Determination of atmospheric iodine species using a system of specifically prepared filters and IDMS

Summary A system was developed which allowed the determination of four different atmospheric iodine species by preparing glass microfibre filters, which were arranged in consecutive order, in a specific way. Particulate iodine was collected by a particle filter, HI and I₂ by a NaOH impregnated filter, HOI was adsorbed on a TBAH impregnated filter and organoiodine was adsorbed on a filter loaded with activated charcoal. These behaviours were checked by extensive model experiments. Two or more filters of the same type were used in series to show the degree of collection of one iodine species. Two European samples, one of continental and one of marine origin, and two Antarctic samples were analysed by this filter system using isotope dilution mass spectrometry (IDMS) for quantification. The distribution pattern for the different iodine species is similar for the two European samples. Organoiodine is found to be the most abundant species whereas in Antarctica the HI/I₂ fraction is up to nearly 50% of the total iodine. The particulate iodine fraction is higher in Europe than in Antarctica, which is due to the low particle concentration in the remote area of Antarctica. The higher HI/I₂ and HOI fractions found at the North Sea compared with the continental sample indicate that the ocean is a primary source of these species. Concentrations in the range of (0.3–3.1) ng I/m³ were analysed for particulate iodine, (0.4–1.3) ng I/m³ for HI/I₂, (0.2–1.8) ng I/m³ for HOI and (0.4–7.6) ng I/m³ for organoiodine. The detection limits varied with the variances of the blank values of the different filters and lay between 0.02 ng I/m³ and 0.24 ng I/m³ using sample volumes of 70 m³ air.     

Antarctic marine sediments as fingerprints of pollution migration

Forty elements in 21 coastal marine sediment samples collected duringthe second Antarctic scientific expedition from 18 different sites of Brekilenarea located at the coast of Antarctica were analysed by instrumental neutronactivation analysis (INAA) to detect eventual pollution. Radio-assay schemesfor three sets of elements after neutron irradiation and cooling were evolvedto avoid matrix effects. Data have been compared with those for sedimentsof various stations at Antarctica and two other regions in different continents.Lower concentration of certain elements in the Antarctic sediments reflectsless environmental exposition. Enrichment factors (EF) were calculated forall the elements using the earth crust as reference matrix, based on elementalvalues by MASON, TAYLOR and WEDEPOHL which show a normal pattern near to unityexcept for Ag and Br. The data obtained could also serve as a reference pointfrom which changes in the global environment can be studied. The quality assuranceof data was performed using standard reference materials (SRMs) of a similarmatrix (IAEA Marine Sediment SD-M/TM and Chinese Marine Sediment GBW 07313).     

Mössbauer Investigation of Characteristic Distribution of Iron Oxides in Sediments from the Antarctica

Sediments from the Admiralty Bay, King George Island, Antarctica, were investigated by ⁵⁷Fe Mössbauer spectroscopy, X-ray diffractometry, and radiometry. Quartz, feldspar, chlorite, calcite, dolomite, mica, kaolinite, hematite and magnetite were identified as constituent minerals in the sediment samples. The phase composition and the iron distribution among the crystallographic sites of iron-bearing minerals (silicates, magnetite and hematite) of samples from different location have been derived from the complex Mössbauer spectra. At different locations sediments had significant characteristic differences in the mineral composition, in the iron distribution among the crystallographic site of silicates, and in the specific radioactivity of Cs radionuclides. These results indicate differences in the rock formation and alteration by the sediments in this maritime part of Antarctica. There is a much higher amount of iron oxides in the sediments from south part of the geological fault across the Admiralty Bay than in the north part. This can be associated with much more alteration in the rocks in the south part compared to the northern one. This finding can contribute to the question of the history of the formation and alteration of volcanic rocks in the border of Antarctica.     

Halocarbons in Aqueous matrices from the Rennick Glacier and the Ross Sea (Antarctica)

Aqueous matrices from Antarctica were analysed for three volatile chlorinated hydrocarbons (VCHCs): tetrachloromethane (CCl₄), trichloroethylene (C₂HCl₃) and tetrachloroethylene (C₂Cl₄). The matrices analysed were snow from Rennick Nèvè and Rennick Glacier sampled during the Italian Expeditions of 1995/96 and 1996/97, respectively, and seawater, pack ice, sea-microlayer, subsuperficial water and freshwater, collected during the Italian Expedition of 1997/98. Extractions from the aqueous matrices were carried out in Antarctica (the laboratories of the Italian Base, Terra Nova Bay). Because of the critical space–time conditions in these laboratories, an extraction procedure was developed, suitable for large volumes of water (10?L), in order to combine the extraction of other classes of organic compounds (polychlorinated biphenyls, polycyclic aromatic hydrocarbons and chlorinated pesticides) with those of our direct interest. The VCHC organic extracts were analysed in Italy by GC-ECD and GC-MS. The analyses confirmed the presence of the three halocarbons in Antarctica in quantities ranging from units to some dozens of nanograms per kilogram. The results were evaluated with respect to the local distribution of these compounds and their diffusion on a global scale.     

