Hyporheic Reaction Potential: A Framework for Predicting Reach Scale Solute Fate and Transport

Area of Science:

• Environmental Science
• Geochemistry
• Hydrology

Background:

• The hyporheic zone, a critical interface between surface water and groundwater, significantly influences contaminant fate and transport.
• Understanding redox reactions within the hyporheic zone is essential for predicting metal behavior in streams.

Purpose of the Study:

• To develop and validate a novel framework, hyporheic reaction potential (HRP), for quantifying the impact of redox reactions on metal fate and transport.
• To apply the HRP framework to iron reactions in metal-impacted alpine streams and differentiate between biogeochemical and physical controls.

Main Methods:

• Development of the hyporheic reaction potential (HRP) metric, incorporating physical and chemical properties of the hyporheic zone.
• Application of HRP using geochemical and geophysical data from tracer studies in two alpine streams under varying flow conditions.
• Analysis of HRP's relationship with discharge and hyporheic zone extent to assess its ability to capture physical influences on chemical reactions.

Main Results:

• The HRP framework successfully delineated contrasting controls on iron fate and transport in two alpine streams: biogeochemical in Mineral Creek and physical in Cement Creek.
• HRP demonstrated a direct correlation with discharge and hyporheic zone extent, indicating its sensitivity to seasonal hydrologic variations.
• The metric effectively captured the physical aspects governing chemical reactions within the hyporheic zone.

Conclusions:

• The hyporheic reaction potential (HRP) provides a robust metric for assessing redox-driven metal fate and transport in streams.
• HRP is broadly applicable to various solutes and reaction networks controlled by hyporheic zone chemical gradients, aiding in understanding redox cycling.
• This framework offers valuable insights for water quality management, mine remediation, and watershed management by quantifying the hyporheic zone's role in metal dynamics.