Tidal effects on carbon dioxide emission dynamics in intertidal wetland sediments

Area of Science:

• Environmental Science
• Biogeochemistry
• Ecology

Background:

• Intertidal wetlands play a crucial role in global carbon cycling.
• Understanding carbon dioxide (CO2) emission controls in these ecosystems is vital for climate change research.
• Mechanisms governing CO2 release from wetland sediments require further clarification.

Purpose of the Study:

• To investigate the influence of tidal action on CO2 emissions from Spartina alterniflora-covered salt marsh sediments.
• To quantify the transport of dissolved inorganic carbon (DIC) in response to tidal cycles.
• To identify the primary microbial processes responsible for CO2 production.

Main Methods:

• Utilized the static chamber method with an infrared CO2 detector to measure emission fluxes.
• Applied a two-end member mixing model to assess vertical DIC transport.
• Employed 16S rDNA sequencing to analyze microbial communities and respiration processes.

Main Results:

• CO2 emission fluxes were higher during ebb tides compared to flood tides.
• The salt marsh sediment acted as a weak source of atmospheric CO2 (24.44 ± 16.80 mg C m⁻² h⁻¹).
• DIC transport from surface sediment to seawater was observed, with concentration shifts linked to tidal phases.

Conclusions:

• Tidal action is a major driver of CO2 emissions from intertidal wetland sediments.
• Microbial aerobic respiration is the dominant CO2 production pathway in these sediments.
• The study provides insights into the CO2 and DIC source-sink dynamics at the land-ocean interface.