Biogenic Volatile Organic Compounds from Pennsylvanian Lakes Sampled during the 2024 Algal Bloom Season

Area of Science:

• Environmental Chemistry
• Atmospheric Science
• Ecology

Background:

• Biogenic volatile organic compounds (BVOCs) from aquatic systems affect atmospheric chemistry.
• Freshwater harmful algal blooms (HABs) are increasing globally but their BVOC emissions are poorly quantified.
• Nitrogen-containing BVOCs are underrepresented in atmospheric measurements.

Purpose of the Study:

• Investigate water-to-air gas exchange rates of BVOCs from freshwater lakes during HABs.
• Quantify emissions of nitrogen-containing compounds, including alkylamines, pyrroline, and pyridine.
• Provide insight into the atmospheric implications of HABs in freshwater environments.

Main Methods:

• Collected 18 freshwater lake samples during peak HAB conditions.
• Utilized atmospheric pressure, hydronium chemical ionization mass spectrometry (CIMS) for real-time flux measurements.
• Measured 900 unique masses, focusing on nitrogen-containing BVOCs.

Main Results:

• Ammonia, pyrroline, and pyridine showed the highest emission fluxes.
• First reported real-time freshwater flux measurements for alkylamines, pyrroline, and pyridine.
• No clear correlation found between BVOC fluxes and chlorophyll a/phycocyanin concentrations.

Conclusions:

• Freshwater HABs emit significant nitrogen-containing BVOCs, impacting atmospheric chemistry.
• Emissions may be influenced by factors beyond cyanobacterial concentrations.
• Findings offer foundational data for understanding freshwater BVOC contributions to air quality.