Long term geochemical variation of brines derived from a major phosphogypsum pond of SW Europe.

The chemical evolution of brines resulting from an inactive phosphogypsum pond derived of fertilizer industry located in Huelva (Spain, SW Europe) has been studied based on a weekly sampling from 2014 to 2017. Long-range time variation of metals and ions concentrations in brines are expected to depend on environmental parameters such as rainfall and evaporation. The results show that brines are enriched in F- (1.7-2.0 g/l), Cl- (13-24 g/l), SO42- (7.2-9.3 g/l), V (70-128 mg/l) and U (55-98 mg/l). A great variation of chemical concentrations has been found, due to dilution, recharge and evaporation processes. Most of the elements show peak concentrations in summer, coinciding with the lowest pH values (<1), high conductivity (>133 mS/cm), and high evaporation rates as expected. Nonetheless, F- shows an opposite behaviour, varying its concentrations between 0.9 g/l in summer and 3.7 g/l in the rainy season. According to the results, a future restoration plan for PG ponds should include the removal of brines and layered salts during summer in order to avoid the annual generation of brines and their impact on the environment.

Stratification of Metal and Sulphate Loads in Acid Mine Drainage Receiving Water Dams - Variables Regionalization by Cluster Analysis.

The Sancho Reservoir (Iberian Pyrite Belt, SW Spain) is nourished by the waters of the river Meca, which is affected by acid mine drainage (AMD) processes from the abandoned Tharsis mine. The aim of the present work is to study the hydrochemical variations in this reservoir, in order to define potential stratification processes in metal load and sulphates. A stratified sampling from the surface, with one meter deep intervals to the bottom of the dam, was performed. The results show a clear stratification of temperature, pH, electric conductivity, dissolved oxygen, metal and sulphate loads associated with depth. There is an increase of metal loads at the bottom of the reservoir, though previous studies only detect iron. The proximity between pH and aluminium suggests that water chemistry is strongly influenced by aluminium precipitation processes. This indicates the buffer effect that aluminium exercises, which precipitates as amorphous or low crystalline phases, introducing hydrogen ions to the system, while alkalinity input tends to raise pH.

Hydrogen fluoride concentrations in ambient air of an urban area based on the emissions of a major phosphogypsum deposit (SW, Europe).

Hydrogen fluoride (HF) is one of the most toxic gaseous compounds in air, the primary anthropogenic source of which is industrial activity, specifically fertilizer and waste. HF concentrations in an urban area (Huelva, SW Spain) related to a nearby major phosphogypsum (PG) deposit were measured by passive sampling during summer and winter months from 2014 to 2017 and high-resolution sampling during 2017 and 2017-2018 using an HF analyser. An HF geochemical anomaly was found in the PG pond with average concentrations of up to 19.1 µg/m3, and concentrations of up to 1.6 µg/m3 were exhibited in the nearest urban area. The concentrations were associated with the HF emissions from the PG deposit. Emission factors were calculated by field and laboratory experiments, and the brines exhibited the highest emission factor (2.7 kg/ha day). Several impacts of HF (>0.1 µg/m3) in the city were recorded throughout the year, occurring at noon in the summer and during fog events in the winter. Consequently, the PG system should be restored to protect the population living in Huelva from the impacts of HF emission.

Organotin contamination in the Atlantic Ocean off the Iberian Peninsula in relation to shipping.

Imposex in female snails, a bioindicator of TBT contamination, and the presence of organotins in snails' tissue and sediments were studied at nine sites off the western Iberian Peninsula. The study was part of a European project (acronym HIC-TBT) co-financed by the EU-LIFE programme, intending to investigate and communicate the impact of organotins from ships in marine ecosystems. Snails and sediments were sampled during two cruises in May/June 1999 and in January 2000 in areas of high, intermediate and low-shipping density. Imposex was found in female snails from several sampling sites, some of which had an imposex incidence of 100%. Differences in sensitivity were found between species; hence comparison of imposex levels between locations where different species were collected was not straightforward. Total organotin concentrations in sediments (sum of butyl and phenyltin compounds) ranged from 21 to 185 ng Sn g(-1) with higher values for most sites sampled in the vicinity of shipping lanes. Organotin concentration in snails' tissue ranged from <5 to 196 ng Sn g(-1), which are similar to those found in snails from other offshore areas contaminated by TBT. Overall, these results give further support to the recent ban on the use of organotin based antifouling paints to all ship size.

