Volatile halogenated organic compounds containing bromine and iodine, which are naturally produced in the ocean, are involved in ozone depletion in both the troposphere and stratosphere. Three prominent compounds transporting large amounts of marine halogens into the atmosphere are bromoform (CHBr3), dibromomethane (CH2Br2) and methyl iodide (CH3I). The input of marine halogens to the stratosphere has been estimated from observations and modelling studies using low-resolution oceanic emission scenarios derived from top-down approaches. In order to improve emission inventory estimates, we calculate data-based high resolution global sea-to-air flux estimates of these compounds from surface observations within the HalOcAt (Halocarbons in the Ocean and Atmosphere) database (https://halocat.geomar.de/). Global maps of marine and atmospheric surface concentrations are derived from the data which are divided into coastal, shelf and open ocean regions. Considering physical and biogeochemical characteristics of ocean and atmosphere, the open ocean water and atmosphere data are classified into 21 regions. The available data are interpolated onto a 1 degrees x 1 degrees grid while missing grid values are interpolated with latitudinal and longitudinal dependent regression techniques reflecting the compounds' distributions. With the generated surface concentration climatologies for the ocean and atmosphere, global sea-to-air concentration gradients and sea-to-air fluxes are calculated. Based on these calculations we estimate a total global flux of 1.5/2.5 Gmol Br yr(-1) for CHBr3, 0.78/0.98 Gmol Br yr(-1) for CH2Br2 and 1.24/1.45 Gmol Br yr(-1) for CH3I (robust fit/ordinary least squares regression techniques). Contrary to recent studies, negative fluxes occur in each sea-to-air flux climatology, mainly in the Arctic and Antarctic regions. "Hot spots" for global polybromomethane emissions are located in the equatorial region, whereas methyl iodide emissions are enhanced in the subtropical gyre regions. Inter-annual and seasonal variation is contained within our flux calculations for all three compounds. Compared to earlier studies, our global fluxes are at the lower end of estimates, especially for bromoform. An under-representation of coastal emissions and of extreme events in our estimate might explain the mismatch between our bottom-up emission estimate and top-down approaches.

We present results of three field campaigns using active longpath DOAS (Differential Optical Absorption Spectroscopy) for the study of reactive halogen species (RHS) BrO, IO, OIO and I2. Two recent field campaigns took place in Spring 2002 in Dagebüll at the German North Sea Coast and in Spring 2003 in Lilia at the French Atlantic Coast of Brittany. In addition, data from a campaign in Mace Head, Ireland in 1998 was partly re-evaluated. During the recent field campaigns volatile halogenated organic compounds (VHOCs) were determined by a capillary gas chromatograph coupled with an electron capture detector and an inductively coupled plasma mass spectrometer (GC/ECD-ICPMS) in air and water. Due to the inhomogeneous distribution of macroalgae at the German North Sea Coast we found a clear connection between elevated levels of VHOCs and the appearance of macroalgae. Extraordinarily high concentrations of several VHOCs, especially CH3I and CH3Br of up to 1830 pptv and 875 pptv, respectively, were observed at the coast of Brittany, demonstrating the outstanding level of bioactivity there. We found CH2I2 at levels of up to 20 pptv, and a clear anti-correlation with the appearance of IO. The IO mixing ratio reached up to 7.7±0.5 ppt(pmol/mol) during the day, in reasonable agreement with model studies designed to represent the meteorological and chemical conditions in Brittany. For the two recent campaigns the DOAS spectra were evaluated for BrO, OIO and I2, but none of these species could be clearly identified (average detection limits around 2 ppt, 3 ppt, 20 ppt, resp., significantly higher in individual cases). Only in the Mace Head spectra evidence was found for the presence of OIO. Since macroalgae under oxidative stress are suggested to be a further source for I2 in the marine boundary layer, we re-analyzed spectra in the 500–600 nm range taken during the 1998 PARFORCE campaign in Mace Head, Ireland, which had not previously been analyzed for I2. We identified molecular iodine above the detection limit (~20 ppt), with peak mixing ratios of 61±12 ppt. Since I2 was undetectable during the Brittany campaign, we suggest that iodine may not be released into the atmosphere by macroalgae in general, but only by a special type of the laminaria species under oxidative stress. Only during periods of extraordinarily low water (spring-tide), the plant is exposed to ambient air and may release gaseous iodine in some way to the atmosphere. The results of our re-analysis of spectra from the PARFORCE campaign in 1998 support this theory. Hence, we feel that we can provide an explanation for the different I2 levels in Brittany and Mace Head.

