Polychlorinated Dibenzo-p-Dioxins (PCDDs) and Dibenzofurans (PCDFs) in the Grenland Fjords (Norway)—Disposition, Levels, and Effects

Abstract

Polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) are regarded as highly toxic. Their lipophilicity and persistence also render them subject to bioaccumulation. The Grenlandfjords (southern Norway) have long been polluted by PCDD/Fs through the magnesium production at Herøya (1951–2002). Therefore, extensive environmental monitoring was performed in the area, and the project “Dioxins in the Grenlandfjords—DIG” was launched to study abiotic mass balances, biotic processes and ecological risk. This article describes some results from DIG on the dispositions of PCDD/Fs in the food web and biological effects. Furthermore, data from the Norwegian monitoring of the Grenlandfjords are described. Differences in cod liver PCDD/F levels were found between stations, with the highest concentrations in the inner fjord (the Frierfjord), closest to the pollution source. Furthermore, considerable decreases in the concentrations followed the large discharge reductions (1975 and 1990). Contrary to earlier food web studies on other organochlorines, it was found that the concentrations of PCDD/Fs decline with higher trophic level. Higher chlorinated congeners also constituted a lower percentage of ∑PCDD/Fs higher in the food chain. The results indicated a limited bioaccumulation of PCDD/Fs, especially of higher chlorinated congeners, likely due to reduced membrane permeability (high molecular size), and possibly slow transport through intestinal aqueous phases. Hepatic cod 7-ethoxyresorufin O-deethylase (EROD) activities differed between the Frierfjord and the Eidangerfjord, showing the different PCDD/F exposure in the two fjords. Furthermore, seasonal variations in cytochrome P-450 (CYP) 1A activity were shown, with different responses between genders. The differences were likely linked to the reproductive cycle of the fish.

The project “Dioxins in the Grenlandfjords—DIG” was funded by the Norwegian Research Council (139032/720; the PROFO program) and Norsk Hydro. The project was coordinated by Kristoffer Næs at the Norwegian Institute for Water Research. Other participating institutions were the Institute of Marine Research (Norway), Norsk Hydro Research Centre, Stockholm University/Institute of Applied Environmental Research, and the Norwegian Geotechnical Institute. The Norwegian State Pollution Monitoring Programme is organized by the Norwegian State Pollution Control Authorities (SFT) and has been funded by SFT and the local industry and municipalities.

Notes

^a Not always for δ¹⁵N (maeasured in separate samples):

¹ n for δ¹⁵N = 1,

² n for δ¹⁵N = 2,

³ n for δ¹⁵N = 1,

⁴ n for δ¹⁵N = 15,

⁵ n for δ¹⁵N = 15,

⁶ n for δ¹⁵N = 15,

⁷ n for δ¹⁵N = 15,

⁸ n for δ¹⁵N = 10,

⁹ n for δ¹⁵N = 1,

¹⁰ n for δ¹⁵N = 2,

¹¹ n for δ¹⁵N = 15,

¹² n for δ¹⁵N = 15,

¹³ n for δ¹⁵N = 15,

¹⁴ n for δ¹⁵N = 15,

¹⁵ n for δ¹⁵N = 10.

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