Links between N deposition and Nitrate export from a high-elevation watershed in the Colorado Front Range

Product Type: 

Journal Article

Year: 

2014

Author(s): 

Mast, M.A., D.W. Clow, J.S. Baron, and G.A. Wetherbee

Suggested Citation: 

Mast, M.A., D.W. Clow, J.S. Baron, and G.A. Wetherbee. 2014. Links between N deposition and Nitrate export from a high-elevation watershed in the Colorado Front Range. Environmental Science & Technology. 48(24): 14258-65.

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 1990s, 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.