This chapter contains sections titled: Introduction SEC/ICP-MS System and the Isotope Dilution Technique Determination of Heavy Metal–ROS Complexes in Fractions Separated by SEC Correlation of Metal–ROS Complexes with other Analytical Data Kinetically Stable Cr(III) and Co(III) Complexes of ROS Determination of Halogen–ROS Compounds in Fractions separated by SEC Conclusions References

The distribution of halogens in various fractions of humic substances (HS), separated by their molecular weight, was found to be different for the different halogens. This was demonstrated for chlorine, bromine, and iodine in sewage and brown water samples by applying inductively coupled plasma mass spectrometry coupled with size-exclusion chromatography. Quantification of the different fractions of iodinated humic substances was obtained by quadrupole mass spectrometry in connection with the isotope dilution technique using an I-129-enriched splice solution. Quantitative analysis was not possible for the corresponding chlorine and bromine species because of spectrometric interferences in the quadrupole instrument. The ageing of HS/halogen species was followed with respect to possible transformations of these species in a ground and sewage water sample up to eight weeks. Even if a distinct structural variation of the humic substance was observed with time by measuring the UV absorption, chlorine remained in the same molecular weight fraction and only a small change was found for the HS/bromine species after eight weeks. In contrast to these findings a substantial transformation of HS/iodine compounds took place, which demonstrated that the transfer probability of halogens from one to another HS fraction is increased with decreasing strength of the halogen bond to carbon. By comparing the results of an original sewage water sample with a filtered one and with another one which was enriched by microorganisms cultivated from the same original sample, a strong microbiological influence on the transformation of HS/iodine species was found. A quantitative balance of the corresponding HS/iodine fractions was calculated for an ageing period of right weeks showing that iodine was preferably transferred to newly formed UV active HS substances of high molecular weight. In total, no iodine was released from the humic substances.

The analytical fractionation of aquatic humic substances (HS) by means of immobilized metal-chelate affinity chromatography (IMAC) on metal-loaded chelating ion exchangers is described. The cellulose HYPHAN, loaded with different trivalent ions, and the chelate exchanger Chelex 100, loaded to 90% of its capacity with Fe(III), were used. The cellulose HYPHAN, loaded with 2% Fe(III), resulted in HS distribution coefficients Kd of up to 10(3.7) mL/g at pH 4.0 continuously decreasing down to 10(1.5) at pH 12, which were appropriate for HS fractionation by a pH-depending chromatographic procedure. Similar distribution coefficients Kd were obtained for HS sorption onto Fe(III)-loaded Chelex 100. On the basis of Fe-loaded HYPHAN both, a low-pressure and high-pressure IMAC technique, were developed for the fractionation of dissolved HS applying a buffer-based pH gradient for their gradual elution between pH 4.0 and 12.0. By coupling the Chelex 100 column under high-pressure conditions with an inductively coupled plasma mass spectrometer an on-line characterization of HS metal species could be achieved. Using these fractionation procedures a number of reference HS were characterized. Accordingly, the HA (humic acids) and FA (fulvic acids) studied could be discriminated into up to 6 fractions by applying cellulose HYPHAN, significantly differing in their Cu(II) complexation capacity but hardly in their substructures assessed by conventional FTIR. In the case of using Chelex 100 exchanger resin two major UV active HS fractions were obtained, which significantly differ in their complexation properties for Cu(II) and Pb(II), respectively.

