Doctor of Philosophy (Ph.D.)
Virginia Institute of Marine Science
The primary objectives of this research were therefore to evaluate polybrominated diphenyl ether (PBDE) bioavailability to ecologically distinct soil invertebrates exposed to Penta-BDE-treated consumer polyurethane foam (PUF) products and biosolid products with incurred PBDEs. In laboratory bioassays, earthworms (Eisenia fetida) bioaccumulated SigmaPBDEs (47+99+100+183) up to 11,000 mug/kg lipid after 28 days from a mixture of artificial soil and anaerobically-digested sludge biosolid (ADB). Earthworms also bioaccumulated SigmaPBDEs (47+99+100+153+154+183) up to 13,500 and 838,000 mug/kg lipid after 28 d from a mixture of artificial soil and composted sludge biosolid (CB) and Penta-BDE-spiked artificial soil (SAS), respectively. No previous lab studies on bioaccumulation of PBDEs from sludge or sludge-amended soils have been published. Two publications, done by the same research group on the same sites in Sweden, do exist documenting incidental levels of PBDEs in worms collected from historically sludge-amended agricultural fields. In the current research, biota-soil accumulation factors (BSAFs) were appreciably higher (dependent upon dose) than those reported in these Swedish field studies. PBDE usage in Sweden has been much less intense than in North America. Increasing BSAFs with decreasing biosolids-amended soil burdens may indicate that PBDE constituents within these biosolid products may impact earthworms at relatively low levels in soil. The potential for a terrestrial arthropod, the house cricket ( Acheta domesticus) to take up PBDEs directly from consumer PUF was also evaluated in a laboratory bioassay. These insects frequent indoor spaces and discarded materials and hence may have increased access (and thus exposure) to PBDE-treated polymers. Cricket nymphs were reared in proximity to a commercially manufactured Penta-BDE-treated PUF. They accumulated SigmaPBDEs (47+85+99+100+153+154) up to 14,200 mug/kg lipid after 28 days. Non-depurated crickets ingested SigmaPBDE burdens up to 80,600 mug/kg lipid. Owing to the high PBDE content of the PUF (9% by weight) and the fact that much of it likely remained within the polymer matrix, cricket/PUF bioaccumulation factors (BAFs) were on the order of 10-4 to 10-3 for all PBDE congeners. to evaluate real-world biosolid-associated PBDE bioavailability in the soil-associated terrestrial environment, a food web bioaccumulation study was conducted within a Mid-Atlantic US agricultural soil ecosystem receiving long-term (>20 years) sludge amendments. Patterns of those with most intimate contact and reliance on the soil (e.g. earthworms) most closely reflected the soil/biosolid/commercial Penta-BDE fingerprint. PBDEs were BQL in the herbivorous grasshopper, in contrast to the closely related cricket, an omnivorous scavenger. Surprisingly, PBDEs were largely BQL in predaceous wolf spiders regardless of size or trophic level. Penta-BDE constituent biota-soil accumulation factors (BSAFs) ranged from 0.006 (crickets) to 1.2 (earthworms), while BDE-209 BSAFs ranged from 0.07 (earthworms) to 10.5 (millipedes). Lipid and TOC normalized PBDE burdens were strongly correlated for earthworms and ground beetles, perhaps indicative of attainment of steady state accumulation. In general, PBDE burdens decreased in the invertebrates with trophic level at the sludge-amended field. The pattern of carbon (delta13C) and nitrogen (delta 15N) stable isotopes in the taxa sampled suggests different trophic interactions at the non-sludge and sludge-applied fields. However, as only two sites were surveyed, a more exhaustive data set is needed in order to draw more definitive conclusions. Results of these studies provide unequivocal evidence that PBDEs accumulate in soils where biosolids are applied. They also demonstrate that PUF- and biosolid-associated PBDEs are bioavailable and are accumulated to varying degrees by ecologically diverse soil-associated invertebrates. as such, they may become available for uptake by higher order terrestrial consumers, including reptiles, mammals and birds. (Abstract shortened by UMI.).
© The Author
Gaylor, Michael O., "Bioavailability of biosolids- and consumer product-associated polybrominated diphenyl ether (PBDE) flame retardants to terrestrial invertebrates" (2010). Dissertations, Theses, and Masters Projects. Paper 1539616662.