Effect of woody debris on fluvial system nitrogen:

Beaver Pond Sediment Core Mesocosm Experiments

Our approach:

• Ten cores were taken from each of three RI beaver ponds. Experiments were run at pond temperature in a climate controlled chamber.
• Cores were placed in glass mesocosms, capped and filled with pond water via peristaltic pump, leaving a 1.5 cm headspace.
• Mesocosm ports were left open overnight to allow air circulation, imitating the natural environment of pond sediments. 15N labeled nitrate at low and high concentrations were added to each mesocosm.
• Sample ports were closed and the water was mixed using a stirrer for 1 min/hr for four hours.
• Gas and water samples were taken from each mesocosm at the beginning and end of the incubation.

Preliminary results:

View Julia Hyman's talk from the 2012 AWRA Riparian Conference:

Woody debris: Denitrification hotspots and nitrous oxide production in fluvial systems (pdf)