Stream DOC and DIC Response to Climate and Acidification Disturbances at Sleepers River
Abstract
The carbon cycle at the catchment scale is largely driven by biogeochemical processes and environmental conditions. Reactions that produce and consume carbon species are sensitive to both chemical (e.g., pH) and climatic (e.g., temperature, moisture) conditions. External disturbances, like acidification/recovery and climate change, both influence carbon dynamics, though the nature and magnitude of their influence is difficult to identify due to confounding factors over daily to decadal time scales.
We focus our study on the Sleepers River Research Watershed in Vermont, which has exhibited increasing streamwater dissolved organic carbon (DOC) concentrations but relatively stable dissolved inorganic carbon (DIC) concentrations over the past three decades. The primary driver of increased stream DOC has long been debated as either acid rain recovery or climate change. At Sleepers River, acid deposition peaked in the late 20th century and has since decreased. Simultaneously, climate change has increased temperatures and storm frequency and altered snowmelt events. Here we ask: (1) What environmental conditions and biogeochemical processes drive the temporal trends of DOC and DIC at Sleepers River? (2) What are the relative influences of recovery from acidification and climate change on stream carbon chemistry and biogeochemical reaction rates? To address these questions, we use a watershed reactive transport model, HBV-BioRT, to simulate the biogeochemical reactions and hydrologic transport of carbon species at Sleepers River. By manipulating the meteorological forcing and precipitation chemistry in the model, we can quantify the individual and combined effects of external disturbances and identify the predominant drivers of temporal trends. We hypothesize that both disturbances (recovery from acidification and climate change) will affect solute concentrations, but recovery from acidification will be more influential for DOC, while the relatively stable DIC trends are maintained by lithological influence. For climate change disturbances, we expect DOC and DIC export to be more sensitive to increased storm frequency than increased temperatures, though increased temperatures can contribute to earlier snowmelt and the timing of flushing events, thus impacting DOC and DIC export indirectly.- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2022
- Bibcode:
- 2022AGUFM.H56A..06S