The present paper describes the certification of the amount content of Cd, Cr and Pb in two different polyethylene materials within the third phase of the Polyethylene Elemental Reference Material (PERM) project. The analytical procedure to establish the reference values for Cd, Cr and Pb amount contents in these materials is based on isotope dilution mass spectrometry used as a primary method of measurement. Cd and Pb were measured with inductively coupled plasma-mass spectrometry and Cr with positive thermal ionization-mass spectrometry. The decomposition of the polymer matrix was carried out using a high pressure asher. Reference values for amount content, traceable to the SI-system, have been obtained for these three elements in both of the polyethylene samples of PERM. For each of the certified amount content values an uncertainty budget was calculated using the method of propagation of uncertainties according to ISO and EURACHEM guidelines. The measurement procedures, as well as the uncertainty calculations, are described for all three elements. In order to keep the whole certification process as transparent as possible, the preparations of various reagents and materials as well as the sample treatment and blending are described in detail. The mass spectrometry measurements and the data treatment are also explained carefully. The various sources of uncertainty present in the procedure are displayed in the uncertainty budgets. The obtained combined uncertainties for the amount content values were less than 2% relative (k=1) for all investigated elements. The amount contents were in the μmol/kg range, corresponding to mg/kg levels.

The boron isotopic compositions of common synthetic boron products, municipal wastewaters from Switzerland, and three Swiss freshwater lakes were investigated. The delta(11)B values (delta(11)B values are normalized to the standard NIST SRM-951) of synthetic Na-borates (-0.4 to 7.6 parts per thousand) and Ca-Na-borates (-13.4 to -4.9 parts per thousand) overlap with those of natural berate minerals and hence suggest that the isotopic signal of anthropogenic boron is not modified during the manufacturing process. As a result it is possible to predict the isotopic composition of synthetic boron products and their potential impact upon contamination of water resources. The delta(11)B values of municipal wastewaters from two locations in northern Switzerland (-7.7 to -4.5 parts per thousand) reflect utilization of Na/Ca- and/or Ca-borates depleted in B-11. Freshwater lakes from Switzerland (Lake Zurich, Greifensee, Lake Lugano) yielded a delta(11)B range of -1.7 to 7.1 parts per thousand and boron concentrations of 17 to 102 mg L-1. The boron isotopic ratios decrease with increasing boron concentrations, indicating mixing between anthropogenic boron with a low delta(11)B signature and meteoric boron with a heavier isotopic signal. We suggest that the isotopic composition of meteoric boron over central Europe has delta(11)B values in the range of ca. 10 to 20 parts per thousand, whereas in coastal areas the marine component is larger with a higher B-11/B-10 ratio (delta(11)B approximate to 30 parts per thousand).

Isotope-labelling exchange experiments were carried out to investigate the kinetic stability of Cr(III) complexes with humic substances (HS). To compare the results with those of an ion, not expected to form kinetically stable HS complexes with respect to its electron configuration, Cu(II) was investigated under the same conditions. HS solutions of different origin were therefore spiked with 53 Cr(III) or 65 Cu(II) after saturation of HS with chromium and copper of natural isotopic composition. In fractions of metal/HS complexes with different molecular weight, obtained by ultrafiltration and HPLC/ICP-MS using size exclusion chromatography (SEC), respectively, the isotope ratios of chromium and copper were determined by ICP and thermal ionisation mass spectrometry. Distinct differences in the isotopic composition of chromium were found in the permeate of the ultrafiltration compared with the corresponding unseparated solution, which indicates kinetically stable Cr(III)/HS complexes. On the other hand, the copper isotopic composition was identical in the permeate and the unseparated solution, which shows that a total exchange of Cu 2+ ions took place between free and HS complexed copper ions. The SEC/ ICP-MS experiments also resulted in a different isotopic distribution of chromium in the chromatographically separated complexes whereas the copper complexes, separated by SEC, showed identical isotopic composition. The kinetic stability of Cr(III)/HS complexes could be explained by the d 3 electron configuration of Cr 3+ ions, a fact which is well known from classical Cr(III) complexes, and influences substantially the mobility of this heavy metal in the environment.

