Trace metal fractionation effects between sea water and aerosols from bubble bursting

Laboratory experiments were performed using radioactive tracers of 65Zn, 75Se, 22Na, 137Cs and 152Eu added to natural sea water to determine differences in elemental composition between sea water and aerosol droplets as a function of particle size. The experiments were conducted using a flow of air as a stream of bubbles rising and bursting at the surface of a vessel containing sea water with added radioactive tracers at pH 8. The resultant aerosol cloud was drawn through a cascade impactor which separated particle size fractions for analysis. In a typical experiment 30 ml of sea water, collected in polyethylene no more than a few hours before along a sandy Gulf of Mexico beach, and a stream of clean air, giving bubbles with a rise distance through the water of 1 to 10 cm, were used, and two or more sequential samplings, usually 12 to 24 hours in duration, were made by cascade impactor. The impaction surfaces were then counted by gamma ray spectrometer. Enrichments relative to Na in general vary systematically with particle size and may exceed a factor of 10 but appear to depend on the particular conditions of each experiment, such as the rise distance of the bubbles and the equilibration time between the added tracers and natural constituents in sea water. Fractionation effects, often quite large, appear to be the rule rather than the exception. Consequently, effects transfer of pollutants from water to air is a distinct possibility and should be documented for each substance of interest under varying conditions. At the very least, our results indicate that in the absence of data it is unwise to assume the composition of the marine aerosol, even as a first approximation, to be the same as sea water

Kinetics of iron (II) oxidation in seawater of various pH

The rate of iron(II) oxidation in the North Sea water of pH 5.5-10 in the range 10-25°C has been studied. The oxygenation rate depends linearly on the iron(II) and dissolved oxygen concentrations. The second-order dependence on (OH-), found by several investigators for synthetic solutions, was confirmed in seawater, but only for pOH>6.9. For pOH3 solutions and for seawater can be attributed predominantly to the incorrect assumption of a second-order pOH dependence in natural seawater. The results can be useful, for example, in predicting the effect of dumping acidic iron waste from the titanium-dioxide industry into the ocean

Effects of titanium dioxide industry waste dumping on sea water chemistry

An investigation was made to determine the influence of the dumping of a 1000 ton day-1, on the average, of acid-iron waste from the titanium dioxide industry into the shallow but turbulent Southern Bight of the North Sea. This waste contains some 20% sulphuric acid and 2% iron. After the passage of the barge that discharges 10 ton of waste min-1 into its wake, the vertical and horizontal distributions of the pH, iron-concentrations and turbidity were measured as a function of time. It appeared that a few seconds after the discharge and for a very brief period, the pH was down to approx. 4 and the Fe-concentration was 13 mg l-1. More than 1 min after the discharge a pH below 6 and an iron-level above 3 mg l-1 could not be detected anywhere. The measured factor for waste dilution by sea water, based on the observed acid and iron concentration in the waste and in the discharge track, were around 5,000 after 5 min, 9,000 after 10 min and 80,000 after 20 min. Before and long after the dumping, the total iron-concentration in this Southern Bight area was around 100 µg l-1, but this high level might be due to natural causes

Classification of estuarine particles using automated electron microprobe analysis and multivariate techniques

The suspended particulate matter from a series of stations in an estuary is automatically analyzed for 11 elements on a particle-by-particle basis by using electron microprobe X-ray microanalysis and an automatic image analysis system. The interpretation of the large acquired data set implies numerical multivariate analysis. The developed procedure consists of using cluster analysis on the particles of individual samples, followed by nearest centroid sorting over all samples from the study area. For the Ems estuary, the procedure provided 13 geochemically different particle types of which the relative abundance through the estuary could be followed and interpreted in terms of estuarine mixing processes. The presented methodology could be applied in other studies concerning the characterization of particle populations

Heavy metal contamination in sediments from the Belgian coast and Scheldt estuary

Sixty-two samples of total sediments and the separated clay/silt fractions were analysed by the energy-dispersive X-ray fluorescence spectrometry to evaluate the pollution level and the trends in samples collected along the Belgian coast over a period of 6 yr and at four stations located in the Scheldt estuary where two of these were sampled periodically for 4 yr. Three correction methods for grain size effects were applied, either to the bulk sediment samples or to the clay/silt size fractions, and the results were compared. Local variations on the concentrations in some of the elements determined were used to establish whether they result from an anthropogenic or natural origin. The level of pollution was assessed as a function of the location, sampling date, and depth

Single particle analysis of aerosols, observed in the marine boundary layer during the Monterey Area Ship Tracks Experiment (MAST), with respect to cloud droplet formation

The chemical composition of individual particles >0.2 µm sampled during the MAST-experiment were analysed by SEM-EDX, in combination with multivariate techniques. The objective of this experiment was to identify the mechanisms responsible for the modification of marine stratocumulus clouds by emissions from ships and in a wider sense to provide information on the global processes involved in atmospheric modification of cloud albedo. Aerosols were examined under different MBL pollution levels (clean, intermediately polluted and moderately polluted) in five different reservoirs: background below-cloud and above-cloud aerosol; background cloud droplet residual particles; below-cloud ship plume aerosol and ship track cloud droplet residual particles. In this study a relation was provided between the aerosol emitted from the ship's stack to an effect in cloud. Additionally, a large fraction of the ambient aerosol was found to be composed of organic material or other compounds, consisting of low Z-elements, associated with chlorine. Their number fraction was largest in clean marine boundary layers, and decreased with increasing pollution levels. The fraction of 'transformed sea salt' (Na, Cl, S), on the other hand, increased with the pollution level in the MBL. Only 20% of the particles fell within the detectable range of the analysis

DOPED ALBUMIN : STANDARDIZATION POSSIBILITIES FOR LAMMA-ANALYSIS OF THIN FREEZE-DRIED CRYOSECTIONS OF BIOLOGICAL TISSUE

Au moyen d'une microsonde à impact laser (LAMMA) des coupes à congélation ultrafines d'albumine contenant différents éléments ont été analysées. Dans le but d'évaluer l'utilisation générale de l'albumine "dopée" comme étalon multi-élémentaire, plusieurs caractéristiques analytiques ont été étudiées. Les résultats démontrent des possibilités prometteuses.Thin cryosections of doped albumin were analysed by laser microprobe mass analysis (LAMMA). Several analytical characteristics of this type of standard material were studied to evaluate its general use for multi-element calibration in LAMMA-analysis of biological samples. Results show promising possibilities