Impact of landfill characteristics on the atmospheric exposure to halogenated flame retardants in gulls.

Large amounts of consumer products containing halogenated flame retardants (HFRs) are disposed of annually in landfills, which may lead to significant releases of these semi-volatile contaminants into the environment. During their foraging activities in landfills, gulls can be exposed to elevated levels of HFRs in air. Ring-billed gulls (Larus delawarensis) breeding in the densely populated Montreal area (QC, Canada) are significantly exposed to air levels of polybrominated diphenyl ethers (PBDEs) in or in the vicinity of landfills. However, no information is currently available on the specific characteristics of these landfills that can modulate the atmospheric exposure of ring-billed gulls to HFRs. The objective of this study was to investigate how atmospheric exposure in ring-billed gulls to PBDEs and other HFRs is influenced by selected landfill characteristics (i.e., daily cover materials, waste types and tonnage). Miniature passive air samplers (PASs) combined with GPS dataloggers were deployed for ten days during six years on the back of wild-caught ring-billed gulls breeding in the Montreal area. Atmospheric levels of several PBDEs and other HFRs determined in PASs were found to increase with the presence probability of gulls in the two largest landfills using automotive shredder residues as daily cover material. Weather variables including relative humidity and wind speed had a weak influence on atmospheric levels of HFRs in the bird-borne PASs. Our results suggest that automotive shredder residues represent a significant emission source of HFRs into the air of landfills, thus influencing atmospheric exposure of gulls and other birds foraging in these sites.