GEOC 92 |
| Natural organochlorine is ubiquitous in soil humus, but identities of dominant organochlorine molecules and the processes leading to their formation are poorly understood. Since soil organochlorine has been linked to decaying plant material, we examined Cl speciation in decaying oak leaves using X-ray absorption spectroscopy. Aliphatic/aromatic organochlorine and inorganic chloride appear consistently, though their relative proportions do not vary coherently as a function of decay time. The distribution of Cl in individual decaying leaves was probed further by X-ray spectromicroscopy, revealing a low but consistent background concentration of aliphatic organochlorine in leaf tissue as well as sparsely distributed, highly concentrated polychlorinated aromatic “hotspots.” Field experiments indicate that aliphatic organochlorine is present in healthy leaves and persists through degradation. Microscopic correlations and inoculation experiments suggest that fungi play a role in the production of aromatic organochlorine in soil organic material. These findings offer new insight into Cl transformations in soil systems. |
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Physical Chemistry of Soil and Aquifer Systems: A Symposium in Honor of Garrison Sposito
8:15 AM-11:55 AM, Tuesday, 12 September 2006 Moscone Center -- Room 256, Oral
Division of Geochemistry |