Different sample treatment procedures were combined with inductively coupled plasma mass spectrometry (ICP-MS) and negative thermal ionisation mass spectrometry (NTI-MS) for the determination of ruthenium traces in photographic emulsions. Dissolution of the samples in concentrated ammonia solution was used in connection with ICP-MS by external calibration, which has the advantage of a simple sample preparation technique but introduces high amounts of the silver matrix into the mass spectrometer. On the other hand, isotope dilution mass spectrometry (IDMS) with an enriched 99Ru spike solution was applied for ICP-MS and NTI-MS measurements, respectively, in connection with a significant reduction of the matrix by AgCl precipitation. In these cases loss of ruthenium by the AgCl precipitate has no effect on the analytical result. The results of the different methods agreed usually well analysing ruthenium traces in the range of 0.1–10 μg per gram emulsion. The detection limits obtained were 4 ng/g for ICP-IDMS, 20 ng/g for NTI-IDMS, and 15 ng/g for ICP-MS with external calibration. Differences in the results between the different methods could mainly be attributed to sample inhomogeneities. ICP-IDMS with silver matrix reduction by AgCl precipitation is recommended as a routine method, NTI-IDMS with the corresponding sample treatment as a calibration method.

The residual or doped element concentration [E] in GaAs measured by SSMS is only accurate with respect to the relative sensitivity coefficient RSCE. For a trace element concentration, the RSCE = [E]SSMS/[E]TRUE is set to unity, if no reference material or method is available to approximate the concentration to the true value. For boron a relative sensitivity coefficient of RSCB = 0.94 ± 0.08 was obtained using TI-IDMS as a reference method. RSCN = 1 is used for nitrogen determinations. A boron and nitrogen detection limit of 4.4 × 1013 cm–3 is achieved. SSMS was used as reference method to calibrate the FTIR factor fE = [E] / Iα due to the integrated local vibrational mode absorption Iα of atomic boron and nitrogen in GaAs. A factor of fB = (12.0 × 2.7) × 1016 cm–1 (517 cm–1) and fN = (7.4 ± 0.1) × 1015 cm–1 (472 cm–1) was obtained for a boron and nine nitrogen containing GaAs samples at 77 K and 10 K, respectively.

Thermal ionization isotope dilution mass spectrometry (TI-IDMS) was used as an oligo-element method for the determination of Cr, Cd and Pb in photographic AgCl emulsions. After addition of an appropriate amount of isotopically enriched spikes ( 53 Cr, 116 Cd and 206 Pb) to the solid samples, the latter were completely dissolved in NH 3 solution, permitting isotopic exchange to take place. Thereafter, AgCl was selectively removed by precipitation, whereby ultrasonic treatment was used to enhance the recovery of the elements of interest. Despite the use of concentrated HNO 3 and H 2 O 2 during further sample processing, preliminary experiments indicated the presence of a substantial remainder of the organic matrix (gelatine). Hence, the analytes of interest were isolated by means of electrolytic deposition on Pt electrodes. Subsequently, the deposits were dissolved from the Pt electrodes using a mixture of concentrated HNO 3 and H 2 O 2 and the solutions evaporated to dryness. The solid residues were taken up in diluted HNO 3 and loaded onto Re filaments. In order to improve the ionization yield, prior to the sample, a silicagel suspension containing AlCl 3 was loaded onto the filament and after sample loading, both H 3 BO 3 (for Cr and Pb) and H 3 PO 4 (for Cd and Pb) were added as further ionization aids. Finally, the isotope ratios of interest ( 52 Cr/ 53 Cr, 114 Cd/ 116 Cd and 206 Pb/ 208 Pb) were determined using thermal ionization mass spectrometry, whereby all three analyte elements were vaporized from the same filament. The limits of detection obtained using this procedure range from 0.4 ng (for Cd) to 4 ng (for Pb). Four different AgCl emulsions were analyzed. For Cr, the concentration found was quite similar for all emulsions analyzed, as it varied between ∼ 40 and ∼ 100 ng/g only. For Cd, very low values were found for all samples analyzed (≤ 3 ng/g). Finally, for Pb a much larger variation from ∼ 10 ng/g up to ∼ 5.5 μg/g was observed. For the sample with the highest Pb content, an excellent agreement could be established between the results obtained using quadrupole-based ICP-IDMS and those using TI-IDMS. For the determination of Cr by means of quadrupole-based ICP-IDMS, an instrument equipped with a ShieldTorch system was used to avoid spectral overlap of the 52 Cr + and 40 Ar 12 C + ion signals. Also in this case, the results obtained are in very good agreement with those obtained using TI-IDMS. The comparison between TI-IDMS and ICP-IDMS also made clear that sample inhomogeneity limits the between-sample precision attainable.

