Bioaccumulation potential of organic contaminants in an arctic marine food web

A chemical's octanol-water partition coefficient (Kow) and octanol-air partition coefficient (KOA) are important factors affecting environmental fate and bioaccumulation of persistent organic pollutants (POPs). This thesis involved an investigation of various organic chemicals (ranging in Kow and KOA) in a Canadian Arctic marine food web (53' 59' N, 76' 32' W) aimed to (i) determine levels of PCBs, organochlorine pesticides (OCPs), dialkyl phthalate esters (DPEs) and polybrominated diphenyl ethers (PBDEs) in organisms by high resolution gaschromatography/ high resolution mass-spectrometry (HRGCIHRMS), (ii) evaluate the extent of chemical biomagnification and (iii) identify relationships between biomagnification and influential physical-chemical properties such as Kow and KOA. The results show that recalcitrant C15-C1, PCBs (e.g., PCB 153 and 180) typically exhibited the greatest biomagnification potential and continue to be present at parts per million levels in Arctic biota, some 30 years postregulatory action. Predator-prey biomagnification factors (BMFs) of PCB 180 ranged from approximately 11.5 in male ringed seals, 45.7 in male beluga whales and 106.3 in common eider ducks. Relatively polar chemicals such as P-HCH (log Kow =3.8) tetrachlorobenzenes (log Kow = 4.5) and P-endosulfan (log Kow = 3.4) in some cases exhibited substantial biomagnification in seaducks and marine mammals. BMFs of P-HCH ranged from 5.2 in common eider ducks, 26.2 in male ringed seals and 50.5 in male beluga whales. No significant biomagnification of P-HCH was observed in invertebrates and fish, likely due to efficient respiratory elimination via gills to water. Extensive biornagnification of P-HCH in air-breathing animals (birds and marine mammals) is likely due the chemical's high resistance to metabolic transformation and slow respiratory elimination through air-exhalation because of its high KOA, (i.e.,log KOA = 8.9). While DPEs and PBDEs were detected at appreciable levels, they appeared to be biotransformed by organisms, demonstrated by very low BMFs and FWMFs compared to recalcitrant PCBs. Further evidence of biotransformation was supported by the detection of primary metabolites, monoalkyl phthalate esters (MPEs) and hydroxylated and methoxylated brominated, diphenyl ethers (OHBDEs / MeO-BDEs). Future regulatory initiatives should include chemical KOA and the formation of potentially toxic metabolites as criteria for assessing the bioaccumulation potential of POPs.