Integrating High-Resolution Coastal Acidification Monitoring Data Across Seven United States Estuaries

Area of Science:

• Environmental Science
• Oceanography
• Water Quality Monitoring

Background:

• Coastal acidification is a growing concern, impacting estuarine ecosystems.
• The United States Environmental Protection Agency's (EPA) National Estuary Program (NEP) initiated a project to assess coastal acidification.
• Autonomous monitoring offers a high-frequency data collection method for estuarine environments.

Purpose of the Study:

• To expand the use of autonomous monitoring for partial pressure of carbon dioxide (pCO2) and pH in seven U.S. estuaries.
• To characterize daily to seasonal trends in estuarine carbonate chemistry.
• To investigate the drivers of pCO2 variability in diverse estuarine settings.

Main Methods:

• Deployed autonomous sensors for high-frequency (hourly to sub-hourly) monitoring of pCO2, pH, temperature, salinity, and dissolved oxygen (DO).
• Collected multi-year data from seven estuaries on the East Coast, West Coast, and Gulf of Mexico.
• Analyzed data to identify trends, covariation between parameters, and regional differences in carbonate chemistry.

Main Results:

• Autonomous sensors successfully captured key environmental parameters under challenging conditions.
• Temperature and pCO2 showed a positive correlation across all monitored water bodies, with higher pCO2 in warmer months.
• The timing of seasonal pCO2 shifts varied by location, influenced by regional climate and processes like coastal upwelling, which significantly impacted West Coast estuaries.

Conclusions:

• Autonomous monitoring is effective for collecting high-quality carbonate chemistry data in estuarine environments.
• Both thermal and non-thermal factors, including regional climate and biogeochemical processes like coastal upwelling, are critical drivers of estuarine pCO2.
• Understanding these drivers is essential for characterizing and managing coastal acidification across different estuarine systems.