Iman Deanparvar, Carthage College

Class Year:

2024

Mentor:

Laura Lapham, Ph.D. Andrew Heyes, Ph.D.

Abstract:

Carbon dioxide (CO₂) is a potent greenhouse gas, and its overabundance in the atmosphere contributes to climate change and ocean acidification, negatively impacting marine and terrestrial life. Estuaries like the Chesapeake Bay are nutrient-dense, so increased rates of photosynthesis and respiration affect the flux of dissolved inorganic carbon (DIC) in the estuarine system. Recent studies have identified the Bay as a source of CO₂ to the atmosphere and continue to monitor temporal and spatial variability over time. To support these efforts, the Chesapeake Biological Laboratory (CBL) has established a long-term monitoring program at its research pier, to assess the partial pressure of CO₂ (pCO₂) in the Bay at surface and bottom depths over time. The data from this study reveal where CO₂ preferentially resides in the water column and can be correlated to water chemistry data to contribute to a more holistic understanding of carbon cycling in the Bay. Throughout the summer, a time series of pCO₂ measurements was produced, and revealed that bottom-water measurements greatly increased toward the end of the time series, while those from surface-water were frequently at equilibrium with pCO₂ values collected from ambient air samples taken over the same time period. Additionally, isotopic data was collected from the pCO₂ samples, and values were frequently lower than air. These findings suggest respiration as the source of CO₂ from the Bay to the atmosphere. The experimental measurements of pCO₂ and isotopic signatures were only weakly correlated to secondary water chemistry variables such as pH, dissolved oxygen (DO), and total algae concentration. However, these findings are preliminary in the scope of the greater monitoring project, so more data and multivariate analyses should be conducted to lengthen the time series and improve the robustness of data analysis.

Location:

Chesapeake Biological Laboratory