Crocodile bones as archives of pollution exposure: lead contamination in Kakadu National Park, and what's in Sweetheart's Osteoderms?
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Date
2001-08-23
Journal Title
Journal ISSN
Volume Title
Publisher
Australian Nuclear Science and Technology Organisation
Abstract
Experimental findings made it then possible to evaluate the hypothesis that the estuarine crocodile osteodermal laminations would record enhanced blood lead concentrations resulting from the ingestion of lead shot. At about 140 days following lead shot ingestion, two osteoderms were removed from each exposed and control animal. SIMS analysis of Pb-208 and Ca-42 signal intensities was then performed on sections that were prepared and analysed using similar methods previously used on field-collected specimens (Twining et al., 1999). These initial findings are consistent with the hypothesis that incremental laminations of the osteoderm will archive a lead signal that responds to enhanced levels of lead in the animal's blood during its life. SEM analysis identified the laminated structure of the osteoderm, however microprobe analysis did not detect appreciable amounts of even Ca and P, although the organic matrix was obviously present. It is proposed that this anomalous result is due to the preparatory tanning of the skin, in acid solution, that could be expected to leach elements from the organic matrix. An analogy is drawn with the decalcified skeletons in the bodies of the Druid sacrifices due their deposition in acid swamp waters in the UK. The challenge is now to sample osteoderms from large crocodiles in the Finniss River, preferably in close proximity to the Rum Jungle mine site, where any archived pollution signal would be more intense, and then repeat this analytical investigation of the osteodermal history of contaminant loadings. © 2002 Commonwealth of Australia
Description
Proceedings are held in hardcopy in ANSTO Library at ANSTO/E-748
Keywords
Acid mine drainage, Blood chemistry, Calcium 42, Ingestion, Reptiles, Rivers, Lead, Contamination, Northern Territory, Australia, Mining, Estuaries, Ion microprobe analysis, Mass spectroscopy
Citation
Jeffree, R. A., Markich, S. J., Hammerton, K. M., & Russell, R. (2002). Crocodile bones as archives of pollution exposure: lead contamination in Kakadu National Park, and what's in Sweetheart's Osteoderms? Paper presented at The Finniss River Symposium, Darwin, Northern Territory, Australia, August 23 - 24, 2001. In S.J. Markich & R. A Jeffree (Eds.), The Finniss River: a natural laboratory of mining impacts - past, present and future, ANSTO : Sydney, ANSTO E/748, (pp. 49-52).