Hume, N. Univesity of California, Berkeley,
Fleming, M. Civil & Environmental Engineering,
Horne, A. Civil & Environmental Engineering,

We conducted a seven month microcosm experiment to determine the availability of organic carbon associated with hydrolysis and decay of four plant sources representing emergent and floating aquatics in denitrification wetlands. Prior work with large wetland macrocosms indicates that differing wetland plants, which provide the primary carbon substrates for denitrification, produce differing denitrification rates. This suggested that differences in plant morphology (e.g. emergent vs.floating macrophytes) might provide both differing litter surface areas and organic substrate quality and thereby regulate denitrification. Using milled litter to normalize surface area and equal starting carbon mass resulted in differences in DOC across all treatments that explains 64% of the differences in plant specific denitrification rates (p<0.005). Further, the flux of DOC to the water column from Bulrush and Cattail litter was 53% (p<0.0001) of the flux from floating plants (spp. Hydrocotyle, Lemna), consistent with differences in nitrogen removal across all treatments. Although the primary sites of microbial denitrification are the surfaces associated with the semi-decayed plant litter, the findings here suggest that the majority of denitrification activity depends upon the hydrolyzable fraction of organic matter in plant litter.
Day: Thursday, Feb. 4
Time: 11:45 - 12:00pm
Location: Sweeney Center
Code: SS33TH1145S