Interaction between microalgae, marine snow and anionic polyacrylamide APAM at marine conditions

Area of Science:

• Environmental Science
• Marine Biology
• Polymer Chemistry

Background:

• Enhanced oil recovery (EOR) often involves polymer injection to increase water viscosity.
• Anionic polyacrylamide (APAM) is a synthetic polymer used in EOR.
• Produced water from EOR operations can introduce APAM into the marine environment.

Purpose of the Study:

• To investigate the potential fate of APAM in seawater.
• To determine if APAM interacts with microalgae or marine snow aggregates.
• To assess the risk of APAM sedimentation via algal transport.

Main Methods:

• Exposure of three microalgae species (autotroph, mixotroph, heterotroph) to fluorescence-tagged APAM.
• Analysis of APAM attachment to algal cells and aggregates using fluorescence microscopy and fluorometry.
• Formation of algal aggregates using a carousel system in natural seawater.

Main Results:

• Negligible attachment of APAM to the studied microalgae species.
• APAM was primarily found in the water phase after separation from aggregates of Thalassiosira rotula.
• No evidence of APAM accumulation in algae-formed aggregates was observed.

Conclusions:

• APAM does not significantly bind to microalgae cells.
• Marine snow formed by algae is unlikely to facilitate the sedimentation of APAM.
• The transport of APAM to the seabed via algal aggregation is not a significant environmental pathway.