Microplastics disrupt microalgal carbon fixation: Efficiency and underlying mechanisms

Area of Science:

• Environmental Science
• Marine Biology
• Biochemistry

Background:

• Microalgae are crucial for aquatic carbon fixation and cycling.
• The impact of microplastics (MPs) on microalgal carbon fixation remains unclear.
• Understanding MP effects on microalgae is vital for aquatic ecosystem health.

Purpose of the Study:

• To investigate the effects of polyethylene (PE) and polyvinyl chloride (PVC) MPs on the carbon fixation capacity of Chlorella pyrenoidosa.
• To analyze the biochemical and molecular responses of microalgae to MP exposure.
• To assess the implications for aquatic carbon cycling.

Main Methods:

• Incubation of Chlorella pyrenoidosa with PE and PVC MPs for 14 days.
• Measurement of carbon fixation rates, dissolved organic matter (DOM) characteristics, chlorophyll content, and oxidative stress biomarkers.
• Transcriptome analysis to identify gene expression changes.

Main Results:

• PE and PVC MPs inhibited carbon fixation by up to 39.25% at 50 mg/L.
• MPs decreased DOM in water by damaging algal cells, increasing DOM aromaticity and humification.
• MP exposure reduced chlorophyll content, elevated oxidative stress, and altered gene expression related to photosynthesis and metabolism.

Conclusions:

• Microplastics pose a significant threat to microalgal carbon fixation capacity.
• MP-induced damage to microalgae disrupts DOM quality and alters key metabolic pathways.
• These findings highlight the potential negative impacts of microplastics on aquatic carbon cycles.