Palladium Nanoparticles: Is There a Risk for Aquatic Ecosystems?

Area of Science:

• Environmental Science
• Nanotechnology
• Ecotoxicology

Background:

• Nano-sized palladium (nano-Pd) from automotive catalytic converters can enter aquatic environments.
• Data on the environmental fate and toxicity of nano-Pd in surface waters is limited.

Purpose of the Study:

• To characterize nano-Pd particle size changes in varying ionic strength media.
• To assess the acute toxicity of nano-Pd to aquatic invertebrates (daphnids and chironomids).

Main Methods:

• Particle size analysis of nano-Pd in media with different ionic strengths.
• Acute toxicity testing (96-hour and 144-hour) on Daphnia magna and Chironomus riparius.

Main Results:

• Nano-Pd agglomeration increased with higher ionic strength.
• Marginal acute effects were observed in daphnids and chironomids after 96 hours.
• A 144-hour exposure resulted in an EC50 of 1.23 mg/L for daphnids, indicating long-term effects.

Conclusions:

• Nano-Pd exhibits time-dependent toxicity in aquatic systems.
• Given low environmental concentrations of palladium, the overall aquatic risk from nano-Pd is likely low.