C-sense pCO2 sensor used in Carbonate Study

Parameters: pCO2

Friends of Casco Bay is a marine stewardship organization founded in 1989 to improve and protect the environmental health of Casco Bay, Maine. Home to the Casco BAYKEEPER®, we are a founding member of WATERKEEPER® ALLIANCE, a network of more than 240 environmental groups working to protect waters around the globe. We are recognized for our “work-with” approach to seeking effective solutions to problems that threaten the health of our coastal waters by forging collaborations among diverse groups using an ethic that balances economic vitality with environmental health.

One of the goals for Friends of Casco Bay is to develop a better understanding of the variability and drivers of carbonate chemistry in a coastal system. We are deploying the Turner Designs C-sense pCO2 sensor with a PME Submersible Logger alongside a multi-parameter data sonde providing temperature, salinity, dissolved oxygen, chlorophyll, and pH data. Both instruments collect measurements hourly and are secured to a platform in about four meters of water at high tide. We estimated dissolved inorganic carbon, total alkalinity, and omega aragonite using the pH and pCO2 data. We deployed the station in July of this year and expect to leave the station in place year-round.

A very preliminary look at data collected so far reveals predominately seasonal variability with occasional weather-related influences. A strong negative correlation between dissolved oxygen and pCO2 suggests that a dominant control is the balance between productivity and respiration. In addition, the saturation state (omega) of aragonite showed episodic dips below 1.6, a threshold critical in the development of bivalve shells. Generally, these dips occurred during rain events and higher values prevailed under drier conditions.

Bivariate Fit of pCO2(ppm) By ODOsat %

R2 0.72 P <0.0001

Friends of Casco Bay Research Associate Mike Doan prepares to deploy the Turner Designs C-sense pCO2 sensor

Author: Mike Doan,

Institution: Friends of Casco Bay

Casco Bay, Maine, USA