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Digested organics mark vanderhoff12/14/2023 There is little information on how POPs in eggs of different terrestrial, wetland, and aquatic birds share a large urban and rural landscape relate. Therefore, we recommend that biomagnification studies of food webs including endothermic and poikilothermic organisms incorporate differences in body temperature and tissue composition to accurately characterize the biomagnification potential of chemicals. However, trophic magnification factors derived on a fugacity basis (TMFFs), which recognize differences in body temperature and lipid composition between organisms, were greater than corresponding TMFLs primarily because a temperature-induced thermodynamic biomagnification of hydrophobic chemicals occurs when endothermic organisms consume poikilothermic organisms. TMFLs of cVMS in this terrestrial system were similar to those reported in aquatic systems. TMFLs of PCB-153 and p,p'-DDE were 5.6 (2.2 SE) and 6.1 (2.8 SE) and statistically greater than 1 (p < 0.001). Terrestrial trophic magnification factors derived from lipid normalized concentrations (TMFLs) for D5 and D6 were 0.94 (0.17 SE) and 1.1 (0.23 SE) and not statistically different from 1 (p > 0.05) however, the TMFL of D4 was 0.62 (0.11 SE) and statistically less than 1 (p < 0.001). Trophic magnification of cyclic volatile methyl siloxanes (cVMS) in a terrestrial food web was investigated by measuring concentrations of octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6) and two reference chemicals within air and biota samples from an avian food web located in a mixed urban-agricultural landscape. POPs with a log KOA >6 or a log KOW >5 exhibited biomagnification potential in this terrestrial food web. TMFs of the legacy POPs investigated in this terrestrial food web increased in a statistically significant relationship with both the logarithm of the octanol-air (log KOA) and octanal-water partition (log KOW) coefficients of the POPs. TMFs in this terrestrial food web ranged between 1.2 (0.21 SE) and 15 (4.0 SE), indicating that the majority of these POPs are biomagnifying. We determined trophic magnification factors (TMFs) for contaminants that had a 50% or greater detection frequency in all biota samples and compared these terrestrial TMFs to those observed in aquatic systems. Over 100 samples were collected from various trophic levels of the food web including hawk eggs, songbirds, invertebrates, and berries and analysed for concentrations of 38 PCB congeners, 20 OCPs, 20 PBDE congeners, and 7 other brominated flame retardants listed on the Government of Canada's Chemicals Management Plan. Thus, to better understand the bioaccumulative behaviour of chemicals in terrestrial systems, we examined trophic magnification of hydrophobic POPs in an urban terrestrial food web that included an avian apex predator, the Cooper's hawk (Accipiter cooperii). However, studies have shown that some chemicals that are not bioaccumulative in aquatic food webs can biomagnify in terrestrial food webs. Consequently, regulatory agencies in Canada, the United States, and the European Union rely primarily on aquatic information for the bioaccumulation assessment of chemicals. Protocols to assess the bioaccumulation potential of these chemicals within terrestrial systems are far less developed than for aquatic systems. Legacy persistent organic pollutants (POPs), including organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs), persist for generations in the environment and often negatively impact endocrine functions in exposed wildlife.
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