Chlorinated hydrocarbons in glaucous gulls (Larus hyperboreus) in the southern part of Svalbard

In 1989, a number of glaucous gulls (Larus hyperboreus) were found dead near a seabird cliff at south Svalbard. In an effort to clucidate the course of death, 12 individuals were sent to the Central Veterinary Institute for autopsy and analysis of chlorinated pesticides and polychlorinated biphenyls (PCBs) in samples of liver, kidney, brain and muscle. Eggs of common and Bru¨nnichʹs guillemots constitute important food for glaucous gulls during the nestling period, thus 13 eggs (3 eggs from common and 10 eggs from Bru¨nnichʹs guillemots) from the same area were also analyzed for organochlorines. The autopsy of the birds did not reveal any specific cause of death. The following chlorinated pesticides were analyzed: hexachlorobenzene (HCB), hexachlorocyclohexanes (α-, β-, γ-HCH), chlordanes (oxychlordane,trans-nonachlor, heptachlor and heptachlor epoxide), the drin group (aldrin, dieldrin) and the DDT group ( o,p′, p,p′DDT, DDD and DDE). Relatively low hepatic concentrations of dieldrin were found (n.d.−0.17 mg/kg wet weight (w.w.), mean 0.04), ∑HCH (n.d.−0.14 mg/kg w.w., mean 0.02), HCB (0.03-1.01 mg/kg w.w., mean 0.51), oxychlordane (0.01-1.85 mg/kg w.w., mean 1.05), p,p′DDE (0.81-5.41 mg/kg w.w., mean 2.98), o,p′DDD (0-0.52 mg/kg w.w., mean 0.14) and ∑DDT (0.9-6.25 mg/kg w.w., mean 2.92). Levels of the other chlorinated pesticides were below the quantification level. Very high concentrations of PCBs were found. The ∑PCB (sum of wet weight concentrations of the 21 individual congeners, the IUPAC nos. 28, 52, 74, 99, 101, 110, 118, 114, 153, 105, 141, 138, 183, 128, 187, 156, 157, 180, 170, 194 and 209) in hepatic tissue was 0.8–32.3 mg/kg w.w. (mean 16.0), in brain 0.9–29.5 mg/kg w.w. (mean 14.8), in kidney 0.4–21.4 mg/kg w.w. (mean 9.7) and in muscle 0.5–6.0 mg/kg w.w. (mean 3.1). The concentrations of the individual PCB congeners are also given. Relatively low concentrations of all the organochlorines were found in guillemot eggs, mean concentrations of ∑DDT and PCBs were 0.25 and 0.47 mg/kg w.w., respectively. A toxicological evaluation of the PCB results is difficult; however, it cannot be excluded that PCBs might have contributed to the death of the gulls.