Katarina Abrahamsson

Biogenic volatile iodated hydrocarbons in the ocean

Hitherto unnoticed biogenic volatile iodated hydrocarbons have been determined in open ocean and coastal surface waters. The results indicate that iodated substances are produced by planktonic organisms rather than by macroalgae. It is shown that the diversity of iodated organic compounds released in the seawater is larger than was previously suggested. In the global cycling of iodine it is necessary to consider organic compounds other than methyl iodide.

Direct determination of trace amounts of chlorophenols in fresh water, waste water and sea water

Chlorophenols were acetylated and the derivatives extracted by the simultaneous addition of acetic anhydride and hexane directly to the water sample. The extracts were then analysed by glass capillary column gas chromatography with electron-capture detection. Determination of chlorinated phenols at micrograms/l concentration levels requires only 5 ml of sample. At ng/l levels a 100-ml sample is sufficient. The total time of analysis is 18 min per sample. A comparison between pentafluorobenzoylation and acetylation showed that the acetylated derivatives of chlorophenol isomers separated better on the column. The method has been applied to drinking water, sea water and waste water from a sulphate pulp mill.

Stress-induced production of volatile halogenated organic compounds in Eucheuma denticulatum (Rhodophyta) caused by elevated pH and high light intensities

Eucheuma denticulatum has been shown to release bromoform, diiodomethane, dibromochloromethane, perchloroethylene, chloroiodomethane, chloroform, sec-butyl iodide, methyl iodide, methylchloroform, carbon tetrachloride, trichloroethylene and butyl iodide into its growth media, with bromoform (310 ± 25 μg kg DW−1 h−1) and diiodomethane (182 ± 9 μg kg DW−1 h−1) being the dominant volatile halocarbons (VHCs). The production of VHCs was always higher at a photon flux density of 1500 than at 400 μmol photon m−2 s−1. The influence of pH was minimal at 400 μmol photon m−2 s−1. The addition of azide decreased mean VHC production at pH 8·2 ± 0·2 and 8·8. Algae kept in media where extracellular hydrogen peroxide was decomposed by addition of manganese dioxide showed a decrease in VHC production at pH 8·2 ± 0·2 and an increase at pH 8·8. We suggest that high light intensity and carbon dioxide deficiency caused by high pH in E. denticulatum promote VHC production through induction of hydrogen peroxide synthesis.

A study of the diurnal variation of biogenic volatile halocarbons

The diurnal variation of a number of naturally produced volatile halogenated organic compounds (VHOC) in a pool at Gran Canaria, Spain, is shown. The diurnal cycle was studied both in water and air samples. The highest production rates of VHOC were observed at mid-day, when the photosynthesis of the algae was assumed to be maximal. A second production period was observed after sunset, probably caused by algal respiration. The production rates were found to be equal during light and dark conditions. The measured rates correspond well to our earlier laboratory experiments. A rapid decrease in the concentration of VHOC in the water was observed, and the magnitude of the decrease is compared with the calculated emission of VHOC to the atmosphere. The diurnal cycle of chlorinated and brominated compounds, as well as for 1-iodobuthane, differed from those of iodomethane and 2-iodopropane, probably due to different formation pathways.

Effects of temperature on the production of hydrogen peroxide and volatile halocarbons by brackish-water algae

Marine algae produce volatile halocarbons, which have an ozone-depleting potential. The formation of these compounds is thought to be related to oxidative stress, involving H2O2 and algal peroxidases. In our study we found strong correlations between the releases of H2O2 and brominated and some iodinated compounds to the seawater medium, but no such correlation was found for CHCl3, suggesting the involvement of other formation mechanisms as well. Little is known about the effects of environmental factors on the production of volatile halocarbons by algae and in the present study we focused on the influence of temperature. Algae were sampled in an area of the brackish Baltic Sea that receives thermal discharge, allowing us to collect specimens of the same species that were adapted to different field temperature regimes. We exposed six algal species (the diatom Pleurosira laevis, the brown alga Fucus vesiculosus and four filamentous green algae, Cladophora glomerata, Enteromorpha ahlneriana, E. flexuosa and E. intestinalis) to temperature changes of 0-11 degrees C under high irradiation to invoke oxidative stress. The production rates, as well as the quantitative composition of 16 volatile halocarbons, were strongly species-dependent and different types of responses to temperature were recorded. However, no response patterns to temperature change were found that were consistent for all species or for all halocarbons. We conclude that the production of certain halocarbons may increase with temperature in certain algal species, but that the amount and composition of the volatile halocarbons released by algal communities are probably more affected by temperature-associated species shifts. These results may have implications for climatic change scenarios.

