Wiegner, T. N. Institute of Marine and Coastal Sciences, Rutgers University, wiegner@ahab.rutgers.edu
Seitzinger, S. N. Institute of Marine and Coastal Sciences, Rutgers University, sybil@ahab.rutgers.edu

Up to 50% of the total nitrogen load carried by rivers is organic. Organic nitrogen enters rivers from a variety of natural and anthropogenic sources including urban and agricultural runoff, rainwater, and forests. It can be degraded by both photochemical and microbial processes. The study presented here compares photochemical and microbial degradation of dissolved organic matter (DOM) from agricultural and forest runoff. Photochemical experiments examined the degradation of DOM by specific wavelengths of light (PAR, UV-A, UV-B) by measuring changes in the DOM and inorganic nutrient pools. Photochemical degradation of DOM was not detected in any of the light treatments for either the agricultural or forest runoff. In contrast, up to 20% of the DOC and 30% of the DON pool was utilized by the microbial population. High bacterial production measurements further indicate that the DOM was rapidly incorporated into microbial biomass. In addition, previous exposure of the DOM to light did not change its lability. Results from this study suggest that photochemical processes are not as efficient at degrading DOM as the microbial community.
Day: Thursday, Feb. 4
Time: 04:00 - 04:15pm
Location: Sweeney Center
Code: SS33TH0400S