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Abstract Chemical weathering in mountain critical zones controls river chemistry and regulates long‐term climate. Mountain landscapes contain diverse landforms created by geomorphic processes, including landslides, glacial moraines, and rock glaciers. These landforms generate unique flowpaths and water‐rock interactions that modify water chemistry as precipitation is transformed to streamflow. Variations in lithology and vegetation also strongly control water chemistry. Prior work has shown that landslides generate increased dissolved solute concentrations in rapidly uplifting mountains. However, there is still uncertainty regarding the magnitude which different geomorphic processes and land cover variations influence solute chemistry across tectonic and climatic regimes. We measured ion concentrations in surface water from areas that drain a variety of landforms and across land cover gradients in the East River watershed, a tributary of the Colorado River. Our results show that landslides produce higher solute concentrations than background values measured in streams draining soil‐mantled hillslopes and that elevated concentrations persist centuries to millennia after landslide occurrence. Channels with active bedrock incision also generate high solute concentrations, whereas solute concentrations in waters draining moraines and rock glaciers are comparable to background values. Solute fluxes from landslides and areas of bedrock incision are 1.6–1.8 times greater than nearby soil‐mantled hillslopes. Carbonic acid weathering dominates surface water samples from watersheds with greater vegetation coverage. Geomorphically enhanced weathering generates hotspots for net CO₂release or sequestration, depending on lithology, that are 1.5–3.5 times greater than background values, which has implications for understanding links among surface processes, chemical weathering, and carbon cycle dynamics in alpine watersheds. 

Abstract Terrestrial production and export of dissolved organic and inorganic carbon (DOC and DIC) to streams depends on water flow and biogeochemical processes in and beneath soils. Yet, understanding of these processes in a rapidly changing climate is limited. Using the watershed‐scale reactive‐transport model BioRT‐HBV and stream data from a snow‐dominated catchment in the Rockies, we show deeper groundwater flow averaged about 20% of annual discharge, rising to ∼35% in drier years. DOC and DIC production and export peaked during snowmelt and wet years, driven more by hydrology than temperature. DOC was primarily produced in shallow soils (1.94 ± 1.45 gC/m²/year), stored via sorption, and flushed out during snowmelt. Some DOC was recharged to and further consumed in the deeper subsurface via respiration (−0.27 ± 0.02 gC/m²/year), therefore reducing concentrations in deeper groundwater and stream DOC concentrations at low discharge. Consequently, DOC was primarily exported from the shallow zone (1.62 ± 0.96 gC/m²/year, compared to 0.12 ± 0.02 gC/m²/year from the deeper zone). DIC was produced in both zones but at higher rates in shallow soils (1.34 ± 1.00 gC/m²/year) than in the deep subsurface (0.36 ± 0.02 gC/m²/year). Deep respiration elevated DIC concentrations in the deep zone and stream DIC concentrations at low discharge. In other words, deep respiration is responsible for the commonly‐observed increasing DOC concentrations (flushing) and decreasing DIC concentrations (dilution) with increasing discharge.  DIC export from the shallow zone was ~66% of annual export but can drop to ∼53% in drier years. Numerical experiments suggest lower carbon production and export in a warmer, drier future, and a higher proportion from deeper flow and respiration processes. These results underscore the often‐overlooked but growing importance of deeper processes in a warming climate.