Seasonal manganese transport in the hyporheic zone of a snowmelt-dominated river (East River, Colorado)

Hydrogeology Journal
By: , and 



Manganese (Mn) plays a critical role in river-water quality because Mn-oxides serve as sorption sites for contaminant metals. The aim of this study is to understand the seasonal cycling of Mn in an alpine streambed that experiences large spring snowmelt events and the potential responses to changes in snowmelt timing and magnitude. To address this goal, annual variations in river-water/groundwater interaction and Mn(aq) transport were measured and modeled in the bed of East River, Colorado, USA. In observations and numerical models, oxygenated river water containing dissolved organic carbon (DOC) mixes with groundwater rich in Mn(aq) in the streambed. The mixing depth increases during spring snowmelt when river discharge increases, leading to a greater DOC supply to the hyporheic zone and net respiration of Mn-oxides, despite an enhanced supply of oxygen. As groundwater upwelling resumes during the subsequent baseflow period, Mn(aq)-rich groundwater mixes with oxygenated river water, resulting in net accumulation of Mn-oxides until the bed freezes in winter. To explore potential responses of Mn transport to different climate-induced hydrological regimes, three hydrograph scenarios were numerically modeled (historic, low-snow, and storm) for the Rocky Mountain region. In a warming climate, Mn(aq) export to the river decreases, and Mn(aq) oxidation is favored in the upper streambed sediments over more of the year. One important implication is that the streambed may have an increased sorption capacity for metals over more of the year, leading to potential changes in river-water quality.

Study Area

Publication type Article
Publication Subtype Journal Article
Title Seasonal manganese transport in the hyporheic zone of a snowmelt-dominated river (East River, Colorado)
Series title Hydrogeology Journal
DOI 10.1007/s10040-020-02146-6
Volume 28
Year Published 2020
Language English
Publisher Springer
Contributing office(s) WMA - Earth System Processes Division
Description 19 p.
First page 1323
Last page 1341
Country United States
State Colorado
Other Geospatial East River
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