TNT (2,4,6-trinitrotoluene) readily and predominantly transforms to 2ADNT (2-amino-4,6-dinitrotoluene) and 4ADNT (4-amino-2,6-dinitrotoluene) in environmental matrixes and tissues. Solid phase microextraction (SPME) was used to extract ADNTs (amino-dinitrotoluenes) from tissue as a potential method to investigate the recalcitrance of metabolically-generated ADNTs versus absorbed ADNTs. Tubifex tubifex was allowed to metabolize TNT into ADNTs in 24-hr static non-renewal exposure test followed by 24-hr depuration in clean reconstituted hard water. Polyacrylate-coated (PA) SPME fibers were then deployed and agitated in tissue homogenates containing metabolically-generated ADNTs for 48 hr to provide a measure of available ADNTs. Extractability of ADNTs from T. tubifex tissue containing metabolically-generated ADNTs was significantly less than extractability of ADNTs from T. tubifex tissue containing absorbed ADNTs: 50-60% and 81-90% of expected extractability based on fiber-water partition ratio. The lower SPME extractability of metabolically-generated ADNTs may stem from the unavailability of metabolically-generated ADNTs sequestered in tissue or bound to tissue macromolecules during metabolism of TNT to ADNT. Tissue extractions using SPMEs may be able to estimate such bound organic residues in tissue and serve as potential indicators of toxicological bioavailability and biomagnification potential of tissue-associated organic compounds.

The Rio Gavilan watershed, located in Mexico 's northern Sierra Madre Occidental , has significance in conservation history. Upon visiting the remote, largely un­developed watershed during two hunting trips in the 1930s, renowned conservationist Aldo Leopold thought it was the best picture of land health he had seen. His main indicators of healthy land were slow water runoff rates regulating erosion and historical predator-prey relationships. The visits confirmed Leopold's concept of land health, inspired many of his essays, and helped shape his land ethic. Leopold proposed the area as a control site to research healthy land throughout North America . The proposal never went forward and the area has since been more intensively logged and grazed. This dissertation research used extensive literature review, archives, oral histories, citizen surveys, and rapid assessment of forest, rangeland, riparian, and socioeconomic health to assess impacts of past cultures and update the area's land health status. Projects that could restore land health, such as linked eco-tourism, forest density reduction, and rotational grazing, were assessed for feasibility. Recent critiques of Leopold's land ethic were also reviewed. Results indicate most pre-1940s impacts were light, current land health status is moderate, and local interest exists in restoring land …