Association between lipophilic organic micropollutants and biolipids of marine biota
Teklemariam, T. (1993). Association between lipophilic organic micropollutants and biolipids of marine biota. MSc Thesis. VUB: Brussel. 90 pp.
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Document type: Dissertation
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| Abstract |
The role of biotic lipids in partitioning lipophillic organic micropollutants were investigated on a sample collected from one station at Belgian continental shelf of the North Sea in september, 1992. Lipids were extracted from samples by two separate procedures (total lipid and neutral lipid extractions) and subsequently quantified both as the routine total gravimetric lipid weight or separated into individual lipid classes using Iatroscan TLC-FID system. Comparisons of lipid yield obtained from gravimetric and Iatroscan TLC-FID determinations indicate that, the gravimetric values are always much higher and most probably overestimated by tbe presence of non lipid coextracts which are minimized through separation of individual lipid classes on the chromarods by the latter method. The organochlorine compounds (PCB homolog and pesticide) residue levels observed in the representative species of different marine organisms occupying different trophic levels (particulate matter, bivalve molluscs, crustaceans and fish species) were related to the gravimetric extractable lipid and sum of individual neutral lipid classes obtained after Iatroscan TLC-FID quantifcation. Relatively very weak correlations observed between gravimetric lipid weights and individual PCB homologs and pesticide residue levels became highly significant (P <0.01 in most cases) when using Iatroscan determined total neutral lipid (TNL) fraction. Further detailed statistical analysis of the PCB homologs vs. lipid class relationship reveal that, among the neutral lipids, cholesterol ester, free fatty acids and triglycerides (with increasing order of importance) are the most responsible neutral lipid fractions that explain most of PCB homologs bioaccumulation in the different biotic compartments. A biolipid concentration factor (BLCF) i.e. the concentration in the neutral lipid fraction (excluding free cholesterol) relative to the concentration in the ambient sea water, calculated for PCB homologs having octanol-water partitioning coefficients (Kow) between 5 to 8 were in the order of 3.5 to 7 log units. The pattern of PCB homolog distribution in the sea water and different biotic compartments observed are in good agreement to some earlier literature reports which are mostly explained by the physicochemical properties (such as partitioning coefficients, water solubilities) of the components. In general the results of this work suggests that lipophillic organochlorine compounds partition most in cholesterol free sum neutral lipid fractions and this parameter as obtained by Iatroscan TLC-FID system could provide a more accurate tool for standardization of data for monitoring or trend assessment studies of lipophillic organic micropollutants. |
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