Arsenic species in atmospheric particulate matter as tracer of the air quality of Doñana Natural Park (SW Spain).

Sampling and chemical analyses, including major compounds and trace elements, of atmospheric particulate matter (PM10 and PM2.5) have been performed during 2006-2007 in a regional background monitoring station located within the Doñana Natural Park (SW of Spain). This region is strategic for air quality and climate change studies, representing a meeting place of the European and African continents, and the Atlantic Ocean and Mediterranean Sea. The present study based on meteorological parameters demonstrated long-range transport and impact of industrial plumes on the Doñana Natural. Inorganic arsenic species (arsenate and arsenite) have been analyzed in particulate matter (PM) to characterize the impact of near Cu-smelter plumes and demonstrated the long-range transport of industrial pollutants. As(V) is the main specie of As and varies between 95% and 98% of total As in PM10 and 96-97% in PM2.5. The As(V)/As(III) ratio measured in emission plumes of a Cu-smelter are similar to the ratio found in the Doñana Natural Park. The application of Positive Matrix Factorization (PMF) to atmospheric particulate matter estimated the contributions and chemical profiles of natural and anthropogenic sources impacting the Natural Park, demonstrating the industrial origin of the As and other toxic elements in the air.

Sample treatment in chromatography-based speciation of organometallic pollutants.

Speciation analysis is nowadays performed routinely in many laboratories to control the quality of the environment, food and health. Chemical speciation analyses generally include the study of different oxidation state of elements or individual organometallic compounds. The determination of the different chemical forms of elements is still an analytical challenge, since they are often unstable and concentrations in different matrices of interest are in the microg l(-1) or even in the ng l(-1) range (e.g., estuarine waters) or ng g(-1) in sediments and biological tissues. For this reason, sensitive and selective analytical atomic techniques are being used as available detectors for speciation, generally coupled with chromatography for the time-resolved introduction of analytes into the atomic spectrometer. The complexity of these instrumental couplings has a straightforward consequence on the duration of the analysis, but sample preparation to separate and transfer the chemical species present in the sample into a solution to be accepted readily by a chromatographic column is the more critical step of total analysis, and demands considerable operator skills and time cost. Traditionally, liquid-liquid extraction has been employed for sample treatment with serious disadvantages, such as consumption, disposal and long-term exposure to organic solvent. In addition, they are usually cumbersome and time-consuming. Therefore, the introduction of new reagents such as sodium tetraethylborate for the simultaneous derivatization of several elements has been proposed. Other possibilities are based in the implementation of techniques for efficient and accelerated isolation of species from the sample matrix. This is the case for microwave-assisted extraction, solid-phase extraction and microextraction, supercritical fluid extraction or pressurized liquid extraction, which offer new possibilities in species treatment, and the advantages of a drastic reduction of the extraction time and the embodiment into on-line flow analysis systems. This new generation of treatment techniques constitutes a good choice as fast extraction methods for feasible species-selective analysis of organometallic compounds under the picogram level, that can be used for national regulatory agencies, governmental and industrial quality control laboratories, and consequently, for manufacturers of analytical instrumentation.

Column-switching system for selenium speciation by coupling reversed-phase and ion-exchange high-performance liquid chromatography with microwave-assisted digestion-hydride generation-atomic fluorescence spectrometry.