Synthesis and biodistribution of the 99mTc nitrido complex with 2-(4-nitro-1H-imidazolyl)ethyl dithiocarbamate (NIET)

Sodium and chlorine measurements were made by instrumental neutron activation analysis (INAA) on stratigraphically dated ice core samples from Byrd Station, Antarctica, for the last three centuries. The time period between 1969 and 1989 showed an enhanced impact on the Antarctic ice sheets from oceans in the form of marine aerosols. A disturbed ocean-atmosphere interface due to El Niño Southern Oscillation (ENSO) events seems to be a candidate for this observation in Antarctica.     

THE MICROPARTICLE CONCENTRATION MEASUREMENT AND ITS CLIMATIC IMPLICATIONS IN AN ICE CORE FROM COAST AREA,ANTARCTICA

The microparticle concentration in an ice core from coast area, East Antarctica, has been measured by a Coulter counter and optic counting. It is proposed in the present paper that the microparticle concentrations in different areas are different, especially from the coast to the inland in Antarctica. After its comparison with microparticle concentrations from other cores, it is also proposed that there is a lag between the coldest climate (i. e. 18 ka B. P.) and the highest microparticle concentration.     

Neutron activation analysis on sediments from Victoria Land,Antarctica: multi-elemental characterization of potential atmospheric dust sources

The elemental composition of 40 samples of mineral sediments collected in Victoria Land, Antarctica, in correspondence of ice-free sites, is presented. Concentration of 36 elements was determined by instrumental neutron activation analysis, INAA. The selection of 6 standard reference materials and the development of a specific analytical procedure allowed to reduce measurements uncertainties and to verify the reproducibility of the results. The decision to analyze sediment samples from Victoria Land ice-free areas is related to recent investigations regarding mineral dust content in the TALos Dome ICE core (159°11′E; 72°49′S, East Antarctica, Victoria Land), in which a coarse local fraction of dust was recognized. The characterization of Antarctic potential source areas of atmospheric mineral dust is the first step to identify the active sources of dust for the Talos Dome area and to reconstruct the atmospheric pathways followed by air masses in this region during different climatic periods. Principal components analysis was used to identify elements and samples correlations; attention was paid specially to rare earth elements (REE) and incompatible/compatible elements (ICE) in respect to iron, which proved to be the most discriminating elemental groups. The analysis of REE and ICE concentration profiles supported evidences of chemical weathering in ice-free areas of Victoria Land, whereas cold and dry climate conditions of the Talos Dome area and in general of East Antarctica.     

Mass spectrometry of humic substances of different origin including those from Antarctica A comparative study

Mass spectra of humic acids (HA) from different sampling sites (Antarctica, Brazil, Czech Republic, Mexico and USA) and origin (plant, soil, peat, and coal derived) were obtained by laser desorption/ionization time of flight mass spectrometry (LDI-TOF MS). Optimisation of the experimental conditions are given as the optimal value of the laser energy at 20–30% higher than the threshold. Under these conditions, reproducible mass spectra of HA samples were obtained. In the mass spectra the majority of the peaks are observed in the m/z region 100–1000 Da. Mass spectra fingerprints of HA were analyzed and, in spite of the differences in their origin, a number of common features and profiles (patterns of peaks) were observed in most of the samples. Very similar structural groups (patterns) of the peaks are present in the m/z range 717–918 Da for HA samples of quite different origins, countries or continents.

The tandem LDI-TOF MS and multivariate statistical tools allowed us to extract and elucidate underlying information contained in the mass spectra of the HA samples under study. Applying principal components and cluster analysis, it was, e.g. demonstrated that most of the Antarctica HA samples show distinguishable differences when compared with humic acids from other continents and of different origin.     

