Distribution of major,minor and trace elements in Antarctic offshore and Coastal seawaters: correlation among sites and variables by pattern recognition

The composition of seawater in the Ross Sea (Antarctica) was investigated. The distribution of heavy metals (Cd, Cu, Fe, Mn, Ni), minor and trace (B, Ba, Li, Sr, Si) and major (Na, K, Ca, Mg) elements in coastal and offshore sites was determined. The samples were collected during the XIII Campaign of the Italian “National Programme of Research in Antarctica”, PNRA, at different depths and different stages of the Antarctic summer. In the subsequent campaign the concentrations in the water top micro-layer, and just below it, were compared. Results are also given for the data treatment by pattern recognition.     

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.     

Neutron activation analysis of Urartian pottery from eastern Anatolia

The assessment of environmental pollution of the coastal areas of the Malaysian Peninsula was done by analyzing the contents of the heavy and trace elements in the bivalves blood clams (Anadara granosa) and green mussels (Perna viridis) and sediments at twenty-two sampling stations to look for prevailing trends. Heavy and trace elements analyzed in this study were As, Cd, Cr, Cu, Pb, Se and Zn. Two techniques, namely the neutron activation analysis (NAA) and atomic absorption spectrophotometry (AAS) were used in the quantitative determination of the heavy metals while Marine Sediment Reference Material (BCSS) and Lobster Hepatopancreas (TORT-1) provided the certified reference materials in the quality assurance control. The potential use of these bivalves as suitable bio-indicators was evaluated from correlation tests based on the concentrations of heavy and trace elements in the sediment-metals system to those in the bivalves.     

A new Antarctic certified reference material for trace elements: Adamussium colbecki

The certification of a new reference material for trace elements based on the Antarctic bivalve Adamussium colbecki is reported. This certified reference material (CRM), labelled IRMM 813, was produced in the frame of the Italian National Program for Research in Antarctica (Programma Nazionale di Ricerca in Antartide, PNRA). About 40 kg of the scallop were collected at Terra Nova Bay (Ross Sea). The raw material was freeze-dried, jet-milled and homogenized so as to make it suitable for certification. The elements selected for the certification project were As, Cd, Cu, Cr, Fe, Mn, Ni and Zn. Homogeneity and short- and long-term stability were preliminarily investigated so as to assess the suitability of the freeze-dried mass as a candidate CRM. The candidate material was found to be fit for purpose, thus allowing the following phases of the certification project to be undertaken, in the first place the selection of expert laboratories for the accomplishment of the certification campaign. Eighteen laboratories from twelve countries accepted to participate in the certification project which thus could be successfully completed.     

Slurry sampling hydride generation atomic absorption spectrometry for the determination of extractable/soluble As in sediment samples

A method combining the sampling of slurry pretreated by ultrasonic agitation and microwave assisted extraction with hydride generation atomic absorption spectrometry (HGAAS) for the determination of arsenic in sediment samples is proposed and evaluated. The pretreatment of slurried samples by ultrasonication enabled the extraction of (approximately) up to 85% of arsenic from the studied sediment samples. The further (slight) improvement of the efficiency of extraction was accomplished by the introduction of a short microwave-accelerated treatment. l-cysteine was used as an efficient pre-reduction reagent. The accuracy and precision of the slurry sampling HGAAS method were studied using the certified reference materials: Sediment GBW 30043 (NRCCRM, People's Republic of China), Sediment NIST 2704 (NIST, USA) and Marine Sediment BCSS-1 (NRCC, Canada). The relative standard deviation of the full (overall) analytical procedure was 8.5% and an absolute limit of detection of 2.75 ng was achieved. Factors which influence the reliability of this method are, for example, the choice of slurry liquid phase (extraction medium), sample homogeneity and, in particular, very effective mixing of slurries.     

Certification of standard reference material (SRM) 1941a, organics in marine sediment

SRM 1941a, Organics in Marine Sediment, has been recently issued with certified concentrations for 23 polycyclic aromatic hydrocarbons, 21 polychlorinated biphenyl congeners, 6 chlorinated pesticides, and sulfur. Noncertified concentrations have been also reported for additional PAHs, PCB congeners, and chlorinated pesticides and for percent total organic carbon (TOC), aliphatic hydrocarbons, and trace elements. SRM 1941a is the most extensively characterized natural matrix SRM issued by the National Institute of Standards and Technology (NIST).     

A study on sampling representativeness of IAEA RM SD-M-2/TM Marine Sediment by INAA

The homogeneity of IAEA RM SM-M-2/TM Marine Sediment was tested by INAA. The sampling constants a and b have been determined for 6 elements.     

