Trace metals speciation in coastal particulate matter for marine environmental studies in Antarctica.

Solid speciation of some trace metals (Pb, Cd, Fe, Mn, Cu) having environmental relevance was studied in coastal particulate sampled during the Austral Spring 2000/2001. A nearshore station situated in the Gerlache Inlet of Terra Nova Bay (Ross Sea, Antarctica) was sampled from November to February. Samples were collected using the in situ filtration system FIS500, equipped with polycarbonate membrane filters having different pore sizes (10 microm, 2 microm and 0.4 microm) for the size fraction analysis of particles. The total concentration of metals was determined both in dissolved and particulate fractions, while speciation was determined on particulate by applying a sequential extraction procedure. Concerning the surface and sub-surface layers, it has been observed that concentration of elements is mainly affected by the dynamic of the pack ice melting and by phytoplankton activity. The solid speciation in November and December is similar for all the studied elements, while some differences can be noted in February, when the pack has completely melted and phytoplankton bloom occurs. With the exception of iron, during this sampling period the quantity of metal associated to the labile fraction increases.

Determination of porphyrins and metalloporphyrins using liquid chromatography-diode array detection and mass spectrometry.

A HPLC procedure has been optimized and successfully applied to porphyrins of environmental interest, such as etio and octaethylporphyrins and their VO and Ni compounds. The use of UV-Vis diode array allowed the detection of the analytes within the 5-15 ng/ml range. In order to achieve greater specificity and some structural information, the coupling of liquid chromatography with mass spectrometry was investigated, and the particle beam interface conditions were optimized. Electron impact (EI) spectra, comparable to those reported in the literature were obtained. The entire procedure has been applied to a real marine sediment, previously spiked with porphyrins to resemble oil-contaminated samples. The results pointed out that the method is suitable for such levels of analytes (5-10 microg/ml), allowing their identification and quantification with no need for purification steps.

Evaluation and comparison of two selective extraction procedures for heavy metal speciation in sediments.

Two sequential extraction procedures (the former proposed by the Standard, Measurements and Testing-SM&T-program of European Union and the latter derived from those of Tessier and Forstner with various modifications) have been compared, by analyzing a reference material (CRM 601) certified for the content of heavy metals in the three solutions resulting from the SM&T procedure. Scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDX) was used to evaluate the composition of the residues after various extractions. Reliable results, both in terms of precision and accuracy, were obtained for the first two steps of the SM&T scheme. As regards the third step, because it was modified during this work, a direct comparison of our results with those certified is not possible. SEM analysis confirmed that the scheme previously used in the laboratory was more aggressive compared to the SM&T procedure, which has also the advantage that the only CRM available for metal partitioning in sediments is certified using this method.

Determination of trace amounts of vanadyl porphyrin in marine mussel tissues by high-performance liquid chromatography with both ultraviolet/visible and inductively coupled plasma atomic emission spectrometric detection.

An HPLC method with UV/VIS and ICP-AES detection is described for the determination of vanadyl porphyrins extracted from biological samples. A detection limit of 50 ng of vanadium was obtained. The method was used to determine these compounds following their extraction from tissues of mussels treated in laboratory experiments and collected during a 'Mussel Watch Programme'. This allowed some conclusions about vanadium speciation in marine organisms to be made. In the tissues of mussels, collected at several sites of the monitored area, which showed high vanadium concentrations, it was possible to establish the presence of this metal in the form of organometallic compounds.

Spectroscopic evaluation of interactions among trace elements and biogenic carbonates in the marine environment.

The interactions between trace elements and biogenic carbonates (marine mussel shells) in aqueous media were evaluated. The behaviour of Mn, Cu, Co, and Cd was investigated using spectrometric techniques (electrothermal atomic absorption, inductively coupled plasma atomic emission and electron paramagnetic resonance). The results obtained show that the metals considered do not form a distinct precipitated phase on the shell surfaces, but that they interact with the CaCO3. This study aimed to provide more information on the mechanisms involved in the storage of trace elements by the shells of marine bivalves. This would allow the use of mussel shells as an alternative to soft tissues for trace metal analyses in biological monitoring programmes.

The speciation of trace amounts of organometallics in marine organisms by gel-permeation high-pressure liquid chromatography with PAR derivatization.