Two different sample treatment methods are used in connection with inductively coupled plasma isotope dilution mass spectrometry for accurate and precise determinations of iodine traces in food samples. 129I-enriched iodate is applied as a spike compound for the isotope dilution step. Extraction of iodine by tetramethylammonium hydroxide (TMAH) solution at high temperatures in a closed vessel is one of the sample treatment methods. The other one is a complete decomposition of the sample with a mixture of perchloric acid and nitric acid using microwave assistance. By analyzing different certified reference materials (three milk powders with different iodine levels, BCR CRM 63, 150, and 151; bovine liver BCR CRM 185), the accuracy of ICP-IDMS with both sample treatment methods could be demonstrated. The relative standard deviation was typically in the range of 0.6-2.8% for iodine concentrations between 0.1 microgram g-1 and 5 micrograms g-1. The detection limit was 8 ng g-1 using sample weights of 0.8 g. In a round robin test, using two different types of infant food samples, the results of the two ICP-IDMS methods and of an ICP-MS method without the isotope dilution technique, but applying the TMAH extraction procedure, agree very well with the mean of results of all participating laboratories also using ICP-MS/TMAH. However, the ICP-IDMS method is faster, more precise, widely independent of matrix effects, and, therefore, relatively accurate, which makes this method especially attractive for use as a routine method.

During August and September 1995 samples of different species of macroalgae were collected from the Kongsfjord on Spitsbergen. These macroalgae were cultivated in incubation vessels under polar conditions and the releasing rates of methylated heavy metal compounds for mercury, lead and cadmium were determined. The analysis of monomethyl and dimethyl mercury was carried out by a gas chromatographic system with atomic fluorescence detection after conversion of monomethyl mercury into the volatile methylethyl mercury compound. A differential pulse anodic stripping voltammetric method was used for the determination of trimethyl lead and monomethyl cadmium, respectively. The different species of macroalgae showed distinct differences in the releasing rate of the various methylated heavy metals. Laminaria saccharina, for example, was found to produce monomethyl mercury, dimethyl mercury and trimethyl lead but no monomethyl cadmium. Fucus distichus released only the two methylated mercury compounds, whereas Desmarestia aculeata showed only production of dimethyl mercury. The releasing rates of ten different types of macroalgae were determined to be in the range of up to 13 pg for methylated mercury and of up to 110 pg for trimethyl lead per gram of wet alga and day by allowing incubation times of 1–5 days. Because permethylated heavy metal compounds show high volatility as well as low solubility in ocean water, they are easily emitted into the atmosphere. If therefore follows from the results of this work that macroalgae can significantly contribute to the atmospheric heavy metal content, especially of mercury by the production of dimethyl mercury, in the clean room compartments of the polar regions.

A mass spectrometric method for the determination of chlorine, bromine and iodine species of humic substances (HS) has been developed by coupling a HPLC system with ICP-MS. Using size exclusion chromatography, the method was applied to the characterization of natural water samples (ground water, seepage water from soil, brown water) and a sewage water sample. Quantification of iodine/HS species was carried out by the on-line isotope dilution technique, which was not possible for bromine and chlorine species because of mass spectroscopic interferences by using a quadrupole ICP-MS. Characteristic fingerprints of the halogen/HS species, correlated with the corresponding UV chromatogram, were obtained dependent on the different origin of HS. Biological influences were indicated when following changes of the iodine/HS species composition by aging. The formation of iodine/HS species from inorganic iodide was investigated by labelling experiments with an 129I– spike solution, resulting in the finding that specific HS fractions are preferably iodinated.

