Method development for serial-extraction of contaminants in fish followed by species comparison of PCB 153 levels in Tench and Roach from Källby waste water treatment pond
Sammanfattning: Two studies were performed in this paper. The first study was a method development examining the possibilities to do a serial extraction of lipids, PCB 153, NSAIDs (non-steroidal anti-inflammatory drugs) and selective serotonin reuptake inhibitors (SSRIs) from a single sample. Five different treatments were tested with three replicates from each individual fish. All samples were first freeze-dried and then the following treatments were executed: First sample series were only cut and PCB-extracted, second sample series were cut, lipid-extracted and PCB-extracted, third sample series were homogenized, filtered, lipid-extracted and PCB-extracted, forth sample series were homogenized, freeze-dried, lipid-extracted and PCB-extracted and the fifth sample series were homogenized, membrane-extracted, freeze-dried, lipid-extracted and PCB-extracted. The treatments were assessed using an analysis of variance (ANOVA) with Tukey-Kramer post hoc tests. Results showed that there was a significant effect of type of treatment (p=0.008) to the amount of extracted lipids. Filtering treatment had a high standard deviation and low mean lipid yield implying that the method is inappropriate for analytical studies. Freeze-drying was the best treatment after cutting with almost as high lipid yields as the cutting treatment. The full membrane extraction treatment however had a low lipid yield. A possible explanation is that the lipids were hydrolyzed from the acid HP-LPME-treatment and therefore partly dissolved in the water phase. However this demands further research and modeling. The second study was a species comparison of PCB 153 concentrations in roach and tench from Källby sewage treatment pond. The study’s main aim was to assess two species with different feed and foraging behaviour’s tendency to accumulate PCBs. Lipids and PCB were extracted using the cutting treatment (as above) and the results were then analysed for difference using a Mann-Whitney test. The stable isotopes ∂13C and ∂15N were also measured and analysed using two sample, unpaired, t-tests. Result showed that both ∂13C and ∂15N were higher in the tench. The species comparison showed no significant results although after lipid normalization the roach indicated higher concentrations of PCB 153 with a p-value of 0.072. The higher concentration of PCB in roach could not be explained although one study in Poland assessing mercury had found similar results (Misztal-Szkudlinska, 2008). Therefore the results are believed to be an effect of either inter- and intra-species variations or possibly experimental flaws such as failure in assessing PCB yield from tench or insufficient amount of replicates.
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