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(75-06) Distribution of hydrophobic model substances between ice and brine during ice formation in artificial seawater - implications for ecosystem exposure. Thoerngren, John-Olof*,1, Axelman, Johan1, 1 ITM, Stockholm university, Frescativagen 54, Stockholm, Sweden ABSTRACT- A method was developed to separate high saline pore water (brine) from the ice after ice formation and to quantify the model substances in the brine. In the present thesis the distribution of hydrophobic model substances in artificial sea ice, prepared in laboratory, is studied. The artificial seawater was spiked with the model substances and after freezing the brine was separated by centrifugation. The substances were determined fluorometrically and the enrichment in brine was determined to be approximately a factor 2. Considering also the effect of reduced water solubility due to the increased salinity in the brine channels an enrichment of up to a factor 6 in natural systems. Moreover, indications were found of a significant adsorption of POPs to the ice surface in the brine channels. There are therefore reasons to believe that organisms living in brine channels in the sea ice (sympagic) in Arctic marine waters can be exposed to higher fugacity of persistent organic pollutants (POPs) than would a pelagic system be with a corresponding total concentration of POPs in the seawater. Arctic ecosystems based on the ice-associated food web may consequently be more vulnerable to POP contamination. Key words: brine, sea ice, POPs, enrichment |
