| |
Presented at the NABS Annual meeting, Athens, Georgia, 2003
in Hyporheic Processes
Spatial patterns of transient storage and nitrate uptake along a stream reach flowing into a mountain lake
C.D. Arp1, M.A. Baker1, and R.O. Hall, Jr.2. 1Department of Biology and the Ecology Center, Utah State University, Logan, Utah 84322-5305, 2Department of Zoology and Physiology, University of Wyoming, Laramie, Wyoming 82071
Studies of stream nutrient cycling typically quantify transient storage as reach–scale metrics without analysis of where storage occurs or reach position within a watershed, such as position relative to lakes. The objective of this study was to identify and characterize locations of transient storage along a 2000 m stream reach that flows into a small lake in the Sawtooth Mountains, Idaho. Following a 2–week continuous solute addition (Br− and 15NO3−), we measured Br− in streamwater of the main channel, backwaters, and subsurface waters at 4 reach locations for 48 h. We also measured nitrate at these locations including 3 streambank locations for 15NO3−. Zones of transient storage were identified in a side-channel (32% streamwater), sub-channel (47%), and streambank (20%) zones, which where predominantly located in the delta region, 500 m above the lake. Nitrate varied among sub-channel zones, ranging from 17 to 135.1 μg/L in sub-channel water (50 cm depth), and we measured 99% removal of 15NO3− during transport to a hyporheic streambank. Hydrometric and tracer streamflow measurements indicate this reach shifts from losing to gaining towards the lake inflow, and transient storage zones may correspond to this gradient with implications to stream biogeochemical processing.
|
|
