HR: 09:00h
AN: NB51C-03 INVITED     [Abstracts]
TI: Catchment Geology Affects Nitrogen Export in Streams Draining the Teton Range, Wyoming
AU: * Arango, C P
EM: carango@nd.edu
AF: University of Notre Dame, Department of Biological Sciences, Notre Dame, IN 46556 United States
AU: Tank, J L
EM: jtank@nd.edu
AF: University of Notre Dame, Department of Biological Sciences, Notre Dame, IN 46556 United States
AU: Hall, R O
EM: bhall@uwyo.edu
AF: University of Wyoming, Department of Zoology and Physiology, Laramie, WY 82071 United States
AB: The presence of bedrock minerals containing phosphorus (P) may influence catchment nutrient retention. For example, catchments with P-poor lithology may export atmospheric nitrogen (N) inputs via stream flow to a greater degree than P-replete catchments. The Teton Range in northwest Wyoming presents ideal conditions to test this hypothesis because Teton catchments have varying amounts of P-rich, calcareous bedrock and P-poor, crystalline bedrock, yet all receive roughly equal atmospheric N inputs. Over several days in summer 2004, we measured discharge and sampled water in nearly every stream draining the Teton Range (n=29). Following sample collection, we determined bedrock geology upstream of our sampling points using GIS. All streams we sampled across the P-poor to P-rich lithology gradient had orthophosphate concentrations below detection. Specific conductivity was tightly linked to measures of catchment lithology, increasing with calcium concentration and proportion of calcareous bedrock (multiple linear regression (MLR), r²=0.96, p<0.001). Dissolved inorganic N flux (mgN/s) decreased with increasing specific conductivity and calcareous bedrock area and increased with crystalline bedrock area (MLR, r²=0.79, p<0.001); particulate organic N flux followed the same trend (MLR, r²=0.85, p<0.001). These data support our hypothesis that catchments with P-poor lithology export more N than catchments with P-rich bedrock.
DE: 1806 Chemistry of fresh water
DE: 9901 NABS Student Award - Basic Research
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly