Polybrominated diphenyl ethers in the grey-headed gull (Larus cirrocephalus) and African sacred ibis (Threskiornis aethiopicus)

Abstract

PBDEs have been studied in different types of birds from varying ecosystems, however, few of the studies have focused particularly on scavenger birds. It is important to study these birds since many scavenging birds forage on sites close to human population. The present study investigated PBDE concentrations in the grey-headed gull (Larus cirrocephalus) and African sacred ibis (Threskiornis aethiopicus) scavenging on a landfill site in Pretoria, South Africa. The detection frequencies of PBDEs in soil, leachate and feather samples ranged from nd to 100%, with the higher PBDE congeners generally displaying higher detection frequencies. Soil samples indicated 100% detection frequency for all the congeners, while the detection frequencies of PBDEs in leachate samples ranged from “not detected” for BDE-209 to 100% for BDE-28 and -183. In the feathers of grey-headed gulls and sacred ibises, seven of the eight PBDEs investigated were detected at high frequencies, 87.5–100% and 28–100% respectively. The mean PBDE concentrations detected in soil samples ranged from 1.23 ng g⁻¹ for BDE-183 to 5.12 ng g⁻¹ for BDE-209. The 45–150 μm particle size fraction yielded higher concentrations of PBDEs than the coarser 250–500 μm fraction. The concentrations of PBDEs in the leachate samples ranged from 0.49 g L⁻¹ for BDE-153 to 1.68 g L⁻¹ for BDE-100. The dominant congeners were BDE-47, -100 and -183, while the least dominant congener was BDE-153. The grey-headed gull had ∑₇BDE 47, 99, 100, 153, 154, 183 and 209 ranging in total from 44.40 to 143.45 ng g⁻¹ (median = 95.10 ng g⁻¹). The ∑₇PBDEs for the African sacred ibis ranged from 70.31 to 608.41 ng g⁻¹ (median = 179.08 ng g⁻¹). Spearman's correlation test revealed no significant relationship between beak length and pollutant burden in L. cirrocephalus feathers, suggesting that pollutant accumulation is not a function of age for these birds. Pearson correlation analysis was carried out for ∑₇ PBDEs versus leachate (r = 0.65), soil (r = 0.52) and feather (r = 0.77) with a statistical significance of p < 0.05. The observed positive correlation may suggest a possible influence of leachate and soil on PBDE concentrations in the feathers. These findings indicated high PBDE concentrations in comparison with similar studies carried out in other parts of the world. This suggested that the avian species investigated in this study may be impacted as a result of PBDE contamination, which may also have similar negative effects on other wildlife and human populations that are exposed to the Ondestepoort landfill.