Determination of chlorine, bromine and iodine in rock samples by radiochemical neutron activation analysis

Chlorine, bromine and iodine (hereafter, halogens) were detemined for rock samples by radiochemical neutron activation analysis. The powdered samples and reference standards prepared from chemical reagents were simultaneously irradiated for 10 to 30 minutes with or without a cadmium filter in a TRIGA-II reactor at the Institute for Atomic Energy, Rikkyo University. The samples were subjected to radiochemical procedures of halogens immediately after the irradiation. Iodine was firstly precipitated as PdI₂, and chlorine and bromine were successively precipitated as Ag-halides at the same time. In this study, geological standard rocks, sedimentary rocks and meteorites were analyzed for trace halogens. In some Antarctic meteorites, iodine contents were observed to be anomalously high. Chlorine contents also are somewhat high. The overabundance of iodine and chlorine must be caused by terrestrial contamination on the Antarctica.     

Trends of volatile chlorinated hydrocarbons and trihalomethanes in Antarctica

In order to understand behaviour and environmental fate of manmade chemicals in remote and cold areas, during the XXVII Italian Expedition carried out in Antarctica throughout the austral summer 2011/2012, superficial snow and lake water were sampled along the Ross Sea's South coast and their content of some low-molecular weight volatile halogenated hydrocarbons was evaluated. In consideration of their important role in stratospheric ozone chemistry, some volatile chlorinated hydrocarbons (VCHCs) and trihalomethanes (THMs) were investigated. The analyses were realised with a dedicated system composed by a purge-and-trap injector coupled to a gas chromatograph with a mass spectrometer (PTI-GC-MS) operating in SIM mode. The investigated VCHCs (chloroform; 1,1,1-trichloroethane; tetrachloromethane; trichloroethylene and tetrachloroethylene) were present in all analysed samples, and concentration levels ranged from units to hundreds of ng L^?1 according to considered matrix. For the first time, THMs (bromoform; dibromochloromethane; bromodichloromethane), were measured in Antarctic lake waters and freshly deposited snow; their concentration levels ranged from units to tens of ng L^?1. In order to assess eventual temporal variations, VCHC content in aqueous Antarctic matrices was compared with levels occurring in the past Italian Antarctic expeditions: for some banned substances, a decrease in concentration was observed, probably due to worldwide use restrictions. Finally, current Antarctic and Italian VCHC and THM levels in snow and lake water samples were compared and were found to be quite similar, differing at most by one order of magnitude, corroborating the hypothesis of an accumulation of halogenated compounds in Antarctic aqueous matrices.     

Ultrasensitive determination of heavy metals at the sub-picogram per gram level in ultraclean Antarctic snow samples by inductively coupled plasma sector field mass spectrometry

Assessing changes in heavy metals concentrations in Antarctic snow dated from the last century is of high interest to determine to which extent the most remote regions of our planet are contaminated for these metals, and to have a better understanding into their long-range transport from the different natural and anthropogenic source areas to the Antarctic continent. Such investigations are unfortunately very difficult because the concentrations to be measured are exceedingly low, down to the sub-picogram per gram level. They require a strict control of contamination problems from field sampling to laboratory analysis, and the use of ultrasensitive analytical techniques.

We present here important advances in the analytical protocols for obtaining reliable data on the occurrence of heavy metals in Antarctic snow. Utmost precautions were taken to obtain a series of large size ultraclean snow blocks from the wall of a 8.3 m clean hand-dug pit at a remote site in Coats Land, Antarctica. These blocks were then sub-sampled inside a laminar flow clean bench in a cold room, using ultraclean protocols, to provide high-resolution heavy metal times series. V, Cr, Mn, Cu, Ag, Ba, Pb, Bi and U were then determined directly, without any pre-concentration step, by the ultrasensitive inductively coupled plasma sector field mass spectrometry (ICP-SFMS) technique in clean room conditions. Calibration of the instrument was performed using ultralow concentrations standards, and extreme precautions were taken to ensure the cleanliness of the instrument and its introduction system. The results show that it is possible to accurately measure a variety of heavy metals in Antarctic snow, down to the sub-picogram per gram level, using this approach. Examples of the data obtained for the Coats Land site are finally presented. For U, the observed concentrations range from 0.004 to 0.21 pg/g; they are the first data ever obtained for this metal for Antarctic snow and ice.     

