Modeling coupled element cycles in coastal plain wetlands subject to saltwater intrusion - linking sulfur dynamics with carbon and nitrogen cycling
Abstract
Interactions of sea-level rise and drought conditions drive salt water intrusion within historically freshwater coastal wetlands. As salt water intrusion increases, biogeochemical cycling will likely shift dramatically, but the rate and shape of the changes are uncertain. To explore the potential implications of increased sulfate from saltwater intrusion on wetland biogeochemical cycles, we incorporate sulfur cycling into an existing model of coupled oxygen, carbon and nitrogen cycling. The model operates based on fundamental principles of stoichiometry and thermodynamics: microbial assemblages use the suite of metabolic pathways that maximize microbial growth, given the available electron donors/acceptors and the stoichiometric ratio of carbon and nitrogen required for building biomass. Using solute concentrations from a coastal wetland experiencing salt water intrusion, we implement the model with and without sulfur cycling, and also compare model results to preliminary assays of wetland soils. Incorporating sulfur cycling introduces interactions between sulfur and nitrogen cycling (e.g., sulfide oxidation with nitrate) and a new suite of metabolic pathways (e.g., sulfate reduction and sulfide oxidation). After a salt water intrusion event, sulfur pathways play a more dominant role in wetland biogeochemistry and change the distribution and magnitude of existing biogeochemical pathways (e.g., denitrification, methanogenesis), which affects carbon and nitrogen cycling as well as trace gas emissions. This modeling approach will provide a tool for exploring hypotheses regarding complex wetland biogeochemical dynamics under changing climatic conditions.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2011
- Bibcode:
- 2011AGUFM.B13E0606H
- Keywords:
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- 0466 BIOGEOSCIENCES / Modeling;
- 0470 BIOGEOSCIENCES / Nutrients and nutrient cycling;
- 0471 BIOGEOSCIENCES / Oxidation/reduction reactions;
- 0497 BIOGEOSCIENCES / Wetlands