Rao, U. R. Northwestern University, usha@earth.nwu.edu
Hollander, D. R. Northwestern University, david@earth.nwu.edu
Gray, K. A. Northwestern University,
Sirivedhin, T. Northwestern University,

 
COMPARATIVE ISOTOPIC, ELEMENTAL, AND MOLECULAR ANALYSES OF THE SEASONAL CHANGES IN THE DOM AND POM RESERVOIRS IN AN ANTHROPOGENICALLY INFLUENCED RIPARIAN WETLAND
 
The biogeochemical cycling of carbon and nitrogen, and detailed molecular characterizations of the DOM and POM pools in wetlands have received relatively little attention, due to the significant analytical challenges involved. In the present study of a riparian wetland near Chicago, we use an integrated bulk (elemental, isotopic) and molecular (solvent extraction of compounds, pyrolysis-GC-MS, and Compound Specific Isotopic Analyses) analytical approach to assess the influences of source waters (urban, agricultural), season, and hydrology (flowing, non-flowing) on the biogeochemical cycling of DOM and POM. Our results indicate that seasonal controls exert the largest influence on OM in the wetland, with marked variations in [DOM], [POM], and in the ratio of DOM:POM, which changes from 41:59 in July to 97:3 in November. Other evidence (e.g., C/N ratios) suggests that seasonally, nitrogen is primarily cycled in the DOM but not POM pool. DOM and POM display pronounced differences (and sometimes opposite trends) in d15N, d13C, and pyrolysis fingerprints. These results will be discussed in the context of the differences in reactivity and biogeochemical cycling of these two pools of organic matter.
 
Day: Monday, Feb. 1
Time: 03:45 - 04:00pm
Location: Eldorado Hotel
 
Code: SS34MO0345E