Critical evaluation of laboratory performance from IAEA-452 (fish scallop) inter-comparison exercise results

The International Atomic Energy Agency Marine Environmental Laboratory (IAEA-MEL) conducted an intercomparison exercise for the “Trace elements and methyl mercury in fish scallop: IAEA-452” in 2009. The Neutron Activation Analysis (NAA) laboratory at PINSTECH, Pakistan took part in this exercise. Comparison with the IAEA results showed that of the 18 elements reported to the IAEA 7 had unacceptable z-scores while the data for two elements was questionable (2< |z-score| <3). Upon investigation it was discovered that the large number of elements having unacceptable z-scores was due to human error and the greater difficulty in analyzing biological samples which have low amounts of trace elements. Therefore selection of values corresponding to matrix matched reference materials (RMs), such as IAEA-436 and IAEA-407, and to non-interfering peaks the results obtained became comparable to the IAEA results with only the result for As having |z-score|> 3.     

Two new marine sediment standard reference materials (SRMs) for the determination of organic contaminants

Two new marine sediment standard reference materials (SRMs), SRM 1941b Organics in Marine Sediment and SRM 1944 New York/New Jersey Waterway Sediment, have been recently issued by the National Institute of Standards and Technology (NIST) for the determination of organic contaminants including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyl (PCB) congeners, and chlorinated pesticides. Both sediment SRMs were analyzed using multiple analytical methods including gas chromatography/mass spectrometry (GC/MS) on columns with different selectivity, reversed-phase liquid chromatography with fluorescence detection (for PAHs only), and GC with electron capture detection (for PCBs and pesticides only). SRM 1941b has certified concentrations for 24 PAHs, 29 PCB congeners, and 7 pesticides, and SRM 1944 has certified concentrations for 24 PAHs, 29 PCB congeners, and 4 pesticides. Reference concentrations are also provided for an additional 58 (SRM 1941b) and 39 (SRM 1944) PAHs, PCB congeners, and pesticides. SRM 1944, which was collected from multiple sites within New York/New Jersey coastal waterways, has contaminant concentrations that are generally a factor of 10–20 greater than SRM 1941b, which was collected in the Baltimore (Maryland) harbor. These two SRMs represent the most extensively characterized marine sediment certified reference materials available for the determination of organic contaminants.Electronic Supplementary Material Supplementary material is available in the online version of this article at . A link in the frame on the left on that page takes you directly to the supplementary material.     

Preparation and analysis of a marine sediment reference material for the determination of trace organic constituents

Summary A new marine sediment Standard Reference Material (SRM) has been prepared and analyzed for the determination of trace organic constituents. SRM 1941, Organics in Marine Sediment, has been certified for concentrations of 11 PAHs using results obtained from gas chromatography (GC) with flame ionization detection, gas chromatography-mass spectrometry, and liquid chromatography with fluorescence detection. Non-certified values for 24 additional PAHs are also reported. GC with electron capture detection was used to provide non-certified concentrations for 15 PCB congeners and 7 chlorinated pesticides. In addition to the organic contaminants, concentrations of 32 major and trace elements were determined using neutron activation analysis, and the sulfur content was also determined using isotope dilution thermal ionization mass spectrometry.     

Possibilities and limitations of the total reflection X-ray fluorescence spectrometry for the determination of low Z elements in biological samples

The analytical capability of the laboratory scale vacuum total reflection X-ray fluorescence (TXRF) spectrometer (Wobistrax) was studied for the determination of the Z elements (Na, Mg, P, S, K and Ca) in different biological matrices represented by the following certified reference materials: MURST-ISS-A2 Antarctic krill, IAEA-331 spinach, NIST 1577a bovine liver, and SERONORM™ Trace Elements Serum Level 1.First, the stability of the response factors (relative sensitivity) against Ti internal standard was checked in the concentration range of 1 to 1000 mg/L in a diluted nitric acid matrix. It has been found that the upper limit of the analytical concentration range for K and Ca can be as high as 1000 mg/L; on the other hand, the remaining elements cannot be determined above a concentration of some tens mg/L.The established response factors were used for the elemental analysis of the four certified reference materials after normal-volume microwave assisted acid digestion. In the case of the serum sample, different preparation methods were compared as follow: direct analysis, microwave assisted acid digestion in normal-volume and micro-vessels, as well as the vapor-phase digestion directly on the TXRF carrier plates.On the basis of the results, the normal-volume digestion results in rather high dilution of the samples; thus, elements at low concentration could not be detected in some of the samples. On the other hand, this method offers the highest rate of both organic matrix decomposition and inorganic matrix dilution; thus, the background and the standard deviation of the results were the lowest. In general, this method was found to be useful for the analysis of samples with high dissolved (organic + inorganic) content if the analytes are present at a concentration considerable above the quantification limit.In the case of the microscale and the vapor-phase digestion, both the organic and inorganic matters remain at elevated concentration; thus, higher background and self-absorption of the fluorescent radiation occurred, deteriorating the analytical performance.     