Industrial contaminants in Antarctic biota

A critical review of the levels and patterns of industrial contaminants in biota from Antarctica and the Southern Ocean revealed that concentrations are low with respect to other regions of the world, although in some specimens/species (e.g. leopard seal, some invertebrates) they are occasionally high and comparable to those found in regions with a strong human impact; the highest levels of persistent organic pollutants (POPs) were detected in the vicinity of scientific stations. Bioconcentration prevails at the lower trophic levels of pelagic food webs, while biomagnification can become the main route of contamination at higher levels. In a benthic food web, biomagnification poses a major risk for organisms that accumulate lipids to overwinter, compared to those that accumulate glycogen. Hexachlorobenzene, DDTs and chlordanes showed similar concentrations and patterns in the 1980s-1990s period in organisms from Western and Eastern Antarctica, while the polychlorinated biphenyls time trend was different in a variety of species from the two regions.     

Determination of the spallogenic radionuclides26Al and53Mn in Antarctic meteorites with respect to cosmic ray exposure and terrestrial ages

The spallogenic radionuclides²⁶Al (T=7.18·10⁵ a) and⁵³Mn (T=3.8·10⁶ a) were determined in 11 ordinary chondrites and 7 achondrites from Antarctica by nondestructive coincidence counting techniques and radiochemical neutron activation analysis, respectively. The results are discussed with respect to exposure ages, terrestrial residence times and possible genetic relationships of the meteorites investigated. The high terrestrial ages of some specimens (up to 800 000 years) are of importance for the study of the ice flow in Antarctica.     

Separation and characterization of humic acids from Antarctica by capillary electrophoresis and matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Inclusion complexes of humic acids with cyclodextrins

A new capillary electrophoresis procedure based on micellar electrokinetic capillary chromatography for the separation of humic acids (HAs) isolated from Antarctica soil was developed. The HAs were separated and characterized using a background electrolyte containing 0.09 M borate+0.09 M Tris+0.001 M EDTA (BTE) of pH 8.3, modified with alpha-, beta-, or gamma-cyclodextrins (CDs) and sodium dodecyl sulfate. It was found that from alkaline solution of HAs in the presence of CDs, the HAs are not completely precipitated with a strong acid and a certain part (some fractions) remains soluble. Mass spectrometry shows that HAs contain 15-25 simple low-Mr compounds and several families of compounds with similar structure (m/z approximately 800-1200). Comparison of HA analysis from Antarctica soil with those of soil HAs from the American continent show a high similarity between the samples and confirm several identical compounds and some with very similar structural units.     

Biophysiological changes observed in members of the Italian expeditions to Antarctica

The objective of this study was to investigate whether food consumed by individuals working in Antarctica is adequate and sufficient, from the nutritional viewpoint, to sustain life in extreme environments. Malnutrition can be the cause of both health impairment and reduction in psychological and physiological efficiency. The study involved individuals from two subsequent expeditions in Antarctica, namely, 34 subjects (group A) from the Italian Mario Zucchelli Base (MZB) in October-November 2002 and 30 subjects (group B) from the Italian-French Concordia Station (CS) between November 2003 and January 2004. Each group of volunteers consisted of subjects with a controlled diet as well as of subjects with a free diet. Blood and hair samples were taken just before the expeditions (with the purpose of setting the baseline) and during the last week spent in Antarctica. Samples were then shipped to Italy to be analyzed, while the body composition and the hydration status were measured on the spot by Bio-Impedentiometric Assay (BIA). Anthropometrical measurements were carried out weekly. The data obtained were statistically assessed by using the Student t-test for correlated samples and showed, in all subjects, alterations of the hypothalamic-pituitary-thyroid axis, of blood parameters and of some components of the hair along with some variations of the psychological behaviour. The variations observed can probably be ascribed to environmental conditions and a combination of factors such as isolation, atmospheric conditions and prolonged presence of daylight.     

Biocatalyst CAL-B catalyzed synthesis of modified nucleosides: An overview

Nucleosides are valuable biologically active compounds, which display antitumour and antiviral activities. Various types of bioactive nucleosides are designed to improve their therapeutic efficacy, However this strategy faces the difficult selectivity issues of nucleoside chemistry. Therefore, the goal of this review is to give an idea of the opportunities provided by biocatalyst CAL-B procedures in the preparation of different types of bioactive nucleoside compounds. The function of Candida Antarctica lipase-B (CAL-B) in organic synthesis is reviewed. This enzyme has been found to be a principally efficient and robust lipase catalyzing an unexpected variety of reactions including many different regio- chemo, and diastereo-selective synthesis. Moreover, the structure of Candida Antarctica lipase-B is an example of an enzyme for which its specificity has been predicted based on acylation and deacylation mechanism on substrates.     

