Climate, not atmospheric deposition, drives the biogeochemical mass-balance of a mountain watershed

Aquatic Geochemistry
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Abstract

Watershed mass-balance methods are valuable tools for demonstrating impacts to water quality from atmospheric deposition and chemical weathering. Owen Bricker, a pioneer of the mass-balance method, began applying mass-balance modeling to small watersheds in the late 1960s and dedicated his career to expanding the literature and knowledge of complex watershed processes. We evaluated long-term trends in surface-water chemistry in the Loch Vale watershed, a 660-ha. alpine/subalpine catchment located in Rocky Mountain National Park, CO, USA. Many changes in surface-water chemistry correlated with multiple drivers, including summer or monthly temperature, snow water equivalent, and the runoff-to-precipitation ratio. Atmospheric deposition was not a significant causal agent for surface-water chemistry trends. We observed statistically significant increases in both concentrations and fluxes of weathering products including cations, SiO2, SO4 2−, and ANC, and in inorganic N, with inorganic N being primarily of atmospheric origin. These changes are evident in the individual months June, July, and August, and also in the combined June, July, and August summer season. Increasingly warm summer temperatures are melting what was once permanent ice and this may release elements entrained in the ice, stimulate chemical weathering with enhanced moisture availability, and stimulate microbial nitrification. Weathering rates may also be enhanced by sustained water availability in high snowpack years. Rapid change in the flux of weathering products and inorganic N is the direct and indirect result of a changing climate from warming temperatures and thawing cryosphere.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Climate, not atmospheric deposition, drives the biogeochemical mass-balance of a mountain watershed
Series title Aquatic Geochemistry
Volume 20
Issue 2-3
Year Published 2014
Language English
Publisher Springer
Contributing office(s) Fort Collins Science Center
Description 15 p.
First page 167
Last page 181
Country United States
Other Geospatial Loch Vale Watershed, Rock Mountain National Park
Online Only (Y/N) N
Additional Online Files (Y/N) N