No abstract

Temporal trends of polyfluoroalkyl compounds (PFCs) were examined in tawny owl (Strix aluco) eggs collected in Central Norway over a period of 24 years (1986-2009). Concentrations of 12 PFCs, including C(6)-C(8), C(10) perfluoroalkyl sulfonates (PFSAs), perfluorooctane sulfonamide (PFOSA), and C(8)-C(14) perfluoroalkyl carboxylates (PFCAs), were measured, whereas saturated and unsaturated fluorotelomer carboxylates and shorter chain PFSAs and PFCAs were not detected. Perfluorooctane sulfonate (PFOS) was the predominant compound (geometric mean 10.1 ng/g wet weight (ww)), followed by perfluorotridecanoate (PFTriDA) (0.36 ng/g ww) and perfluoroundecanoate (PFUnDA) (0.19 ng/g ww). Significant decreasing concentrations were found for PFOS with an annual decrease of 1.6% (1986-2009), while, conversely, the C(10)-C(13) PFCA concentrations increase significantly with an annual increase of 4.2-12% (1986-2009). Consequently, the contribution of PFOS to the ∑PFCs decreased, whereas the contribution of the ∑PFCAs increased over the time. Toxicological implications for tawny owls are limited, but the maximal PFOS concentration found in this stu0dy is about 20 times lower than the predicted avian no effect concentration (PNEC) which suggest adverse effects caused by PFOS are unlikely. However, tawny owls are exposed to a mixture of various PFCs, and PFCA concentrations still increase.

Eggs (n = 139) from tawny owls (Strix aluco) were collected annually (1986-2004) in Central Norway and analyzed for organochlorines (OCs) and brominated flame retardants (BFRs). p,p'-DDE (2,2-bis(4-chlorophenyl)-1,1-dichloroethene) and polychlorinated biphenyls (PCBs) were the dominating contaminants (mean/median = 2.7/1.7 and 2.9/1.6 microg/g, lipid weight [l.w.], respectively), comprising 90% of the contaminant burden. Other OCs (hexachlorobenzene [HCB], hexachlorocyclohexanes [HCHs], trans-nonachlor and oxychlordane) comprised less than 4% of the contaminant burden. Concentrations of OCs dropped 74-96% during the study period; p,p'-DDE, HCB, beta-HCH, oxychlordane, and PCBs decreased rapidly in the early (1986-1989) study period (23-34% per year; mean = 27.4%), but leveled off to less than 7% (mean = 3.6%) in the late period (2001-2004). The decrease in p,p'-DDE concentrations leveled off in the early 1990s, possibly due to an early ban on the use of DDT. alpha-HCH showed the strongest decline (always > 20% per year), while trans-nonachlor and gamma-HCH dropped at a constant rate of 9% per year. Toxaphene made up less than 0.6% of the measured contaminants (mean/median = 39/13 ng/ g, l.w.), and the concentrations of these compounds were lower in the late period compared to the early period, but not significant. BFRs, including hexabromocyclododecane (HBCD) and polybrominated diphenyl ethers (sigmaPBDE: mean/median = 182/ 85 ng/g, l.w.) made up about 3% of the measured contaminants. sigmaPBDE declined significantly over the study period (62%). Most PBDE congeners declined: significantly for BDE-47 (80% reduction) and BDE-153 (50% reduction), but the patterns differed; i.e., congeners associated with PentaBDE mixtures showed a rapid annual decline early (22-26%) and a slower decline late in the study period (6-12%), while the PBDEs associated with OctaBDE declined at a constant rate (1-4%). This may result from a larger reduction in the use of PentaBDE compared to other PBDE products in Europe.

The relationships between climate variability, feeding conditions, and the annual accumulation of polychlorinated biphenyls (PCB), 1,1-dichloro-2,2-bis (p-chlorophenyl) ethylene (p,p'-DDE) and polybrominated diphenyl ethers (PBDE) in eggs (n = 168) of tawny owls (Strix aluco) were assessed over a 24-year period (1986-2009) in Central Norway. Winter climate variables included the North Atlantic Oscillation (NAO) and snow conditions, whereas feeding conditions were assessed using vole abundance. The concentrations of all compounds declined between 79% (p,p'-DDE) and 86% (PBDE) over the time period. For PCB and p,p'-DDE, the accumulation was positively associated with snow depth, and negatively associated with NAO (i.e., high accumulation in cold and dry winters) when vole abundance was low, suggesting trade-offs between winter severity and feeding conditions. That is, females mobilize more body fat reserves in cold winters when feeding conditions are poor, which results in increased circulating contaminant concentrations and maternal transfer to the eggs. Owls may also have been forced to feed on prey with higher contaminant loads due to restricted prey availability. For the recently banned PBDEs, the accumulation was high when NAO was low, while snow depth was positively associated with PBDE accumulation only when feeding conditions were good. This suggests somewhat different dynamics of PBDE in the environment or in the owls, compared to PCB and p,p'-DDE. However, climate and feeding conditions explained as much of the annual variation in concentrations of all POPs, as the overall decreasing trend over the 24 years. Hence, such factors should be considered in monitoring programs for POPs. Moreover, to better understand the mechanisms of climate effects on POP accumulation, future studies should measure pollutants in different components of the food chain.