Santo Canal (2500 TU/g). Results in this area were well over than those in nearby estuaries. Furthermore, they are similar to or even higher than those in other polluted sediments around the world. Bioavailable metal index showed a stronger correlation with acid extractable fraction of BCR (R(2) = 0.704) than that for the sum of exchangeable and bound to carbonates fractions of Tessier (R(2) = 0.661). These results suggest that bioavailable metals are an important source of sediment toxicity in the Huelva estuary and its littoral of influence, an area with one of the highest mortality risks of Spain.

Heavy Metal Fractionation in Sediments from the Tinto River (Spain)

Seventeen sediment samples from the Tinto and its main tributaries were analyzed for this study. For each of these samples, the association of metals (Cu, Zn, Cd, Pb, Fe, Ni, Cr and Co) was determined in four fractions: acid soluble, reducible, oxidizable and residual. The total metal content was also determined. Results showed high mean concentrations of Fe (109,000 mg/kg), Pb (2330 mg/kg), Zn (901 mg/kg), Cu (805 mg/kg), and Cd (2.7 mg/kg) in the sediments studied. However, the mean values found for Co (21 mg/kg), Cr (56 mg/kg) and Ni (17 mg/kg) are comparable to those in unpolluted areas. Heavy metal fractionation of the Tinto River sediments showed that the metals with the greatest mobility (i.e., metals that could pass easily into the water under changing environmental conditions) are Cd and Zn. These are the metals that showed the highest percentages in the first two fractions (the most labile) and the lowest percentages in the residual fraction. However, the percentage of metal present in the fourth fraction (residual) was high for Cr (78%), Ni (71%), and Co (66%), which implies that these metals are strongly linked to the sediments.