Speciation of selenocysteine (SeCys), selenomethionine (SeMet), selenoethionine (SeET), selenite (Se(IV)) and selenate (Se(VI)) has been accomplished using high-performance liquid chromatography, with the aid of an anion exchange column and a reversed-phase column, both connected through a six-port switching valve. On-line microwave-assisted digestion and hydride generation steps were performed prior to the atomic fluorescence detection. The elution of the seleno amino acids was accomplished in the reversed-phased column using water as mobile phase. Selenite and selenate were separated in the anion exchange column, using gradient elution with an acetate buffer. The separation of the five selenium compounds took place in 15 min. The detection limits obtained ranged between 0.6 and 0.9 microg l(-1). Values of r>0.998 were obtained for linear fit graphs. A commercial available urine sample was analyzed, in which SeCys and Se(IV) were quantified.

High-performance liquid chromatographic determination of primary amines in aqueous solutions after extraction and derivatization with 2,2-diphenyl-1-oxa-3-oxonia-2-boratanaphthalene (DOOB).

Aqueous solutions of tryptamine, tyramine and ethanolamine are extracted and derivatizated to azomethine chelates using a solution of DOOB in diethyl ether. The extraction takes about 2 h. Diisopropyl ether and toluol have also been tested as extractants. The separation of the azomethine chelates is realized by a gradient program on a Si 60 column using a mixture of n-heptane/tert-butyl methyl ether. UV detection is carried out at 280 nm. The concentration of these three amines has been determined in a Chianti wine sample.

Comparison of the feasibility of three extraction procedures for trace metal partitioning in sediments from south-west Spain.

The feasibility of three sequential extraction schemes (a modification of the Tessier procedure, the scheme proposed by Meguellati and the protocol designed by BCR (now called the Standards, Measurements and Testing Programme, M&T) have been compared to study the distribution of As, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb and Zn in sediment samples. The comparison has been performed by analyzing Certified Reference Material (CRM-601), a test material (S-12) and seven sediments from the Odiel Marshes Natural Park (located at the Atlantic coast of southern Spain). Samples were classified as sandy (with low iron oxide and organic matter contents) and clay-silty (with high iron oxide and organic matter contents) sediments. A higher metal mobility, especially under reducing conditions, was more properly assessed using the modified Tessier scheme compared to both the BCR and Meguellati procedures, these two later presenting comparative results for the reducible and residual phases. Significant Hg losses were found using the BCR procedure but the quantification of the acid phase for Cd, Cr and Ni was more reliable than that obtained with the modified Tessier and Meguellati schemes.

Determination of selenomethionine and seleno-methyl-selenocysteine in biota by ultrasonic-assisted enzymatic digestion and multi-shot stir bar sorptive extraction-thermal desorption-gas chromatography-mass spectrometry.

A method based on stir bar sorptive extraction (SBSE) and thermal desorption (TD)-gas chromatography-mass spectrometry (GC-MS) has been optimized for the determination of seleno-methyl-selenocysteine (SeMetSeCys) and selenomethionine (SeMet) in biota samples. Aliquots of freeze-dried tissue, a mixture of protease XIV-lipase and water were sonicated for 2min. After extraction, the extract was separated by centrifugation and subjected to derivatization and SBSE-TD-GC-MS. The parameters affecting derivatization, absorption and desorption steps were investigated. The optimized conditions consist of a derivatization with 40µL of ethyl chloroformate (ECF) in 400µL of a water:ethanol:pyridine (60:32:8) mixture, followed by dilution to 1.5mL of 70g NaClL(-1) in water at neutral pH and an extraction step using 10mm×1mm PDMS stir bar, stirring at 800rpm for 20min at room temperature (23±1°C). Three stir bars were used for the extraction of three different aliquots of the same sample and then placed in a single glass desorption liner and simultaneously desorbed for GC-MS analysis. The desorption step required the following conditions: 300°C (desorption temperature), 6min (desorption time), 50mLmin(-1) (vent flow) and -5°C (cryotrapping temperature). The method provided precise (8.1%) and accurate results in the mgSekg(-1) range (using the selected-ion monitoring-SIM mode) against certified reference material SELM-1 yeast, with recoveries higher than 80% for spiked algae and clams samples.

