PM05 Bioaccumulation and Kinetics of POPs
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(PM034) Bioaccumulation of toxaphene by swallows from the Rio Grande Valley (Texas).

Smalling, K1, Mora, M2, Maruya, K1, 1 Skidaway Institute of Oceanography, Savannah, GA, USA2 U.S. Geological Survey and Texas A&M University, College Station, TX, USA

ABSTRACT- Avian species from the middle and lower stretches of the Rio Grande (RG) contain elevated levels of organochlorines, particularly DDE and mirex. However, little has been published on residues of toxaphene in this major southwestern U.S. watershed. We analyzed 23 liver composites from swallows (Petrochelidon spp.) collected from 8 sectors along the Rio Grande during 1999-2000 for >20 toxaphene residue congeners using GC-ECD and GC-ECNI-MS. Estimated total toxaphene concentrations (TOX) ranged from 12 to 260 ng/g wet wt. and were highest in samples from the lower Rio Grande Valley (LRGV), near Llano Grande Lake. Toxaphene congener profiles in most/all samples were dominated by 2,2,5-endo,6-exo,8,8,9,10-octachlorobornane (P-42a or B8-806) and contained several Cl7-Cl9 compounds, many of which remain unidentified. In terms of complexity, these profiles appear to be intermediate between invertebrates/fish (complex) and mammals (simple). These results indicate that, in addition to other legacy OC contaminants, toxaphene residues are most concentrated in the LRGV and accumulate at up to hundreds of parts per billion in these insect-eating birds.

Key words: birds, toxaphene, bioaccumulation, Rio Grande Valley

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