Measurement of voltammetric peak area and resolution of overlapping peaks in the simultaneous determination of copper, lead, cadmium, and nickel in environmental matrixes

Peak area was used for the simultaneous determination of copper(II), lead(II), cadmium(II), and nickel(II) in environmental matrixes by differential pulse voltammetry. The voltammetric measurements were performed with a conventional 3-electrode cell and an ammonia-ammonium chloride buffer, pH 9.1, as the supporting electrolyte. The analytical procedure was verified first in aqueous reference solutions and later by analysis of the standard reference materials Estuarine Sediment BCR-CRM 277 and River Sediment BCR-CRM 320. The precision and accuracy of the method, expressed as the relative standard deviation and the relative error, respectively, were <5% in all cases; the detection limit for each element under the experimental conditions used was in the range 1-5 microg/L. In the case of mutual interference between neighboring elements, an analytical procedure is proposed that is based on the standard additions technique, which allows the resolution of the overlapping voltammetric peaks.     

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.     

Ultratrace analysis of Antarctic snow samples by reaction cell inductively coupled plasma mass spectrometry using a total-consumption micro-sample-introduction system

In this work, a new sensitive procedure for the determination of ultratrace elements in snow samples based on quadrupole ICP-MS has been developed. After filtration through a 0.5 microm PTFE membrane (for dissolved element determination) or acidification with 0.5% nitric acid (for acid dissolvable element determination), the analytes were preconcentrated by sample volume reduction and analysed by ICP-MS. Micro-samples were efficiently introduced into the plasma source at 20 microl min(-1) uptake rate by using a PFA micronebulizer coupled to an evaporation chamber of the torch integrated sample introduction system (TISIS). As a result, the amount of sample required was about one order of magnitude lower than that required with a conventional liquid sample introduction system. In order to improve the transport efficiency, the TISIS chamber was electrically-heated at 70 degrees C and a sheathing gas stream was used to protect the aerosol from the chamber walls. Under these conditions, negative solvent plasma effects were no more severe than for conventional systems, because the total solvent plasma load was 20 mg min(-1). The operating parameters were optimized to obtain maximum sensitivity, while limiting oxides and double charge ion formation. The polyatomic interferences were removed by applying the dynamic reaction cell (DRC) technique, using ammonia as the reaction gas. Under the optimized conditions, limits of detection ranged from 0.02 to 4.5 pg g(-1), allowing the determination of Cr, V, Fe, Mn, Pb, Zn, Cd, Co and Cu in Antarctic snow samples. Signal repeatability was lower than 10% which prevented the use of an internal standard. Precision of the procedure ranged from 2.0% to 5.6%. The accuracy of the method was verified by the analysis of both certified reference water and surface snow samples collected in coastal and inland areas of Antarctica. The DRC program used, the short wash out and signal stabilization times registered under these conditions led to a 10 h(-1) sample throughput.     

Finite group theory for large systems. 3. Symmetry-generation of reduced matrix elements for icosahedral C(20) and C(60) molecules

This paper uses symmetry-generation to simplify the determination of Hamiltonian reduced matrix elements. It is part of a series on using computers to apply finite group theory to quantum mechanical calculations on large systems. Symmetry-generation is an expression of the whole molecule as a sum of symmetry transformations on a smaller reference structure. Then on a suitably-conditioned symmetry-adapted basis, the reduced matrix elements of the Hamiltonian are averages of certain elements of the simpler reference structure matrix. The smaller the reference structure, the greater is the computational savings. Single atom reference structures are used here for the Hückel treatment of icosahedral C(20) and C(60) fullerenes. The analytical power of this approach is illustrated by determining the two bond lengths of C(60) from spectral data.     

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.     

玻璃标样结合硫内标归一定量技术在激光剥蚀-等离子体质谱分析硫化物矿物中的应用

以硬石膏矿物标样中Ca相对于S的灵敏度因子为基准,将玻璃标样中主量和痕量元素相对于Ca的灵敏度因子转换成元素相对于S的灵敏度因子,建立了多玻璃标样结合硫内标归一定量技术分析硫化物单矿物多元素的新方法。利用本方法分析了美国合成多金属硫化物矿物标样MASS-1中20种元素,主量元素分析结果的相对误差小于10%,痕量元素分析结果几乎都落在给定值±不确定度范围内。利用本方法对12个硫化物单矿物分析结果表明,绝大多数主量元素含量测定值的相对误差小于10%,且多数主量元素甚至优于以MASS-1为外标、内标归一定量法及内标校准法分析结果,而痕量元素与MASS-1校准结果较为一致。本方法克服了基体不匹配的问题,能比较准确地定量分析硫化物矿物中的主成分S,可用于定量校准硫化物矿物。