A high-pressure liquid chromatograph equipped with an off-column calorimetric reactor was used for the determination of metallorganic compounds such as metallothioneins. The stainless-steel gel-permeation column used was first tested with ultraviolet detection of a standard protein mixture. The metallothioneins were determined by absorbance measurements at 520 nm after an off-column reaction of the metal-containing eluates with a buffered 4-(2-pyridylazo)resorcinol (PAR) solution. The eluates were also tested by flame and electrothermal atomic-absorption spectrometry; a correlation between AAS and ICP results and the peak areas of the calorimetric detection was also made. A zinc-inhibiting reagent was also added to the PAR solution in order to find the calorimetric error due to the presence of other metals such as copper or cadmium.

Seasonal variation of thallium, lead, and chromium concentrations in airborne particulate matter collected in an urban area.

In November 1985 a research program started, with the aim to evaluate seasonal variations in the concentrations of organic and inorganic pollutants in the atmosphere of Genoa. The program provided for the collection of samples of airborne particulate in five different areas with distinct urban characteristics. First results for chromium, lead, and thallium concentrations in an industrial and in an urban area are reported. Lead showed the highest concentration at both locations (geometric mean: 1.037 and 0.476 microgram/m3, respectively) and appeared to be little affected by seasonal variation. Private traffic was confirmed as the main source of this pollutant. Chromium and thallium geometric mean concentrations were 0.006 and 0.014 microgram/m3 in site A and 0.017 and 0.015 microgram/m3 in site B, respectively. In the urban location a good negative linear correlation was found between chromium and thallium concentration and mean ambient temperature; the domestic heating plants were suspected as important emission sources of these two compounds.

Reduction of hexavalent chromium by mitochondria: methodological implications and possible mechanisms.

The reduction of hexavalent chromium by rat liver mitochondria was studied under various experimental conditions. The occurrence of possible artifacts arising from inadequate methods for Cr(VI) detection was also tested. Erroneous results due to the presence of NAD(P)H (above 0.1 mM) could be demonstrated when the diphenylcarbazide method is employed. Modifications of this colorimetric procedure are proposed, in order to minimize artifacts occurring when Cr(VI) is detected in NAD(P)H-added mixtures. Although no interfering substances that can affect colorimetric methods are normally present in mitochondrial preparations, some methodological precautions are recommended. Mitochondria can reduce hexavalent chromium using either succinate or glutamate as electron donors. The succinate-supported reduction of Cr(VI) is active especially in the presence of ADP or an uncoupler, while reduction induced by glutamate occurs only in the presence of respiratory-chain inhibitors. In mitochondria supplemented by NAD-linked or FAD-linked substrates, different mechanisms in Cr(VI) reduction can therefore take place.

Ion-exchange separation and atomic-absorption determination of fifteen major, minor and trace elements in silicates.

A scheme of ion-exchange separation of fifteen elements (major, minor and trace) determined mainly by atomic-absorption spectrophotometry (Ti by colorimetry) is applied to rock, mineral and ceramic analysis. Mn, Cu, Co, Fe and Zn are separated on an anion-exchanger and Li, Na, K, Mg, Ca, Sr, Ti, Al, Ni and Ba on a cation-exchanger. The method has been tested by analysis of a synthetic mixture of the fifteen ions in the ratios in common rock samples, and of various international standards (100-mg samples).

Organic acid solutions in the chromatography of inorganic ions-IV: cation-exchange of Mn(II), Cd(II), Co(II), Ni(II), Cu(II), Al(III) and Fe(III) in tartrate media.

The cation-exchange behaviour of Mn(II), Cd(II), Co(II), Ni(II), Cu(II), Al(III) and Fe(III), in tartaric acid media was studied. Separations of Fe(III), Cu(II), Ni(II), Co(II), Cd(II) and Mn(II) on Dowex 50W X8 have been achieved.

Determination of trace amounts of barium in silicate rocks and minerals by ion-exchange Chromatography and atomic-absorption spectrophotometry.

Trace amounts of barium are determined in the standard silicate rocks and minerals, W-1, AGV-1, BCR-1, DTS-1, GSP-1, G-2 of the U.S. Geological Survey and BR, GA, GH, GR, UB-N, DR-N, BX-N, DT-N, VS-N, FK-N, GS-N of the Centre de Recherche Petrographique et Geochimique de Nancy and the Association Nationale de la Recherche Technique. After an ion-exchange separation, the analyses are carried out by atomic-absorption spectrophotometry. The separation is performed to eliminate interferences due to matrix effects.