Links between N deposition and nitrate export from a high-elevation watershed in the Colorado Front Range.
Long-term patterns of stream nitrate export and atmospheric N deposition were evaluated over three decades in Loch Vale, a high-elevation watershed in the Colorado Front Range. Stream nitrate concentrations increased in the early 1990 s, peaked in the mid-2000s, and have since declined by over 40%, coincident with trends in nitrogen oxide emissions over the past decade. Similarities in the timing and magnitude of N deposition provide evidence that stream chemistry is responding to changes in atmospheric deposition. The response to deposition was complicated by a drought in the early 2000s that enhanced N export for several years. Other possible explanations, including forest disturbance, snow depth, or permafrost melting, could not explain patterns in N export. Our results show that stream chemistry responds rapidly to changes in N deposition in high-elevation watersheds, similar to the response observed to changes in sulfur deposition.
Colorado Water Science Center and ‡Branch of Quality Systems, U.S. Geological Survey , Denver, Colorado 80225, United States.
M Alisa
MA
Mast
David W
DW
Clow
Jill S
JS
Baron
Gregory A
GA
Wetherbee
D000531:Altitude; D057231:Climate Change; D003120:Colorado; D017753:Ecosystem; D009566:Nitrates / Q000737:chemistry*; D009584:Nitrogen / Q000737:chemistry*; D045483:Rivers / Q000737:chemistry; D014872:Water Movements
D009566:Nitrates; D009584:Nitrogen