南极冰雪样品中超痕量重金属的分析测定进展

本文全面阐述了南极冰雪样品中重金属分析测定的发展概况和极地样品分析中出现的困难，评述了各种分析方法（包括富集技术、超灵敏的分析技术）的优缺点，并指出其发展方向。引用文献４７篇。     

A clean laboratory for ultralow concentration heavy metal analysis

Summary Laboratory facilities and methods are described which have been developed in our laboratory in collaboration with C. Patterson's group at the California Institute of Technology for the reliable measurement of various heavy metals at extremely low concentration levels down to the sub pg/g level in Antarctic and Greenland snow and ice. All analytical work is performed inside a clean laboratory pressurized with air filtered through high efficiency particle air filters and equipped with all-plastic laminar flow clean benches. High-purity water is produced by ion-exchange resins, and high purity acids from the US National Institute of Science and Technology are used. The various containers which are in contact with the samples are made of conventional low density polyethylene and FEP teflon. These containers are cleaned by immersion during several weeks in a succession of heated acid baths of increasing purity. Extremely careful blank determinations are made in order to quantitatively determine how much of the investigated metals is added to the samples from each separate reagent, from the walls of the various containers and from the air of the clean laboratory.     

Thallium and cadmium in recent snow and firn layers in the Canadian Arctic by atomic fluorescence and absorption spectrometries

Compared to the Antarctic and Greenland, the Canadian Arctic has seen extremely few trace metal studies on snow and ice. Surface, subsurface and depth samples of snow and firns were collected from the Agassiz Ice Cap, Ellesmere Island, Canada using clean room practices. Results for Tl (directly determined by LEAFS) and Cd (determined by GFAAS) are reported. To our knowledge, the thallium depth profile presented here is the first one so far reported for both polar systems, Greenland or other places. Tl concentrations peak in the winter-spring periods, when the Arctic atmosphere is loaded with foreign pollutants and suspended particulates which sometime severely reduce the visibility, creating a phenomenon commonly known as the Arctic haze. These results are in general accordance with the historical Arctic air pollution and acidity/conductivity data on ice cores. Surface concentrations of Tl range from 0.3 to 0.9 pg/g, which is a few times higher than those found in Antarctica. Cadmium shows seasonal characteristics similar to Tl although there is not a definite correlation between the two. However, there could be two predominant origins of metals which were deposited in the snow: Eurasian origin in January–April corresponding to high level metals (main deposition), and a less definite origin in May–December corresponding to low level metals.     

An evaluation of differential pulse anodic stripping voltammetry at a rotating glassy carbon electrode for the determination of cadmium,copper, lead and zinc in antarctic snow samples

A procedure is described for the determination without preconcentration of Cd, Cu, Pb and Zn in Antarctic snow, based on differential pulse anodic stripping voltammetry at a rotating glassy carbon electrode with in situ mercury plating. Thirty four surface snow samples from Adelaide Island in the Antarctic Peninsula demonstrate the scope of this method, and allow an assessment of local heavy metal sources such as the rock, the sea, and a manned base. The zinc data are affected by container contamination, but concentrations as low as 0.005, <0.02 and 0.05 ng g^-1 were measured for Cd, Cu and Pb, respectively.     

Thirty years of snow deposition at Talos Dome (Northern Victoria Land, East Antarctica): Chemical profiles and climatic implications

The aim of this study was to use ion chromatographic methods to measure trace species under clean conditions in Antarctic snow samples. Both anionic and cationic contents of the snow samples were measured using preconcentration columns for both the ion chromatographic systems due to the low concentrations typical of Antarctic snow and ice samples. Samples were collected from a snow-pit dug in Talos Dome (East Antarctica) during the 2003-2004 Italian Antarctic Campaign to perform a preliminary survey of the site chosen for deep drilling in the framework of the TALos Dome ICE core (TALDICE) international project. Stratigraphic dating was attempted for the entire snow-pit, covering about 30 years, in order to achieve climatic information from the chemical profiles of the measured species. In particular, ions coming mainly from biogenic sources were investigated as potential markers for historical reconstruction of parameters expressing atmospheric and oceanic circulation, such as Southern Oscillation Index (SOI). For the studied period, a good correlation between biogenic species and SOI and sea-ice extent in the Ross Sea sector was observed, suggesting that these ions, as recorded in Talos Dome, can be used as markers for the reconstruction of the oceanic and atmospheric conditions in the past.     

Determination of heavy metals at the pg/g level in Antarctic snow with DPASV and IDMS

Summary Differential pulse anodic stripping voltammetry (DPASV) and isotope dilution mass spectrometry (IDMS) were used to analyse heavy metals in Antarctic snow samples. It was possible to determine Pb and Cd with DPASV at the German Antarctic station Georg-von-Neumayer whereas the analyses of Pb, Cd, Tl, Cr, Ni, Cu, Zn, and Fe with IDMS were carried out at the University of Regensburg. 80% of the elemental concentrations in surface snow samples analysed with IDMS lay in the following ranges: Pb=3–40 pg/g, Cd<0.2–3 pg/g, Tl<0.2 pg/g, Cr<0.8–15 pg/g, Ni<4.8–40 pg/g, Cu<11–30 pg/g, Zn=30–500 pg/g, and Fe=(0.5–1.5)×10³ pg/g. In most cases an acceptable agreement between the DPASV and IDMS results was obtained for Pb and Cd. More than 50% of all Pb analyses agreed within a deviation of 0–10 pg/g. The Cd results between both methods usually deviated by less than 1 pg/g. Slightly higher Pb concentrations were analysed in the average with IDMS compared with DPASV. This effect was not observed for the Cd data. A possible explanation for this fact are non-ionic Pb species in the melted snow samples, which cannot be analysed by DPASV. One particular investigation of Pb concentrations showed that the analysed data with DPASV decreased with the increasing length of sun-shine after a snowfall when samples of the same origin were determined. Blank control is the major requirement for accurate analysis results of heavy metals in this low concentration range. On the other hand, accuracy must always be tested by independent analytical methods. In this work it is shown that Pb and Cd can be analysed directly in the Antarctica with DPASV and that the result of this method is in acceptable agreement with the definitive method IDMS.

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Bestimmung von Schwermetallen im pg/g Bereich in antarktischen Schneeproben durch differentielle Pulsinversvoltammetrie und massenspektrometrische Isotopenverdünnungsanalyse

     

Ion chromatographic determination of common ions at ultratrace levels in Antarctic snow and ice

The simultaneous determination of major impurities present in Antarctic snow and ice at ng g^? (ppb) concentrations by ion chromatography is described. Calibration data are presented for ammonium, sodium, potassium, chloride, nitrate and sulphate ions. Special attention is paid to the different ways of removing field contamination from ice and snow cores and suitable equipment is described. The results provide evidence against the validity of published sets of concentration data for nitrogen-containing compounds (NO^?₃ and NH⁺₄ in Antarctic snow, and demonstrate a crucial contamination problem in the determination of ammonium ions.     

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.     

Spectrofluorimetric Evidence of the Transport of Marine Organic Matter in Antarctic Snow Via Air-Sea Interaction

Abstract

This paper considers the importance of marine aerosol in the atmosphere. As a consequence of its peculiar generation mechanism, it is also considered as a possible contributor to the transport of man-made microcomponents via air-sea interaction, especially in remote sites.

In view of future marine aerosol studies, the dominant presence of marine aerosol components in coastal Antarctic snow is discussed the presence of fluorescent marine organic matter in Antarctic snow is shown. Its “marum” nature is evidenced.

We give a tentative interpretation of the experimental data, and make a hypothesis concerning the variations in marine aerosol composition in correspondence to various altitudes.     

Recent advances in measurement of Pb isotopes in polar ice and snow at sub-picogram per gram concentrations using thermal ionisation mass spectrometry

Techniques for Pb measurements have reached the stage where Antarctic ice with sub-picogram per gram concentrations can be reliably analysed for isotopic composition. Here, particular attention has been given to measuring the quantity of Pb added during the decontamination and sample storage stages of the sample preparation process because of their impact on accuracy at low concentrations. These stages, including the use of a stainless steel chisel for the decontamination, contributed ∼5.2 pg to the total sample analysed, amounting to a concentration increase of ∼13 fg g⁻¹, which is significantly less than expected. Consequently, the corrections to the isotopic ratios and concentration were also smaller. Other contributions to the blank, such as Pb fallout onto critical working areas in the HEPA-filtered air laboratories, were also relatively small as was the amount of Pb leached from preconditioned perfluoroalkoxy (PFA) beakers during sample processing. The ion source contributed typically 89±19 fg to the blank. Although this was relatively large, its influence depended upon the amount of Pb available for analysis and it had the greatest impact when small volumes of samples with a very low concentration were analysed. A 15 months investigation of the leaching characteristics of Pb from a low-density polyethylene (LDPE) sample storage bottle showed 11 fg cm⁻² per day was released immediately following the initial 2 months cleaning process, but this decreased to immeasurable values after a further 3 months of cleaning.     

Development of a sampling and flow injection analysis technique for iron determination in the sea ice environment

A trace metal clean method for sampling and analysis of iron is set up and applied to sea ice and its associated snow, brine, and underlying seawater sampled during the Antarctic expedition “ARISE in the East” (Antarctic Remote Ice Sensing Experiment, AA03-V1, September-October 2003, 64-65°S/112-119°E, RV Aurora Australis). For clean sampling, a non-contaminating electropolished stainless steel ice corer is designed in conjunction with a polyethylene lathe equipped with Ti chisels to remove possibly contaminated outer layers of ice cores. A portable peristaltic pump with clean tubing is used on the ice to sample the underlying seawater (interface ice-water = 0, 1 and 30 m) and sea ice brine from access holes. Considering the extreme range of salinities (1-100) and Fe concentrations (0.1-100 nM) previously observed in similar environments, it is of paramount importance to set up a simple and sensitive Fe analyser adapted to such gradients. We use a flow injection analysis (FIA) technique and successfully demonstrate its capability to measure Fe concentrations directly in the sample without an on-line preconcentration/matrix separation step. We test the sensitivity, accuracy, precision and long-term stability of the analytical procedure. Also we explore and remediate interferences from a suite of other trace elements, such as Ni, Cd, Cr, Mn, Cu, Zn and Co. Analysis of reference materials NASS-5 and CASS-3 gives a good agreement with the certified values. Repeated measurements over a period of 5 months of an “in-house” Antarctic seawater standard yields a concentration of 1.02 ± 0.07 nM (n = 17, 1σ). The detection limit (3σ of the blank) is on average 0.12 nM. We report here results of the Fe distribution in sea ice that are in good agreement with previously published data. To our knowledge, this work provides the first complete profiles of total dissolvable and dissolved Fe in sea ice.     

Recent Decrease in the Lead Concentration of Antarctic Snow

Abstract

Differential Pulse Anodic Stripping Voltammetry (DPASV) was applied to determine the lead concentration in recent snow at two sites in the Victoria Land region, East Antarctica. Snow samples were collected during the 6th Italian Scientific Expedition to Antarctica (austral Summer 1990–91) along the wall of 2.5 m-deep hand-dug pits and by coring to a depth of about 11 m. The measurements revealed that lead content in Antarctic snow increased continuously from 1965 (about 3 pg/g) to the early 1980s (maximum about 8 pg/g), after which a marked, rapid decrease took place during the second half of 1980s, down to 2–4 pg/g in 1991. Estimates of the lead contributions from rocks and soils, volcanoes and the marine environment, together with analysis of statistical data on non-ferrous metal production and gasoline consumption, and the corresponding lead emissions into the atmosphere of the Southern Hemisphere, show that a net anthropogenic component is present and support the hypothesis that the trend observed in Antarctic snow may be related to lead consumption in gasoline, which firstly was on the rise, then declined owing to the increased use of unleaded gasoline.     

Occurrence of Selected Metals in Wastewater Effluent and Surface Water in Ireland

Metals occur naturally in the environment and as constituents of the Earth’s crust. They have many uses, and metals such as iron, copper, and zinc are widely used in industries. Elevated levels of metals in the environment also occur as a result of human activities (municipal, residential, and traffic–related activities). A list of 15 metals chosen for this study included priority substances and those listed in the European Union Water Framework Directive 2000/60/EC. The concentrations of heavy metals in the environment are affected by several factors that must be taken into account when monitoring heavy metals released into the environment through wastewater treatment plants (WWPTs). This work examines the concentrations of metals found in WWPTs and the effects of treatment type on dissolved metal concentrations. Effluent samples were collected from the outflow of nine WWPTs in Dublin and Cork, Ireland from July 2009 to June 2011. All samples were found to contain priority metals that exceeded environmental quality standards in several cases. We present the frequency of occurrence and concentrations of metals in effluents of studied WWPTs and discuss relationships between the occurrence of heavy metals, the influence of factors such as industrial inputs, levels of treatment at WWPTs, and percentage urban area in an agglomeration. The results of this study are an indication that WWPTs may be contributing to the high levels of heavy metals found at discharge points back into river systems.     

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.     

Determination of nitrate at the ng/g level in Antarctic snow samples with ion chromatography and isotope dilution mass spectrometry

Summary Nitrate traces in Antarctic snow and hoar-frost samples, which were collected on the Ekström ice shelf during January and February, 1987, were determined with ion chromatography at the German Antarctic station Georg-von-Neumayer. For comparison, sample preparations for isotope dilution mass spectrometry were also carried out at the German station whereas the mass spectrometric measurements took place in Regensburg. Comparable reproducibilities of 1%–5% were found for both methods of analysing nitrate concentrations in the range of 40–190 ng/g. An excellent agreement of the results of both methods with an average deviation of 0.1% was found in three sets of firn core samples. The average relative deviation of the ion chromatographic values from those of isotope dilution mass spectrometry was –10% for eleven hoar-frost and surface snow samples. The highest nitrate concentrations were analysed in hoar-frost samples with an average value of 548 ng/g. The following order, which corresponds to the age of nitrate depositions, was: new snow (206 ng/g), old surface snow (146 ng/g), and snow from firn cores (61 ng/g). The decreasing concentration with the age of samples is the result of re-emission of nitrate into the atmosphere after its deposition by snow. A seasonal variation of the nitrate concentration with a summer maximum and a winter minimum was observed for firn core samples. Accurate results of analytical data, which are published from all parts of Antarctica today, can only be guaranteed by the application of independent methods, e.g., by ion chromatography and isotope dilution mass spectrometry as it is shown in this work.

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Bestimmung von Nitrat im ng/g Bereich in antarktischen Schneeproben durch Ionen-Chromatographie und massenspektrometrische Isotopenverdünnungsanalyse

     

Microdetermination of Heavy Metal Chelates by High-Performance Liquid Chromatography

Abstract

Adsorption chromatography of diethyldithiocarbamate chelates of heavy metals is described. Determination of heavy metals including Hg (II), Cd (II), Pb (II), Cr (VI), Bi (III) and Cu (II) in micro to nano gram order is successfully carried out with good accuracy and reproducibility by a deactivated silica gel column. Separative microdetermination of these chelates is accomplished within 12 min, and selective determination is also possible by choosing the detection wavelength of a UV detector.     

北江干流沉积物重金属污染生态风险评价

通过北江干流水体沉积物重金属含量,研究其典型污染物的潜在生态风险。采集了北江干流韶关至清远段7份沉积物样品,经混酸消解后,以电感耦合等离子体质谱仪测定沉积物中重金属含量,并对沉积物重金属分布特征进行了分析。同时利用Hakanson的潜在生态危害指数（RI）评价模式,对北江干流沉积物重金属生态风险进行了评价。评价结果表明,北江干流沉积物中重金属综合生态危害程度均表现为很高级别,其生态危害因子Pb、Cd已成为北江干流突发性水污染事故潜在预警因子。     

Preliminary study of HCHO spatial and temporal distribution from Coastal to Plateau areas in Antarctica

Formaldehyde concentrations were determined in over 1800 snow samples (snowpit, firn cores and superficial snow) from Antarctica by a sensitive spectrofluorimetric Flow Injection Analysis method. The method performances (detection limit: 55?ng/L; reproducibility: 2.5% at 1?µg/L level; linear range: 0.1–3000?µg/L) allowed a reliable determination of formaldehyde content in all the collected samples. The range of determined concentrations was 0–70?µg/L with a mean concentration of 7.7?µg/L and a median concentration of 5.8?µg/L. The formaldehyde background level was estimated at a few micrograms per liter in coastal and plateau areas of Northern Victoria Land. In some stations the background values are modulated by HCHO deposition events recurring over relatively large time periods.     

Contents of some heavy metals in plants from Saginaw Bay (Lake Huron) and some small lakes in wilderness areas of Michigan's Upper Peninsula as analyzed by neutron activation analysis

Our results indicate that the highest concentrations of heavy metals occurred in those plants collected near the mouth of the Saginaw River. The alga, Cladophora sp., and the flowering plant, Typha augustifolia (cat-tail), are notable for the high concentration of heavy metals that they accumulated. In addition, several other species that were sampled from small lakes in Michigan's Upper Peninsula contained higher concentrations of certain metals (Ba, Cr, Rb) than from any samples obtained from Saginaw Bay. Different organs of the same species, or of the same plant, such as cat-tail, vary widely in concentrations of the same elements. A computer-derived analysis of our data is presented, and the implications of our results as they relate to pollution by heavy metals in fresh-water lakes is discussed. This work was supported by a private subsidy from Edna Newnan, Bloomfield Hills, Michigan to whom we express our thanks for hernerous support. We also wish to thank the Division of Biological Sciences, The University of Michigan, for making funds available for the computer analyses performed in this study.     

Characterization of Heavy Metals in Soil Near Coal Mines and a Power Plant in Huainan,China

The environmental and health hazards posed by heavy metals are significant due to their toxicity and bioavailability. Thirty-two soil samples were collected from residential areas around three coal mines and a power plant to assess the environmental and health implications caused by mining activities. The concentrations of heavy metals in soil were determined by inductively coupled plasma mass spectrometry. To evaluate the risk levels, the geo-accumulation index and health risk assessment were determined. The concentrations of metals in power plant soil were generally higher than those in coal mine soil, suggesting a higher release during coal combustion. The results demonstrate that the soils in the vicinity of Xinzhuangzi Mine and Luohe Power Plant are moderately contaminated by arsenic and cadmium. The analysis of the health risk of the metals indicated that the non-carcinogenic and carcinogenic adverse effects to residents due to heavy metal exposure are negligible. However, more attention should be paid around the power plant for the unacceptable level of carcinogenic risk. Based on the results of the environmental and health risk assessment, priority control components in Huaian have been identified. The study provides a comprehensive assessment of soil heavy metal implications derived from mining activity in this region in China and is helpful for pollution control and environmental management.