Health implications of the distribution of arsenic species in airborne particulate matter.

Airborne particle samples were taken between 2001 and 2008 at an urban site (Huelva) in southwestern Spain. Arsenic was found in the samples due to the presence of a near-by copper smelter, sometimes at concentrations above the target value of 6 ng m(-3) proposed by EU regulations (annual means from 4.6 to 10.4 ng As m(-3) in PM10, and 3.0 to 9.1 ng As m(-3) in PM2.5). The results obtained by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) showed that arsenic accumulates preferentially (ca. 70-80%) in the particles with smaller diameter (PM2.5 versus PM10), representing a threat to human health due to the higher capacity of the finer particles to enter the organism through the respiratory system. Moreover, the toxicity of the inorganic arsenic species depends also on the oxidation state, As(III) being more toxic that As(V). The speciation analysis performed with High Performance Liquid Chromatography-Hydride Generation- Atomic Fluorescence Spectrometry (HPLC-HG-AFS) with samples collected between 2006 and 2008, showed that As(V) represented the main arsenic species, but As(III) was also found at significant concentration, representing a 5-10% of the total arsenic content. The results also indicate that the more toxic As(III) tends to concentrate preferentially in the finer fraction PM2.5 in comparison with As(V), thus representing an added health risk for the local population.

Speciation of antimony in airborne particulate matter using ultrasound probe fast extraction and analysis by HPLC-HG-AFS.

A fast extraction procedure has been developed for Sb(III) and Sb(V) oxoanions speciation in airborne particulate matter samples. Different extraction media (diammonium tartrate, hidroxilammonium clorhidrate, citric acid+ascorbic acid, phosphoric acid and citrate solutions) were tried, with assistance of an ultrasonic probe. The operation power and time of extraction were also optimized. The higher extraction recoveries were obtained with a 100 mmol L(-1) hidroxilammonium clorhidrate aqueous solution assisted by the ultrasound probe operated at 50 W during 3 min. The extracts were analyzed by HPLC-HG-AFS. The chromatographic separation of Sb(III) and Sb(V) was also optimized using diammonium tartrate and phthalic acid as mobile phases. The separation of both Sb species was performed in less than 3 min under isocratic conditions, using a 200 mmol L(-1) diammonium tartrate solution. The proposed extraction procedure and the HPLC-HG-AFS instrumental coupling have been successfully applied to airborne particulate matter samples, with high Sb content, collected in heavy traffic streets from Buenos Aires (Argentina). The results showed the presence of both Sb species at similar concentrations in the ng m(-3) level. The extraction yield was higher than 90% for all the analyzed samples.

New preservation method for inorganic arsenic speciation in acid mine drainage samples.

A new preservation method has been proposed for the speciation of As(III) and As(V) in acid mine drainage (AMD) samples, characterised by low pH and high metallic content. Samples were taken from a polymetallic sulphides mining area in the province of Huelva (SW Spain), under exploitation until the 1960s for its Cu, Pb and Zn sulphides. The abandoned mine works and the numerous waste rocks heaps produce AMD with high As content, an aqueous pollution source for the nearby streams. Short-term (from few hours to 1 week) preservation of the two inorganic arsenic species was studied, trying different containers (polyethylene, glass), presence or absence of light, temperatures (ambient, refrigerated, frozen), preserving agents and procedures (EDTA, HCl or AcH acids, cation-exchange resin). The speciation results obtained by liquid chromatography-hydride generation-atomic fluorescence spectrometry (HPLC-HG-AFS) indicated a rapid conversion of the samples with most of the preservation procedures reported in the literature after 3h after sample collection. A promising method for arsenic preservation has been developed in this work, which maintains the arsenic species distribution in the original samples for a longer time. It consists in the use of opaque glass containers, acidification of the samples with HCl and in situ cleanup with cationic exchange resin, which allowed to preserve the samples for As speciation for at least 48 h.