SEASONAL VARIABILITY IN POLYUNSATURATED ALDEHYDE PRODUCTION POTENTIAL AMONG STRAINS OF SKELETONEMA MARINOI (BACILLARIOPHYCEAE)1

The cosmopolitan bloom‐forming diatom Skeletonema marinoi Sarno et Zingone is known to produce toxic polyunsaturated aldehydes (PUAs) in response to cell damage that can affect a diverse suite of organisms, including grazing species and competitor plankton species. The production of PUAs in nine different S. marinoi strains isolated at three different times of the year (spring, summer, and autumn) was assessed in relation to the predominant conditions at the time of isolation from Gullmar Fjord, Skagerrak. During the initial stages of growth, PUA production potential of S. marinoi was generally the highest in summer strains, although there was a substantial variation among strains isolated at the same time. Spring strains, however, showed a strong capacity for increased PUA production potential in later stage cultures with diminishing nutrient levels, reaching amounts similar to those observed in summer strains. In contrast, PUA production potentials of summer and autumn strains did not change significantly from the original values. There is negligible grazing pressure during the spring bloom in Gullmar Fjord, but a potential for high competition for resources, such as nutrients, toward the later stages of the bloom. In contrast, grazing pressure is much greater during summer and autumn, and there may also be nutrient limitation at this time. The PUA production potentials of S. marinoi appear to reflect the ecological conditions at the time of isolation with higher production potentials in strains isolated when conditions were likely to be less beneficial for survival.

Multivariate evaluation of doxorubicin surface-enhanced Raman spectra

Multivariate evaluation of surface-enhanced Raman spectra of doxorubicin in plasma was performed. In a principal component analysis (PCA) all spectral features were modelled into three principal components. The major variation of the data was shown to be the variation of doxorubicin Raman signal together with the doxorubicin fluorescence, whereas the variation due to plasma was of minor importance. It was also shown that the surface-enhanced Raman scattering (SERS) measurements were independent on such factors as measurement occasion and silver colloids. The presented results show that with some improvements, quantification of doxorubicin directly in plasma could be possible.

Degradation of halogenated phenols in anoxic natural marine sediments

Abstract Halogenated phenols were added to three anoxic marine sediment samples which were incubated under different conditions. The concentrations of the halogenated phenols were monitored throughout the experiment in order to study their degradation. The results were the following: 1. The main degradation pathway was progressive dehalogenation. The dehalogenation order was ortho > para > meta. 2. Between 6° and 30°C the dehalogenation rate increased for all substances, while a further increase in temperature resulted in a decrease of dehalogenation rate. 3. Bromophenols were degraded faster than chlorophenols. 4. Sediment which had been exposed to effluent water from a paper and pulp mill showed a higher dehalogenation potential. 5. The results indicate that microorganisms associated to particles are responsible for the dehalogenation.

Determination of biogenic and anthropogenic volatile halocarbons in sea water by liquid—liquid extraction and capillary gas chromatography

Abstract A method is presented for the determination of fifteen biogenic and anthropogenic halogenated hydrocarbons, including brominated and iodated compounds, in sea water at concentrations below the nanograms per litre range. The method includes liquid—liquid extraction of the sea water with pentane, gas chromatographic separation and electron-capture detection. The separation was performed on two coupled fused-silica columns of different polarity and film thickness. In this way trichloroethene, bromodichloromethane and dibromomethane could be separated.

Gas chromatographic determination of halogenated organic compounds in water and sediment in the Skagerrak

Abstract Biogenic and anthropogenic volatile halocarbons and chlorinated phenolic compounds were monitored in the Skagerrak. Measurements were made both in water and in sediment by means of gas chromatography with electron-capture detection. The results show that the load of biogenic halocarbons exceeds that of the anthropogenic halocarbons and that the iodinated compounds show a more marked seasonal trend than the brominated compounds. Additionally, it was established that waters of different origins have exclusive sets of biogenic halocarbons. Pentachlorophenol is widely distributed throughout the Skagerrak. It is transported in its dissociated form. The concentration level of other chlorinated phenolics is less than 1 ng/1. However, it could be demonstrated that there is an accumulation of chlorinated phenolics in sediments in the deeper parts of the Skagerrak.