Determining the role of chemical weathering reactions and hyporheic exchange on silicate concentrations in dry valley streams, Antarctica

Solute concentrations of weathering products in meltwater streams of the McMurdo Dry Valleys, Antarctica increase along the length of the stream. Chemical weathering of silicate minerals within the hyporheic zone is considered to be the primary source of Si to these streams. Si sources were investigated through a tracer injection study conducted on von Guerard Stream. A highly concentrated solution of Si was injected into the stream in an attempt to suppress equilibrium controlled chemical weathering processes. A transient storage model (OTIS) was used to simulate the conservative transport of observed Si concentrations to determine if downstream concentrations continued to increase due to chemical weathering inputs. This study shows that (1) Si was conservatively transported within the stream during the experiment, and (2) chemical weathering processes were effectively suppressed. These results provide further evidence that chemical weathering of silicate minerals is the primary source of Si in von Guerard Stream.