Characterisation of sequential leachate discharges of mining waste rock dumps in the Tinto and Odiel rivers.

Mining waste rock dumps (WRDs) are potential sources of pollution, which after rainfall produce leachate discharges, loaded with acid mining drainage (AMD). The discharges generally occur in two phases: initial rapid leaching over a period of 1-7 days, followed by a period of variable duration during which leaching decelerates. The relative preponderance of each phase depends on the characteristics of the WRD, including its antecedent hydrological condition, and the temporal pattern and amount of rainfall.

Determination of an arsenosugar in oyster extracts by liquid chromatography-electrospray mass spectrometry and liquid chromatography-ultraviolet photo-oxidation-hydride generation atomic fluorescence spectrometry.

HPLC-UV-HG-AFS analysis of aqueous extracts of oysters (Crassostrea gigas) taken from the southwestern Atlantic coast of Spain showed the presence of arsenite, arsenate, dimethylarsinic acid and an unidentified arsenic peak. Subsequent analysis of the oyster samples by LC-electrospray MS and comparison with four standard dimethylarsinoylribosides (arsenosugars), showed that the previously unidentified peak was an arsenosugar (arsenosugar 2). When the arsenosugar in the oyster was quantified using the two detection methods and external calibration with standard arsenosugar, there was a large discrepancy between the two sets of results. The LC-MS analysis was strongly affected by the sample matrix and gave concentrations 50% lower than those obtained by AFS detection. When the method of standard addition was applied to the LC-MS analysis, the results were comparable to the AFS data. The matrix effects were eliminated by subjecting the extract to a clean-up procedure with anion-exchange and gel permeation preparative chromatography before the LC-MS analysis. The arsenosugars gave a small signal without photo-oxidation when they were analysed by HPLC-HG-AFS. Possibly this resulted from partial decomposition of the arsenosugar to dimethylarsinic acid under the acidic conditions employed in the hydride generation step.

A comparison between ICP-MS and AFS detection for arsenic speciation in environmental samples.

Performances of two atomic detectors, Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) and Atomic Fluorescence Spectrometry (AFS) have been compared for arsenic speciation in environmental samples. Instrumental couplings, based on the use of high performance liquid chromatography (HPLC), hydride generation (HG), and the two atomic detectors were used for the speciation of arsenite, arsenate, dimethylarsinic acid and monomethylarsonic acid. Optionally, arsenobetaine was also determined using on-line ultraviolet (UV) photooxidation. The detection limits ranging from 0.1 to 0.3 mug l(-1) (as As) and the precision >10% RSD obtained with HPLC-(UV)-HG-AFS were comparable with those obtained with HPLC-(UV)-HG-ICP-MS. Both instrumental coupling were applied to the NRCC-TORT-1 and several environmental samples, such as seawater, freshwater, sediments, bivalves and bird eggs, taken from two areas with different degrees of pollution. No influence of the sample matrix was observed on the results using external calibration and standard additions methods, for both coupled techniques.

Selectivity assessment of a sequential extraction procedure for metal mobility characterization using model phases.

This study considers the selectivity of the extractants used in a sequential extraction scheme for metals mobility assessment by analyzing individual mineral phases previously coprecipitated or sorbed with trace metals. The scheme evaluated was a modification of the Tessier et al. [A. Tessier, P.G.C. Campbell, M. Bisson, Anal. Chem. 51 (1979) 844] sequential procedure proposed by the authors. The phases studied were calcite, amorphous iron oxide, hausmannite, humic acid, kaolinite and illite. Selective extractions were obtained for As, Cr, Cu, Ni, Pb and Zn in metal-coprecipitated phases whereas NH(2)OH-HCl was not selective for the extraction of Hg and Cd coprecipitated in hausmannite and amorphous iron oxide, respectively. Otherwise, Cd, Hg, Ni and Zn sorbed on the different phases were released with MgCl(2) and NaOAc/HOAc, but stronger reagents were needed to release As, Cr, Cu and Pb.