Two different mass spectrometric methods, negative thermal ionization isotope dilution mass spectrometry (NTI-IDMS) and inductively coupled plasma mass spectrometry (ICP-MS), off-line and on-line coupled with anion exchange chromatography, have been developed for simultaneous bromide and bromate determinations in water samples. The detection limits of these methods are in the range of 0.03–0.09 μg/L using a 50 mL sample.The results are independent of the content of other anions, which could be demonstrated by the analyses of six mineral waters containing chloride and sulfate of up to 160 mg/L and 1500 mg/L, respectively. Bromide has been analyzed by the NTI-IDMS method in the range of 10–500 μg/L and bromate in the range of 1–50 μg/L with relative standard deviations of 0.3–1.2% and 0.4–6%. Quantification for the ICP-MS method was carried out by the standard addition technique, which resulted in relative standard deviations of 5.5% for bromide at the 500 μg/L level and of 13% for bromate at the level of about 3 μg/L. These results are compared with those described in the literature for ion chromatographic (IC) and other methods and those obtained in this work by IC using UV detection, which allows high concentrations of chloride in the bromate fraction. The detection limits of this IC method are 6 μg/L for bromide and 30 μg/L for bromate. NTI-IDMS and ICP-MS therefore fit the recommendations of the European Union (detection limit<2.5 μg/L; precision and accuracy better than 25% at the 10 μg/L level) for methods analyzing the carcinogenic bromate much better than IC and other methods applied up to now. As a definitive but time consuming method, NTI-IDMS is preferably applicable as a calibration technique, whereas ICP-MS, with relatively short analysis times, due to on-line coupling with chromatography, can be used as a sensitive and powerful routine method for trace bromide and bromate species in water samples.

Precise boron isotope ratio measurements with negative thermal ionization mass spectrometry were used for the identification of ground water contaminations by leakages of landfills. BO-2thermal ions were produced to determine the 11B/10B isotope ratio, which was expressed as δ11B value in ‰ normalized to the standard reference material NIST SRM 951. For example, household waste influences the boron isotope ratio by specific components such as washing powder. In the case of one investigated landfill low δ11B values correlate well with high boron concentrations in contaminated seepage water samples and vice versa for uncontaminated ground water samples. Possible boron contributions of rainwater were taken into account, determining a boron content of 2.3 μg/L and a δ11B value of 13.1‰ for a representative sample. Such low boron concentrations were determined by isotope dilution mass spectrometry (detection limit 0.3 μg/L) whereas higher contents were also analyzed by a spectrophotometric method. However, different sources of contamination could only be identified by the isotope ratio and not by the concentration of boron.

During the cruise ANT X/1 and 2 of the research vessel Polarstern from November 1991 to March 1992, 39 surface water samples of the Atlantic Ocean from 42°N to 72.5°S were collected and analysed for their concentration of volatile iodinated and brominated hydrocarbons. The concentration of chlorophyll-a was used as an indicator for phytoplankton, which is one of the main producers of iodinated and brominated compounds in the ocean. For determination of chlorophyll-a, fluorescence spectroscopy was applied, whereas the measurement of halogenated volatile hydrocarbons was carried out by a purge and trap system with subsequent gas chromatographic separation and detection by an electron capture detector. With this technique the brominated substances CHBr3, CH2Br2, CHBr2Cl and CHBrCl2 have been detected in the range of <0.03 ng/L to 15 ng/L. For these volatile bromomethanes a distinct concentration profile was found. CHBr3 was always found to be the substance with the highest concentration followed by CH2Br2, CHBr2Cl and CHBrCl2. It could also be shown that in addition to CH3I, which for a long time was believed to be the only volatile iodinated substance in the marine environment, other iodinated substances like CH2ClI, CH2I2 and CH3CH2CH2I exist in the range of <0.01 ng/L to 2.2 ng/L in surface water of the Atlantic Ocean.

