Gold nanoparticle biodissolution by a freshwater macrophyte and its associated microbiome

Area of Science:

• Environmental Science
• Nanotechnology
• Ecotoxicology

Background:

• Predicting nanoparticle fate in aquatic ecosystems requires complex environmental simulations.
• Gold nanoparticles (Au NPs) are increasingly studied for their environmental behavior.

Purpose of the Study:

• To investigate the transformation and accumulation of gold nanoparticles in freshwater wetland mesocosms.
• To understand the role of macrophytes and associated biofilms in nanoparticle biotransformation.

Main Methods:

• Weekly addition of 12 nm Au nanoparticles to large-scale freshwater wetland mesocosms over six months.
• Analysis of gold association with the macrophyte Egeria densa and its biofilms.
• Investigation of Au nanoparticle oxidation and complexation with ligands.

Main Results:

• Approximately 70% of gold accumulated with the macrophyte Egeria densa.
• Pristine Au nanoparticles were fully oxidized and complexed.
• Biofilms accelerated Au nanoparticle dissolution, with highest rates linked to cyanide release and lower metal-resistant taxa.

Conclusions:

• Macrophytes and their associated microbiomes act as significant sinks for nanoparticle accumulation and transformation.
• Nanoparticle biotransformation within these compartments is crucial, even for typically stable nanoparticles.
• The environmental fate of gold nanoparticles is significantly influenced by biological interactions in aquatic systems.