Hendricks, S. P. Murray State University, susan.hendricks@murraystate.edu
White, D. P. Murray State University, david.white@murraystate.edu
Hart, D. R. Tel Aviv University, none

 
PHYSICOCHEMICAL AND HYDROLOGICAL CONDITIONS AND MICROBIAL ACTIVITY WITHIN THE HYPORHEIC STORAGE ZONES OF TWO STREAMS DRAINING CONTRASTING WATERSHEDS IN WESTERN KY AND TN (USA).
 
The hyporheic storage zones of streams with contrasting sediment input and deposition patterns (agricultural vs. forested) were characterized hydrologically and physicochemically over a 2-year period. Conservative tracer injections described the hydraulic characteristics of each stream during high and low flow conditions by fitting an advection-dispersion-transient storage zone model to the tracer concentration data. Storage zone size relative to the free-flowing zone and hydraulic retention factors were dependent on discharge and bed permeability. NH4 and SRP were always significantly higher in hyporheic than in surface water in the agricultural stream, and nitrification an important process in the sediments. NH4 and NO3 and were significantly higher in the hyporheic zone than in surface water of the forested stream. Anaerobic zones occurred more frequently at more sites within the agricultural hyporheic than in the forested hyporheic zone. Microbial biomass, productivity and extracellular enzyme activity (EEA) were comparatively assessed using sediment chambers buried along longitudinal underflow paths in the gravel bars and streambeds. Microbial EEA and productivity were higher where surface water (and dissolved oxygen) infiltration predominated such as in downwelling hyporheic locations and inwelling gravel bar sites in both streams, but differed in magnitude between the streams.
 
Day: Wednesday, Feb. 3
Time: 04:00 - 04:15pm
Location: Eldorado Hotel
 
Code: CS64WE0400E