An isotope dilution mass spectrometric (IDMS) method, using the formation of positive thermal ions, was developed for Cr(III) and Cr(VI) speciation in aerosol particles. Cr(III) and Cr(VI) spike species, enriched in 53Cr, were applied for the isotope dilution step. After leaching of filter collected aerosol samples by an alkaline solution at pH 13, species separation was carried out by extraction with a liquid anion exchanger in methyl isobutyl ketone. Cr(VI) in the organic phase was re-extracted into an ammoniacal solution and chromium was then isolated from both fractions of species by electrodeposition. Detection limits of 30 pg/m3 for Cr(III) and of 8 pg/m3 for Cr(VI) were achieved in atmospheric aerosols for volumes of air samples of about 120 m3. These low detection limits allowed the determination of chromium species in continental aerosol particles in dependence on different seasons. The Cr(III) /Cr(VI) ratio was always found to be about 0.3 whereas dust from soil erosion, which is probably the primary source of chromium in the atmosphere, showed higher ratios. This indicates that chromium is oxidized in the atmosphere. The accuracy of the method was demonstrated in two interlaboratory comparisons of Cr(VI) determinations in welding dust samples. The IDMS method also contributed to the certification of a corresponding standard reference material organized by the Standard Reference Bureau of the European Union. Chromium speciation, including the determination of elemental chromium Cr(0), was carried out in aerosols of different welding processes for stainless steel. These analyses showed distinct differences in the distribution of chromium species in the welding process and can be used as an exact calibration method for routine methods in this important field of monitoring corresponding working places.

An isotope dilution mass spectrometric (IDMS) method has been developed for the simultaneous determination of the complexes of 11 heavy metals (Ag, Cd, Cu, Mo, Ni, Pb, Tl, U, W, Zn and Zr) with humic substances (HS) by coupling HPLC with ICP-MS and applying the on-line isotope dilution technique. The HPLC separation was carried out with size exclusion chromatography. This HPLC/ICP-IDMS method was applied to samples from a brown water, ground water, sewage and seepage water as well as for a sample containing isolated fulvic acids. The total contents of heavy metals and of their complexes were analyzed in these samples with detection limits in the range of 5–110 ng/L. The analysis of heavy metal/HS complexes from the different waters resulted in characteristic fingerprints of the distribution pattern of heavy metals in the separated HS fractions. A comparison between the total heavy metal concentrations and their portions bound to humic substances showed distinct differences for the various metals. Simultaneous 12 C detection was used for the characterization of HS complexes not identified by UV detection and for the determination of relative DOC concentrations of chromatographic peaks.

The distribution of dimethylsulphide (DMS), together with the precursor dimethylsulphonio-propionate (DMSP) and the oxidation product dimethylsulphoxide (DMSO), was measured in melt waters on the McMurdo Ice Shelf in the immediate vicinity of Bratina Island. Conductivity in these sulphate dominated ponds was extremely variable, ranging from 0.106–52.3 mS cm−1. Similarly, chlorophyll a concentrations in the pond waters (1–150 μg 1−1) and mats (1.4–33 μg cm−2) differed considerably. The biomass was dominated by benthic felts of phototrophic cyanobacteria, which might act as a source of biogenic sulphur compounds in the ponds. The mean (and ranges) of concentrations of dissolved sulphur compounds (nmol 1−1) were: CS2 0.16 (<0.04–1.29); DMSPd 0.6 (<0.07–8.4); DMS 3.5 (<0.07–183); DMSO 27.9 (15.5–184.5). Very high concentrations of DMSO were ubiquitous in the ponds in the ice-cored moraine region of the ice shelf, with dissolved concentrations having been 1–2 orders of magnitude greater than those of DMS or DMSPd. It is difficult to ascribe the formation of DMSO solely to the conventionally accepted pathways of DMS oxidation by either bacterial activity or photochemical reactions. A direct biosynthetic production from phytoplankton or bacteria might be involved which means that DMSO in aquatic environments could act as a significant source of DMS rather than as a sink as generally supposed.