Neutron activation analysis of snow and ice in Antarctica

In order minimize the possible contamination during storing and pre-treatment of such pure samples as ice and snow collected in Antarctica, trace elements in experimental tools such as bottles, beakers, tubings and filters were determined by neutron activation analysis. By using well certified tools, ice and snow samples from Antarctica and high mountains in China and in Japan were analyzed. Relative concentrations of volatile elements such as Zn, Cd, As, Sb or Ag to Al or Fe which are major components in the earth crust were found to be 10 to 1000 times higher than in the ordinary soil for the samples from Antarctica and Mt. Naimonanyi in China.     

Distribution of humic substances dissolved and particulated in water column in Ross Sea, Antarctica

Dissolved (DFA) and particulate (PFA) fulvic acids were studied in some areas of the Ross Sea (Antarctica) characterised by different water masses. Our interest was focused on their distribution in the water column. Moreover, their correlation with fluorescence data and structural characterisation in relation to the water masses was also studied. We found that PFA concentration was mainly influenced by the primary production in surface layers and by stratification of water masses along the water column. Conversely, the DFA are less influenced by primary production and by the stratification of the water masses. An early stage of the humification process can be hypothesised for PFA related to DFA as shown by elemental analyses and spectroscopic data. PFA collected in the bottom depths of the water column showed a relationship with age of water mass (the highest concentration was found for the oldest circulating water mass (CDW)). This relationship was not observed for DFA. Moreover, any significant difference in structure was found in the DFA and PFA extracted from samples collected at bottom depths.     

Organic Compounds in Surface and Deep Antarctic Snow

Abstract

Eight surface snow samples taken during the 1987/88, 1988/89 and 1990/91 Italian Antarctic Expeditions and six samples collected at different depths from two dissimilar sites during the 1990/91 Expedition, were analyzed for the non-chlorinated organic content using the GC capillary columns technique and GC-MS. Several biogenic and anthropogenic classes of organic compounds were identified and quantitatively determined. The data obtained give a more complete picture of the pollution level in Antarctica.     

A pilot study on the feasibility of the preparation of a new certified reference material based on the Antarctic Scallop Adamussium Colbecki

As foreseen by the Italian National Programme of Research in Antarctica, a preliminary investigation was performed to ascertain the feasibility of the production of a new Certified Reference Material for trace elements based on the bivalve Adamussium colbecki. The scallops sampled in Antarctica during the 1999–2000 Italian scientific expedition were analyzed by inductively coupled plasma atomic emission spectrometry and high-resolution inductively coupled plasma mass spectrometry for their content in selected trace elements (As, Cd, Cr, Cu, Fe, Hg, Mn, Mo, Ni, V and Zn). The certification campaign will be undertaken on the basis of the findings of this feasibility study in close cooperation with the Institute for Reference Materials and Measurements, Joint Research Centre of the European Commission.     

Instrumental neutron activation analysis of extractable organohalogens in the Antarctic Weddell seal (<Emphasis Type="Italic">Leptonychotes weddelli</Emphasis>)

Instrumental neutron activation analysis (INAA) was performed for measurement of extractable organohalogens (EOX) in blubber samples of Weddell seals (Leptonychotes weddelli) from Antarctica. EOX were detected in all the analyzed samples. The concentration order of EOX was: extractable organochlorine (EOCl)>extractable organobromine (EOBr)>extractable organoiodine (EOI). Their levels increased gradually with aging as with other man-made persistent organic pollutants (POPs) such as PCBs and DDTs.     

A Ten Years Monitoring of Chlorofluorocarbons at the Antarctica: Results and Perspectives

Abstract

Chlorofluorocarbons are man-made long lasting atmospheric pollutants of great environmental concern, responsible for important global change phenomena. Recently, they were replaced by hydrogenated halocarbons that, even if less persistent, do not lack in environmental impact. Atmospheric concentrations of these compounds were measured in Antarctica by gas chromatography. The extremely low atmospheric mixing ratios of these compounds require a pre-concentration step of the air sample on suitable adsorbent in order to meet the sensitivity of the analytical method Results obtained analyzing air samples collected in Antarctica since 1988 for the determination of CFC-12 and CFC-11 are reported, together with data concerning the less abundant species.